Update upstream source from tag 'upstream/6.9.7.1'

Update to upstream version '6.9.7.1'
with Debian dir c2c92e088b7e91033d7f5bee51ac7827148eaf4b

29 files changed, 1658 insertions, 894 deletions

diff --git a/src/Makefile.windows b/src/Makefile.windows
index 11d6fd8..b637772 100644
--- a/src/Makefile.windows
+++ b/src/Makefile.windows
@@ -2,8 +2,9 @@
 
 product_name = oniguruma
 
-TEST_DIR = $(ONIG_DIR)/../test
-WIN_DIR  = $(ONIG_DIR)/../windows
+TEST_DIR   = $(ONIG_DIR)/../test
+SAMPLE_DIR = $(ONIG_DIR)/../sample
+WIN_DIR    = $(ONIG_DIR)/../windows
 
 CPPFLAGS =
 CFLAGS = -O2 -nologo /W3
@@ -15,6 +16,8 @@ ARDLL = cl
 ARDLL_FLAGS = -nologo -LD $(LINKFLAGS) -dll
 LINKFLAGS = -link -incremental:no -pdb:none
 
+SAMPLE_CFLAGS = $(CFLAGS) /I$(ONIG_DIR)
+
 INSTALL = install -c
 CP      = copy
 CC = cl
@@ -89,11 +92,6 @@ makeargs = $(MFLAGS) CPPFLAGS='$(CPPFLAGS)' CFLAGS='$(CFLAGS)' CC='$(CC)'
 # targets
 default: all
 
-setup:
-	$(CP) ..\win32\config.h config.h
-	$(CP) ..\win32\testc.c  testc.c
-
-
 all: $(libname) $(dllname)
 
 $(libname): $(libobjs) $(encobjs)
@@ -155,7 +153,7 @@ $(BUILD_DIR)/unicode_fold1_key.obj: $(ONIG_DIR)/unicode_fold1_key.c $(ONIG_DIR)/
 $(BUILD_DIR)/unicode_fold2_key.obj: $(ONIG_DIR)/unicode_fold2_key.c $(ONIG_DIR)/regenc.h $(BUILD_DIR)/config.h
 $(BUILD_DIR)/unicode_fold3_key.obj: $(ONIG_DIR)/unicode_fold3_key.c $(ONIG_DIR)/regenc.h $(BUILD_DIR)/config.h
 
-all-test: test_syntax test_regset test_utf8 testc testp testu
+all-test: test_syntax test_regset test_utf8 test_options test_back testc testp testu
 
 test_syntax: $(TEST_DIR)/test_syntax.c $(libname)
 	$(CC) -nologo /Fe:$@ /I. /I$(ONIG_DIR) /DONIG_EXTERN=extern /utf-8 $(TEST_DIR)/test_syntax.c $(libname)
@@ -166,6 +164,12 @@ test_regset: $(TEST_DIR)/test_regset.c $(libname)
 test_utf8: $(TEST_DIR)/test_utf8.c $(libname)
 	$(CC) -nologo /Fe:$@ /I. /I$(ONIG_DIR) /DONIG_EXTERN=extern /utf-8 $(TEST_DIR)/test_utf8.c $(libname)
 
+test_options: $(TEST_DIR)/test_options.c $(libname)
+	$(CC) -nologo /Fe:$@ /I. /I$(ONIG_DIR) /DONIG_EXTERN=extern /utf-8 $(TEST_DIR)/test_options.c $(libname)
+
+test_back: $(TEST_DIR)/test_back.c $(libname)
+	$(CC) -nologo /Fe:$@ /I. /I$(ONIG_DIR) /DONIG_EXTERN=extern /utf-8 $(TEST_DIR)/test_back.c $(libname)
+
 testc: $(WIN_DIR)/testc.c $(libname)
 	$(CC) -nologo /Fe:$@ /I. /I$(ONIG_DIR) /DONIG_EXTERN=extern $(WIN_DIR)/testc.c $(libname)
 
@@ -176,14 +180,17 @@ testu: $(TEST_DIR)/testu.c $(libname)
 	$(CC) -nologo /Fe:$@ /I. /I$(ONIG_DIR) /DONIG_EXTERN=extern $(TEST_DIR)/testu.c $(libname)
 
 clean:
-	del $(BUILD_DIR)\*.obj $(BUILD_DIR)\*.lib $(BUILD_DIR)\*.exp $(BUILD_DIR)\*.dll $(BUILD_DIR)\test_regset.exe $(BUILD_DIR)\test_syntax.exe $(BUILD_DIR)\test_utf8.exe $(BUILD_DIR)\testp.exe $(BUILD_DIR)\testc.exe $(BUILD_DIR)\testu.exe
+	del $(BUILD_DIR)\*.obj $(BUILD_DIR)\*.lib $(BUILD_DIR)\*.exp $(BUILD_DIR)\*.dll $(BUILD_DIR)\test_regset.exe $(BUILD_DIR)\test_syntax.exe $(BUILD_DIR)\test_utf8.exe $(BUILD_DIR)\test_options.exe $(BUILD_DIR)\test_back.exe $(BUILD_DIR)\testp.exe $(BUILD_DIR)\testc.exe $(BUILD_DIR)\testu.exe
 
 
 samples: all
-	$(CC) $(CFLAGS) -I. /Fe:simple  $(ONIG_DIR)\sample\simple.c  $(dlllib)
-	$(CC) $(CFLAGS) -I. /Fe:posix   $(ONIG_DIR)\sample\posix.c   $(dlllib)
-	$(CC) $(CFLAGS) -I. /Fe:names   $(ONIG_DIR)\sample\names.c   $(dlllib)
-	$(CC) $(CFLAGS) -I. /Fe:listcap $(ONIG_DIR)\sample\listcap.c $(dlllib)
-	$(CC) $(CFLAGS) -I. /Fe:sql     $(ONIG_DIR)\sample\sql.c     $(dlllib)
-	$(CC) $(CFLAGS) -I. /Fe:encode  $(ONIG_DIR)\sample\encode.c  $(dlllib)
-	$(CC) $(CFLAGS) -I. /Fe:syntax  $(ONIG_DIR)\sample\syntax.c  $(dlllib)
+	$(CC) $(SAMPLE_CFLAGS) /Fe:simple  $(SAMPLE_DIR)\simple.c  $(dlllib)
+	$(CC) $(SAMPLE_CFLAGS) /Fe:posix   $(SAMPLE_DIR)\posix.c   $(dlllib)
+	$(CC) $(SAMPLE_CFLAGS) /Fe:names   $(SAMPLE_DIR)\names.c   $(dlllib)
+	$(CC) $(SAMPLE_CFLAGS) /Fe:listcap $(SAMPLE_DIR)\listcap.c $(dlllib)
+	$(CC) $(SAMPLE_CFLAGS) /Fe:sql     $(SAMPLE_DIR)\sql.c     $(dlllib)
+	$(CC) $(SAMPLE_CFLAGS) /Fe:encode  $(SAMPLE_DIR)\encode.c  $(dlllib)
+	$(CC) $(SAMPLE_CFLAGS) /Fe:syntax  $(SAMPLE_DIR)\syntax.c  $(dlllib)
+	$(CC) $(SAMPLE_CFLAGS) /Fe:count   $(SAMPLE_DIR)\count.c   $(dlllib)
+	$(CC) $(SAMPLE_CFLAGS) /Fe:regset  $(SAMPLE_DIR)\regset.c  $(dlllib)
+	$(CC) $(SAMPLE_CFLAGS) /Fe:callback_each_match $(SAMPLE_DIR)\callback_each_match.c  $(dlllib)
diff --git a/src/cp1251.c b/src/cp1251.c
index fa20780..36b36f6 100644
--- a/src/cp1251.c
+++ b/src/cp1251.c
@@ -2,7 +2,7 @@
   cp1251.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2006-2019  Byte      <byte AT mail DOT kna DOT ru>
+ * Copyright (c) 2006-2020  Byte      <byte AT mail DOT kna DOT ru>
  *                          K.Kosako
  * All rights reserved.
  *
@@ -105,12 +105,16 @@ static const unsigned short EncCP1251_CtypeTable[256] = {
 };
 
 static int
-cp1251_mbc_case_fold(OnigCaseFoldType flag ARG_UNUSED,
+cp1251_mbc_case_fold(OnigCaseFoldType flag,
              const UChar** pp, const UChar* end ARG_UNUSED, UChar* lower)
 {
   const UChar* p = *pp;
 
-  *lower = ENC_CP1251_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_CP1251_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1;
 }
diff --git a/src/gb18030.c b/src/gb18030.c
index 7409d3e..1da19b4 100644
--- a/src/gb18030.c
+++ b/src/gb18030.c
@@ -30,9 +30,11 @@
 
 #include "regenc.h"
 
-#if 1
+/* #define DEBUG_GB18030 */
 
-#define DEBUG_GB18030(arg)
+#ifndef DEBUG_GB18030
+
+#define DEBUG_OUT(arg)
 
 #else
 
@@ -43,7 +45,7 @@
 /* for printf() */
 #include "regint.h"
 
-#define DEBUG_GB18030(arg) printf arg
+#define DEBUG_OUT(arg) printf arg
 
 #endif
 
@@ -177,8 +179,8 @@ gb18030_is_code_ctype(OnigCodePoint code, unsigned int ctype)
 }
 
 enum state {
-  S_START,
-  S_one_C2,
+  S_START = 0,
+  S_one_C2 = 1,
   S_one_C4,
   S_one_CM,
 
@@ -210,15 +212,43 @@ enum state {
   S_odd_CM_even_C4CM,
 };
 
+#ifdef DEBUG_GB18030
+static char* StateNames[] = {
+  "S_START",
+  "S_one_C2",
+  "S_one_C4",
+  "S_one_CM",
+  "S_odd_CM_one_CX",
+  "S_even_CM_one_CX",
+  "S_one_CMC4",
+  "S_odd_CMC4",
+  "S_one_C4_odd_CMC4",
+  "S_even_CMC4",
+  "S_one_C4_even_CMC4",
+  "S_odd_CM_odd_CMC4",
+  "S_even_CM_odd_CMC4",
+  "S_odd_CM_even_CMC4",
+  "S_even_CM_even_CMC4",
+  "S_odd_C4CM",
+  "S_one_CM_odd_C4CM",
+  "S_even_C4CM",
+  "S_one_CM_even_C4CM",
+  "S_even_CM_odd_C4CM",
+  "S_odd_CM_odd_C4CM",
+  "S_even_CM_even_C4CM",
+  "S_odd_CM_even_C4CM"
+};
+#endif
+
 static UChar*
 gb18030_left_adjust_char_head(const UChar* start, const UChar* s)
 {
   const UChar *p;
   enum state state = S_START;
 
-  DEBUG_GB18030(("----------------\n"));
+  DEBUG_OUT(("----------------\n"));
   for (p = s; p >= start; p--) {
-    DEBUG_GB18030(("state %d --(%02x)-->\n", state, *p));
+    DEBUG_OUT(("%5d: state %-19s (0x%02x)->\n", (int )(p - start), StateNames[state], *p));
     switch (state) {
     case S_START:
       switch (GB18030_MAP[*p]) {
@@ -499,7 +529,7 @@ gb18030_left_adjust_char_head(const UChar* start, const UChar* s)
     }
   }
 
-  DEBUG_GB18030(("state %d\n", state));
+  DEBUG_OUT(("state %-19s\n", StateNames[state]));
   switch (state) {
   case S_START:             return (UChar *)(s - 0);
   case S_one_C2:            return (UChar *)(s - 0);
diff --git a/src/iso8859_1.c b/src/iso8859_1.c
index d75509e..2013e75 100644
--- a/src/iso8859_1.c
+++ b/src/iso8859_1.c
@@ -2,7 +2,7 @@
   iso8859_1.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -114,7 +114,7 @@ apply_all_case_fold(OnigCaseFoldType flag,
 }
 
 static int
-get_case_fold_codes_by_str(OnigCaseFoldType flag ARG_UNUSED,
+get_case_fold_codes_by_str(OnigCaseFoldType flag,
                            const OnigUChar* p, const OnigUChar* end,
                            OnigCaseFoldCodeItem items[])
 {
@@ -123,7 +123,8 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag ARG_UNUSED,
 
   if (0x41 <= *p && *p <= 0x5a) {
     if (*p == LARGE_S && end > p + 1
-        && (*(p+1) == LARGE_S || *(p+1) == SMALL_S)) { /* SS */
+        && (*(p+1) == LARGE_S || *(p+1) == SMALL_S)
+        && CASE_FOLD_IS_NOT_ASCII_ONLY(flag)) { /* SS */
     ss_combination:
       items[0].byte_len = 2;
       items[0].code_len = 1;
@@ -152,7 +153,8 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag ARG_UNUSED,
   }
   else if (0x61 <= *p && *p <= 0x7a) {
     if (*p == SMALL_S && end > p + 1
-        && (*(p+1) == SMALL_S || *(p+1) == LARGE_S)) { /* ss */
+        && (*(p+1) == SMALL_S || *(p+1) == LARGE_S)
+        && CASE_FOLD_IS_NOT_ASCII_ONLY(flag)) { /* ss */
       goto ss_combination;
     }
 
@@ -161,56 +163,58 @@ get_case_fold_codes_by_str(OnigCaseFoldType flag ARG_UNUSED,
     items[0].code[0] = (OnigCodePoint )(*p - 0x20);
     return 1;
   }
-  else if (0xc0 <= *p && *p <= 0xcf) {
-    items[0].byte_len = 1;
-    items[0].code_len = 1;
-    items[0].code[0] = (OnigCodePoint )(*p + 0x20);
-    return 1;
-  }
-  else if (0xd0 <= *p && *p <= 0xdf) {
-    if (*p == 0xdf) {
+  else if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag)) {
+    if (0xc0 <= *p && *p <= 0xcf) {
       items[0].byte_len = 1;
-      items[0].code_len = 2;
-      items[0].code[0] = (OnigCodePoint )'s';
-      items[0].code[1] = (OnigCodePoint )'s';
+      items[0].code_len = 1;
+      items[0].code[0] = (OnigCodePoint )(*p + 0x20);
+      return 1;
+    }
+    else if (0xd0 <= *p && *p <= 0xdf) {
+      if (*p == 0xdf) {
+        items[0].byte_len = 1;
+        items[0].code_len = 2;
+        items[0].code[0] = (OnigCodePoint )'s';
+        items[0].code[1] = (OnigCodePoint )'s';
 
-      items[1].byte_len = 1;
-      items[1].code_len = 2;
-      items[1].code[0] = (OnigCodePoint )'S';
-      items[1].code[1] = (OnigCodePoint )'S';
+        items[1].byte_len = 1;
+        items[1].code_len = 2;
+        items[1].code[0] = (OnigCodePoint )'S';
+        items[1].code[1] = (OnigCodePoint )'S';
 
-      items[2].byte_len = 1;
-      items[2].code_len = 2;
-      items[2].code[0] = (OnigCodePoint )'s';
-      items[2].code[1] = (OnigCodePoint )'S';
+        items[2].byte_len = 1;
+        items[2].code_len = 2;
+        items[2].code[0] = (OnigCodePoint )'s';
+        items[2].code[1] = (OnigCodePoint )'S';
 
-      items[3].byte_len = 1;
-      items[3].code_len = 2;
-      items[3].code[0] = (OnigCodePoint )'S';
-      items[3].code[1] = (OnigCodePoint )'s';
+        items[3].byte_len = 1;
+        items[3].code_len = 2;
+        items[3].code[0] = (OnigCodePoint )'S';
+        items[3].code[1] = (OnigCodePoint )'s';
 
-      return 4;
-    }
-    else if (*p != 0xd7) {
-      items[0].byte_len = 1;
-      items[0].code_len = 1;
-      items[0].code[0] = (OnigCodePoint )(*p + 0x20);
-      return 1;
+        return 4;
+      }
+      else if (*p != 0xd7) {
+        items[0].byte_len = 1;
+        items[0].code_len = 1;
+        items[0].code[0] = (OnigCodePoint )(*p + 0x20);
+        return 1;
+      }
     }
-  }
-  else if (0xe0 <= *p && *p <= 0xef) {
-    items[0].byte_len = 1;
-    items[0].code_len = 1;
-    items[0].code[0] = (OnigCodePoint )(*p - 0x20);
-    return 1;
-  }
-  else if (0xf0 <= *p && *p <= 0xfe) {
-    if (*p != 0xf7) {
+    else if (0xe0 <= *p && *p <= 0xef) {
       items[0].byte_len = 1;
       items[0].code_len = 1;
       items[0].code[0] = (OnigCodePoint )(*p - 0x20);
       return 1;
     }
+    else if (0xf0 <= *p && *p <= 0xfe) {
+      if (*p != 0xf7) {
+        items[0].byte_len = 1;
+        items[0].code_len = 1;
+        items[0].code[0] = (OnigCodePoint )(*p - 0x20);
+        return 1;
+      }
+    }
   }
 
   return 0;
@@ -229,7 +233,11 @@ mbc_case_fold(OnigCaseFoldType flag, const UChar** pp,
     return 2;
   }
 
-  *lower = ONIGENC_ISO_8859_1_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ONIGENC_ISO_8859_1_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1;
 }
diff --git a/src/iso8859_10.c b/src/iso8859_10.c
index e98cffb..e4bf599 100644
--- a/src/iso8859_10.c
+++ b/src/iso8859_10.c
@@ -2,7 +2,7 @@
   iso8859_10.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -116,7 +116,11 @@ mbc_case_fold(OnigCaseFoldType flag,
     return 2;
   }
 
-  *lower = ENC_ISO_8859_10_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_ISO_8859_10_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1;
 }
diff --git a/src/iso8859_13.c b/src/iso8859_13.c
index 2bd460f..dbf747f 100644
--- a/src/iso8859_13.c
+++ b/src/iso8859_13.c
@@ -2,7 +2,7 @@
   iso8859_13.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -116,7 +116,11 @@ mbc_case_fold(OnigCaseFoldType flag,
     return 2;
   }
 
-  *lower = ENC_ISO_8859_13_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_ISO_8859_13_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1;
 }
diff --git a/src/iso8859_14.c b/src/iso8859_14.c
index 5030b55..a6d6b71 100644
--- a/src/iso8859_14.c
+++ b/src/iso8859_14.c
@@ -2,7 +2,7 @@
   iso8859_14.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -116,7 +116,11 @@ mbc_case_fold(OnigCaseFoldType flag,
     return 2;
   }
 
-  *lower = ENC_ISO_8859_14_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_ISO_8859_14_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1; /* return byte length of converted char to lower */
 }
diff --git a/src/iso8859_15.c b/src/iso8859_15.c
index f32c3de..0bb6b12 100644
--- a/src/iso8859_15.c
+++ b/src/iso8859_15.c
@@ -2,7 +2,7 @@
   iso8859_15.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -116,7 +116,11 @@ mbc_case_fold(OnigCaseFoldType flag,
     return 2;
   }
 
-  *lower = ENC_ISO_8859_15_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_ISO_8859_15_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1; /* return byte length of converted char to lower */
 }
diff --git a/src/iso8859_16.c b/src/iso8859_16.c
index 22a653a..bfd0a5b 100644
--- a/src/iso8859_16.c
+++ b/src/iso8859_16.c
@@ -2,7 +2,7 @@
   iso8859_16.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -116,7 +116,11 @@ mbc_case_fold(OnigCaseFoldType flag,
     return 2;
   }
 
-  *lower = ENC_ISO_8859_16_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_ISO_8859_16_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1; /* return byte length of converted char to lower */
 }
diff --git a/src/iso8859_2.c b/src/iso8859_2.c
index dc3d0a1..d08140e 100644
--- a/src/iso8859_2.c
+++ b/src/iso8859_2.c
@@ -2,7 +2,7 @@
   iso8859_2.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -116,7 +116,11 @@ mbc_case_fold(OnigCaseFoldType flag,
     return 2;
   }
 
-  *lower = ENC_ISO_8859_2_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_ISO_8859_2_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1; /* return byte length of converted char to lower */
 }
diff --git a/src/iso8859_3.c b/src/iso8859_3.c
index 49dc6b2..69b96fd 100644
--- a/src/iso8859_3.c
+++ b/src/iso8859_3.c
@@ -2,7 +2,7 @@
   iso8859_3.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -116,7 +116,11 @@ mbc_case_fold(OnigCaseFoldType flag, const UChar** pp,
     return 2;
   }
 
-  *lower = ENC_ISO_8859_3_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_ISO_8859_3_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1;
 }
diff --git a/src/iso8859_4.c b/src/iso8859_4.c
index f3f6ba9..949b7a1 100644
--- a/src/iso8859_4.c
+++ b/src/iso8859_4.c
@@ -2,7 +2,7 @@
   iso8859_4.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -116,7 +116,11 @@ mbc_case_fold(OnigCaseFoldType flag,
     return 2;
   }
 
-  *lower = ENC_ISO_8859_4_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_ISO_8859_4_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1; /* return byte length of converted char to lower */
 }
diff --git a/src/iso8859_5.c b/src/iso8859_5.c
index a5f587c..9e5d418 100644
--- a/src/iso8859_5.c
+++ b/src/iso8859_5.c
@@ -2,7 +2,7 @@
   iso8859_5.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -104,12 +104,16 @@ static const unsigned short EncISO_8859_5_CtypeTable[256] = {
 };
 
 static int
-mbc_case_fold(OnigCaseFoldType flag ARG_UNUSED,
+mbc_case_fold(OnigCaseFoldType flag,
               const UChar** pp, const UChar* end ARG_UNUSED, UChar* lower)
 {
   const UChar* p = *pp;
 
-  *lower = ENC_ISO_8859_5_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_ISO_8859_5_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1;
 }
diff --git a/src/iso8859_7.c b/src/iso8859_7.c
index 018efac..07b1360 100644
--- a/src/iso8859_7.c
+++ b/src/iso8859_7.c
@@ -2,7 +2,7 @@
   iso8859_7.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -104,12 +104,16 @@ static const unsigned short EncISO_8859_7_CtypeTable[256] = {
 };
 
 static int
-mbc_case_fold(OnigCaseFoldType flag ARG_UNUSED,
+mbc_case_fold(OnigCaseFoldType flag,
               const UChar** pp, const UChar* end ARG_UNUSED, UChar* lower)
 {
   const UChar* p = *pp;
 
-  *lower = ENC_ISO_8859_7_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_ISO_8859_7_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1;
 }
diff --git a/src/iso8859_9.c b/src/iso8859_9.c
index 1f9bdea..6f205e5 100644
--- a/src/iso8859_9.c
+++ b/src/iso8859_9.c
@@ -2,7 +2,7 @@
   iso8859_9.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -116,7 +116,11 @@ mbc_case_fold(OnigCaseFoldType flag,
     return 2;
   }
 
-  *lower = ENC_ISO_8859_9_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_ISO_8859_9_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1;
 }
diff --git a/src/koi8.c b/src/koi8.c
index 37023c6..90a04f9 100644
--- a/src/koi8.c
+++ b/src/koi8.c
@@ -2,7 +2,7 @@
   koi8.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -105,12 +105,16 @@ static const unsigned short EncKOI8_CtypeTable[256] = {
 
 
 static int
-koi8_mbc_case_fold(OnigCaseFoldType flag ARG_UNUSED,
+koi8_mbc_case_fold(OnigCaseFoldType flag,
                    const UChar** pp, const UChar* end ARG_UNUSED, UChar* lower)
 {
   const UChar* p = *pp;
 
-  *lower = ENC_KOI8_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_KOI8_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1;
 }
diff --git a/src/koi8_r.c b/src/koi8_r.c
index c77302f..31cc870 100644
--- a/src/koi8_r.c
+++ b/src/koi8_r.c
@@ -2,7 +2,7 @@
   koi8_r.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -109,7 +109,11 @@ koi8_r_mbc_case_fold(OnigCaseFoldType flag ARG_UNUSED,
 {
   const UChar* p = *pp;
 
-  *lower = ENC_KOI8_R_TO_LOWER_CASE(*p);
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(*p))
+    *lower = ENC_KOI8_R_TO_LOWER_CASE(*p);
+  else
+    *lower = *p;
+
   (*pp)++;
   return 1;
 }
diff --git a/src/oniguruma.h b/src/oniguruma.h
index d983fc9..a7b9d8f 100644
--- a/src/oniguruma.h
+++ b/src/oniguruma.h
@@ -4,7 +4,7 @@
   oniguruma.h - Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2020  K.Kosako
+ * Copyright (c) 2002-2021  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -36,9 +36,9 @@ extern "C" {
 #define ONIGURUMA
 #define ONIGURUMA_VERSION_MAJOR   6
 #define ONIGURUMA_VERSION_MINOR   9
-#define ONIGURUMA_VERSION_TEENY   6
+#define ONIGURUMA_VERSION_TEENY   7
 
-#define ONIGURUMA_VERSION_INT     60906
+#define ONIGURUMA_VERSION_INT     60907
 
 #ifndef P_
 #if defined(__STDC__) || defined(_WIN32)
@@ -91,6 +91,7 @@ typedef unsigned int OnigCaseFoldType; /* case fold flag */
 
 ONIG_EXTERN OnigCaseFoldType OnigDefaultCaseFoldFlag;
 
+#define ONIGENC_CASE_FOLD_ASCII_ONLY            (1)
 /* #define ONIGENC_CASE_FOLD_HIRAGANA_KATAKANA  (1<<1) */
 /* #define ONIGENC_CASE_FOLD_KATAKANA_WIDTH     (1<<2) */
 #define ONIGENC_CASE_FOLD_TURKISH_AZERI         (1<<20)
@@ -387,9 +388,9 @@ typedef unsigned int        OnigOptionType;
 #define ONIG_OPTION_NOTEOL                    (ONIG_OPTION_NOTBOL << 1)
 #define ONIG_OPTION_POSIX_REGION              (ONIG_OPTION_NOTEOL << 1)
 #define ONIG_OPTION_CHECK_VALIDITY_OF_STRING  (ONIG_OPTION_POSIX_REGION << 1)
-/* #define ONIG_OPTION_CRLF_AS_LINE_SEPARATOR    (ONIG_OPTION_CHECK_VALIDITY_OF_STRING << 1) */
 /* options (compile time) */
-#define ONIG_OPTION_WORD_IS_ASCII        (ONIG_OPTION_CHECK_VALIDITY_OF_STRING << 4)
+#define ONIG_OPTION_IGNORECASE_IS_ASCII  (ONIG_OPTION_CHECK_VALIDITY_OF_STRING << 3)
+#define ONIG_OPTION_WORD_IS_ASCII        (ONIG_OPTION_IGNORECASE_IS_ASCII << 1)
 #define ONIG_OPTION_DIGIT_IS_ASCII       (ONIG_OPTION_WORD_IS_ASCII << 1)
 #define ONIG_OPTION_SPACE_IS_ASCII       (ONIG_OPTION_DIGIT_IS_ASCII << 1)
 #define ONIG_OPTION_POSIX_IS_ASCII       (ONIG_OPTION_SPACE_IS_ASCII << 1)
@@ -399,8 +400,9 @@ typedef unsigned int        OnigOptionType;
 #define ONIG_OPTION_NOT_BEGIN_STRING     (ONIG_OPTION_TEXT_SEGMENT_WORD << 1)
 #define ONIG_OPTION_NOT_END_STRING       (ONIG_OPTION_NOT_BEGIN_STRING << 1)
 #define ONIG_OPTION_NOT_BEGIN_POSITION   (ONIG_OPTION_NOT_END_STRING << 1)
+#define ONIG_OPTION_CALLBACK_EACH_MATCH  (ONIG_OPTION_NOT_BEGIN_POSITION << 1)
 
-#define ONIG_OPTION_MAXBIT               ONIG_OPTION_NOT_BEGIN_POSITION
+#define ONIG_OPTION_MAXBIT               ONIG_OPTION_CALLBACK_EACH_MATCH
 
 #define ONIG_OPTION_ON(options,regopt)      ((options) |= (regopt))
 #define ONIG_OPTION_OFF(options,regopt)     ((options) &= ~(regopt))
@@ -425,6 +427,7 @@ ONIG_EXTERN OnigSyntaxType OnigSyntaxJava;
 ONIG_EXTERN OnigSyntaxType OnigSyntaxPerl;
 ONIG_EXTERN OnigSyntaxType OnigSyntaxPerl_NG;
 ONIG_EXTERN OnigSyntaxType OnigSyntaxRuby;
+ONIG_EXTERN OnigSyntaxType OnigSyntaxPython;
 ONIG_EXTERN OnigSyntaxType OnigSyntaxOniguruma;
 
 /* predefined syntaxes (see regsyntax.c) */
@@ -438,6 +441,7 @@ ONIG_EXTERN OnigSyntaxType OnigSyntaxOniguruma;
 #define ONIG_SYNTAX_PERL               (&OnigSyntaxPerl)
 #define ONIG_SYNTAX_PERL_NG            (&OnigSyntaxPerl_NG)
 #define ONIG_SYNTAX_RUBY               (&OnigSyntaxRuby)
+#define ONIG_SYNTAX_PYTHON             (&OnigSyntaxPython)
 #define ONIG_SYNTAX_ONIGURUMA          (&OnigSyntaxOniguruma)
 
 /* default syntax */
@@ -510,6 +514,7 @@ ONIG_EXTERN OnigSyntaxType*   OnigDefaultSyntax;
 #define ONIG_SYN_OP2_QMARK_BRACE_CALLOUT_CONTENTS (1U<<28) /* (?{...}) (?{{...}}) */
 #define ONIG_SYN_OP2_ASTERISK_CALLOUT_NAME      (1U<<29) /* (*name) (*name{a,..}) */
 #define ONIG_SYN_OP2_OPTION_ONIGURUMA           (1U<<30) /* (?imxWDSPy) */
+#define ONIG_SYN_OP2_QMARK_CAPITAL_P_NAME       (1U<<31) /* (?P<name>...) (?P=name) */
 
 /* syntax (behavior) */
 #define ONIG_SYN_CONTEXT_INDEP_ANCHORS           (1U<<31) /* not implemented */
@@ -525,6 +530,7 @@ ONIG_EXTERN OnigSyntaxType*   OnigDefaultSyntax;
 #define ONIG_SYN_FIXED_INTERVAL_IS_GREEDY_ONLY   (1U<<9)  /* a{n}?=(?:a{n})? */
 #define ONIG_SYN_ISOLATED_OPTION_CONTINUE_BRANCH (1U<<10) /* ..(?i)...|... */
 #define ONIG_SYN_VARIABLE_LEN_LOOK_BEHIND        (1U<<11)  /* (?<=a+|..) */
+#define ONIG_SYN_PYTHON                          (1U<<12)  /* \UHHHHHHHH */
 
 /* syntax (behavior) in char class [...] */
 #define ONIG_SYN_NOT_NEWLINE_IN_NEGATIVE_CC      (1U<<20) /* [^...] */
@@ -548,8 +554,10 @@ ONIG_EXTERN OnigSyntaxType*   OnigDefaultSyntax;
 
 /* error codes */
 #define ONIG_IS_PATTERN_ERROR(ecode)   ((ecode) <= -100 && (ecode) > -1000)
+
 /* normal return */
 #define ONIG_NORMAL                                            0
+#define ONIG_VALUE_IS_NOT_SET                                  1
 #define ONIG_MISMATCH                                         -1
 #define ONIG_NO_SUPPORT_CONFIG                                -2
 #define ONIG_ABORT                                            -3
@@ -607,6 +615,7 @@ ONIG_EXTERN OnigSyntaxType*   OnigDefaultSyntax;
 #define ONIGERR_NUMBERED_BACKREF_OR_CALL_NOT_ALLOWED         -209
 #define ONIGERR_TOO_MANY_CAPTURES                            -210
 #define ONIGERR_TOO_LONG_WIDE_CHAR_VALUE                     -212
+#define ONIGERR_UNDEFINED_OPERATOR                           -213
 #define ONIGERR_EMPTY_GROUP_NAME                             -214
 #define ONIGERR_INVALID_GROUP_NAME                           -215
 #define ONIGERR_INVALID_CHAR_IN_GROUP_NAME                   -216
@@ -633,6 +642,7 @@ ONIG_EXTERN OnigSyntaxType*   OnigDefaultSyntax;
 #define ONIGERR_INVALID_COMBINATION_OF_OPTIONS               -403
 #define ONIGERR_TOO_MANY_USER_DEFINED_OBJECTS                -404
 #define ONIGERR_TOO_LONG_PROPERTY_NAME                       -405
+#define ONIGERR_VERY_INEFFICIENT_PATTERN                     -406
 #define ONIGERR_LIBRARY_IS_NOT_INITIALIZED                   -500
 
 /* errors related to thread */
@@ -717,6 +727,8 @@ typedef struct {
   OnigCaseFoldType   case_fold_flag;
 } OnigCompileInfo;
 
+typedef int (*OnigCallbackEachMatchFunc)(const OnigUChar* str, const OnigUChar* end, const OnigUChar* match_start, OnigRegion* region, void* user_data);
+
 
 /* types for callout */
 typedef enum {
@@ -940,6 +952,12 @@ const char* onig_version P_((void));
 ONIG_EXTERN
 const char* onig_copyright P_((void));
 
+/* for callback each match */
+ONIG_EXTERN
+OnigCallbackEachMatchFunc onig_get_callback_each_match P_((void));
+ONIG_EXTERN
+int onig_set_callback_each_match P_((OnigCallbackEachMatchFunc f));
+
 /* for OnigMatchParam */
 ONIG_EXTERN
 OnigMatchParam* onig_new_match_param P_((void));
@@ -981,6 +999,8 @@ ONIG_EXTERN
 int onig_get_callout_data_by_tag P_((OnigRegex reg, OnigMatchParam* mp, const OnigUChar* tag, const OnigUChar* tag_end, int slot, OnigType* type, OnigValue* val));
 ONIG_EXTERN
 int onig_set_callout_data_by_tag P_((OnigRegex reg, OnigMatchParam* mp, const OnigUChar* tag, const OnigUChar* tag_end, int slot, OnigType type, OnigValue* val));
+ONIG_EXTERN
+int onig_get_callout_data_by_tag_dont_clear_old P_((regex_t* reg, OnigMatchParam* mp, const OnigUChar* tag, const OnigUChar* tag_end, int slot, OnigType* type, OnigValue* val));
 
 /* used in callout functions */
 ONIG_EXTERN
diff --git a/src/regcomp.c b/src/regcomp.c
index dd2b328..d80551d 100644
--- a/src/regcomp.c
+++ b/src/regcomp.c
@@ -2,7 +2,7 @@
   regcomp.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2020  K.Kosako
+ * Copyright (c) 2002-2021  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -31,6 +31,9 @@
 
 #define OPS_INIT_SIZE  8
 
+#define NODE_IS_REAL_IGNORECASE(node) \
+  (NODE_IS_IGNORECASE(node) && !NODE_STRING_IS_CRUDE(node))
+
 typedef struct {
   OnigLen min;
   OnigLen max;
@@ -44,7 +47,7 @@ typedef struct {
 
 OnigCaseFoldType OnigDefaultCaseFoldFlag = ONIGENC_CASE_FOLD_MIN;
 
-static OnigLen node_min_byte_len(Node* node, ScanEnv* env);
+static OnigLen node_min_byte_len(Node* node, ParseEnv* env);
 
 #if 0
 typedef struct {
@@ -129,27 +132,22 @@ ops_init(regex_t* reg, int init_alloc_size)
   Operation* p;
   size_t size;
 
-  if (init_alloc_size > 0) {
-    size = sizeof(Operation) * init_alloc_size;
-    p = (Operation* )xrealloc(reg->ops, size);
-    CHECK_NULL_RETURN_MEMERR(p);
-    reg->ops = p;
+  if (init_alloc_size <= 0)
+    return ONIGERR_PARSER_BUG;
+
+  size = sizeof(Operation) * init_alloc_size;
+  p = (Operation* )xrealloc(reg->ops, size);
+  CHECK_NULL_RETURN_MEMERR(p);
+  reg->ops = p;
 #ifdef USE_DIRECT_THREADED_CODE
-    {
-      enum OpCode* cp;
-      size = sizeof(enum OpCode) * init_alloc_size;
-      cp = (enum OpCode* )xrealloc(reg->ocs, size);
-      CHECK_NULL_RETURN_MEMERR(cp);
-      reg->ocs = cp;
-    }
-#endif
+  {
+    enum OpCode* cp;
+    size = sizeof(enum OpCode) * init_alloc_size;
+    cp = (enum OpCode* )xrealloc(reg->ocs, size);
+    CHECK_NULL_RETURN_MEMERR(cp);
+    reg->ocs = cp;
   }
-  else {
-    reg->ops = (Operation* )0;
-#ifdef USE_DIRECT_THREADED_CODE
-    reg->ocs = (enum OpCode* )0;
 #endif
-  }
 
   reg->ops_curr  = 0; /* !!! not yet done ops_new() */
   reg->ops_alloc = init_alloc_size;
@@ -159,19 +157,16 @@ ops_init(regex_t* reg, int init_alloc_size)
 }
 
 static int
-ops_expand(regex_t* reg, int n)
+ops_resize(regex_t* reg, int n)
 {
-#define MIN_OPS_EXPAND_SIZE   4
-
 #ifdef USE_DIRECT_THREADED_CODE
   enum OpCode* cp;
 #endif
   Operation* p;
   size_t size;
 
-  if (n <= 0) n = MIN_OPS_EXPAND_SIZE;
-
-  n += reg->ops_alloc;
+  if (n == reg->ops_alloc) return ONIG_NORMAL;
+  if (n <= 0) return ONIGERR_PARSER_BUG;
 
   size = sizeof(Operation) * n;
   p = (Operation* )xrealloc(reg->ops, size);
@@ -197,10 +192,8 @@ ops_expand(regex_t* reg, int n)
 static int
 ops_new(regex_t* reg)
 {
-  int r;
-
   if (reg->ops_used >= reg->ops_alloc) {
-    r = ops_expand(reg, reg->ops_alloc);
+    int r = ops_resize(reg, reg->ops_alloc << 1);
     if (r != ONIG_NORMAL) return r;
   }
 
@@ -669,6 +662,8 @@ mmcl_alt_merge(MinMaxCharLen* to, MinMaxCharLen* alt)
   if (to->max < alt->max) to->max = alt->max;
 }
 
+#ifndef ONIG_DONT_OPTIMIZE
+
 static int
 mml_is_equal(MinMaxLen* a, MinMaxLen* b)
 {
@@ -709,9 +704,11 @@ mml_alt_merge(MinMaxLen* to, MinMaxLen* alt)
   if (to->max < alt->max) to->max = alt->max;
 }
 
+#endif
+
 /* fixed size pattern node only */
 static int
-node_char_len1(Node* node, regex_t* reg, MinMaxCharLen* ci, ScanEnv* env,
+node_char_len1(Node* node, regex_t* reg, MinMaxCharLen* ci, ParseEnv* env,
                int level)
 {
   MinMaxCharLen tci;
@@ -768,7 +765,8 @@ node_char_len1(Node* node, regex_t* reg, MinMaxCharLen* ci, ScanEnv* env,
       StrNode* sn = STR_(node);
       UChar *s = sn->s;
 
-      if (NODE_IS_IGNORECASE(node) && ! NODE_STRING_IS_CRUDE(node)) {
+      if (NODE_IS_REAL_IGNORECASE(node) &&
+          CASE_FOLD_IS_NOT_ASCII_ONLY(env->case_fold_flag)) {
         /* Such a case is possible.
            ex. /(?i)(?<=\1)(a)/
            Backref node refer to capture group, but it doesn't tune yet.
@@ -917,7 +915,7 @@ node_char_len1(Node* node, regex_t* reg, MinMaxCharLen* ci, ScanEnv* env,
     {
       int i;
       int* backs;
-      MemEnv* mem_env = SCANENV_MEMENV(env);
+      MemEnv* mem_env = PARSEENV_MEMENV(env);
       BackRefNode* br = BACKREF_(node);
 
       backs = BACKREFS_P(br);
@@ -943,7 +941,7 @@ node_char_len1(Node* node, regex_t* reg, MinMaxCharLen* ci, ScanEnv* env,
 }
 
 static int
-node_char_len(Node* node, regex_t* reg, MinMaxCharLen* ci, ScanEnv* env)
+node_char_len(Node* node, regex_t* reg, MinMaxCharLen* ci, ParseEnv* env)
 {
   return node_char_len1(node, reg, ci, env, 0);
 }
@@ -967,7 +965,7 @@ add_op(regex_t* reg, int opcode)
 }
 
 static int compile_length_tree(Node* node, regex_t* reg);
-static int compile_tree(Node* node, regex_t* reg, ScanEnv* env);
+static int compile_tree(Node* node, regex_t* reg, ParseEnv* env);
 
 
 #define IS_NEED_STR_LEN_OP(op) \
@@ -1035,7 +1033,7 @@ is_strict_real_node(Node* node)
 }
 
 static int
-compile_quant_body_with_empty_check(QuantNode* qn, regex_t* reg, ScanEnv* env)
+compile_quant_body_with_empty_check(QuantNode* qn, regex_t* reg, ParseEnv* env)
 {
   int r;
   int saved_num_empty_check;
@@ -1060,14 +1058,20 @@ compile_quant_body_with_empty_check(QuantNode* qn, regex_t* reg, ScanEnv* env)
     if (emptiness == BODY_MAY_BE_EMPTY)
       r = add_op(reg, OP_EMPTY_CHECK_END);
     else if (emptiness == BODY_MAY_BE_EMPTY_MEM) {
-      if (NODE_IS_EMPTY_STATUS_CHECK(qn) != 0)
+      if (NODE_IS_EMPTY_STATUS_CHECK(qn) != 0 && qn->empty_status_mem != 0) {
         r = add_op(reg, OP_EMPTY_CHECK_END_MEMST);
+        if (r != 0) return r;
+        COP(reg)->empty_check_end.empty_status_mem = qn->empty_status_mem;
+      }
       else
         r = add_op(reg, OP_EMPTY_CHECK_END);
     }
 #ifdef USE_CALL
-    else if (emptiness == BODY_MAY_BE_EMPTY_REC)
+    else if (emptiness == BODY_MAY_BE_EMPTY_REC) {
       r = add_op(reg, OP_EMPTY_CHECK_END_MEMST_PUSH);
+      if (r != 0) return r;
+      COP(reg)->empty_check_end.empty_status_mem = qn->empty_status_mem;
+    }
 #endif
 
     if (r != 0) return r;
@@ -1078,7 +1082,7 @@ compile_quant_body_with_empty_check(QuantNode* qn, regex_t* reg, ScanEnv* env)
 
 #ifdef USE_CALL
 static int
-compile_call(CallNode* node, regex_t* reg, ScanEnv* env)
+compile_call(CallNode* node, regex_t* reg, ParseEnv* env)
 {
   int r;
   int offset;
@@ -1098,7 +1102,7 @@ compile_call(CallNode* node, regex_t* reg, ScanEnv* env)
 #endif
 
 static int
-compile_tree_n_times(Node* node, int n, regex_t* reg, ScanEnv* env)
+compile_tree_n_times(Node* node, int n, regex_t* reg, ParseEnv* env)
 {
   int i, r;
 
@@ -1356,7 +1360,7 @@ entry_repeat_range(regex_t* reg, int id, int lower, int upper, int ops_index)
 
 static int
 compile_range_repeat_node(QuantNode* qn, int target_len, int emptiness,
-                          regex_t* reg, ScanEnv* env)
+                          regex_t* reg, ParseEnv* env)
 {
   int r;
   int num_repeat = reg->num_repeat++;
@@ -1469,7 +1473,7 @@ compile_length_quantifier_node(QuantNode* qn, regex_t* reg)
 }
 
 static int
-compile_quantifier_node(QuantNode* qn, regex_t* reg, ScanEnv* env)
+compile_quantifier_node(QuantNode* qn, regex_t* reg, ParseEnv* env)
 {
   int i, r, mod_tlen;
   int infinite = IS_INFINITE_REPEAT(qn->upper);
@@ -1649,7 +1653,7 @@ compile_length_option_node(BagNode* node, regex_t* reg)
 }
 
 static int
-compile_option_node(BagNode* node, regex_t* reg, ScanEnv* env)
+compile_option_node(BagNode* node, regex_t* reg, ParseEnv* env)
 {
   int r;
 
@@ -1765,7 +1769,7 @@ compile_length_bag_node(BagNode* node, regex_t* reg)
 }
 
 static int
-compile_bag_memory_node(BagNode* node, regex_t* reg, ScanEnv* env)
+compile_bag_memory_node(BagNode* node, regex_t* reg, ParseEnv* env)
 {
   int r;
 
@@ -1845,7 +1849,7 @@ compile_bag_memory_node(BagNode* node, regex_t* reg, ScanEnv* env)
 }
 
 static int
-compile_bag_node(BagNode* node, regex_t* reg, ScanEnv* env)
+compile_bag_node(BagNode* node, regex_t* reg, ParseEnv* env)
 {
   int r, len;
 
@@ -2036,7 +2040,7 @@ compile_length_anchor_node(AnchorNode* node, regex_t* reg)
 }
 
 static int
-compile_anchor_look_behind_node(AnchorNode* node, regex_t* reg, ScanEnv* env)
+compile_anchor_look_behind_node(AnchorNode* node, regex_t* reg, ParseEnv* env)
 {
   int r;
 
@@ -2150,7 +2154,7 @@ compile_anchor_look_behind_node(AnchorNode* node, regex_t* reg, ScanEnv* env)
 
 static int
 compile_anchor_look_behind_not_node(AnchorNode* node, regex_t* reg,
-                                    ScanEnv* env)
+                                    ParseEnv* env)
 {
   int r;
   int len;
@@ -2279,7 +2283,7 @@ compile_anchor_look_behind_not_node(AnchorNode* node, regex_t* reg,
 }
 
 static int
-compile_anchor_node(AnchorNode* node, regex_t* reg, ScanEnv* env)
+compile_anchor_node(AnchorNode* node, regex_t* reg, ParseEnv* env)
 {
   int r, len;
   enum OpCode op;
@@ -2573,7 +2577,7 @@ compile_length_tree(Node* node, regex_t* reg)
 }
 
 static int
-compile_tree(Node* node, regex_t* reg, ScanEnv* env)
+compile_tree(Node* node, regex_t* reg, ParseEnv* env)
 {
   int n, len, pos, r = 0;
 
@@ -2983,7 +2987,7 @@ numbered_ref_check(Node* node)
 }
 
 static int
-disable_noname_group_capture(Node** root, regex_t* reg, ScanEnv* env)
+disable_noname_group_capture(Node** root, regex_t* reg, ParseEnv* env)
 {
   int r, i, pos, counter;
   MemStatusType loc;
@@ -3003,7 +3007,7 @@ disable_noname_group_capture(Node** root, regex_t* reg, ScanEnv* env)
 
   for (i = 1, pos = 1; i <= env->num_mem; i++) {
     if (map[i].new_val > 0) {
-      SCANENV_MEMENV(env)[pos] = SCANENV_MEMENV(env)[i];
+      PARSEENV_MEMENV(env)[pos] = PARSEENV_MEMENV(env)[i];
       pos++;
     }
   }
@@ -3285,8 +3289,7 @@ get_tree_head_literal(Node* node, int exact, regex_t* reg)
       if (sn->end <= sn->s)
         break;
 
-      if (exact == 0 ||
-          ! NODE_IS_IGNORECASE(node) || NODE_STRING_IS_CRUDE(node)) {
+      if (exact == 0 || !NODE_IS_REAL_IGNORECASE(node)) {
         n = node;
       }
     }
@@ -3381,7 +3384,7 @@ get_tree_tail_literal(Node* node, Node** rnode, regex_t* reg)
         break;
       }
 
-      if (NODE_IS_IGNORECASE(node) && ! NODE_STRING_IS_CRUDE(node)) {
+      if (NODE_IS_REAL_IGNORECASE(node)) {
         r = GET_VALUE_NONE;
         break;
       }
@@ -3601,7 +3604,7 @@ check_node_in_look_behind(Node* node, int not, int* used)
 }
 
 static OnigLen
-node_min_byte_len(Node* node, ScanEnv* env)
+node_min_byte_len(Node* node, ParseEnv* env)
 {
   OnigLen len;
   OnigLen tmin;
@@ -3612,7 +3615,7 @@ node_min_byte_len(Node* node, ScanEnv* env)
     if (! NODE_IS_CHECKER(node)) {
       int i;
       int* backs;
-      MemEnv* mem_env = SCANENV_MEMENV(env);
+      MemEnv* mem_env = PARSEENV_MEMENV(env);
       BackRefNode* br = BACKREF_(node);
       if (NODE_IS_RECURSION(node)) break;
 
@@ -3629,10 +3632,8 @@ node_min_byte_len(Node* node, ScanEnv* env)
   case NODE_CALL:
     {
       Node* t = NODE_BODY(node);
-      if (NODE_IS_RECURSION(node)) {
-        if (NODE_IS_FIXED_MIN(t))
-          len = BAG_(t)->min_len;
-      }
+      if (NODE_IS_FIXED_MIN(t))
+        len = BAG_(t)->min_len;
       else
         len = node_min_byte_len(t, env);
     }
@@ -3742,143 +3743,8 @@ node_min_byte_len(Node* node, ScanEnv* env)
   return len;
 }
 
-static OnigLen
-node_max_byte_len(Node* node, ScanEnv* env)
-{
-  OnigLen len;
-  OnigLen tmax;
-
-  len = 0;
-  switch (NODE_TYPE(node)) {
-  case NODE_LIST:
-    do {
-      tmax = node_max_byte_len(NODE_CAR(node), env);
-      len = distance_add(len, tmax);
-    } while (IS_NOT_NULL(node = NODE_CDR(node)));
-    break;
-
-  case NODE_ALT:
-    do {
-      tmax = node_max_byte_len(NODE_CAR(node), env);
-      if (len < tmax) len = tmax;
-    } while (IS_NOT_NULL(node = NODE_CDR(node)));
-    break;
-
-  case NODE_STRING:
-    {
-      StrNode* sn = STR_(node);
-      len = (OnigLen )(sn->end - sn->s);
-    }
-    break;
-
-  case NODE_CTYPE:
-  case NODE_CCLASS:
-    len = ONIGENC_MBC_MAXLEN_DIST(env->enc);
-    break;
-
-  case NODE_BACKREF:
-    if (! NODE_IS_CHECKER(node)) {
-      int i;
-      int* backs;
-      MemEnv* mem_env = SCANENV_MEMENV(env);
-      BackRefNode* br = BACKREF_(node);
-      if (NODE_IS_RECURSION(node)) {
-#ifdef USE_BACKREF_WITH_LEVEL
-        if (NODE_IS_NEST_LEVEL(node)) {
-          len = INFINITE_LEN;
-        }
-#endif
-        break;
-      }
-      backs = BACKREFS_P(br);
-      for (i = 0; i < br->back_num; i++) {
-        tmax = node_max_byte_len(mem_env[backs[i]].mem_node, env);
-        if (len < tmax) len = tmax;
-      }
-    }
-    break;
-
-#ifdef USE_CALL
-  case NODE_CALL:
-    if (! NODE_IS_RECURSION(node))
-      len = node_max_byte_len(NODE_BODY(node), env);
-    else
-      len = INFINITE_LEN;
-    break;
-#endif
-
-  case NODE_QUANT:
-    {
-      QuantNode* qn = QUANT_(node);
-
-      if (qn->upper != 0) {
-        len = node_max_byte_len(NODE_BODY(node), env);
-        if (len != 0) {
-          if (! IS_INFINITE_REPEAT(qn->upper))
-            len = distance_multiply(len, qn->upper);
-          else
-            len = INFINITE_LEN;
-        }
-      }
-    }
-    break;
-
-  case NODE_BAG:
-    {
-      BagNode* en = BAG_(node);
-      switch (en->type) {
-      case BAG_MEMORY:
-        if (NODE_IS_FIXED_MAX(node))
-          len = en->max_len;
-        else {
-          if (NODE_IS_MARK1(node))
-            len = INFINITE_LEN;
-          else {
-            NODE_STATUS_ADD(node, MARK1);
-            len = node_max_byte_len(NODE_BODY(node), env);
-            NODE_STATUS_REMOVE(node, MARK1);
-
-            en->max_len = len;
-            NODE_STATUS_ADD(node, FIXED_MAX);
-          }
-        }
-        break;
-
-      case BAG_OPTION:
-      case BAG_STOP_BACKTRACK:
-        len = node_max_byte_len(NODE_BODY(node), env);
-        break;
-      case BAG_IF_ELSE:
-        {
-          OnigLen tlen, elen;
-
-          len = node_max_byte_len(NODE_BODY(node), env);
-          if (IS_NOT_NULL(en->te.Then)) {
-            tlen = node_max_byte_len(en->te.Then, env);
-            len = distance_add(len, tlen);
-          }
-          if (IS_NOT_NULL(en->te.Else))
-            elen = node_max_byte_len(en->te.Else, env);
-          else elen = 0;
-
-          if (elen > len) len = elen;
-        }
-        break;
-      }
-    }
-    break;
-
-  case NODE_ANCHOR:
-  case NODE_GIMMICK:
-  default:
-    break;
-  }
-
-  return len;
-}
-
 static int
-check_backrefs(Node* node, ScanEnv* env)
+check_backrefs(Node* node, ParseEnv* env)
 {
   int r;
 
@@ -3923,7 +3789,7 @@ check_backrefs(Node* node, ScanEnv* env)
       int i;
       BackRefNode* br = BACKREF_(node);
       int* backs = BACKREFS_P(br);
-      MemEnv* mem_env = SCANENV_MEMENV(env);
+      MemEnv* mem_env = PARSEENV_MEMENV(env);
 
       for (i = 0; i < br->back_num; i++) {
         if (backs[i] > env->num_mem)
@@ -3944,7 +3810,7 @@ check_backrefs(Node* node, ScanEnv* env)
 }
 
 static int
-set_empty_repeat_node_trav(Node* node, Node* empty, ScanEnv* env)
+set_empty_repeat_node_trav(Node* node, Node* empty, ParseEnv* env)
 {
   int r;
 
@@ -3998,7 +3864,7 @@ set_empty_repeat_node_trav(Node* node, Node* empty, ScanEnv* env)
       if (en->type == BAG_MEMORY) {
         if (NODE_IS_BACKREF(node)) {
           if (IS_NOT_NULL(empty))
-            SCANENV_MEMENV(env)[en->m.regnum].empty_repeat_node = empty;
+            PARSEENV_MEMENV(env)[en->m.regnum].empty_repeat_node = empty;
         }
       }
       else if (en->type == BAG_IF_ELSE) {
@@ -4034,7 +3900,7 @@ is_ancestor_node(Node* node, Node* me)
 }
 
 static void
-set_empty_status_check_trav(Node* node, ScanEnv* env)
+set_empty_status_check_trav(Node* node, ParseEnv* env)
 {
   switch (NODE_TYPE(node)) {
   case NODE_LIST:
@@ -4078,14 +3944,14 @@ set_empty_status_check_trav(Node* node, ScanEnv* env)
     {
       int i;
       int* backs;
-      MemEnv* mem_env = SCANENV_MEMENV(env);
+      MemEnv* mem_env = PARSEENV_MEMENV(env);
       BackRefNode* br = BACKREF_(node);
       backs = BACKREFS_P(br);
       for (i = 0; i < br->back_num; i++) {
         Node* ernode = mem_env[backs[i]].empty_repeat_node;
         if (IS_NOT_NULL(ernode)) {
           if (! is_ancestor_node(ernode, node)) {
-            MEM_STATUS_LIMIT_ON(env->reg->empty_status_mem, backs[i]);
+            MEM_STATUS_LIMIT_ON(QUANT_(ernode)->empty_status_mem, backs[i]);
             NODE_STATUS_ADD(ernode, EMPTY_STATUS_CHECK);
             NODE_STATUS_ADD(mem_env[backs[i]].mem_node, EMPTY_STATUS_CHECK);
           }
@@ -4150,7 +4016,7 @@ set_parent_node_trav(Node* node, Node* parent)
 #define RECURSION_INFINITE     (1<<2)
 
 static int
-infinite_recursive_call_check(Node* node, ScanEnv* env, int head)
+infinite_recursive_call_check(Node* node, ParseEnv* env, int head)
 {
   int ret;
   int r = 0;
@@ -4191,6 +4057,8 @@ infinite_recursive_call_check(Node* node, ScanEnv* env, int head)
     break;
 
   case NODE_QUANT:
+    if (QUANT_(node)->upper == 0) break;
+
     r = infinite_recursive_call_check(NODE_BODY(node), env, head);
     if (r < 0) return r;
     if ((r & RECURSION_MUST) != 0) {
@@ -4265,7 +4133,7 @@ infinite_recursive_call_check(Node* node, ScanEnv* env, int head)
 }
 
 static int
-infinite_recursive_call_check_trav(Node* node, ScanEnv* env)
+infinite_recursive_call_check_trav(Node* node, ParseEnv* env)
 {
   int r;
 
@@ -4403,7 +4271,7 @@ recursive_call_check(Node* node)
 #define FOUND_CALLED_NODE    1
 
 static int
-recursive_call_check_trav(Node* node, ScanEnv* env, int state)
+recursive_call_check_trav(Node* node, ParseEnv* env, int state)
 {
   int r = 0;
 
@@ -4443,19 +4311,21 @@ recursive_call_check_trav(Node* node, ScanEnv* env, int state)
       BagNode* en = BAG_(node);
 
       if (en->type == BAG_MEMORY) {
-        if (NODE_IS_CALLED(node) || (state & IN_RECURSION) != 0) {
+        if (NODE_IS_CALLED(node)) {
+          r = FOUND_CALLED_NODE;
+          goto check_recursion;
+        }
+        else if ((state & IN_RECURSION) != 0) {
+        check_recursion:
           if (! NODE_IS_RECURSION(node)) {
             NODE_STATUS_ADD(node, MARK1);
-            r = recursive_call_check(NODE_BODY(node));
-            if (r != 0) {
+            ret = recursive_call_check(NODE_BODY(node));
+            if (ret != 0) {
               NODE_STATUS_ADD(node, RECURSION);
               MEM_STATUS_ON(env->backtrack_mem, en->m.regnum);
             }
             NODE_STATUS_REMOVE(node, MARK1);
           }
-
-          if (NODE_IS_CALLED(node))
-            r = FOUND_CALLED_NODE;
         }
       }
 
@@ -4616,8 +4486,9 @@ reduce_string_list(Node* node, OnigEncoding enc)
 #define IN_VAR_REPEAT   (1<<3)
 #define IN_ZERO_REPEAT  (1<<4)
 #define IN_MULTI_ENTRY  (1<<5)
-#define IN_LOOK_BEHIND  (1<<6)
-
+#define IN_PREC_READ    (1<<6)
+#define IN_LOOK_BEHIND  (1<<7)
+#define IN_PEEK         (1<<8)
 
 /* divide different length alternatives in look-behind.
   (?<=A|B) ==> (?<=A)|(?<=B)
@@ -4706,7 +4577,7 @@ list_reduce_in_look_behind(Node* node)
 }
 
 static int
-alt_reduce_in_look_behind(Node* node, regex_t* reg, ScanEnv* env)
+alt_reduce_in_look_behind(Node* node, regex_t* reg, ParseEnv* env)
 {
   int r;
 
@@ -4725,10 +4596,10 @@ alt_reduce_in_look_behind(Node* node, regex_t* reg, ScanEnv* env)
   return r;
 }
 
-static int tune_tree(Node* node, regex_t* reg, int state, ScanEnv* env);
+static int tune_tree(Node* node, regex_t* reg, int state, ParseEnv* env);
 
 static int
-tune_look_behind(Node* node, regex_t* reg, int state, ScanEnv* env)
+tune_look_behind(Node* node, regex_t* reg, int state, ParseEnv* env)
 {
   int r;
   int state1;
@@ -5183,7 +5054,7 @@ unravel_case_fold_string(Node* node, regex_t* reg, int state)
   return r;
 }
 
-#ifdef USE_STUBBORN_CHECK_CAPTURES_IN_EMPTY_REPEAT
+#ifdef USE_RIGID_CHECK_CAPTURES_IN_EMPTY_REPEAT
 static enum BodyEmptyType
 quantifiers_memory_node_info(Node* node)
 {
@@ -5265,7 +5136,7 @@ quantifiers_memory_node_info(Node* node)
 
   return r;
 }
-#endif /* USE_STUBBORN_CHECK_CAPTURES_IN_EMPTY_REPEAT */
+#endif /* USE_RIGID_CHECK_CAPTURES_IN_EMPTY_REPEAT */
 
 
 #ifdef USE_CALL
@@ -5274,9 +5145,9 @@ quantifiers_memory_node_info(Node* node)
 __inline
 #endif
 static int
-check_call_reference(CallNode* cn, ScanEnv* env, int state)
+check_call_reference(CallNode* cn, ParseEnv* env, int state)
 {
-  MemEnv* mem_env = SCANENV_MEMENV(env);
+  MemEnv* mem_env = PARSEENV_MEMENV(env);
 
   if (cn->by_number != 0) {
     int gnum = cn->called_gnum;
@@ -5393,7 +5264,7 @@ tune_call2_call(Node* node)
 }
 
 static int
-tune_call(Node* node, ScanEnv* env, int state)
+tune_call(Node* node, ParseEnv* env, int state)
 {
   int r;
 
@@ -5539,6 +5410,8 @@ tune_called_state_call(Node* node, int state)
         state |= IN_REAL_REPEAT;
       if (qn->lower != qn->upper)
         state |= IN_VAR_REPEAT;
+      if ((state & IN_PEEK) != 0)
+        NODE_STATUS_ADD(node, INPEEK);
 
       tune_called_state_call(NODE_QUANT_BODY(qn), state);
     }
@@ -5551,10 +5424,12 @@ tune_called_state_call(Node* node, int state)
       switch (an->type) {
       case ANCR_PREC_READ_NOT:
       case ANCR_LOOK_BEHIND_NOT:
-        state |= IN_NOT;
-        /* fall */
+        state |= (IN_NOT | IN_PEEK);
+        tune_called_state_call(NODE_ANCHOR_BODY(an), state);
+        break;
       case ANCR_PREC_READ:
       case ANCR_LOOK_BEHIND:
+        state |= IN_PEEK;
         tune_called_state_call(NODE_ANCHOR_BODY(an), state);
         break;
       default:
@@ -5597,6 +5472,11 @@ tune_called_state_call(Node* node, int state)
     break;
 
   case NODE_CALL:
+    if ((state & IN_PEEK) != 0)
+      NODE_STATUS_ADD(node, INPEEK);
+    if ((state & IN_REAL_REPEAT) != 0)
+      NODE_STATUS_ADD(node, IN_REAL_REPEAT);
+
     tune_called_state_call(NODE_BODY(node), state);
     break;
 
@@ -5620,6 +5500,11 @@ tune_called_state(Node* node, int state)
 
 #ifdef USE_CALL
   case NODE_CALL:
+    if ((state & IN_PEEK) != 0)
+      NODE_STATUS_ADD(node, INPEEK);
+    if ((state & IN_REAL_REPEAT) != 0)
+      NODE_STATUS_ADD(node, IN_REAL_REPEAT);
+
     tune_called_state_call(node, state);
     break;
 #endif
@@ -5659,6 +5544,8 @@ tune_called_state(Node* node, int state)
         state |= IN_REAL_REPEAT;
       if (qn->lower != qn->upper)
         state |= IN_VAR_REPEAT;
+      if ((state & IN_PEEK) != 0)
+        NODE_STATUS_ADD(node, INPEEK);
 
       tune_called_state(NODE_QUANT_BODY(qn), state);
     }
@@ -5671,10 +5558,12 @@ tune_called_state(Node* node, int state)
       switch (an->type) {
       case ANCR_PREC_READ_NOT:
       case ANCR_LOOK_BEHIND_NOT:
-        state |= IN_NOT;
-        /* fall */
+        state |= (IN_NOT | IN_PEEK);
+        tune_called_state(NODE_ANCHOR_BODY(an), state);
+        break;
       case ANCR_PREC_READ:
       case ANCR_LOOK_BEHIND:
+        state |= IN_PEEK;
         tune_called_state(NODE_ANCHOR_BODY(an), state);
         break;
       default:
@@ -5700,17 +5589,18 @@ tune_called_state(Node* node, int state)
 __inline
 #endif
 static int
-tune_anchor(Node* node, regex_t* reg, int state, ScanEnv* env)
+tune_anchor(Node* node, regex_t* reg, int state, ParseEnv* env)
 {
   int r;
   AnchorNode* an = ANCHOR_(node);
 
   switch (an->type) {
   case ANCR_PREC_READ:
-    r = tune_tree(NODE_ANCHOR_BODY(an), reg, state, env);
+    r = tune_tree(NODE_ANCHOR_BODY(an), reg, (state | IN_PREC_READ), env);
     break;
   case ANCR_PREC_READ_NOT:
-    r = tune_tree(NODE_ANCHOR_BODY(an), reg, (state | IN_NOT), env);
+    r = tune_tree(NODE_ANCHOR_BODY(an), reg, (state | IN_PREC_READ | IN_NOT),
+                  env);
     break;
 
   case ANCR_LOOK_BEHIND:
@@ -5730,7 +5620,7 @@ tune_anchor(Node* node, regex_t* reg, int state, ScanEnv* env)
 __inline
 #endif
 static int
-tune_quant(Node* node, regex_t* reg, int state, ScanEnv* env)
+tune_quant(Node* node, regex_t* reg, int state, ParseEnv* env)
 {
   int r;
   QuantNode* qn = QUANT_(node);
@@ -5746,7 +5636,7 @@ tune_quant(Node* node, regex_t* reg, int state, ScanEnv* env)
   if (IS_INFINITE_REPEAT(qn->upper) || qn->upper >= 1) {
     OnigLen d = node_min_byte_len(body, env);
     if (d == 0) {
-#ifdef USE_STUBBORN_CHECK_CAPTURES_IN_EMPTY_REPEAT
+#ifdef USE_RIGID_CHECK_CAPTURES_IN_EMPTY_REPEAT
       qn->emptiness = quantifiers_memory_node_info(body);
 #else
       qn->emptiness = BODY_MAY_BE_EMPTY;
@@ -5807,7 +5697,7 @@ tune_quant(Node* node, regex_t* reg, int state, ScanEnv* env)
  6. expand repeated string.
  */
 static int
-tune_tree(Node* node, regex_t* reg, int state, ScanEnv* env)
+tune_tree(Node* node, regex_t* reg, int state, ParseEnv* env)
 {
   int r = 0;
 
@@ -5832,7 +5722,7 @@ tune_tree(Node* node, regex_t* reg, int state, ScanEnv* env)
     break;
 
   case NODE_STRING:
-    if (NODE_IS_IGNORECASE(node) && ! NODE_STRING_IS_CRUDE(node)) {
+    if (NODE_IS_REAL_IGNORECASE(node)) {
       r = unravel_case_fold_string(node, reg, state);
     }
     break;
@@ -5918,6 +5808,9 @@ tune_tree(Node* node, regex_t* reg, int state, ScanEnv* env)
     break;
 
   case NODE_QUANT:
+    if ((state & (IN_PREC_READ | IN_LOOK_BEHIND)) != 0)
+      NODE_STATUS_ADD(node, INPEEK);
+
     r = tune_quant(node, reg, state, env);
     break;
 
@@ -5938,6 +5831,7 @@ tune_tree(Node* node, regex_t* reg, int state, ScanEnv* env)
   return r;
 }
 
+#ifndef ONIG_DONT_OPTIMIZE
 static int
 set_sunday_quick_search_or_bmh_skip_table(regex_t* reg, int case_expand,
                                           UChar* s, UChar* end,
@@ -6007,6 +5901,7 @@ set_sunday_quick_search_or_bmh_skip_table(regex_t* reg, int case_expand,
 
   return 0;
 }
+#endif
 
 
 #define OPT_EXACT_MAXLEN   24
@@ -6019,7 +5914,7 @@ typedef struct {
   MinMaxLen        mm;
   OnigEncoding     enc;
   OnigCaseFoldType case_fold_flag;
-  ScanEnv*         scan_env;
+  ParseEnv*        scan_env;
 } OptEnv;
 
 typedef struct {
@@ -6052,6 +5947,8 @@ typedef struct {
 } OptNode;
 
 
+#ifndef ONIG_DONT_OPTIMIZE
+
 static int
 map_position_value(OnigEncoding enc, int i)
 {
@@ -6540,6 +6437,140 @@ alt_merge_node_opt_info(OptNode* to, OptNode* add, OptEnv* env)
   mml_alt_merge(&to->len, &add->len);
 }
 
+static OnigLen
+node_max_byte_len(Node* node, ParseEnv* env)
+{
+  OnigLen len;
+  OnigLen tmax;
+
+  len = 0;
+  switch (NODE_TYPE(node)) {
+  case NODE_LIST:
+    do {
+      tmax = node_max_byte_len(NODE_CAR(node), env);
+      len = distance_add(len, tmax);
+    } while (IS_NOT_NULL(node = NODE_CDR(node)));
+    break;
+
+  case NODE_ALT:
+    do {
+      tmax = node_max_byte_len(NODE_CAR(node), env);
+      if (len < tmax) len = tmax;
+    } while (IS_NOT_NULL(node = NODE_CDR(node)));
+    break;
+
+  case NODE_STRING:
+    {
+      StrNode* sn = STR_(node);
+      len = (OnigLen )(sn->end - sn->s);
+    }
+    break;
+
+  case NODE_CTYPE:
+  case NODE_CCLASS:
+    len = ONIGENC_MBC_MAXLEN_DIST(env->enc);
+    break;
+
+  case NODE_BACKREF:
+    if (! NODE_IS_CHECKER(node)) {
+      int i;
+      int* backs;
+      MemEnv* mem_env = PARSEENV_MEMENV(env);
+      BackRefNode* br = BACKREF_(node);
+      if (NODE_IS_RECURSION(node)) {
+#ifdef USE_BACKREF_WITH_LEVEL
+        if (NODE_IS_NEST_LEVEL(node)) {
+          len = INFINITE_LEN;
+        }
+#endif
+        break;
+      }
+      backs = BACKREFS_P(br);
+      for (i = 0; i < br->back_num; i++) {
+        tmax = node_max_byte_len(mem_env[backs[i]].mem_node, env);
+        if (len < tmax) len = tmax;
+      }
+    }
+    break;
+
+#ifdef USE_CALL
+  case NODE_CALL:
+    if (! NODE_IS_RECURSION(node))
+      len = node_max_byte_len(NODE_BODY(node), env);
+    else
+      len = INFINITE_LEN;
+    break;
+#endif
+
+  case NODE_QUANT:
+    {
+      QuantNode* qn = QUANT_(node);
+
+      if (qn->upper != 0) {
+        len = node_max_byte_len(NODE_BODY(node), env);
+        if (len != 0) {
+          if (! IS_INFINITE_REPEAT(qn->upper))
+            len = distance_multiply(len, qn->upper);
+          else
+            len = INFINITE_LEN;
+        }
+      }
+    }
+    break;
+
+  case NODE_BAG:
+    {
+      BagNode* en = BAG_(node);
+      switch (en->type) {
+      case BAG_MEMORY:
+        if (NODE_IS_FIXED_MAX(node))
+          len = en->max_len;
+        else {
+          if (NODE_IS_MARK1(node))
+            len = INFINITE_LEN;
+          else {
+            NODE_STATUS_ADD(node, MARK1);
+            len = node_max_byte_len(NODE_BODY(node), env);
+            NODE_STATUS_REMOVE(node, MARK1);
+
+            en->max_len = len;
+            NODE_STATUS_ADD(node, FIXED_MAX);
+          }
+        }
+        break;
+
+      case BAG_OPTION:
+      case BAG_STOP_BACKTRACK:
+        len = node_max_byte_len(NODE_BODY(node), env);
+        break;
+      case BAG_IF_ELSE:
+        {
+          OnigLen tlen, elen;
+
+          len = node_max_byte_len(NODE_BODY(node), env);
+          if (IS_NOT_NULL(en->te.Then)) {
+            tlen = node_max_byte_len(en->te.Then, env);
+            len = distance_add(len, tlen);
+          }
+          if (IS_NOT_NULL(en->te.Else))
+            elen = node_max_byte_len(en->te.Else, env);
+          else elen = 0;
+
+          if (elen > len) len = elen;
+        }
+        break;
+      }
+    }
+    break;
+
+  case NODE_ANCHOR:
+  case NODE_GIMMICK:
+  default:
+    break;
+  }
+
+  return len;
+}
 
 #define MAX_NODE_OPT_INFO_REF_COUNT    5
 
@@ -6822,22 +6853,22 @@ optimize_nodes(Node* node, OptNode* opt, OptEnv* env)
         {
           OptEnv nenv;
 
-          copy_opt_env(&nenv, env);
-          r = optimize_nodes(NODE_BAG_BODY(en), &xo, &nenv);
-          if (r == 0) {
-            mml_add(&nenv.mm, &xo.len);
-            concat_left_node_opt_info(enc, opt, &xo);
-            if (IS_NOT_NULL(en->te.Then)) {
-              r = optimize_nodes(en->te.Then, &xo, &nenv);
-              if (r == 0) {
-                concat_left_node_opt_info(enc, opt, &xo);
+          if (IS_NOT_NULL(en->te.Else)) {
+            copy_opt_env(&nenv, env);
+            r = optimize_nodes(NODE_BAG_BODY(en), &xo, &nenv);
+            if (r == 0) {
+              mml_add(&nenv.mm, &xo.len);
+              concat_left_node_opt_info(enc, opt, &xo);
+              if (IS_NOT_NULL(en->te.Then)) {
+                r = optimize_nodes(en->te.Then, &xo, &nenv);
+                if (r == 0) {
+                  concat_left_node_opt_info(enc, opt, &xo);
+                }
               }
-            }
 
-            if (IS_NOT_NULL(en->te.Else)) {
-              r = optimize_nodes(en->te.Else, &xo, env);
-              if (r == 0)
-                alt_merge_node_opt_info(opt, &xo, env);
+                r = optimize_nodes(en->te.Else, &xo, env);
+                if (r == 0)
+                  alt_merge_node_opt_info(opt, &xo, env);
             }
           }
         }
@@ -6930,7 +6961,7 @@ static void print_optimize_info(FILE* f, regex_t* reg);
 #endif
 
 static int
-set_optimize_info_from_tree(Node* node, regex_t* reg, ScanEnv* scan_env)
+set_optimize_info_from_tree(Node* node, regex_t* reg, ParseEnv* scan_env)
 {
   int r;
   OptNode opt;
@@ -6985,6 +7016,7 @@ set_optimize_info_from_tree(Node* node, regex_t* reg, ScanEnv* scan_env)
 #endif
   return r;
 }
+#endif /* ONIG_DONT_OPTIMIZE */
 
 static void
 clear_optimize_info(regex_t* reg)
@@ -7031,14 +7063,43 @@ static void print_enc_string(FILE* fp, OnigEncoding enc,
       s++;
     }
   }
+}
 
-  fprintf(fp, "/\n");
+static void
+print_options(FILE* fp, OnigOptionType o)
+{
+  if ((o & ONIG_OPTION_IGNORECASE) != 0)      fprintf(fp, " IGNORECASE");
+  if ((o & ONIG_OPTION_EXTEND) != 0)          fprintf(fp, " EXTEND");
+  if ((o & ONIG_OPTION_MULTILINE) != 0)       fprintf(fp, " MULTILINE");
+  if ((o & ONIG_OPTION_SINGLELINE) != 0)      fprintf(fp, " SINGLELINE");
+  if ((o & ONIG_OPTION_FIND_LONGEST) != 0)    fprintf(fp, " FIND_LONGEST");
+  if ((o & ONIG_OPTION_FIND_NOT_EMPTY) != 0)  fprintf(fp, " FIND_NOT_EMPTY");
+  if ((o & ONIG_OPTION_NEGATE_SINGLELINE) != 0)  fprintf(fp, " NEGATE_SINGLELINE");
+  if ((o & ONIG_OPTION_DONT_CAPTURE_GROUP) != 0) fprintf(fp, " DONT_CAPTURE_GROUP");
+  if ((o & ONIG_OPTION_CAPTURE_GROUP) != 0)   fprintf(fp, " CAPTURE_GROUP");
+  if ((o & ONIG_OPTION_NOTBOL) != 0)          fprintf(fp, " NOTBOL");
+  if ((o & ONIG_OPTION_NOTEOL) != 0)          fprintf(fp, " NOTEOL");
+  if ((o & ONIG_OPTION_POSIX_REGION) != 0)    fprintf(fp, " POSIX_REGION");
+  if ((o & ONIG_OPTION_CHECK_VALIDITY_OF_STRING) != 0) fprintf(fp, " CHECK_VALIDITY_OF_STRING");
+  if ((o & ONIG_OPTION_IGNORECASE_IS_ASCII) != 0) fprintf(fp, " IGNORECASE_IS_ASCII");
+  if ((o & ONIG_OPTION_WORD_IS_ASCII) != 0)   fprintf(fp, " WORD_IS_ASCII");
+  if ((o & ONIG_OPTION_DIGIT_IS_ASCII) != 0)  fprintf(fp, " DIGIT_IS_ASCII");
+  if ((o & ONIG_OPTION_SPACE_IS_ASCII) != 0)  fprintf(fp, " SPACE_IS_ASCII");
+  if ((o & ONIG_OPTION_POSIX_IS_ASCII) != 0)  fprintf(fp, " POSIX_IS_ASCII");
+  if ((o & ONIG_OPTION_TEXT_SEGMENT_EXTENDED_GRAPHEME_CLUSTER) != 0) fprintf(fp, " TEXT_SEGMENT_EXTENDED_GRAPHEME_CLUSTER");
+  if ((o & ONIG_OPTION_TEXT_SEGMENT_WORD) != 0) fprintf(fp, " TEXT_SEGMENT_WORD");
+  if ((o & ONIG_OPTION_NOT_BEGIN_STRING) != 0) fprintf(fp, " NOT_BIGIN_STRING");
+  if ((o & ONIG_OPTION_NOT_END_STRING) != 0)   fprintf(fp, " NOT_END_STRING");
+  if ((o & ONIG_OPTION_NOT_BEGIN_POSITION) != 0) fprintf(fp, " NOT_BEGIN_POSITION");
+  if ((o & ONIG_OPTION_CALLBACK_EACH_MATCH) != 0) fprintf(fp, " CALLBACK_EACH_MATCH");
 }
 
 #endif /* ONIG_DEBUG */
 
 #if defined(ONIG_DEBUG_COMPILE) || defined(ONIG_DEBUG_MATCH)
 
+#ifndef ONIG_DONT_OPTIMIZE
+
 static void
 print_distance_range(FILE* f, OnigLen a, OnigLen b)
 {
@@ -7161,7 +7222,8 @@ print_optimize_info(FILE* f, regex_t* reg)
     }
   }
 }
-#endif
+#endif /* ONIG_DONT_OPTIMIZE */
+#endif /* defined(ONIG_DEBUG_COMPILE) || defined(ONIG_DEBUG_MATCH) */
 
 
 extern RegexExt*
@@ -7259,93 +7321,150 @@ static void print_tree P_((FILE* f, Node* node));
 
 extern int onig_init_for_match_at(regex_t* reg);
 
-extern int
-onig_compile(regex_t* reg, const UChar* pattern, const UChar* pattern_end,
-             OnigErrorInfo* einfo)
-{
-  int r;
-  Node*  root;
-  ScanEnv  scan_env;
+static int parse_and_tune(regex_t* reg, const UChar* pattern,
+  const UChar* pattern_end, ParseEnv *scan_env, Node** rroot,
+  OnigErrorInfo* einfo
 #ifdef USE_CALL
-  UnsetAddrList  uslist = {0};
+  , UnsetAddrList* uslist
 #endif
+)
+{
+  int r;
+  Node* root;
 
-  root = 0;
+  root = NULL_NODE;
   if (IS_NOT_NULL(einfo)) {
     einfo->enc = reg->enc;
     einfo->par = (UChar* )NULL;
   }
 
-#ifdef ONIG_DEBUG
-  fprintf(DBGFP, "\nPATTERN: /");
-  print_enc_string(DBGFP, reg->enc, pattern, pattern_end);
-#endif
-
-  if (reg->ops_alloc == 0) {
-    r = ops_init(reg, OPS_INIT_SIZE);
-    if (r != 0) goto end;
-  }
-  else
-    reg->ops_used = 0;
-
-  r = onig_parse_tree(&root, pattern, pattern_end, reg, &scan_env);
+  r = onig_parse_tree(&root, pattern, pattern_end, reg, scan_env);
   if (r != 0) goto err;
 
   r = reduce_string_list(root, reg->enc);
   if (r != 0) goto err;
 
   /* mixed use named group and no-named group */
-  if (scan_env.num_named > 0 &&
-      IS_SYNTAX_BV(scan_env.syntax, ONIG_SYN_CAPTURE_ONLY_NAMED_GROUP) &&
+  if (scan_env->num_named > 0 &&
+      IS_SYNTAX_BV(scan_env->syntax, ONIG_SYN_CAPTURE_ONLY_NAMED_GROUP) &&
       ! OPTON_CAPTURE_GROUP(reg->options)) {
-    if (scan_env.num_named != scan_env.num_mem)
-      r = disable_noname_group_capture(&root, reg, &scan_env);
+    if (scan_env->num_named != scan_env->num_mem)
+      r = disable_noname_group_capture(&root, reg, scan_env);
     else
       r = numbered_ref_check(root);
 
     if (r != 0) goto err;
   }
 
-  r = check_backrefs(root, &scan_env);
+  r = check_backrefs(root, scan_env);
   if (r != 0) goto err;
 
 #ifdef USE_CALL
-  if (scan_env.num_call > 0) {
-    r = unset_addr_list_init(&uslist, scan_env.num_call);
+  if (scan_env->num_call > 0) {
+    r = unset_addr_list_init(uslist, scan_env->num_call);
     if (r != 0) goto err;
-    scan_env.unset_addr_list = &uslist;
-    r = tune_call(root, &scan_env, 0);
+    scan_env->unset_addr_list = uslist;
+    r = tune_call(root, scan_env, 0);
     if (r != 0) goto err_unset;
     r = tune_call2(root);
     if (r != 0) goto err_unset;
-    r = recursive_call_check_trav(root, &scan_env, 0);
+    r = recursive_call_check_trav(root, scan_env, 0);
     if (r  < 0) goto err_unset;
-    r = infinite_recursive_call_check_trav(root, &scan_env);
+    r = infinite_recursive_call_check_trav(root, scan_env);
     if (r != 0) goto err_unset;
 
     tune_called_state(root, 0);
   }
 
-  reg->num_call = scan_env.num_call;
+  reg->num_call = scan_env->num_call;
 #endif
 
 #ifdef ONIG_DEBUG_PARSE
-  fprintf(DBGFP, "MAX PARSE DEPTH: %d\n", scan_env.max_parse_depth);
-  fprintf(DBGFP, "TREE (parsed)\n");
-  print_tree(DBGFP, root);
-  fprintf(DBGFP, "\n");
+  fprintf(DBGFP, "MAX PARSE DEPTH: %d\n", scan_env->max_parse_depth);
 #endif
 
-  r = tune_tree(root, reg, 0, &scan_env);
-  if (r != 0) goto err_unset;
+  r = tune_tree(root, reg, 0, scan_env);
+  if (r != 0) {
+#ifdef ONIG_DEBUG_PARSE
+    fprintf(DBGFP, "TREE (error in tune)\n");
+    print_tree(DBGFP, root);
+    fprintf(DBGFP, "\n");
+#endif
+    goto err_unset;
+  }
 
-  if (scan_env.backref_num != 0) {
+  if (scan_env->backref_num != 0) {
     set_parent_node_trav(root, NULL_NODE);
-    r = set_empty_repeat_node_trav(root, NULL_NODE, &scan_env);
+    r = set_empty_repeat_node_trav(root, NULL_NODE, scan_env);
     if (r != 0) goto err_unset;
-    set_empty_status_check_trav(root, &scan_env);
+    set_empty_status_check_trav(root, scan_env);
   }
 
+  *rroot = root;
+  return r;
+
+ err_unset:
+#ifdef USE_CALL
+  if (scan_env->num_call > 0) {
+    unset_addr_list_end(uslist);
+  }
+#endif
+ err:
+  if (IS_NOT_NULL(scan_env->error)) {
+    if (IS_NOT_NULL(einfo)) {
+      einfo->par     = scan_env->error;
+      einfo->par_end = scan_env->error_end;
+    }
+  }
+
+  onig_node_free(root);
+  if (IS_NOT_NULL(scan_env->mem_env_dynamic))
+    xfree(scan_env->mem_env_dynamic);
+
+  *rroot = NULL_NODE;
+  return r;
+}
+
+extern int
+onig_compile(regex_t* reg, const UChar* pattern, const UChar* pattern_end,
+             OnigErrorInfo* einfo)
+{
+  int r;
+  Node* root;
+  ParseEnv scan_env;
+#ifdef USE_CALL
+  UnsetAddrList uslist = {0};
+#endif
+
+#ifdef ONIG_DEBUG
+  fprintf(DBGFP, "\nPATTERN: /");
+  print_enc_string(DBGFP, reg->enc, pattern, pattern_end);
+  fprintf(DBGFP, "/\n");
+  fprintf(DBGFP, "OPTIONS:");
+  print_options(DBGFP, reg->options);
+  fprintf(DBGFP, "\n");
+#endif
+
+  if (reg->ops_alloc == 0) {
+    r = ops_init(reg, OPS_INIT_SIZE);
+    if (r != 0) {
+      if (IS_NOT_NULL(einfo)) {
+        einfo->enc = reg->enc;
+        einfo->par = (UChar* )NULL;
+      }
+      return r;
+    }
+  }
+  else
+    reg->ops_used = 0;
+
+  r = parse_and_tune(reg, pattern, pattern_end, &scan_env, &root, einfo
+#ifdef USE_CALL
+                     , &uslist
+#endif
+                    );
+  if (r != 0) return r;
+
 #ifdef ONIG_DEBUG_PARSE
   fprintf(DBGFP, "TREE (after tune)\n");
   print_tree(DBGFP, root);
@@ -7377,7 +7496,14 @@ onig_compile(regex_t* reg, const UChar* pattern, const UChar* pattern_end,
   clear_optimize_info(reg);
 #ifndef ONIG_DONT_OPTIMIZE
   r = set_optimize_info_from_tree(root, reg, &scan_env);
-  if (r != 0) goto err_unset;
+  if (r != 0)  {
+#ifdef USE_CALL
+    if (scan_env.num_call > 0) {
+      unset_addr_list_end(&uslist);
+    }
+#endif
+    goto err;
+  }
 #endif
 
   if (IS_NOT_NULL(scan_env.mem_env_dynamic)) {
@@ -7407,6 +7533,9 @@ onig_compile(regex_t* reg, const UChar* pattern, const UChar* pattern_end,
     }
 #endif
 
+    r = ops_resize(reg, reg->ops_used);
+    if (r != ONIG_NORMAL) goto err;
+
     set_addr_in_repeat_range(reg);
 
     if ((reg->push_mem_end != 0)
@@ -7449,15 +7578,8 @@ onig_compile(regex_t* reg, const UChar* pattern, const UChar* pattern_end,
   onig_init_for_match_at(reg);
 #endif
 
- end:
   return r;
 
- err_unset:
-#ifdef USE_CALL
-  if (scan_env.num_call > 0) {
-    unset_addr_list_end(&uslist);
-  }
-#endif
  err:
   if (IS_NOT_NULL(scan_env.error)) {
     if (IS_NOT_NULL(einfo)) {
@@ -7513,6 +7635,12 @@ onig_reg_init(regex_t* reg, OnigOptionType option, OnigCaseFoldType case_fold_fl
   else
     option |= syntax->options;
 
+  if ((option & ONIG_OPTION_IGNORECASE_IS_ASCII) != 0) {
+    case_fold_flag &= ~(INTERNAL_ONIGENC_CASE_FOLD_MULTI_CHAR |
+                        ONIGENC_CASE_FOLD_TURKISH_AZERI);
+    case_fold_flag |= ONIGENC_CASE_FOLD_ASCII_ONLY;
+  }
+
   (reg)->enc            = enc;
   (reg)->options        = option;
   (reg)->syntax         = syntax;
@@ -7703,15 +7831,145 @@ onig_is_code_in_cc(OnigEncoding enc, OnigCodePoint code, CClassNode* cc)
   return onig_is_code_in_cc_len(len, code, cc);
 }
 
+
+#define MANY_REPEAT_OF_ANYCHAR   20
+
+typedef enum {
+  MJ_NO     = 0,
+  MJ_YES    = 1,
+  MJ_IGNORE = 2,
+} MJ_RESULT;
+
+static MJ_RESULT
+mostly_just_anychar(Node* node, int in_reluctant)
+{
+  MJ_RESULT r;
+
+  r = MJ_NO;
+  switch (NODE_TYPE(node)) {
+  case NODE_LIST:
+    {
+      int found = FALSE;
+      do {
+        r = mostly_just_anychar(NODE_CAR(node), in_reluctant);
+        if (r == MJ_NO) break;
+        if (r == MJ_YES) found = TRUE;
+      } while (IS_NOT_NULL(node = NODE_CDR(node)));
+      if (r == MJ_IGNORE) {
+        if (found == TRUE) r = MJ_YES;
+      }
+    }
+    break;
+
+  case NODE_ALT:
+    r = MJ_IGNORE;
+    do {
+      r = mostly_just_anychar(NODE_CAR(node), in_reluctant);
+      if (r == MJ_YES) break;
+    } while (IS_NOT_NULL(node = NODE_CDR(node)));
+    break;
+
+  case NODE_QUANT:
+    {
+      QuantNode* qn = QUANT_(node);
+
+      if (qn->upper == 0)
+        r = MJ_IGNORE;
+      else {
+        if (in_reluctant == FALSE) {
+          if (qn->greedy != 0 &&
+              (! IS_INFINITE_REPEAT(qn->upper) &&
+               qn->upper <= MANY_REPEAT_OF_ANYCHAR)) {
+            in_reluctant = TRUE;
+          }
+        }
+        r = mostly_just_anychar(NODE_BODY(node), in_reluctant);
+      }
+    }
+    break;
+
+  case NODE_ANCHOR:
+    switch (ANCHOR_(node)->type) {
+    case ANCR_PREC_READ:
+    case ANCR_PREC_READ_NOT:
+    case ANCR_LOOK_BEHIND:
+    case ANCR_LOOK_BEHIND_NOT:
+    case ANCR_TEXT_SEGMENT_BOUNDARY: /* \y */
+      r = MJ_IGNORE;
+      break;
+    default:
+      break;
+    }
+    break;
+
+  case NODE_BAG:
+    {
+      BagNode* en = BAG_(node);
+
+      if (en->type == BAG_IF_ELSE) {
+        if (IS_NOT_NULL(en->te.Then)) {
+          r = mostly_just_anychar(en->te.Then, in_reluctant);
+          if (r == MJ_YES) break;
+        }
+        if (IS_NOT_NULL(en->te.Else)) {
+          r = mostly_just_anychar(en->te.Else, in_reluctant);
+        }
+      }
+      else {
+        r = mostly_just_anychar(NODE_BODY(node), in_reluctant);
+      }
+    }
+    break;
+
+  case NODE_CTYPE:
+    if (CTYPE_(node)->ctype == CTYPE_ANYCHAR)
+      r = MJ_YES;
+    else
+      r = MJ_NO;
+    break;
+
+  case NODE_STRING:
+    if (NODE_STRING_LEN(node) == 0) {
+      r = MJ_IGNORE;
+      break;
+    }
+    /* fall */
+  case NODE_CCLASS:
+    r = MJ_NO;
+    break;
+
+#ifdef USE_CALL
+  case NODE_CALL:
+    /* ignore call */
+#endif
+  case NODE_BACKREF:
+  case NODE_GIMMICK:
+    r = MJ_IGNORE;
+    break;
+
+  default:
+    break;
+  }
+
+  return r;
+}
+
+#define MAX_CALLS_IN_DETECT   10
+
 typedef struct {
   int prec_read;
   int look_behind;
+  int backref;
   int backref_with_level;
   int call;
+  int anychar_reluctant_many;
+  int empty_check_nest_level;
+  int max_empty_check_nest_level;
+  int heavy_element;
 } SlowElementCount;
 
 static int
-node_detect_can_be_slow(Node* node, SlowElementCount* ct)
+detect_can_be_slow(Node* node, SlowElementCount* ct, int ncall, int calls[])
 {
   int r;
 
@@ -7720,13 +7978,45 @@ node_detect_can_be_slow(Node* node, SlowElementCount* ct)
   case NODE_LIST:
   case NODE_ALT:
     do {
-      r = node_detect_can_be_slow(NODE_CAR(node), ct);
+      r = detect_can_be_slow(NODE_CAR(node), ct, ncall, calls);
       if (r != 0) return r;
     } while (IS_NOT_NULL(node = NODE_CDR(node)));
     break;
 
   case NODE_QUANT:
-    r = node_detect_can_be_slow(NODE_BODY(node), ct);
+    {
+      int prev_heavy_element;
+      QuantNode* qn;
+      Node* body;
+
+      qn = QUANT_(node);
+      body = NODE_BODY(node);
+
+      if (qn->emptiness != BODY_IS_NOT_EMPTY) {
+        prev_heavy_element = ct->heavy_element;
+        ct->empty_check_nest_level++;
+        if (ct->empty_check_nest_level > ct->max_empty_check_nest_level)
+          ct->max_empty_check_nest_level = ct->empty_check_nest_level;
+      }
+      else if (IS_INFINITE_REPEAT(qn->upper) ||
+               qn->upper > MANY_REPEAT_OF_ANYCHAR) {
+        MJ_RESULT mr = mostly_just_anychar(body, (qn->greedy == 0));
+        if (mr == MJ_YES)
+          ct->anychar_reluctant_many++;
+      }
+
+      r = detect_can_be_slow(body, ct, ncall, calls);
+
+      if (qn->emptiness != BODY_IS_NOT_EMPTY) {
+        if (NODE_IS_INPEEK(node)) {
+          if (ct->empty_check_nest_level > 2) {
+            if (prev_heavy_element == ct->heavy_element)
+              ct->heavy_element++;
+          }
+        }
+        ct->empty_check_nest_level--;
+      }
+    }
     break;
 
   case NODE_ANCHOR:
@@ -7744,23 +8034,23 @@ node_detect_can_be_slow(Node* node, SlowElementCount* ct)
     }
 
     if (ANCHOR_HAS_BODY(ANCHOR_(node)))
-      r = node_detect_can_be_slow(NODE_BODY(node), ct);
+      r = detect_can_be_slow(NODE_BODY(node), ct, ncall, calls);
     break;
 
   case NODE_BAG:
     {
       BagNode* en = BAG_(node);
 
-      r = node_detect_can_be_slow(NODE_BODY(node), ct);
+      r = detect_can_be_slow(NODE_BODY(node), ct, ncall, calls);
       if (r != 0) return r;
 
       if (en->type == BAG_IF_ELSE) {
         if (IS_NOT_NULL(en->te.Then)) {
-          r = node_detect_can_be_slow(en->te.Then, ct);
+          r = detect_can_be_slow(en->te.Then, ct, ncall, calls);
           if (r != 0) return r;
         }
         if (IS_NOT_NULL(en->te.Else)) {
-          r = node_detect_can_be_slow(en->te.Else, ct);
+          r = detect_can_be_slow(en->te.Else, ct, ncall, calls);
           if (r != 0) return r;
         }
       }
@@ -7771,12 +8061,44 @@ node_detect_can_be_slow(Node* node, SlowElementCount* ct)
   case NODE_BACKREF:
     if (NODE_IS_NEST_LEVEL(node))
       ct->backref_with_level++;
+    else
+      ct->backref++;
     break;
 #endif
 
 #ifdef USE_CALL
   case NODE_CALL:
-    ct->call++;
+    {
+      int i;
+      int found;
+      int gnum;
+
+      gnum = CALL_(node)->called_gnum;
+      ct->call++;
+
+      if (NODE_IS_RECURSION(node) && NODE_IS_INPEEK(node) &&
+          NODE_IS_IN_REAL_REPEAT(node)) {
+         ct->heavy_element += 10;
+      }
+
+      found = FALSE;
+      for (i = 0; i < ncall; i++) {
+        if (gnum == calls[i]) {
+          found = TRUE;
+          break;
+        }
+      }
+
+      if (! found) {
+        if (ncall + 1 < MAX_CALLS_IN_DETECT) {
+          calls[ncall] = gnum;
+          r = detect_can_be_slow(NODE_BODY(node), ct, ncall + 1, calls);
+        }
+        else {
+          ct->heavy_element++;
+        }
+      }
+    }
     break;
 #endif
 
@@ -7795,8 +8117,12 @@ onig_detect_can_be_slow_pattern(const UChar* pattern,
   int r;
   regex_t* reg;
   Node* root;
-  ScanEnv scan_env;
+  ParseEnv scan_env;
   SlowElementCount count;
+  int calls[MAX_CALLS_IN_DETECT];
+#ifdef USE_CALL
+  UnsetAddrList  uslist = {0};
+#endif
 
   reg = (regex_t* )xmalloc(sizeof(regex_t));
   if (IS_NULL(reg)) return ONIGERR_MEMORY;
@@ -7807,25 +8133,44 @@ onig_detect_can_be_slow_pattern(const UChar* pattern,
     return r;
   }
 
-  root = 0;
-  r = onig_parse_tree(&root, pattern, pattern_end, reg, &scan_env);
+  r = parse_and_tune(reg, pattern, pattern_end, &scan_env, &root, NULL
+#ifdef USE_CALL
+                     , &uslist
+#endif
+                    );
+  if (r != 0) goto err;
+
+#ifdef USE_CALL
+  if (scan_env.num_call > 0) {
+    unset_addr_list_end(&uslist);
+  }
+#endif
+
+  count.prec_read          = 0;
+  count.look_behind        = 0;
+  count.backref            = 0;
+  count.backref_with_level = 0;
+  count.call               = 0;
+  count.anychar_reluctant_many     = 0;
+  count.empty_check_nest_level     = 0;
+  count.max_empty_check_nest_level = 0;
+  count.heavy_element = 0;
+
+  r = detect_can_be_slow(root, &count, 0, calls);
   if (r == 0) {
-    count.prec_read          = 0;
-    count.look_behind        = 0;
-    count.backref_with_level = 0;
-    count.call               = 0;
-
-    r = node_detect_can_be_slow(root, &count);
-    if (r == 0) {
-      int n = count.prec_read + count.look_behind
-            + count.backref_with_level + count.call;
-      r = n;
-    }
+    int n = count.prec_read + count.look_behind
+          + count.backref + count.backref_with_level + count.call
+          + count.anychar_reluctant_many;
+    if (count.heavy_element != 0)
+      n += count.heavy_element * 10;
+
+    r = n;
   }
 
   if (IS_NOT_NULL(scan_env.mem_env_dynamic))
     xfree(scan_env.mem_env_dynamic);
 
+ err:
   onig_node_free(root);
   onig_free(reg);
   return r;
@@ -7853,6 +8198,8 @@ Indent(FILE* f, int indent)
 static void
 print_indent_tree(FILE* f, Node* node, int indent)
 {
+  static char* emptiness_name[] = { "", " empty", " empty_mem", " empty_rec" };
+
   int i;
   NodeType type;
   UChar* p;
@@ -8019,69 +8366,83 @@ print_indent_tree(FILE* f, Node* node, int indent)
       fprintf(f, "<call:%p>", node);
       fprintf(f, " num: %d, name", cn->called_gnum);
       p_string(f, cn->name_end - cn->name, cn->name);
+      if (NODE_IS_RECURSION(node)) fprintf(f, ", recursion");
+      if (NODE_IS_INPEEK(node))    fprintf(f, ", in-peek");
+      if (NODE_IS_IN_REAL_REPEAT(node)) fprintf(f, ", in-real-repeat");
     }
     break;
 #endif
 
   case NODE_QUANT:
-    fprintf(f, "<quantifier:%p>{%d,%d}%s%s\n", node,
-            QUANT_(node)->lower, QUANT_(node)->upper,
-            (QUANT_(node)->greedy ? "" : "?"),
-            QUANT_(node)->include_referred == 0 ? "" : " referred");
-    print_indent_tree(f, NODE_BODY(node), indent + add);
+    {
+      fprintf(f, "<quantifier:%p>{%d,%d}%s%s%s", node,
+              QUANT_(node)->lower, QUANT_(node)->upper,
+              (QUANT_(node)->greedy ? "" : "?"),
+              QUANT_(node)->include_referred == 0 ? "" : " referred",
+              emptiness_name[QUANT_(node)->emptiness]);
+      if (NODE_IS_INPEEK(node)) fprintf(f, ", in-peek");
+      fprintf(f, "\n");
+      print_indent_tree(f, NODE_BODY(node), indent + add);
+    }
     break;
 
   case NODE_BAG:
-    fprintf(f, "<bag:%p> ", node);
-    if (BAG_(node)->type == BAG_IF_ELSE) {
-      Node* Then;
-      Node* Else;
-      BagNode* bn;
-
-      bn = BAG_(node);
-      fprintf(f, "if-else\n");
-      print_indent_tree(f, NODE_BODY(node), indent + add);
+    {
+      BagNode* bn = BAG_(node);
+      fprintf(f, "<bag:%p> ", node);
+      if (bn->type == BAG_IF_ELSE) {
+        Node* Then;
+        Node* Else;
+
+        fprintf(f, "if-else\n");
+        print_indent_tree(f, NODE_BODY(node), indent + add);
+
+        Then = bn->te.Then;
+        Else = bn->te.Else;
+        if (IS_NULL(Then)) {
+          Indent(f, indent + add);
+          fprintf(f, "THEN empty\n");
+        }
+        else
+          print_indent_tree(f, Then, indent + add);
 
-      Then = bn->te.Then;
-      Else = bn->te.Else;
-      if (IS_NULL(Then)) {
-        Indent(f, indent + add);
-        fprintf(f, "THEN empty\n");
+        if (IS_NULL(Else)) {
+          Indent(f, indent + add);
+          fprintf(f, "ELSE empty\n");
+        }
+        else
+          print_indent_tree(f, Else, indent + add);
       }
-      else
-        print_indent_tree(f, Then, indent + add);
+      else {
+        switch (bn->type) {
+        case BAG_OPTION:
+          fprintf(f, "option:%d", bn->o.options);
+          break;
+        case BAG_MEMORY:
+          fprintf(f, "memory:%d", bn->m.regnum);
+          if (NODE_IS_CALLED(node)) {
+            fprintf(f, ", called");
+            if (NODE_IS_RECURSION(node))
+              fprintf(f, ", recursion");
+          }
+          else if (NODE_IS_REFERENCED(node))
+            fprintf(f, ", referenced");
 
-      if (IS_NULL(Else)) {
-        Indent(f, indent + add);
-        fprintf(f, "ELSE empty\n");
+          if (NODE_IS_FIXED_ADDR(node))
+            fprintf(f, ", fixed-addr");
+          if ((bn->m.called_state & IN_PEEK) != 0)
+            fprintf(f, ", in-peek");
+          break;
+        case BAG_STOP_BACKTRACK:
+          fprintf(f, "stop-bt");
+          break;
+        default:
+          break;
+        }
+        fprintf(f, "\n");
+        print_indent_tree(f, NODE_BODY(node), indent + add);
       }
-      else
-        print_indent_tree(f, Else, indent + add);
-
-      break;
     }
-
-    switch (BAG_(node)->type) {
-    case BAG_OPTION:
-      fprintf(f, "option:%d", BAG_(node)->o.options);
-      break;
-    case BAG_MEMORY:
-      fprintf(f, "memory:%d", BAG_(node)->m.regnum);
-      if (NODE_IS_CALLED(node))
-        fprintf(f, ", called");
-      else if (NODE_IS_REFERENCED(node))
-        fprintf(f, ", referenced");
-      if (NODE_IS_FIXED_ADDR(node))
-        fprintf(f, ", fixed-addr");
-      break;
-    case BAG_STOP_BACKTRACK:
-      fprintf(f, "stop-bt");
-      break;
-    default:
-      break;
-    }
-    fprintf(f, "\n");
-    print_indent_tree(f, NODE_BODY(node), indent + add);
     break;
 
   case NODE_GIMMICK:
diff --git a/src/regenc.c b/src/regenc.c
index 27e4549..84afd1e 100644
--- a/src/regenc.c
+++ b/src/regenc.c
@@ -2,7 +2,7 @@
   regenc.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -569,6 +569,9 @@ onigenc_apply_all_case_fold_with_map(int map_size,
   r = onigenc_ascii_apply_all_case_fold(flag, f, arg);
   if (r != 0) return r;
 
+  if (CASE_FOLD_IS_ASCII_ONLY(flag))
+    return 0;
+
   for (i = 0; i < map_size; i++) {
     code = map[i].to;
     r = (*f)(map[i].from, &code, 1, arg);
@@ -588,7 +591,7 @@ onigenc_apply_all_case_fold_with_map(int map_size,
 extern int
 onigenc_get_case_fold_codes_by_str_with_map(int map_size,
     const OnigPairCaseFoldCodes map[],
-    int ess_tsett_flag, OnigCaseFoldType flag ARG_UNUSED,
+    int ess_tsett_flag, OnigCaseFoldType flag,
     const OnigUChar* p, const OnigUChar* end, OnigCaseFoldCodeItem items[])
 {
   int i, j, n;
@@ -596,7 +599,8 @@ onigenc_get_case_fold_codes_by_str_with_map(int map_size,
 
   if (0x41 <= *p && *p <= 0x5a) { /* A - Z */
     if (*p == LARGE_S && ess_tsett_flag != 0 && end > p + 1
-        && (*(p+1) == LARGE_S || *(p+1) == SMALL_S)) { /* SS */
+        && (*(p+1) == LARGE_S || *(p+1) == SMALL_S) /* SS */
+        && CASE_FOLD_IS_NOT_ASCII_ONLY(flag)) {
     ss_combination:
       items[0].byte_len = 2;
       items[0].code_len = 1;
@@ -625,7 +629,8 @@ onigenc_get_case_fold_codes_by_str_with_map(int map_size,
   }
   else if (0x61 <= *p && *p <= 0x7a) { /* a - z */
     if (*p == SMALL_S && ess_tsett_flag != 0 && end > p + 1
-        && (*(p+1) == SMALL_S || *(p+1) == LARGE_S)) {
+        && (*(p+1) == SMALL_S || *(p+1) == LARGE_S)
+        && CASE_FOLD_IS_NOT_ASCII_ONLY(flag)) {
       goto ss_combination;
     }
 
@@ -634,7 +639,8 @@ onigenc_get_case_fold_codes_by_str_with_map(int map_size,
     items[0].code[0] = (OnigCodePoint )(*p - 0x20);
     return 1;
   }
-  else if (*p == 0xdf && ess_tsett_flag != 0) {
+  else if (*p == 0xdf && ess_tsett_flag != 0
+           && CASE_FOLD_IS_NOT_ASCII_ONLY(flag)) {
     items[0].byte_len = 1;
     items[0].code_len = 2;
     items[0].code[0] = (OnigCodePoint )'s';
@@ -660,6 +666,9 @@ onigenc_get_case_fold_codes_by_str_with_map(int map_size,
   else {
     int i;
 
+    if (CASE_FOLD_IS_ASCII_ONLY(flag))
+      return 0;
+
     for (i = 0; i < map_size; i++) {
       if (*p == map[i].from) {
         items[0].byte_len = 1;
diff --git a/src/regenc.h b/src/regenc.h
index d183b97..d0b447d 100644
--- a/src/regenc.h
+++ b/src/regenc.h
@@ -142,6 +142,10 @@ struct PropertyNameCtype {
 #define ENC_GET_SKIP_OFFSET(enc) \
   (((enc)->flag & ENC_FLAG_SKIP_OFFSET_MASK)>>2)
 
+#define CASE_FOLD_IS_ASCII_ONLY(flag) \
+  (((flag) & ONIGENC_CASE_FOLD_ASCII_ONLY) != 0)
+#define CASE_FOLD_IS_NOT_ASCII_ONLY(flag) \
+  (((flag) & ONIGENC_CASE_FOLD_ASCII_ONLY) == 0)
 
 /* for encoding system implementation (internal) */
 extern int onigenc_end(void);
@@ -202,12 +206,12 @@ extern int onigenc_wb_is_break_position P_((OnigEncoding enc, UChar* p, UChar* p
 #define FOLDS1_UNFOLDS_NUM(i)  (OnigUnicodeFolds1[(i)+1])
 #define FOLDS2_UNFOLDS_NUM(i)  (OnigUnicodeFolds2[(i)+2])
 #define FOLDS3_UNFOLDS_NUM(i)  (OnigUnicodeFolds3[(i)+3])
-#define FOLDS1_UNFOLDS(i)      (OnigUnicodeFolds1 + (i) + 2)
-#define FOLDS2_UNFOLDS(i)      (OnigUnicodeFolds2 + (i) + 3)
-#define FOLDS3_UNFOLDS(i)      (OnigUnicodeFolds3 + (i) + 4)
-#define FOLDS1_NEXT_INDEX(i)   ((i) + 2 + OnigUnicodeFolds1[(i)+1])
-#define FOLDS2_NEXT_INDEX(i)   ((i) + 3 + OnigUnicodeFolds2[(i)+2])
-#define FOLDS3_NEXT_INDEX(i)   ((i) + 4 + OnigUnicodeFolds3[(i)+3])
+#define FOLDS1_UNFOLDS(i)      (FOLDS1_FOLD(i) + 2)
+#define FOLDS2_UNFOLDS(i)      (FOLDS2_FOLD(i) + 3)
+#define FOLDS3_UNFOLDS(i)      (FOLDS3_FOLD(i) + 4)
+#define FOLDS1_NEXT_INDEX(i)   ((i) + 2 + FOLDS1_UNFOLDS_NUM(i))
+#define FOLDS2_NEXT_INDEX(i)   ((i) + 3 + FOLDS2_UNFOLDS_NUM(i))
+#define FOLDS3_NEXT_INDEX(i)   ((i) + 4 + FOLDS3_UNFOLDS_NUM(i))
 
 #define FOLDS_FOLD_ADDR_BUK(buk, addr) do {\
   if ((buk)->fold_len == 1)\
diff --git a/src/regerror.c b/src/regerror.c
index dc1c8b6..18a5bdd 100644
--- a/src/regerror.c
+++ b/src/regerror.c
@@ -2,7 +2,7 @@
   regerror.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2020  K.Kosako
+ * Copyright (c) 2002-2021  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -146,6 +146,8 @@ onig_error_code_to_format(int code)
     p = "too big wide-char value"; break;
   case ONIGERR_TOO_LONG_WIDE_CHAR_VALUE:
     p = "too long wide-char value"; break;
+  case ONIGERR_UNDEFINED_OPERATOR:
+    p = "undefined operator"; break;
   case ONIGERR_INVALID_CODE_POINT_VALUE:
     p = "invalid code point value"; break;
   case ONIGERR_EMPTY_GROUP_NAME:
@@ -190,6 +192,8 @@ onig_error_code_to_format(int code)
     p = "not supported encoding combination"; break;
   case ONIGERR_INVALID_COMBINATION_OF_OPTIONS:
     p = "invalid combination of options"; break;
+  case ONIGERR_VERY_INEFFICIENT_PATTERN:
+    p = "very inefficient pattern"; break;
   case ONIGERR_LIBRARY_IS_NOT_INITIALIZED:
     p = "library is not initialized"; break;
 
diff --git a/src/regexec.c b/src/regexec.c
index bb6b474..a3cf60a 100644
--- a/src/regexec.c
+++ b/src/regexec.c
@@ -2,7 +2,7 @@
   regexec.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2020  K.Kosako
+ * Copyright (c) 2002-2021  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -54,6 +54,13 @@
   (MEM_STATUS_AT((reg)->push_mem_end, (idx)) != 0 ? \
    STACK_AT(mem_end_stk[idx].i)->u.mem.pstr : mem_end_stk[idx].s)
 
+#ifdef _MSC_VER
+#define DIST_CAST(d)   (size_t )(d)
+#else
+#define DIST_CAST(d)   (d)
+#endif
+
+
 static int forward_search(regex_t* reg, const UChar* str, const UChar* end, UChar* start, UChar* range, UChar** low, UChar** high);
 
 static int
@@ -76,11 +83,12 @@ struct OnigMatchParamStruct {
   unsigned long   retry_limit_in_match;
   unsigned long   retry_limit_in_search;
 #endif
+
+  void*           callout_user_data; /* used in callback each match */
 #ifdef USE_CALLOUT
   OnigCalloutFunc progress_callout_of_contents;
   OnigCalloutFunc retraction_callout_of_contents;
   int             match_at_call_counter;
-  void*           callout_user_data;
   CalloutData*    callout_data;
   int             callout_data_alloc_num;
 #endif
@@ -143,12 +151,8 @@ onig_set_retraction_callout_of_match_param(OnigMatchParam* param, OnigCalloutFun
 extern int
 onig_set_callout_user_data_of_match_param(OnigMatchParam* param, void* user_data)
 {
-#ifdef USE_CALLOUT
   param->callout_user_data = user_data;
   return ONIG_NORMAL;
-#else
-  return ONIG_NO_SUPPORT_CONFIG;
-#endif
 }
 
 
@@ -873,6 +877,23 @@ onig_get_capture_tree(OnigRegion* region)
 }
 #endif /* USE_CAPTURE_HISTORY */
 
+
+static OnigCallbackEachMatchFunc CallbackEachMatch;
+
+extern OnigCallbackEachMatchFunc
+onig_get_callback_each_match(void)
+{
+  return CallbackEachMatch;
+}
+
+extern int
+onig_set_callback_each_match(OnigCallbackEachMatchFunc f)
+{
+  CallbackEachMatch = f;
+  return ONIG_NORMAL;
+}
+
+
 extern void
 onig_region_clear(OnigRegion* region)
 {
@@ -1238,7 +1259,7 @@ struct OnigCalloutArgsStruct {
 #ifdef USE_FIND_LONGEST_SEARCH_ALL_OF_RANGE
 #define MATCH_ARG_INIT(msa, reg, arg_option, arg_region, arg_start, mpv) do { \
   (msa).stack_p  = (void* )0;\
-  (msa).options  = (arg_option);\
+  (msa).options  = (arg_option)|(reg)->options;\
   (msa).region   = (arg_region);\
   (msa).start    = (arg_start);\
   (msa).match_stack_limit  = (mpv)->match_stack_limit;\
@@ -1251,7 +1272,7 @@ struct OnigCalloutArgsStruct {
 #else
 #define MATCH_ARG_INIT(msa, reg, arg_option, arg_region, arg_start, mpv) do { \
   (msa).stack_p  = (void* )0;\
-  (msa).options  = (arg_option);\
+  (msa).options  = (arg_option)|(reg)->options;\
   (msa).region   = (arg_region);\
   (msa).start    = (arg_start);\
   (msa).match_stack_limit  = (mpv)->match_stack_limit;\
@@ -1405,6 +1426,7 @@ onig_set_subexp_call_limit_in_search(unsigned long n)
 
 #endif
 
+
 #ifdef USE_CALLOUT
 static OnigCalloutFunc DefaultProgressCallout;
 static OnigCalloutFunc DefaultRetractionCallout;
@@ -1452,11 +1474,12 @@ onig_initialize_match_param(OnigMatchParam* mp)
   mp->retry_limit_in_search = RetryLimitInSearch;
 #endif
 
+  mp->callout_user_data = 0;
+
 #ifdef USE_CALLOUT
   mp->progress_callout_of_contents   = DefaultProgressCallout;
   mp->retraction_callout_of_contents = DefaultRetractionCallout;
   mp->match_at_call_counter  = 0;
-  mp->callout_user_data      = 0;
   mp->callout_data           = 0;
   mp->callout_data_alloc_num = 0;
 #endif
@@ -1532,13 +1555,26 @@ onig_get_callout_data_dont_clear_old(regex_t* reg, OnigMatchParam* mp,
   t = d->slot[slot].type;
   if (IS_NOT_NULL(type)) *type = t;
   if (IS_NOT_NULL(val))  *val  = d->slot[slot].val;
-  return (t == ONIG_TYPE_VOID ? 1 : ONIG_NORMAL);
+  return (t == ONIG_TYPE_VOID ? ONIG_VALUE_IS_NOT_SET : ONIG_NORMAL);
+}
+
+extern int
+onig_get_callout_data_by_tag_dont_clear_old(regex_t* reg,
+  OnigMatchParam* mp, const UChar* tag, const UChar* tag_end, int slot,
+  OnigType* type, OnigValue* val)
+{
+  int num;
+
+  num = onig_get_callout_num_by_tag(reg, tag, tag_end);
+  if (num < 0)  return num;
+  if (num == 0) return ONIGERR_INVALID_CALLOUT_TAG_NAME;
+
+  return onig_get_callout_data_dont_clear_old(reg, mp, num, slot, type, val);
 }
 
 extern int
-onig_get_callout_data_by_callout_args_self_dont_clear_old(OnigCalloutArgs* args,
-                                                          int slot, OnigType* type,
-                                                          OnigValue* val)
+onig_get_callout_data_by_callout_args_self_dont_clear_old(
+  OnigCalloutArgs* args, int slot, OnigType* type, OnigValue* val)
 {
   return onig_get_callout_data_dont_clear_old(args->regex, args->msa->mp,
                                               args->num, slot, type, val);
@@ -1563,7 +1599,7 @@ onig_get_callout_data(regex_t* reg, OnigMatchParam* mp,
   t = d->slot[slot].type;
   if (IS_NOT_NULL(type)) *type = t;
   if (IS_NOT_NULL(val))  *val  = d->slot[slot].val;
-  return (t == ONIG_TYPE_VOID ? 1 : ONIG_NORMAL);
+  return (t == ONIG_TYPE_VOID ? ONIG_VALUE_IS_NOT_SET : ONIG_NORMAL);
 }
 
 extern int
@@ -2171,65 +2207,90 @@ stack_double(int* is_alloca, char** arg_alloc_base,
   }\
 } while (0)
 
-#ifdef USE_STUBBORN_CHECK_CAPTURES_IN_EMPTY_REPEAT
-#define STACK_EMPTY_CHECK_MEM(isnull, sid, s, reg) do {\
-  StackType* k;\
-  GET_EMPTY_CHECK_START(sid, k);\
-  if (k->u.empty_check.pstr != (s)) {\
+#ifdef USE_RIGID_CHECK_CAPTURES_IN_EMPTY_REPEAT
+#define STACK_EMPTY_CHECK_MEM(isnull, sid, empty_status_mem, s, reg) do {\
+  StackType* klow;\
+  GET_EMPTY_CHECK_START(sid, klow);\
+  if (klow->u.empty_check.pstr != (s)) {\
+  stack_empty_check_mem_not_empty:\
     (isnull) = 0;\
   }\
   else {\
-    UChar* endp;\
+    StackType *k, *kk;\
+    MemStatusType ms = (empty_status_mem);\
     (isnull) = 1;\
-    while (k < stk) {\
-      if (k->type == STK_MEM_START &&\
-        MEM_STATUS_LIMIT_AT((reg)->empty_status_mem, k->zid)) {\
-        STACK_MEM_START_GET_PREV_END_ADDR(k, reg, endp);\
-        if (endp == 0) {\
-          (isnull) = 0; break;\
-        }\
-        else if (STACK_AT(k->u.mem.prev_start.i)->u.mem.pstr != endp) {\
-          (isnull) = 0; break;\
-        }\
-        else if (endp != s) {\
-          (isnull) = -1; /* empty, but position changed */ \
+    k = stk;\
+    while (k > klow) {\
+      k--;\
+      if (k->type == STK_MEM_END && MEM_STATUS_LIMIT_AT(ms, k->zid)) {\
+        kk = klow;\
+        while (kk < k) {\
+          if (kk->type == STK_MEM_START && kk->zid == k->zid) {\
+            if (kk->u.mem.prev_end.i == INVALID_STACK_INDEX || \
+                ((STACK_AT(kk->u.mem.prev_end.i)->u.mem.pstr != k->u.mem.pstr || STACK_AT(kk->u.mem.prev_start.i)->u.mem.pstr != STACK_AT(k->u.mem.prev_start.i)->u.mem.pstr) && (STACK_AT(k->u.mem.prev_start.i)->u.mem.pstr != k->u.mem.pstr || STACK_AT(kk->u.mem.prev_start.i)->u.mem.pstr != STACK_AT(kk->u.mem.prev_end.i)->u.mem.pstr))) {\
+              goto stack_empty_check_mem_not_empty;\
+            }\
+            else {\
+              ms &= ~((MemStatusType )1 << k->zid);\
+              break;\
+            }\
+          }\
+          kk++;\
         }\
+        if (ms == 0) break;\
       }\
-      k++;\
     }\
   }\
 } while(0)
 
-#define STACK_EMPTY_CHECK_MEM_REC(isnull,sid,s,reg) do {\
+#define STACK_EMPTY_CHECK_MEM_REC(isnull,sid,empty_status_mem,s,reg) do {\
   int level = 0;\
-  StackType* k = stk;\
+  StackType* klow = stk;\
   while (1) {\
-    k--;\
-    STACK_BASE_CHECK(k, "STACK_EMPTY_CHECK_MEM_REC");\
-    if (k->type == STK_EMPTY_CHECK_START) {\
-      if (k->zid == (sid)) {\
+    klow--;\
+    STACK_BASE_CHECK(klow, "STACK_EMPTY_CHECK_MEM_REC");\
+    if (klow->type == STK_EMPTY_CHECK_START) {\
+      if (klow->zid == (sid)) {\
         if (level == 0) {\
-          if (k->u.empty_check.pstr != (s)) {\
+          if (klow->u.empty_check.pstr != (s)) {\
+          stack_empty_check_mem_rec_not_empty:\
             (isnull) = 0;\
             break;\
           }\
           else {\
-            UChar* endp;\
+            StackType *k, *kk;\
+            MemStatusType ms;\
             (isnull) = 1;\
-            while (k < stk) {\
-              if (k->type == STK_MEM_START) {\
-                if (level == 0 && \
-                  MEM_STATUS_LIMIT_AT((reg)->empty_status_mem, k->zid) !=0) {\
-                  STACK_MEM_START_GET_PREV_END_ADDR(k, reg, endp);\
-                  if (endp == 0) {\
-                    (isnull) = 0; break;\
-                  }\
-                  else if (STACK_AT(k->u.mem.prev_start.i)->u.mem.pstr != endp) { \
-                    (isnull) = 0; break;\
-                  }\
-                  else if (endp != s) {\
-                    (isnull) = -1; /* empty, but position changed */\
+            if ((empty_status_mem) == 0) break;\
+            ms = (empty_status_mem);\
+            k = stk;\
+            while (k > klow) {\
+              k--;\
+              if (k->type == STK_MEM_END) {\
+                if (level == 0 && MEM_STATUS_LIMIT_AT(ms, k->zid)) {\
+                  kk = klow;\
+                  kk++;\
+                  while (kk < k) {\
+                    if (kk->type == STK_MEM_START && kk->zid == k->zid) {\
+                      if (kk->u.mem.prev_end.i == INVALID_STACK_INDEX || \
+                          ((STACK_AT(kk->u.mem.prev_end.i)->u.mem.pstr != k->u.mem.pstr || STACK_AT(kk->u.mem.prev_start.i)->u.mem.pstr != STACK_AT(k->u.mem.prev_start.i)->u.mem.pstr) && (STACK_AT(k->u.mem.prev_start.i)->u.mem.pstr != k->u.mem.pstr || STACK_AT(kk->u.mem.prev_start.i)->u.mem.pstr != STACK_AT(kk->u.mem.prev_end.i)->u.mem.pstr))) {\
+                        goto stack_empty_check_mem_rec_not_empty;\
+                      }\
+                      else {\
+                        ms &= ~((MemStatusType )1 << k->zid);\
+                        break;\
+                      }\
+                    }\
+                    else if (kk->type == STK_EMPTY_CHECK_START) {\
+                      if (kk->zid == (sid)) level++;\
+                    }\
+                    else if (kk->type == STK_EMPTY_CHECK_END) {\
+                      if (kk->zid == (sid)) level--;\
+                    }\
+                    kk++;\
                   }\
+                  level = 0;\
+                  if (ms == 0) break;\
                 }\
               }\
               else if (k->type == STK_EMPTY_CHECK_START) {\
@@ -2238,7 +2299,6 @@ stack_double(int* is_alloca, char** arg_alloc_base,
               else if (k->type == STK_EMPTY_CHECK_END) {\
                 if (k->zid == (sid)) level--;\
               }\
-              k++;\
             }\
             break;\
           }\
@@ -2248,8 +2308,8 @@ stack_double(int* is_alloca, char** arg_alloc_base,
         }\
       }\
     }\
-    else if (k->type == STK_EMPTY_CHECK_END) {\
-      if (k->zid == (sid)) level++;\
+    else if (klow->type == STK_EMPTY_CHECK_END) {\
+      if (klow->zid == (sid)) level++;\
     }\
   }\
 } while(0)
@@ -2274,7 +2334,7 @@ stack_double(int* is_alloca, char** arg_alloc_base,
     }\
   }\
 } while(0)
-#endif /* USE_STUBBORN_CHECK_CAPTURES_IN_EMPTY_REPEAT */
+#endif /* USE_RIGID_CHECK_CAPTURES_IN_EMPTY_REPEAT */
 
 #define STACK_GET_REPEAT_COUNT_SEARCH(sid, c) do {\
   StackType* k = stk;\
@@ -2888,6 +2948,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
   StackType *stkp; /* used as any purpose. */
   StkPtrType *mem_start_stk, *mem_end_stk;
   UChar* keep;
+  OnigRegion* region;
 
 #ifdef USE_REPEAT_AND_EMPTY_CHECK_LOCAL_VAR
   StackIndex *repeat_stk;
@@ -2905,8 +2966,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
   unsigned long subexp_call_counters[MAX_SUBEXP_CALL_COUNTERS];
 #endif
 
+  OnigOptionType options;
   Operation* p = reg->ops;
-  OnigOptionType option = reg->options;
   OnigEncoding encode = reg->enc;
   OnigCaseFoldType case_fold_flag = reg->case_fold_flag;
 
@@ -2936,6 +2997,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
   }
 #endif
 
+  options = msa->options;
+
 #ifdef USE_CALLOUT
   msa->mp->match_at_call_counter++;
 #endif
@@ -2976,102 +3039,113 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
   BYTECODE_INTERPRETER_START {
     CASE_OP(END)
       n = (int )(s - sstart);
+      if (n == 0 && OPTON_FIND_NOT_EMPTY(options)) {
+        best_len = ONIG_MISMATCH;
+        goto fail; /* for retry */
+      }
+
       if (n > best_len) {
-        OnigRegion* region;
 #ifdef USE_FIND_LONGEST_SEARCH_ALL_OF_RANGE
-        if (OPTON_FIND_LONGEST(option)) {
+        if (OPTON_FIND_LONGEST(options)) {
           if (n > msa->best_len) {
             msa->best_len = n;
             msa->best_s   = (UChar* )sstart;
-            goto set_region;
           }
-          else
-            goto end_best_len;
+          else {
+            if (s >= in_right_range && msa->best_s == sstart) {
+              best_len = msa->best_len; /* end of find */
+            }
+            else {
+              SOP_OUT;
+              goto fail; /* for retry */
+            }
+          }
         }
-#endif
+        else {
+          best_len = n;
+        }
+#else
         best_len = n;
+#endif
+      }
 
-      set_region:
-        region = msa->region;
-        if (region) {
-          if (keep > s) keep = s;
+      /* set region */
+      region = msa->region;
+      if (region) {
+        if (keep > s) keep = s;
 
 #ifdef USE_POSIX_API
-          if (OPTON_POSIX_REGION(msa->options)) {
-            posix_regmatch_t* rmt = (posix_regmatch_t* )region;
-
-            rmt[0].rm_so = (regoff_t )(keep - str);
-            rmt[0].rm_eo = (regoff_t )(s    - str);
-            for (i = 1; i <= num_mem; i++) {
-              if (mem_end_stk[i].i != INVALID_STACK_INDEX) {
-                rmt[i].rm_so = (regoff_t )(STACK_MEM_START(reg, i) - str);
-                rmt[i].rm_eo = (regoff_t )(STACK_MEM_END(reg, i)   - str);
-              }
-              else {
-                rmt[i].rm_so = rmt[i].rm_eo = ONIG_REGION_NOTPOS;
-              }
+        if (OPTON_POSIX_REGION(options)) {
+          posix_regmatch_t* rmt = (posix_regmatch_t* )region;
+
+          rmt[0].rm_so = (regoff_t )(keep - str);
+          rmt[0].rm_eo = (regoff_t )(s    - str);
+          for (i = 1; i <= num_mem; i++) {
+            if (mem_end_stk[i].i != INVALID_STACK_INDEX) {
+              rmt[i].rm_so = (regoff_t )(STACK_MEM_START(reg, i) - str);
+              rmt[i].rm_eo = (regoff_t )(STACK_MEM_END(reg, i)   - str);
+            }
+            else {
+              rmt[i].rm_so = rmt[i].rm_eo = ONIG_REGION_NOTPOS;
             }
           }
-          else {
+        }
+        else {
 #endif /* USE_POSIX_API */
-            region->beg[0] = (int )(keep - str);
-            region->end[0] = (int )(s    - str);
-            for (i = 1; i <= num_mem; i++) {
-              if (mem_end_stk[i].i != INVALID_STACK_INDEX) {
-                region->beg[i] = (int )(STACK_MEM_START(reg, i) - str);
-                region->end[i] = (int )(STACK_MEM_END(reg, i)   - str);
-              }
-              else {
-                region->beg[i] = region->end[i] = ONIG_REGION_NOTPOS;
-              }
+          region->beg[0] = (int )(keep - str);
+          region->end[0] = (int )(s    - str);
+          for (i = 1; i <= num_mem; i++) {
+            if (mem_end_stk[i].i != INVALID_STACK_INDEX) {
+              region->beg[i] = (int )(STACK_MEM_START(reg, i) - str);
+              region->end[i] = (int )(STACK_MEM_END(reg, i)   - str);
+            }
+            else {
+              region->beg[i] = region->end[i] = ONIG_REGION_NOTPOS;
             }
+          }
 
 #ifdef USE_CAPTURE_HISTORY
-            if (reg->capture_history != 0) {
-              int r;
-              OnigCaptureTreeNode* node;
+          if (reg->capture_history != 0) {
+            OnigCaptureTreeNode* node;
 
-              if (IS_NULL(region->history_root)) {
-                region->history_root = node = history_node_new();
-                CHECK_NULL_RETURN_MEMERR(node);
-              }
-              else {
-                node = region->history_root;
-                history_tree_clear(node);
-              }
+            if (IS_NULL(region->history_root)) {
+              region->history_root = node = history_node_new();
+              CHECK_NULL_RETURN_MEMERR(node);
+            }
+            else {
+              node = region->history_root;
+              history_tree_clear(node);
+            }
 
-              node->group = 0;
-              node->beg   = (int )(keep - str);
-              node->end   = (int )(s    - str);
+            node->group = 0;
+            node->beg   = (int )(keep - str);
+            node->end   = (int )(s    - str);
 
-              stkp = stk_base;
-              r = make_capture_history_tree(region->history_root, &stkp,
-                                            stk, (UChar* )str, reg);
-              if (r < 0) MATCH_AT_ERROR_RETURN(r);
-            }
+            stkp = stk_base;
+            i = make_capture_history_tree(region->history_root, &stkp,
+                                          stk, (UChar* )str, reg);
+            if (i < 0) MATCH_AT_ERROR_RETURN(i);
+          }
 #endif /* USE_CAPTURE_HISTORY */
 #ifdef USE_POSIX_API
-          } /* else OPTON_POSIX_REGION() */
+        } /* else OPTON_POSIX_REGION() */
 #endif
-        } /* if (region) */
-      } /* n > best_len */
+      } /* if (region) */
 
-#ifdef USE_FIND_LONGEST_SEARCH_ALL_OF_RANGE
-    end_best_len:
-#endif
       SOP_OUT;
 
-      if (OPTON_FIND_CONDITION(option)) {
-        if (OPTON_FIND_NOT_EMPTY(option) && s == sstart) {
+      if (OPTON_CALLBACK_EACH_MATCH(options) &&
+          IS_NOT_NULL(CallbackEachMatch)) {
+        i = CallbackEachMatch(str, end, sstart, region,
+                              msa->mp->callout_user_data);
+        if (i < 0) MATCH_AT_ERROR_RETURN(i);
+
+#ifdef USE_FIND_LONGEST_SEARCH_ALL_OF_RANGE
+        if (! OPTON_FIND_LONGEST(options))
+#endif
           best_len = ONIG_MISMATCH;
-          goto fail; /* for retry */
-        }
-        if (OPTON_FIND_LONGEST(option)) {
-          if (s >= in_right_range && msa->best_s == sstart)
-            best_len = msa->best_len;
-          else
-            goto fail; /* for retry */
-        }
+
+        goto fail;
       }
 
       /* default behavior: return first-matching result. */
@@ -3564,23 +3638,23 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
     CASE_OP(BEGIN_BUF)
       if (! ON_STR_BEGIN(s)) goto fail;
-      if (OPTON_NOTBOL(msa->options)) goto fail;
-      if (OPTON_NOT_BEGIN_STRING(msa->options)) goto fail;
+      if (OPTON_NOTBOL(options)) goto fail;
+      if (OPTON_NOT_BEGIN_STRING(options)) goto fail;
 
       INC_OP;
       JUMP_OUT;
 
     CASE_OP(END_BUF)
       if (! ON_STR_END(s)) goto fail;
-      if (OPTON_NOTEOL(msa->options)) goto fail;
-      if (OPTON_NOT_END_STRING(msa->options)) goto fail;
+      if (OPTON_NOTEOL(options)) goto fail;
+      if (OPTON_NOT_END_STRING(options)) goto fail;
 
       INC_OP;
       JUMP_OUT;
 
     CASE_OP(BEGIN_LINE)
       if (ON_STR_BEGIN(s)) {
-        if (OPTON_NOTBOL(msa->options)) goto fail;
+        if (OPTON_NOTBOL(options)) goto fail;
         INC_OP;
         JUMP_OUT;
       }
@@ -3599,7 +3673,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         UChar* sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
         if (IS_EMPTY_STR || !ONIGENC_IS_MBC_NEWLINE(encode, sprev, end)) {
 #endif
-          if (OPTON_NOTEOL(msa->options)) goto fail;
+          if (OPTON_NOTEOL(options)) goto fail;
           INC_OP;
           JUMP_OUT;
 #ifndef USE_NEWLINE_AT_END_OF_STRING_HAS_EMPTY_LINE
@@ -3624,8 +3698,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         UChar* sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
         if (IS_EMPTY_STR || !ONIGENC_IS_MBC_NEWLINE(encode, sprev, end)) {
 #endif
-          if (OPTON_NOTEOL(msa->options)) goto fail;
-          if (OPTON_NOT_END_STRING(msa->options)) goto fail;
+          if (OPTON_NOTEOL(options)) goto fail;
+          if (OPTON_NOT_END_STRING(options)) goto fail;
           INC_OP;
           JUMP_OUT;
 #ifndef USE_NEWLINE_AT_END_OF_STRING_HAS_EMPTY_LINE
@@ -3634,8 +3708,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       }
       else if (ONIGENC_IS_MBC_NEWLINE(encode, s, end) &&
                ON_STR_END(s + enclen(encode, s))) {
-        if (OPTON_NOTEOL(msa->options)) goto fail;
-        if (OPTON_NOT_END_STRING(msa->options)) goto fail;
+        if (OPTON_NOTEOL(options)) goto fail;
+        if (OPTON_NOT_END_STRING(options)) goto fail;
         INC_OP;
         JUMP_OUT;
       }
@@ -3644,8 +3718,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         UChar* ss = s + enclen(encode, s);
         ss += enclen(encode, ss);
         if (ON_STR_END(ss)) {
-          if (OPTON_NOTEOL(msa->options)) goto fail;
-          if (OPTON_NOT_END_STRING(msa->options)) goto fail;
+          if (OPTON_NOTEOL(options)) goto fail;
+          if (OPTON_NOT_END_STRING(options)) goto fail;
           INC_OP;
           JUMP_OUT;
         }
@@ -3657,7 +3731,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       switch (p->check_position.type) {
       case CHECK_POSITION_SEARCH_START:
         if (s != msa->start) goto fail;
-        if (OPTON_NOT_BEGIN_POSITION(msa->options)) goto fail;
+        if (OPTON_NOT_BEGIN_POSITION(options)) goto fail;
         break;
       case CHECK_POSITION_CURRENT_RIGHT_RANGE:
         if (s != right_range) goto fail;
@@ -3924,13 +3998,13 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       }
       JUMP_OUT;
 
-#ifdef USE_STUBBORN_CHECK_CAPTURES_IN_EMPTY_REPEAT
+#ifdef USE_RIGID_CHECK_CAPTURES_IN_EMPTY_REPEAT
     CASE_OP(EMPTY_CHECK_END_MEMST)
       {
         int is_empty;
 
         mem = p->empty_check_end.mem;  /* mem: null check id */
-        STACK_EMPTY_CHECK_MEM(is_empty, mem, s, reg);
+        STACK_EMPTY_CHECK_MEM(is_empty, mem, p->empty_check_end.empty_status_mem, s, reg);
         INC_OP;
         if (is_empty) {
 #ifdef ONIG_DEBUG_MATCH
@@ -3949,8 +4023,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         int is_empty;
 
         mem = p->empty_check_end.mem;  /* mem: null check id */
-#ifdef USE_STUBBORN_CHECK_CAPTURES_IN_EMPTY_REPEAT
-        STACK_EMPTY_CHECK_MEM_REC(is_empty, mem, s, reg);
+#ifdef USE_RIGID_CHECK_CAPTURES_IN_EMPTY_REPEAT
+        STACK_EMPTY_CHECK_MEM_REC(is_empty, mem, p->empty_check_end.empty_status_mem, s, reg);
 #else
         STACK_EMPTY_CHECK_REC(is_empty, mem, s);
 #endif
@@ -4109,6 +4183,9 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         }
       }
 
+#ifdef ONIG_DEBUG_CALL
+      fprintf(DBGFP, "CALL: id:%d, at:%ld, level:%lu\n", p->call.called_mem, s - str, subexp_call_nest_counter);
+#endif
       addr = p->call.addr;
       INC_OP; STACK_PUSH_CALL_FRAME(p);
       p = reg->ops + addr;
@@ -4425,7 +4502,7 @@ regset_search_body_position_lead(OnigRegSet* set,
     sr[i].state = SRS_DEAD;
     if (reg->optimize != OPTIMIZE_NONE) {
       if (reg->dist_max != INFINITE_LEN) {
-        if (end - range > reg->dist_max)
+        if (DIST_CAST(end - range) > reg->dist_max)
           sch_range = (UChar* )range + reg->dist_max;
         else
           sch_range = (UChar* )end;
@@ -4609,7 +4686,7 @@ onig_regset_search_with_param(OnigRegSet* set,
   if (set->n == 0)
     return ONIG_MISMATCH;
 
-  if (OPTON_POSIX_REGION(option))
+  if (OPTON_POSIX_REGION(option) || OPTON_CALLBACK_EACH_MATCH(option))
     return ONIGERR_INVALID_ARGUMENT;
 
   r = 0;
@@ -4884,7 +4961,7 @@ sunday_quick_search_step_forward(regex_t* reg,
                                  const UChar* text_range)
 {
   const UChar *s, *se, *t, *p, *end;
-  const UChar *tail;
+  const UChar *tail, *next;
   int skip, tlen1;
   int map_offset;
   OnigEncoding enc;
@@ -4921,9 +4998,11 @@ sunday_quick_search_step_forward(regex_t* reg,
       s += enclen(enc, s);
     } while ((s - t) < skip && s < end);
 #else
-    s += skip;
-    if (s < end)
-      s = onigenc_get_right_adjust_char_head(enc, text, s);
+    next = s + skip;
+    if (next < end)
+      s = onigenc_get_right_adjust_char_head(enc, s, next);
+    else
+      break;
 #endif
   }
 
@@ -5086,7 +5165,7 @@ forward_search(regex_t* reg, const UChar* str, const UChar* end, UChar* start,
 
   p = start;
   if (reg->dist_min != 0) {
-    if (end - p <= reg->dist_min)
+    if (DIST_CAST(end - p) <= reg->dist_min)
       return 0; /* fail */
 
     if (ONIGENC_IS_SINGLEBYTE(reg->enc)) {
@@ -5119,7 +5198,7 @@ forward_search(regex_t* reg, const UChar* str, const UChar* end, UChar* start,
   }
 
   if (p && p < range) {
-    if (p - start < reg->dist_min) {
+    if (DIST_CAST(p - start) < reg->dist_min) {
     retry_gate:
       pprev = p;
       p += enclen(reg->enc, p);
@@ -5164,7 +5243,7 @@ forward_search(regex_t* reg, const UChar* str, const UChar* end, UChar* start,
     }
     else {
       if (reg->dist_max != INFINITE_LEN) {
-        if (p - str < reg->dist_max) {
+        if (DIST_CAST(p - str) < reg->dist_max) {
           *low = (UChar* )str;
         }
         else {
@@ -5175,7 +5254,7 @@ forward_search(regex_t* reg, const UChar* str, const UChar* end, UChar* start,
         }
       }
       /* no needs to adjust *high, *high is used as range check only */
-      if (p - str < reg->dist_min)
+      if (DIST_CAST(p - str) < reg->dist_min)
         *high = (UChar* )str;
       else
         *high = p - reg->dist_min;
@@ -5260,13 +5339,13 @@ backward_search(regex_t* reg, const UChar* str, const UChar* end, UChar* s,
     }
 
     if (reg->dist_max != INFINITE_LEN) {
-      if (p - str < reg->dist_max)
+      if (DIST_CAST(p - str) < reg->dist_max)
         *low = (UChar* )str;
       else
         *low = p - reg->dist_max;
 
       if (reg->dist_min != 0) {
-        if (p - str < reg->dist_min)
+        if (DIST_CAST(p - str) < reg->dist_min)
           *high = (UChar* )str;
         else
           *high = p - reg->dist_min;
@@ -5410,13 +5489,13 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
 
       if (range > start) {
         if (reg->anc_dist_max != INFINITE_LEN &&
-            min_semi_end - start > reg->anc_dist_max) {
+            DIST_CAST(min_semi_end - start) > reg->anc_dist_max) {
           start = min_semi_end - reg->anc_dist_max;
           if (start < end)
             start = onigenc_get_right_adjust_char_head(reg->enc, str, start);
         }
-        if (max_semi_end - (range - 1) < reg->anc_dist_min) {
-          if (max_semi_end - str + 1 < reg->anc_dist_min)
+        if (DIST_CAST(max_semi_end - (range - 1)) < reg->anc_dist_min) {
+          if (DIST_CAST(max_semi_end - str + 1) < reg->anc_dist_min)
             goto mismatch_no_msa;
           else
             range = max_semi_end - reg->anc_dist_min + 1;
@@ -5428,11 +5507,11 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
       }
       else {
         if (reg->anc_dist_max != INFINITE_LEN &&
-            min_semi_end - range > reg->anc_dist_max) {
+            DIST_CAST(min_semi_end - range) > reg->anc_dist_max) {
           range = min_semi_end - reg->anc_dist_max;
         }
-        if (max_semi_end - start < reg->anc_dist_min) {
-          if (max_semi_end - str < reg->anc_dist_min)
+        if (DIST_CAST(max_semi_end - start) < reg->anc_dist_min) {
+          if (DIST_CAST(max_semi_end - str) < reg->anc_dist_min)
             goto mismatch_no_msa;
           else {
             start = max_semi_end - reg->anc_dist_min;
@@ -5503,7 +5582,7 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
         if (reg->dist_max == INFINITE_LEN)
           sch_range = (UChar* )end;
         else {
-          if ((end - range) < reg->dist_max)
+          if (DIST_CAST(end - range) < reg->dist_max)
             sch_range = (UChar* )end;
           else {
             sch_range = (UChar* )range + reg->dist_max;
@@ -5579,14 +5658,14 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
       else
         adjrange = (UChar* )end;
 
-      if (end - range > reg->dist_min)
+      if (DIST_CAST(end - range) > reg->dist_min)
         min_range = range + reg->dist_min;
       else
         min_range = end;
 
       if (reg->dist_max != INFINITE_LEN) {
         do {
-          if (end - s > reg->dist_max)
+          if (DIST_CAST(end - s) > reg->dist_max)
             sch_start = s + reg->dist_max;
           else {
             sch_start = onigenc_get_prev_char_head(reg->enc, str, end);
@@ -5887,8 +5966,10 @@ onig_regset_add(OnigRegSet* set, regex_t* reg)
 {
   OnigRegion* region;
 
+#ifdef USE_FIND_LONGEST_SEARCH_ALL_OF_RANGE
   if (OPTON_FIND_LONGEST(reg->options))
     return ONIGERR_INVALID_ARGUMENT;
+#endif
 
   if (set->n != 0 && reg->enc != set->enc)
     return ONIGERR_INVALID_ARGUMENT;
@@ -5933,8 +6014,10 @@ onig_regset_replace(OnigRegSet* set, int at, regex_t* reg)
     set->n--;
   }
   else {
+#ifdef USE_FIND_LONGEST_SEARCH_ALL_OF_RANGE
     if (OPTON_FIND_LONGEST(reg->options))
       return ONIGERR_INVALID_ARGUMENT;
+#endif
 
     if (set->n > 1 && reg->enc != set->enc)
       return ONIGERR_INVALID_ARGUMENT;
@@ -6573,7 +6656,7 @@ onig_builtin_monitor(OnigCalloutArgs* args, void* user_data)
 
     tag_len = tag_end - tag_start;
     if (tag_len >= sizeof(buf)) tag_len = sizeof(buf) - 1;
-    for (i = 0; i < tag_len; i++) buf[i] = tag_start[i];
+    for (i = 0; i < (int )tag_len; i++) buf[i] = tag_start[i];
     buf[tag_len] = '\0';
   }
 
diff --git a/src/regint.h b/src/regint.h
index 74a5c61..9856a96 100644
--- a/src/regint.h
+++ b/src/regint.h
@@ -4,7 +4,7 @@
   regint.h -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2020  K.Kosako
+ * Copyright (c) 2002-2021  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -35,6 +35,7 @@
 /* #define ONIG_DEBUG_SEARCH */
 /* #define ONIG_DEBUG_MATCH */
 /* #define ONIG_DEBUG_MATCH_COUNTER */
+/* #define ONIG_DEBUG_CALL */
 /* #define ONIG_DONT_OPTIMIZE */
 
 /* for byte-code statistical data. */
@@ -42,7 +43,8 @@
 
 #if defined(ONIG_DEBUG_PARSE) || defined(ONIG_DEBUG_MATCH) || \
     defined(ONIG_DEBUG_SEARCH) || defined(ONIG_DEBUG_COMPILE) || \
-    defined(ONIG_DEBUG_MATCH_COUNTER) || defined(ONIG_DEBUG_STATISTICS)
+    defined(ONIG_DEBUG_MATCH_COUNTER) || defined(ONIG_DEBUG_CALL) || \
+    defined(ONIG_DEBUG_STATISTICS)
 #ifndef ONIG_DEBUG
 #define ONIG_DEBUG
 #define DBGFP   stderr
@@ -61,7 +63,7 @@
 #define USE_CALL
 #define USE_CALLOUT
 #define USE_BACKREF_WITH_LEVEL        /* \k<name+n>, \k<name-n> */
-#define USE_STUBBORN_CHECK_CAPTURES_IN_EMPTY_REPEAT     /* /(?:()|())*\2/ */
+#define USE_RIGID_CHECK_CAPTURES_IN_EMPTY_REPEAT        /* /(?:()|())*\2/ */
 #define USE_NEWLINE_AT_END_OF_STRING_HAS_EMPTY_LINE     /* /\n$/ =~ "\n" */
 #define USE_WARNING_REDUNDANT_NESTED_REPEAT_OPERATOR
 #define USE_RETRY_LIMIT
@@ -388,10 +390,10 @@ typedef unsigned int  MemStatusType;
   (IS_CODE_DIGIT_ASCII(enc,code) ? DIGITVAL(code) \
    : (ONIGENC_IS_CODE_UPPER(enc,code) ? (code) - 'A' + 10 : (code) - 'a' + 10))
 
+#define OPTON_CALLBACK_EACH_MATCH(option) \
+        ((option) & ONIG_OPTION_CALLBACK_EACH_MATCH)
 #define OPTON_FIND_LONGEST(option)   ((option) & ONIG_OPTION_FIND_LONGEST)
 #define OPTON_FIND_NOT_EMPTY(option) ((option) & ONIG_OPTION_FIND_NOT_EMPTY)
-#define OPTON_FIND_CONDITION(option) ((option) & \
-          (ONIG_OPTION_FIND_LONGEST | ONIG_OPTION_FIND_NOT_EMPTY))
 #define OPTON_NEGATE_SINGLELINE(option) ((option) & \
                                           ONIG_OPTION_NEGATE_SINGLELINE)
 #define OPTON_DONT_CAPTURE_GROUP(option) ((option) & \
@@ -406,8 +408,6 @@ typedef unsigned int  MemStatusType;
 #define OPTON_NOT_END_STRING(option)      ((option) & ONIG_OPTION_NOT_END_STRING)
 #define OPTON_NOT_BEGIN_POSITION(option)  ((option) & ONIG_OPTION_NOT_BEGIN_POSITION)
 
-#define DISABLE_CASE_FOLD_MULTI_CHAR(case_fold_flag) \
-  ((case_fold_flag) & ~INTERNAL_ONIGENC_CASE_FOLD_MULTI_CHAR)
 
 #define INFINITE_REPEAT         -1
 #define IS_INFINITE_REPEAT(n)   ((n) == INFINITE_REPEAT)
@@ -437,81 +437,6 @@ typedef Bits*     BitSetRef;
 #define BITSET_CLEAR_BIT(bs, pos)   BS_ROOM(bs,pos) &= ~(BS_BIT(pos))
 #define BITSET_INVERT_BIT(bs, pos)  BS_ROOM(bs,pos) ^= BS_BIT(pos)
 
-/* bytes buffer */
-typedef struct _BBuf {
-  UChar* p;
-  unsigned int used;
-  unsigned int alloc;
-} BBuf;
-
-#define BB_INIT(buf,size)    bbuf_init((BBuf* )(buf), (size))
-
-#define BB_EXPAND(buf,low) do{\
-  do { (buf)->alloc *= 2; } while ((buf)->alloc < (unsigned int )low);\
-  (buf)->p = (UChar* )xrealloc((buf)->p, (buf)->alloc);\
-  if (IS_NULL((buf)->p)) return(ONIGERR_MEMORY);\
-} while (0)
-
-#define BB_ENSURE_SIZE(buf,size) do{\
-  unsigned int new_alloc = (buf)->alloc;\
-  while (new_alloc < (unsigned int )(size)) { new_alloc *= 2; }\
-  if ((buf)->alloc != new_alloc) {\
-    (buf)->p = (UChar* )xrealloc((buf)->p, new_alloc);\
-    if (IS_NULL((buf)->p)) return(ONIGERR_MEMORY);\
-    (buf)->alloc = new_alloc;\
-  }\
-} while (0)
-
-#define BB_WRITE(buf,pos,bytes,n) do{\
-  int used = (pos) + (n);\
-  if ((buf)->alloc < (unsigned int )used) BB_EXPAND((buf),used);\
-  xmemcpy((buf)->p + (pos), (bytes), (n));\
-  if ((buf)->used < (unsigned int )used) (buf)->used = used;\
-} while (0)
-
-#define BB_WRITE1(buf,pos,byte) do{\
-  int used = (pos) + 1;\
-  if ((buf)->alloc < (unsigned int )used) BB_EXPAND((buf),used);\
-  (buf)->p[(pos)] = (byte);\
-  if ((buf)->used < (unsigned int )used) (buf)->used = used;\
-} while (0)
-
-#define BB_ADD(buf,bytes,n)       BB_WRITE((buf),(buf)->used,(bytes),(n))
-#define BB_ADD1(buf,byte)         BB_WRITE1((buf),(buf)->used,(byte))
-#define BB_GET_ADD_ADDRESS(buf)   ((buf)->p + (buf)->used)
-#define BB_GET_OFFSET_POS(buf)    ((buf)->used)
-
-/* from < to */
-#define BB_MOVE_RIGHT(buf,from,to,n) do {\
-  if ((unsigned int )((to)+(n)) > (buf)->alloc) BB_EXPAND((buf),(to) + (n));\
-  xmemmove((buf)->p + (to), (buf)->p + (from), (n));\
-  if ((unsigned int )((to)+(n)) > (buf)->used) (buf)->used = (to) + (n);\
-} while (0)
-
-/* from > to */
-#define BB_MOVE_LEFT(buf,from,to,n) do {\
-  xmemmove((buf)->p + (to), (buf)->p + (from), (n));\
-} while (0)
-
-/* from > to */
-#define BB_MOVE_LEFT_REDUCE(buf,from,to) do {\
-  xmemmove((buf)->p + (to), (buf)->p + (from), (buf)->used - (from));\
-  (buf)->used -= (from - to);\
-} while (0)
-
-#define BB_INSERT(buf,pos,bytes,n) do {\
-  if (pos >= (buf)->used) {\
-    BB_WRITE(buf,pos,bytes,n);\
-  }\
-  else {\
-    BB_MOVE_RIGHT((buf),(pos),(pos) + (n),((buf)->used - (pos)));\
-    xmemcpy((buf)->p + (pos), (bytes), (n));\
-  }\
-} while (0)
-
-#define BB_GET_BYTE(buf, pos) (buf)->p[(pos)]
-
-
 /* has body */
 #define ANCR_PREC_READ        (1<<0)
 #define ANCR_PREC_READ_NOT    (1<<1)
@@ -884,6 +809,7 @@ typedef struct {
     } empty_check_start;
     struct {
       MemNumType mem;
+      MemStatusType empty_status_mem;
     } empty_check_end; /* EMPTY_CHECK_END, EMPTY_CHECK_END_MEMST, EMPTY_CHECK_END_MEMST_PUSH */
     struct {
       RelAddrType addr;
@@ -922,7 +848,7 @@ typedef struct {
     } update_var;
     struct {
       AbsAddrType addr;
-#ifdef ONIG_DEBUG_MATCH_COUNTER
+#if defined(ONIG_DEBUG_MATCH_COUNTER) || defined(ONIG_DEBUG_CALL)
       MemNumType called_mem;
 #endif
     } call;
@@ -977,7 +903,6 @@ struct re_pattern_buffer {
   MemStatusType  capture_history;  /* (?@...) flag (1-31) */
   MemStatusType  push_mem_start;   /* need backtrack flag */
   MemStatusType  push_mem_end;     /* need backtrack flag */
-  MemStatusType  empty_status_mem;
   int            stack_pop_level;
   int            repeat_range_alloc;
   RepeatRange*   repeat_range;
diff --git a/src/regparse.c b/src/regparse.c
index dd2824b..938a569 100644
--- a/src/regparse.c
+++ b/src/regparse.c
@@ -2,7 +2,7 @@
   regparse.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2020  K.Kosako
+ * Copyright (c) 2002-2021  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -159,6 +159,75 @@ OnigSyntaxType OnigSyntaxRuby = {
 
 OnigSyntaxType*  OnigDefaultSyntax = ONIG_SYNTAX_ONIGURUMA;
 
+
+#define BB_INIT(buf,size)    bbuf_init((BBuf* )(buf), (size))
+
+#define BB_EXPAND(buf,low) do{\
+  do { (buf)->alloc *= 2; } while ((buf)->alloc < (unsigned int )low);\
+  (buf)->p = (UChar* )xrealloc((buf)->p, (buf)->alloc);\
+  if (IS_NULL((buf)->p)) return(ONIGERR_MEMORY);\
+} while (0)
+
+#define BB_ENSURE_SIZE(buf,size) do{\
+  unsigned int new_alloc = (buf)->alloc;\
+  while (new_alloc < (unsigned int )(size)) { new_alloc *= 2; }\
+  if ((buf)->alloc != new_alloc) {\
+    (buf)->p = (UChar* )xrealloc((buf)->p, new_alloc);\
+    if (IS_NULL((buf)->p)) return(ONIGERR_MEMORY);\
+    (buf)->alloc = new_alloc;\
+  }\
+} while (0)
+
+#define BB_WRITE(buf,pos,bytes,n) do{\
+  int used = (pos) + (n);\
+  if ((buf)->alloc < (unsigned int )used) BB_EXPAND((buf),used);\
+  xmemcpy((buf)->p + (pos), (bytes), (n));\
+  if ((buf)->used < (unsigned int )used) (buf)->used = used;\
+} while (0)
+
+#define BB_WRITE1(buf,pos,byte) do{\
+  int used = (pos) + 1;\
+  if ((buf)->alloc < (unsigned int )used) BB_EXPAND((buf),used);\
+  (buf)->p[(pos)] = (byte);\
+  if ((buf)->used < (unsigned int )used) (buf)->used = used;\
+} while (0)
+
+#define BB_ADD(buf,bytes,n)       BB_WRITE((buf),(buf)->used,(bytes),(n))
+#define BB_ADD1(buf,byte)         BB_WRITE1((buf),(buf)->used,(byte))
+#define BB_GET_ADD_ADDRESS(buf)   ((buf)->p + (buf)->used)
+#define BB_GET_OFFSET_POS(buf)    ((buf)->used)
+
+/* from < to */
+#define BB_MOVE_RIGHT(buf,from,to,n) do {\
+  if ((unsigned int )((to)+(n)) > (buf)->alloc) BB_EXPAND((buf),(to) + (n));\
+  xmemmove((buf)->p + (to), (buf)->p + (from), (n));\
+  if ((unsigned int )((to)+(n)) > (buf)->used) (buf)->used = (to) + (n);\
+} while (0)
+
+/* from > to */
+#define BB_MOVE_LEFT(buf,from,to,n) do {\
+  xmemmove((buf)->p + (to), (buf)->p + (from), (n));\
+} while (0)
+
+/* from > to */
+#define BB_MOVE_LEFT_REDUCE(buf,from,to) do {\
+  xmemmove((buf)->p + (to), (buf)->p + (from), (buf)->used - (from));\
+  (buf)->used -= (from - to);\
+} while (0)
+
+#define BB_INSERT(buf,pos,bytes,n) do {\
+  if (pos >= (buf)->used) {\
+    BB_WRITE(buf,pos,bytes,n);\
+  }\
+  else {\
+    BB_MOVE_RIGHT((buf),(pos),(pos) + (n),((buf)->used - (pos)));\
+    xmemcpy((buf)->p + (pos), (bytes), (n));\
+  }\
+} while (0)
+
+#define BB_GET_BYTE(buf, pos) (buf)->p[(pos)]
+
+
 typedef enum {
   CS_VALUE,
   CS_RANGE,
@@ -300,7 +369,7 @@ bbuf_clone(BBuf** rto, BBuf* from)
 }
 
 static int
-backref_rel_to_abs(int rel_no, ScanEnv* env)
+backref_rel_to_abs(int rel_no, ParseEnv* env)
 {
   if (rel_no > 0) {
     if (rel_no > ONIG_INT_MAX - env->num_mem)
@@ -981,7 +1050,7 @@ onig_number_of_names(regex_t* reg)
 #endif /* else USE_ST_LIBRARY */
 
 static int
-name_add(regex_t* reg, UChar* name, UChar* name_end, int backref, ScanEnv* env)
+name_add(regex_t* reg, UChar* name, UChar* name_end, int backref, ParseEnv* env)
 {
   int r;
   int alloc;
@@ -1115,7 +1184,7 @@ onig_name_to_group_numbers(regex_t* reg, const UChar* name,
 }
 
 static int
-name_to_group_numbers(ScanEnv* env, const UChar* name, const UChar* name_end,
+name_to_group_numbers(ParseEnv* env, const UChar* name, const UChar* name_end,
                       int** nums)
 {
   regex_t* reg;
@@ -1920,7 +1989,7 @@ callout_tag_table_new(CalloutTagTable** rt)
 }
 
 static int
-callout_tag_entry_raw(ScanEnv* env, CalloutTagTable* t, UChar* name,
+callout_tag_entry_raw(ParseEnv* env, CalloutTagTable* t, UChar* name,
                       UChar* name_end, CalloutTagVal entry_val)
 {
   int r;
@@ -1963,7 +2032,7 @@ ext_ensure_tag_table(regex_t* reg)
 }
 
 static int
-callout_tag_entry(ScanEnv* env, regex_t* reg, UChar* name, UChar* name_end,
+callout_tag_entry(ParseEnv* env, regex_t* reg, UChar* name, UChar* name_end,
                   CalloutTagVal entry_val)
 {
   int r;
@@ -1988,10 +2057,10 @@ callout_tag_entry(ScanEnv* env, regex_t* reg, UChar* name, UChar* name_end,
 #endif /* USE_CALLOUT */
 
 
-#define INIT_SCANENV_MEMENV_ALLOC_SIZE   16
+#define INIT_PARSEENV_MEMENV_ALLOC_SIZE   16
 
 static void
-scan_env_clear(ScanEnv* env)
+scan_env_clear(ParseEnv* env)
 {
   MEM_STATUS_CLEAR(env->cap_history);
   MEM_STATUS_CLEAR(env->backtrack_mem);
@@ -2024,7 +2093,7 @@ scan_env_clear(ScanEnv* env)
 }
 
 static int
-scan_env_add_mem_entry(ScanEnv* env)
+scan_env_add_mem_entry(ParseEnv* env)
 {
   int i, need, alloc;
   MemEnv* p;
@@ -2033,10 +2102,10 @@ scan_env_add_mem_entry(ScanEnv* env)
   if (need > MaxCaptureNum && MaxCaptureNum != 0)
     return ONIGERR_TOO_MANY_CAPTURES;
 
-  if (need >= SCANENV_MEMENV_SIZE) {
+  if (need >= PARSEENV_MEMENV_SIZE) {
     if (env->mem_alloc <= need) {
       if (IS_NULL(env->mem_env_dynamic)) {
-        alloc = INIT_SCANENV_MEMENV_ALLOC_SIZE;
+        alloc = INIT_PARSEENV_MEMENV_ALLOC_SIZE;
         p = (MemEnv* )xmalloc(sizeof(MemEnv) * alloc);
         CHECK_NULL_RETURN_MEMERR(p);
         xmemcpy(p, env->mem_env_static, sizeof(env->mem_env_static));
@@ -2062,10 +2131,10 @@ scan_env_add_mem_entry(ScanEnv* env)
 }
 
 static int
-scan_env_set_mem_node(ScanEnv* env, int num, Node* node)
+scan_env_set_mem_node(ParseEnv* env, int num, Node* node)
 {
   if (env->num_mem >= num)
-    SCANENV_MEMENV(env)[num].mem_node = node;
+    PARSEENV_MEMENV(env)[num].mem_node = node;
   else
     return ONIGERR_PARSER_BUG;
   return 0;
@@ -2285,7 +2354,7 @@ node_new_anychar(OnigOptionType options)
 }
 
 static int
-node_new_no_newline(Node** node, ScanEnv* env)
+node_new_no_newline(Node** node, ParseEnv* env)
 {
   Node* n;
 
@@ -2425,7 +2494,7 @@ node_new_backref(int back_num, int* backrefs, int by_name,
 #ifdef USE_BACKREF_WITH_LEVEL
                  int exist_level, int nest_level,
 #endif
-                 ScanEnv* env)
+                 ParseEnv* env)
 {
   int i;
   Node* node;
@@ -2451,7 +2520,7 @@ node_new_backref(int back_num, int* backrefs, int by_name,
 
   for (i = 0; i < back_num; i++) {
     if (backrefs[i] <= env->num_mem &&
-        IS_NULL(SCANENV_MEMENV(env)[backrefs[i]].mem_node)) {
+        IS_NULL(PARSEENV_MEMENV(env)[backrefs[i]].mem_node)) {
       NODE_STATUS_ADD(node, RECURSION);   /* /...(\1).../ */
       break;
     }
@@ -2481,7 +2550,7 @@ node_new_backref_checker(int back_num, int* backrefs, int by_name,
 #ifdef USE_BACKREF_WITH_LEVEL
                          int exist_level, int nest_level,
 #endif
-                         ScanEnv* env)
+                         ParseEnv* env)
 {
   Node* node;
 
@@ -2527,6 +2596,7 @@ node_new_quantifier(int lower, int upper, int by_number)
   QUANT_(node)->head_exact       = NULL_NODE;
   QUANT_(node)->next_head_exact  = NULL_NODE;
   QUANT_(node)->include_referred = 0;
+  QUANT_(node)->empty_status_mem = 0;
   if (by_number != 0)
     NODE_STATUS_ADD(node, BY_NUMBER);
 
@@ -2640,7 +2710,7 @@ node_set_fail(Node* node)
 }
 
 static int
-node_new_fail(Node** node, ScanEnv* env)
+node_new_fail(Node** node, ParseEnv* env)
 {
   *node = node_new();
   CHECK_NULL_RETURN_MEMERR(*node);
@@ -2656,7 +2726,7 @@ onig_node_reset_fail(Node* node)
 }
 
 static int
-node_new_save_gimmick(Node** node, enum SaveType save_type, ScanEnv* env)
+node_new_save_gimmick(Node** node, enum SaveType save_type, ParseEnv* env)
 {
   int id;
 
@@ -2675,7 +2745,7 @@ node_new_save_gimmick(Node** node, enum SaveType save_type, ScanEnv* env)
 
 static int
 node_new_update_var_gimmick(Node** node, enum UpdateVarType update_var_type,
-                            int id, ScanEnv* env)
+                            int id, ParseEnv* env)
 {
   *node = node_new();
   CHECK_NULL_RETURN_MEMERR(*node);
@@ -2689,7 +2759,7 @@ node_new_update_var_gimmick(Node** node, enum UpdateVarType update_var_type,
 }
 
 static int
-node_new_keep(Node** node, ScanEnv* env)
+node_new_keep(Node** node, ParseEnv* env)
 {
   int r;
 
@@ -2743,7 +2813,7 @@ onig_reg_callout_list_at(regex_t* reg, int num)
 }
 
 static int
-reg_callout_list_entry(ScanEnv* env, int* rnum)
+reg_callout_list_entry(ParseEnv* env, int* rnum)
 {
 #define INIT_CALLOUT_LIST_NUM  3
 
@@ -2795,7 +2865,7 @@ reg_callout_list_entry(ScanEnv* env, int* rnum)
 
 static int
 node_new_callout(Node** node, OnigCalloutOf callout_of, int num, int id,
-                 ScanEnv* env)
+                 ParseEnv* env)
 {
   *node = node_new();
   CHECK_NULL_RETURN_MEMERR(*node);
@@ -2811,7 +2881,7 @@ node_new_callout(Node** node, OnigCalloutOf callout_of, int num, int id,
 #endif
 
 static int
-make_text_segment(Node** node, ScanEnv* env)
+make_text_segment(Node** node, ParseEnv* env)
 {
   int r;
   int i;
@@ -2868,7 +2938,7 @@ make_text_segment(Node** node, ScanEnv* env)
 static int
 make_absent_engine(Node** node, int pre_save_right_id, Node* absent,
                    Node* step_one, int lower, int upper, int possessive,
-                   int is_range_cutter, ScanEnv* env)
+                   int is_range_cutter, ParseEnv* env)
 {
   int r;
   int i;
@@ -2950,7 +3020,7 @@ make_absent_engine(Node** node, int pre_save_right_id, Node* absent,
 
 static int
 make_absent_tail(Node** node1, Node** node2, int pre_save_right_id,
-                 ScanEnv* env)
+                 ParseEnv* env)
 {
   int r;
   int id;
@@ -2998,7 +3068,7 @@ make_absent_tail(Node** node1, Node** node2, int pre_save_right_id,
 }
 
 static int
-make_range_clear(Node** node, ScanEnv* env)
+make_range_clear(Node** node, ParseEnv* env)
 {
   int r;
   int id;
@@ -3057,7 +3127,7 @@ make_range_clear(Node** node, ScanEnv* env)
 
 static int
 is_simple_one_char_repeat(Node* node, Node** rquant, Node** rbody,
-                          int* is_possessive, ScanEnv* env)
+                          int* is_possessive, ParseEnv* env)
 {
   Node* quant;
   Node* body;
@@ -3123,8 +3193,8 @@ is_simple_one_char_repeat(Node* node, Node** rquant, Node** rbody,
 }
 
 static int
-make_absent_tree_for_simple_one_char_repeat(Node** node, Node* absent, Node* quant,
-                                            Node* body, int possessive, ScanEnv* env)
+make_absent_tree_for_simple_one_char_repeat(Node** node,
+  Node* absent, Node* quant, Node* body, int possessive, ParseEnv* env)
 {
   int r;
   int i;
@@ -3171,7 +3241,7 @@ make_absent_tree_for_simple_one_char_repeat(Node** node, Node* absent, Node* qua
 
 static int
 make_absent_tree(Node** node, Node* absent, Node* expr, int is_range_cutter,
-                 ScanEnv* env)
+                 ParseEnv* env)
 {
   int r;
   int i;
@@ -3844,7 +3914,7 @@ add_code_range_to_buf(BBuf** pbuf, OnigCodePoint from, OnigCodePoint to)
 }
 
 static int
-add_code_range(BBuf** pbuf, ScanEnv* env, OnigCodePoint from, OnigCodePoint to)
+add_code_range(BBuf** pbuf, ParseEnv* env, OnigCodePoint from, OnigCodePoint to)
 {
   if (from > to) {
     if (IS_SYNTAX_BV(env->syntax, ONIG_SYN_ALLOW_EMPTY_RANGE_IN_CC))
@@ -4172,7 +4242,7 @@ or_cclass(CClassNode* dest, CClassNode* cc, OnigEncoding enc)
 }
 
 static OnigCodePoint
-conv_backslash_value(OnigCodePoint c, ScanEnv* env)
+conv_backslash_value(OnigCodePoint c, ParseEnv* env)
 {
   if (IS_SYNTAX_OP(env->syntax, ONIG_SYN_OP_ESC_CONTROL_CHARS)) {
     switch (c) {
@@ -4258,10 +4328,10 @@ enum ReduceType {
   RQ_ASIS = 0, /* as is */
   RQ_DEL  = 1, /* delete parent */
   RQ_A,        /* to '*'    */
+  RQ_P,        /* to '+'    */
   RQ_AQ,       /* to '*?'   */
   RQ_QQ,       /* to '??'   */
   RQ_P_QQ,     /* to '+)??' */
-  RQ_PQ_Q      /* to '+?)?' */
 };
 
 static enum ReduceType ReduceTypeTable[6][6] = {
@@ -4270,7 +4340,7 @@ static enum ReduceType ReduceTypeTable[6][6] = {
   {RQ_A,    RQ_A,    RQ_DEL, RQ_ASIS, RQ_P_QQ, RQ_DEL},  /* '+'  */
   {RQ_DEL,  RQ_AQ,   RQ_AQ,  RQ_DEL,  RQ_AQ,   RQ_AQ},   /* '??' */
   {RQ_DEL,  RQ_DEL,  RQ_DEL, RQ_DEL,  RQ_DEL,  RQ_DEL},  /* '*?' */
-  {RQ_ASIS, RQ_PQ_Q, RQ_DEL, RQ_AQ,   RQ_AQ,   RQ_DEL}   /* '+?' */
+  {RQ_ASIS, RQ_A,    RQ_P,   RQ_AQ,   RQ_AQ,   RQ_DEL}   /* '+?' */
 };
 
 extern int
@@ -4309,6 +4379,11 @@ onig_reduce_nested_quantifier(Node* pnode)
     p->lower  = 0;  p->upper = INFINITE_REPEAT;  p->greedy = 1;
     goto remove_cnode;
     break;
+  case RQ_P:
+    NODE_BODY(pnode) = NODE_BODY(cnode);
+    p->lower  = 1;  p->upper = INFINITE_REPEAT;  p->greedy = 1;
+    goto remove_cnode;
+    break;
   case RQ_AQ:
     NODE_BODY(pnode) = NODE_BODY(cnode);
     p->lower  = 0;  p->upper = INFINITE_REPEAT;  p->greedy = 0;
@@ -4323,10 +4398,6 @@ onig_reduce_nested_quantifier(Node* pnode)
     p->lower  = 0;  p->upper = 1;  p->greedy = 0;
     c->lower  = 1;  c->upper = INFINITE_REPEAT;  c->greedy = 1;
     break;
-  case RQ_PQ_Q:
-    p->lower  = 0;  p->upper = 1;  p->greedy = 1;
-    c->lower  = 1;  c->upper = INFINITE_REPEAT;  c->greedy = 0;
-    break;
   case RQ_ASIS:
     break;
   }
@@ -4340,7 +4411,7 @@ onig_reduce_nested_quantifier(Node* pnode)
 }
 
 static int
-node_new_general_newline(Node** node, ScanEnv* env)
+node_new_general_newline(Node** node, ParseEnv* env)
 {
   int r;
   int dlen, alen;
@@ -4472,7 +4543,7 @@ ptoken_init(PToken* tok)
 }
 
 static int
-fetch_interval(UChar** src, UChar* end, PToken* tok, ScanEnv* env)
+fetch_interval(UChar** src, UChar* end, PToken* tok, ParseEnv* env)
 {
   int low, up, syn_allow, non_low = 0;
   int r = 0;
@@ -4575,7 +4646,8 @@ fetch_interval(UChar** src, UChar* end, PToken* tok, ScanEnv* env)
 
 /* \M-, \C-, \c, or \... */
 static int
-fetch_escaped_value_raw(UChar** src, UChar* end, ScanEnv* env, OnigCodePoint* val)
+fetch_escaped_value_raw(UChar** src, UChar* end, ParseEnv* env,
+                        OnigCodePoint* val)
 {
   int v;
   OnigCodePoint c;
@@ -4646,7 +4718,7 @@ fetch_escaped_value_raw(UChar** src, UChar* end, ScanEnv* env, OnigCodePoint* va
 }
 
 static int
-fetch_escaped_value(UChar** src, UChar* end, ScanEnv* env, OnigCodePoint* val)
+fetch_escaped_value(UChar** src, UChar* end, ParseEnv* env, OnigCodePoint* val)
 {
   int r;
   int len;
@@ -4660,7 +4732,7 @@ fetch_escaped_value(UChar** src, UChar* end, ScanEnv* env, OnigCodePoint* val)
   return 0;
 }
 
-static int fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env);
+static int fetch_token(PToken* tok, UChar** src, UChar* end, ParseEnv* env);
 
 static OnigCodePoint
 get_name_end_code_point(OnigCodePoint start)
@@ -4691,7 +4763,7 @@ enum REF_NUM {
 */
 static int
 fetch_name_with_level(OnigCodePoint start_code, UChar** src, UChar* end,
-                      UChar** rname_end, ScanEnv* env,
+                      UChar** rname_end, ParseEnv* env,
                       int* rback_num, int* rlevel, enum REF_NUM* num_type)
 {
   int r, sign, exist_level;
@@ -4825,7 +4897,7 @@ fetch_name_with_level(OnigCodePoint start_code, UChar** src, UChar* end,
 */
 static int
 fetch_name(OnigCodePoint start_code, UChar** src, UChar* end,
-           UChar** rname_end, ScanEnv* env, int* rback_num,
+           UChar** rname_end, ParseEnv* env, int* rback_num,
            enum REF_NUM* num_type, int is_ref)
 {
   int r, sign;
@@ -4957,7 +5029,7 @@ fetch_name(OnigCodePoint start_code, UChar** src, UChar* end,
 }
 
 static void
-CC_ESC_WARN(ScanEnv* env, UChar *c)
+CC_ESC_WARN(ParseEnv* env, UChar *c)
 {
   if (onig_warn == onig_null_warn) return ;
 
@@ -4973,7 +5045,7 @@ CC_ESC_WARN(ScanEnv* env, UChar *c)
 }
 
 static void
-CLOSE_BRACKET_WITHOUT_ESC_WARN(ScanEnv* env, UChar* c)
+CLOSE_BRACKET_WITHOUT_ESC_WARN(ParseEnv* env, UChar* c)
 {
   if (onig_warn == onig_null_warn) return ;
 
@@ -5054,11 +5126,12 @@ str_exist_check_with_esc(OnigCodePoint s[], int n, UChar* from, UChar* to,
 }
 
 static int
-fetch_token_cc(PToken* tok, UChar** src, UChar* end, ScanEnv* env, int state)
+fetch_token_cc(PToken* tok, UChar** src, UChar* end, ParseEnv* env, int state)
 {
   int r;
   OnigCodePoint code;
   OnigCodePoint c, c2;
+  int mindigits, maxdigits;
   OnigSyntaxType* syn = env->syntax;
   OnigEncoding enc = env->enc;
   UChar* prev;
@@ -5247,10 +5320,11 @@ fetch_token_cc(PToken* tok, UChar** src, UChar* end, ScanEnv* env, int state)
 
     case 'u':
       if (PEND) break;
-
       prev = p;
       if (IS_SYNTAX_OP2(syn, ONIG_SYN_OP2_ESC_U_HEX4)) {
-        r = scan_hexadecimal_number(&p, end, 4, 4, enc, &code);
+        mindigits = maxdigits = 4;
+      u_hex_digits:
+        r = scan_hexadecimal_number(&p, end, mindigits, maxdigits, enc, &code);
         if (r < 0) return r;
         if (p == prev) {  /* can't read nothing. */
           code = 0; /* but, it's not error */
@@ -5261,6 +5335,15 @@ fetch_token_cc(PToken* tok, UChar** src, UChar* end, ScanEnv* env, int state)
       }
       break;
 
+    case 'U':
+      if (PEND) break;
+      prev = p;
+      if (IS_SYNTAX_BV(syn, ONIG_SYN_PYTHON)) {
+        mindigits = maxdigits = 8;
+        goto u_hex_digits;
+      }
+      break;
+
     case '0':
     case '1': case '2': case '3': case '4': case '5': case '6': case '7':
       if (IS_SYNTAX_OP(syn, ONIG_SYN_OP_ESC_OCTAL3)) {
@@ -5327,15 +5410,22 @@ fetch_token_cc(PToken* tok, UChar** src, UChar* end, ScanEnv* env, int state)
 }
 
 static int
-fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
+fetch_token(PToken* tok, UChar** src, UChar* end, ParseEnv* env)
 {
   int r;
   OnigCodePoint code;
   OnigCodePoint c;
-  OnigEncoding enc = env->enc;
-  OnigSyntaxType* syn = env->syntax;
+  int mindigits, maxdigits;
   UChar* prev;
-  UChar* p = *src;
+  int allow_num;
+  OnigEncoding enc;
+  OnigSyntaxType* syn;
+  UChar* p;
+
+  enc = env->enc;
+  syn = env->syntax;
+  p = *src;
+
   PFETCH_READY;
 
   if (tok->code_point_continue != 0) {
@@ -5574,12 +5664,20 @@ fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
       break;
 
     case 'Z':
-      if (! IS_SYNTAX_OP(syn, ONIG_SYN_OP_ESC_AZ_BUF_ANCHOR)) break;
-      tok->type = TK_ANCHOR;
-      tok->u.subtype = ANCR_SEMI_END_BUF;
+      if (IS_SYNTAX_BV(syn, ONIG_SYN_PYTHON)) {
+        goto end_buf;
+      }
+      else {
+        if (! IS_SYNTAX_OP(syn, ONIG_SYN_OP_ESC_AZ_BUF_ANCHOR)) break;
+        tok->type = TK_ANCHOR;
+        tok->u.subtype = ANCR_SEMI_END_BUF;
+      }
       break;
 
     case 'z':
+      if (IS_SYNTAX_BV(syn, ONIG_SYN_PYTHON))
+        return ONIGERR_UNDEFINED_OPERATOR;
+
       if (! IS_SYNTAX_OP(syn, ONIG_SYN_OP_ESC_AZ_BUF_ANCHOR)) break;
     end_buf:
       tok->type = TK_ANCHOR;
@@ -5668,10 +5766,11 @@ fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
 
     case 'u':
       if (PEND) break;
-
       prev = p;
+      mindigits = maxdigits = 4;
       if (IS_SYNTAX_OP2(syn, ONIG_SYN_OP2_ESC_U_HEX4)) {
-        r = scan_hexadecimal_number(&p, end, 4, 4, enc, &code);
+    u_hex_digits:
+        r = scan_hexadecimal_number(&p, end, mindigits, maxdigits, enc, &code);
         if (r < 0) return r;
         if (p == prev) {  /* can't read nothing. */
           code = 0; /* but, it's not error */
@@ -5682,6 +5781,15 @@ fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
       }
       break;
 
+    case 'U':
+      if (PEND) break;
+      prev = p;
+      if (IS_SYNTAX_BV(syn, ONIG_SYN_PYTHON)) {
+        mindigits = maxdigits = 8;
+        goto u_hex_digits;
+      }
+      break;
+
     case '1': case '2': case '3': case '4':
     case '5': case '6': case '7': case '8': case '9':
       PUNFETCH;
@@ -5694,7 +5802,7 @@ fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
       if (IS_SYNTAX_OP(syn, ONIG_SYN_OP_DECIMAL_BACKREF) &&
           (r <= env->num_mem || r <= 9)) { /* This spec. from GNU regex */
         if (IS_SYNTAX_BV(syn, ONIG_SYN_STRICT_CHECK_BACKREF)) {
-          if (r > env->num_mem || IS_NULL(SCANENV_MEMENV(env)[r].mem_node))
+          if (r > env->num_mem || IS_NULL(PARSEENV_MEMENV(env)[r].mem_node))
             return ONIGERR_INVALID_BACKREF;
         }
 
@@ -5743,6 +5851,9 @@ fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
           int back_num;
           enum REF_NUM num_type;
 
+          allow_num = 1;
+
+        backref_start:
           prev = p;
 
 #ifdef USE_BACKREF_WITH_LEVEL
@@ -5757,6 +5868,8 @@ fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
           if (r < 0) return r;
 
           if (num_type != IS_NOT_NUM) {
+            if (allow_num == 0) return ONIGERR_INVALID_BACKREF;
+
             if (num_type == IS_REL_NUM) {
               back_num = backref_rel_to_abs(back_num, env);
             }
@@ -5765,7 +5878,7 @@ fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
 
             if (IS_SYNTAX_BV(syn, ONIG_SYN_STRICT_CHECK_BACKREF)) {
               if (back_num > env->num_mem ||
-                  IS_NULL(SCANENV_MEMENV(env)[back_num].mem_node))
+                  IS_NULL(PARSEENV_MEMENV(env)[back_num].mem_node))
                 return ONIGERR_INVALID_BACKREF;
             }
             tok->type = TK_BACKREF;
@@ -5782,7 +5895,7 @@ fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
               int i;
               for (i = 0; i < num; i++) {
                 if (backs[i] > env->num_mem ||
-                    IS_NULL(SCANENV_MEMENV(env)[backs[i]].mem_node))
+                    IS_NULL(PARSEENV_MEMENV(env)[backs[i]].mem_node))
                   return ONIGERR_INVALID_BACKREF;
               }
             }
@@ -5813,12 +5926,17 @@ fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
           UChar* name_end;
           enum REF_NUM num_type;
 
+          allow_num = 1;
+
+        call_start:
           prev = p;
           r = fetch_name((OnigCodePoint )c, &p, end, &name_end, env,
                          &gnum, &num_type, TRUE);
           if (r < 0) return r;
 
           if (num_type != IS_NOT_NUM) {
+            if (allow_num == 0) return ONIGERR_UNDEFINED_GROUP_REFERENCE;
+
             if (num_type == IS_REL_NUM) {
               gnum = backref_rel_to_abs(gnum, env);
               if (gnum < 0) {
@@ -5975,6 +6093,7 @@ fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
     case '(':
       if (!PEND && PPEEK_IS('?') &&
           IS_SYNTAX_OP2(syn, ONIG_SYN_OP2_QMARK_GROUP_EFFECT)) {
+        prev = p;
         PINC;
         if (! PEND) {
           c = PPEEK;
@@ -6062,11 +6181,35 @@ fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env)
               break;
             }
           }
+          else if (c == 'P' &&
+                   IS_SYNTAX_OP2(env->syntax, ONIG_SYN_OP2_QMARK_CAPITAL_P_NAME)) {
+            PINC; /* skip 'P' */
+            if (PEND) return ONIGERR_END_PATTERN_IN_GROUP;
+            PFETCH(c);
+            allow_num = 0;
+            if (c == '=') {
+              c = '(';
+              goto backref_start;
+            }
+            else if (c == '>') {
+#ifdef USE_CALL
+              c = '(';
+              goto call_start;
+#else
+              return ONIGERR_UNDEFINED_OPERATOR;
+#endif
+            }
+            else {
+              p = prev;
+              goto lparen_qmark_end2;
+            }
+          }
         }
       lparen_qmark_end:
         PUNFETCH;
       }
 
+    lparen_qmark_end2:
       if (! IS_SYNTAX_OP(syn, ONIG_SYN_OP_LPAREN_SUBEXP)) break;
       tok->type = TK_SUBEXP_OPEN;
       break;
@@ -6295,7 +6438,7 @@ add_ctype_to_cc_by_range_limit(CClassNode* cc, int ctype ARG_UNUSED, int not,
 }
 
 static int
-add_ctype_to_cc(CClassNode* cc, int ctype, int not, ScanEnv* env)
+add_ctype_to_cc(CClassNode* cc, int ctype, int not, ParseEnv* env)
 {
   int c, r;
   int ascii_mode;
@@ -6398,7 +6541,7 @@ add_ctype_to_cc(CClassNode* cc, int ctype, int not, ScanEnv* env)
 }
 
 static int
-prs_posix_bracket(CClassNode* cc, UChar** src, UChar* end, ScanEnv* env)
+prs_posix_bracket(CClassNode* cc, UChar** src, UChar* end, ParseEnv* env)
 {
 #define POSIX_BRACKET_CHECK_LIMIT_LENGTH  20
 #define POSIX_BRACKET_NAME_MIN_LEN         4
@@ -6472,7 +6615,7 @@ prs_posix_bracket(CClassNode* cc, UChar** src, UChar* end, ScanEnv* env)
 }
 
 static int
-fetch_char_property_to_ctype(UChar** src, UChar* end, ScanEnv* env)
+fetch_char_property_to_ctype(UChar** src, UChar* end, ParseEnv* env)
 {
   int r;
   OnigCodePoint c;
@@ -6507,7 +6650,8 @@ fetch_char_property_to_ctype(UChar** src, UChar* end, ScanEnv* env)
 }
 
 static int
-prs_char_property(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
+prs_char_property(Node** np, PToken* tok, UChar** src, UChar* end,
+                  ParseEnv* env)
 {
   int r, ctype;
   CClassNode* cc;
@@ -6528,7 +6672,7 @@ prs_char_property(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
 
 static int
 cc_cprop_next(CClassNode* cc, OnigCodePoint* pcode, CVAL* val, CSTATE* state,
-              ScanEnv* env)
+              ParseEnv* env)
 {
   int r;
 
@@ -6552,7 +6696,7 @@ cc_cprop_next(CClassNode* cc, OnigCodePoint* pcode, CVAL* val, CSTATE* state,
 static int
 cc_char_next(CClassNode* cc, OnigCodePoint *from, OnigCodePoint to,
              int* from_raw, int to_raw, CVAL intype, CVAL* type,
-             CSTATE* state, ScanEnv* env)
+             CSTATE* state, ParseEnv* env)
 {
   int r;
 
@@ -6621,7 +6765,7 @@ cc_char_next(CClassNode* cc, OnigCodePoint *from, OnigCodePoint to,
 
 static int
 code_exist_check(OnigCodePoint c, UChar* from, UChar* end, int ignore_escaped,
-                 ScanEnv* env)
+                 ParseEnv* env)
 {
   int in_esc;
   OnigCodePoint code;
@@ -6643,7 +6787,7 @@ code_exist_check(OnigCodePoint c, UChar* from, UChar* end, int ignore_escaped,
 }
 
 static int
-prs_cc(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
+prs_cc(Node** np, PToken* tok, UChar** src, UChar* end, ParseEnv* env)
 {
   int r, neg, len, fetched, and_start;
   OnigCodePoint in_code, curr_code;
@@ -6995,13 +7139,14 @@ prs_cc(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
 }
 
 static int prs_alts(Node** top, PToken* tok, int term,
-                    UChar** src, UChar* end, ScanEnv* env, int group_head);
+                    UChar** src, UChar* end, ParseEnv* env, int group_head);
 
 #ifdef USE_CALLOUT
 
 /* (?{...}[tag][+-]) (?{{...}}[tag][+-]) */
 static int
-prs_callout_of_contents(Node** np, int cterm, UChar** src, UChar* end, ScanEnv* env)
+prs_callout_of_contents(Node** np, int cterm, UChar** src, UChar* end,
+                        ParseEnv* env)
 {
   int r;
   int i;
@@ -7184,7 +7329,7 @@ clear_callout_args(int n, unsigned int types[], OnigValue vals[])
 static int
 prs_callout_args(int skip_mode, int cterm, UChar** src, UChar* end,
                  int max_arg_num, unsigned int types[], OnigValue vals[],
-                 ScanEnv* env)
+                 ParseEnv* env)
 {
 #define MAX_CALLOUT_ARG_BYTE_LENGTH   128
 
@@ -7347,7 +7492,8 @@ prs_callout_args(int skip_mode, int cterm, UChar** src, UChar* end,
 
 /* (*name[TAG]) (*name[TAG]{a,b,..}) */
 static int
-prs_callout_of_name(Node** np, int cterm, UChar** src, UChar* end, ScanEnv* env)
+prs_callout_of_name(Node** np, int cterm, UChar** src, UChar* end,
+                    ParseEnv* env)
 {
   int r;
   int i;
@@ -7514,7 +7660,7 @@ prs_callout_of_name(Node** np, int cterm, UChar** src, UChar* end, ScanEnv* env)
 
 static int
 prs_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
-        ScanEnv* env)
+        ParseEnv* env)
 {
   int r, num;
   Node *target;
@@ -7747,7 +7893,7 @@ prs_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
 
             if (IS_SYNTAX_BV(env->syntax, ONIG_SYN_STRICT_CHECK_BACKREF)) {
               if (back_num > env->num_mem ||
-                  IS_NULL(SCANENV_MEMENV(env)[back_num].mem_node))
+                  IS_NULL(PARSEENV_MEMENV(env)[back_num].mem_node))
                 return ONIGERR_INVALID_BACKREF;
             }
 
@@ -7769,7 +7915,7 @@ prs_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
               int i;
               for (i = 0; i < num; i++) {
                 if (backs[i] > env->num_mem ||
-                    IS_NULL(SCANENV_MEMENV(env)[backs[i]].mem_node))
+                    IS_NULL(PARSEENV_MEMENV(env)[backs[i]].mem_node))
                   return ONIGERR_INVALID_BACKREF;
               }
             }
@@ -7932,12 +8078,26 @@ prs_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
       break;
 #endif
 
+    case 'P':
+      if (IS_SYNTAX_OP2(env->syntax, ONIG_SYN_OP2_QMARK_CAPITAL_P_NAME)) {
+        if (PEND) return ONIGERR_END_PATTERN_IN_GROUP;
+        PFETCH(c);
+        if (c == '<') goto named_group1;
+
+        return ONIGERR_UNDEFINED_GROUP_OPTION;
+      }
+      /* else fall */
+    case 'W': case 'D': case 'S':
+    case 'y':
+      if (! IS_SYNTAX_OP2(env->syntax, ONIG_SYN_OP2_OPTION_ONIGURUMA))
+        return ONIGERR_UNDEFINED_GROUP_OPTION;
+      /* else fall */
+
 #ifdef USE_POSIXLINE_OPTION
     case 'p':
 #endif
+    case 'a':
     case '-': case 'i': case 'm': case 's': case 'x':
-    case 'W': case 'D': case 'S': case 'P':
-    case 'y':
       {
         int neg = 0;
 
@@ -7974,10 +8134,26 @@ prs_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
             OPTION_NEGATE(option, ONIG_OPTION_MULTILINE|ONIG_OPTION_SINGLELINE, neg);
             break;
 #endif
-          case 'W': OPTION_NEGATE(option, ONIG_OPTION_WORD_IS_ASCII, neg); break;
-          case 'D': OPTION_NEGATE(option, ONIG_OPTION_DIGIT_IS_ASCII, neg); break;
-          case 'S': OPTION_NEGATE(option, ONIG_OPTION_SPACE_IS_ASCII, neg); break;
-          case 'P': OPTION_NEGATE(option, ONIG_OPTION_POSIX_IS_ASCII, neg); break;
+          case 'W':
+            if (! IS_SYNTAX_OP2(env->syntax, ONIG_SYN_OP2_OPTION_ONIGURUMA))
+              return ONIGERR_UNDEFINED_GROUP_OPTION;
+            OPTION_NEGATE(option, ONIG_OPTION_WORD_IS_ASCII, neg);
+            break;
+          case 'D':
+            if (! IS_SYNTAX_OP2(env->syntax, ONIG_SYN_OP2_OPTION_ONIGURUMA))
+              return ONIGERR_UNDEFINED_GROUP_OPTION;
+            OPTION_NEGATE(option, ONIG_OPTION_DIGIT_IS_ASCII, neg);
+            break;
+          case 'S':
+            if (! IS_SYNTAX_OP2(env->syntax, ONIG_SYN_OP2_OPTION_ONIGURUMA))
+              return ONIGERR_UNDEFINED_GROUP_OPTION;
+            OPTION_NEGATE(option, ONIG_OPTION_SPACE_IS_ASCII, neg);
+            break;
+          case 'P':
+            if (! IS_SYNTAX_OP2(env->syntax, ONIG_SYN_OP2_OPTION_ONIGURUMA))
+              return ONIGERR_UNDEFINED_GROUP_OPTION;
+            OPTION_NEGATE(option, ONIG_OPTION_POSIX_IS_ASCII, neg);
+            break;
 
           case 'y': /* y{g}, y{w} */
             {
@@ -8016,8 +8192,15 @@ prs_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
               PFETCH(c);
               if (c != '}')
                 return ONIGERR_UNDEFINED_GROUP_OPTION;
-              break;
             } /* case 'y' */
+            break;
+
+          case 'a':
+            if (! IS_SYNTAX_BV(env->syntax, ONIG_SYN_PYTHON))
+              return ONIGERR_UNDEFINED_GROUP_OPTION;
+
+            OPTION_NEGATE(option, ONIG_OPTION_POSIX_IS_ASCII, neg);
+            break;
 
           default:
             return ONIGERR_UNDEFINED_GROUP_OPTION;
@@ -8112,7 +8295,7 @@ static const char* ReduceQStr[] = {
 };
 
 static int
-assign_quantifier_body(Node* qnode, Node* target, int group, ScanEnv* env)
+assign_quantifier_body(Node* qnode, Node* target, int group, ParseEnv* env)
 {
   QuantNode* qn;
 
@@ -8260,35 +8443,38 @@ onig_new_cclass_with_code_list(Node** rnode, OnigEncoding enc,
 }
 
 typedef struct {
-  ScanEnv*    env;
+  ParseEnv*   env;
   CClassNode* cc;
   Node*       alt_root;
   Node**      ptail;
 } IApplyCaseFoldArg;
 
 static int
-i_apply_case_fold(OnigCodePoint from, OnigCodePoint to[], int to_len, void* arg)
+i_apply_case_fold(OnigCodePoint from, OnigCodePoint to[], int to_len,
+                  void* arg)
 {
   IApplyCaseFoldArg* iarg;
-  ScanEnv* env;
+  ParseEnv* env;
+  OnigEncoding enc;
   CClassNode* cc;
 
   iarg = (IApplyCaseFoldArg* )arg;
   env = iarg->env;
   cc  = iarg->cc;
+  enc = env->enc;
 
   if (to_len == 1) {
-    int is_in = onig_is_code_in_cc(env->enc, from, cc);
+    int is_in = onig_is_code_in_cc(enc, from, cc);
 #ifdef CASE_FOLD_IS_APPLIED_INSIDE_NEGATIVE_CCLASS
     if ((is_in != 0 && !IS_NCCLASS_NOT(cc)) ||
         (is_in == 0 &&  IS_NCCLASS_NOT(cc))) {
-      ADD_CODE_INTO_CC(cc, *to, env->enc);
+      ADD_CODE_INTO_CC(cc, *to, enc);
     }
 #else
     if (is_in != 0) {
-      if (ONIGENC_MBC_MINLEN(env->enc) > 1 ||
-          ONIGENC_CODE_TO_MBCLEN(env->enc, *to) != 1) {
-        if (IS_NCCLASS_NOT(cc)) clear_not_flag_cclass(cc, env->enc);
+      if (ONIGENC_MBC_MINLEN(enc) > 1 ||
+          ONIGENC_CODE_TO_MBCLEN(enc, *to) != 1) {
+        if (IS_NCCLASS_NOT(cc)) clear_not_flag_cclass(cc, enc);
         add_code_range(&(cc->mbuf), env, *to, *to);
       }
       else {
@@ -8305,7 +8491,7 @@ i_apply_case_fold(OnigCodePoint from, OnigCodePoint to[], int to_len, void* arg)
     int r, i, len;
     UChar buf[ONIGENC_CODE_TO_MBC_MAXLEN];
 
-    if (onig_is_code_in_cc(env->enc, from, cc)
+    if (onig_is_code_in_cc(enc, from, cc)
 #ifdef CASE_FOLD_IS_APPLIED_INSIDE_NEGATIVE_CCLASS
         && !IS_NCCLASS_NOT(cc)
 #endif
@@ -8320,8 +8506,9 @@ i_apply_case_fold(OnigCodePoint from, OnigCodePoint to[], int to_len, void* arg)
         Node* csnode;
         CClassNode* cs_cc;
 
-        index = onigenc_unicode_fold1_key(&to[i]);
-        if (index >= 0) {
+        index = 0;
+        if (ONIGENC_IS_UNICODE_ENCODING(enc) &&
+            (index = onigenc_unicode_fold1_key(&to[i])) >= 0) {
           csnode = node_new_cclass();
           cs_cc = CCLASS_(csnode);
           if (IS_NULL(csnode)) {
@@ -8332,18 +8519,22 @@ i_apply_case_fold(OnigCodePoint from, OnigCodePoint to[], int to_len, void* arg)
           m = FOLDS1_UNFOLDS_NUM(index);
           for (j = 0; j < m; j++) {
             code = FOLDS1_UNFOLDS(index)[j];
-            ADD_CODE_INTO_CC(cs_cc, code, env->enc);
+            ADD_CODE_INTO_CC(cs_cc, code, enc);
           }
-          ADD_CODE_INTO_CC(cs_cc, to[i], env->enc);
+          ADD_CODE_INTO_CC(cs_cc, to[i], enc);
           ns[n++] = csnode;
         }
         else {
-          len = ONIGENC_CODE_TO_MBC(env->enc, to[i], buf);
+          len = ONIGENC_CODE_TO_MBC(enc, to[i], buf);
           if (n == 0 || NODE_TYPE(ns[n-1]) != NODE_STRING) {
             csnode = node_new_str(buf, buf + len);
             if (IS_NULL(csnode)) goto err_free_ns;
 
-            NODE_STRING_SET_CASE_EXPANDED(csnode);
+            if (index == 0)
+              NODE_STATUS_ADD(csnode, IGNORECASE);
+            else
+              NODE_STRING_SET_CASE_EXPANDED(csnode);
+
             ns[n++] = csnode;
           }
           else {
@@ -8372,7 +8563,7 @@ i_apply_case_fold(OnigCodePoint from, OnigCodePoint to[], int to_len, void* arg)
 
 static int
 prs_exp(Node** np, PToken* tok, int term, UChar** src, UChar* end,
-        ScanEnv* env, int group_head)
+        ParseEnv* env, int group_head)
 {
   int r, len, group;
   Node* qn;
@@ -8778,7 +8969,7 @@ prs_exp(Node** np, PToken* tok, int term, UChar** src, UChar* end,
 
 static int
 prs_branch(Node** top, PToken* tok, int term, UChar** src, UChar* end,
-           ScanEnv* env, int group_head)
+           ParseEnv* env, int group_head)
 {
   int r;
   Node *node, **headp;
@@ -8829,7 +9020,7 @@ prs_branch(Node** top, PToken* tok, int term, UChar** src, UChar* end,
 /* term_tok: TK_EOT or TK_SUBEXP_CLOSE */
 static int
 prs_alts(Node** top, PToken* tok, int term, UChar** src, UChar* end,
-         ScanEnv* env, int group_head)
+         ParseEnv* env, int group_head)
 {
   int r;
   Node *node, **headp;
@@ -8892,7 +9083,7 @@ prs_alts(Node** top, PToken* tok, int term, UChar** src, UChar* end,
 }
 
 static int
-prs_regexp(Node** top, UChar** src, UChar* end, ScanEnv* env)
+prs_regexp(Node** top, UChar** src, UChar* end, ParseEnv* env)
 {
   int r;
   PToken tok;
@@ -8908,7 +9099,7 @@ prs_regexp(Node** top, UChar** src, UChar* end, ScanEnv* env)
 
 #ifdef USE_CALL
 static int
-make_call_zero_body(Node* node, ScanEnv* env, Node** rnode)
+make_call_zero_body(Node* node, ParseEnv* env, Node** rnode)
 {
   int r;
 
@@ -8930,7 +9121,7 @@ make_call_zero_body(Node* node, ScanEnv* env, Node** rnode)
 
 extern int
 onig_parse_tree(Node** root, const UChar* pattern, const UChar* end,
-                regex_t* reg, ScanEnv* env)
+                regex_t* reg, ParseEnv* env)
 {
   int r;
   UChar* p;
@@ -8945,7 +9136,6 @@ onig_parse_tree(Node** root, const UChar* pattern, const UChar* end,
   reg->num_empty_check    = 0;
   reg->repeat_range_alloc = 0;
   reg->repeat_range       = (RepeatRange* )NULL;
-  reg->empty_status_mem   = 0;
 
   names_clear(reg);
 
@@ -8990,7 +9180,7 @@ onig_parse_tree(Node** root, const UChar* pattern, const UChar* end,
 }
 
 extern void
-onig_scan_env_set_error_string(ScanEnv* env, int ecode ARG_UNUSED,
+onig_scan_env_set_error_string(ParseEnv* env, int ecode ARG_UNUSED,
                                UChar* arg, UChar* arg_end)
 {
   env->error     = arg;
diff --git a/src/regparse.h b/src/regparse.h
index c60a42d..8875f78 100644
--- a/src/regparse.h
+++ b/src/regparse.h
@@ -4,7 +4,7 @@
   regparse.h -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2020  K.Kosako
+ * Copyright (c) 2002-2021  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -73,6 +73,14 @@ enum BodyEmptyType {
   BODY_MAY_BE_EMPTY_REC = 3
 };
 
+/* bytes buffer */
+typedef struct _BBuf {
+  UChar* p;
+  unsigned int used;
+  unsigned int alloc;
+} BBuf;
+
+
 struct _Node;
 
 typedef struct {
@@ -110,6 +118,7 @@ typedef struct {
   struct _Node* head_exact;
   struct _Node* next_head_exact;
   int include_referred;  /* include called node. don't eliminate even if {0} */
+  MemStatusType empty_status_mem;
 } QuantNode;
 
 typedef struct {
@@ -340,6 +349,7 @@ typedef struct {
 #define NODE_ST_ABSENT_WITH_SIDE_EFFECTS (1<<24)  /* stopper or clear */
 #define NODE_ST_FIXED_CLEN_MIN_SURE (1<<25)
 #define NODE_ST_REFERENCED          (1<<26)
+#define NODE_ST_INPEEK              (1<<27)
 
 
 #define NODE_STATUS(node)           (((Node* )node)->u.base.status)
@@ -376,6 +386,7 @@ typedef struct {
 #define NODE_IS_ABSENT_WITH_SIDE_EFFECTS(node)  ((NODE_STATUS(node) & NODE_ST_ABSENT_WITH_SIDE_EFFECTS) != 0)
 #define NODE_IS_FIXED_CLEN_MIN_SURE(node)  ((NODE_STATUS(node) & NODE_ST_FIXED_CLEN_MIN_SURE) != 0)
 #define NODE_IS_REFERENCED(node)      ((NODE_STATUS(node) & NODE_ST_REFERENCED) != 0)
+#define NODE_IS_INPEEK(node)          ((NODE_STATUS(node) & NODE_ST_INPEEK) != 0)
 
 #define NODE_PARENT(node)         ((node)->u.base.parent)
 #define NODE_BODY(node)           ((node)->u.base.body)
@@ -384,8 +395,8 @@ typedef struct {
 #define NODE_CALL_BODY(node)      ((node)->body)
 #define NODE_ANCHOR_BODY(node)    ((node)->body)
 
-#define SCANENV_MEMENV_SIZE  8
-#define SCANENV_MEMENV(senv) \
+#define PARSEENV_MEMENV_SIZE  8
+#define PARSEENV_MEMENV(senv) \
  (IS_NOT_NULL((senv)->mem_env_dynamic) ? \
     (senv)->mem_env_dynamic : (senv)->mem_env_static)
 
@@ -424,7 +435,7 @@ typedef struct {
   int              num_mem;
   int              num_named;
   int              mem_alloc;
-  MemEnv           mem_env_static[SCANENV_MEMENV_SIZE];
+  MemEnv           mem_env_static[PARSEENV_MEMENV_SIZE];
   MemEnv*          mem_env_dynamic;
   int              backref_num;
   int              keep_num;
@@ -439,14 +450,14 @@ typedef struct {
 #ifdef ONIG_DEBUG_PARSE
   unsigned int     max_parse_depth;
 #endif
-} ScanEnv;
+} ParseEnv;
 
 
 extern int    onig_renumber_name_table P_((regex_t* reg, GroupNumMap* map));
 
 extern int    onig_strncmp P_((const UChar* s1, const UChar* s2, int n));
 extern void   onig_strcpy P_((UChar* dest, const UChar* src, const UChar* end));
-extern void   onig_scan_env_set_error_string P_((ScanEnv* env, int ecode, UChar* arg, UChar* arg_end));
+extern void   onig_scan_env_set_error_string P_((ParseEnv* env, int ecode, UChar* arg, UChar* arg_end));
 extern int    onig_reduce_nested_quantifier P_((Node* pnode));
 extern int    onig_node_copy(Node** rcopy, Node* from);
 extern int    onig_node_str_cat P_((Node* node, const UChar* s, const UChar* end));
@@ -460,7 +471,7 @@ extern Node*  onig_node_new_str P_((const UChar* s, const UChar* end));
 extern Node*  onig_node_new_list P_((Node* left, Node* right));
 extern Node*  onig_node_new_alt P_((Node* left, Node* right));
 extern int    onig_names_free P_((regex_t* reg));
-extern int    onig_parse_tree P_((Node** root, const UChar* pattern, const UChar* end, regex_t* reg, ScanEnv* env));
+extern int    onig_parse_tree P_((Node** root, const UChar* pattern, const UChar* end, regex_t* reg, ParseEnv* env));
 extern int    onig_free_shared_cclass_table P_((void));
 extern int    onig_is_code_in_cc P_((OnigEncoding enc, OnigCodePoint code, CClassNode* cc));
 extern int    onig_new_cclass_with_code_list(Node** rnode, OnigEncoding enc, int n, OnigCodePoint codes[]);
diff --git a/src/regposix.c b/src/regposix.c
index 497ba02..494446f 100644
--- a/src/regposix.c
+++ b/src/regposix.c
@@ -2,7 +2,7 @@
   regposix.c - Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2020  K.Kosako
+ * Copyright (c) 2002-2021  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -120,6 +120,7 @@ onig2posix_error_code(int code)
     { ONIGERR_NUMBERED_BACKREF_OR_CALL_NOT_ALLOWED,       REG_BADPAT  },
     { ONIGERR_TOO_BIG_WIDE_CHAR_VALUE,                    REG_EONIG_BADWC },
     { ONIGERR_TOO_LONG_WIDE_CHAR_VALUE,                   REG_EONIG_BADWC },
+    { ONIGERR_UNDEFINED_OPERATOR,                         REG_BADPAT  },
     { ONIGERR_INVALID_CODE_POINT_VALUE,                   REG_EONIG_BADWC },
     { ONIGERR_EMPTY_GROUP_NAME,                           REG_BADPAT },
     { ONIGERR_INVALID_GROUP_NAME,                         REG_BADPAT },
@@ -141,6 +142,7 @@ onig2posix_error_code(int code)
     { ONIGERR_INVALID_CALLOUT_TAG_NAME,                   REG_BADPAT },
     { ONIGERR_INVALID_CALLOUT_ARG,                        REG_BADPAT },
     { ONIGERR_NOT_SUPPORTED_ENCODING_COMBINATION,         REG_EONIG_BADARG },
+    { ONIGERR_VERY_INEFFICIENT_PATTERN,                   REG_BADPAT },
     { ONIGERR_LIBRARY_IS_NOT_INITIALIZED,                 REG_EONIG_INTERNAL }
   };
 
diff --git a/src/regsyntax.c b/src/regsyntax.c
index 984aac6..8e1c313 100644
--- a/src/regsyntax.c
+++ b/src/regsyntax.c
@@ -2,7 +2,7 @@
   regsyntax.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2020  K.Kosako
+ * Copyright (c) 2002-2021  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -240,6 +240,35 @@ OnigSyntaxType OnigSyntaxPerl_NG = {
   }
 };
 
+/* Python 3.9 */
+OnigSyntaxType OnigSyntaxPython = {
+  (( SYN_GNU_REGEX_OP | ONIG_SYN_OP_QMARK_NON_GREEDY |
+     ONIG_SYN_OP_ESC_OCTAL3 | ONIG_SYN_OP_ESC_X_HEX2 |
+     ONIG_SYN_OP_ESC_CONTROL_CHARS |
+     ONIG_SYN_OP_ESC_C_CONTROL )
+   & ~ONIG_SYN_OP_ESC_LTGT_WORD_BEGIN_END )
+  , ( ONIG_SYN_OP2_QMARK_GROUP_EFFECT | ONIG_SYN_OP2_OPTION_PERL |
+      ONIG_SYN_OP2_QMARK_LPAREN_IF_ELSE |
+      ONIG_SYN_OP2_ASTERISK_CALLOUT_NAME    |
+      ONIG_SYN_OP2_ESC_P_BRACE_CHAR_PROPERTY  |
+      ONIG_SYN_OP2_ESC_P_BRACE_CIRCUMFLEX_NOT |
+      ONIG_SYN_OP2_QMARK_CAPITAL_P_NAME       |
+      ONIG_SYN_OP2_ESC_CAPITAL_K_KEEP |
+      ONIG_SYN_OP2_ESC_V_VTAB | ONIG_SYN_OP2_ESC_U_HEX4 )
+  , ( SYN_GNU_REGEX_BV | ONIG_SYN_ISOLATED_OPTION_CONTINUE_BRANCH |
+      ONIG_SYN_ALLOW_INTERVAL_LOW_ABBREV | ONIG_SYN_PYTHON )
+  , ONIG_OPTION_SINGLELINE
+  ,
+  {
+      (OnigCodePoint )'\\'                       /* esc */
+    , (OnigCodePoint )ONIG_INEFFECTIVE_META_CHAR /* anychar '.'  */
+    , (OnigCodePoint )ONIG_INEFFECTIVE_META_CHAR /* anytime '*'  */
+    , (OnigCodePoint )ONIG_INEFFECTIVE_META_CHAR /* zero or one time '?' */
+    , (OnigCodePoint )ONIG_INEFFECTIVE_META_CHAR /* one or more time '+' */
+    , (OnigCodePoint )ONIG_INEFFECTIVE_META_CHAR /* anychar anytime */
+  }
+};
+
 
 
 extern int
diff --git a/src/unicode.c b/src/unicode.c
index 6703d4b..efe5f73 100644
--- a/src/unicode.c
+++ b/src/unicode.c
@@ -2,7 +2,7 @@
   unicode.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -77,9 +77,8 @@ static const unsigned short EncUNICODE_ISO_8859_1_CtypeTable[256] = {
 #include "unicode_fold_data.c"
 
 extern int
-onigenc_unicode_mbc_case_fold(OnigEncoding enc,
-    OnigCaseFoldType flag ARG_UNUSED, const UChar** pp, const UChar* end,
-    UChar* fold)
+onigenc_unicode_mbc_case_fold(OnigEncoding enc, OnigCaseFoldType flag,
+    const UChar** pp, const UChar* end, UChar* fold)
 {
   const struct ByUnfoldKey* buk;
 
@@ -104,23 +103,27 @@ onigenc_unicode_mbc_case_fold(OnigEncoding enc,
   }
 #endif
 
-  buk = onigenc_unicode_unfold_key(code);
-  if (buk != 0) {
-    if (buk->fold_len == 1) {
-      return ONIGENC_CODE_TO_MBC(enc, *FOLDS1_FOLD(buk->index), fold);
-    }
-    else {
-      OnigCodePoint* addr;
-
-      FOLDS_FOLD_ADDR_BUK(buk, addr);
-      rlen = 0;
-      for (i = 0; i < buk->fold_len; i++) {
-        OnigCodePoint c = addr[i];
-        len = ONIGENC_CODE_TO_MBC(enc, c, fold);
-        fold += len;
-        rlen += len;
+  if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) || ONIGENC_IS_ASCII_CODE(code)) {
+    buk = onigenc_unicode_unfold_key(code);
+    if (buk != 0) {
+      if (buk->fold_len == 1) {
+        if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) ||
+            ONIGENC_IS_ASCII_CODE(*FOLDS1_FOLD(buk->index)))
+          return ONIGENC_CODE_TO_MBC(enc, *FOLDS1_FOLD(buk->index), fold);
+      }
+      else {
+        OnigCodePoint* addr;
+
+        FOLDS_FOLD_ADDR_BUK(buk, addr);
+        rlen = 0;
+        for (i = 0; i < buk->fold_len; i++) {
+          OnigCodePoint c = addr[i];
+          len = ONIGENC_CODE_TO_MBC(enc, c, fold);
+          fold += len;
+          rlen += len;
+        }
+        return rlen;
       }
-      return rlen;
     }
   }
 
@@ -131,16 +134,22 @@ onigenc_unicode_mbc_case_fold(OnigEncoding enc,
 }
 
 static int
-apply_case_fold1(int from, int to, OnigApplyAllCaseFoldFunc f, void* arg)
+apply_case_fold1(OnigCaseFoldType flag, int from, int to,
+                 OnigApplyAllCaseFoldFunc f, void* arg)
 {
   int i, j, k, n, r;
 
   for (i = from; i < to; ) {
     OnigCodePoint fold = *FOLDS1_FOLD(i);
+    if (CASE_FOLD_IS_ASCII_ONLY(flag) && ! ONIGENC_IS_ASCII_CODE(fold)) break;
+
     n = FOLDS1_UNFOLDS_NUM(i);
     for (j = 0; j < n; j++) {
       OnigCodePoint unfold = FOLDS1_UNFOLDS(i)[j];
 
+      if (CASE_FOLD_IS_ASCII_ONLY(flag) && ! ONIGENC_IS_ASCII_CODE(unfold))
+        continue;
+
       r = (*f)(fold, &unfold, 1, arg);
       if (r != 0) return r;
       r = (*f)(unfold, &fold, 1, arg);
@@ -148,6 +157,9 @@ apply_case_fold1(int from, int to, OnigApplyAllCaseFoldFunc f, void* arg)
 
       for (k = 0; k < j; k++) {
         OnigCodePoint unfold2 = FOLDS1_UNFOLDS(i)[k];
+        if (CASE_FOLD_IS_ASCII_ONLY(flag) &&
+            ! ONIGENC_IS_ASCII_CODE(unfold2)) continue;
+
         r = (*f)(unfold, &unfold2, 1, arg);
         if (r != 0) return r;
         r = (*f)(unfold2, &unfold, 1, arg);
@@ -225,7 +237,7 @@ onigenc_unicode_apply_all_case_fold(OnigCaseFoldType flag,
 {
   int r;
 
-  r = apply_case_fold1(0, FOLDS1_NORMAL_END_INDEX, f, arg);
+  r = apply_case_fold1(flag, 0, FOLDS1_NORMAL_END_INDEX, f, arg);
   if (r != 0) return r;
 
 #ifdef USE_UNICODE_CASE_FOLD_TURKISH_AZERI
@@ -246,7 +258,7 @@ onigenc_unicode_apply_all_case_fold(OnigCaseFoldType flag,
   }
   else {
 #endif
-    r = apply_case_fold1(FOLDS1_NORMAL_END_INDEX, FOLDS1_END_INDEX, f, arg);
+    r = apply_case_fold1(flag, FOLDS1_NORMAL_END_INDEX, FOLDS1_END_INDEX, f, arg);
     if (r != 0) return r;
 #ifdef USE_UNICODE_CASE_FOLD_TURKISH_AZERI
   }
@@ -288,6 +300,9 @@ onigenc_unicode_get_case_fold_codes_by_str(OnigEncoding enc,
   n = 0;
 
   code = ONIGENC_MBC_TO_CODE(enc, p, end);
+  if (CASE_FOLD_IS_ASCII_ONLY(flag)) {
+    if (! ONIGENC_IS_ASCII_CODE(code)) return n;
+  }
   len = enclen(enc, p);
 
 #ifdef USE_UNICODE_CASE_FOLD_TURKISH_AZERI
@@ -449,19 +464,26 @@ onigenc_unicode_get_case_fold_codes_by_str(OnigEncoding enc,
   if (buk1 != 0) {
     if (buk1->fold_len == 1) {
       int un;
-      items[0].byte_len = lens[0];
-      items[0].code_len = 1;
-      items[0].code[0]  = *FOLDS1_FOLD(buk1->index);
-      n++;
+
+      if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) ||
+          ONIGENC_IS_ASCII_CODE(*FOLDS1_FOLD(buk1->index))) {
+        items[0].byte_len = lens[0];
+        items[0].code_len = 1;
+        items[0].code[0]  = *FOLDS1_FOLD(buk1->index);
+        n++;
+      }
 
       un = FOLDS1_UNFOLDS_NUM(buk1->index);
       for (i = 0; i < un; i++) {
         OnigCodePoint unfold = FOLDS1_UNFOLDS(buk1->index)[i];
         if (unfold != orig_codes[0]) {
-          items[n].byte_len = lens[0];
-          items[n].code_len = 1;
-          items[n].code[0]  = unfold;
-          n++;
+          if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag) ||
+              ONIGENC_IS_ASCII_CODE(unfold)) {
+            items[n].byte_len = lens[0];
+            items[n].code_len = 1;
+            items[n].code[0]  = unfold;
+            n++;
+          }
         }
       }
     }
@@ -548,10 +570,13 @@ onigenc_unicode_get_case_fold_codes_by_str(OnigEncoding enc,
     if (index >= 0) {
       int m = FOLDS1_UNFOLDS_NUM(index);
       for (i = 0; i < m; i++) {
-        items[n].byte_len = lens[0];
-        items[n].code_len = 1;
-        items[n].code[0]  = FOLDS1_UNFOLDS(index)[i];
-        n++;
+        code = FOLDS1_UNFOLDS(index)[i];
+        if (CASE_FOLD_IS_NOT_ASCII_ONLY(flag)||ONIGENC_IS_ASCII_CODE(code)) {
+          items[n].byte_len = lens[0];
+          items[n].code_len = 1;
+          items[n].code[0]  = code;
+          n++;
+        }
       }
     }
   }