diff options
Diffstat (limited to 'doc/RE')
| -rw-r--r-- | doc/RE | 225 |
1 files changed, 112 insertions, 113 deletions
@@ -1,35 +1,35 @@ -Oniguruma Regular Expressions Version 6.0.0 2016/05/02 +Oniguruma Regular Expressions Version 6.0.0 2016/08/18 syntax: ONIG_SYNTAX_RUBY (default) 1. Syntax elements - \ escape (enable or disable meta character meaning) + \ escape (enable or disable meta character) | alternation (...) group - [...] character class + [...] character class 2. Characters - \t horizontal tab (0x09) - \v vertical tab (0x0B) - \n newline (0x0A) - \r return (0x0D) - \b back space (0x08) - \f form feed (0x0C) - \a bell (0x07) - \e escape (0x1B) - \nnn octal char (encoded byte value) - \xHH hexadecimal char (encoded byte value) - \x{7HHHHHHH} wide hexadecimal char (character code point value) - \cx control char (character code point value) - \C-x control char (character code point value) - \M-x meta (x|0x80) (character code point value) - \M-\C-x meta control char (character code point value) - - (* \b is effective in character class [...] only) + \t horizontal tab (0x09) + \v vertical tab (0x0B) + \n newline (line feed) (0x0A) + \r carriage return (0x0D) + \b backspace (0x08) + \f form feed (0x0C) + \a bell (0x07) + \e escape (0x1B) + \nnn octal char (encoded byte value) + \xHH hexadecimal char (encoded byte value) + \x{7HHHHHHH} wide hexadecimal char (character code point value) + \cx control char (character code point value) + \C-x control char (character code point value) + \M-x meta (x|0x80) (character code point value) + \M-\C-x meta control char (character code point value) + + (* \b as backspace is effective in character class only) 3. Character types @@ -39,12 +39,12 @@ syntax: ONIG_SYNTAX_RUBY (default) \w word character Not Unicode: - alphanumeric, "_" and multibyte char. + alphanumeric, "_" and multibyte char. Unicode: General_Category -- (Letter|Mark|Number|Connector_Punctuation) - \W non word char + \W non-word char \s whitespace char @@ -52,22 +52,22 @@ syntax: ONIG_SYNTAX_RUBY (default) \t, \n, \v, \f, \r, \x20 Unicode: - 0009, 000A, 000B, 000C, 000D, 0085(NEL), + 0009, 000A, 000B, 000C, 000D, 0085(NEL), General_Category -- Line_Separator -- Paragraph_Separator -- Space_Separator - \S non whitespace char + \S non-whitespace char \d decimal digit char Unicode: General_Category -- Decimal_Number - \D non decimal digit char + \D non-decimal-digit char \h hexadecimal digit char [0-9a-fA-F] - \H non hexadecimal digit char + \H non-hexdigit char Character Property @@ -80,7 +80,7 @@ syntax: ONIG_SYNTAX_RUBY (default) + works on all encodings Alnum, Alpha, Blank, Cntrl, Digit, Graph, Lower, - Print, Punct, Space, Upper, XDigit, Word, ASCII, + Print, Punct, Space, Upper, XDigit, Word, ASCII + works on EUC_JP, Shift_JIS Hiragana, Katakana @@ -97,9 +97,9 @@ syntax: ONIG_SYNTAX_RUBY (default) ? 1 or 0 times * 0 or more times + 1 or more times - {n,m} at least n but not more than m times + {n,m} at least n but no more than m times {n,} at least n times - {,n} at least 0 but not more than n times ({0,n}) + {,n} at least 0 but no more than n times ({0,n}) {n} n times reluctant @@ -107,11 +107,11 @@ syntax: ONIG_SYNTAX_RUBY (default) ?? 1 or 0 times *? 0 or more times +? 1 or more times - {n,m}? at least n but not more than m times + {n,m}? at least n but not more than m times {n,}? at least n times {,n}? at least 0 but not more than n times (== {0,n}?) - possessive (greedy and does not backtrack after repeated) + possessive (greedy and does not backtrack once match) ?+ 1 or 0 times *+ 0 or more times @@ -127,24 +127,24 @@ syntax: ONIG_SYNTAX_RUBY (default) ^ beginning of the line $ end of the line \b word boundary - \B not word boundary + \B non-word boundary \A beginning of string \Z end of string, or before newline at the end \z end of string - \G matching start position + \G where the current search attempt begins 6. Character class - ^... negative class (lowest precedence operator) + ^... negative class (lowest precedence) x-y range from x to y [...] set (character class in character class) - ..&&.. intersection (low precedence at the next of ^) - + ..&&.. intersection (low precedence, only higher than ^) + ex. [a-w&&[^c-g]z] ==> ([a-w] AND ([^c-g] OR z)) ==> [abh-w] - * If you want to use '[', '-', ']' as a normal character - in a character class, you should escape these characters by '\'. + * If you want to use '[', '-', or ']' as a normal character + in character class, you should escape them with '\'. POSIX bracket ([:xxxxx:], negate [:^xxxxx:]) @@ -196,79 +196,75 @@ syntax: ONIG_SYNTAX_RUBY (default) (?imx-imx) option on/off i: ignore case - m: multi-line (dot(.) match newline) + m: multi-line (dot (.) also matches newline) x: extended form (?imx-imx:subexp) option on/off for subexp - (?:subexp) not captured group - (subexp) captured group + (?:subexp) non-capturing group + (subexp) capturing group (?=subexp) look-ahead (?!subexp) negative look-ahead (?<=subexp) look-behind (?<!subexp) negative look-behind - Subexp of look-behind must be fixed character length. - But different character length is allowed in top level - alternatives only. + Subexp of look-behind must be fixed-width. + But top-level alternatives can be of various lengths. ex. (?<=a|bc) is OK. (?<=aaa(?:b|cd)) is not allowed. - In negative-look-behind, captured group isn't allowed, - but shy group(?:) is allowed. + In negative look-behind, capturing group isn't allowed, + but non-capturing group (?:) is allowed. (?>subexp) atomic group - don't backtrack in subexp. + no backtracks in subexp. (?<name>subexp), (?'name'subexp) define named group - (All characters of the name must be a word character.) + (Each character of the name must be a word character.) - Not only a name but a number is assigned like a captured + Not only a name but a number is assigned like a capturing group. - Assigning the same name as two or more subexps is allowed. - In this case, a subexp call can not be performed although - the back reference is possible. + Assigning the same name to two or more subexps is allowed. + +8. Backreferences -8. Back reference + When we say "backreference a group," it actually means, "re-match the same + text matched by the subexp in that group." - \n back reference by group number (n >= 1) - \k<n> back reference by group number (n >= 1) - \k'n' back reference by group number (n >= 1) - \k<-n> back reference by relative group number (n >= 1) - \k'-n' back reference by relative group number (n >= 1) - \k<name> back reference by group name - \k'name' back reference by group name + \n \k<n> \k'n' (n >= 1) backreference the nth group in the regexp + \k<-n> \k'-n' (n >= 1) backreference the nth group counting + backwards from the referring position + \k<name> \k'name' backreference a group with the specified name - In the back reference by the multiplex definition name, - a subexp with a large number is referred to preferentially. - (When not matched, a group of the small number is referred to.) + When backreferencing with a name that is assigned to more than one groups, + the last group with the name is checked first, if not matched then the + previous one with the name, and so on, until there is a match. - * Back reference by group number is forbidden if named group is defined - in the pattern and ONIG_OPTION_CAPTURE_GROUP is not setted. + * Backreference by number is forbidden if any named group is defined and + ONIG_OPTION_CAPTURE_GROUP is not set. - back reference with nest level + backreference with recursion level - level: 0, 1, 2, ... + (n >= 1, level >= 0) - \k<n+level> (n >= 1) - \k<n-level> (n >= 1) - \k'n+level' (n >= 1) - \k'n-level' (n >= 1) + \k<n+level> \k'n+level' + \k<n-level> \k'n-level' - \k<name+level> - \k<name-level> - \k'name+level' - \k'name-level' + \k<name+level> \k'name+level' + \k<name-level> \k'name-level' - Destinate relative nest level from back reference position. + Destine a group on the recursion level relative to the referring position. ex 1. + /\A(?<a>|.|(?:(?<b>.)\g<a>\k<b>))\z/.match("reee") /\A(?<a>|.|(?:(?<b>.)\g<a>\k<b+0>))\z/.match("reer") + \k<b+0> refers to the (?<b>.) on the same recursion level with it. + ex 2. r = Regexp.compile(<<'__REGEXP__'.strip, Regexp::EXTENDED) @@ -280,53 +276,56 @@ syntax: ONIG_SYNTAX_RUBY (default) \g<element> __REGEXP__ - p r.match('<foo>f<bar>bbb</bar>f</foo>').captures + p r.match("<foo>f<bar>bbb</bar>f</foo>").captures + + +9. Subexp calls ("Tanaka Akira special") + When we say "call a group," it actually means, "re-execute the subexp in + that group." + \g<n> \g'n' (n >= 1) call the nth group + \g<-n> \g'-n' (n >= 1) call the nth group counting backwards from + the calling position + \g<name> \g'name' call the group with the specified name -9. Subexp call ("Tanaka Akira special") + * Left-most recursive calls are not allowed. - \g<name> call by group name - \g'name' call by group name - \g<n> call by group number (n >= 1) - \g'n' call by group number (n >= 1) - \g<-n> call by relative group number (n >= 1) - \g'-n' call by relative group number (n >= 1) + ex. (?<name>a|\g<name>b) => error + (?<name>a|b\g<name>c) => OK - * left-most recursive call is not allowed. - ex. (?<name>a|\g<name>b) => error - (?<name>a|b\g<name>c) => OK + * Calls with a name that is assigned to more than one groups are not + allowed. - * Call by group number is forbidden if named group is defined in the pattern - and ONIG_OPTION_CAPTURE_GROUP is not setted. + * Call by number is forbidden if any named group is defined and + ONIG_OPTION_CAPTURE_GROUP is not set. - * If the option status of called group is different from calling position - then the group's option is effective. + * The option status of the called group is always effective. - ex. (?-i:\g<name>)(?i:(?<name>a)){0} match to "A" + ex. /(?-i:\g<name>)(?i:(?<name>a)){0}/.match("A") 10. Captured group - Behavior of the no-named group (...) changes with the following conditions. + Behavior of an unnamed group (...) changes with the following conditions. (But named group is not changed.) case 1. /.../ (named group is not used, no option) - (...) is treated as a captured group. + (...) is treated as a capturing group. case 2. /.../g (named group is not used, 'g' option) - (...) is treated as a no-captured group (?:...). + (...) is treated as a non-capturing group (?:...). case 3. /..(?<name>..)../ (named group is used, no option) - (...) is treated as a no-captured group (?:...). + (...) is treated as a non-capturing group. numbered-backref/call is not allowed. case 4. /..(?<name>..)../G (named group is used, 'G' option) - (...) is treated as a captured group. + (...) is treated as a capturing group. numbered-backref/call is allowed. where @@ -338,14 +337,14 @@ syntax: ONIG_SYNTAX_RUBY (default) ----------------------------- -A-1. Syntax depend options +A-1. Syntax-dependent options + ONIG_SYNTAX_RUBY - (?m): dot(.) match newline + (?m): dot (.) also matches newline + ONIG_SYNTAX_PERL and ONIG_SYNTAX_JAVA - (?s): dot(.) match newline - (?m): ^ match after newline, $ match before newline + (?s): dot (.) also matches newline + (?m): ^ matches after newline, $ matches before newline A-2. Original extensions @@ -356,7 +355,7 @@ A-2. Original extensions + subexp call \g<name>, \g<group-num> -A-3. Lacked features compare with perl 5.8.0 +A-3. Missing features compared with perl 5.8.0 + \N{name} + \l,\u,\L,\U, \X, \C @@ -373,12 +372,12 @@ A-4. Differences with Japanized GNU regex(version 0.12) of Ruby 1.8 + add character property (\p{property}, \P{property}) + add hexadecimal digit char type (\h, \H) + add look-behind - (?<=fixed-char-length-pattern), (?<!fixed-char-length-pattern) + (?<=fixed-width-pattern), (?<!fixed-width-pattern) + add possessive quantifier. ?+, *+, ++ + add operations in character class. [], && ('[' must be escaped as an usual char in character class.) + add named group and subexp call. - + octal or hexadecimal number sequence can be treated as + + octal or hexadecimal number sequence can be treated as a multibyte code char in character class if multibyte encoding is specified. (ex. [\xa1\xa2], [\xa1\xa7-\xa4\xa1]) @@ -389,29 +388,29 @@ A-4. Differences with Japanized GNU regex(version 0.12) of Ruby 1.8 ex. (?:(?i)a|b) is interpreted as (?:(?i:a|b)), not (?:(?i:a)|b). + isolated option is not transparent to previous pattern. ex. a(?i)* is a syntax error pattern. - + allowed incompleted left brace as an usual string. + + allowed unpaired left brace as a normal character. ex. /{/, /({)/, /a{2,3/ etc... + negative POSIX bracket [:^xxxx:] is supported. + POSIX bracket [:ascii:] is added. + repeat of look-ahead is not allowed. ex. /(?=a)*/, /(?!b){5}/ - + Ignore case option is effective to numbered character. + + Ignore case option is effective to escape sequence. ex. /\x61/i =~ "A" - + In the range quantifier, the number of the minimum is omissible. + + In the range quantifier, the number of the minimum is optional. /a{,n}/ == /a{0,n}/ - The simultanious abbreviation of the number of times of the minimum - and the maximum is not allowed. (/a{,}/) - + /a{n}?/ is not a non-greedy operator. + The omission of both minimum and maximum values is not allowed. + /a{,}/ + + /{n}?/ is not a reluctant quantifier. /a{n}?/ == /(?:a{n})?/ - + invalid back reference is checked and cause error. + + invalid back reference is checked and raises error. /\1/, /(a)\2/ - + Zero-length match in infinite repeat stops the repeat, + + Zero-width match in an infinite loop stops the repeat, then changes of the capture group status are checked as stop condition. /(?:()|())*\1\2/ =~ "" /(?:\1a|())*/ =~ "a" -A-5. Disabled functions by default syntax +A-5. Features disabled in default syntax + capture history |