Imported Upstream version 3.3.0.2upstream/3.3.0.2

13 files changed, 2203 insertions, 0 deletions

diff --git a/libbackend-elements/backend-elements/indentation/buffer.hxx b/libbackend-elements/backend-elements/indentation/buffer.hxx
new file mode 100644
index 0000000..7058814
--- /dev/null
+++ b/libbackend-elements/backend-elements/indentation/buffer.hxx
@@ -0,0 +1,61 @@
+// file      : backend-elements/indentation/buffer.hxx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+#ifndef BACKEND_ELEMENTS_INDENTATION_BUFFER_HXX
+#define BACKEND_ELEMENTS_INDENTATION_BUFFER_HXX
+
+#include <backend-elements/types.hxx>
+
+#include <string>
+
+namespace BackendElements
+{
+  namespace Indentation
+  {
+    template <typename C>
+    class Buffer: public NonCopyable
+    {
+    public:
+      struct Write {};
+
+    public:
+      virtual
+      ~Buffer ()
+      {
+      }
+
+    public:
+      typedef
+      std::char_traits<C>
+      Traits;
+
+      typedef
+      typename Traits::char_type
+      AsChar;
+
+      typedef
+      typename Traits::int_type
+      AsInt;
+
+    public:
+      virtual AsInt
+      put (AsChar c) = 0;
+
+      // Unbuffer flushes internal formatting buffers (if any).
+      // Note that unbuffer is not exactly flushing since it can
+      // result in formatting errors and in general can not be
+      // called at arbitrary points. Natural use case would be
+      // to call unbuffer at the end of the stream when no more
+      // data is expected.
+      //
+      virtual Void
+      unbuffer () = 0;
+    };
+  }
+}
+
+#include <backend-elements/indentation/buffer.txx>
+
+#endif  // BACKEND_ELEMENTS_INDENTATION_BUFFER_HXX
diff --git a/libbackend-elements/backend-elements/indentation/buffer.txx b/libbackend-elements/backend-elements/indentation/buffer.txx
new file mode 100644
index 0000000..57ba7ab
--- /dev/null
+++ b/libbackend-elements/backend-elements/indentation/buffer.txx
@@ -0,0 +1,12 @@
+// file      : backend-elements/indentation/buffer.txx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+namespace BackendElements
+{
+  namespace Indentation
+  {
+  }
+}
+
diff --git a/libbackend-elements/backend-elements/indentation/clip.hxx b/libbackend-elements/backend-elements/indentation/clip.hxx
new file mode 100644
index 0000000..068ed0d
--- /dev/null
+++ b/libbackend-elements/backend-elements/indentation/clip.hxx
@@ -0,0 +1,173 @@
+// file      : backend-elements/indentation/clip.hxx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+#ifndef BACKEND_ELEMENTS_INDENTATION_CLIP_HXX
+#define BACKEND_ELEMENTS_INDENTATION_CLIP_HXX
+
+#include <backend-elements/types.hxx>
+
+#include <backend-elements/indentation/buffer.hxx>
+
+#include <ostream>
+
+namespace BackendElements
+{
+  namespace Indentation
+  {
+    template <typename C>
+    class ToStreambufAdapter: public std::basic_streambuf<C>,
+                              public NonCopyable
+    {
+    public:
+      typedef
+      typename std::basic_streambuf<C>::traits_type
+      Traits;
+
+      typedef
+      typename std::basic_streambuf<C>::char_type
+      AsChar;
+
+      typedef
+      typename std::basic_streambuf<C>::int_type
+      AsInt;
+
+    public:
+      ToStreambufAdapter (Buffer<C>& buffer)
+          : buffer_ (buffer)
+      {
+      }
+
+      virtual AsInt
+      overflow (AsInt ch)
+      {
+        return buffer_.put (Traits::to_char_type (ch));
+      }
+
+      virtual Int
+      sync ()
+      {
+        return 0;
+      }
+
+    private:
+      Buffer<C>& buffer_;
+    };
+
+
+    template <typename C>
+    class FromStreambufAdapter: public Buffer<C>
+    {
+    public:
+      typedef
+      typename Buffer<C>::Traits
+      Traits;
+
+      typedef
+      typename Buffer<C>::AsChar
+      AsChar;
+
+      typedef
+      typename Buffer<C>::AsInt
+      AsInt;
+
+      typedef
+      typename Buffer<C>::Write
+      Write;
+
+    public:
+      FromStreambufAdapter (std::basic_streambuf<C>& b)
+          : buffer_ (b)
+      {
+      }
+
+      virtual AsInt
+      put (AsChar ch)
+      {
+        return buffer_.sputc (ch);
+      }
+
+      virtual Void
+      unbuffer ()
+      {
+        try
+        {
+          if (buffer_.pubsync () == 0) return;
+        }
+        catch (std::ios_base::failure const&)
+        {
+        }
+
+        throw Write ();
+      }
+
+    private:
+      std::basic_streambuf<C>& buffer_;
+    };
+
+
+    template <template <typename> class Buffer, typename C = Char>
+    class Clip: public NonCopyable
+    {
+    public:
+      Clip (std::basic_ostream<C>& os)
+          : os_ (os),
+            prev_ (os_.rdbuf ()),
+            from_adapter_ (*prev_),
+            buffer_ (from_adapter_),
+            to_adapter_ (buffer_)
+      {
+        os_.rdbuf (&to_adapter_);
+      }
+
+      /*
+      template <typename Arg0>
+      Clip (std::basic_ostream<C>& os, Arg0 a0)
+          : os_ (os),
+            prev_ (os_.rdbuf ()),
+            from_adapter_ (*prev_),
+            buffer_ (from_adapter_, a0),
+            to_adapter_ (buffer_)
+      {
+        os_.rdbuf (&to_adapter_);
+      }
+      */
+
+      ~Clip ()
+      {
+        try
+        {
+          buffer_.unbuffer ();
+        }
+        catch (...)
+        {
+          os_.rdbuf (prev_);
+          throw;
+        }
+
+        os_.rdbuf (prev_);
+      }
+
+      Buffer<C>&
+      buffer ()
+      {
+        return buffer_;
+      }
+
+    private:
+      std::basic_ostream<C>& os_;
+      std::basic_streambuf<C>* prev_;
+
+      FromStreambufAdapter<C> from_adapter_;
+
+      Buffer<C> buffer_;
+
+      ToStreambufAdapter<C> to_adapter_;
+    };
+  }
+}
+
+#include <backend-elements/indentation/clip.txx>
+
+#endif  // BACKEND_ELEMENTS_INDENTATION_CLIP_HXX
diff --git a/libbackend-elements/backend-elements/indentation/clip.txx b/libbackend-elements/backend-elements/indentation/clip.txx
new file mode 100644
index 0000000..58112f1
--- /dev/null
+++ b/libbackend-elements/backend-elements/indentation/clip.txx
@@ -0,0 +1,12 @@
+// file      : backend-elements/indentation/clip.txx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+namespace BackendElements
+{
+  namespace Indentation
+  {
+  }
+}
+
diff --git a/libbackend-elements/backend-elements/indentation/cxx.hxx b/libbackend-elements/backend-elements/indentation/cxx.hxx
new file mode 100644
index 0000000..f10341a
--- /dev/null
+++ b/libbackend-elements/backend-elements/indentation/cxx.hxx
@@ -0,0 +1,1016 @@
+// file      : backend-elements/indentation/cxx.hxx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+#ifndef BACKEND_ELEMENTS_INDENTATION_CXX_HXX
+#define BACKEND_ELEMENTS_INDENTATION_CXX_HXX
+
+#include <backend-elements/types.hxx>
+#include <backend-elements/indentation/buffer.hxx>
+
+#include <cult/containers/set.hxx>
+#include <cult/containers/stack.hxx>
+#include <cult/containers/deque.hxx>
+
+#include <locale>
+
+// #include <iostream> // @@ tmp
+
+namespace BackendElements
+{
+  namespace Indentation
+  {
+    template <typename C>
+    class CXX: public Buffer<C>/*, public NonCopyable*/
+    {
+    public:
+      typedef
+      typename Buffer<C>::Traits
+      Traits;
+
+      typedef
+      typename Buffer<C>::AsChar
+      AsChar;
+
+      typedef
+      typename Buffer<C>::AsInt
+      AsInt;
+
+      typedef
+      typename Buffer<C>::Write
+      Write;
+
+    public:
+      CXX (Buffer<C>& out)
+          : out_ (out),
+            buffering_ (false),
+            position_ (0),
+            paren_balance_ (0),
+            spaces_ (2),
+            construct_ (Construct::other),
+            lbrace_ ("{"),
+            rbrace_ ("}")
+        // locale_ ("C")
+      {
+        indentation_.push (0);
+
+        single_line_blocks_.insert ("if");
+        single_line_blocks_.insert ("do");
+        single_line_blocks_.insert ("for");
+        single_line_blocks_.insert ("else");
+        single_line_blocks_.insert ("case");
+        single_line_blocks_.insert ("while");
+
+        follow_blocks_.insert ("else");
+        follow_blocks_.insert ("case");
+        follow_blocks_.insert ("catch");
+        follow_blocks_.insert ("default");
+      }
+
+    public:
+      virtual AsInt
+      put (AsChar c)
+      {
+        AsInt result (Traits::to_int_type (c));
+
+        try
+        {
+          // First determine what kind of construct we are in.
+          //
+          typename Construct::Value new_construct (construct_);
+          typename Construct::Value old_construct (construct_);
+
+          switch (c)
+          {
+          case '\n':
+            {
+              if (construct_ == Construct::pp_directive ||
+                  construct_ == Construct::cxx_comment)
+                construct_ = new_construct = Construct::other;
+
+              break;
+            }
+          case '#':
+            {
+              if (construct_ == Construct::other)
+                construct_ = new_construct = Construct::pp_directive;
+
+              break;
+            }
+          case '\"':
+            {
+              if (construct_ != Construct::pp_directive &&
+                  construct_ != Construct::c_comment &&
+                  construct_ != Construct::cxx_comment &&
+                  construct_ != Construct::char_literal)
+              {
+                // We might be in an escape sequence.
+                //
+                Boolean es (!hold_.empty () && hold_.back () == '\\');
+
+                if (es)
+                {
+                  // Scan the hold sequence backwards to figure out if this
+                  // backslash is part of this escape sequence or a preceding
+                  // one.
+                  //
+                  for (typename Hold::ReverseIterator i (hold_.rbegin () + 1),
+                         e (hold_.rend ()); i != e && *i == '\\'; ++i)
+                    es = !es;
+                }
+
+                if (!es)
+                {
+                  // Not an escape sequence.
+                  //
+                  if (construct_ == Construct::string_literal)
+                    new_construct = Construct::other;
+                  else
+                    construct_ = new_construct = Construct::string_literal;
+                }
+              }
+
+              break;
+            }
+          case '\'':
+            {
+              if (construct_ != Construct::pp_directive &&
+                  construct_ != Construct::c_comment &&
+                  construct_ != Construct::cxx_comment &&
+                  construct_ != Construct::string_literal)
+              {
+                // We might be in an escape sequence.
+                //
+                Boolean es (!hold_.empty () && hold_.back () == '\\');
+
+                if (es)
+                {
+                  // Scan the hold sequence backwards to figure out if this
+                  // backslash is part of this escape sequence or a preceding
+                  // one.
+                  //
+                  for (typename Hold::ReverseIterator i (hold_.rbegin () + 1),
+                         e (hold_.rend ()); i != e && *i == '\\'; ++i)
+                    es = !es;
+                }
+
+                if (!es)
+                {
+                  if (construct_ == Construct::char_literal)
+                    new_construct = Construct::other;
+                  else
+                    construct_ = new_construct = Construct::char_literal;
+                }
+              }
+
+              break;
+            }
+          case '/':
+            {
+              if (construct_ == Construct::other)
+              {
+                if (!hold_.empty () && hold_.back () == '/')
+                  construct_ = new_construct = Construct::cxx_comment;
+              }
+
+              if (construct_ == Construct::c_comment)
+              {
+                if (!hold_.empty () && hold_.back () == '*')
+                  construct_ = new_construct = Construct::other;
+              }
+
+              break;
+            }
+          case '*':
+            {
+              if (construct_ == Construct::other)
+              {
+                if (!hold_.empty () && hold_.back () == '/')
+                  construct_ = new_construct = Construct::c_comment;
+              }
+
+              break;
+            }
+          default:
+            {
+              break;
+            }
+          }
+
+          // Special handling of CPP directives.
+          //
+          if (construct_ == Construct::pp_directive)
+          {
+            result = write (c);
+            position_++;
+            return result;
+          }
+
+          //
+          //
+          tokenize (c, old_construct);
+
+
+          // Indentation in parenthesis. We don't need to make sure
+          // we are not in a comments, etc. because we make sure we
+          // don't hold anything in those states.
+          //
+          if (!hold_.empty () && hold_.back () == '(')
+          {
+            unbuffer (); // We don't need to hold it anymore.
+
+            if (c == '\n')
+              indentation_.push (indentation_.top () + spaces_);
+            else
+              indentation_.push (position_);
+          }
+
+
+          //
+          //
+          Boolean defaulting (false);
+
+          switch (c)
+          {
+          case '\n':
+            {
+              if (!indent_block_.empty () && construct_ == Construct::other)
+                indent_block_.top ().newline_ = true;
+
+              hold_.push_back (c);
+              position_ = 0; // Starting a new line.
+
+              break;
+            }
+          case '{':
+            {
+              if (construct_ == Construct::other)
+              {
+                if (!indent_block_.empty ())
+                {
+                  // Pop all the blocks until the one that was indented.
+                  //
+                  while (!indent_block_.top ().indented_)
+                    indent_block_.pop ();
+
+                  if (indentation_.size () > 1)
+                    indentation_.pop ();
+
+                  indent_block_.pop ();
+                }
+
+                ensure_new_line ();
+                output_indentation ();
+                result = write (c);
+                ensure_new_line ();
+
+                indentation_.push (indentation_.top () + spaces_);
+              }
+              else
+                defaulting = true;
+
+              break;
+            }
+          case '}':
+            {
+              if (construct_ == Construct::other)
+              {
+                if (indentation_.size () > 1)
+                  indentation_.pop ();
+
+                // Reduce multiple newlines to one.
+                //
+                while (hold_.size () > 1)
+                {
+                  typename Hold::ReverseIterator i (hold_.rbegin ());
+
+                  if (*i == '\n' && *(i + 1) == '\n')
+                    hold_.pop_back ();
+                  else
+                    break;
+                }
+
+                ensure_new_line ();
+                output_indentation ();
+
+                hold_.push_back (c);
+
+
+                // Add double newline after '}'.
+                //
+                hold_.push_back ('\n');
+                hold_.push_back ('\n');
+                position_ = 0;
+
+                buffering_ = true;
+              }
+              else
+                defaulting = true;
+
+              break;
+            }
+          case ';':
+            {
+              if (construct_ == Construct::other)
+              {
+                // for (;;)
+                //
+                if (!indent_block_.empty () && paren_balance_ == 0)
+                {
+                  // Pop all the blocks until the one that was indented.
+                  //
+                  while (!indent_block_.top ().indented_)
+                    indent_block_.pop ();
+
+                  if (indentation_.size () > 1)
+                    indentation_.pop ();
+
+                  indent_block_.pop ();
+                }
+
+                if (paren_balance_ != 0)
+                {
+                  // We are inside for (;;) statement. Nothing to do here.
+                  //
+                  defaulting = true;
+                }
+                else
+                {
+                  // Handling '};' case.
+                  //
+
+                  Boolean brace (false);
+
+                  if (hold_.size () > 1 && hold_.back () == '\n')
+                  {
+                    Boolean pop_nl (false);
+
+                    for (typename Hold::ReverseIterator
+                           i (hold_.rbegin ()), e (hold_.rend ());
+                         i != e; ++i)
+                    {
+                      if (*i != '\n')
+                      {
+                        if (*i == '}')
+                          brace = pop_nl = true;
+
+                        break;
+                      }
+                    }
+
+                    if (pop_nl)
+                      while (hold_.back () == '\n')
+                        hold_.pop_back ();
+                  }
+
+                  output_indentation ();
+                  result = write (c);
+                  position_++;
+
+                  if (brace)
+                  {
+                    hold_.push_back ('\n');
+                    hold_.push_back ('\n');
+                  }
+
+                  ensure_new_line ();
+                }
+              }
+              else
+                defaulting = true;
+
+              break;
+            }
+          case ' ':
+            {
+              if (construct_ == Construct::other)
+              {
+                // Handling '} foo_;' case.
+                //
+                if (hold_.size () > 1 && hold_.back () == '\n')
+                {
+                  Boolean pop_nl (false);
+
+                  for (typename Hold::ReverseIterator
+                         i (hold_.rbegin ()), e (hold_.rend ());
+                       i != e; ++i)
+                  {
+                    if (*i != '\n')
+                    {
+                      if (*i == '}')
+                        pop_nl = true;
+
+                      break;
+                    }
+                  }
+
+                  if (pop_nl)
+                    while (hold_.back () == '\n')
+                      hold_.pop_back ();
+                }
+              }
+
+              defaulting = true;
+              break;
+            }
+          case '\\':
+            {
+              if (construct_ != Construct::pp_directive &&
+                  construct_ != Construct::c_comment &&
+                  construct_ != Construct::cxx_comment)
+              {
+                output_indentation ();
+                hold_.push_back (c);
+                position_++;
+              }
+              else
+                defaulting = true;
+
+            break;
+
+            }
+          case '(':
+            {
+              if (construct_ == Construct::other)
+              {
+                // Hold it so that we can see what's coming next.
+                //
+                output_indentation ();
+                hold_.push_back (c);
+                position_++;
+                paren_balance_++;
+              }
+              else
+                defaulting = true;
+              break;
+            }
+          case ')':
+            {
+              if (construct_ == Construct::other)
+              {
+                if (indentation_.size () > 1)
+                  indentation_.pop ();
+
+                if (paren_balance_ > 0)
+                  paren_balance_--;
+              }
+
+              defaulting = true;
+              break;
+            }
+          case '/':
+            {
+              if (construct_ == Construct::other)
+              {
+                output_indentation ();
+                hold_.push_back (c);
+                position_++;
+              }
+              else
+                defaulting = true;
+
+              break;
+            }
+          case '*':
+            {
+              if (construct_ == Construct::c_comment)
+              {
+                output_indentation ();
+                hold_.push_back (c);
+                position_++;
+              }
+              else
+                defaulting = true;
+
+              break;
+            }
+          default:
+            {
+              defaulting = true;
+              break;
+            }
+          }
+
+
+          if (defaulting)
+          {
+            output_indentation ();
+            result = write (c);
+            position_++;
+          }
+
+          construct_ = new_construct;
+        }
+        catch (Write const&)
+        {
+          result = Traits::eof ();
+        }
+
+        return result;
+      }
+
+    private:
+      typedef Cult::StringTemplate<C> String;
+
+      Void
+      next_token (String const& old, AsChar c)
+      {
+        //std::cerr << "next token: " << token_
+        //          << "; old token: " << old << std::endl;
+
+        // Handle one line indentation blocks (if, else, etc).
+        //
+        if (single_line_blocks_.find (token_) != single_line_blocks_.end ())
+        {
+          // Only indent sub-blocks if we are on a new line.
+          //
+          Boolean indent (indent_block_.empty () ||
+                          indent_block_.top ().newline_);
+
+          indent_block_.push (IndentBlockInfo (c == '\n', indent));
+
+          if (indent)
+            indentation_.push (indentation_.top () + spaces_);
+        }
+
+        // Keep track of the do ... while construct in order to suppress
+        // the newline after } and before while.
+        //
+        if (old == String ("do") && token_ == lbrace_)
+        {
+          do_while_state_.push (0);
+        }
+
+        if (!do_while_state_.empty ())
+        {
+          if (token_ == lbrace_)
+            do_while_state_.top ()++;
+
+          if (token_ == rbrace_)
+            do_while_state_.top ()--;
+        }
+
+        // Suppress double newline in the "}else", etc., cases.
+        //
+        if (old == rbrace_)
+        {
+          Boolean dw (!do_while_state_.empty () &&
+                      do_while_state_.top () == 0);
+
+          if (follow_blocks_.find (token_) != follow_blocks_.end () || dw)
+          {
+            if (dw)
+              do_while_state_.pop ();
+
+            // Reduce double newline after "}" into a single one.
+            //
+            typename Hold::Iterator i (hold_.end ()), b (hold_.begin ());
+
+            for (--i; i != b; --i)
+            {
+              // See if this is the end of the "}\n\n" sequence.
+              //
+              if (*i == '\n')
+              {
+                --i;
+                if (i != b && *i == '\n')
+                {
+                  --i;
+                  if (*i == '}')
+                  {
+                    ++i;
+                    hold_.erase (i);
+                    break;
+                  }
+                }
+              }
+            }
+          }
+          else if (token_ != rbrace_)
+          {
+            buffering_ = false;
+          }
+        }
+      }
+
+    public:
+      virtual Void
+      unbuffer ()
+      {
+        AsInt result;
+
+        while (!hold_.empty ())
+        {
+          result = out_.put (hold_.front ());
+
+          //@@ failed
+          if (result == Traits::eof ())
+            throw Write ();
+
+          hold_.pop_front ();
+        }
+      }
+
+    private:
+      Void
+      ensure_new_line ()
+      {
+        if (hold_.empty () || hold_.back () != '\n')
+        {
+          hold_.push_back ('\n');
+          position_ = 0; // Starting a new line.
+        }
+      }
+
+
+      Void
+      output_indentation ()
+      {
+        if (!hold_.empty () && hold_.back () == '\n')
+        {
+          for (UnsignedLong i (0); i < indentation_.top (); ++i)
+            write (' ');
+
+          position_ += indentation_.top ();
+        }
+      }
+
+      AsInt
+      write (AsChar c)
+      {
+        hold_.push_back (c);
+
+        if (!buffering_)
+        {
+          AsInt result (Traits::eof ());
+
+          while (!hold_.empty ())
+          {
+            result = out_.put (hold_.front ());
+
+            if (result == Traits::eof ())
+              throw Write ();
+
+            hold_.pop_front ();
+          }
+
+          return result;
+        }
+        else
+          return c;
+      }
+
+    private:
+      struct Construct
+      {
+        enum Value
+        {
+          other,
+          pp_directive,
+          c_comment,
+          cxx_comment,
+          string_literal,
+          char_literal
+        };
+      };
+
+      Void
+      tokenize (AsChar c, typename Construct::Value old)
+      {
+        //
+        //
+        switch (construct_)
+        {
+        case Construct::pp_directive:
+          {
+            if (old == Construct::other) // Start PP directive
+              retire (c);
+
+            return;
+          }
+        case Construct::c_comment:
+          {
+            if (old == Construct::other) // Start C comment.
+              lexeme_.clear ();
+
+            return;
+          }
+        case Construct::cxx_comment:
+          {
+            if (old == Construct::other) // Start C++ comment.
+              lexeme_.clear ();
+
+            return;
+          }
+        case Construct::string_literal:
+          {
+            if (old == Construct::other) // Start string literal
+              retire (c);
+
+            lexeme_ += c;
+            return;
+          }
+        case Construct::char_literal:
+          {
+            if (old == Construct::other) // Start char literal
+              retire (c);
+
+            lexeme_ += c;
+            return;
+          }
+        default:
+          break;
+        }
+
+        // construct_ == other
+        //
+        switch (old)
+        {
+        case Construct::pp_directive:
+          {
+            // End  PP directive (newline).
+            //
+            return;
+          }
+        case Construct::c_comment:
+          {
+            // End  C comment.
+            //
+            return;
+          }
+        case Construct::cxx_comment:
+          {
+            // End  C++ comment (newline).
+            //
+            return;
+          }
+        case Construct::string_literal:
+          {
+            // End string literal (").
+            //
+            lexeme_ += c;
+            return;
+          }
+        case Construct::char_literal:
+          {
+            // End char literal (').
+            //
+            lexeme_ += c;
+            return;
+          }
+        default:
+          break;
+        }
+
+
+        // construct_ == old == other
+        //
+
+        /*
+
+        The code below is equivalent to this (simpler) code which is
+        unfortunately not fast enough.
+
+        using std::isalpha;
+        using std::isalnum;
+        using std::isdigit;
+        using std::isspace;
+
+        if (c == '_' || isalpha (c, locale_))
+        {
+          if (lexeme_.empty () ||
+              lexeme_[0] == '_' || isalpha (lexeme_[0], locale_))
+            lexeme_ += c;
+          else
+          {
+            retire (c);
+            lexeme_ += c;
+          }
+        }
+        else if (isdigit (c, locale_))
+        {
+          if (lexeme_.empty () ||
+              lexeme_[0] == '_' || isalnum (lexeme_[0], locale_))
+            lexeme_ += c;
+          else
+          {
+            retire (c);
+            lexeme_ += c;
+          }
+        }
+        else // Delimiters
+        {
+          retire (c);
+
+          if (!isspace (c, locale_))
+            lexeme_ += c;
+        }
+        */
+
+        switch (char_class (c))
+        {
+        case CharClass::alpha:
+          {
+            if (lexeme_.empty () ||
+                char_class (lexeme_[0]) == CharClass::alpha)
+              lexeme_ += c;
+            else
+            {
+              retire (c);
+              lexeme_ += c;
+            }
+            break;
+          }
+        case CharClass::digit:
+          {
+            if (lexeme_.empty ())
+              lexeme_ += c;
+            else
+            {
+              typename CharClass::Value cc (char_class (lexeme_[0]));
+
+              if (cc == CharClass::alpha || cc == CharClass::digit)
+                lexeme_ += c;
+              else
+              {
+                retire (c);
+                lexeme_ += c;
+              }
+            }
+            break;
+          }
+        case CharClass::op_punc:
+          {
+            retire (c);
+            lexeme_ += c;
+            break;
+          }
+        case CharClass::space:
+          {
+            retire (c);
+            break;
+          }
+        }
+      }
+
+      struct CharClass
+      {
+        enum Value
+        {
+          alpha,   // Alpha + '_'.
+          digit,
+          op_punc, // Operator or punctuation.
+          space
+        };
+
+      };
+
+      typename CharClass::Value
+      char_class (C c)
+      {
+        switch (c)
+        {
+        case '0':
+        case '1':
+        case '2':
+        case '3':
+        case '4':
+        case '5':
+        case '6':
+        case '7':
+        case '8':
+        case '9':
+          return CharClass::digit;
+
+        case '!':
+        case '%':
+        case '^':
+        case '&':
+        case '*':
+        case '(':
+        case ')':
+        case '-':
+        case '+':
+        case '=':
+        case '{':
+        case '}':
+        case '|':
+        case '~':
+        case '[':
+        case ']':
+        case '\\':
+        case ';':
+        case '\'':
+        case ':':
+        case '"':
+        case '<':
+        case '>':
+        case '?':
+        case ',':
+        case '.':
+        case '/':
+          return CharClass::op_punc;
+
+        case ' ':
+        case '\n':
+        case '\t':
+        case '\f':
+        case '\r':
+        case '\v':
+          return CharClass::space;
+
+        default:
+          return CharClass::alpha;
+        }
+      }
+
+
+      Void
+      retire (AsChar c)
+      {
+        if (!lexeme_.empty ())
+        {
+          token_.swap (lexeme_);
+          next_token (lexeme_, c);
+          lexeme_.clear ();
+        }
+      }
+
+    private:
+      Buffer<C>& out_;
+      Boolean buffering_; // True if write() should buffer the char.
+      UnsignedLong position_; // Current position on the line.
+      UnsignedLong paren_balance_; // ( ) balance.
+      Cult::Containers::Stack<UnsignedLong> indentation_;
+      UnsignedLong spaces_;
+
+      Boolean suppress_nl_;
+
+      //@@ gcc bug# 18304
+      //
+      typename Construct::Value construct_;
+
+      // Special state stach for the do-while construct. The presence
+      // of an element in the stack indicates that we are in a braced
+      // do-while construct. The value of the element is the brace
+      // balance.
+      Cult::Containers::Stack<UnsignedLong> do_while_state_;
+
+      typedef
+      Cult::Containers::Deque<AsInt>
+      Hold;
+
+      Hold hold_;
+
+    private:
+      String token_;  // previously fully recognized token
+      String lexeme_; // current lexeme (accumulator)
+
+      // std::locale locale_;
+
+      // Keywords that may be folowed by a single-line block, e.g., if,
+      // else, etc.
+      //
+      Cult::Containers::Set<String> single_line_blocks_;
+
+      // Keywords that may follow (and be related) to a previous block,
+      // e.g., else, case, catch.
+      //
+      Cult::Containers::Set<String> follow_blocks_;
+
+      String lbrace_;
+      String rbrace_;
+
+    private:
+      // Single-line indented blocks such as if, else, while, etc. The
+      // newline flag indicates whether a new line has been seen after
+      // the keyword. This is needed to properly distinguish cases such
+      // as:
+      //
+      // else if (...)
+      //   foo ();
+      //
+      // else
+      //   if (...)
+      //     foo ();
+      //
+      struct IndentBlockInfo
+      {
+        IndentBlockInfo (Boolean newline, Boolean indented)
+            : newline_ (newline), indented_ (indented)
+        {
+        }
+
+        Boolean newline_;
+        Boolean indented_;
+      };
+
+      Cult::Containers::Stack<IndentBlockInfo> indent_block_;
+    };
+  }
+}
+
+#include <backend-elements/indentation/cxx.txx>
+
+#endif  // BACKEND_ELEMENTS_INDENTATION_CXX_HXX
diff --git a/libbackend-elements/backend-elements/indentation/cxx.txx b/libbackend-elements/backend-elements/indentation/cxx.txx
new file mode 100644
index 0000000..9acff37
--- /dev/null
+++ b/libbackend-elements/backend-elements/indentation/cxx.txx
@@ -0,0 +1,12 @@
+// file      : backend-elements/indentation/cxx.txx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+namespace BackendElements
+{
+  namespace Indentation
+  {
+  }
+}
+
diff --git a/libbackend-elements/backend-elements/indentation/idl.hxx b/libbackend-elements/backend-elements/indentation/idl.hxx
new file mode 100644
index 0000000..e5a234f
--- /dev/null
+++ b/libbackend-elements/backend-elements/indentation/idl.hxx
@@ -0,0 +1,290 @@
+// file      : backend-elements/indentation/idl.hxx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+#ifndef BACKEND_ELEMENTS_INDENTATION_IDL_HXX
+#define BACKEND_ELEMENTS_INDENTATION_IDL_HXX
+
+#include <backend-elements/types.hxx>
+#include <backend-elements/indentation/buffer.hxx>
+
+#include <cult/containers/deque.hxx>
+
+namespace BackendElements
+{
+  namespace Indentation
+  {
+    template <typename C>
+    class IDL: public Buffer<C>, public NonCopyable
+    {
+    public:
+      typedef
+      typename Buffer<C>::Traits
+      Traits;
+
+      typedef
+      typename Buffer<C>::AsChar
+      AsChar;
+
+      typedef
+      typename Buffer<C>::AsInt
+      AsInt;
+
+      typedef
+      typename Buffer<C>::Write
+      Write;
+
+    public:
+      IDL (Buffer<C>& out)
+          : out_ (out),
+            indentation_ (0),
+            spaces_ (2),
+            construct_ (Construct::other)
+      {
+      }
+
+    public:
+      virtual AsInt
+      put (AsChar c)
+      {
+        AsInt result (Traits::to_int_type (c));
+
+        try
+        {
+          Boolean defaulting (false);
+
+          switch (c)
+          {
+          case '\n':
+            {
+              hold_.push_back (c);
+              break;
+            }
+          case '{':
+            {
+              ensure_new_line ();
+              output_indentation ();
+              result = write (c);
+              ensure_new_line ();
+              indentation_++;
+              break;
+            }
+          case '}':
+            {
+              if (indentation_ > 0) indentation_--;
+
+              // Reduce multiple newlines to one.
+              //
+              while (hold_.size () > 1)
+              {
+                typename Hold::ReverseIterator i (hold_.rbegin ());
+
+                if (*i == '\n' && *(i + 1) == '\n')
+                  hold_.pop_back ();
+                else
+                  break;
+              }
+
+              ensure_new_line ();
+              output_indentation ();
+
+              hold_.push_back (c);
+
+              // Add double newline after '}'.
+              //
+              hold_.push_back ('\n');
+              hold_.push_back ('\n');
+
+
+              break;
+            }
+          case ';':
+            {
+              // Handling '};' case.
+              //
+
+              Boolean brace (false);
+
+              if (hold_.size () > 1 && hold_.back () == '\n')
+              {
+                Boolean pop_nl (false);
+
+                for (typename Hold::ReverseIterator
+                       i (hold_.rbegin ()), e (hold_.rend ()); i != e; ++i)
+                {
+                  if (*i != '\n')
+                  {
+                    if (*i == '}')
+                      brace = pop_nl = true;
+
+                    break;
+                  }
+                }
+
+                if (pop_nl)
+                  while (hold_.back () == '\n')
+                    hold_.pop_back ();
+              }
+
+              output_indentation ();
+              result = write (c);
+
+              if (brace)
+              {
+                hold_.push_back ('\n');
+                hold_.push_back ('\n');
+              }
+
+              if (construct_ != Construct::string_literal &&
+                  construct_ != Construct::char_literal)
+              {
+                ensure_new_line ();
+              }
+              break;
+            }
+          case '\\':
+            {
+              hold_.push_back (c);
+              break;
+            }
+          case '\"':
+            {
+              if (hold_.empty () || hold_.back () != '\\')
+              {
+                // not escape sequence
+                if (construct_ == Construct::string_literal)
+                {
+                  construct_ = Construct::other;
+                }
+                else construct_ = Construct::string_literal;
+              }
+
+              defaulting = true;
+              break;
+            }
+          case '\'':
+            {
+              if (hold_.empty () || hold_.back () != '\\')
+              {
+                // not escape sequence
+                if (construct_ == Construct::char_literal)
+                {
+                  construct_ = Construct::other;
+                }
+                else construct_ = Construct::char_literal;
+              }
+
+              defaulting = true;
+              break;
+            }
+          default:
+            {
+              defaulting = true;
+              break;
+            }
+          }
+
+          if (defaulting)
+          {
+            output_indentation ();
+            result = write (c);
+          }
+        }
+        catch (Write const&)
+        {
+          result = Traits::eof ();
+        }
+
+        return result;
+      }
+
+      virtual Void
+      unbuffer ()
+      {
+        AsInt result;
+
+        while (!hold_.empty ())
+        {
+          result = out_.put (hold_.front ());
+
+          //@@ failed
+          if (result == Traits::eof ())
+            throw Write ();
+
+          hold_.pop_front ();
+        }
+      }
+
+    private:
+      Void
+      ensure_new_line ()
+      {
+        if (hold_.empty () || hold_.back () != '\n')
+          hold_.push_back ('\n');
+      }
+
+
+      Void
+      output_indentation ()
+      {
+        if (!hold_.empty () && hold_.back () == '\n')
+          for (UnsignedLong i (0); i < indentation_ * spaces_; ++i)
+            write (' ');
+      }
+
+      AsInt
+      write (AsChar c)
+      {
+        hold_.push_back (c);
+
+        AsInt result (Traits::eof ());
+
+        while (!hold_.empty ())
+        {
+          result = out_.put (hold_.front ());
+
+          if (result == Traits::eof ())
+            throw Write ();
+
+          hold_.pop_front ();
+        }
+
+        return result;
+      }
+
+
+    private:
+
+      Buffer<C>& out_;
+      UnsignedLong indentation_;
+      UnsignedLong spaces_;
+
+      Boolean suppress_nl_;
+
+      struct Construct
+      {
+        enum Value
+        {
+          other,
+          string_literal,
+          char_literal
+        };
+      };
+
+      //@@ gcc bug# 18304
+      //
+      typename Construct::Value construct_;
+
+      typedef
+      Cult::Containers::Deque<AsInt>
+      Hold;
+
+      Hold hold_;
+    };
+  }
+}
+
+#include <backend-elements/indentation/idl.txx>
+
+#endif  // BACKEND_ELEMENTS_INDENTATION_IDL_HXX
diff --git a/libbackend-elements/backend-elements/indentation/idl.txx b/libbackend-elements/backend-elements/indentation/idl.txx
new file mode 100644
index 0000000..6ddc63e
--- /dev/null
+++ b/libbackend-elements/backend-elements/indentation/idl.txx
@@ -0,0 +1,11 @@
+// file      : backend-elements/indentation/idl.txx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+namespace BackendElements
+{
+  namespace Indentation
+  {
+  }
+}
diff --git a/libbackend-elements/backend-elements/indentation/sloc.hxx b/libbackend-elements/backend-elements/indentation/sloc.hxx
new file mode 100644
index 0000000..57e6989
--- /dev/null
+++ b/libbackend-elements/backend-elements/indentation/sloc.hxx
@@ -0,0 +1,277 @@
+// file      : backend-elements/indentation/sloc.hxx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+#ifndef BACKEND_ELEMENTS_INDENTATION_SLOC_HXX
+#define BACKEND_ELEMENTS_INDENTATION_SLOC_HXX
+
+#include <backend-elements/types.hxx>
+#include <backend-elements/indentation/buffer.hxx>
+
+#include <cctype>
+#include <iostream> //@@ tmp
+
+namespace BackendElements
+{
+  namespace Indentation
+  {
+    template <typename C>
+    class SLOC: public Buffer<C>/*, public NonCopyable*/
+    {
+    public:
+      typedef
+      typename Buffer<C>::Traits
+      Traits;
+
+      typedef
+      typename Buffer<C>::AsChar
+      AsChar;
+
+      typedef
+      typename Buffer<C>::AsInt
+      AsInt;
+
+      typedef
+      typename Buffer<C>::Write
+      Write;
+
+    public:
+      SLOC (Buffer<C>& out)
+          : out_ (out),
+            count_ (0),
+            prev_ ('\0'),
+            code_counted_ (false),
+            construct_ (Construct::code)
+      {
+      }
+
+      UnsignedLong
+      count () const
+      {
+        return count_;
+      }
+
+    public:
+      virtual AsInt
+      put (AsChar c)
+      {
+        typename Construct::Value old (construct_);
+
+        switch (construct_)
+        {
+        case Construct::code:
+          {
+            code (c);
+            break;
+          }
+        case Construct::c_comment:
+          {
+            c_comment (c);
+            break;
+          }
+        case Construct::cxx_comment:
+          {
+            cxx_comment (c);
+            break;
+          }
+        case Construct::char_literal:
+          {
+            char_literal (c);
+            break;
+          }
+        case Construct::string_literal:
+          {
+            string_literal (c);
+            break;
+          }
+        }
+
+        // There are cases when a previous character has been already
+        // 'used' and therefore can not be used again. Good example
+        // would be '/* *//'. Here, the second slash doesn't start
+        // C++ comment since it was already used by C comment.
+        //
+        // To account for this we are going to set prev_ to '\0' when
+        // the mode changes.
+        //
+
+        prev_ = (old == construct_) ? c : '\0';
+
+        return out_.put (c);
+      }
+
+      virtual Void
+      unbuffer ()
+      {
+      }
+
+    private:
+      Void
+      code (AsChar c)
+      {
+        bool count (true);
+
+        switch (c)
+        {
+        case '/':
+          {
+            if (prev_ == '/')
+            {
+              construct_ = Construct::cxx_comment;
+              count = false;
+            }
+            else
+            {
+              // This slash can be a beginning of a comment but we
+              // yet have no way to know. Will have to examine it later
+              // (see below).
+              //
+              count = false;
+            }
+
+            break;
+          }
+        case '*':
+          {
+            if (prev_ == '/')
+            {
+              construct_ = Construct::c_comment;
+              count = false;
+            }
+            break;
+          }
+        case '\'':
+          {
+            construct_ = Construct::char_literal;
+            break;
+          }
+        case '"':
+          {
+            construct_ = Construct::string_literal;
+            break;
+          }
+        case '\n':
+          {
+            code_counted_ = false; // reset for a new line
+            count = false;
+            break;
+          }
+        default:
+          {
+            if (std::isspace (c))
+              count = false;
+            break;
+          }
+        }
+
+        // The second condition here accounts for the fact that we cannot
+        // count '/' right away since it can be a beginning of a comment.
+        //
+        if (!code_counted_ &&
+            (count || (prev_ == '/' && construct_ == Construct::code)))
+        {
+          //std::wcerr << "detected code @ " << c << std::endl;
+          count_++;
+          code_counted_ = true;
+        }
+      }
+
+      Void
+      c_comment (AsChar c)
+      {
+        switch (c)
+        {
+        case '/':
+          {
+            if (prev_ == '*')
+              construct_ = Construct::code;
+            break;
+          }
+        case '\n':
+          {
+            code_counted_ = false; // reset for a new line
+            break;
+          }
+        }
+      }
+
+      Void
+      cxx_comment (AsChar c)
+      {
+        switch (c)
+        {
+        case '\n':
+          {
+            construct_ = Construct::code;
+            code_counted_ = false; // reset for a new line
+            break;
+          }
+        }
+      }
+
+      Void
+      char_literal (AsChar c)
+      {
+        switch (c)
+        {
+        case '\'':
+          {
+            if (prev_ != '\\')
+              construct_ = Construct::code;
+            break;
+          }
+        }
+      }
+
+      Void
+      string_literal (AsChar c)
+      {
+        switch (c)
+        {
+        case '"':
+          {
+            if (prev_ != '\\')
+              construct_ = Construct::code;
+            break;
+          }
+        case '\n':
+          {
+            /*@@ Should I count multi-line string literal as multiple SLOC? */
+            break;
+          }
+        }
+      }
+
+    private:
+      Buffer<C>& out_;
+      UnsignedLong count_;
+
+      AsChar prev_; // previous character or '\0'
+
+      struct Construct
+      {
+        enum Value
+        {
+          code,
+          c_comment,
+          cxx_comment,
+          char_literal,
+          string_literal
+        };
+      };
+
+      // code
+      //
+      bool code_counted_;
+
+      //@@ gcc bug# 18304
+      //
+      typename Construct::Value construct_;
+    };
+  }
+}
+
+//#include <backend-elements/indentation/sloc.txx>
+
+#endif  // BACKEND_ELEMENTS_INDENTATION_SLOC_HXX
diff --git a/libbackend-elements/backend-elements/makefile b/libbackend-elements/backend-elements/makefile
new file mode 100644
index 0000000..70a3e4a
--- /dev/null
+++ b/libbackend-elements/backend-elements/makefile
@@ -0,0 +1,63 @@
+# file      : backend-elements/makefile
+# author    : Boris Kolpackov <boris@kolpackov.net>
+# copyright : Copyright (c) 2005-2010 Boris Kolpackov
+# license   : GNU GPL v2; see accompanying LICENSE file
+
+include $(dir $(lastword $(MAKEFILE_LIST)))../build/bootstrap.make
+
+cxx_tun   :=
+cxx_obj   := $(addprefix $(out_base)/,$(cxx_tun:.cxx=.o))
+cxx_od    := $(cxx_obj:.o=.o.d)
+
+backend_elements.l             := #$(out_base)/backend-elements.l
+backend_elements.l.cpp-options := $(out_base)/backend-elements.l.cpp-options
+
+clean     := $(out_base)/.clean
+
+
+# Secure default target.
+#
+$(backend_elements.l.cpp-options):
+#$(backend_elements.l):
+
+
+# Imports.
+#
+$(call import,\
+  $(scf_root)/import/libcult/stub.make,\
+  l: cult.l,cpp-options: cult.l.cpp-options)
+
+$(call import,\
+  $(scf_root)/import/libboost/regex/stub.make,\
+  l: re.l,cpp-options: re.l.cpp-options)
+
+
+# Build.
+#
+#$(backend_elements.l): $(cxx_obj) $(cult.l)
+
+#$(cxx_obj): $(backend_elements.l.cpp-options)
+
+$(backend_elements.l.cpp-options): value := -I$(src_root)
+$(backend_elements.l.cpp-options): $(re.l.cpp-options) $(cult.l.cpp-options)
+
+#$(call include-dep,$(cxx_od))
+
+
+# Convenience alias for default target.
+#
+$(out_base)/: $(backend_elements.l.cpp-options)
+
+
+# Clean.
+#
+#$(BackendElements.l).clean \
+
+$(clean): $(addsuffix .cxx.clean,$(cxx_obj)) \
+          $(backend_elements.l.cpp-options).clean
+
+
+# How to.
+#
+$(call include,$(bld_root)/cxx/o-l.make)
+$(call include,$(bld_root)/cxx/cxx-o.make)
diff --git a/libbackend-elements/backend-elements/regex.hxx b/libbackend-elements/backend-elements/regex.hxx
new file mode 100644
index 0000000..9dc6024
--- /dev/null
+++ b/libbackend-elements/backend-elements/regex.hxx
@@ -0,0 +1,208 @@
+// file      : backend-elements/regex.hxx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+#ifndef BACKEND_ELEMENTS_REGEX_HXX
+#define BACKEND_ELEMENTS_REGEX_HXX
+
+#include <ostream>
+
+#include <boost/regex.hpp>
+
+#include <backend-elements/types.hxx>
+
+namespace BackendElements
+{
+  namespace Regex
+  {
+    template <typename C>
+    struct Format
+    {
+      Format (StringTemplate<C> const& expression,
+              StringTemplate<C> const& description)
+          : expression_ (expression), description_ (description)
+      {
+      }
+
+      StringTemplate<C> const&
+      expression () const
+      {
+        return expression_;
+      }
+
+      StringTemplate<C> const&
+      description () const
+      {
+        return description_;
+      }
+
+    private:
+      StringTemplate<C> expression_;
+      StringTemplate<C> description_;
+    };
+
+    // Regex pattern.
+    //
+    template <typename C>
+    struct Pattern
+    {
+      Pattern ()
+      {
+      }
+
+      Pattern (Char const* p)
+      {
+        init (StringTemplate<C> (p));
+      }
+
+      Pattern (StringTemplate<C> const& p)
+      {
+        init (p);
+      }
+
+      Pattern&
+      operator= (Char const* p)
+      {
+        init (StringTemplate<C> (p));
+        return *this;
+      }
+
+      Pattern&
+      operator= (StringTemplate<C> const& p)
+      {
+        init (p);
+        return *this;
+      }
+
+    public:
+      Boolean
+      match (StringTemplate<C> const& s) const
+      {
+        return regex_match (s, pat_, boost::format_all);
+      }
+
+      StringTemplate<C>
+      merge (StringTemplate<C> const& sub,
+             StringTemplate<C> const& s,
+             Boolean first_only = false) const
+      {
+        if (first_only)
+          return regex_merge (
+            s, pat_, sub, boost::format_all | boost::format_first_only);
+        else
+          return regex_merge ( s, pat_, sub, boost::format_all);
+      }
+
+    public:
+      Boolean
+      empty () const
+      {
+        return pat_.empty ();
+      }
+
+    public:
+      boost::basic_regex<C> const&
+      impl_pattern () const
+      {
+        return pat_;
+      }
+
+    private:
+      Void
+      init (StringTemplate<C> const& r);
+
+    private:
+      boost::basic_regex<C> pat_;
+    };
+
+    template <typename C1, typename C2>
+    inline std::basic_ostream<C1>&
+    operator<< (std::basic_ostream<C1>& os, Pattern<C2> const& p)
+    {
+      return os << p.impl_pattern ().str ().c_str ();
+    }
+
+    // Regex expression: '/pattern/substitution/'.
+    //
+    template <typename C>
+    struct Expression
+    {
+      Expression ()
+      {
+      }
+
+      // Expression is of the form /regex/format/ where '/' can be
+      // replaced with any delimiter.
+      //
+      Expression (Char const* e)
+      {
+        init (StringTemplate<C> (e));
+      }
+
+      Expression (StringTemplate<C> const& e)
+      {
+        init (e);
+      }
+
+      Expression&
+      operator= (Char const* e)
+      {
+        init (StringTemplate<C> (e));
+        return *this;
+      }
+
+      Expression&
+      operator= (StringTemplate<C> const& e)
+      {
+        init (e);
+        return *this;
+      }
+
+    public:
+      Boolean
+      match (StringTemplate<C> const& s) const
+      {
+        return pat_.match (s);
+      }
+
+      StringTemplate<C>
+      merge (StringTemplate<C> const& s, Boolean first_only = false) const
+      {
+        return pat_.merge (sub_, s, first_only);
+      }
+
+    public:
+      const Pattern<C>&
+      pattern () const
+      {
+        return pat_;
+      }
+
+      const StringTemplate<C>&
+      substitution () const
+      {
+        return sub_;
+      }
+
+    public:
+      Boolean
+      empty () const
+      {
+        return pat_.empty () && sub_.empty ();
+      }
+
+    private:
+      Void
+      init (StringTemplate<C> const& r);
+
+    private:
+      Pattern<C> pat_;
+      StringTemplate<C> sub_;
+    };
+  }
+}
+
+#include <backend-elements/regex.txx>
+
+#endif  // BACKEND_ELEMENTS_REGEX_HXX
diff --git a/libbackend-elements/backend-elements/regex.txx b/libbackend-elements/backend-elements/regex.txx
new file mode 100644
index 0000000..897e0e8
--- /dev/null
+++ b/libbackend-elements/backend-elements/regex.txx
@@ -0,0 +1,52 @@
+// file      : backend-elements/regex.txx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+namespace BackendElements
+{
+  namespace Regex
+  {
+    template <typename C>
+    Void Pattern<C>::
+    init (StringTemplate<C> const& r)
+    {
+      try
+      {
+        pat_ = r;
+      }
+      catch (boost::regex_error const& e)
+      {
+        throw Format<C> (r, e.what ());
+      }
+    }
+
+    //
+    //
+    template <typename C>
+    Void Expression<C>::
+    init (StringTemplate<C> const& r)
+    {
+      typedef StringTemplate<C> String;
+
+      if (r.empty ())
+        throw Format<C> (r, "empty expression");
+
+      C d (r[0]);
+
+      Size first (0);
+      Size middle (r.find (d, first + 1));
+
+      if (middle == String::npos)
+        throw Format<C> (r, "missing second pattern-substitution separator");
+
+      Size last (r.find (d, middle + 1));
+
+      if (last == String::npos)
+        throw Format<C> (r, "missing third pattern-substitution separator");
+
+      pat_ = String (r, first + 1, middle - first - 1);
+      sub_.assign (r, middle + 1, last - middle - 1);
+    }
+  }
+}
diff --git a/libbackend-elements/backend-elements/types.hxx b/libbackend-elements/backend-elements/types.hxx
new file mode 100644
index 0000000..f309f5d
--- /dev/null
+++ b/libbackend-elements/backend-elements/types.hxx
@@ -0,0 +1,16 @@
+// file      : backend-elements/types.hxx
+// author    : Boris Kolpackov <boris@kolpackov.net>
+// copyright : Copyright (c) 2005-2010 Boris Kolpackov
+// license   : GNU GPL v2 + exceptions; see accompanying LICENSE file
+
+#ifndef BACKEND_ELEMENTS_TYPES_HXX
+#define BACKEND_ELEMENTS_TYPES_HXX
+
+#include <cult/types.hxx>
+
+namespace BackendElements
+{
+  using namespace Cult::Types;
+}
+
+#endif  // BACKEND_ELEMENTS_TYPES_HXX