Lexer: Added ::decomposeSubstitution and more flexible ::dequote

- ::dequote can now be given a string of valid quote characters, which defaults
  to '".
- ::decomposeSubstitution properly parses the /from/to/g construct allowing for
  escaped characters (\/).
- The 'g' at the end of a substitution is now considered to be a string of flag
  characters, which may contain 'g'. No other flag values are currently
  supported.

src/Lexer.cpp

@@ -324,14 +324,14 @@ bool Lexer::isPunctuation (int c)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-void Lexer::dequote (std::string& input)
+void Lexer::dequote (std::string& input, const std::string& quotes)
 {
   int quote = input[0];
-  size_t len = input.length ();
+  if (quotes.find (quote) != std::string::npos)
-  if ((quote == '\'' || quote == '"') &&
-      quote == input[len - 1])
   {
-    input = input.substr (1, len - 2);
+    size_t len = input.length ();
+    if (input[0] == input[len - 1])
+      input = input.substr (1, len - 2);
   }
 }
 
@@ -1403,3 +1403,37 @@ bool Lexer::decomposePair (
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+// / <from> / <to> / [<flags>]
+bool Lexer::decomposeSubstitution (
+  const std::string& text,
+  std::string& from,
+  std::string& to,
+  std::string& flags)
+{
+  std::string parsed_from;
+  std::string::size_type cursor = 0;
+  if (readWord (text, "/", cursor, parsed_from) &&
+      parsed_from.length ())
+  {
+    --cursor;
+    std::string parsed_to;
+    if (readWord (text, "/", cursor, parsed_to))
+    {
+      std::string parsed_flags = text.substr (cursor);
+      if (parsed_flags.find ("/") == std::string::npos)
+      {
+        dequote (parsed_from, "/");
+        dequote (parsed_to,   "/");
+
+        from  = parsed_from;
+        to    = parsed_to;
+        flags = parsed_flags;
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+////////////////////////////////////////////////////////////////////////////////

src/Lexer.h

@@ -74,11 +74,12 @@ public:
   static bool isPunctuation         (int);
   static bool isAllDigits           (const std::string&);
   static bool isOneWord             (const std::string&);
-  static void dequote               (std::string&);
+  static void dequote               (std::string&, const std::string& quotes = "'\"");
   static bool wasQuoted             (const std::string&);
   static bool readWord              (const std::string&, const std::string&, std::string::size_type&, std::string&);
   static bool readWord              (const std::string&, std::string::size_type&, std::string&);
   static bool decomposePair         (const std::string&, std::string&, std::string&, std::string&, std::string&);
+  static bool decomposeSubstitution (const std::string&, std::string&, std::string&, std::string&);
   static int hexToInt               (int);
   static int hexToInt               (int, int);
   static int hexToInt               (int, int, int, int);