Parsing XML in C++ using the YARD Parser

// released into the public domain 
// by Christopher Diggins 2004 
// http://www.cdiggins.com 

#ifndef RULES_HPP_INCLUDED 
#define RULES_HPP_INCLUDED  

#include "re_ops.hpp"

namespace yard 
{
  template<char C>
  struct MatchChar
  {
    static bool Accept(ParserInputStream<char>& stream) {
      return (stream.AdvancePast(C));
    }
  };

  template<char C0, char C1>
  struct MatchCharRange
  {
    static bool Accept(ParserInputStream<char>& stream) {
      char ch = stream.GetElem();
      if ((ch >= C0) && (ch <= C1)) {
        stream.GotoNext();         
        return true;
      }
      return false;
    }
  };
  
  template<typename String_T>
  struct MatchString 
  {  
    static bool Accept(ParserInputStream<char>& stream) {      
      char const* p = String_T::GetString();
      for (int i = 0; p[i] != NULL; ++i) { 
        if (stream.AtEnd()) return false;
        char ch = stream.GetElem();
        stream.GotoNext();        
        if (ch != p[i]) return false;
      }
      return true;
    }
  };
 
  template<typename String_T> // expected to be lower-case 
  struct MatchStringNoCase 
  {  
    static bool Accept(ParserInputStream<char>& stream) {      
      char const* p = String_T::GetString();
      for (int i = 0; p[i] != NULL; ++i) { 
        if (stream.AtEnd()) return false;
        char ch = stream.GetElem();
        stream.GotoNext();                
        if (ch < 96) ch += 32; 
        if (ch != p[i]) return false;
      }
      return true;
    }
  };
  
  struct MatchWSpace : public 
    re_or<
      re_or<
        MatchChar<' '>, 
        MatchChar<'\t'> 
      >, 
      re_or<
        MatchChar<'\n'>, 
        MatchChar<'\r'> 
      > 
    >
    { };

  typedef MatchCharRange<'a', 'z'> MatchLowerCaseLetter;
  typedef MatchCharRange<'A', 'Z'> MatchUpperCaseLetter; 
  typedef MatchCharRange<'0', '9'> MatchNumber;
  
  typedef re_or<MatchLowerCaseLetter, MatchUpperCaseLetter> MatchLetter;
  typedef re_or<MatchLetter, MatchChar<'\''> > MatchWordChar;
  typedef re_plus<MatchWordChar> MatchWord;
  typedef re_or<MatchLetter, MatchChar<'_'> > MatchIdentFirstChar;
  typedef re_or<MatchIdentFirstChar, MatchNumber> MatchIdentOtherChar;
  typedef re_and<MatchIdentFirstChar, re_star<MatchIdentOtherChar> > MatchIdent;
}

#endif // #ifndef RULES_HPP_INCLUDED