[Cpptool-cvs] rfta/include/xtl MiniParser.h,NONE,1.1

[<bl...@us...>]

Update of /cvsroot/cpptool/rfta/include/xtl
In directory sc8-pr-cvs1:/tmp/cvs-serv31091/include/xtl

Added Files:
	MiniParser.h 
Log Message:
* experimenting with implementation of a simplistic parser framework (akin to Boost.Spirit, but much more simple). Still need to devise how matched parts are returned...

--- NEW FILE: MiniParser.h ---
#ifndef XTL_MINIPARSER_H_INCLUDED
#define XTL_MINIPARSER_H_INCLUDED

#include <xtl/CStringView.h>
#include <stdexcept>

namespace Xtl {

template<typename LeftParserType
        ,typename RightParserType>
class SequenceMiniParser;

template<typename ParserType>
class OptionalMiniParser;

template<typename LeftParserType
        ,typename RightParserType>
class AlternativeMiniParser;


class Scanner
{
public:
   typedef const char *Iterator;

   explicit Scanner( const Xtl::CStringView &content )
      : start_( content.getStart() )
      , end_( content.getEnd() )
      , current_( start_ )
   {
   }

   Scanner( const char *first, 
            const char *last )
      : start_( first )
      , end_( last )
      , current_( start_ )
   {
   }

   bool hasNext() const
   {
      return current_ != end_;
   }

   bool isAtEnd() const
   {
      return current_ == end_;
   }

   char operator *() const
   {
#ifndef NDEBUG
      if ( isAtEnd() )
         throw std::logic_error( "Scanner::operator *() called at end of content." );
#endif
      return *current_;
   }
   
   Scanner &operator ++()
   {
#ifndef NDEBUG
      if ( isAtEnd() )
         throw std::logic_error( "Scanner::operator ++() called at end of content." );
#endif
      ++current_;
      return *this;
   }

   Scanner::Iterator current() const
   {
      return current_;
   }

   void backtrack( Scanner::Iterator rollback )
   {
      current_ = rollback;
   }

private:
   const Iterator start_;
   const Iterator end_;
   Iterator current_;
};




struct ParseResult
{
   ParseResult()
      : matched_( false )
   {
   }

   ParseResult( Scanner::Iterator start, Scanner::Iterator end )
      : matched_( true )
      , matchStart_( start )
      , matchEnd_( end )
   {
   }

   bool matched_;
   Scanner::Iterator matchStart_;
   Scanner::Iterator matchEnd_;
};


struct MandatoryMiniParserCategory
{
   enum { isOptional = false };
};


struct OptionalMiniParserCategory
{
   enum { isOptional = true };
};


class MiniParser
{
public:
   typedef MandatoryMiniParserCategory Category;

   virtual ParseResult parse( Scanner &scanner ) const = 0;

   ParseResult noMatch() const
   {
      return ParseResult();
   }

   ParseResult matched( Scanner::Iterator start,
                        const Scanner &scanner ) const
   {
      return ParseResult( start, scanner.current() );
   }

   ParseResult concatResult( const ParseResult &left, const ParseResult &right ) const
   {
      return ParseResult( left.matchStart_, right.matchEnd_ );
   }

   ParseResult emptyMatch( Scanner::Iterator start ) const
   {
      return ParseResult( start, start );
   }
};


template<typename DerivedParserType>
class MiniParserBase : public MiniParser
{
public:
   template<typename RightParserType>
   SequenceMiniParser<DerivedParserType,RightParserType> 
      operator >>( const RightParserType &parser) const
   {
      return makeSequenceParser( static_cast<const DerivedParserType &>(*this), parser );
   }


   template<typename RightParserType>
   AlternativeMiniParser<DerivedParserType,RightParserType> 
      operator |( const RightParserType &parser) const
   {
      return makeAlternativeParser( static_cast<const DerivedParserType &>(*this), parser );
   }


   OptionalMiniParser<DerivedParserType> operator !() const
   {
      return makeOptionalParser( static_cast<const DerivedParserType &>(*this) );
   }
};



class CharMiniParser : public MiniParserBase<CharMiniParser>
{
public:
   CharMiniParser( char ch )
      : ch_( ch )
   {
   }

   ParseResult parse( Scanner &scanner ) const
   {
      if ( scanner.hasNext() )
      {
         if ( *scanner == ch_ )
         {
            Scanner::Iterator start = scanner.current();
            ++scanner;
            return matched( start, scanner );
         }
      }

      return noMatch();
   }

private:
   char ch_;
};


class StringMiniParser : public MiniParserBase<StringMiniParser>
{
public:
   StringMiniParser( const std::string &text )
      : text_( text )
      , first_( text_.c_str() )
      , last_( text_.c_str() + text_.length() )
   {
   }

   ParseResult parse( Scanner &scanner ) const
   {
      Scanner::Iterator start = scanner.current();
      const char *str = first_;
      while ( str != last_ )
      {
         if ( scanner.isAtEnd()  ||  *scanner != *str )
            return noMatch();
         ++str;
         ++scanner;
      }

      return matched( start, scanner );
   }

private:
   std::string text_;
   const char *first_;
   const char *last_;
};


struct CppIdentifierTraits
{
   inline static bool isIdentifierFirstLetter( char letter )
   {
      return (letter >= 'a'  &&  letter <= 'z' )  ||
             (letter >= 'A'  &&  letter <= 'Z' )  ||
             letter == '_';
   }

   inline static bool isIdentifierLetter( char letter )
   {
      return (letter >= 'a'  &&  letter <= 'z' )  ||
             (letter >= 'A'  &&  letter <= 'Z' )  ||
             (letter >= '0'  &&  letter <= '9' )  ||
             letter == '_';
   }
};


struct MacroIdentifierTraits
{
   inline static bool isIdentifierFirstLetter( char letter )
   {
      return (letter >= 'A'  &&  letter <= 'Z' )  ||
             letter == '_';
   }

   inline static bool isIdentifierLetter( char letter )
   {
      return (letter >= 'A'  &&  letter <= 'Z' )  ||
             (letter >= '0'  &&  letter <= '9' )  ||
             letter == '_';
   }
};


template<typename IdentifierTraits>
class IdentifierMiniParser : public MiniParserBase< IdentifierMiniParser<IdentifierTraits> >
{
public:
   ParseResult parse( Scanner &scanner ) const
   {
      Scanner::Iterator start = scanner.current();
      if ( scanner.hasNext()  &&  IdentifierTraits::isIdentifierFirstLetter( *scanner ) )
      {
         ++scanner;
         while ( scanner.hasNext()  &&  IdentifierTraits::isIdentifierLetter( *scanner ) )
            ++scanner;
         return matched( start, scanner );
      }

      return noMatch();
   }
};


typedef IdentifierMiniParser<CppIdentifierTraits> CppIdentifierMiniParser;
typedef IdentifierMiniParser<MacroIdentifierTraits> MacroIdentifierMiniParser;


template<typename ParserType
        ,typename DerivedParserType>
class UnaryMiniParser : public MiniParserBase<DerivedParserType>
{
public:
   typedef ParserType Parser;

   UnaryMiniParser( const Parser &parser )
      : parser_( parser )
   {
   }

protected:
   Parser parser_;
};


template<typename LeftParserType
        ,typename RightParserType
        ,typename DerivedParserType>
class BinaryMiniParser : public MiniParserBase<DerivedParserType>
{
public:
   typedef LeftParserType LeftParser;
   typedef RightParserType RightParser;

   BinaryMiniParser( const LeftParser &left,
                     const RightParser &right )
      : leftParser_( left )
      , rightParser_( right )
   {
   }

protected:
   LeftParser leftParser_;
   RightParser rightParser_;
};


template<typename LeftParserType
        ,typename RightParserType>
class SequenceMiniParser : public BinaryMiniParser<LeftParserType
                                                  ,RightParserType
                                                  ,SequenceMiniParser<LeftParserType
                                                                     ,RightParserType> >
{
public:
   typedef BinaryMiniParser<LeftParserType
                           ,RightParserType
                           ,SequenceMiniParser<LeftParserType
                                              ,RightParserType> > SuperClass;

   SequenceMiniParser( const LeftParser &left,
                       const RightParser &right )
      : SuperClass( left, right )
   {
   }

   ParseResult parse( Scanner &scanner ) const
   {
      ParseResult leftResult = leftParser_.parse( scanner );
      if ( leftResult.matched_ )
      {
         ParseResult rightResult = rightParser_.parse( scanner );
         if ( rightResult.matched_ )
            return concatResult( leftResult, rightResult );
      }

      return noMatch();
   }
};


template<typename LeftParserType
        ,typename RightParserType>
SequenceMiniParser<LeftParserType,RightParserType> 
makeSequenceParser( const LeftParserType &left,
                    const RightParserType &right )
{
   return SequenceMiniParser<LeftParserType,RightParserType>( left, right );
}



template<typename ParserType>
class OptionalMiniParser : public UnaryMiniParser<ParserType
                                                 ,OptionalMiniParser<ParserType> >
{
public:
   typedef UnaryMiniParser<ParserType,OptionalMiniParser<ParserType> > SuperClass;

   typedef OptionalMiniParserCategory Category;

   OptionalMiniParser( const ParserType &parser )
      : SuperClass( parser )
   {
   }

   ParseResult parse( Scanner &scanner ) const
   {
      Scanner::Iterator rollback = scanner.current();

      ParseResult result = parser_.parse( scanner );
      if ( result.matched_ )
         return result;

      scanner.backtrack( rollback );
      return emptyMatch( rollback );
   }
};


template<typename ParserType>
OptionalMiniParser<ParserType> makeOptionalParser( const ParserType &parser )
{
   return OptionalMiniParser<ParserType>( parser );
}




template<typename LeftParserType
        ,typename RightParserType>
class AlternativeMiniParser : public BinaryMiniParser<LeftParserType
                                                     ,RightParserType
                                                     ,AlternativeMiniParser<LeftParserType
                                                                           ,RightParserType> >
{                                                         
public:
   typedef BinaryMiniParser<LeftParserType
                           ,RightParserType
                           ,AlternativeMiniParser<LeftParserType
                                                 ,RightParserType> > SuperClass;

   AlternativeMiniParser( const LeftParser &left,
                       const RightParser &right )
      : SuperClass( left, right )
   {
   }

   ParseResult parse( Scanner &scanner ) const
   {
      Scanner::Iterator initial = scanner.current();
      ParseResult leftResult = leftParser_.parse( scanner );
      if ( leftResult.matched_ )
         return leftResult;

      scanner.backtrack( initial );
      return rightParser_.parse( scanner );
   }
};


template<typename LeftParserType
        ,typename RightParserType>
AlternativeMiniParser<LeftParserType,RightParserType> 
makeAlternativeParser( const LeftParserType &left,
                       const RightParserType &right )
{
   return AlternativeMiniParser<LeftParserType,RightParserType>( left, right );
}



} // namespace Xtl

#endif // XTL_MINIPARSER_H_INCLUDED