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Token.h
//
// Token.h
//
// $Id: //poco/1.4/Foundation/include/Poco/Token.h#1 $
//
// Library: Foundation
// Package: Streams
// Module:  StreamTokenizer
//
// Definition of the Token class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_Token_INCLUDED
#define Foundation_Token_INCLUDED


#include "Poco/Foundation.h"
#include <istream>


namespace Poco {


00050 class Foundation_API Token
      /// The base class for all token classes that can be
      /// registered with the StreamTokenizer.
{
public:
      enum Class
      {
            IDENTIFIER_TOKEN,
            KEYWORD_TOKEN,
            SEPARATOR_TOKEN,
            OPERATOR_TOKEN,
            STRING_LITERAL_TOKEN,
            CHAR_LITERAL_TOKEN,
            INTEGER_LITERAL_TOKEN,
            LONG_INTEGER_LITERAL_TOKEN,
            FLOAT_LITERAL_TOKEN,
            DOUBLE_LITERAL_TOKEN,
            COMMENT_TOKEN,
            SPECIAL_COMMENT_TOKEN,
            PREPROCESSOR_TOKEN,
            WHITESPACE_TOKEN,
            EOF_TOKEN,
            INVALID_TOKEN,
            USER_TOKEN
      };
      
      Token();
            /// Creates the Token.

      virtual ~Token();
            /// Destroys the Token.
            
      virtual bool start(char c, std::istream& istr);
            /// Checks if the given character (and, optionally,
            /// the next character in the input stream) start
            /// a valid token. Returns true if so, false
            /// otherwise.
            ///
            /// The current read position in istr must not be
            /// changed. In other words, only the peek() method
            /// of istream may be used.
            ///
            /// If the character starts the token, it should
            /// be set as the token's value.

      virtual void finish(std::istream& istr);
            /// Builds the token by reading and appending 
            /// the remaining characters from istr.
            
      virtual Class tokenClass() const;
            /// Returns the kind of the token.
      
      const std::string& tokenString() const;
            /// Returns the token's raw string.
      
      virtual std::string asString() const;
            /// Returns a string representation of the token.
      
      virtual int asInteger() const;
            /// Returns an integer representation of the token.
      
      virtual double asFloat() const;
            /// Returns a floating-point representation of the token.

      virtual char asChar() const;
            /// Returns a char representation of the token.

      bool is(Class tokenClass) const;
            /// Returns true iff the token has the given class.

protected:
00121       std::string _value;
      
private:
      Token(const Token&);
      Token& operator = (const Token&);
};


00129 class Foundation_API InvalidToken: public Token
      /// This token class is used for signalling that
      /// an invalid character sequence has been encountered
      /// in the input stream.
{
public:
      InvalidToken();
      ~InvalidToken();
      Class tokenClass() const;
};


00141 class Foundation_API EOFToken: public Token
      /// This token class is used to signal the
      /// end of the input stream.
{
public:
      EOFToken();
      ~EOFToken();
      Class tokenClass() const;
};


00152 class Foundation_API WhitespaceToken: public Token
      /// This pseudo token class is used to eat
      /// up whitespace in between real tokens.
{
public:
      WhitespaceToken();
      ~WhitespaceToken();
      Class tokenClass() const;
      bool start(char c, std::istream& istr);
      void finish(std::istream& istr);
};


//
// inlines
//
00168 inline const std::string& Token::tokenString() const
{
      return _value;
}


00174 inline bool Token::is(Token::Class cls) const
{
      return tokenClass() == cls;
}


} // namespace Poco


#endif // Foundation_Token_INCLUDED

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