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/*
** SWISH++
** token.h
**
** Copyright (C) 1998 Paul J. Lucas
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef token_H
#define token_H
// local
#include "config.h"
#include "fake_ansi.h" /* for explicit, std */
#include "platform.h"
// standard
#ifdef PJL_GCC_2xx
#include <strstream>
#else
#include <sstream>
#endif
class token_stream;
//*****************************************************************************
//
// SYNOPSIS
//
class token
//
// DESCRIPTION
//
// This class is used to contain a token parsed from a token_stream.
//
//*****************************************************************************
{
public:
enum type {
no_token,
word_token,
word_star_token,
and_token,
or_token,
not_token,
lparen_token,
rparen_token,
equal_token
};
token() : type_( no_token ) { }
explicit token( token_stream &in ) { in >> *this; }
operator type() const { return type_; }
int length() const { return len_; }
char const* str() const { return buf_; }
char const* lower_str() const { return lower_buf_; }
friend token_stream& operator>>( token_stream&, token& );
private:
type type_;
char buf_[ Word_Hard_Max_Size + 1 ];
char lower_buf_[ Word_Hard_Max_Size + 1 ];
int len_;
};
//*****************************************************************************
//
// SYNOPSIS
//
#ifdef PJL_GCC_2xx
class token_stream : public std::istrstream
#else
class token_stream : public std::istringstream
#endif
//
// DESCRIPTION
//
// A token_stream is-an istrstream that has the additional ability to put
// back previously parsed tokens used as look-ahead. Note that it puts
// back whole, already-parsed tokens rather than characters so they don't
// have to be parsed again.
//
//*****************************************************************************
{
public:
#ifdef PJL_GCC_2xx
token_stream( char const *s ) : std::istrstream( s ), top_( -1 ) { }
#else
token_stream( char const *s ) : std::istringstream( s ), top_( -1 ) { }
#endif
void put_back( token const &t ) { stack_[ ++top_ ] = t; }
private:
// Our query parser needs at most 2 look-ahead tokens.
token stack_[ 2 ];
int top_;
token* put_back() { return top_ >= 0 ? stack_ + top_-- : 0; }
friend token_stream& operator>>( token_stream&, token& );
};
#endif /* token_H */
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