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/*
** SWISH++
** token.c
**
** 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.
*/
// standard
#include <cctype>
#include <cstring>
#include <iostream.h>
// local
#include "config.h"
#include "fake_ansi.h"
#include "token.h"
#include "util.h"
#ifndef PJL_NO_NAMESPACES
using namespace std;
#endif
bool token::on_hold_;
//
// We needed somplace to store a token that was put back but obviously can't
// declare a token static data member inside token directly.
//
token& token::hold() {
static token t;
return t;
}
//*****************************************************************************
//
// SNYOPSIS
//
istream& operator>>( istream &in, token &t )
//
// DESCRIPTION
//
// Extract a token from the given input stream.
//
// PARAMETERS
//
// in The input stream to extract the token from.
//
// t The newly extracted token.
//
// RETURN VALUE
//
// Returns the given input stream as is standard practice.
//
// SEE ALSO
//
// Stroustrup, Bjarne. "The C++ Programming Language, 3rd ed."
// Addison-Wesley, Reading, MA. p. 621.
//
//*****************************************************************************
{
if ( token::on_hold_ ) {
//
// If there was a token previously put back, use it.
//
t = token::hold();
token::on_hold_ = false;
return in;
}
t.type_ = token::no_token;
bool in_word = false;
char c;
while ( in.get( c ) ) {
if ( is_word_char( c ) ) {
if ( !in_word ) {
// start a new word
t.buf_[ 0 ] = tolower( c );
t.len_ = 1;
in_word = true;
continue;
}
if ( t.len_ < Word_Hard_Max_Size ) {
// continue same word
t.buf_[ t.len_++ ] = tolower( c );
continue;
}
in_word = false; // too big: skip chars
while ( in.get( c ) && is_word_char( c ) ) ;
continue;
}
if ( in_word ) {
if ( c == '*' )
t.type_ = token::word_star_token;
else
in.putback( c );
break;
}
switch ( c ) {
case '(':
t.type_ = token::lparen_token;
return in;
case ')':
t.type_ = token::rparen_token;
return in;
}
}
if ( in_word ) {
t.buf_[ t.len_ ] = '\0';
if ( t.type_ )
return in;
//
// Check to see if the word is an operator. For only 3
// comparisons, linear search is good enough.
//
if ( !::strcmp( t.buf_, "and" ) )
t.type_ = token::and_token;
else if ( !::strcmp( t.buf_, "or" ) )
t.type_ = token::or_token;
else if ( !::strcmp( t.buf_, "not" ) )
t.type_ = token::not_token;
else
t.type_ = token::word_token;
}
return in;
}
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