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/*
* fhist - file history and comparison tools
* Copyright (C) 1998, 2002, 2008 Peter Miller
*
* 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 3 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, see
* <http://www.gnu.org/licenses/>.
*/
#include <str.h>
#include <sub/expr_lex.h>
#include <sub/expr_gram.gen.h>
static string_ty *text;
static size_t pos;
void
sub_expr_lex_open(string_ty *s)
{
text = s;
pos = 0;
}
void
sub_expr_lex_close(void)
{
text = 0;
pos = 0;
}
static int
lex_getc(void)
{
int c;
if (!text || pos >= text->str_length)
c = 0;
else
c = (unsigned char)text->str_text[pos];
++pos;
return c;
}
static void
lex_getc_undo(int c)
{
if (pos > 0)
--pos;
}
int
sub_expr_gram_lex(void)
{
int c;
long n;
for (;;)
{
c = lex_getc();
switch (c)
{
case 0:
return 0;
case '(':
return LP;
case ')':
return RP;
case '-':
return MINUS;
case '+':
return PLUS;
case '*':
return MUL;
case '/':
return DIV;
case ' ':
case '\t':
case '\n':
case '\f':
break;
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
n = 0;
for (;;)
{
n = n * 10 + c - '0';
c = lex_getc();
switch (c)
{
case '0': case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
case '8': case '9':
continue;
default:
break;
}
lex_getc_undo(c);
break;
}
sub_expr_gram_lval.lv_number = n;
return NUMBER;
default:
return JUNK;
}
}
}
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