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/* Prologue (directives). -*- C -*- */
/* Disable Flex features we don't need, to avoid warnings. */
%option nodefault noinput nounput noyywrap
%option reentrant
%{
#include <assert.h>
#include <limits.h> /* INT_MIN */
#include <stdlib.h> /* strtol */
#include "parse.h"
%}
%x SC_STRING
%%
%{
// Number of opened parentheses.
int nesting = 0;
// A buffer storing the text inside the outer parentheses.
char *str = NULL;
// Its allocated size.
int capacity = 0;
// Its used size.
int size = 0;
#define STR_APPEND() \
do { \
if (capacity < size + yyleng + 1) \
{ \
do \
capacity = capacity ? 2 * capacity : 128; \
while (capacity < size + yyleng + 1); \
str = realloc (str, capacity); \
} \
memcpy (str + size, yytext, yyleng); \
size += yyleng; \
assert (size < capacity); \
} while (0)
%}
// Rules.
"+" return TOK_PLUS;
"-" return TOK_MINUS;
"*" return TOK_STAR;
"/" return TOK_SLASH;
"(" nesting += 1; BEGIN SC_STRING;
/* Scan an integer. */
[0-9]+ {
errno = 0;
long n = strtol (yytext, NULL, 10);
if (! (INT_MIN <= n && n <= INT_MAX && errno != ERANGE))
yyerror (yyscanner, res, "integer is out of range");
yylval->TOK_NUM = (int) n;
return TOK_NUM;
}
/* Ignore white spaces. */
[ \t]+ continue;
"\n" return TOK_EOL;
. yyerror (yyscanner, res, "syntax error, invalid character: %c", yytext[0]);
<SC_STRING>
{
"("+ nesting += yyleng; STR_APPEND ();
")" {
if (!--nesting)
{
BEGIN INITIAL;
if (str)
str[size] = 0;
yylval->TOK_STR = str;
return TOK_STR;
}
else
STR_APPEND ();
}
[^()]+ STR_APPEND ();
}
<<EOF>> return TOK_EOF;
%%
/* Epilogue (C code). */
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