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examples: lexcalc: demonstrate location tracking

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The bistromathic example should not use Flex, it makes it too complex.
But it was the only example to show location tracking with Flex.

* examples/c/lexcalc/lexcalc.test, examples/c/lexcalc/parse.y,
* examples/c/lexcalc/scan.l: Demonstrate location tracking as is done
in bistromathic.
This commit is contained in:
Akim Demaille
2020-02-29 09:54:34 +01:00
parent b870d5fee4
commit 388e12ac0f
8 changed files with 46 additions and 16 deletions
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25
examples/c/lexcalc/scan.l
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@@ -9,9 +9,24 @@
#include <stdlib.h> /* strtol */
#include "parse.h"
// Each time a rule is matched, advance the end cursor/position.
#define YY_USER_ACTION \
yylloc->last_column += yyleng;
// Move the first position onto the last.
#define LOCATION_STEP() \
do { \
yylloc->first_line = yylloc->last_line; \
yylloc->first_column = yylloc->last_column; \
} while (0)
%}
%%
%{
// Each time yylex is called, move the head position to the end one.
LOCATION_STEP ();
%}
/* Rules. */
"+" return TOK_PLUS;
@@ -27,17 +42,17 @@
errno = 0;
long n = strtol (yytext, NULL, 10);
if (! (INT_MIN <= n && n <= INT_MAX && errno != ERANGE))
yyerror (nerrs, "integer is out of range");
yyerror (yylloc, nerrs, "integer is out of range");
yylval->TOK_NUM = (int) n;
return TOK_NUM;
}
"\n" yylloc->last_line++; yylloc->last_column = 1; return TOK_EOL;
/* Ignore white spaces. */
[ \t]+ continue;
[ \t]+ LOCATION_STEP (); continue;
"\n" return TOK_EOL;
. yyerror (nerrs, "syntax error, invalid character");
. yyerror (yylloc, nerrs, "syntax error, invalid character"); continue;
<<EOF>> return TOK_EOF;
%%