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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.
60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
/* Prologue (directives). -*- C -*- */
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/* Disable Flex features we don't need, to avoid warnings. */
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%option nodefault noinput nounput noyywrap
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%{
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#include <errno.h> /* errno, ERANGE */
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#include <limits.h> /* INT_MIN */
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#include <stdlib.h> /* strtol */
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#include "parse.h"
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// Each time a rule is matched, advance the end cursor/position.
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#define YY_USER_ACTION \
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yylloc->last_column += yyleng;
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// Move the first position onto the last.
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#define LOCATION_STEP() \
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do { \
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yylloc->first_line = yylloc->last_line; \
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yylloc->first_column = yylloc->last_column; \
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} while (0)
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%}
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%%
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%{
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// Each time yylex is called, move the head position to the end one.
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LOCATION_STEP ();
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%}
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/* Rules. */
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"+" return TOK_PLUS;
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"-" return TOK_MINUS;
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"*" return TOK_STAR;
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"/" return TOK_SLASH;
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"(" return TOK_LPAREN;
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")" return TOK_RPAREN;
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/* Scan an integer. */
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[0-9]+ {
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errno = 0;
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long n = strtol (yytext, NULL, 10);
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if (! (INT_MIN <= n && n <= INT_MAX && errno != ERANGE))
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yyerror (yylloc, nerrs, "integer is out of range");
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yylval->TOK_NUM = (int) n;
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return TOK_NUM;
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}
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"\n" yylloc->last_line++; yylloc->last_column = 1; return TOK_EOL;
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/* Ignore white spaces. */
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[ \t]+ LOCATION_STEP (); continue;
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. yyerror (yylloc, nerrs, "syntax error, invalid character"); continue;
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<<EOF>> return TOK_EOF;
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%%
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/* Epilogue (C code). */
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