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examples: don't demonstrate multistart, which is not part of 3.8

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Besides, for mysterious reasons, this fails on some environment.
Reported by Dagobert Michelsen.
<https://lists.gnu.org/archive/html/bug-bison/2021-08/msg00008.html>

* examples/c/lexcalc/lexcalc.test, examples/c/lexcalc/parse.y,
* examples/c/lexcalc/scan.l: Revert to a single-start example.
This commit is contained in:
Akim Demaille
2021-08-19 09:16:00 +02:00
parent 3afa9757da
commit a70e75b8a4
4 changed files with 18 additions and 58 deletions
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48
examples/c/lexcalc/parse.y
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@@ -25,10 +25,10 @@
{
// Tell Flex the expected prototype of yylex.
#define YY_DECL \
yytoken_kind_t yylex (YYSTYPE* yylval, YYLTYPE *yylloc)
yytoken_kind_t yylex (YYSTYPE* yylval, YYLTYPE *yylloc, int *nerrs)
YY_DECL;
void yyerror (const YYLTYPE *loc, const char *msg);
void yyerror (const YYLTYPE *loc, int *nerrs, const char *msg);
}
// Emitted on top of the implementation file.
@@ -62,6 +62,9 @@
// Enable debug traces (see yydebug in main).
%define parse.trace
// Error count, exchanged between main, yyparse and yylex.
%param {int *nerrs}
%token
PLUS "+"
MINUS "-"
@@ -73,11 +76,9 @@
;
%token <int> NUM "number"
%type <int> exp expression line
%type <int> exp
%printer { fprintf (yyo, "%d", $$); } <int>
%start input expression NUM
// Precedence (from lowest to highest) and associativity.
%left "+" "-"
%left "*" "/"
@@ -90,12 +91,8 @@ input:
;
line:
exp EOL { $$ = $exp; printf ("%d\n", $$); }
| error EOL { $$ = 0; yyerrok; }
;
expression:
exp EOL { $$ = $exp; }
exp EOL { printf ("%d\n", $exp); }
| error EOL { yyerrok; }
;
exp:
@@ -106,7 +103,7 @@ exp:
{
if ($3 == 0)
{
yyerror (&@$, "error: division by zero");
yyerror (&@$, nerrs, "error: division by zero");
YYERROR;
}
else
@@ -118,41 +115,24 @@ exp:
%%
// Epilogue (C code).
void yyerror (const YYLTYPE *loc, const char *msg)
void yyerror (const YYLTYPE *loc, int *nerrs, const char *msg)
{
YYLOCATION_PRINT (stderr, loc);
fprintf (stderr, ": %s\n", msg);
++*nerrs;
}
int main (int argc, const char *argv[])
{
// Possibly enable parser runtime debugging.
yydebug = !!getenv ("YYDEBUG");
int parse_expression_p = 0;
int nerrs = 0;
// Enable parse traces on option -p.
for (int i = 1; i < argc; ++i)
if (strcmp (argv[i], "-e") == 0)
parse_expression_p = 1;
else if (strcmp (argv[i], "-p") == 0)
if (strcmp (argv[i], "-p") == 0)
yydebug = 1;
if (parse_expression_p)
{
yyparse_expression_t res = yyparse_expression ();
nerrs = res.yynerrs;
if (res.yystatus == 0)
printf ("expression: %d\n", res.yyvalue);
else
printf ("expression: failure\n");
}
else
nerrs = yyparse_input ().yynerrs;
if (nerrs)
fprintf (stderr, "errors: %d\n", nerrs);
int nerrs = 0;
yyparse (&nerrs);
// Exit on failure if there were errors.
return !!nerrs;
}