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examples: clean up

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* examples/c/calc/calc.y: Restore to its original state, with
parse.error=detailed instead of parse.error=custom (this example
should be simple).
* examples/c/calc/calc.test: Check syntax errors.
* examples/c/lexcalc/parse.y: Add comments.
This commit is contained in:
Akim Demaille
2020-01-25 07:59:26 +01:00
parent 0917f4dc76
commit c592202345
5 changed files with 42 additions and 58 deletions
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6
examples/c/calc/calc.test
View File

@@ -34,4 +34,10 @@ cat >input <<EOF
(1+2) * 3
EOF
run 0 9
# Check the traces.
run -noerr 0 9 -p
cat >input <<EOF
1++2
EOF
run 0 "err: syntax error, unexpected '+', expecting number or '('"

67
examples/c/calc/calc.y
View File

@@ -1,50 +1,35 @@
%code top {
#include <ctype.h> /* isdigit. */
#include <stdbool.h>
#include <stdio.h> /* For printf, etc. */
#include <string.h> /* strcmp. */
int yylex (void);
void yyerror (char const *);
bool show_expected = false;
#define PRINT_EXPECTED_TOKENS() \
do { \
if (show_expected) \
{ \
yyparse_context_t ctx \
= {yyssp, yytoken, yyesa, &yyes, &yyes_capacity}; \
int tokens[YYNTOKENS]; \
int cnt = yyexpected_tokens (&ctx, tokens, YYNTOKENS); \
fprintf (stderr, "expected tokens in state %d rule %d (%d):", \
*yyssp, yyn - 1, cnt); \
for (int i = 0; i < cnt; ++i) \
fprintf (stderr, " %s", yysymbol_name(tokens[i])); \
fprintf (stderr, "\n"); \
} \
} while (0)
}
%define api.header.include {"calc.h"}
%define api.value.type union /* Generate YYSTYPE from these types: */
%define parse.error custom
%define parse.lac full
/* Generate YYSTYPE from the types used in %token and %type. */
%define api.value.type union
%token <double> NUM "number"
%type <double> expr term fact
/* Generate the parser description file. */
/* Generate the parser description file (calc.output). */
%verbose
/* Nice error messages with details. */
%define parse.error detailed
/* Enable run-time traces (yydebug). */
%define parse.trace
/* Formatting semantic values. */
/* Formatting semantic values in debug traces. */
%printer { fprintf (yyo, "%g", $$); } <double>;
%% /* The grammar follows. */
input:
%empty { PRINT_EXPECTED_TOKENS (); }
| input line { PRINT_EXPECTED_TOKENS (); }
%empty
| input line
;
line:
@@ -66,34 +51,12 @@ term:
;
fact:
"number" { PRINT_EXPECTED_TOKENS (); }
| '(' expr { PRINT_EXPECTED_TOKENS (); } ')' { $$ = $expr; }
"number"
| '(' expr ')' { $$ = $2; }
;
%%
int
yyreport_syntax_error (const yyparse_context_t *ctx)
{
enum { YYERROR_VERBOSE_ARGS_MAXIMUM = 10 };
/* Arguments of yyformat: reported tokens (one for the "unexpected",
one per "expected"). */
int arg[YYERROR_VERBOSE_ARGS_MAXIMUM];
int n = yysyntax_error_arguments (ctx, arg, sizeof arg / sizeof *arg);
if (n == -2)
return 2;
fprintf (stderr, "SYNTAX ERROR on token [%s]", yysymbol_name (arg[0]));
if (1 < n)
{
fprintf (stderr, " (expected:");
for (int i = 1; i < n; ++i)
fprintf (stderr, " [%s]", yysymbol_name (arg[i]));
fprintf (stderr, ")");
}
fprintf (stderr, "\n");
return 0;
}
int
yylex (void)
{
@@ -130,9 +93,7 @@ main (int argc, char const* argv[])
{
/* Enable parse traces on option -p. */
for (int i = 1; i < argc; ++i)
if (!strcmp (argv[i], "-e"))
show_expected = 1;
else if (!strcmp (argv[i], "-p"))
if (!strcmp (argv[i], "-p"))
yydebug = 1;
return yyparse ();
}