Future/bison
1
0
Fork 0
mirror of https://git.savannah.gnu.org/git/bison.git synced 2026-03-09 12:23:04 +00:00
Code Issues Packages Projects Releases Wiki Activity

doc: document new features of parse.error

Browse Source 
* doc/bison.texi (Error Reporting): Rename as...
(Error Reporting Function): this.
Adjust dependencies.
Make it a subsection of this...
(Error Reporting): new section.
(Syntax Error Reporting Function): New.
(parse.error): Update description.
This commit is contained in:
Akim Demaille
2020-01-25 17:26:59 +01:00
parent 792fc34016
commit 23ba9e5dfa
2 changed files with 179 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

65
NEWS
View File

@@ -14,6 +14,67 @@ GNU Bison NEWS
(2013-07-25), "%error-verbose" is deprecated in favor of "%define
parse.error verbose".
** New features
*** Improved syntax error messages
Two new values for the %define parse.error variable offer more control to
the user.
**** %define parse.error detailed
The behavior of "%define parse.error detailed" is closely resembling that
of "%define parse.error verbose" with a few exceptions. First, it is safe
to use non-ASCII characters in token aliases (with 'verbose', the result
depends on the locale with which bison was run). Second, a yysymbol_name
function is exposed to the user, instead of the yytnamerr function and the
yytname table. Third, token internationalization is supported (see
below).
**** %define parse.error custom
With this directive, the user forges and emits the syntax error message
herself by defining a function such as:
int
yyreport_syntax_error (const yyparse_context_t *ctx)
{
enum { ARGMAX = 10 };
int arg[ARGMAX];
int n = yysyntax_error_arguments (ctx, arg, ARGMAX);
if (n == -2)
return 2; // Memory exhausted.
YY_LOCATION_PRINT (stderr, *yyparse_context_location (ctx));
fprintf (stderr, ": syntax error");
for (int i = 1; i < n; ++i)
fprintf (stderr, " %s %s",
i == 1 ? "expected" : "or", yysymbol_name (arg[i]));
if (n)
fprintf (stderr, " before %s", yysymbol_name (arg[0]));
fprintf (stderr, "\n");
return 0;
}
**** Token aliases internationalization
When the %define variable parse.error is set to `custom` or `detailed`,
one may use the _() annotation to specify which token aliases are to be
translated. For instance
%token
PLUS "+"
MINUS "-"
EOF 0 _("end of file")
<double>
NUM _("double precision number")
<symrec*>
FUN _("function")
VAR _("variable")
In that case the user must define _() and N_(), and yysymbol_name returns
the translated symbol (i.e., it returns '_("variable")' rather that
'"variable"').
* Noteworthy changes in release 3.5.1 (2020-01-19) [stable]
** Bug fixes
@@ -3881,7 +3942,9 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
LocalWords: Wdeprecated yytext Variadic variadic yyrhs yyphrs RCS README
LocalWords: noexcept constexpr ispell american deprecations backend Teoh
LocalWords: YYPRINT Mangold Bonzini's Wdangling exVal baz checkable gcc
LocalWords: fsanitize Vogelsgesang lis redeclared stdint automata
LocalWords: fsanitize Vogelsgesang lis redeclared stdint automata yytname
LocalWords: yysymbol yytnamerr yyreport ctx ARGMAX yysyntax stderr
LocalWords: symrec
Local Variables:
ispell-dictionary: "american"