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d: obey parse.error

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* data/skeletons/lalr1.d (yysyntax_error): Let the dispatch be
bison-time, not runtime.
This commit is contained in:
Akim Demaille
2019-12-07 10:09:24 +01:00
parent 9bf06f6963
commit 046f238826
2 changed files with 67 additions and 77 deletions
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140
data/skeletons/lalr1.d
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@@ -187,9 +187,6 @@ b4_user_union_members
{
]b4_identification[
/** True if verbose error messages are enabled. */
public bool errorVerbose = ]b4_flag_value([error_verbose])[;
]b4_locations_if([[
private final ]b4_location_type[ yylloc_from_stack (ref YYStack rhs, int n)
{
@@ -400,7 +397,8 @@ b4_user_union_members
ref ]b4_yystype[ yyvaluep]dnl
b4_locations_if([, ref ]b4_location_type[ yylocationp])[)
{
if (0 < yydebug) {
if (0 < yydebug)
{
string message = s ~ (yytype < yyntokens_ ? " token " : " nterm ")
~ yytname_[yytype] ~ " ("]b4_locations_if([
~ yylocationp.toString() ~ ": "])[;
@@ -667,78 +665,74 @@ m4_popdef([b4_at_dollar])])dnl
// Generate an error message.
private final string yysyntax_error (int yystate, int tok)
{
if (errorVerbose)
{]b4_error_verbose_if([[
/* There are many possibilities here to consider:
- Assume YYFAIL is not used. It's too flawed to consider.
See
<http://lists.gnu.org/archive/html/bison-patches/2009-12/msg00024.html>
for details. YYERROR is fine as it does not invoke this
function.
- If this state is a consistent state with a default action,
then the only way this function was invoked is if the
default action is an error action. In that case, don't
check for expected tokens because there are none.
- The only way there can be no lookahead present (in tok) is
if this state is a consistent state with a default action.
Thus, detecting the absence of a lookahead is sufficient to
determine that there is no unexpected or expected token to
report. In that case, just report a simple "syntax error".
- Don't assume there isn't a lookahead just because this
state is a consistent state with a default action. There
might have been a previous inconsistent state, consistent
state with a non-default action, or user semantic action
that manipulated yychar. (However, yychar is currently out
of scope during semantic actions.)
- Of course, the expected token list depends on states to
have correct lookahead information, and it depends on the
parser not to perform extra reductions after fetching a
lookahead from the scanner and before detecting a syntax
error. Thus, state merging (from LALR or IELR) and default
reductions corrupt the expected token list. However, the
list is correct for canonical LR with one exception: it
will still contain any token that will not be accepted due
to an error action in a later state.
*/
if (tok != yyempty_)
{
/* There are many possibilities here to consider:
- Assume YYFAIL is not used. It's too flawed to consider.
See
<http://lists.gnu.org/archive/html/bison-patches/2009-12/msg00024.html>
for details. YYERROR is fine as it does not invoke this
function.
- If this state is a consistent state with a default action,
then the only way this function was invoked is if the
default action is an error action. In that case, don't
check for expected tokens because there are none.
- The only way there can be no lookahead present (in tok) is
if this state is a consistent state with a default action.
Thus, detecting the absence of a lookahead is sufficient to
determine that there is no unexpected or expected token to
report. In that case, just report a simple "syntax error".
- Don't assume there isn't a lookahead just because this
state is a consistent state with a default action. There
might have been a previous inconsistent state, consistent
state with a non-default action, or user semantic action
that manipulated yychar. (However, yychar is currently out
of scope during semantic actions.)
- Of course, the expected token list depends on states to
have correct lookahead information, and it depends on the
parser not to perform extra reductions after fetching a
lookahead from the scanner and before detecting a syntax
error. Thus, state merging (from LALR or IELR) and default
reductions corrupt the expected token list. However, the
list is correct for canonical LR with one exception: it
will still contain any token that will not be accepted due
to an error action in a later state.
*/
if (tok != yyempty_)
// FIXME: This method of building the message is not compatible
// with internationalization.
string res = "syntax error, unexpected ";
res ~= yytnamerr_ (yytname_[tok]);
int yyn = yypact_[yystate];
if (!yy_pact_value_is_default_ (yyn))
{
// FIXME: This method of building the message is not compatible
// with internationalization.
string res = "syntax error, unexpected ";
res ~= yytnamerr_ (yytname_[tok]);
int yyn = yypact_[yystate];
if (!yy_pact_value_is_default_ (yyn))
{
/* Start YYX at -YYN if negative to avoid negative
indexes in YYCHECK. In other words, skip the first
-YYN actions for this state because they are default
actions. */
int yyxbegin = yyn < 0 ? -yyn : 0;
/* Stay within bounds of both yycheck and yytname. */
int yychecklim = yylast_ - yyn + 1;
int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
int count = 0;
for (int x = yyxbegin; x < yyxend; ++x)
if (yycheck_[x + yyn] == x && x != yy_error_token_
&& !yy_table_value_is_error_ (yytable_[x + yyn]))
++count;
if (count < 5)
{
count = 0;
for (int x = yyxbegin; x < yyxend; ++x)
if (yycheck_[x + yyn] == x && x != yy_error_token_
&& !yy_table_value_is_error_ (yytable_[x + yyn]))
{
res ~= count++ == 0 ? ", expecting " : " or ";
res ~= yytnamerr_ (yytname_[x]);
}
}
}
return res;
/* Start YYX at -YYN if negative to avoid negative
indexes in YYCHECK. In other words, skip the first
-YYN actions for this state because they are default
actions. */
int yyxbegin = yyn < 0 ? -yyn : 0;
/* Stay within bounds of both yycheck and yytname. */
int yychecklim = yylast_ - yyn + 1;
int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
int count = 0;
for (int x = yyxbegin; x < yyxend; ++x)
if (yycheck_[x + yyn] == x && x != yy_error_token_
&& !yy_table_value_is_error_ (yytable_[x + yyn]))
++count;
if (count < 5)
{
count = 0;
for (int x = yyxbegin; x < yyxend; ++x)
if (yycheck_[x + yyn] == x && x != yy_error_token_
&& !yy_table_value_is_error_ (yytable_[x + yyn]))
{
res ~= count++ == 0 ? ", expecting " : " or ";
res ~= yytnamerr_ (yytname_[x]);
}
}
}
}
return res;
}]])[
return "syntax error";
}