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java: introduce yyexpectedTokens

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And allow syntax error messages for 'detailed' and 'verbose' to be
translated.

* data/skeletons/lalr1.java (Context, yyexpectedTokens)
(yysyntaxErrorArguments): New.
(yysyntax_error): Use it.
This commit is contained in:
Akim Demaille
2020-02-07 06:09:10 +01:00
parent 52db24b2bc
commit 088356cb2f
1 changed files with 101 additions and 63 deletions
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164
data/skeletons/lalr1.java
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@@ -82,6 +82,7 @@ m4_define([b4_define_state],[[
]])[
]b4_user_pre_prologue[
]b4_user_post_prologue[
import java.text.MessageFormat;
]b4_percent_code_get([[imports]])[
/**
* A Bison parser, automatically generated from <tt>]m4_bpatsubst(b4_file_name, [^"\(.*\)"$], [\1])[</tt>.
@@ -673,7 +674,10 @@ b4_dollar_popdef[]dnl
++yynerrs;
if (yychar == yyempty_)
yytoken = yyempty_;
yyerror (]b4_locations_if([yylloc, ])[yysyntax_error (yystate, yytoken));
Context yyctx = new Context ();
yyctx.yystack = yystack;
yyctx.yytoken = yytoken;
yyerror (]b4_locations_if([yylloc, ])[yysyntax_error (yyctx));
}
]b4_locations_if([[
@@ -851,74 +855,108 @@ b4_dollar_popdef[]dnl
}
]])[
public final class Context
{
public YYStack yystack;
public int yytoken;
};
/* Put in YYARG at most YYARGN of the expected tokens given the
current YYCTX, and return the number of tokens stored in YYARG. If
YYARG is null, return the number of expected tokens (guaranteed to
be less than YYNTOKENS). */
static int
yyexpectedTokens (Context yyctx,
int yyarg[], int yyoffset, int yyargn)
{
int yycount = yyoffset;
int yyn = yypact_[yyctx.yystack.stateAt (0)];
if (!yyPactValueIsDefault (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_;
for (int x = yyxbegin; x < yyxend; ++x)
if (yycheck_[x + yyn] == x && x != yy_error_token_
&& !yyTableValueIsError (yytable_[x + yyn]))
{
if (yyarg == null)
yycount += 1;
else if (yycount == yyargn)
return 0; // FIXME: this is incorrect.
else
yyarg[yycount++] = x;
}
}
return yycount - yyoffset;
}
static int
yysyntaxErrorArguments (Context yyctx,
int[] yyarg, int yyargn)
{
/* There are many possibilities here to consider:
- 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.
*/
int yycount = 0;
if (yyctx.yytoken != yyempty_)
{
yyarg[yycount++] = yyctx.yytoken;
yycount += yyexpectedTokens (yyctx, yyarg, 1, yyargn);
}
return yycount;
}
// Generate an error message.
private String yysyntax_error (int yystate, int tok)
private String yysyntax_error (Context yyctx)
{]b4_error_verbose_if([[
if (yyErrorVerbose)
{
/* There are many possibilities here to consider:
- 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_)
int[] yyarg = new int[5];
int yycount = yysyntaxErrorArguments (yyctx, yyarg, 5);
String[] yystr = new String[yycount];
for (int yyi = 0; yyi < yycount; ++yyi)
yystr[yyi] = yysymbolName (yyarg[yyi]);
MessageFormat yyformat;
switch (yycount)
{
/* FIXME: This method of building the message is not compatible
with internationalization. */
StringBuffer res =
new StringBuffer ("syntax error, unexpected ");
res.append (yysymbolName (tok));
int yyn = yypact_[yystate];
if (!yyPactValueIsDefault (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_
&& !yyTableValueIsError (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_
&& !yyTableValueIsError (yytable_[x + yyn]))
{
res.append (count++ == 0 ? ", expecting " : " or ");
res.append (yysymbolName (x));
}
}
}
return res.toString ();
default:
case 0: yyformat = new MessageFormat ("syntax error"); break;
case 1: yyformat = new MessageFormat ("syntax error, unexpected {0}"); break;
case 2: yyformat = new MessageFormat ("syntax error, unexpected {0}, expecting {1}"); break;
case 3: yyformat = new MessageFormat ("syntax error, unexpected {0}, expecting {1} or {2}"); break;
case 4: yyformat = new MessageFormat ("syntax error, unexpected {0}, expecting {1} or {2} or {3}"); break;
case 5: yyformat = new MessageFormat ("syntax error, unexpected {0}, expecting {1} or {2} or {3} or {4}"); break;
}
return yyformat.format (yystr);
}
]])[
return "syntax error";