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* data/skeletons/lalr1.java: More comments.
(Context.EMPTY): Remove.
* doc/bison.texi (Java Parser Context Interface): New.
This commit is contained in:
Akim Demaille
2020-04-06 14:48:35 +02:00
parent 3dcfb4fd88
commit 11225a5d2f
2 changed files with 85 additions and 11 deletions
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doc/bison.texi
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@@ -433,6 +433,7 @@ Java Parsers
* Java Semantic Values:: %token and %nterm vs. Java
* Java Location Values:: The position and location classes
* Java Parser Interface:: Instantiating and running the parser
* Java Parser Context Interface:: Circumstances of a syntax error
* Java Scanner Interface:: Specifying the scanner for the parser
* Java Action Features:: Special features for use in actions
* Java Push Parser Interface:: Instantiating and running the a push parser
@@ -12673,6 +12674,7 @@ main (int argc, char *argv[])
* Java Semantic Values:: %token and %nterm vs. Java
* Java Location Values:: The position and location classes
* Java Parser Interface:: Instantiating and running the parser
* Java Parser Context Interface:: Circumstances of a syntax error
* Java Scanner Interface:: Specifying the scanner for the parser
* Java Action Features:: Special features for use in actions
* Java Push Parser Interface:: Instantiating and running the a push parser
@@ -12917,6 +12919,37 @@ Identify the Bison version and skeleton used to generate this parser.
@end deftypecv
@node Java Parser Context Interface
@subsection Java Parser Context Interface
The parser context provides information to build error reports when you
invoke @samp{%define parse.error custom}.
@deftypemethod {YYParser.Context} {YYParser.SymbolKind} getToken ()
The kind of the lookahead. Maybe return @code{null} when there is no
lookahead.
@end deftypemethod
@deftypemethod {YYParser.Context} {YYParser.Location} getLocation ()
The location of the lookahead.
@end deftypemethod
@deftypemethod {YYParser.Context} {int} getExpectedTokens (@code{YYParser.SymbolKind[]} @var{argv}, @code{int} @var{argc})
Fill @var{argv} with the expected tokens, which never includes
@code{YYSYMBOL_YYEMPTY}, @code{YYSYMBOL_YYERROR}, or
@code{YYSYMBOL_YYUNDEF}.
Never put more than @var{argc} elements into @var{argv}, and on success
return the effective number of tokens stored in @var{argv}. Return 0 if
there are more than @var{argc} expected tokens, yet fill @var{argv} up to
@var{argc}. When LAC is enabled, may return a negative number on errors,
such as @code{YYNOMEM} on memory exhaustion.
If @var{argv} is null, return the size needed to store all the possible
values, which is always less than @code{YYNTOKENS}.
@end deftypemethod
@node Java Scanner Interface
@subsection Java Scanner Interface
@c - %code lexer
@@ -12979,6 +13012,40 @@ The return type can be changed using @samp{%define api.value.type
@{@var{class-name}@}}.
@end deftypemethod
@deftypemethod {Lexer} {void} reportSyntaxError (@code{YYParser.Context} @var{ctx})
If you invoke @samp{%define parse.error custom} (@pxref{Bison
Declarations}), then the parser no longer passes syntax error messages to
@code{yyerror}, rather it delegates that task to the user by calling the
@code{reportSyntaxError} function.
Whether it uses @code{yyerror} is up to the user.
Here is a typical example of a reporting function.
@example
public void yyreportSyntaxError (YYParser.Context ctx)
@{
System.err.print (ctx.getLocation () + ": syntax error");
// Report the expected tokens.
@{
final int TOKENMAX = 5;
YYParser.SymbolKind[] arg = new YYParser.SymbolKind[TOKENMAX];
int n = ctx.getExpectedTokens (arg, TOKENMAX);
for (int i = 0; i < n; ++i)
System.err.print ((i == 0 ? ": expected " : " or ")
+ ctx.yysymbolName (arg[i]));
@}
// Report the unexpected token which triggered the error.
@{
YYParser.SymbolKind lookahead = ctx.getToken ();
if (lookahead != null)
System.err.print (" before " + ctx.yysymbolName (lookahead));
@}
System.err.println ("");
@}
@end example
@end deftypemethod
@node Java Action Features
@subsection Special Features for Use in Java Actions