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Re: [patch 8/8] Replace Yacc parser with recursive descent parser

Zack Weinberg <> writes:

> 	* gengtype-parse.c: New file.
> 	* gengtype-yacc.y: Delete.
> 	* gengtype-lex.l: Don't include gengtype-yacc.h.
> 	Define YY_DECL and yyterminate appropriately for recursive
> 	descent parser.  yylval is now a string out-parameter to yylex.
> 	(HWS, EOID): New shorthand.
> 	(IWORD): Add a couple more types.
> 	(yylex): Add a setup stanza.  Remove the complex rules for
> 	detecting GTY'ed types and typedefs; replace with simple
> 	keyword detectors.  Adjust everything for the changed
> 	definition of yylval.  Ignore all pp-directives, not just #define.
> 	(yyerror): Delete.
> 	(parse_file): Rename yybegin; do not call yyparse.
> 	(yyend): New.
> 	* gengtype.c (xasprintf): Export again.
> 	(this_file): New.  Use everywhere __FILE__ was being used.
> 	(get_lang_bitmap): Special case types defined in gengtype.c.
> 	(do_typedef, new_structure): Suppress definition of certain types.
> 	(new_structure): Improve diagnostics of duplicate definitions.
> 	Make sure location_s is associated with input.h.
> 	(nreverse_pairs, define_location_structures): New functions.
> 	(main): Improve tagging of kludge types.  Remove old kludges
> 	for input.h types; use define_location_structures.
> 	* gengtype.h: Update prototypes.  Define token codes here.
> 	* Remove all references to gengtype-yacc.
> 	Add rules for gengtype-parse.o.  Adjust rules for gengtype-lex.o
> 	and gengtype.
> 	* bitmap.h (struct bitmap_head_def): Coalesce definitions,
> 	add GTY((skip)) to the field that's only conditionally there.

Several functions in gentype-parse.c need comments.

> +static const char *
> +print_token (int code, const char *value)

The comment on this function should mention that it is a space leak,
and that it doesn't matter.

> +    fields = create_field (0, &scalar_nonchar, "column");
> +    fields = create_field (fields, &scalar_nonchar, "line");
> +    fields = create_field (fields, &string_type, "file");
> +    locs = new_structure ("anon:expanded_location", 0, &pos, fields, 0);
> +
> +    do_typedef ("expanded_location", locs, &pos);
> +    do_scalar_typedef ("location_t", &pos);
> +    do_scalar_typedef ("source_locus", &pos);
> +#else
> +    fields = create_field (0, &scalar_nonchar, "line");
> +    fields = create_field (fields, &string_type, "file");
> +    locs = new_structure ("location_s", 0, &pos, fields, 0);
> +
> +    do_typedef ("expanded_location", locs, &pos);
> +    do_typedef ("location_t", locs, &pos);
> +    do_typedef ("source_locus", create_pointer (locs), &pos);
> +#endif

Please add a comment where these structures are defined indicating
that any change to them requires a change to this file.

OK with those changes.

Thanks for tackling this.


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