mirror of
https://git.savannah.gnu.org/git/bison.git
synced 2026-03-09 04:13:03 +00:00
4e19ab9fcd
Currently when --defines is used, we generate a header, and paste an exact copy of it into the generated parser implementation file. Let's provide a means to #include it instead. We don't do it by default because of the Autotools' ylwrap. This program wraps invocations of yacc (that uses a fixed output name: y.tab.c, y.tab.h, y.output) to support a more modern naming scheme (dir/foo.y -> dir/foo.tab.c, dir/foo.tab.h, etc.). It does that by renaming the generated files, and then by running sed to propagate these renamings inside the files themselves. Unfortunately Automake's Makefiles uses Bison as if it were Yacc (with --yacc or with -o y.tab.c) and invoke bison via ylwrap. As a consequence, as far as Bison is concerned, the output files are y.tab.c and y.tab.h, so it emits '#include "y.tab.h"'. So far, so good. But now ylwrap processes this '#include "y.tab.h"' into '#include "dir/foo.tab.h"', which is not guaranteed to always work. So, let's do the Right Thing when the output file is not y.tab.c, in which case the user should %define api.header.include. Binding this behavior to --yacc is tempting, but we recently told people to stop using --yacc (as it also enables the Yacc warnings), but rather to use -o y.tab.c. Yacc.c is the only skeleton concerned: all the others do include their header. * data/skeletons/yacc.c (b4_header_include_if): New. (api.header.include): Provide a default value when the output is not y.tab.c. * src/parse-gram.y (api.header.include): Define.
This directory contains examples of Bison grammar files, sorted per language.
Several of them come from the documentation, which should be installed together with Bison. The URLs are provided for convenience.
These examples come with a README and a Makefile. Not only can they be used to toy with Bison, they can also be starting points for your own grammars.
Please, be sure to read the C examples before looking at the other languages, as these examples are simpler.