mirror of
https://git.savannah.gnu.org/git/bison.git
synced 2026-03-09 12:23:04 +00:00
97ae878ec3
The current approach was too adhoc: the symbols were not sufficiently self-contained, in particular wrt memory management. The "new" guideline is the one that should have been followed from the start: let the symbols handle themslves, instead of leaving their users to it. It was justified by the will to avoid gratuitious moves and copies, but the current approach does not seem to be slower, yet it will probably be simpler to adjust to support move semantics from C++11. The documentation says that the %parse-param are available from the %destructor. In retrospect, that was a silly design decision, which we can break for variants, as its a new feature. It should be phased out for non-variants too. * data/variant.hh: A variant never knows if it stores something or not, it is up to its users to store this information. Yet, in parse.assert mode, make sure the empty/filled variants are properly used. (b4_symbol_constructor_define_): Don't call directly the symbol constructor, to save a useless temporary. * data/stack.hh (push): Steal the pushed value instead of duplicating it. This will simplify the callers of push, who handled this "move" approach themselves. * data/c++.m4 (basic_symbol): Let -1, as kind, denote the fact that a symbol is empty. This is needed for instance when shifting the lookahead: yyla is given as argument to "push", and its value is then moved on the stack. But then yyla must be declared "empty" so that its destructor won't be called. (basic_symbol::move): New. Move the responsibility of calling the destructor from yy_destroy to ~basic_symbol in the case of variants. * data/lalr1.cc (stack_symbol_type): Now a derived class from its previous value, so that we can add a constructor from a symbol_type. (by_state): State -1 means empty. (yypush_): Factor, by calling one overload from the other one, and using the new semantics of stack::push. No longer reclaim by hand the memory from rhs symbols, since now that we store objects with proper destructors, they will be reclaimed automatically. Conversely, be sure to delete yylhs. * tests/c++.at (C++ Variant-based Symbols): New "unit" test for symbols.
This package contains the GNU Bison parser generator.
* Installation
** Build
See the file INSTALL for generic compilation and installation
instructions.
Bison requires GNU m4 1.4.6 or later. See:
ftp://ftp.gnu.org/gnu/m4/m4-1.4.6.tar.gz
** Internationalization
Bison supports two catalogues: one for Bison itself (i.e., for the
maintainer-side parser generation), and one for the generated parsers
(i.e., for the user-side parser execution). The requirements between
both differ: bison needs ngettext, the generated parsers do not. To
simplify the build system, neither are installed if ngettext is not
supported, even if generated parsers could have been localized. See
http://lists.gnu.org/archive/html/bug-bison/2009-08/msg00006.html for
more details.
* Questions
See the section FAQ in the documentation (doc/bison.info) for
frequently asked questions. The documentation is also available in
PDF and HTML, provided you have a recent version of Texinfo installed:
run "make pdf" or "make html".
If you have questions about using Bison and the documentation does
not answer them, please send mail to <help-bison@gnu.org>.
* Bug reports
Please send bug reports to <bug-bison@gnu.org>. Please include the
version number from `bison --version', and a complete, self-contained
test case in each bug report.
* Copyright statements
For any copyright year range specified as YYYY-ZZZZ in this package,
note that the range specifies every single year in that closed interval.
Local Variables:
mode: outline
End:
-----
Copyright (C) 1992, 1998-1999, 2003-2005, 2008-2013 Free Software
Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.