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use these for all user-declared grammar symbols for which the user does not declare a specific %printer/%destructor. Thus, the parser uses it for token 0 if the user declares it but not if Bison generates it as $end. Discussed starting at <http://lists.gnu.org/archive/html/bison-patches/2006-02/msg00064.html>, <http://lists.gnu.org/archive/html/bison-patches/2006-06/msg00091.html>, and <http://lists.gnu.org/archive/html/bison-patches/2006-07/msg00019.html>. * NEWS (2.3+): Mention. * doc/bison.texinfo (Actions in Mid-Rule): It's no longer impossible to declare a %destructor for a mid-rule's semantic value. It's just impossible to declare one specific to it. (Freeing Discarded Symbols): Mention that @$ can be used in %destructor code. Describe default %destructor form. * src/parse-gram.y (grammar_declaration): Parse default %printer/%destructor declarations. * src/output.c (symbol_destructors_output): Use symbol_destructor_get and symbol_destructor_location_get rather than accessing the destructor and destructor_location members of struct symbol. (symbol_printers_output): Likewise but for %printer's. * src/reader.c (symbol_should_be_used): Likewise but for %destructor's again. * src/symtab.c (default_destructor, default_destructor_location, default_printer, default_printer_location): New static global variables to record the default %destructor and %printer. (symbol_destructor_get, symbol_destructor_location_get, symbol_printer_get, symbol_printer_location_get): New functions to compute the appropriate %destructor and %printer for a symbol. (default_destructor_set, default_printer_set): New functions to set the default %destructor and %printer. * src/symtab.h: Prototype all those new functions. * tests/actions.at (Default %printer and %destructor): New test to check that the right %printer and %destructor are called, that they're not called for $end, and that $$ and @$ work correctly. (Default %printer and %destructor for user-declared end token): New test to check that the default %printer and %destructor are called for a user-declared end token. * tests/input.at (Default %printer and %destructor redeclared, Unused values with default %destructor): New tests to check related grammar warnings and errors.
This directory contains the Bison parser generator. See the file INSTALL for generic compilation and installation instructions. See the file doc/FAQ for frequently asked questions. Bison requires GNU m4 1.4.3 or later. See: ftp://ftp.gnu.org/gnu/m4/m4-1.4.3.tar.gz Bison can work with pre-1.4.3 distributions of GNU m4 if they are sufficiently patched, but if you encounter a bug with an older distribution and report a bug we will probably suggest that you upgrade to 1.4.3 as the first step in trying to fix it. 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. If you have questions about using Bison and the documentation does not answer them, please send mail to <help-bison@gnu.org>. ----- Copyright (C) 1992, 1998, 1999, 2003, 2004, 2005 Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. Bison 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 2, or (at your option) any later version. Bison 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 autoconf; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.