yysyntax_error: prepare for readability of next patches.

[bison.git] / data / bison.m4

diff --git a/data/bison.m4 b/data/bison.m4
index 014f10f8a1fabea5539fc662d1317c496f6134f8..81337d302c820aaab2800d28d6cab61c9d76942d 100644 (file)
--- a/data/bison.m4
+++ b/data/bison.m4
@@ -1,8 +1,9 @@
                                                             -*- Autoconf -*-
 
 # Language-independent M4 Macros for Bison.
-# Copyright (C) 2002, 2004, 2005, 2006, 2007, 2008, 2009 Free Software
-# Foundation, Inc.
+
+# Copyright (C) 2002, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free
+# Software Foundation, Inc.
 
 # 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
@@ -362,10 +363,26 @@ m4_popdef([b4_start])dnl
 m4_popdef([b4_end])dnl
 ])])
 
-# b4_percent_define_get(VARIABLE)
+
+
+
+## --------------------- ##
+## b4_percent_define_*.  ##
+## --------------------- ##
+
+
+# b4_percent_define_use(VARIABLE)
 # -------------------------------
-# Mimic muscle_percent_define_get in ../src/muscle-tab.h exactly.  That is, if
-# the %define variable VARIABLE is defined, emit its value.  Also, record
+# Declare that VARIABLE was used.
+m4_define([b4_percent_define_use],
+[m4_define([b4_percent_define_bison_variables(]$1[)])dnl
+])
+
+# b4_percent_define_get(VARIABLE, [DEFAULT])
+# ------------------------------------------
+# Mimic muscle_percent_define_get in ../src/muscle-tab.h.  That is, if
+# the %define variable VARIABLE is defined, emit its value.  Contrary
+# to its C counterpart, return DEFAULT otherwise.  Also, record
 # Bison's usage of VARIABLE by defining
 # b4_percent_define_bison_variables(VARIABLE).
 #
@@ -373,8 +390,11 @@ m4_popdef([b4_end])dnl
 #
 #   b4_percent_define_get([[foo]])
 m4_define([b4_percent_define_get],
-[m4_define([b4_percent_define_bison_variables(]$1[)])dnl
-m4_ifdef([b4_percent_define(]$1[)], [m4_indir([b4_percent_define(]$1[)])])])
+[b4_percent_define_use([$1])dnl
+m4_ifdef([b4_percent_define(]$1[)],
+         [m4_indir([b4_percent_define(]$1[)])],
+         [$2])])
+
 
 # b4_percent_define_get_loc(VARIABLE)
 # -----------------------------------