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# ===========================================================================
# https://www.gnu.org/software/autoconf-archive/ax_var_push.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_VAR_PUSHVALUE(VARIABLE, [VALUE])
#
# DESCRIPTION
#
# Stores a copy of variable_name's value and assigns it to 'value' If no
# value is given, its original value is kept. Compile, link and running
# tests usually require the programmer to provide additional flags.
# However, it is strongly recommended not to override flags defined by the
# user through the configure command. AX_VAR_PUSHVALUE and AX_VAR_POPVALUE
# are clean way to temporarily store a variable's value and restore it
# later, using a stack-like behaviour. This macro supports nesting.
#
# Example:
#
# AX_VAR_PUSHVALUE([CXXFLAGS],["my test flags"])
# perform some checks with CXXFLAGS...
# CXXFLAGS value will be "my test flags"
# AX_VAR_POPVALUE([CXXFLAGS])
# CXXFLAGS is restored to its original value
#
# LICENSE
#
# Copyright (c) 2015 Jorge Bellon <jbelloncastro@gmail.com>
#
# 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 <https://www.gnu.org/licenses/>.
#
# As a special exception, the respective Autoconf Macro's copyright owner
# gives unlimited permission to copy, distribute and modify the configure
# scripts that are the output of Autoconf when processing the Macro. You
# need not follow the terms of the GNU General Public License when using
# or distributing such scripts, even though portions of the text of the
# Macro appear in them. The GNU General Public License (GPL) does govern
# all other use of the material that constitutes the Autoconf Macro.
#
# This special exception to the GPL applies to versions of the Autoconf
# Macro released by the Autoconf Archive. When you make and distribute a
# modified version of the Autoconf Macro, you may extend this special
# exception to the GPL to apply to your modified version as well.
#serial 3
AC_DEFUN([AX_VAR_PUSHVALUE],[
increment([$1_counter])
AS_VAR_PUSHDEF([variable],[$1]) dnl
AS_VAR_PUSHDEF([backup],[save_$1_]$1_counter) dnl
AS_VAR_SET(backup,$variable) dnl
AS_VAR_SET(variable,["]m4_default($2,$variable)["]) dnl
AS_VAR_POPDEF([variable]) dnl
AS_VAR_POPDEF([backup]) dnl
])dnl AX_PUSH_VAR
AC_DEFUN([AX_VAR_POPVALUE],[
AS_VAR_PUSHDEF([variable],[$1]) dnl
AS_VAR_PUSHDEF([backup],[save_$1_]$1_counter) dnl
AS_VAR_SET(variable,$backup) dnl
decrement([$1_counter])
AS_VAR_POPDEF([variable]) dnl
AS_VAR_POPDEF([backup]) dnl
])dnl AX_POP_VAR
# -------------------------
# Auxiliary macro
# -------------------------
# increment(counter_name)
#
# Increment the value of a named counter.
# Initialize to 1 if not defined
# -------------------------
m4_define([increment],[dnl
m4_ifdef([$1],dnl
[m4_define([$1],m4_incr($1))],dnl
[m4_define([$1],[1])]dnl
)dnl
])dnl
# -------------------------
# Auxiliary macro
# -------------------------
# decrement(counter_name)
#
# Decrement the value of a named counter.
# Throws an error if counter not defined
# or value reaches zero.
# -------------------------
m4_define([decrement],[dnl
m4_ifdef([$1],dnl
[m4_if(m4_eval($1 > 0),
[1],m4_define([$1],m4_decr($1)),dnl
[m4_fatal([Missing call to AX_VAR_PUSHVALUE with var $1])]dnl
)],dnl
[m4_fatal([Missing call to AX_VAR_PUSHVALUE with var $1])])dnl
])dnl
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