Add ax_var_pop.m4 and ax_var_push.m4 macros.

1 files changed, 96 insertions, 0 deletions

diff --git a/m4/ax_var_push.m4 b/m4/ax_var_push.m4
new file mode 100644
index 0000000..d8d9718
--- /dev/null
+++ b/m4/ax_var_push.m4
@@ -0,0 +1,96 @@
+# ===========================================================================
+#        http://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 <http://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 1
+
+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