[grilo] build: Add vapigen.m4 file

[Bastien Nocera <hadess src gnome org>]

commit 7a7ccfc43d558e5b6f425498fd8be9d2664eabd0
Author: Bastien Nocera <hadess hadess net>
Date:   Thu Jan 22 13:24:14 2015 +0100

    build: Add vapigen.m4 file
    
    To avoid errors during autogen.sh if vala is not present on the
    system.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=742645

 m4/vapigen.m4 |  101 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 101 insertions(+), 0 deletions(-)
---
diff --git a/m4/vapigen.m4 b/m4/vapigen.m4
new file mode 100644
index 0000000..2c435e7
--- /dev/null
+++ b/m4/vapigen.m4
@@ -0,0 +1,101 @@
+dnl vapigen.m4
+dnl
+dnl Copyright 2012 Evan Nemerson
+dnl
+dnl This library is free software; you can redistribute it and/or
+dnl modify it under the terms of the GNU Lesser General Public
+dnl License as published by the Free Software Foundation; either
+dnl version 2.1 of the License, or (at your option) any later version.
+dnl
+dnl This library is distributed in the hope that it will be useful,
+dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
+dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+dnl Lesser General Public License for more details.
+dnl
+dnl You should have received a copy of the GNU Lesser General Public
+dnl License along with this library; if not, write to the Free Software
+dnl Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
+
+# VAPIGEN_CHECK([VERSION], [API_VERSION], [FOUND_INTROSPECTION], [DEFAULT])
+# --------------------------------------
+# Check vapigen existence and version
+#
+# See http://live.gnome.org/Vala/UpstreamGuide for detailed documentation
+AC_DEFUN([VAPIGEN_CHECK],
+[
+  AS_IF([test "x$3" != "xyes"], [
+      m4_provide_if([GOBJECT_INTROSPECTION_CHECK], [], [
+          m4_provide_if([GOBJECT_INTROSPECTION_REQUIRE], [], [
+              AC_MSG_ERROR([[You must call GOBJECT_INTROSPECTION_CHECK or GOBJECT_INTROSPECTION_REQUIRE 
before using VAPIGEN_CHECK unless using the FOUND_INTROSPECTION argument is "yes"]])
+            ])
+        ])
+    ])
+
+  AC_ARG_ENABLE([vala],
+    [AS_HELP_STRING([--enable-vala[=@<:@no/auto/yes@:>@]],[build Vala bindings 
@<:@default=]ifelse($4,,auto,$4)[@:>@])],,[
+      AS_IF([test "x$4" = "x"], [
+          enable_vala=auto
+        ], [
+          enable_vala=$4
+        ])
+    ])
+
+  AS_CASE([$enable_vala], [no], [enable_vala=no],
+      [yes], [
+        AS_IF([test "x$3" != "xyes" -a "x$found_introspection" != "xyes"], [
+            AC_MSG_ERROR([Vala bindings require GObject Introspection])
+          ])
+      ], [auto], [
+        AS_IF([test "x$3" != "xyes" -a "x$found_introspection" != "xyes"], [
+            enable_vala=no
+          ])
+      ], [
+        AC_MSG_ERROR([Invalid argument passed to --enable-vala, should be one of @<:@no/auto/yes@:>@])
+      ])
+
+  AS_IF([test "x$2" = "x"], [
+      vapigen_pkg_name=vapigen
+    ], [
+      vapigen_pkg_name=vapigen-$2
+    ])
+  AS_IF([test "x$1" = "x"], [
+      vapigen_pkg="$vapigen_pkg_name"
+    ], [
+      vapigen_pkg="$vapigen_pkg_name >= $1"
+    ])
+
+  PKG_PROG_PKG_CONFIG
+
+  PKG_CHECK_EXISTS([$vapigen_pkg], [
+      AS_IF([test "$enable_vala" = "auto"], [
+          enable_vala=yes
+        ])
+    ], [
+      AS_CASE([$enable_vala], [yes], [
+          AC_MSG_ERROR([$vapigen_pkg not found])
+        ], [auto], [
+          enable_vala=no
+        ])
+    ])
+
+  AC_MSG_CHECKING([for vapigen])
+
+  AS_CASE([$enable_vala],
+    [yes], [
+      VAPIGEN=`$PKG_CONFIG --variable=vapigen $vapigen_pkg_name`
+      VAPIGEN_MAKEFILE=`$PKG_CONFIG --variable=datadir $vapigen_pkg_name`/vala/Makefile.vapigen
+      AS_IF([test "x$2" = "x"], [
+          VAPIGEN_VAPIDIR=`$PKG_CONFIG --variable=vapidir $vapigen_pkg_name`
+        ], [
+          VAPIGEN_VAPIDIR=`$PKG_CONFIG --variable=vapidir_versioned $vapigen_pkg_name`
+        ])
+    ])
+
+  AC_MSG_RESULT([$enable_vala])
+
+  AC_SUBST([VAPIGEN])
+  AC_SUBST([VAPIGEN_VAPIDIR])
+  AC_SUBST([VAPIGEN_MAKEFILE])
+
+  AM_CONDITIONAL(ENABLE_VAPIGEN, test "x$enable_vala" = "xyes")
+])