Make gobject-introspection dependency non-mandatory

.gitignore

@@ -135,4 +135,5 @@ INSTALL
 configure.ac
 gtk-doc.m4
 test-driver
-m4/
+m4/*
+!m4/introspection.m4

configure.ac.in

@@ -275,6 +275,7 @@ else
 echo "* Mount notification support:         no"
 fi
 echo "* Debug Support:                      $enable_debug"
+echo "* GObject Instrospection support:     $enable_introspection"
 echo
 echo "Additional Plugins:"
 echo

m4/introspection.m4

+dnl -*- mode: autoconf -*-
+dnl Copyright 2009 Johan Dahlin
+dnl
+dnl This file is free software; the author(s) gives unlimited
+dnl permission to copy and/or distribute it, with or without
+dnl modifications, as long as this notice is preserved.
+dnl
+
+# serial 1
+
+m4_define([_GOBJECT_INTROSPECTION_CHECK_INTERNAL],
+[
+    AC_BEFORE([AC_PROG_LIBTOOL],[$0])dnl setup libtool first
+    AC_BEFORE([AM_PROG_LIBTOOL],[$0])dnl setup libtool first
+    AC_BEFORE([LT_INIT],[$0])dnl setup libtool first
+
+    dnl enable/disable introspection
+    m4_if([$2], [require],
+    [dnl
+        enable_introspection=yes
+    ],[dnl
+        AC_ARG_ENABLE(introspection,
+                  AS_HELP_STRING([--enable-introspection[=@<:@no/auto/yes@:>@]],
+                                 [Enable introspection for this build]),, 
+                                 [enable_introspection=auto])
+    ])dnl
+
+    AC_MSG_CHECKING([for gobject-introspection])
+
+    dnl presence/version checking
+    AS_CASE([$enable_introspection],
+    [no], [dnl
+        found_introspection="no (disabled, use --enable-introspection to enable)"
+    ],dnl
+    [yes],[dnl
+        PKG_CHECK_EXISTS([gobject-introspection-1.0],,
+                         AC_MSG_ERROR([gobject-introspection-1.0 is not installed]))
+        PKG_CHECK_EXISTS([gobject-introspection-1.0 >= $1],
+                         found_introspection=yes,
+                         AC_MSG_ERROR([You need to have gobject-introspection >= $1 installed to build AC_PACKAGE_NAME]))
+    ],dnl
+    [auto],[dnl
+        PKG_CHECK_EXISTS([gobject-introspection-1.0 >= $1], found_introspection=yes, found_introspection=no)
+	dnl Canonicalize enable_introspection
+	enable_introspection=$found_introspection
+    ],dnl
+    [dnl	
+        AC_MSG_ERROR([invalid argument passed to --enable-introspection, should be one of @<:@no/auto/yes@:>@])
+    ])dnl
+
+    AC_MSG_RESULT([$found_introspection])
+
+    INTROSPECTION_SCANNER=
+    INTROSPECTION_COMPILER=
+    INTROSPECTION_GENERATE=
+    INTROSPECTION_GIRDIR=
+    INTROSPECTION_TYPELIBDIR=
+    if test "x$found_introspection" = "xyes"; then
+       INTROSPECTION_SCANNER=`$PKG_CONFIG --variable=g_ir_scanner gobject-introspection-1.0`
+       INTROSPECTION_COMPILER=`$PKG_CONFIG --variable=g_ir_compiler gobject-introspection-1.0`
+       INTROSPECTION_GENERATE=`$PKG_CONFIG --variable=g_ir_generate gobject-introspection-1.0`
+       INTROSPECTION_GIRDIR=`$PKG_CONFIG --variable=girdir gobject-introspection-1.0`
+       INTROSPECTION_TYPELIBDIR="$($PKG_CONFIG --variable=typelibdir gobject-introspection-1.0)"
+       INTROSPECTION_CFLAGS=`$PKG_CONFIG --cflags gobject-introspection-1.0`
+       INTROSPECTION_LIBS=`$PKG_CONFIG --libs gobject-introspection-1.0`
+       INTROSPECTION_MAKEFILE=`$PKG_CONFIG --variable=datadir gobject-introspection-1.0`/gobject-introspection-1.0/Makefile.introspection
+    fi
+    AC_SUBST(INTROSPECTION_SCANNER)
+    AC_SUBST(INTROSPECTION_COMPILER)
+    AC_SUBST(INTROSPECTION_GENERATE)
+    AC_SUBST(INTROSPECTION_GIRDIR)
+    AC_SUBST(INTROSPECTION_TYPELIBDIR)
+    AC_SUBST(INTROSPECTION_CFLAGS)
+    AC_SUBST(INTROSPECTION_LIBS)
+    AC_SUBST(INTROSPECTION_MAKEFILE)
+
+    AM_CONDITIONAL(HAVE_INTROSPECTION, test "x$found_introspection" = "xyes")
+])
+
+
+dnl Usage:
+dnl   GOBJECT_INTROSPECTION_CHECK([minimum-g-i-version])
+
+AC_DEFUN([GOBJECT_INTROSPECTION_CHECK],
+[
+  _GOBJECT_INTROSPECTION_CHECK_INTERNAL([$1])
+])
+
+dnl Usage:
+dnl   GOBJECT_INTROSPECTION_REQUIRE([minimum-g-i-version])
+
+
+AC_DEFUN([GOBJECT_INTROSPECTION_REQUIRE],
+[
+  _GOBJECT_INTROSPECTION_CHECK_INTERNAL([$1], [require])
+])