[gtk-doc] configure.ac: check for python3-pygments

[Stefan Sauer <stefkost src gnome org>]

commit 7ac15e6f7b17dfb3715bf3ab09f8ed25f7decbd7
Author: Stefan Sauer <ensonic users sf net>
Date:   Mon Apr 15 18:51:42 2019 +0200

    configure.ac: check for python3-pygments
    
    We now require this for fixxref as well.

 configure.ac           |  5 +++++
 m4/ax_python_module.m4 | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)
---
diff --git a/configure.ac b/configure.ac
index 97608d2..4a5c0ef 100644
--- a/configure.ac
+++ b/configure.ac
@@ -150,6 +150,11 @@ if test "x$have_yelp_tools" != "xyes"; then
 fi
 AM_CONDITIONAL([HAVE_YELP_TOOLS],[test x$have_yelp_tools = xyes])
 
+dnl
+dnl Python modules
+dnl
+AX_PYTHON_MODULE("pygments")
+
 AC_CONFIG_FILES([Makefile
 gtk-doc.pc
 buildsystems/autotools/Makefile
diff --git a/m4/ax_python_module.m4 b/m4/ax_python_module.m4
new file mode 100644
index 0000000..f0f873d
--- /dev/null
+++ b/m4/ax_python_module.m4
@@ -0,0 +1,56 @@
+# ===========================================================================
+#     https://www.gnu.org/software/autoconf-archive/ax_python_module.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_PYTHON_MODULE(modname[, fatal, python])
+#
+# DESCRIPTION
+#
+#   Checks for Python module.
+#
+#   If fatal is non-empty then absence of a module will trigger an error.
+#   The third parameter can either be "python" for Python 2 or "python3" for
+#   Python 3; defaults to Python 3.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Andrew Collier
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 9
+
+AU_ALIAS([AC_PYTHON_MODULE], [AX_PYTHON_MODULE])
+AC_DEFUN([AX_PYTHON_MODULE],[
+    if test -z $PYTHON;
+    then
+        if test -z "$3";
+        then
+            PYTHON="python3"
+        else
+            PYTHON="$3"
+        fi
+    fi
+    PYTHON_NAME=`basename $PYTHON`
+    AC_MSG_CHECKING($PYTHON_NAME module: $1)
+    $PYTHON -c "import $1" 2>/dev/null
+    if test $? -eq 0;
+    then
+        AC_MSG_RESULT(yes)
+        eval AS_TR_CPP(HAVE_PYMOD_$1)=yes
+    else
+        AC_MSG_RESULT(no)
+        eval AS_TR_CPP(HAVE_PYMOD_$1)=no
+        #
+        if test -n "$2"
+        then
+            AC_MSG_ERROR(failed to find required module $1)
+            exit 1
+        fi
+    fi
+])