[PATCH v6 4/9] m4/python: add function to docs_tool.m4 and new m4 module

[Luca Fancellu <luca.fancellu@xxxxxxx>]

Add ax_python_module.m4 to have a way to check if
a python module is installed in the system.

Add a function to docs_tool.m4 to throw an error if the
required docs tool is missing.

Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
 m4/ax_python_module.m4 | 56 ++++++++++++++++++++++++++++++++++++++++++
 m4/docs_tool.m4        |  9 +++++++
 2 files changed, 65 insertions(+)
 create mode 100644 m4/ax_python_module.m4

diff --git a/m4/ax_python_module.m4 b/m4/ax_python_module.m4
new file mode 100644
index 0000000000..107d88264a
--- /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
+])
\ No newline at end of file
diff --git a/m4/docs_tool.m4 b/m4/docs_tool.m4
index 3e8814ac8d..39aa348026 100644
--- a/m4/docs_tool.m4
+++ b/m4/docs_tool.m4
@@ -15,3 +15,12 @@ dnl
         AC_MSG_WARN([$2 is not available so some documentation won't be built])
     ])
 ])
+
+AC_DEFUN([AX_DOCS_TOOL_REQ_PROG], [
+dnl
+    AC_ARG_VAR([$1], [Path to $2 tool])
+    AC_PATH_PROG([$1], [$2])
+    AS_IF([! test -x "$ac_cv_path_$1"], [
+        AC_MSG_ERROR([$2 is needed])
+    ])
+])
\ No newline at end of file
-- 
2.17.1