[gobject-introspection/gnome-3-30] docwriter: Support markdown 3.x. Fixes #250

[Christoph Reiter <creiter src gnome org>]

commit 74c506e7c0b04c9aac242afc08cd6731bea5992a
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Wed Dec 19 22:17:16 2018 +0100

    docwriter: Support markdown 3.x. Fixes #250

 giscanner/docwriter.py | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)
---
diff --git a/giscanner/docwriter.py b/giscanner/docwriter.py
index a29ba374..dae2ca9e 100644
--- a/giscanner/docwriter.py
+++ b/giscanner/docwriter.py
@@ -34,7 +34,6 @@ import tempfile
 from xml.sax import saxutils
 from mako.lookup import TemplateLookup
 import markdown
-from markdown.extensions.headerid import HeaderIdExtension
 
 from . import ast, xmlwriter
 from .utils import to_underscores
@@ -66,6 +65,18 @@ language_mimes = {
 }
 
 
+def get_headerid_ext():
+    try:
+        from markdown.extensions.headerid import HeaderIdExtension
+    except ImportError:
+        # markdown 3.x
+        from markdown.extensions.toc import TocExtension
+        return TocExtension(toc_depth=0)
+    else:
+        # markdown 2.x
+        return HeaderIdExtension(forceid=False)
+
+
 def make_page_id(node, recursive=False):
     if isinstance(node, ast.Namespace):
         if recursive:
@@ -1175,7 +1186,7 @@ class DevDocsFormatterGjs(DocFormatterGjs):
             'markdown.extensions.fenced_code',
             'markdown.extensions.nl2br',
             'markdown.extensions.attr_list',
-            HeaderIdExtension(forceid=False)
+            get_headerid_ext(),
         ])
 
     def format_function_name(self, func):
@@ -1263,7 +1274,7 @@ class DevDocsFormatterGjs(DocFormatterGjs):
             'markdown.extensions.fenced_code',
             'markdown.extensions.nl2br',
             'markdown.extensions.attr_list',
-            HeaderIdExtension(forceid=False)
+            get_headerid_ext(),
         ])
 
     def format_in_parameters(self, node):