[PATCH] Documentation: implement linkgit macro for Asciidoctor

["brian m. carlson" <sandals@crustytoothpaste.net>]

AsciiDoc uses a configuration file to implement macros like linkgit,
while Asciidoctor uses Ruby extensions.  Implement a Ruby extension that
implements the linkgit macro for Asciidoctor in the same way that
asciidoc.conf does for AsciiDoc.  Adjust the Makefile to use it by
default.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 Documentation/Makefile                  |  5 +----
 Documentation/asciidoctor-extensions.rb | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/asciidoctor-extensions.rb

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 19c42eb60..d1b7a6865 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -179,10 +179,7 @@ ASCIIDOC = asciidoctor
 ASCIIDOC_CONF =
 ASCIIDOC_HTML = xhtml5
 ASCIIDOC_DOCBOOK = docbook45
-ifdef ASCIIDOCTOR_EXTENSIONS_LAB
-ASCIIDOC_EXTRA = -I$(ASCIIDOCTOR_EXTENSIONS_LAB) -rasciidoctor/extensions -rman-inline-macro
-endif
-ASCIIDOC_EXTRA += -alitdd='&\#x2d;&\#x2d;'
+ASCIIDOC_EXTRA += -I. -rasciidoctor-extensions -alitdd='&\#x2d;&\#x2d;'
 DBLATEX_COMMON =
 endif
 
diff --git a/Documentation/asciidoctor-extensions.rb b/Documentation/asciidoctor-extensions.rb
new file mode 100644
index 000000000..09f7088ee
--- /dev/null
+++ b/Documentation/asciidoctor-extensions.rb
@@ -0,0 +1,28 @@
+require 'asciidoctor'
+require 'asciidoctor/extensions'
+
+module Git
+  module Documentation
+    class LinkGitProcessor < Asciidoctor::Extensions::InlineMacroProcessor
+      use_dsl
+
+      named :chrome
+
+      def process(parent, target, attrs)
+        if parent.document.basebackend? 'html'
+          prefix = parent.document.attr('git-relative-html-prefix')
+          %(<a href="#{prefix}#{target}.html">#{target}(#{attrs[1]})</a>\n)
+        elsif parent.document.basebackend? 'docbook'
+          %(<citerefentry>
+<refentrytitle>#{target}</refentrytitle><manvolnum>#{attrs[1]}</manvolnum>
+</citerefentry>
+)
+        end
+      end
+    end
+  end
+end
+
+Asciidoctor::Extensions.register do
+  inline_macro Git::Documentation::LinkGitProcessor, :linkgit
+end
-- 
2.11.0