[PATCH 06/23] docs/qapidoc: add transmogrifier stub

[John Snow]

This commit adds a stubbed option to the qapi-doc directive that opts-in
to the new rST generator; the implementation of which will follow in
subsequent commits.

Once all QAPI documents have been converted, this option and the old
qapidoc implementation can be dropped.

Note that moving code outside of the try...except block has no impact
because the code moved outside of that block does not ever raise a
QAPIError.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 docs/sphinx/qapidoc.py | 41 ++++++++++++++++++++++++++++-------------
 1 file changed, 28 insertions(+), 13 deletions(-)

diff --git a/docs/sphinx/qapidoc.py b/docs/sphinx/qapidoc.py
index 6abdcc884f5..230e67bca23 100644
--- a/docs/sphinx/qapidoc.py
+++ b/docs/sphinx/qapidoc.py
@@ -452,9 +452,9 @@ def _parse_text_into_node(self, doctext, node):
         rstlist.append("", self._cur_doc.info.fname, self._cur_doc.info.line)
         self._sphinx_directive.do_parse(rstlist, node)
 
-    def get_document_nodes(self):
-        """Return the list of docutils nodes which make up the document"""
-        return self._top_node.children
+    def get_document_node(self):
+        """Return the root docutils node which makes up the document"""
+        return self._top_node
 
 
 # Turn the black formatter on for the rest of the file.
@@ -503,7 +503,10 @@ class QAPIDocDirective(NestedDirective):
 
     required_argument = 1
     optional_arguments = 1
-    option_spec = {"qapifile": directives.unchanged_required}
+    option_spec = {
+        "qapifile": directives.unchanged_required,
+        "transmogrify": directives.flag,
+    }
     has_content = False
 
     def new_serialno(self):
@@ -511,10 +514,24 @@ def new_serialno(self):
         env = self.state.document.settings.env
         return "qapidoc-%d" % env.new_serialno("qapidoc")
 
+    def transmogrify(self, schema) -> nodes.Element:
+        raise NotImplementedError
+
+    def legacy(self, schema) -> nodes.Element:
+        vis = QAPISchemaGenRSTVisitor(self)
+        vis.visit_begin(schema)
+        for doc in schema.docs:
+            if doc.symbol:
+                vis.symbol(doc, schema.lookup_entity(doc.symbol))
+            else:
+                vis.freeform(doc)
+        return vis.get_document_node()
+
     def run(self):
         env = self.state.document.settings.env
         qapifile = env.config.qapidoc_srctree + "/" + self.arguments[0]
         qapidir = os.path.dirname(qapifile)
+        transmogrify = "transmogrify" in self.options
 
         try:
             schema = QAPISchema(qapifile)
@@ -522,20 +539,18 @@ def run(self):
             # First tell Sphinx about all the schema files that the
             # output documentation depends on (including 'qapifile' itself)
             schema.visit(QAPISchemaGenDepVisitor(env, qapidir))
-
-            vis = QAPISchemaGenRSTVisitor(self)
-            vis.visit_begin(schema)
-            for doc in schema.docs:
-                if doc.symbol:
-                    vis.symbol(doc, schema.lookup_entity(doc.symbol))
-                else:
-                    vis.freeform(doc)
-            return vis.get_document_nodes()
         except QAPIError as err:
             # Launder QAPI parse errors into Sphinx extension errors
             # so they are displayed nicely to the user
             raise ExtensionError(str(err)) from err
 
+        if transmogrify:
+            contentnode = self.transmogrify(schema)
+        else:
+            contentnode = self.legacy(schema)
+
+        return contentnode.children
+
 
 class QMPExample(CodeBlock, NestedDirective):
     """
-- 
2.47.0