docs/qapidoc: implement transmogrify() method

This is the true top-level processor for the new transmogrifier;
responsible both for generating the intermediate rST and then running
the nested parse on that generated document to produce the final
docutils tree that is then - very finally - postprocessed by sphinx for
final rendering to HTML &c.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-ID: <20250311034303.75779-55-jsnow@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
[Use the opportunity to move the __version__ assignment to where
PEP 8 wants it]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

docs/sphinx/qapidoc.py

@@ -2,6 +2,7 @@
 #
 # QEMU qapidoc QAPI file parsing extension
 #
+# Copyright (c) 2024-2025 Red Hat
 # Copyright (c) 2020 Linaro
 #
 # This work is licensed under the terms of the GNU GPLv2 or later.
@@ -26,6 +27,8 @@ https://www.sphinx-doc.org/en/master/development/index.html
 
 from __future__ import annotations
 
+__version__ = "2.0"
+
 from contextlib import contextmanager
 import os
 from pathlib import Path
@@ -56,6 +59,7 @@ from qapidoc_legacy import QAPISchemaGenRSTVisitor  # type: ignore
 from sphinx import addnodes
 from sphinx.directives.code import CodeBlock
 from sphinx.errors import ExtensionError
+from sphinx.util import logging
 from sphinx.util.docutils import switch_source_input
 from sphinx.util.nodes import nested_parse_with_titles
 
@@ -74,7 +78,7 @@ if TYPE_CHECKING:
     from sphinx.util.typing import ExtensionMetadata
 
 
-__version__ = "1.0"
+logger = logging.getLogger(__name__)
 
 
 class Transmogrifier:
@@ -95,6 +99,10 @@ class Transmogrifier:
         self._result = StringList()
         self.indent = 0
 
+    @property
+    def result(self) -> StringList:
+        return self._result
+
     @property
     def entity(self) -> QAPISchemaDefinition:
         assert self._curr_ent is not None
@@ -438,7 +446,43 @@ class QAPIDocDirective(NestedDirective):
         return "qapidoc-%d" % env.new_serialno("qapidoc")
 
     def transmogrify(self, schema: QAPISchema) -> nodes.Element:
-        raise NotImplementedError
+        logger.info("Transmogrifying QAPI to rST ...")
+        vis = Transmogrifier()
+        modules = set()
+
+        for doc in schema.docs:
+            module_source = doc.info.fname
+            if module_source not in modules:
+                vis.visit_module(module_source)
+                modules.add(module_source)
+
+            if doc.symbol:
+                ent = schema.lookup_entity(doc.symbol)
+                assert isinstance(ent, QAPISchemaDefinition)
+                vis.visit_entity(ent)
+            else:
+                vis.visit_freeform(doc)
+
+        logger.info("Transmogrification complete.")
+
+        contentnode = nodes.section()
+        content = vis.result
+        titles_allowed = True
+
+        logger.info("Transmogrifier running nested parse ...")
+        with switch_source_input(self.state, content):
+            if titles_allowed:
+                node: nodes.Element = nodes.section()
+                node.document = self.state.document
+                nested_parse_with_titles(self.state, content, contentnode)
+            else:
+                node = nodes.paragraph()
+                node.document = self.state.document
+                self.state.nested_parse(content, 0, contentnode)
+        logger.info("Transmogrifier's nested parse completed.")
+        sys.stdout.flush()
+
+        return contentnode
 
     def legacy(self, schema: QAPISchema) -> nodes.Element:
         vis = QAPISchemaGenRSTVisitor(self)
@@ -572,6 +616,7 @@ class QMPExample(CodeBlock, NestedDirective):
 
 def setup(app: Sphinx) -> ExtensionMetadata:
     """Register qapi-doc directive with Sphinx"""
+    app.setup_extension("qapi_domain")
     app.add_config_value("qapidoc_srctree", None, "env")
     app.add_directive("qapi-doc", QAPIDocDirective)
     app.add_directive("qmp-example", QMPExample)