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# coding=utf-8
# QEMU qapidoc QAPI file parsing extension
# Copyright (c) 2020 Linaro
# This work is licensed under the terms of the GNU GPLv2 or later.
# See the COPYING file in the top-level directory.
qapidoc is a Sphinx extension that implements the qapi-doc directive
The purpose of this extension is to read the documentation comments
in QAPI schema files, and insert them all into the current document.
It implements one new rST directive, "qapi-doc::".
Each qapi-doc:: directive takes one argument, which is the
pathname of the schema file to process, relative to the source tree.
The docs/ file must set the qapidoc_srctree config value to
the root of the QEMU source tree.
The Sphinx documentation on writing extensions is at:
import os
import re
from docutils import nodes
from docutils.statemachine import ViewList
from docutils.parsers.rst import directives, Directive
from sphinx.errors import ExtensionError
from sphinx.util.nodes import nested_parse_with_titles
import sphinx
from qapi.gen import QAPISchemaVisitor
from qapi.error import QAPIError, QAPISemError
from qapi.schema import QAPISchema
# Sphinx up to 1.6 uses AutodocReporter; 1.7 and later
# use switch_source_input. Check borrowed from
Use_SSI = sphinx.__version__[:3] >= '1.7'
if Use_SSI:
from sphinx.util.docutils import switch_source_input
from sphinx.ext.autodoc import AutodocReporter
__version__ = '1.0'
# Function borrowed from pydash, which is under the MIT license
def intersperse(iterable, separator):
"""Yield the members of *iterable* interspersed with *separator*."""
iterable = iter(iterable)
yield next(iterable)
for item in iterable:
yield separator
yield item
class QAPISchemaGenRSTVisitor(QAPISchemaVisitor):
"""A QAPI schema visitor which generates docutils/Sphinx nodes
This class builds up a tree of docutils/Sphinx nodes corresponding
to documentation for the various QAPI objects. To use it, first
create a QAPISchemaGenRSTVisitor object, and call its
visit_begin() method. Then you can call one of the two methods
'freeform' (to add documentation for a freeform documentation
chunk) or 'symbol' (to add documentation for a QAPI symbol). These
will cause the visitor to build up the tree of document
nodes. Once you've added all the documentation via 'freeform' and
'symbol' method calls, you can call 'get_document_nodes' to get
the final list of document nodes (in a form suitable for returning
from a Sphinx directive's 'run' method).
def __init__(self, sphinx_directive):
self._cur_doc = None
self._sphinx_directive = sphinx_directive
self._top_node = nodes.section()
self._active_headings = [self._top_node]
def _make_dlitem(self, term, defn):
"""Return a dlitem node with the specified term and definition.
term should be a list of Text and literal nodes.
defn should be one of:
- a string, which will be handed to _parse_text_into_node
- a list of Text and literal nodes, which will be put into
a paragraph node
dlitem = nodes.definition_list_item()
dlterm = nodes.term('', '', *term)
dlitem += dlterm
if defn:
dldef = nodes.definition()
if isinstance(defn, list):
dldef += nodes.paragraph('', '', *defn)
self._parse_text_into_node(defn, dldef)
dlitem += dldef
return dlitem
def _make_section(self, title):
"""Return a section node with optional title"""
section = nodes.section(ids=[self._sphinx_directive.new_serialno()])
if title:
section += nodes.title(title, title)
return section
def _nodes_for_ifcond(self, ifcond, with_if=True):
"""Return list of Text, literal nodes for the ifcond
Return a list which gives text like ' (If: condition)'.
If with_if is False, we don't return the "(If: " and ")".
doc = ifcond.docgen()
if not doc:
return []
doc = nodes.literal('', doc)
if not with_if:
return [doc]
nodelist = [nodes.Text(' ('), nodes.strong('', 'If: ')]
return nodelist
def _nodes_for_one_member(self, member):
"""Return list of Text, literal nodes for this member
Return a list of doctree nodes which give text like
'name: type (optional) (If: ...)' suitable for use as the
'term' part of a definition list item.
term = [nodes.literal('',]
if member.type.doc_type():
term.append(nodes.Text(': '))
term.append(nodes.literal('', member.type.doc_type()))
if member.optional:
term.append(nodes.Text(' (optional)'))
if member.ifcond.is_present():
return term
def _nodes_for_variant_when(self, variants, variant):
"""Return list of Text, literal nodes for variant 'when' clause
Return a list of doctree nodes which give text like
'when tagname is variant (If: ...)' suitable for use in
the 'variants' part of a definition list.
term = [nodes.Text(' when '),
nodes.Text(' is '),
nodes.literal('', '"%s"' %]
if variant.ifcond.is_present():
return term
def _nodes_for_members(self, doc, what, base=None, variants=None):
"""Return list of doctree nodes for the table of members"""
dlnode = nodes.definition_list()
for section in doc.args.values():
term = self._nodes_for_one_member(section.member)
# TODO drop fallbacks when undocumented members are outlawed
if section.text:
defn = section.text
elif (variants and variants.tag_member == section.member
and not section.member.type.doc_type()):
values = section.member.type.member_names()
defn = [nodes.Text('One of ')]
defn.extend(intersperse([nodes.literal('', v) for v in values],
nodes.Text(', ')))
defn = [nodes.Text('Not documented')]
dlnode += self._make_dlitem(term, defn)
if base:
dlnode += self._make_dlitem([nodes.Text('The members of '),
nodes.literal('', base.doc_type())],
if variants:
for v in variants.variants:
if v.type.is_implicit():
assert not v.type.base and not v.type.variants
for m in v.type.local_members:
term = self._nodes_for_one_member(m)
term.extend(self._nodes_for_variant_when(variants, v))
dlnode += self._make_dlitem(term, None)
term = [nodes.Text('The members of '),
nodes.literal('', v.type.doc_type())]
term.extend(self._nodes_for_variant_when(variants, v))
dlnode += self._make_dlitem(term, None)
if not dlnode.children:
return []
section = self._make_section(what)
section += dlnode
return [section]
def _nodes_for_enum_values(self, doc):
"""Return list of doctree nodes for the table of enum values"""
seen_item = False
dlnode = nodes.definition_list()
for section in doc.args.values():
termtext = [nodes.literal('',]
if section.member.ifcond.is_present():
# TODO drop fallbacks when undocumented members are outlawed
if section.text:
defn = section.text
defn = [nodes.Text('Not documented')]
dlnode += self._make_dlitem(termtext, defn)
seen_item = True
if not seen_item:
return []
section = self._make_section('Values')
section += dlnode
return [section]
def _nodes_for_arguments(self, doc, boxed_arg_type):
"""Return list of doctree nodes for the arguments section"""
if boxed_arg_type:
assert not doc.args
section = self._make_section('Arguments')
dlnode = nodes.definition_list()
dlnode += self._make_dlitem(
[nodes.Text('The members of '),
section += dlnode
return [section]
return self._nodes_for_members(doc, 'Arguments')
def _nodes_for_features(self, doc):
"""Return list of doctree nodes for the table of features"""
seen_item = False
dlnode = nodes.definition_list()
for section in doc.features.values():
dlnode += self._make_dlitem([nodes.literal('',],
seen_item = True
if not seen_item:
return []
section = self._make_section('Features')
section += dlnode
return [section]
def _nodes_for_example(self, exampletext):
"""Return list of doctree nodes for a code example snippet"""
return [nodes.literal_block(exampletext, exampletext)]
def _nodes_for_sections(self, doc):
"""Return list of doctree nodes for additional sections"""
nodelist = []
for section in doc.sections:
snode = self._make_section(
if and'Example'):
snode += self._nodes_for_example(section.text)
self._parse_text_into_node(section.text, snode)
return nodelist
def _nodes_for_if_section(self, ifcond):
"""Return list of doctree nodes for the "If" section"""
nodelist = []
if ifcond.is_present():
snode = self._make_section('If')
snode += nodes.paragraph(
'', '', *self._nodes_for_ifcond(ifcond, with_if=False)
return nodelist
def _add_doc(self, typ, sections):
"""Add documentation for a command/object/enum...
We assume we're documenting the thing defined in self._cur_doc.
typ is the type of thing being added ("Command", "Object", etc)
sections is a list of nodes for sections to add to the definition.
doc = self._cur_doc
snode = nodes.section(ids=[self._sphinx_directive.new_serialno()])
snode += nodes.title('', '', *[nodes.literal(doc.symbol, doc.symbol),
nodes.Text(' (' + typ + ')')])
self._parse_text_into_node(doc.body.text, snode)
for s in sections:
if s is not None:
snode += s
def visit_enum_type(self, name, info, ifcond, features, members, prefix):
doc = self._cur_doc
+ self._nodes_for_features(doc)
+ self._nodes_for_sections(doc)
+ self._nodes_for_if_section(ifcond))
def visit_object_type(self, name, info, ifcond, features,
base, members, variants):
doc = self._cur_doc
if base and base.is_implicit():
base = None
self._nodes_for_members(doc, 'Members', base, variants)
+ self._nodes_for_features(doc)
+ self._nodes_for_sections(doc)
+ self._nodes_for_if_section(ifcond))
def visit_alternate_type(self, name, info, ifcond, features, variants):
doc = self._cur_doc
self._nodes_for_members(doc, 'Members')
+ self._nodes_for_features(doc)
+ self._nodes_for_sections(doc)
+ self._nodes_for_if_section(ifcond))
def visit_command(self, name, info, ifcond, features, arg_type,
ret_type, gen, success_response, boxed, allow_oob,
allow_preconfig, coroutine):
doc = self._cur_doc
arg_type if boxed else None)
+ self._nodes_for_features(doc)
+ self._nodes_for_sections(doc)
+ self._nodes_for_if_section(ifcond))
def visit_event(self, name, info, ifcond, features, arg_type, boxed):
doc = self._cur_doc
arg_type if boxed else None)
+ self._nodes_for_features(doc)
+ self._nodes_for_sections(doc)
+ self._nodes_for_if_section(ifcond))
def symbol(self, doc, entity):
"""Add documentation for one symbol to the document tree
This is the main entry point which causes us to add documentation
nodes for a symbol (which could be a 'command', 'object', 'event',
etc). We do this by calling 'visit' on the schema entity, which
will then call back into one of our visit_* methods, depending
on what kind of thing this symbol is.
self._cur_doc = doc
self._cur_doc = None
def _start_new_heading(self, heading, level):
"""Start a new heading at the specified heading level
Create a new section whose title is 'heading' and which is placed
in the docutils node tree as a child of the most recent level-1
heading. Subsequent document sections (commands, freeform doc chunks,
etc) will be placed as children of this new heading section.
if len(self._active_headings) < level:
raise QAPISemError(,
'Level %d subheading found outside a '
'level %d heading'
% (level, level - 1))
snode = self._make_section(heading)
self._active_headings[level - 1] += snode
self._active_headings = self._active_headings[:level]
def _add_node_to_current_heading(self, node):
"""Add the node to whatever the current active heading is"""
self._active_headings[-1] += node
def freeform(self, doc):
"""Add a piece of 'freeform' documentation to the document tree
A 'freeform' document chunk doesn't relate to any particular
symbol (for instance, it could be an introduction).
If the freeform document starts with a line of the form
'= Heading text', this is a section or subsection heading, with
the heading level indicated by the number of '=' signs.
# QAPIDoc documentation says free-form documentation blocks
# must have only a body section, nothing else.
assert not doc.sections
assert not doc.args
assert not doc.features
self._cur_doc = doc
text = doc.body.text
if re.match(r'=+ ', text):
# Section/subsection heading (if present, will always be
# the first line of the block)
(heading, _, text) = text.partition('\n')
(leader, _, heading) = heading.partition(' ')
self._start_new_heading(heading, len(leader))
if text == '':
node = self._make_section(None)
self._parse_text_into_node(text, node)
self._cur_doc = None
def _parse_text_into_node(self, doctext, node):
"""Parse a chunk of QAPI-doc-format text into the node
The doc comment can contain most inline rST markup, including
bulleted and enumerated lists.
As an extra permitted piece of markup, @var will be turned
into ``var``.
# Handle the "@var means ``var`` case
doctext = re.sub(r'@([\w-]+)', r'``\1``', doctext)
rstlist = ViewList()
for line in doctext.splitlines():
# The reported line number will always be that of the start line
# of the doc comment, rather than the actual location of the error.
# Being more precise would require overhaul of the QAPIDoc class
# to track lines more exactly within all the sub-parts of the doc
# comment, as well as counting lines here.
# Append a blank line -- in some cases rST syntax errors get
# attributed to the line after one with actual text, and if there
# isn't anything in the ViewList corresponding to that then Sphinx
# 1.6's AutodocReporter will then misidentify the source/line location
# in the error message (usually attributing it to the top-level
# .rst file rather than the offending .json file). The extra blank
# line won't affect the rendered output.
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
class QAPISchemaGenDepVisitor(QAPISchemaVisitor):
"""A QAPI schema visitor which adds Sphinx dependencies each module
This class calls the Sphinx note_dependency() function to tell Sphinx
that the generated documentation output depends on the input
schema file associated with each module in the QAPI input.
def __init__(self, env, qapidir):
self._env = env
self._qapidir = qapidir
def visit_module(self, name):
if name != "./builtin":
qapifile = self._qapidir + '/' + name
class QAPIDocDirective(Directive):
"""Extract documentation from the specified QAPI .json file"""
required_argument = 1
optional_arguments = 1
option_spec = {
'qapifile': directives.unchanged_required
has_content = False
def new_serialno(self):
"""Return a unique new ID string suitable for use as a node's ID"""
env = self.state.document.settings.env
return 'qapidoc-%d' % env.new_serialno('qapidoc')
def run(self):
env = self.state.document.settings.env
qapifile = env.config.qapidoc_srctree + '/' + self.arguments[0]
qapidir = os.path.dirname(qapifile)
schema = QAPISchema(qapifile)
# 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)
for doc in
if doc.symbol:
vis.symbol(doc, schema.lookup_entity(doc.symbol))
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))
def do_parse(self, rstlist, node):
"""Parse rST source lines and add them to the specified node
Take the list of rST source lines rstlist, parse them as
rST, and add the resulting docutils nodes as children of node.
The nodes are parsed in a way that allows them to include
subheadings (titles) without confusing the rendering of
anything else.
# This is from -- it works around an API change in
# Sphinx between 1.6 and 1.7. Unlike, we use
# sphinx.util.nodes.nested_parse_with_titles() rather than the
# plain self.state.nested_parse(), and so we can drop the saving
# of title_styles and section_level that does,
# because nested_parse_with_titles() does that for us.
if Use_SSI:
with switch_source_input(self.state, rstlist):
nested_parse_with_titles(self.state, rstlist, node)
save = self.state.memo.reporter
self.state.memo.reporter = AutodocReporter(
rstlist, self.state.memo.reporter)
nested_parse_with_titles(self.state, rstlist, node)
self.state.memo.reporter = save
def setup(app):
""" Register qapi-doc directive with Sphinx"""
app.add_config_value('qapidoc_srctree', None, 'env')
app.add_directive('qapi-doc', QAPIDocDirective)
return dict(