cpython/Doc/tools/extensions/c_annotations.py

# -*- coding: utf-8 -*-
"""
    c_annotations.py
    ~~~~~~~~~~~~~~~~

    Supports annotations for C API elements:

    * reference count annotations for C API functions.  Based on
      refcount.py and anno-api.py in the old Python documentation tools.

    * stable API annotations

    Usage:
    * Set the `refcount_file` config value to the path to the reference
    count data file.
    * Set the `stable_abi_file` config value to the path to stable ABI list.

    :copyright: Copyright 2007-2014 by Georg Brandl.
    :license: Python license.
"""

from os import path
from docutils import nodes
from docutils.parsers.rst import directives
from docutils.parsers.rst import Directive
from docutils.statemachine import StringList
import csv

from sphinx import addnodes
from sphinx.domains.c import CObject


REST_ROLE_MAP = {
    'function': 'func',
    'var': 'data',
    'type': 'type',
    'macro': 'macro',
    'type': 'type',
    'member': 'member',
}


class RCEntry:
    def __init__(self, name):
        self.name = name
        self.args = []
        self.result_type = ''
        self.result_refs = None


class Annotations:
    def __init__(self, refcount_filename, stable_abi_file):
        self.refcount_data = {}
        with open(refcount_filename, 'r') as fp:
            for line in fp:
                line = line.strip()
                if line[:1] in ("", "#"):
                    # blank lines and comments
                    continue
                parts = line.split(":", 4)
                if len(parts) != 5:
                    raise ValueError("Wrong field count in %r" % line)
                function, type, arg, refcount, comment = parts
                # Get the entry, creating it if needed:
                try:
                    entry = self.refcount_data[function]
                except KeyError:
                    entry = self.refcount_data[function] = RCEntry(function)
                if not refcount or refcount == "null":
                    refcount = None
                else:
                    refcount = int(refcount)
                # Update the entry with the new parameter or the result
                # information.
                if arg:
                    entry.args.append((arg, type, refcount))
                else:
                    entry.result_type = type
                    entry.result_refs = refcount

        self.stable_abi_data = {}
        with open(stable_abi_file, 'r') as fp:
            for record in csv.DictReader(fp):
                role = record['role']
                name = record['name']
                self.stable_abi_data[name] = record

    def add_annotations(self, app, doctree):
        for node in doctree.traverse(addnodes.desc_content):
            par = node.parent
            if par['domain'] != 'c':
                continue
            if not par[0].has_key('ids') or not par[0]['ids']:
                continue
            name = par[0]['ids'][0]
            if name.startswith("c."):
                name = name[2:]

            objtype = par['objtype']

            # Stable ABI annotation. These have two forms:
            #   Part of the [Stable ABI](link).
            #   Part of the [Stable ABI](link) since version X.Y.
            # For structs, there's some more info in the message:
            #   Part of the [Limited API](link) (as an opaque struct).
            #   Part of the [Stable ABI](link) (including all members).
            #   Part of the [Limited API](link) (Only some members are part
            #       of the stable ABI.).
            # ... all of which can have "since version X.Y" appended.
            record = self.stable_abi_data.get(name)
            if record:
                if record['role'] != objtype:
                    raise ValueError(
                        f"Object type mismatch in limited API annotation "
                        f"for {name}: {record['role']!r} != {objtype!r}")
                stable_added = record['added']
                message = ' Part of the '
                emph_node = nodes.emphasis(message, message,
                                           classes=['stableabi'])
                ref_node = addnodes.pending_xref(
                    'Stable ABI', refdomain="std", reftarget='stable',
                    reftype='ref', refexplicit="False")
                struct_abi_kind = record['struct_abi_kind']
                if struct_abi_kind in {'opaque', 'members'}:
                    ref_node += nodes.Text('Limited API')
                else:
                    ref_node += nodes.Text('Stable ABI')
                emph_node += ref_node
                if struct_abi_kind == 'opaque':
                    emph_node += nodes.Text(' (as an opaque struct)')
                elif struct_abi_kind == 'full-abi':
                    emph_node += nodes.Text(' (including all members)')
                if record['ifdef_note']:
                    emph_node += nodes.Text(' ' + record['ifdef_note'])
                if stable_added == '3.2':
                    # Stable ABI was introduced in 3.2.
                    pass
                else:
                    emph_node += nodes.Text(f' since version {stable_added}')
                emph_node += nodes.Text('.')
                if struct_abi_kind == 'members':
                    emph_node += nodes.Text(
                        ' (Only some members are part of the stable ABI.)')
                node.insert(0, emph_node)

            # Unstable API annotation.
            if name.startswith('PyUnstable'):
                warn_node = nodes.admonition(
                    classes=['unstable-c-api', 'warning'])
                message = 'This is '
                emph_node = nodes.emphasis(message, message)
                ref_node = addnodes.pending_xref(
                    'Unstable API', refdomain="std",
                    reftarget='unstable-c-api',
                    reftype='ref', refexplicit="False")
                ref_node += nodes.Text('Unstable API')
                emph_node += ref_node
                emph_node += nodes.Text('. It may change without warning in minor releases.')
                warn_node += emph_node
                node.insert(0, warn_node)

            # Return value annotation
            if objtype != 'function':
                continue
            entry = self.refcount_data.get(name)
            if not entry:
                continue
            elif not entry.result_type.endswith("Object*"):
                continue
            if entry.result_refs is None:
                rc = 'Return value: Always NULL.'
            elif entry.result_refs:
                rc = 'Return value: New reference.'
            else:
                rc = 'Return value: Borrowed reference.'
            node.insert(0, nodes.emphasis(rc, rc, classes=['refcount']))


def init_annotations(app):
    annotations = Annotations(
        path.join(app.srcdir, app.config.refcount_file),
        path.join(app.srcdir, app.config.stable_abi_file),
    )
    app.connect('doctree-read', annotations.add_annotations)

    class LimitedAPIList(Directive):

        has_content = False
        required_arguments = 0
        optional_arguments = 0
        final_argument_whitespace = True

        def run(self):
            content = []
            for record in annotations.stable_abi_data.values():
                role = REST_ROLE_MAP[record['role']]
                name = record['name']
                content.append(f'* :c:{role}:`{name}`')

            pnode = nodes.paragraph()
            self.state.nested_parse(StringList(content), 0, pnode)
            return [pnode]

    app.add_directive('limited-api-list', LimitedAPIList)


def setup(app):
    app.add_config_value('refcount_file', '', True)
    app.add_config_value('stable_abi_file', '', True)
    app.connect('builder-inited', init_annotations)

    # monkey-patch C object...
    CObject.option_spec = {
        'noindex': directives.flag,
        'stableabi': directives.flag,
    }
    old_handle_signature = CObject.handle_signature
    def new_handle_signature(self, sig, signode):
        signode.parent['stableabi'] = 'stableabi' in self.options
        return old_handle_signature(self, sig, signode)
    CObject.handle_signature = new_handle_signature
    return {'version': '1.0', 'parallel_read_safe': True}