inheritance_diagram.py

r"""Defines a docutils directive for inserting inheritance diagrams.

Provide the directive with one or more classes or modules (separated
by whitespace).  For modules, all of the classes in that module will
be used.

Example::

   Given the following classes:

   class A: pass
   class B(A): pass
   class C(A): pass
   class D(B, C): pass
   class E(B): pass

   .. inheritance-diagram: D E

   Produces a graph like the following:

               A
              / \
             B   C
            / \ /
           E   D

The graph is inserted as a PNG+image map into HTML and a PDF in
LaTeX.
"""

from __future__ import annotations

import builtins
import hashlib
import inspect
import re
from collections.abc import Iterable
from importlib import import_module
from typing import Any, cast

from docutils import nodes
from docutils.nodes import Node
from docutils.parsers.rst import directives

import sphinx
from sphinx import addnodes
from sphinx.application import Sphinx
from sphinx.environment import BuildEnvironment
from sphinx.ext.graphviz import (
    figure_wrapper,
    graphviz,
    render_dot_html,
    render_dot_latex,
    render_dot_texinfo,
)
from sphinx.util.docutils import SphinxDirective
from sphinx.util.typing import OptionSpec
from sphinx.writers.html import HTML5Translator
from sphinx.writers.latex import LaTeXTranslator
from sphinx.writers.texinfo import TexinfoTranslator

module_sig_re = re.compile(r'''^(?:([\w.]*)\.)?  # module names
                           (\w+)  \s* $          # class/final module name
                           ''', re.VERBOSE)


py_builtins = [obj for obj in vars(builtins).values()
               if inspect.isclass(obj)]


def try_import(objname: str) -> Any:
    """Import a object or module using *name* and *currentmodule*.
    *name* should be a relative name from *currentmodule* or
    a fully-qualified name.

    Returns imported object or module.  If failed, returns None value.
    """
    try:
        return import_module(objname)
    except TypeError:
        # Relative import
        return None
    except ImportError:
        matched = module_sig_re.match(objname)

        if not matched:
            return None

        modname, attrname = matched.groups()

        if modname is None:
            return None
        try:
            module = import_module(modname)
            return getattr(module, attrname, None)
        except ImportError:
            return None


def import_classes(name: str, currmodule: str) -> Any:
    """Import a class using its fully-qualified *name*."""
    target = None

    # import class or module using currmodule
    if currmodule:
        target = try_import(currmodule + '.' + name)

    # import class or module without currmodule
    if target is None:
        target = try_import(name)

    if target is None:
        raise InheritanceException(
            'Could not import class or module %r specified for '
            'inheritance diagram' % name)

    if inspect.isclass(target):
        # If imported object is a class, just return it
        return [target]
    elif inspect.ismodule(target):
        # If imported object is a module, return classes defined on it
        classes = []
        for cls in target.__dict__.values():
            if inspect.isclass(cls) and cls.__module__ == target.__name__:
                classes.append(cls)
        return classes
    raise InheritanceException('%r specified for inheritance diagram is '
                               'not a class or module' % name)


class InheritanceException(Exception):
    pass


class InheritanceGraph:
    """
    Given a list of classes, determines the set of classes that they inherit
    from all the way to the root "object", and then is able to generate a
    graphviz dot graph from them.
    """
    def __init__(self, class_names: list[str], currmodule: str, show_builtins: bool = False,
                 private_bases: bool = False, parts: int = 0,
                 aliases: dict[str, str] | None = None, top_classes: list[Any] = [],
                 ) -> None:
        """*class_names* is a list of child classes to show bases from.

        If *show_builtins* is True, then Python builtins will be shown
        in the graph.
        """
        self.class_names = class_names
        classes = self._import_classes(class_names, currmodule)
        self.class_info = self._class_info(classes, show_builtins,
                                           private_bases, parts, aliases, top_classes)
        if not self.class_info:
            raise InheritanceException('No classes found for '
                                       'inheritance diagram')

    def _import_classes(self, class_names: list[str], currmodule: str) -> list[Any]:
        """Import a list of classes."""
        classes: list[Any] = []
        for name in class_names:
            classes.extend(import_classes(name, currmodule))
        return classes

    def _class_info(self, classes: list[Any], show_builtins: bool, private_bases: bool,
                    parts: int, aliases: dict[str, str], top_classes: list[Any],
                    ) -> list[tuple[str, str, list[str], str]]:
        """Return name and bases for all classes that are ancestors of
        *classes*.

        *parts* gives the number of dotted name parts to include in the
        displayed node names, from right to left. If given as a negative, the
        number of parts to drop from the left. A value of 0 displays the full
        dotted name. E.g. ``sphinx.ext.inheritance_diagram.InheritanceGraph``
        with ``parts=2`` or ``parts=-2`` gets displayed as
        ``inheritance_diagram.InheritanceGraph``, and as
        ``ext.inheritance_diagram.InheritanceGraph`` with ``parts=3`` or
        ``parts=-1``.

        *top_classes* gives the name(s) of the top most ancestor class to
        traverse to. Multiple names can be specified separated by comma.
        """
        all_classes = {}

        def recurse(cls: Any) -> None:
            if not show_builtins and cls in py_builtins:
                return
            if not private_bases and cls.__name__.startswith('_'):
                return

            nodename = self.class_name(cls, parts, aliases)
            fullname = self.class_name(cls, 0, aliases)

            # Use first line of docstring as tooltip, if available
            tooltip = None
            try:
                if cls.__doc__:
                    doc = cls.__doc__.strip().split("\n")[0]
                    if doc:
                        tooltip = '"%s"' % doc.replace('"', '\\"')
            except Exception:  # might raise AttributeError for strange classes
                pass

            baselist: list[str] = []
            all_classes[cls] = (nodename, fullname, baselist, tooltip)

            if fullname in top_classes:
                return

            for base in cls.__bases__:
                if not show_builtins and base in py_builtins:
                    continue
                if not private_bases and base.__name__.startswith('_'):
                    continue
                baselist.append(self.class_name(base, parts, aliases))
                if base not in all_classes:
                    recurse(base)

        for cls in classes:
            recurse(cls)

        return list(all_classes.values())

    def class_name(
        self, cls: Any, parts: int = 0, aliases: dict[str, str] | None = None,
    ) -> str:
        """Given a class object, return a fully-qualified name.

        This works for things I've tested in matplotlib so far, but may not be
        completely general.
        """
        module = cls.__module__
        if module in ('__builtin__', 'builtins'):
            fullname = cls.__name__
        else:
            fullname = f'{module}.{cls.__qualname__}'
        if parts == 0:
            result = fullname
        else:
            name_parts = fullname.split('.')
            result = '.'.join(name_parts[-parts:])
        if aliases is not None and result in aliases:
            return aliases[result]
        return result

    def get_all_class_names(self) -> list[str]:
        """Get all of the class names involved in the graph."""
        return [fullname for (_, fullname, _, _) in self.class_info]

    # These are the default attrs for graphviz
    default_graph_attrs = {
        'rankdir': 'LR',
        'size': '"8.0, 12.0"',
        'bgcolor': 'transparent',
    }
    default_node_attrs = {
        'shape': 'box',
        'fontsize': 10,
        'height': 0.25,
        'fontname': '"Vera Sans, DejaVu Sans, Liberation Sans, '
                    'Arial, Helvetica, sans"',
        'style': '"setlinewidth(0.5),filled"',
        'fillcolor': 'white',
    }
    default_edge_attrs = {
        'arrowsize': 0.5,
        'style': '"setlinewidth(0.5)"',
    }

    def _format_node_attrs(self, attrs: dict[str, Any]) -> str:
        return ','.join(['%s=%s' % x for x in sorted(attrs.items())])

    def _format_graph_attrs(self, attrs: dict[str, Any]) -> str:
        return ''.join(['%s=%s;\n' % x for x in sorted(attrs.items())])

    def generate_dot(self, name: str, urls: dict[str, str] = {},
                     env: BuildEnvironment | None = None,
                     graph_attrs: dict = {}, node_attrs: dict = {}, edge_attrs: dict = {},
                     ) -> str:
        """Generate a graphviz dot graph from the classes that were passed in
        to __init__.

        *name* is the name of the graph.

        *urls* is a dictionary mapping class names to HTTP URLs.

        *graph_attrs*, *node_attrs*, *edge_attrs* are dictionaries containing
        key/value pairs to pass on as graphviz properties.
        """
        g_attrs = self.default_graph_attrs.copy()
        n_attrs = self.default_node_attrs.copy()
        e_attrs = self.default_edge_attrs.copy()
        g_attrs.update(graph_attrs)
        n_attrs.update(node_attrs)
        e_attrs.update(edge_attrs)
        if env:
            g_attrs.update(env.config.inheritance_graph_attrs)
            n_attrs.update(env.config.inheritance_node_attrs)
            e_attrs.update(env.config.inheritance_edge_attrs)

        res: list[str] = []
        res.append('digraph %s {\n' % name)
        res.append(self._format_graph_attrs(g_attrs))

        for name, fullname, bases, tooltip in sorted(self.class_info):
            # Write the node
            this_node_attrs = n_attrs.copy()
            if fullname in urls:
                this_node_attrs['URL'] = '"%s"' % urls[fullname]
                this_node_attrs['target'] = '"_top"'
            if tooltip:
                this_node_attrs['tooltip'] = tooltip
            res.append('  "%s" [%s];\n' %
                       (name, self._format_node_attrs(this_node_attrs)))

            # Write the edges
            for base_name in bases:
                res.append('  "%s" -> "%s" [%s];\n' %
                           (base_name, name,
                            self._format_node_attrs(e_attrs)))
        res.append('}\n')
        return ''.join(res)


class inheritance_diagram(graphviz):
    """
    A docutils node to use as a placeholder for the inheritance diagram.
    """
    pass


class InheritanceDiagram(SphinxDirective):
    """
    Run when the inheritance_diagram directive is first encountered.
    """
    has_content = False
    required_arguments = 1
    optional_arguments = 0
    final_argument_whitespace = True
    option_spec: OptionSpec = {
        'parts': int,
        'private-bases': directives.flag,
        'caption': directives.unchanged,
        'top-classes': directives.unchanged_required,
    }

    def run(self) -> list[Node]:
        node = inheritance_diagram()
        node.document = self.state.document
        class_names = self.arguments[0].split()
        class_role = self.env.get_domain('py').role('class')
        # Store the original content for use as a hash
        node['parts'] = self.options.get('parts', 0)
        node['content'] = ', '.join(class_names)
        node['top-classes'] = []
        for cls in self.options.get('top-classes', '').split(','):
            cls = cls.strip()
            if cls:
                node['top-classes'].append(cls)

        # Create a graph starting with the list of classes
        try:
            graph = InheritanceGraph(
                class_names, self.env.ref_context.get('py:module'),
                parts=node['parts'],
                private_bases='private-bases' in self.options,
                aliases=self.config.inheritance_alias,
                top_classes=node['top-classes'])
        except InheritanceException as err:
            return [node.document.reporter.warning(err, line=self.lineno)]

        # Create xref nodes for each target of the graph's image map and
        # add them to the doc tree so that Sphinx can resolve the
        # references to real URLs later.  These nodes will eventually be
        # removed from the doctree after we're done with them.
        for name in graph.get_all_class_names():
            refnodes, x = class_role(  # type: ignore
                'class', ':class:`%s`' % name, name, 0, self.state)  # type: ignore
            node.extend(refnodes)
        # Store the graph object so we can use it to generate the
        # dot file later
        node['graph'] = graph

        if 'caption' not in self.options:
            self.add_name(node)
            return [node]
        else:
            figure = figure_wrapper(self, node, self.options['caption'])
            self.add_name(figure)
            return [figure]


def get_graph_hash(node: inheritance_diagram) -> str:
    encoded = (node['content'] + str(node['parts'])).encode()
    return hashlib.md5(encoded, usedforsecurity=False).hexdigest()[-10:]


def html_visit_inheritance_diagram(self: HTML5Translator, node: inheritance_diagram) -> None:
    """
    Output the graph for HTML.  This will insert a PNG with clickable
    image map.
    """
    graph = node['graph']

    graph_hash = get_graph_hash(node)
    name = 'inheritance%s' % graph_hash

    # Create a mapping from fully-qualified class names to URLs.
    graphviz_output_format = self.builder.env.config.graphviz_output_format.upper()
    current_filename = self.builder.current_docname + self.builder.out_suffix
    urls = {}
    pending_xrefs = cast(Iterable[addnodes.pending_xref], node)
    for child in pending_xrefs:
        if child.get('refuri') is not None:
            if graphviz_output_format == 'SVG':
                urls[child['reftitle']] = "../" + child.get('refuri')
            else:
                urls[child['reftitle']] = child.get('refuri')
        elif child.get('refid') is not None:
            if graphviz_output_format == 'SVG':
                urls[child['reftitle']] = '../' + current_filename + '#' + child.get('refid')
            else:
                urls[child['reftitle']] = '#' + child.get('refid')

    dotcode = graph.generate_dot(name, urls, env=self.builder.env)
    render_dot_html(self, node, dotcode, {}, 'inheritance', 'inheritance',
                    alt='Inheritance diagram of ' + node['content'])
    raise nodes.SkipNode


def latex_visit_inheritance_diagram(self: LaTeXTranslator, node: inheritance_diagram) -> None:
    """
    Output the graph for LaTeX.  This will insert a PDF.
    """
    graph = node['graph']

    graph_hash = get_graph_hash(node)
    name = 'inheritance%s' % graph_hash

    dotcode = graph.generate_dot(name, env=self.builder.env,
                                 graph_attrs={'size': '"6.0,6.0"'})
    render_dot_latex(self, node, dotcode, {}, 'inheritance')
    raise nodes.SkipNode


def texinfo_visit_inheritance_diagram(self: TexinfoTranslator, node: inheritance_diagram,
                                      ) -> None:
    """
    Output the graph for Texinfo.  This will insert a PNG.
    """
    graph = node['graph']

    graph_hash = get_graph_hash(node)
    name = 'inheritance%s' % graph_hash

    dotcode = graph.generate_dot(name, env=self.builder.env,
                                 graph_attrs={'size': '"6.0,6.0"'})
    render_dot_texinfo(self, node, dotcode, {}, 'inheritance')
    raise nodes.SkipNode


def skip(self: nodes.NodeVisitor, node: inheritance_diagram) -> None:
    raise nodes.SkipNode


def setup(app: Sphinx) -> dict[str, Any]:
    app.setup_extension('sphinx.ext.graphviz')
    app.add_node(
        inheritance_diagram,
        latex=(latex_visit_inheritance_diagram, None),
        html=(html_visit_inheritance_diagram, None),
        text=(skip, None),
        man=(skip, None),
        texinfo=(texinfo_visit_inheritance_diagram, None))
    app.add_directive('inheritance-diagram', InheritanceDiagram)
    app.add_config_value('inheritance_graph_attrs', {}, False)
    app.add_config_value('inheritance_node_attrs', {}, False)
    app.add_config_value('inheritance_edge_attrs', {}, False)
    app.add_config_value('inheritance_alias', {}, False)
    return {'version': sphinx.__display_version__, 'parallel_read_safe': True}