xref: /openbmc/qemu/docs/sphinx/qapi_domain.py (revision 902c9b0e34049283628c4bd00a6841e13b754fec)
1"""
2QAPI domain extension.
3"""
4
5from __future__ import annotations
6
7from typing import (
8    TYPE_CHECKING,
9    AbstractSet,
10    Any,
11    Dict,
12    Iterable,
13    List,
14    NamedTuple,
15    Optional,
16    Tuple,
17    cast,
18)
19
20from docutils import nodes
21from docutils.parsers.rst import directives
22
23from compat import KeywordNode, SpaceNode
24from sphinx import addnodes
25from sphinx.addnodes import desc_signature, pending_xref
26from sphinx.directives import ObjectDescription
27from sphinx.domains import (
28    Domain,
29    Index,
30    IndexEntry,
31    ObjType,
32)
33from sphinx.locale import _, __
34from sphinx.roles import XRefRole
35from sphinx.util import logging
36from sphinx.util.docfields import Field, GroupedField, TypedField
37from sphinx.util.nodes import make_id, make_refnode
38
39
40if TYPE_CHECKING:
41    from docutils.nodes import Element, Node
42
43    from sphinx.application import Sphinx
44    from sphinx.builders import Builder
45    from sphinx.environment import BuildEnvironment
46    from sphinx.util.typing import OptionSpec
47
48logger = logging.getLogger(__name__)
49
50
51class ObjectEntry(NamedTuple):
52    docname: str
53    node_id: str
54    objtype: str
55    aliased: bool
56
57
58class QAPIXRefRole(XRefRole):
59
60    def process_link(
61        self,
62        env: BuildEnvironment,
63        refnode: Element,
64        has_explicit_title: bool,
65        title: str,
66        target: str,
67    ) -> tuple[str, str]:
68        refnode["qapi:module"] = env.ref_context.get("qapi:module")
69
70        # Cross-references that begin with a tilde adjust the title to
71        # only show the reference without a leading module, even if one
72        # was provided. This is a Sphinx-standard syntax; give it
73        # priority over QAPI-specific type markup below.
74        hide_module = False
75        if target.startswith("~"):
76            hide_module = True
77            target = target[1:]
78
79        # Type names that end with "?" are considered optional
80        # arguments and should be documented as such, but it's not
81        # part of the xref itself.
82        if target.endswith("?"):
83            refnode["qapi:optional"] = True
84            target = target[:-1]
85
86        # Type names wrapped in brackets denote lists. strip the
87        # brackets and remember to add them back later.
88        if target.startswith("[") and target.endswith("]"):
89            refnode["qapi:array"] = True
90            target = target[1:-1]
91
92        if has_explicit_title:
93            # Don't mess with the title at all if it was explicitly set.
94            # Explicit title syntax for references is e.g.
95            # :qapi:type:`target <explicit title>`
96            # and this explicit title overrides everything else here.
97            return title, target
98
99        title = target
100        if hide_module:
101            title = target.split(".")[-1]
102
103        return title, target
104
105
106# Alias for the return of handle_signature(), which is used in several places.
107# (In the Python domain, this is Tuple[str, str] instead.)
108Signature = str
109
110
111class QAPIDescription(ObjectDescription[Signature]):
112    """
113    Generic QAPI description.
114
115    This is meant to be an abstract class, not instantiated
116    directly. This class handles the abstract details of indexing, the
117    TOC, and reference targets for QAPI descriptions.
118    """
119
120    def handle_signature(self, sig: str, signode: desc_signature) -> Signature:
121        # Do nothing. The return value here is the "name" of the entity
122        # being documented; for QAPI, this is the same as the
123        # "signature", which is just a name.
124
125        # Normally this method must also populate signode with nodes to
126        # render the signature; here we do nothing instead - the
127        # subclasses will handle this.
128        return sig
129
130    def get_index_text(self, name: Signature) -> Tuple[str, str]:
131        """Return the text for the index entry of the object."""
132
133        # NB: this is used for the global index, not the QAPI index.
134        return ("single", f"{name} (QMP {self.objtype})")
135
136    def add_target_and_index(
137        self, name: Signature, sig: str, signode: desc_signature
138    ) -> None:
139        # name is the return value of handle_signature.
140        # sig is the original, raw text argument to handle_signature.
141        # For QAPI, these are identical, currently.
142
143        assert self.objtype
144
145        # If we're documenting a module, don't include the module as
146        # part of the FQN.
147        modname = ""
148        if self.objtype != "module":
149            modname = self.options.get(
150                "module", self.env.ref_context.get("qapi:module")
151            )
152        fullname = (modname + "." if modname else "") + name
153
154        node_id = make_id(
155            self.env, self.state.document, self.objtype, fullname
156        )
157        signode["ids"].append(node_id)
158
159        self.state.document.note_explicit_target(signode)
160        domain = cast(QAPIDomain, self.env.get_domain("qapi"))
161        domain.note_object(fullname, self.objtype, node_id, location=signode)
162
163        if "no-index-entry" not in self.options:
164            arity, indextext = self.get_index_text(name)
165            assert self.indexnode is not None
166            if indextext:
167                self.indexnode["entries"].append(
168                    (arity, indextext, node_id, "", None)
169                )
170
171    def _object_hierarchy_parts(
172        self, sig_node: desc_signature
173    ) -> Tuple[str, ...]:
174        if "fullname" not in sig_node:
175            return ()
176        modname = sig_node.get("module")
177        fullname = sig_node["fullname"]
178
179        if modname:
180            return (modname, *fullname.split("."))
181
182        return tuple(fullname.split("."))
183
184    def _toc_entry_name(self, sig_node: desc_signature) -> str:
185        # This controls the name in the TOC and on the sidebar.
186
187        # This is the return type of _object_hierarchy_parts().
188        toc_parts = cast(Tuple[str, ...], sig_node.get("_toc_parts", ()))
189        if not toc_parts:
190            return ""
191
192        config = self.env.app.config
193        *parents, name = toc_parts
194        if config.toc_object_entries_show_parents == "domain":
195            return sig_node.get("fullname", name)
196        if config.toc_object_entries_show_parents == "hide":
197            return name
198        if config.toc_object_entries_show_parents == "all":
199            return ".".join(parents + [name])
200        return ""
201
202
203class QAPIObject(QAPIDescription):
204    """
205    Description of a generic QAPI object.
206
207    It's not used directly, but is instead subclassed by specific directives.
208    """
209
210    # Inherit some standard options from Sphinx's ObjectDescription
211    option_spec: OptionSpec = (  # type:ignore[misc]
212        ObjectDescription.option_spec.copy()
213    )
214    option_spec.update(
215        {
216            # Borrowed from the Python domain:
217            "module": directives.unchanged,  # Override contextual module name
218            # These are QAPI originals:
219            "since": directives.unchanged,
220        }
221    )
222
223    doc_field_types = [
224        # :feat name: descr
225        GroupedField(
226            "feature",
227            label=_("Features"),
228            names=("feat",),
229            can_collapse=False,
230        ),
231    ]
232
233    def get_signature_prefix(self) -> List[nodes.Node]:
234        """Return a prefix to put before the object name in the signature."""
235        assert self.objtype
236        return [
237            KeywordNode("", self.objtype.title()),
238            SpaceNode(" "),
239        ]
240
241    def get_signature_suffix(self) -> List[nodes.Node]:
242        """Return a suffix to put after the object name in the signature."""
243        ret: List[nodes.Node] = []
244
245        if "since" in self.options:
246            ret += [
247                SpaceNode(" "),
248                addnodes.desc_sig_element(
249                    "", f"(Since: {self.options['since']})"
250                ),
251            ]
252
253        return ret
254
255    def handle_signature(self, sig: str, signode: desc_signature) -> Signature:
256        """
257        Transform a QAPI definition name into RST nodes.
258
259        This method was originally intended for handling function
260        signatures. In the QAPI domain, however, we only pass the
261        definition name as the directive argument and handle everything
262        else in the content body with field lists.
263
264        As such, the only argument here is "sig", which is just the QAPI
265        definition name.
266        """
267        modname = self.options.get(
268            "module", self.env.ref_context.get("qapi:module")
269        )
270
271        signode["fullname"] = sig
272        signode["module"] = modname
273        sig_prefix = self.get_signature_prefix()
274        if sig_prefix:
275            signode += addnodes.desc_annotation(
276                str(sig_prefix), "", *sig_prefix
277            )
278        signode += addnodes.desc_name(sig, sig)
279        signode += self.get_signature_suffix()
280
281        return sig
282
283
284class QAPICommand(QAPIObject):
285    """Description of a QAPI Command."""
286
287    doc_field_types = QAPIObject.doc_field_types.copy()
288    doc_field_types.extend(
289        [
290            # :arg TypeName ArgName: descr
291            TypedField(
292                "argument",
293                label=_("Arguments"),
294                names=("arg",),
295                can_collapse=False,
296            ),
297            # :error: descr
298            Field(
299                "error",
300                label=_("Errors"),
301                names=("error", "errors"),
302                has_arg=False,
303            ),
304            # :return TypeName: descr
305            GroupedField(
306                "returnvalue",
307                label=_("Return"),
308                names=("return",),
309                can_collapse=True,
310            ),
311        ]
312    )
313
314
315class QAPIEnum(QAPIObject):
316    """Description of a QAPI Enum."""
317
318    doc_field_types = QAPIObject.doc_field_types.copy()
319    doc_field_types.extend(
320        [
321            # :value name: descr
322            GroupedField(
323                "value",
324                label=_("Values"),
325                names=("value",),
326                can_collapse=False,
327            )
328        ]
329    )
330
331
332class QAPIModule(QAPIDescription):
333    """
334    Directive to mark description of a new module.
335
336    This directive doesn't generate any special formatting, and is just
337    a pass-through for the content body. Named section titles are
338    allowed in the content body.
339
340    Use this directive to create entries for the QAPI module in the
341    global index and the QAPI index; as well as to associate subsequent
342    definitions with the module they are defined in for purposes of
343    search and QAPI index organization.
344
345    :arg: The name of the module.
346    :opt no-index: Don't add cross-reference targets or index entries.
347    :opt no-typesetting: Don't render the content body (but preserve any
348       cross-reference target IDs in the squelched output.)
349
350    Example::
351
352       .. qapi:module:: block-core
353          :no-index:
354          :no-typesetting:
355
356          Lorem ipsum, dolor sit amet ...
357    """
358
359    def run(self) -> List[Node]:
360        modname = self.arguments[0].strip()
361        self.env.ref_context["qapi:module"] = modname
362        ret = super().run()
363
364        # ObjectDescription always creates a visible signature bar. We
365        # want module items to be "invisible", however.
366
367        # Extract the content body of the directive:
368        assert isinstance(ret[-1], addnodes.desc)
369        desc_node = ret.pop(-1)
370        assert isinstance(desc_node.children[1], addnodes.desc_content)
371        ret.extend(desc_node.children[1].children)
372
373        # Re-home node_ids so anchor refs still work:
374        node_ids: List[str]
375        if node_ids := [
376            node_id
377            for el in desc_node.children[0].traverse(nodes.Element)
378            for node_id in cast(List[str], el.get("ids", ()))
379        ]:
380            target_node = nodes.target(ids=node_ids)
381            ret.insert(1, target_node)
382
383        return ret
384
385
386class QAPIIndex(Index):
387    """
388    Index subclass to provide the QAPI definition index.
389    """
390
391    # pylint: disable=too-few-public-methods
392
393    name = "index"
394    localname = _("QAPI Index")
395    shortname = _("QAPI Index")
396
397    def generate(
398        self,
399        docnames: Optional[Iterable[str]] = None,
400    ) -> Tuple[List[Tuple[str, List[IndexEntry]]], bool]:
401        assert isinstance(self.domain, QAPIDomain)
402        content: Dict[str, List[IndexEntry]] = {}
403        collapse = False
404
405        # list of all object (name, ObjectEntry) pairs, sorted by name
406        # (ignoring the module)
407        objects = sorted(
408            self.domain.objects.items(),
409            key=lambda x: x[0].split(".")[-1].lower(),
410        )
411
412        for objname, obj in objects:
413            if docnames and obj.docname not in docnames:
414                continue
415
416            # Strip the module name out:
417            objname = objname.split(".")[-1]
418
419            # Add an alphabetical entry:
420            entries = content.setdefault(objname[0].upper(), [])
421            entries.append(
422                IndexEntry(
423                    objname, 0, obj.docname, obj.node_id, obj.objtype, "", ""
424                )
425            )
426
427            # Add a categorical entry:
428            category = obj.objtype.title() + "s"
429            entries = content.setdefault(category, [])
430            entries.append(
431                IndexEntry(objname, 0, obj.docname, obj.node_id, "", "", "")
432            )
433
434        # alphabetically sort categories; type names first, ABC entries last.
435        sorted_content = sorted(
436            content.items(),
437            key=lambda x: (len(x[0]) == 1, x[0]),
438        )
439        return sorted_content, collapse
440
441
442class QAPIDomain(Domain):
443    """QAPI language domain."""
444
445    name = "qapi"
446    label = "QAPI"
447
448    # This table associates cross-reference object types (key) with an
449    # ObjType instance, which defines the valid cross-reference roles
450    # for each object type.
451    #
452    # e.g., the :qapi:type: cross-reference role can refer to enum,
453    # struct, union, or alternate objects; but :qapi:obj: can refer to
454    # anything. Each object also gets its own targeted cross-reference role.
455    object_types: Dict[str, ObjType] = {
456        "module": ObjType(_("module"), "mod", "any"),
457        "command": ObjType(_("command"), "cmd", "any"),
458        "enum": ObjType(_("enum"), "enum", "type", "any"),
459    }
460
461    # Each of these provides a rST directive,
462    # e.g. .. qapi:module:: block-core
463    directives = {
464        "module": QAPIModule,
465        "command": QAPICommand,
466        "enum": QAPIEnum,
467    }
468
469    # These are all cross-reference roles; e.g.
470    # :qapi:cmd:`query-block`. The keys correlate to the names used in
471    # the object_types table values above.
472    roles = {
473        "mod": QAPIXRefRole(),
474        "cmd": QAPIXRefRole(),
475        "enum": QAPIXRefRole(),
476        # reference any data type (excludes modules, commands, events)
477        "type": QAPIXRefRole(),
478        "any": QAPIXRefRole(),  # reference *any* type of QAPI object.
479    }
480
481    # Moved into the data property at runtime;
482    # this is the internal index of reference-able objects.
483    initial_data: Dict[str, Dict[str, Tuple[Any]]] = {
484        "objects": {},  # fullname -> ObjectEntry
485    }
486
487    # Index pages to generate; each entry is an Index class.
488    indices = [
489        QAPIIndex,
490    ]
491
492    @property
493    def objects(self) -> Dict[str, ObjectEntry]:
494        ret = self.data.setdefault("objects", {})
495        return ret  # type: ignore[no-any-return]
496
497    def note_object(
498        self,
499        name: str,
500        objtype: str,
501        node_id: str,
502        aliased: bool = False,
503        location: Any = None,
504    ) -> None:
505        """Note a QAPI object for cross reference."""
506        if name in self.objects:
507            other = self.objects[name]
508            if other.aliased and aliased is False:
509                # The original definition found. Override it!
510                pass
511            elif other.aliased is False and aliased:
512                # The original definition is already registered.
513                return
514            else:
515                # duplicated
516                logger.warning(
517                    __(
518                        "duplicate object description of %s, "
519                        "other instance in %s, use :no-index: for one of them"
520                    ),
521                    name,
522                    other.docname,
523                    location=location,
524                )
525        self.objects[name] = ObjectEntry(
526            self.env.docname, node_id, objtype, aliased
527        )
528
529    def clear_doc(self, docname: str) -> None:
530        for fullname, obj in list(self.objects.items()):
531            if obj.docname == docname:
532                del self.objects[fullname]
533
534    def merge_domaindata(
535        self, docnames: AbstractSet[str], otherdata: Dict[str, Any]
536    ) -> None:
537        for fullname, obj in otherdata["objects"].items():
538            if obj.docname in docnames:
539                # Sphinx's own python domain doesn't appear to bother to
540                # check for collisions. Assert they don't happen and
541                # we'll fix it if/when the case arises.
542                assert fullname not in self.objects, (
543                    "bug - collision on merge?"
544                    f" {fullname=} {obj=} {self.objects[fullname]=}"
545                )
546                self.objects[fullname] = obj
547
548    def find_obj(
549        self, modname: str, name: str, typ: Optional[str]
550    ) -> list[tuple[str, ObjectEntry]]:
551        """
552        Find a QAPI object for "name", perhaps using the given module.
553
554        Returns a list of (name, object entry) tuples.
555
556        :param modname: The current module context (if any!)
557                        under which we are searching.
558        :param name: The name of the x-ref to resolve;
559                     may or may not include a leading module.
560        :param type: The role name of the x-ref we're resolving, if provided.
561                     (This is absent for "any" lookups.)
562        """
563        if not name:
564            return []
565
566        names: list[str] = []
567        matches: list[tuple[str, ObjectEntry]] = []
568
569        fullname = name
570        if "." in fullname:
571            # We're searching for a fully qualified reference;
572            # ignore the contextual module.
573            pass
574        elif modname:
575            # We're searching for something from somewhere;
576            # try searching the current module first.
577            # e.g. :qapi:cmd:`query-block` or `query-block` is being searched.
578            fullname = f"{modname}.{name}"
579
580        if typ is None:
581            # type isn't specified, this is a generic xref.
582            # search *all* qapi-specific object types.
583            objtypes: List[str] = list(self.object_types)
584        else:
585            # type is specified and will be a role (e.g. obj, mod, cmd)
586            # convert this to eligible object types (e.g. command, module)
587            # using the QAPIDomain.object_types table.
588            objtypes = self.objtypes_for_role(typ, [])
589
590        if name in self.objects and self.objects[name].objtype in objtypes:
591            names = [name]
592        elif (
593            fullname in self.objects
594            and self.objects[fullname].objtype in objtypes
595        ):
596            names = [fullname]
597        else:
598            # exact match wasn't found; e.g. we are searching for
599            # `query-block` from a different (or no) module.
600            searchname = "." + name
601            names = [
602                oname
603                for oname in self.objects
604                if oname.endswith(searchname)
605                and self.objects[oname].objtype in objtypes
606            ]
607
608        matches = [(oname, self.objects[oname]) for oname in names]
609        if len(matches) > 1:
610            matches = [m for m in matches if not m[1].aliased]
611        return matches
612
613    def resolve_xref(
614        self,
615        env: BuildEnvironment,
616        fromdocname: str,
617        builder: Builder,
618        typ: str,
619        target: str,
620        node: pending_xref,
621        contnode: Element,
622    ) -> nodes.reference | None:
623        modname = node.get("qapi:module")
624        matches = self.find_obj(modname, target, typ)
625
626        if not matches:
627            return None
628
629        if len(matches) > 1:
630            logger.warning(
631                __("more than one target found for cross-reference %r: %s"),
632                target,
633                ", ".join(match[0] for match in matches),
634                type="ref",
635                subtype="qapi",
636                location=node,
637            )
638
639        name, obj = matches[0]
640        return make_refnode(
641            builder, fromdocname, obj.docname, obj.node_id, contnode, name
642        )
643
644    def resolve_any_xref(
645        self,
646        env: BuildEnvironment,
647        fromdocname: str,
648        builder: Builder,
649        target: str,
650        node: pending_xref,
651        contnode: Element,
652    ) -> List[Tuple[str, nodes.reference]]:
653        results: List[Tuple[str, nodes.reference]] = []
654        matches = self.find_obj(node.get("qapi:module"), target, None)
655        for name, obj in matches:
656            rolename = self.role_for_objtype(obj.objtype)
657            assert rolename is not None
658            role = f"qapi:{rolename}"
659            refnode = make_refnode(
660                builder, fromdocname, obj.docname, obj.node_id, contnode, name
661            )
662            results.append((role, refnode))
663        return results
664
665
666def setup(app: Sphinx) -> Dict[str, Any]:
667    app.setup_extension("sphinx.directives")
668    app.add_domain(QAPIDomain)
669
670    return {
671        "version": "1.0",
672        "env_version": 1,
673        "parallel_read_safe": True,
674        "parallel_write_safe": True,
675    }
676