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// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
import 'package:analyzer/dart/element/element.dart';
import 'package:collection/collection.dart' show IterableExtension;
import 'package:dartdoc/src/model/feature.dart';
import 'package:dartdoc/src/model/model.dart';
import 'package:dartdoc/src/special_elements.dart';
/// Mixin for subclasses of ModelElement representing Elements that can be
/// inherited from one class to another.
/// We can search the inheritance chain between this instance and
/// [definingEnclosingContainer] in [Inheritable.canonicalEnclosingContainer],
/// for the canonical [Class] closest to where this member was defined. We
/// can then know that when we find [Inheritable.modelElement] inside that [Class]'s
/// namespace, that's the one we should treat as canonical and implementors
/// of this class can use that knowledge to determine canonicalization.
/// We pick the class closest to the [definingEnclosingContainer] so that all
/// children of that class inheriting the same member will point to the same
/// place in the documentation, and we pick a canonical class because that's
/// the one in the public namespace that will be documented.
mixin Inheritable on ContainerMember {
/// True if this [Inheritable] is inherited from a different class.
bool get isInherited;
/// True if this [Inheritable] has a parameter whose type is overridden
/// by a subtype.
bool get isCovariant;
Set<Feature> get features => {
if (isOverride) Feature.overrideFeature,
if (isInherited) Feature.inherited,
if (isCovariant) Feature.covariant,
Library? get canonicalLibrary =>
late final ModelElement? canonicalModelElement = () {
final canonicalEnclosingContainer = this.canonicalEnclosingContainer;
if (canonicalEnclosingContainer == null) {
return null;
return canonicalEnclosingContainer.allCanonicalModelElements
.firstWhereOrNull((m) => == name &&
m is PropertyAccessorElement == this is PropertyAccessorElement);
Container? computeCanonicalEnclosingContainer() {
if (isInherited) {
var searchElement = element.declaration;
// TODO(jcollins-g): generate warning if an inherited element's definition
// is in an intermediate non-canonical class in the inheritance chain?
Container? previous;
Container? previousNonSkippable;
Container? found;
for (var c in inheritance.reversed) {
// Filter out mixins.
if (c.containsElement(searchElement)) {
if ((packageGraph.inheritThrough.contains(previous) &&
c != definingEnclosingContainer) ||
(packageGraph.inheritThrough.contains(c) &&
c == definingEnclosingContainer)) {
return previousNonSkippable!
var canonicalContainer = packageGraph
.findCanonicalModelElementFor(c.element) as Container?;
// TODO(jcollins-g): invert this lookup so traversal is recursive
// starting from the ModelElement.
if (canonicalContainer != null) {
found = canonicalContainer;
previous = c;
if (!packageGraph.inheritThrough.contains(c)) {
previousNonSkippable = c;
// This is still OK because we're never supposed to cloak public
// classes.
if (definingEnclosingContainer.isCanonical &&
definingEnclosingContainer.isPublic) {
assert(definingEnclosingContainer == found);
if (found != null) {
return found;
} else if (definingEnclosingContainer is! Extension) {
// TODO(jcollins-g): factor out extension logic into [Extendable].
return packageGraph.findCanonicalModelElementFor(element.enclosingElement)
as Container?;
return super.computeCanonicalEnclosingContainer();
List<InheritingContainer> get inheritance {
var inheritance = [
...(enclosingElement as InheritingContainer).inheritanceChain,
var object = packageGraph.specialClasses[SpecialClass.object];
assert(definingEnclosingContainer == object ||
// Unless the code explicitly extends dart-core's Object, we won't get
// an entry here. So add it.
if (inheritance.last != object && object != null) {
assert(inheritance.where((e) => e == object).length == 1);
return inheritance;
Inheritable? get overriddenElement;
/// True if this [Inheritable] is overriding a superclass.
late final bool isOverride = () {
// The canonical version of the enclosing element -- not
// [canonicalEnclosingElement], as that is the element enclosing the
// canonical version of this element; two different things. Defaults to the
// enclosing element.
// We use canonical elements here where possible to deal with reexports
// as seen in Flutter.
if (enclosingElement is Extension) {
return false;
final overriddenElement = this.overriddenElement;
if (overriddenElement == null) {
// We have to have an overridden element for it to be possible for this
// element to be an override.
return false;
final enclosingCanonical =
enclosingElement.canonicalModelElement as InheritingContainer?;
// The container in which this element was defined, canonical if available.
final definingCanonical =
definingEnclosingContainer.canonicalModelElement as Container? ??
if (enclosingCanonical != definingCanonical) {
// The defining class and the enclosing class for this element must be the
// same (element is defined here).
return false;
// The canonical version of the element we're overriding, if available.
final overriddenCanonical =
overriddenElement.canonicalModelElement ?? overriddenElement;
// If the overridden element isn't public, we shouldn't be an override in
// most cases. Approximation until #1623 is fixed.
final isOverride = overriddenCanonical.isPublic;
assert(!isOverride || !isInherited);
return isOverride;
late final int overriddenDepth = () {
var depth = 0;
var e = this;
while (e.overriddenElement != null) {
depth += 1;
e = e.overriddenElement!;
return depth;