mirror of
https://github.com/dart-lang/sdk
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0b2e8b4bb1
BUG= https://github.com/dart-lang/sdk/issues/23601 R=kevmoo@google.com Review URL: https://codereview.chromium.org/1401063004 .
96 lines
3.2 KiB
Dart
96 lines
3.2 KiB
Dart
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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part of dart.core;
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/**
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* The base class for all Dart objects.
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*
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* Because Object is the root of the Dart class hierarchy,
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* every other Dart class is a subclass of Object.
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*
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* When you define a class, you should override [toString]
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* to return a string describing an instance of that class.
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* You might also need to define [hashCode] and [==], as described in the
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* [Implementing map
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* keys](https://www.dartlang.org/docs/dart-up-and-running/ch03.html#implementing-map-keys)
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* section of the [library
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* tour](http://www.dartlang.org/docs/dart-up-and-running/contents/ch03.html).
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*/
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class Object {
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/**
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* Creates a new [Object] instance.
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*
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* [Object] instances have no meaningful state, and are only useful
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* through their identity. An [Object] instance is equal to itself
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* only.
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*/
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const Object();
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/**
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* The equality operator.
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*
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* The default behavior for all [Object]s is to return true if and
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* only if [:this:] and [other] are the same object.
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*
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* Override this method to specify a different equality relation on
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* a class. The overriding method must still be an equivalence relation.
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* That is, it must be:
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*
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* * Total: It must return a boolean for all arguments. It should never throw
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* or return `null`.
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*
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* * Reflexive: For all objects `o`, `o == o` must be true.
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*
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* * Symmetric: For all objects `o1` and `o2`, `o1 == o2` and `o2 == o1` must
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* either both be true, or both be false.
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*
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* * Transitive: For all objects `o1`, `o2`, and `o3`, if `o1 == o2` and
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* `o2 == o3` are true, then `o1 == o3` must be true.
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*
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* The method should also be consistent over time, so equality of two objects
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* should not change over time, or at least only change if one of the objects
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* was modified.
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*
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* If a subclass overrides the equality operator it should override
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* the [hashCode] method as well to maintain consistency.
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*/
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bool operator ==(other) => identical(this, other);
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/**
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* Get a hash code for this object.
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*
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* All objects have hash codes. Hash codes are guaranteed to be the
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* same for objects that are equal when compared using the equality
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* operator [:==:]. Other than that there are no guarantees about
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* the hash codes. They will not be consistent between runs and
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* there are no distribution guarantees.
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*
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* If a subclass overrides [hashCode] it should override the
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* equality operator as well to maintain consistency.
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*/
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external int get hashCode;
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/**
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* Returns a string representation of this object.
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*/
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external String toString();
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/**
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* Invoked when a non-existent method or property is accessed.
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*
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* Classes can override [noSuchMethod] to provide custom behavior.
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*
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* If a value is returned, it becomes the result of the original invocation.
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*
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* The default behavior is to throw a [NoSuchMethodError].
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*/
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external dynamic noSuchMethod(Invocation invocation);
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/**
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* A representation of the runtime type of the object.
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*/
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external Type get runtimeType;
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}
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