sdk/lib/core/object.dart - sdk.git - Git at Google

 // Copyright (c) 2012, 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.

 part of dart.core;

 /// The base class for all Dart objects except `null`.
 ///
 /// Because `Object` is a root of the non-nullable Dart class hierarchy,
 /// every other non-`Null` Dart class is a subclass of `Object`.
 ///
 /// When you define a class, you should consider overriding [toString]
 /// to return a string describing an instance of that class.
 /// You might also need to define [hashCode] and [operator ==], as described in the
 /// [Implementing map keys](https://dart.dev/guides/libraries/library-tour#implementing-map-keys)
 /// section of the [library tour](https://dart.dev/guides/libraries/library-tour).
 @pragma("vm:entry-point")
 class Object {
   /// Creates a new [Object] instance.
   ///
   /// [Object] instances have no meaningful state, and are only useful
   /// through their identity. An [Object] instance is equal to itself
   /// only.
   @pragma("vm:recognized", "other")
   const Object();

   /// The equality operator.
   ///
   /// The default behavior for all [Object]s is to return true if and
   /// only if this object and [other] are the same object.
   ///
   /// Override this method to specify a different equality relation on
   /// a class. The overriding method must still be an equivalence relation.
   /// That is, it must be:
   ///
   ///  * Total: It must return a boolean for all arguments. It should never throw.
   ///
   ///  * Reflexive: For all objects `o`, `o == o` must be true.
   ///
   ///  * Symmetric: For all objects `o1` and `o2`, `o1 == o2` and `o2 == o1` must
   ///    either both be true, or both be false.
   ///
   ///  * Transitive: For all objects `o1`, `o2`, and `o3`, if `o1 == o2` and
   ///    `o2 == o3` are true, then `o1 == o3` must be true.
   ///
   /// The method should also be consistent over time,
   /// so whether two objects are equal should only change
   /// if at least one of the objects was modified.
   ///
   /// If a subclass overrides the equality operator, it should override
   /// the [hashCode] method as well to maintain consistency.
   external bool operator ==(Object other);

   /// The hash code for this object.
   ///
   /// A hash code is a single integer which represents the state of the object
   /// that affects [operator ==] comparisons.
   ///
   /// All objects have hash codes.
   /// The default hash code implemented by [Object]
   /// represents only the identity of the object,
   /// the same way as the default [operator ==] implementation only considers objects
   /// equal if they are identical (see [identityHashCode]).
   ///
   /// If [operator ==] is overridden to use the object state instead,
   /// the hash code must also be changed to represent that state,
   /// otherwise the object cannot be used in hash based data structures
   /// like the default [Set] and [Map] implementations.
   ///
   /// Hash codes must be the same for objects that are equal to each other
   /// according to [operator ==].
   /// The hash code of an object should only change if the object changes
   /// in a way that affects equality.
   /// There are no further requirements for the hash codes.
   /// They need not be consistent between executions of the same program
   /// and there are no distribution guarantees.
   ///
   /// Objects that are not equal are allowed to have the same hash code.
   /// It is even technically allowed that all instances have the same hash code,
   /// but if clashes happen too often,
   /// it may reduce the efficiency of hash-based data structures
   /// like [HashSet] or [HashMap].
   ///
   /// If a subclass overrides [hashCode], it should override the
   /// [operator ==] operator as well to maintain consistency.
   external int get hashCode;

   /// A string representation of this object.
   ///
   /// Some classes have a default textual representation,
   /// often paired with a static `parse` function (like [int.parse]).
   /// These classes will provide the textual representation as
   /// their string representation.
   ///
   /// Other classes have no meaningful textual representation
   /// that a program will care about.
   /// Such classes will typically override `toString` to provide
   /// useful information when inspecting the object,
   /// mainly for debugging or logging.
   external String toString();

   /// Invoked when a non-existent method or property is accessed.
   ///
   /// A dynamic member invocation can attempt to call a member which
   /// doesn't exist on the receiving object. Example:
   /// ```dart
   /// dynamic object = 1;
   /// object.add(42); // Statically allowed, run-time error
   /// ```
   /// This invalid code will invoke the `noSuchMethod` method
   /// of the integer `1` with an [Invocation] representing the
   /// `.add(42)` call and arguments (which then throws).
   ///
   /// Classes can override [noSuchMethod] to provide custom behavior
   /// for such invalid dynamic invocations.
   ///
   /// A class with a non-default [noSuchMethod] invocation can also
   /// omit implementations for members of its interface.
   /// Example:
   /// ```dart
   /// class MockList<T> implements List<T> {
   ///   noSuchMethod(Invocation invocation) {
   ///     log(invocation);
   ///     super.noSuchMethod(invocation); // Will throw.
   ///   }
   /// }
   /// void main() {
   ///   MockList().add(42);
   /// }
   /// ```
   /// This code has no compile-time warnings or errors even though
   /// the `MockList` class has no concrete implementation of
   /// any of the `List` interface methods.
   /// Calls to `List` methods are forwarded to `noSuchMethod`,
   /// so this code will `log` an invocation similar to
   /// `Invocation.method(#add, [42])` and then throw.
   ///
   /// If a value is returned from `noSuchMethod`,
   /// it becomes the result of the original invocation.
   /// If the value is not of a type that can be returned by the original
   /// invocation, a type error occurs at the invocation.
   ///
   /// The default behavior is to throw a [NoSuchMethodError].
   @pragma("vm:entry-point")
   external dynamic noSuchMethod(Invocation invocation);

   /// A representation of the runtime type of the object.
   external Type get runtimeType;

   /// Creates a combined hash code for a number of objects.
   ///
   /// The hash code is computed for all arguments that are actually
   /// supplied, even if they are `null`, by numerically combining the
   /// [Object.hashCode] of each argument.
   ///
   /// Example:
   /// ```dart
   /// class SomeObject {
   ///   final Object a, b, c;
   ///   SomeObject(this.a, this.b, this.c);
   ///   bool operator ==(Object other) =>
   ///       other is SomeObject && a == other.a && b == other.b && c == other.c;
   ///   int get hashCode => Object.hash(a, b, c);
   /// }
   /// ```
   ///
   /// The computed value will be consistent when the function is called
   /// with the same arguments multiple times
   /// during the execution of a single program.
   ///
   /// The hash value generated by this function is *not* guaranteed to be stable
   /// over different runs of the same program,
   /// or between code run in different isolates of the same program.
   /// The exact algorithm used may differ between different platforms,
   /// or between different versions of the platform libraries,
   /// and it may depend on values that change on each program execution.
   ///
   /// The [hashAll] function gives the same result as this function when
   /// called with a collection containing the actual arguments
   /// to this function in the same order.
   @Since("2.14")
   static int hash(Object? object1, Object? object2,
       [Object? object3 = sentinelValue,
       Object? object4 = sentinelValue,
       Object? object5 = sentinelValue,
       Object? object6 = sentinelValue,
       Object? object7 = sentinelValue,
       Object? object8 = sentinelValue,
       Object? object9 = sentinelValue,
       Object? object10 = sentinelValue,
       Object? object11 = sentinelValue,
       Object? object12 = sentinelValue,
       Object? object13 = sentinelValue,
       Object? object14 = sentinelValue,
       Object? object15 = sentinelValue,
       Object? object16 = sentinelValue,
       Object? object17 = sentinelValue,
       Object? object18 = sentinelValue,
       Object? object19 = sentinelValue,
       Object? object20 = sentinelValue]) {
     if (sentinelValue == object3) {
       return SystemHash.hash2(object1.hashCode, object2.hashCode, _hashSeed);
     }
     if (sentinelValue == object4) {
       return SystemHash.hash3(
           object1.hashCode, object2.hashCode, object3.hashCode, _hashSeed);
     }
     if (sentinelValue == object5) {
       return SystemHash.hash4(object1.hashCode, object2.hashCode,
           object3.hashCode, object4.hashCode, _hashSeed);
     }
     if (sentinelValue == object6) {
       return SystemHash.hash5(object1.hashCode, object2.hashCode,
           object3.hashCode, object4.hashCode, object5.hashCode, _hashSeed);
     }
     if (sentinelValue == object7) {
       return SystemHash.hash6(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object8) {
       return SystemHash.hash7(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object9) {
       return SystemHash.hash8(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object10) {
       return SystemHash.hash9(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           object9.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object11) {
       return SystemHash.hash10(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           object9.hashCode,
           object10.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object12) {
       return SystemHash.hash11(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           object9.hashCode,
           object10.hashCode,
           object11.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object13) {
       return SystemHash.hash12(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           object9.hashCode,
           object10.hashCode,
           object11.hashCode,
           object12.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object14) {
       return SystemHash.hash13(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           object9.hashCode,
           object10.hashCode,
           object11.hashCode,
           object12.hashCode,
           object13.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object15) {
       return SystemHash.hash14(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           object9.hashCode,
           object10.hashCode,
           object11.hashCode,
           object12.hashCode,
           object13.hashCode,
           object14.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object16) {
       return SystemHash.hash15(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           object9.hashCode,
           object10.hashCode,
           object11.hashCode,
           object12.hashCode,
           object13.hashCode,
           object14.hashCode,
           object15.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object17) {
       return SystemHash.hash16(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           object9.hashCode,
           object10.hashCode,
           object11.hashCode,
           object12.hashCode,
           object13.hashCode,
           object14.hashCode,
           object15.hashCode,
           object16.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object18) {
       return SystemHash.hash17(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           object9.hashCode,
           object10.hashCode,
           object11.hashCode,
           object12.hashCode,
           object13.hashCode,
           object14.hashCode,
           object15.hashCode,
           object16.hashCode,
           object17.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object19) {
       return SystemHash.hash18(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           object9.hashCode,
           object10.hashCode,
           object11.hashCode,
           object12.hashCode,
           object13.hashCode,
           object14.hashCode,
           object15.hashCode,
           object16.hashCode,
           object17.hashCode,
           object18.hashCode,
           _hashSeed);
     }
     if (sentinelValue == object20) {
       return SystemHash.hash19(
           object1.hashCode,
           object2.hashCode,
           object3.hashCode,
           object4.hashCode,
           object5.hashCode,
           object6.hashCode,
           object7.hashCode,
           object8.hashCode,
           object9.hashCode,
           object10.hashCode,
           object11.hashCode,
           object12.hashCode,
           object13.hashCode,
           object14.hashCode,
           object15.hashCode,
           object16.hashCode,
           object17.hashCode,
           object18.hashCode,
           object19.hashCode,
           _hashSeed);
     }
     return SystemHash.hash20(
         object1.hashCode,
         object2.hashCode,
         object3.hashCode,
         object4.hashCode,
         object5.hashCode,
         object6.hashCode,
         object7.hashCode,
         object8.hashCode,
         object9.hashCode,
         object10.hashCode,
         object11.hashCode,
         object12.hashCode,
         object13.hashCode,
         object14.hashCode,
         object15.hashCode,
         object16.hashCode,
         object17.hashCode,
         object18.hashCode,
         object19.hashCode,
         object20.hashCode,
         _hashSeed);
   }

   /// Creates a combined hash code for a sequence of objects.
   ///
   /// The hash code is computed for elements in [objects],
   /// even if they are `null`,
   /// by numerically combining the [Object.hashCode] of each element
   /// in iteration order.
   ///
   /// The result of `hashAll([o])` is not `o.hashCode`.
   ///
   /// Example:
   /// ```dart
   /// class SomeObject {
   ///   final List<String> path;
   ///   SomeObject(this.path);
   ///   bool operator ==(Object other) {
   ///     if (other is SomeObject) {
   ///       if (path.length != other.path.length) return false;
   ///       for (int i = 0; i < path.length; i++) {
   ///         if (path[i] != other.path[i]) return false;
   ///       }
   ///       return true;
   ///     }
   ///     return false;
   ///   }
   ///
   ///   int get hashCode => Object.hashAll(path);
   /// }
   /// ```
   ///
   /// The computed value will be consistent when the function is called
   /// again with objects that have the same hash codes in the same order
   /// during an execution of a single program.
   ///
   /// The hash value generated by this function is *not* guaranteed to be stable
   /// over different runs of the same program,
   /// or between code run in different isolates of the same program.
   /// The exact algorithm used may differ between different platforms,
   /// or between different versions of the platform libraries,
   /// and it may depend on values that change on each program execution.
   @Since("2.14")
   static int hashAll(Iterable<Object?> objects) {
     int hash = _hashSeed;
     for (var object in objects) {
       hash = SystemHash.combine(hash, object.hashCode);
     }
     return SystemHash.finish(hash);
   }

   /// Creates a combined hash code for a collection of objects.
   ///
   /// The hash code is computed for elements in [objects],
   /// even if they are `null`,
   /// by numerically combining the [Object.hashCode] of each element
   /// in an order independent way.
   ///
   /// The result of `unorderedHashAll({o})` is not `o.hashCode`.
   ///
   /// Example:
   /// ```dart
   /// bool setEquals<T>(Set<T> set1, Set<T> set2) {
   ///   var hashCode1 = Object.unorderedHashAll(set1);
   ///   var hashCode2 = Object.unorderedHashAll(set2);
   ///   if (hashCode1 != hashCode2) return false;
   ///   // Compare elements ...
   /// }
   /// ```
   ///
   /// The computed value will be consistent when the function is called
   /// again with objects that have the same hash codes
   /// during an execution of a single program,
   /// even if the objects are not necessarily in the same order,
   ///
   /// The hash value generated by this function is *not* guaranteed to be stable
   /// over different runs of the same program.
   /// The exact algorithm used may differ between different platforms,
   /// or between different versions of the platform libraries,
   /// and it may depend on values that change per program run
   @Since("2.14")
   static int hashAllUnordered(Iterable<Object?> objects) {
     int sum = 0;
     int count = 0;
     const int mask = 0x3FFFFFFF;
     for (var object in objects) {
       int objectHash = SystemHash.smear(object.hashCode);
       sum = (sum + objectHash) & mask;
       count += 1;
     }
     return SystemHash.hash2(sum, count);
   }
 }

 // A per-isolate seed for hash code computations.
 final int _hashSeed = identityHashCode(Object);
	// Copyright (c) 2012, 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.

	part of dart.core;

	/// The base class for all Dart objects except `null`.
	///
	/// Because `Object` is a root of the non-nullable Dart class hierarchy,
	/// every other non-`Null` Dart class is a subclass of `Object`.
	///
	/// When you define a class, you should consider overriding [toString]
	/// to return a string describing an instance of that class.
	/// You might also need to define [hashCode] and [operator ==], as described in the
	/// [Implementing map keys](https://dart.dev/guides/libraries/library-tour#implementing-map-keys)
	/// section of the [library tour](https://dart.dev/guides/libraries/library-tour).
	@pragma("vm:entry-point")
	class Object {
	/// Creates a new [Object] instance.
	///
	/// [Object] instances have no meaningful state, and are only useful
	/// through their identity. An [Object] instance is equal to itself
	/// only.
	@pragma("vm:recognized", "other")
	const Object();

	/// The equality operator.
	///
	/// The default behavior for all [Object]s is to return true if and
	/// only if this object and [other] are the same object.
	///
	/// Override this method to specify a different equality relation on
	/// a class. The overriding method must still be an equivalence relation.
	/// That is, it must be:
	///
	/// * Total: It must return a boolean for all arguments. It should never throw.
	///
	/// * Reflexive: For all objects `o`, `o == o` must be true.
	///
	/// * Symmetric: For all objects `o1` and `o2`, `o1 == o2` and `o2 == o1` must
	/// either both be true, or both be false.
	///
	/// * Transitive: For all objects `o1`, `o2`, and `o3`, if `o1 == o2` and
	/// `o2 == o3` are true, then `o1 == o3` must be true.
	///
	/// The method should also be consistent over time,
	/// so whether two objects are equal should only change
	/// if at least one of the objects was modified.
	///
	/// If a subclass overrides the equality operator, it should override
	/// the [hashCode] method as well to maintain consistency.
	external bool operator ==(Object other);

	/// The hash code for this object.
	///
	/// A hash code is a single integer which represents the state of the object
	/// that affects [operator ==] comparisons.
	///
	/// All objects have hash codes.
	/// The default hash code implemented by [Object]
	/// represents only the identity of the object,
	/// the same way as the default [operator ==] implementation only considers objects
	/// equal if they are identical (see [identityHashCode]).
	///
	/// If [operator ==] is overridden to use the object state instead,
	/// the hash code must also be changed to represent that state,
	/// otherwise the object cannot be used in hash based data structures
	/// like the default [Set] and [Map] implementations.
	///
	/// Hash codes must be the same for objects that are equal to each other
	/// according to [operator ==].
	/// The hash code of an object should only change if the object changes
	/// in a way that affects equality.
	/// There are no further requirements for the hash codes.
	/// They need not be consistent between executions of the same program
	/// and there are no distribution guarantees.
	///
	/// Objects that are not equal are allowed to have the same hash code.
	/// It is even technically allowed that all instances have the same hash code,
	/// but if clashes happen too often,
	/// it may reduce the efficiency of hash-based data structures
	/// like [HashSet] or [HashMap].
	///
	/// If a subclass overrides [hashCode], it should override the
	/// [operator ==] operator as well to maintain consistency.
	external int get hashCode;

	/// A string representation of this object.
	///
	/// Some classes have a default textual representation,
	/// often paired with a static `parse` function (like [int.parse]).
	/// These classes will provide the textual representation as
	/// their string representation.
	///
	/// Other classes have no meaningful textual representation
	/// that a program will care about.
	/// Such classes will typically override `toString` to provide
	/// useful information when inspecting the object,
	/// mainly for debugging or logging.
	external String toString();

	/// Invoked when a non-existent method or property is accessed.
	///
	/// A dynamic member invocation can attempt to call a member which
	/// doesn't exist on the receiving object. Example:
	/// ```dart
	/// dynamic object = 1;
	/// object.add(42); // Statically allowed, run-time error
	/// ```
	/// This invalid code will invoke the `noSuchMethod` method
	/// of the integer `1` with an [Invocation] representing the
	/// `.add(42)` call and arguments (which then throws).
	///
	/// Classes can override [noSuchMethod] to provide custom behavior
	/// for such invalid dynamic invocations.
	///
	/// A class with a non-default [noSuchMethod] invocation can also
	/// omit implementations for members of its interface.
	/// Example:
	/// ```dart
	/// class MockList<T> implements List<T> {
	/// noSuchMethod(Invocation invocation) {
	/// log(invocation);
	/// super.noSuchMethod(invocation); // Will throw.
	/// }
	/// }
	/// void main() {
	/// MockList().add(42);
	/// }
	/// ```
	/// This code has no compile-time warnings or errors even though
	/// the `MockList` class has no concrete implementation of
	/// any of the `List` interface methods.
	/// Calls to `List` methods are forwarded to `noSuchMethod`,
	/// so this code will `log` an invocation similar to
	/// `Invocation.method(#add, [42])` and then throw.
	///
	/// If a value is returned from `noSuchMethod`,
	/// it becomes the result of the original invocation.
	/// If the value is not of a type that can be returned by the original
	/// invocation, a type error occurs at the invocation.
	///
	/// The default behavior is to throw a [NoSuchMethodError].
	@pragma("vm:entry-point")
	external dynamic noSuchMethod(Invocation invocation);

	/// A representation of the runtime type of the object.
	external Type get runtimeType;

	/// Creates a combined hash code for a number of objects.
	///
	/// The hash code is computed for all arguments that are actually
	/// supplied, even if they are `null`, by numerically combining the
	/// [Object.hashCode] of each argument.
	///
	/// Example:
	/// ```dart
	/// class SomeObject {
	/// final Object a, b, c;
	/// SomeObject(this.a, this.b, this.c);
	/// bool operator ==(Object other) =>
	/// other is SomeObject && a == other.a && b == other.b && c == other.c;
	/// int get hashCode => Object.hash(a, b, c);
	/// }
	/// ```
	///
	/// The computed value will be consistent when the function is called
	/// with the same arguments multiple times
	/// during the execution of a single program.
	///
	/// The hash value generated by this function is not guaranteed to be stable
	/// over different runs of the same program,
	/// or between code run in different isolates of the same program.
	/// The exact algorithm used may differ between different platforms,
	/// or between different versions of the platform libraries,
	/// and it may depend on values that change on each program execution.
	///
	/// The [hashAll] function gives the same result as this function when
	/// called with a collection containing the actual arguments
	/// to this function in the same order.
	@Since("2.14")
	static int hash(Object? object1, Object? object2,
	[Object? object3 = sentinelValue,
	Object? object4 = sentinelValue,
	Object? object5 = sentinelValue,
	Object? object6 = sentinelValue,
	Object? object7 = sentinelValue,
	Object? object8 = sentinelValue,
	Object? object9 = sentinelValue,
	Object? object10 = sentinelValue,
	Object? object11 = sentinelValue,
	Object? object12 = sentinelValue,
	Object? object13 = sentinelValue,
	Object? object14 = sentinelValue,
	Object? object15 = sentinelValue,
	Object? object16 = sentinelValue,
	Object? object17 = sentinelValue,
	Object? object18 = sentinelValue,
	Object? object19 = sentinelValue,
	Object? object20 = sentinelValue]) {
	if (sentinelValue == object3) {
	return SystemHash.hash2(object1.hashCode, object2.hashCode, _hashSeed);
	}
	if (sentinelValue == object4) {
	return SystemHash.hash3(
	object1.hashCode, object2.hashCode, object3.hashCode, _hashSeed);
	}
	if (sentinelValue == object5) {
	return SystemHash.hash4(object1.hashCode, object2.hashCode,
	object3.hashCode, object4.hashCode, _hashSeed);
	}
	if (sentinelValue == object6) {
	return SystemHash.hash5(object1.hashCode, object2.hashCode,
	object3.hashCode, object4.hashCode, object5.hashCode, _hashSeed);
	}
	if (sentinelValue == object7) {
	return SystemHash.hash6(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object8) {
	return SystemHash.hash7(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object9) {
	return SystemHash.hash8(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object10) {
	return SystemHash.hash9(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object11) {
	return SystemHash.hash10(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	object10.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object12) {
	return SystemHash.hash11(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	object10.hashCode,
	object11.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object13) {
	return SystemHash.hash12(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	object10.hashCode,
	object11.hashCode,
	object12.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object14) {
	return SystemHash.hash13(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	object10.hashCode,
	object11.hashCode,
	object12.hashCode,
	object13.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object15) {
	return SystemHash.hash14(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	object10.hashCode,
	object11.hashCode,
	object12.hashCode,
	object13.hashCode,
	object14.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object16) {
	return SystemHash.hash15(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	object10.hashCode,
	object11.hashCode,
	object12.hashCode,
	object13.hashCode,
	object14.hashCode,
	object15.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object17) {
	return SystemHash.hash16(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	object10.hashCode,
	object11.hashCode,
	object12.hashCode,
	object13.hashCode,
	object14.hashCode,
	object15.hashCode,
	object16.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object18) {
	return SystemHash.hash17(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	object10.hashCode,
	object11.hashCode,
	object12.hashCode,
	object13.hashCode,
	object14.hashCode,
	object15.hashCode,
	object16.hashCode,
	object17.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object19) {
	return SystemHash.hash18(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	object10.hashCode,
	object11.hashCode,
	object12.hashCode,
	object13.hashCode,
	object14.hashCode,
	object15.hashCode,
	object16.hashCode,
	object17.hashCode,
	object18.hashCode,
	_hashSeed);
	}
	if (sentinelValue == object20) {
	return SystemHash.hash19(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	object10.hashCode,
	object11.hashCode,
	object12.hashCode,
	object13.hashCode,
	object14.hashCode,
	object15.hashCode,
	object16.hashCode,
	object17.hashCode,
	object18.hashCode,
	object19.hashCode,
	_hashSeed);
	}
	return SystemHash.hash20(
	object1.hashCode,
	object2.hashCode,
	object3.hashCode,
	object4.hashCode,
	object5.hashCode,
	object6.hashCode,
	object7.hashCode,
	object8.hashCode,
	object9.hashCode,
	object10.hashCode,
	object11.hashCode,
	object12.hashCode,
	object13.hashCode,
	object14.hashCode,
	object15.hashCode,
	object16.hashCode,
	object17.hashCode,
	object18.hashCode,
	object19.hashCode,
	object20.hashCode,
	_hashSeed);
	}

	/// Creates a combined hash code for a sequence of objects.
	///
	/// The hash code is computed for elements in [objects],
	/// even if they are `null`,
	/// by numerically combining the [Object.hashCode] of each element
	/// in iteration order.
	///
	/// The result of `hashAll([o])` is not `o.hashCode`.
	///
	/// Example:
	/// ```dart
	/// class SomeObject {
	/// final List<String> path;
	/// SomeObject(this.path);
	/// bool operator ==(Object other) {
	/// if (other is SomeObject) {
	/// if (path.length != other.path.length) return false;
	/// for (int i = 0; i < path.length; i++) {
	/// if (path[i] != other.path[i]) return false;
	/// }
	/// return true;
	/// }
	/// return false;
	/// }
	///
	/// int get hashCode => Object.hashAll(path);
	/// }
	/// ```
	///
	/// The computed value will be consistent when the function is called
	/// again with objects that have the same hash codes in the same order
	/// during an execution of a single program.
	///
	/// The hash value generated by this function is not guaranteed to be stable
	/// over different runs of the same program,
	/// or between code run in different isolates of the same program.
	/// The exact algorithm used may differ between different platforms,
	/// or between different versions of the platform libraries,
	/// and it may depend on values that change on each program execution.
	@Since("2.14")
	static int hashAll(Iterable<Object?> objects) {
	int hash = _hashSeed;
	for (var object in objects) {
	hash = SystemHash.combine(hash, object.hashCode);
	}
	return SystemHash.finish(hash);
	}

	/// Creates a combined hash code for a collection of objects.
	///
	/// The hash code is computed for elements in [objects],
	/// even if they are `null`,
	/// by numerically combining the [Object.hashCode] of each element
	/// in an order independent way.
	///
	/// The result of `unorderedHashAll({o})` is not `o.hashCode`.
	///
	/// Example:
	/// ```dart
	/// bool setEquals<T>(Set<T> set1, Set<T> set2) {
	/// var hashCode1 = Object.unorderedHashAll(set1);
	/// var hashCode2 = Object.unorderedHashAll(set2);
	/// if (hashCode1 != hashCode2) return false;
	/// // Compare elements ...
	/// }
	/// ```
	///
	/// The computed value will be consistent when the function is called
	/// again with objects that have the same hash codes
	/// during an execution of a single program,
	/// even if the objects are not necessarily in the same order,
	///
	/// The hash value generated by this function is not guaranteed to be stable
	/// over different runs of the same program.
	/// The exact algorithm used may differ between different platforms,
	/// or between different versions of the platform libraries,
	/// and it may depend on values that change per program run
	@Since("2.14")
	static int hashAllUnordered(Iterable<Object?> objects) {
	int sum = 0;
	int count = 0;
	const int mask = 0x3FFFFFFF;
	for (var object in objects) {
	int objectHash = SystemHash.smear(object.hashCode);
	sum = (sum + objectHash) & mask;
	count += 1;
	}
	return SystemHash.hash2(sum, count);
	}
	}

	// A per-isolate seed for hash code computations.
	final int _hashSeed = identityHashCode(Object);