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// Copyright (c) 2014, 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.
/**
* Defines the type model. The type model is part of the
* [element model](../dart_element_element/dart_element_element-library.html)
* in that most types are defined by Dart code (the types `dynamic` and `void`
* being the notable exceptions). All types are represented by an instance of a
* subclass of [DartType].
*
* Other than `dynamic` and `void`, all of the types define either the interface
* defined by a class (an instance of [InterfaceType]) or the type of a function
* (an instance of [FunctionType]).
*
* We make a distinction between the declaration of a class (a [ClassElement])
* and the type defined by that class (an [InterfaceType]). The biggest reason
* for the distinction is to allow us to more cleanly represent the distinction
* between type parameters and type arguments. For example, if we define a class
* as `class Pair<K, V> {}`, the declarations of `K` and `V` represent type
* parameters. But if we declare a variable as `Pair<String, int> pair;` the
* references to `String` and `int` are type arguments.
*/
import 'package:analyzer/dart/element/element.dart';
import 'package:analyzer/src/dart/element/type.dart' show InterfaceTypeImpl;
import 'package:analyzer/src/generated/type_system.dart' show TypeSystem;
/**
* The type associated with elements in the element model.
*
* Clients may not extend, implement or mix-in this class.
*/
abstract class DartType {
/**
* An empty list of types.
*/
static const List<DartType> EMPTY_LIST = const <DartType>[];
/**
* Return the name of this type as it should appear when presented to users in
* contexts such as error messages.
*/
String get displayName;
/**
* Return the element representing the declaration of this type, or `null` if
* the type has not, or cannot, be associated with an element. The former case
* will occur if the element model is not yet complete; the latter case will
* occur if this object represents an undefined type.
*/
Element get element;
/**
* Return `true` if this type represents the bottom type.
*/
bool get isBottom;
/**
* Return `true` if this type represents the type 'Future' defined in the
* dart:async library.
*/
bool get isDartAsyncFuture;
/**
* Return `true` if this type represents the type 'FutureOr<T>' defined in the
* dart:async library.
*/
bool get isDartAsyncFutureOr;
/**
* Return `true` if this type represents the type 'Function' defined in the
* dart:core library.
*/
bool get isDartCoreFunction;
/**
* Return `true` if this type represents the type 'Null' defined in the
* dart:core library.
*/
bool get isDartCoreNull;
/**
* Return `true` if this type represents the type 'dynamic'.
*/
bool get isDynamic;
/**
* Return `true` if this type represents the type 'Object'.
*/
bool get isObject;
/**
* Return `true` if this type represents a typename that couldn't be resolved.
*/
bool get isUndefined;
/**
* Return `true` if this type represents the type 'void'.
*/
bool get isVoid;
/**
* Return the name of this type, or `null` if the type does not have a name,
* such as when the type represents the type of an unnamed function.
*/
String get name;
/**
* Implements the function "flatten" defined in the spec, where T is this
* type:
*
* If T = Future<S> then flatten(T) = flatten(S).
*
* Otherwise if T <: Future then let S be a type such that T << Future<S>
* and for all R, if T << Future<R> then S << R. Then flatten(T) = S.
*
* In any other circumstance, flatten(T) = T.
*/
DartType flattenFutures(TypeSystem typeSystem);
/**
* Return `true` if this type is assignable to the given [type]. A type
* <i>T</i> may be assigned to a type <i>S</i>, written <i>T</i> &hArr;
* <i>S</i>, iff either <i>T</i> <: <i>S</i> or <i>S</i> <: <i>T</i>.
*/
bool isAssignableTo(DartType type);
/// Indicates whether `this` represents a type that is equivalent to `dest`.
///
/// This is different from `operator==`. Consider for example:
///
/// typedef void F<T>(); // T not used!
///
/// `operator==` would consider F<int> and F<bool> to be different types;
/// `isEquivalentTo` considers them to be equivalent.
bool isEquivalentTo(DartType dest);
/**
* Return `true` if this type is more specific than the given [type].
*/
bool isMoreSpecificThan(DartType type);
/**
* Return `true` if this type is a subtype of the given [type].
*/
bool isSubtypeOf(DartType type);
/**
* Return `true` if this type is a supertype of the given [type]. A type
* <i>S</i> is a supertype of <i>T</i>, written <i>S</i> :> <i>T</i>, iff
* <i>T</i> is a subtype of <i>S</i>.
*/
bool isSupertypeOf(DartType type);
/**
* If this type is a [TypeParameterType], returns its bound if it has one, or
* [objectType] otherwise.
*
* For any other type, returns `this`. Applies recursively -- if the bound is
* itself a type parameter, that is resolved too.
*/
DartType resolveToBound(DartType objectType);
/**
* Return the type resulting from substituting the given [argumentTypes] for
* the given [parameterTypes] in this type. The specification defines this
* operation in section 2:
* <blockquote>
* The notation <i>[x<sub>1</sub>, ..., x<sub>n</sub>/y<sub>1</sub>, ...,
* y<sub>n</sub>]E</i> denotes a copy of <i>E</i> in which all occurrences of
* <i>y<sub>i</sub>, 1 <= i <= n</i> have been replaced with
* <i>x<sub>i</sub></i>.
* </blockquote>
* Note that, contrary to the specification, this method will not create a
* copy of this type if no substitutions were required, but will return this
* type directly.
*
* Note too that the current implementation of this method is only guaranteed
* to work when the parameter types are type variables.
*/
DartType substitute2(
List<DartType> argumentTypes, List<DartType> parameterTypes);
}
/**
* The type of a function, method, constructor, getter, or setter. Function
* types come in three variations:
*
* * The types of functions that only have required parameters. These have the
* general form <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>) &rarr; T</i>.
* * The types of functions with optional positional parameters. These have the
* general form <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>, [T<sub>n+1</sub>
* &hellip;, T<sub>n+k</sub>]) &rarr; T</i>.
* * The types of functions with named parameters. These have the general form
* <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>, {T<sub>x1</sub> x1, &hellip;,
* T<sub>xk</sub> xk}) &rarr; T</i>.
*
* Clients may not extend, implement or mix-in this class.
*/
abstract class FunctionType implements ParameterizedType {
/**
* Deprecated: use [typeFormals].
*/
@deprecated
List<TypeParameterElement> get boundTypeParameters;
/**
* Return a map from the names of named parameters to the types of the named
* parameters of this type of function. The entries in the map will be
* iterated in the same order as the order in which the named parameters were
* defined. If there were no named parameters declared then the map will be
* empty.
*/
Map<String, DartType> get namedParameterTypes;
/**
* The names of the required positional parameters of this type of function,
* in the order that the parameters appear.
*/
List<String> get normalParameterNames;
/**
* Return a list containing the types of the normal parameters of this type of
* function. The parameter types are in the same order as they appear in the
* declaration of the function.
*/
List<DartType> get normalParameterTypes;
/**
* The names of the optional positional parameters of this type of function,
* in the order that the parameters appear.
*/
List<String> get optionalParameterNames;
/**
* Return a map from the names of optional (positional) parameters to the
* types of the optional parameters of this type of function. The entries in
* the map will be iterated in the same order as the order in which the
* optional parameters were defined. If there were no optional parameters
* declared then the map will be empty.
*/
List<DartType> get optionalParameterTypes;
/**
* Return a list containing the parameters elements of this type of function.
* The parameter types are in the same order as they appear in the declaration
* of the function.
*/
List<ParameterElement> get parameters;
/**
* Return the type of object returned by this type of function.
*/
DartType get returnType;
/**
* The formal type parameters of this generic function.
* For example `<T> T -> T`.
*
* These are distinct from the [typeParameters] list, which contains type
* parameters from surrounding contexts, and thus are free type variables from
* the perspective of this function type.
*/
List<TypeParameterElement> get typeFormals;
@override
FunctionType instantiate(List<DartType> argumentTypes);
/**
* Return `true` if this type is a subtype of the given [type].
*
* A function type <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>) &rarr; T</i> is
* a subtype of the function type <i>(S<sub>1</sub>, &hellip;, S<sub>n</sub>)
* &rarr; S</i>, if all of the following conditions are met:
*
* * Either
* * <i>S</i> is void, or
* * <i>T &hArr; S</i>.
*
* * For all <i>i</i>, 1 <= <i>i</i> <= <i>n</i>, <i>T<sub>i</sub> &hArr;
* S<sub>i</sub></i>.
*
* A function type <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>,
* [T<sub>n+1</sub>, &hellip;, T<sub>n+k</sub>]) &rarr; T</i> is a subtype of
* the function type <i>(S<sub>1</sub>, &hellip;, S<sub>n</sub>,
* [S<sub>n+1</sub>, &hellip;, S<sub>n+m</sub>]) &rarr; S</i>, if all of the
* following conditions are met:
*
* * Either
* * <i>S</i> is void, or
* * <i>T &hArr; S</i>.
*
* * <i>k</i> >= <i>m</i> and for all <i>i</i>, 1 <= <i>i</i> <= <i>n+m</i>,
* <i>T<sub>i</sub> &hArr; S<sub>i</sub></i>.
*
* A function type <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>,
* {T<sub>x1</sub> x1, &hellip;, T<sub>xk</sub> xk}) &rarr; T</i> is a subtype
* of the function type <i>(S<sub>1</sub>, &hellip;, S<sub>n</sub>,
* {S<sub>y1</sub> y1, &hellip;, S<sub>ym</sub> ym}) &rarr; S</i>, if all of
* the following conditions are met:
* * Either
* * <i>S</i> is void,
* * or <i>T &hArr; S</i>.
*
* * For all <i>i</i>, 1 <= <i>i</i> <= <i>n</i>, <i>T<sub>i</sub> &hArr;
* S<sub>i</sub></i>.
* * <i>k</i> >= <i>m</i> and <i>y<sub>i</sub></i> in <i>{x<sub>1</sub>,
* &hellip;, x<sub>k</sub>}</i>, 1 <= <i>i</i> <= <i>m</i>.
* * For all <i>y<sub>i</sub></i> in <i>{y<sub>1</sub>, &hellip;,
* y<sub>m</sub>}</i>, <i>y<sub>i</sub> = x<sub>j</sub> => Tj &hArr; Si</i>.
*
* In addition, the following subtype rules apply:
*
* <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>, []) &rarr; T <: (T<sub>1</sub>,
* &hellip;, T<sub>n</sub>) &rarr; T.</i><br>
* <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>) &rarr; T <: (T<sub>1</sub>,
* &hellip;, T<sub>n</sub>, {}) &rarr; T.</i><br>
* <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>, {}) &rarr; T <: (T<sub>1</sub>,
* &hellip;, T<sub>n</sub>) &rarr; T.</i><br>
* <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>) &rarr; T <: (T<sub>1</sub>,
* &hellip;, T<sub>n</sub>, []) &rarr; T.</i>
*
* All functions implement the class `Function`. However not all function
* types are a subtype of `Function`. If an interface type <i>I</i> includes a
* method named `call()`, and the type of `call()` is the function type
* <i>F</i>, then <i>I</i> is considered to be a subtype of <i>F</i>.
*/
@override
bool isSubtypeOf(DartType type);
@override
FunctionType substitute2(
List<DartType> argumentTypes, List<DartType> parameterTypes);
/**
* Return the type resulting from substituting the given [argumentTypes] for
* this type's parameters. This is fully equivalent to
* `substitute(argumentTypes, getTypeArguments())`.
*/
@deprecated // use instantiate
FunctionType substitute3(List<DartType> argumentTypes);
}
/**
* The type introduced by either a class or an interface, or a reference to such
* a type.
*
* Clients may not extend, implement or mix-in this class.
*/
abstract class InterfaceType implements ParameterizedType {
/**
* An empty list of types.
*/
static const List<InterfaceType> EMPTY_LIST = const <InterfaceType>[];
/**
* Return a list containing all of the accessors (getters and setters)
* declared in this type.
*/
List<PropertyAccessorElement> get accessors;
/**
* Return a list containing all of the constructors declared in this type.
*/
List<ConstructorElement> get constructors;
@override
ClassElement get element;
/**
* Return a list containing all of the interfaces that are implemented by this
* interface. Note that this is <b>not</b>, in general, equivalent to getting
* the interfaces from this type's element because the types returned by this
* method will have had their type parameters replaced.
*/
List<InterfaceType> get interfaces;
/**
* Return a list containing all of the methods declared in this type.
*/
List<MethodElement> get methods;
/**
* Return a list containing all of the mixins that are applied to the class
* being extended in order to derive the superclass of this class. Note that
* this is <b>not</b>, in general, equivalent to getting the mixins from this
* type's element because the types returned by this method will have had
* their type parameters replaced.
*/
List<InterfaceType> get mixins;
/**
* Return the type representing the superclass of this type, or null if this
* type represents the class 'Object'. Note that this is <b>not</b>, in
* general, equivalent to getting the superclass from this type's element
* because the type returned by this method will have had it's type parameters
* replaced.
*/
InterfaceType get superclass;
/**
* Return the element representing the getter with the given [name] that is
* declared in this class, or `null` if this class does not declare a getter
* with the given name.
*/
PropertyAccessorElement getGetter(String name);
/**
* Return the element representing the method with the given [name] that is
* declared in this class, or `null` if this class does not declare a method
* with the given name.
*/
MethodElement getMethod(String name);
/**
* Return the element representing the setter with the given [name] that is
* declared in this class, or `null` if this class does not declare a setter
* with the given name.
*/
PropertyAccessorElement getSetter(String name);
@override
InterfaceType instantiate(List<DartType> argumentTypes);
/**
* Return `true` if this type is a direct supertype of the given [type]. The
* implicit interface of class <i>I</i> is a direct supertype of the implicit
* interface of class <i>J</i> iff:
*
* * <i>I</i> is Object, and <i>J</i> has no extends clause.
* * <i>I</i> is listed in the extends clause of <i>J</i>.
* * <i>I</i> is listed in the implements clause of <i>J</i>.
* * <i>I</i> is listed in the with clause of <i>J</i>.
* * <i>J</i> is a mixin application of the mixin of <i>I</i>.
*/
bool isDirectSupertypeOf(InterfaceType type);
/**
* Return `true` if this type is more specific than the given [type]. An
* interface type <i>T</i> is more specific than an interface type <i>S</i>,
* written <i>T &laquo; S</i>, if one of the following conditions is met:
*
* * Reflexivity: <i>T</i> is <i>S</i>.
* * <i>T</i> is bottom.
* * <i>S</i> is dynamic.
* * Direct supertype: <i>S</i> is a direct supertype of <i>T</i>.
* * <i>T</i> is a type parameter and <i>S</i> is the upper bound of <i>T</i>.
* * Covariance: <i>T</i> is of the form <i>I&lt;T<sub>1</sub>, &hellip;,
* T<sub>n</sub>&gt;</i> and S</i> is of the form <i>I&lt;S<sub>1</sub>,
* &hellip;, S<sub>n</sub>&gt;</i> and <i>T<sub>i</sub> &laquo;
* S<sub>i</sub></i>, <i>1 <= i <= n</i>.
* * Transitivity: <i>T &laquo; U</i> and <i>U &laquo; S</i>.
*/
@override
bool isMoreSpecificThan(DartType type);
/**
* Return `true` if this type is a subtype of the given [type]. An interface
* type <i>T</i> is a subtype of an interface type <i>S</i>, written <i>T</i>
* <: <i>S</i>, iff <i>[bottom/dynamic]T</i> &laquo; <i>S</i> (<i>T</i> is
* more specific than <i>S</i>). If an interface type <i>I</i> includes a
* method named <i>call()</i>, and the type of <i>call()</i> is the function
* type <i>F</i>, then <i>I</i> is considered to be a subtype of <i>F</i>.
*/
@override
bool isSubtypeOf(DartType type);
/**
* Return the element representing the constructor that results from looking
* up the constructor with the given [name] in this class with respect to the
* given [library], or `null` if the look up fails. The behavior of this
* method is defined by the Dart Language Specification in section 12.11.1:
* <blockquote>
* If <i>e</i> is of the form <b>new</b> <i>T.id()</i> then let <i>q<i> be the
* constructor <i>T.id</i>, otherwise let <i>q<i> be the constructor <i>T<i>.
* Otherwise, if <i>q</i> is not defined or not accessible, a
* NoSuchMethodException is thrown.
* </blockquote>
*/
ConstructorElement lookUpConstructor(String name, LibraryElement library);
/**
* Return the element representing the getter that results from looking up the
* getter with the given [name] in this class with respect to the given
* [library], or `null` if the look up fails. The behavior of this method is
* defined by the Dart Language Specification in section 12.15.1:
* <blockquote>
* The result of looking up getter (respectively setter) <i>m</i> in class
* <i>C</i> with respect to library <i>L</i> is:
* * If <i>C</i> declares an instance getter (respectively setter) named
* <i>m</i> that is accessible to <i>L</i>, then that getter (respectively
* setter) is the result of the lookup. Otherwise, if <i>C</i> has a
* superclass <i>S</i>, then the result of the lookup is the result of
* looking up getter (respectively setter) <i>m</i> in <i>S</i> with respect
* to <i>L</i>. Otherwise, we say that the lookup has failed.
* </blockquote>
*/
PropertyAccessorElement lookUpGetter(String name, LibraryElement library);
/**
* Return the element representing the getter that results from looking up the
* getter with the given [name] in the superclass of this class with respect
* to the given [library], or `null` if the look up fails. The behavior of
* this method is defined by the Dart Language Specification in section
* 12.15.1:
* <blockquote>
* The result of looking up getter (respectively setter) <i>m</i> in class
* <i>C</i> with respect to library <i>L</i> is:
* * If <i>C</i> declares an instance getter (respectively setter) named
* <i>m</i> that is accessible to <i>L</i>, then that getter (respectively
* setter) is the result of the lookup. Otherwise, if <i>C</i> has a
* superclass <i>S</i>, then the result of the lookup is the result of
* looking up getter (respectively setter) <i>m</i> in <i>S</i> with respect
* to <i>L</i>. Otherwise, we say that the lookup has failed.
* </blockquote>
*/
PropertyAccessorElement lookUpGetterInSuperclass(
String name, LibraryElement library);
/**
* Look up the member with the given [name] in this type and all extended
* and mixed in classes, and by default including [thisType]. If the search
* fails, this will then search interfaces.
*
* Return the element representing the member that was found, or `null` if
* there is no getter with the given name.
*
* The [library] determines if a private member name is visible, and does not
* need to be supplied for public names.
*/
PropertyAccessorElement lookUpInheritedGetter(String name,
{LibraryElement library, bool thisType: true});
/**
* Look up the member with the given [name] in this type and all extended
* and mixed in classes, starting from this type. If the search fails,
* search interfaces.
*
* Return the element representing the member that was found, or `null` if
* there is no getter with the given name.
*
* The [library] determines if a private member name is visible, and does not
* need to be supplied for public names.
*/
ExecutableElement lookUpInheritedGetterOrMethod(String name,
{LibraryElement library});
/**
* Look up the member with the given [name] in this type and all extended
* and mixed in classes, and by default including [thisType]. If the search
* fails, this will then search interfaces.
*
* Return the element representing the member that was found, or `null` if
* there is no getter with the given name.
*
* The [library] determines if a private member name is visible, and does not
* need to be supplied for public names.
*/
MethodElement lookUpInheritedMethod(String name,
{LibraryElement library, bool thisType: true});
/**
* Look up the member with the given [name] in this type and all extended
* and mixed in classes, and by default including [thisType]. If the search
* fails, this will then search interfaces.
*
* Return the element representing the member that was found, or `null` if
* there is no getter with the given name.
*
* The [library] determines if a private member name is visible, and does not
* need to be supplied for public names.
*/
PropertyAccessorElement lookUpInheritedSetter(String name,
{LibraryElement library, bool thisType: true});
/**
* Return the element representing the method that results from looking up the
* method with the given [name] in this class with respect to the given
* [library], or `null` if the look up fails. The behavior of this method is
* defined by the Dart Language Specification in section 12.15.1:
* <blockquote>
* The result of looking up method <i>m</i> in class <i>C</i> with respect to
* library <i>L</i> is:
* * If <i>C</i> declares an instance method named <i>m</i> that is accessible
* to <i>L</i>, then that method is the result of the lookup. Otherwise, if
* <i>C</i> has a superclass <i>S</i>, then the result of the lookup is the
* result of looking up method <i>m</i> in <i>S</i> with respect to <i>L</i>
* Otherwise, we say that the lookup has failed.
* </blockquote>
*/
MethodElement lookUpMethod(String name, LibraryElement library);
/**
* Return the element representing the method that results from looking up the
* method with the given [name] in the superclass of this class with respect
* to the given [library], or `null` if the look up fails. The behavior of
* this method is defined by the Dart Language Specification in section
* 12.15.1:
* <blockquote>
* The result of looking up method <i>m</i> in class <i>C</i> with respect to
* library <i>L</i> is:
* * If <i>C</i> declares an instance method named <i>m</i> that is accessible
* to <i>L</i>, then that method is the result of the lookup. Otherwise, if
* <i>C</i> has a superclass <i>S</i>, then the result of the lookup is the
* result of looking up method <i>m</i> in <i>S</i> with respect to <i>L</i>.
* Otherwise, we say that the lookup has failed.
* </blockquote>
*/
MethodElement lookUpMethodInSuperclass(String name, LibraryElement library);
/**
* Return the element representing the setter that results from looking up the
* setter with the given [name] in this class with respect to the given
* [library], or `null` if the look up fails. The behavior of this method is
* defined by the Dart Language Specification in section 12.16:
* <blockquote>
* The result of looking up getter (respectively setter) <i>m</i> in class
* <i>C</i> with respect to library <i>L</i> is:
* * If <i>C</i> declares an instance getter (respectively setter) named
* <i>m</i> that is accessible to <i>L</i>, then that getter (respectively
* setter) is the result of the lookup. Otherwise, if <i>C</i> has a
* superclass <i>S</i>, then the result of the lookup is the result of
* looking up getter (respectively setter) <i>m</i> in <i>S</i> with respect
* to <i>L</i>. Otherwise, we say that the lookup has failed.
* </blockquote>
*/
PropertyAccessorElement lookUpSetter(String name, LibraryElement library);
/**
* Return the element representing the setter that results from looking up the
* setter with the given [name] in the superclass of this class with respect
* to the given [library], or `null` if the look up fails. The behavior of
* this method is defined by the Dart Language Specification in section 12.16:
* <blockquote>
* The result of looking up getter (respectively setter) <i>m</i> in class
* <i>C</i> with respect to library <i>L</i> is:
* * If <i>C</i> declares an instance getter (respectively setter) named
* <i>m</i> that is accessible to <i>L</i>, then that getter (respectively
* setter) is the result of the lookup. Otherwise, if <i>C</i> has a
* superclass <i>S</i>, then the result of the lookup is the result of
* looking up getter (respectively setter) <i>m</i> in <i>S</i> with respect
* to <i>L</i>. Otherwise, we say that the lookup has failed.
* </blockquote>
*/
PropertyAccessorElement lookUpSetterInSuperclass(
String name, LibraryElement library);
@override
InterfaceType substitute2(
List<DartType> argumentTypes, List<DartType> parameterTypes);
/**
* Return the type resulting from substituting the given arguments for this
* type's parameters. This is fully equivalent to `substitute2(argumentTypes,
* getTypeArguments())`.
*/
@deprecated // use instantiate
InterfaceType substitute4(List<DartType> argumentTypes);
/**
* Returns a "smart" version of the "least upper bound" of the given types.
*
* If these types have the same element and differ only in terms of the type
* arguments, attempts to find a compatible set of type arguments.
*
* Otherwise, returns the same result as [DartType.getLeastUpperBound].
*/
// TODO(brianwilkerson) This needs to be deprecated and moved to TypeSystem.
static InterfaceType getSmartLeastUpperBound(
InterfaceType first, InterfaceType second) =>
InterfaceTypeImpl.getSmartLeastUpperBound(first, second);
}
/**
* A type that can track substituted type parameters, either for itself after
* instantiation, or from a surrounding context.
*
* For example, given a class `Foo<T>`, after instantiation with S for T, it
* will track the substitution `{S/T}`.
*
* This substitution will be propagated to its members. For example, say our
* `Foo<T>` class has a field `T bar;`. When we look up this field, we will get
* back a [FieldElement] that tracks the substituted type as `{S/T}T`, so when
* we ask for the field type we will get `S`.
*
* Clients may not extend, implement or mix-in this class.
*/
abstract class ParameterizedType implements DartType {
/**
* Return a list containing the actual types of the type arguments. If this
* type's element does not have type parameters, then the array should be
* empty (although it is possible for type arguments to be erroneously
* declared). If the element has type parameters and the actual type does not
* explicitly include argument values, then the type "dynamic" will be
* automatically provided.
*/
List<DartType> get typeArguments;
/**
* Return a list containing all of the type parameters declared for this type.
*/
List<TypeParameterElement> get typeParameters;
/**
* Return the type resulting from instantiating (replacing) the given
* [argumentTypes] for this type's bound type parameters.
*/
ParameterizedType instantiate(List<DartType> argumentTypes);
}
/**
* The type introduced by a type parameter.
*
* Clients may not extend, implement or mix-in this class.
*/
abstract class TypeParameterType implements DartType {
/**
* An empty list of type parameter types.
*/
static const List<TypeParameterType> EMPTY_LIST = const <TypeParameterType>[];
/**
* Return the type representing the bound associated with this parameter,
* or `dynamic` if there was no explicit bound.
*/
DartType get bound;
/**
* An object that can be used to identify this type parameter with `==`.
*
* Depending on the use, [bound] may also need to be taken into account.
* A given type parameter, it may have different bounds in different scopes.
* Always consult the bound if that could be relevant.
*/
ElementLocation get definition;
@override
TypeParameterElement get element;
}