JSType (Closure Compiler v20200406 API)

java.lang.Object
- com.google.javascript.rhino.jstype.JSType

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

AllType, BooleanType, NullType, NumberType, ObjectType, StringType, SymbolType, UnionType, VoidType
```
public abstract class JSType
extends java.lang.Object
implements java.io.Serializable
```
Represents JavaScript value types.
Types are split into two separate families: value types and object types.
A special UnknownType exists to represent a wildcard type on which no information can be gathered. In particular, it can assign to everyone, is a subtype of everyone (and everyone is a subtype of it).
If you remove the UnknownType, the set of types in the type system forms a lattice with the isSubtype(com.google.javascript.rhino.jstype.JSType) relation defining the partial order of types. All types are united at the top of the lattice by the AllType and at the bottom by the NoType.

See Also:

Serialized Form

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`JSType.HasPropertyKind` A tristate value returned from canPropertyBeDefined.
`static class`	`JSType.Nullability` Specifies how to express nullability of reference types in annotation strings and error messages.
`static class`	`JSType.SubtypingMode` In files translated from Java, we typecheck null and undefined loosely.
`static class`	`JSType.TypePair` a data structure that represents a pair of types

Field Summary

Fields
Modifier and Type Field and Description

protected TemplateTypeMap templateTypeMap

Fields
Modifier and Type	Field and Description
`protected TemplateTypeMap`	`templateTypeMap`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`static boolean`	`areIdentical(JSType a, JSType b)`
`FunctionType`	`assertFunctionType()` Returns this object cast to FunctionType or throws an exception if it isn't a FunctionType.
`ObjectType`	`assertObjectType()` Returns this object cast to ObjectType or throws an exception if it isn't an ObjectType.
`JSType`	`autobox()` Dereferences a type for property access.
`JSType`	`autoboxesTo()` Turn a scalar type to the corresponding object type.
`boolean`	`canBeCalled()` This predicate is used to test whether a given type can be used as the 'function' in a function call.
`boolean`	`canCastTo(JSType that)` Tests whether values of `this` type can be safely assigned to values of `that` type.
`boolean`	`canTestForEqualityWith(JSType that)` Tests whether `this` and `that` are meaningfully comparable.
`boolean`	`canTestForShallowEqualityWith(JSType that)` Tests whether `this` and `that` are meaningfully comparable using shallow comparison.
`JSType`	`collapseUnion()` Gets the least supertype of this that's not a union.
`boolean`	`containsReferenceAncestor(JSType target)` This function searchers for a type `target` in the reference chain of ProxyObjectTypes
`ObjectType`	`dereference()` Dereferences a type for property access.
`boolean`	`differsFrom(JSType that)` Whether this type is meaningfully different from `that` type for the purposes of data flow analysis.
`boolean`	`equals(java.lang.Object other)`
`JSType`	`findPropertyType(java.lang.String propertyName)` Coerces this type to an Object type, then gets the type of the property whose name is given.
`protected JSType`	`findPropertyTypeWithoutConsideringTemplateTypes(java.lang.String propertyName)` Looks up a property on this type, but without properly replacing any templates in the result.
`java.lang.String`	`getDisplayName()` Returns a user meaningful label for the JSType instance.
`JSType`	`getEnumeratedTypeOfEnumElement()`
`JSType`	`getGreatestSubtype(JSType that)` Gets the greatest subtype of `this` and `that`.
`JSType`	`getGreatestSubtypeWithProperty(java.lang.String propName)`
`JSDocInfo`	`getJSDocInfo()` Gets the docInfo for this type.
`JSType`	`getLeastSupertype(JSType that)` Gets the least supertype of `this` and `that`.
`abstract BooleanLiteralSet`	`getPossibleToBooleanOutcomes()` Computes the set of possible outcomes of the `ToBoolean` predicate for this type.
`JSType.HasPropertyKind`	`getPropertyKind(java.lang.String pname)` Checks whether the property is present on the object.
`JSType.HasPropertyKind`	`getPropertyKind(java.lang.String pname, boolean autobox)` Checks whether the property is present on the object.
`JSType`	`getRestrictedTypeGivenOutcome(Outcome outcome)` Computes the restricted type of this type knowing that the `ToBoolean` predicate has a specific value.
`int`	`getTemplateParamCount()` Return the number of template parameters declared for this type.
`TemplateTypeMap`	`getTemplateTypeMap()` Returns the template type map associated with this type.
`com.google.common.collect.ImmutableList<TemplateType>`	`getTypeParameters()` Return, in order, the sequence of type parameters declared for this type.
`JSType.TypePair`	`getTypesUnderEquality(JSType that)` Computes the subset of `this` and `that` types if equality is observed.
`JSType.TypePair`	`getTypesUnderInequality(JSType that)` Computes the subset of `this` and `that` types if inequality is observed.
`JSType.TypePair`	`getTypesUnderShallowEquality(JSType that)` Computes the subset of `this` and `that` types under shallow equality.
`JSType.TypePair`	`getTypesUnderShallowInequality(JSType that)` Computes the subset of `this` and `that` types under shallow inequality.
`java.lang.Iterable<JSType>`	`getUnionMembers()`
`boolean`	`hasAnyTemplateTypes()`
`boolean`	`hasDisplayName()`
`int`	`hashCode()` Calculates a hash of the object as per `Object.hashCode()`.
`boolean`	`hasProperty(java.lang.String pname)` Checks whether the property is present on the object.
`boolean`	`isAllType()`
`boolean`	`isArrayType()`
`boolean`	`isBooleanObjectType()`
`boolean`	`isBooleanValueType()`
`boolean`	`isBoxableScalar()`
`boolean`	`isCheckedUnknownType()`
`boolean`	`isConstructor()` Whether this type is a `FunctionType` that is a constructor or a named type that points to such a type.
`boolean`	`isDateType()`
`boolean`	`isDict()` Returns true iff `this` can be a `dict`.
`boolean`	`isEmptyType()`
`boolean`	`isEnumElementType()`
`boolean`	`isEnumType()`
`boolean`	`isExplicitlyVoidable()` Tests whether this type explicitly allows undefined, as opposed to ? or *.
`boolean`	`isFunctionPrototypeType()` Whether this is the prototype of a function.
`boolean`	`isFunctionType()` Returns true if toMaybeFunctionType returns a non-null FunctionType.
`boolean`	`isGlobalThisType()` Returns true if this is a global this type.
`boolean`	`isInstanceType()` Whether this type is an Instance object of some constructor.
`boolean`	`isInterface()` Whether this type is a `FunctionType` that is an interface or a named type that points to such a type.
`boolean`	`isLiteralObject()`
`boolean`	`isNamedType()`
`boolean`	`isNativeObjectType()`
`boolean`	`isNominalConstructor()` Whether this type is the original constructor of a nominal type.
`boolean`	`isNominalType()` Whether this type is a nominal type (a named instance object or a named enum).
`boolean`	`isNoObjectType()`
`boolean`	`isNoResolvedType()`
`boolean`	`isNoType()`
`boolean`	`isNullable()` Tests whether this type is nullable.
`boolean`	`isNullType()`
`boolean`	`isNumber()` Tests whether the type is a number (value or Object).
`boolean`	`isNumberObjectType()`
`boolean`	`isNumberValueType()`
`boolean`	`isObject()` Tests whether this type is an `Object`, or any subtype thereof.
`boolean`	`isObjectType()` Tests whether this type is an `Object`, or any subtype thereof.
`boolean`	`isOrdinaryFunction()` Whether this type is a `FunctionType` that is an ordinary function (i.e.
`boolean`	`isRawTypeOfTemplatizedType()`
`boolean`	`isRecordType()`
`boolean`	`isRegexpType()`
`boolean`	`isResolved()` Returns whether the type has undergone resolution.
`boolean`	`isSomeUnknownType()`
`boolean`	`isString()` Tests whether the type is a string (value or Object).
`boolean`	`isStringObjectType()`
`boolean`	`isStringValueType()`
`boolean`	`isStruct()` Returns true iff `this` can be a `struct`.
`boolean`	`isStructuralInterface()`
`boolean`	`isStructuralType()`
`boolean`	`isSubtype(JSType supertype)` Checks whether `this` is a subtype of `that`.
`boolean`	`isSubtype(JSType supertype, JSType.SubtypingMode mode)` Deprecated. Prefer `isSubtype(JSType)` instead.
`boolean`	`isSubtypeOf(JSType supertype)`
`boolean`	`isSubtypeOf(JSType supertype, JSType.SubtypingMode mode)`
`boolean`	`isSubtypeWithoutStructuralTyping(JSType supertype)` the logic of this method is similar to isSubtype, except that it does not perform structural interface matching
`boolean`	`isSuccessfullyResolved()` Returns whether the type has undergone resolution and resolved to a "useful" type.
`boolean`	`isSymbol()`
`boolean`	`isSymbolObjectType()`
`boolean`	`isSymbolValueType()`
`boolean`	`isTemplateType()`
`boolean`	`isTemplatizedType()`
`boolean`	`isUnionType()`
`boolean`	`isUnknownType()`
`boolean`	`isUnresolved()`
`boolean`	`isUnresolvedOrResolvedUnknown()`
`boolean`	`isUnsuccessfullyResolved()` Returns whether the type has undergone resolution and resolved to a "useless" type.
`boolean`	`isVoidable()` Tests whether this type is voidable.
`boolean`	`isVoidType()`
`boolean`	`loosenTypecheckingDueToForwardReferencedSupertype()` During type definition, was one of the supertypes of this type a forward reference?
`void`	`matchConstraint(JSType constraint)` Modify this type so that it matches the specified type.
`boolean`	`matchesNumberContext()` This predicate is used to test whether a given type can appear in a numeric context, such as an operand of a multiply operator.
`boolean`	`matchesObjectContext()` This predicate is used to test whether a given type can appear in an `Object` context, such as the expression in a with statement.
`boolean`	`matchesStringContext()` This predicate is used to test whether a given type can appear in a `String` context, such as an operand of a string concat (+) operator.
`boolean`	`matchesSymbolContext()` This predicate is used to test whether a given type can appear in a `symbol` context such as property access.
`void`	`mergeSupertypeTemplateTypes(ObjectType other)` Prepends the template type map associated with this type, merging in the keys and values of the specified map.
`JSType`	`resolve(ErrorReporter reporter)` Resolve this type in the given scope.
`JSType`	`restrictByNotNull()` If this is a union type, returns a union type that does not include the null type.
`JSType`	`restrictByNotNullOrUndefined()` If this is a union type, returns a union type that does not include the null or undefined type.
`JSType`	`restrictByNotUndefined()` If this is a union type, returns a union type that does not include the undefined type.
`boolean`	`setValidator(com.google.common.base.Predicate<JSType> validator)` Certain types have constraints on them at resolution-time.
`TernaryValue`	`testForEquality(JSType that)` Compares `this` and `that`.
`java.lang.String`	`toAnnotationString(JSType.Nullability nullability)`
`EnumElementType`	`toMaybeEnumElementType()` Downcasts this to an EnumElementType, or returns null if this is not an EnumElementType.
`EnumType`	`toMaybeEnumType()` Downcasts this to an EnumType, or returns null if this is not an EnumType.
`FunctionType`	`toMaybeFunctionType()` Downcasts this to a FunctionType, or returns null if this is not a function.
`static FunctionType`	`toMaybeFunctionType(JSType type)` Null-safe version of toMaybeFunctionType().
`NamedType`	`toMaybeNamedType()`
`ObjectType`	`toMaybeObjectType()`
`RecordType`	`toMaybeRecordType()` Downcasts this to a RecordType, or returns null if this is not a RecordType.
`TemplateType`	`toMaybeTemplateType()` Downcasts this to a TemplateType, or returns null if this is not a function.
`TemplatizedType`	`toMaybeTemplatizedType()` Downcasts this to a TemplatizedType, or returns null if this is not a function.
`UnionType`	`toMaybeUnionType()` Downcasts this to a UnionType, or returns null if this is not a UnionType.
`ObjectType`	`toObjectType()` Casts this to an ObjectType, or returns null if this is not an ObjectType.
`java.lang.String`	`toString()` A string representation of this type, suitable for printing in warnings.
`JSType`	`unboxesTo()` Turn an object type to its corresponding scalar type.
`abstract <T> T`	`visit(Visitor<T> visitor)` Visit this type with the given visitor.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - templateTypeMap
```
protected TemplateTypeMap templateTypeMap
```
- Method Detail
  - areIdentical
```
public static final boolean areIdentical(JSType a,
                                         JSType b)
```
  - getJSDocInfo
```
public JSDocInfo getJSDocInfo()
```
    Gets the docInfo for this type. By default, documentation cannot be attached to arbitrary types. This must be overridden for programmer-defined types.
  - getDisplayName
```
public java.lang.String getDisplayName()
```
    Returns a user meaningful label for the JSType instance. For example, Functions and Enums will return their declaration name (if they have one). Some types will not have a meaningful display name. Calls to hasDisplayName() will return true IFF getDisplayName() will return null or a zero length string.
    
    Returns:
    
    the display name of the type, or null if one is not available
  - hasDisplayName
```
public boolean hasDisplayName()
```
    Returns:
    
    true if the JSType has a user meaningful label.
  - getPropertyKind
```
public JSType.HasPropertyKind getPropertyKind(java.lang.String pname)
```
    Checks whether the property is present on the object.
    
    Parameters:
    
    pname - The property name.
  - getPropertyKind
```
public JSType.HasPropertyKind getPropertyKind(java.lang.String pname,
                                              boolean autobox)
```
    Checks whether the property is present on the object.
    
    Parameters:
    
    pname - The property name.
    
    autobox - Whether to check for the presents on an autoboxed type
  - hasProperty
```
public final boolean hasProperty(java.lang.String pname)
```
    Checks whether the property is present on the object.
    
    Parameters:
    
    pname - The property name.
  - isNoType
```
public boolean isNoType()
```
  - isNoResolvedType
```
public boolean isNoResolvedType()
```
  - isUnresolved
```
public final boolean isUnresolved()
```
  - isUnresolvedOrResolvedUnknown
```
public final boolean isUnresolvedOrResolvedUnknown()
```
  - isNoObjectType
```
public boolean isNoObjectType()
```
  - isEmptyType
```
public final boolean isEmptyType()
```
  - isNumberObjectType
```
public boolean isNumberObjectType()
```
  - isNumberValueType
```
public boolean isNumberValueType()
```
  - isFunctionPrototypeType
```
public boolean isFunctionPrototypeType()
```
    Whether this is the prototype of a function.
  - isStringObjectType
```
public boolean isStringObjectType()
```
  - isSymbolObjectType
```
public boolean isSymbolObjectType()
```
  - isStringValueType
```
public boolean isStringValueType()
```
  - isSymbolValueType
```
public boolean isSymbolValueType()
```
  - isString
```
public final boolean isString()
```
    Tests whether the type is a string (value or Object).
    
    Returns:
    
    this <: (String, string)
  - isNumber
```
public final boolean isNumber()
```
    Tests whether the type is a number (value or Object).
    
    Returns:
    
    this <: (Number, number)
  - isSymbol
```
public final boolean isSymbol()
```
  - isArrayType
```
public boolean isArrayType()
```
  - isBooleanObjectType
```
public boolean isBooleanObjectType()
```
  - isBooleanValueType
```
public boolean isBooleanValueType()
```
  - isRegexpType
```
public boolean isRegexpType()
```
  - isDateType
```
public boolean isDateType()
```
  - isNullType
```
public boolean isNullType()
```
  - isVoidType
```
public boolean isVoidType()
```
  - isAllType
```
public boolean isAllType()
```
  - isUnknownType
```
public boolean isUnknownType()
```
  - isSomeUnknownType
```
public final boolean isSomeUnknownType()
```
  - isCheckedUnknownType
```
public boolean isCheckedUnknownType()
```
  - isUnionType
```
public final boolean isUnionType()
```
  - isRawTypeOfTemplatizedType
```
public final boolean isRawTypeOfTemplatizedType()
```
  - isStruct
```
public boolean isStruct()
```
    Returns true iff this can be a struct. UnionType overrides the method, assume this is not a union here.
  - isDict
```
public boolean isDict()
```
    Returns true iff this can be a dict. UnionType overrides the method, assume this is not a union here.
  - containsReferenceAncestor
```
public final boolean containsReferenceAncestor(JSType target)
```
    This function searchers for a type `target` in the reference chain of ProxyObjectTypes
  - isLiteralObject
```
public final boolean isLiteralObject()
```
  - getGreatestSubtypeWithProperty
```
public JSType getGreatestSubtypeWithProperty(java.lang.String propName)
```
  - toMaybeUnionType
```
public UnionType toMaybeUnionType()
```
    Downcasts this to a UnionType, or returns null if this is not a UnionType. Named in honor of Haskell's Maybe type constructor.
  - isGlobalThisType
```
public final boolean isGlobalThisType()
```
    Returns true if this is a global this type.
  - isFunctionType
```
public final boolean isFunctionType()
```
    Returns true if toMaybeFunctionType returns a non-null FunctionType.
  - toMaybeFunctionType
```
public FunctionType toMaybeFunctionType()
```
    Downcasts this to a FunctionType, or returns null if this is not a function.
    For the purposes of this function, we define a MaybeFunctionType as any type in the sub-lattice { x | LEAST_FUNCTION_TYPE <= x <= GREATEST_FUNCTION_TYPE } This definition excludes bottom types like NoType and NoObjectType.
    This definition is somewhat arbitrary and axiomatic, but this is the definition that makes the most sense for the most callers.
  - assertFunctionType
```
public FunctionType assertFunctionType()
```
    Returns this object cast to FunctionType or throws an exception if it isn't a FunctionType.
  - assertObjectType
```
public ObjectType assertObjectType()
```
    Returns this object cast to ObjectType or throws an exception if it isn't an ObjectType.
  - toMaybeFunctionType
```
public static FunctionType toMaybeFunctionType(JSType type)
```
    Null-safe version of toMaybeFunctionType().
  - isEnumElementType
```
public final boolean isEnumElementType()
```
  - getEnumeratedTypeOfEnumElement
```
public final JSType getEnumeratedTypeOfEnumElement()
```
  - toMaybeEnumElementType
```
public EnumElementType toMaybeEnumElementType()
```
    Downcasts this to an EnumElementType, or returns null if this is not an EnumElementType.
  - isEnumType
```
public boolean isEnumType()
```
  - toMaybeEnumType
```
public EnumType toMaybeEnumType()
```
    Downcasts this to an EnumType, or returns null if this is not an EnumType.
  - isNamedType
```
public boolean isNamedType()
```
  - toMaybeNamedType
```
public NamedType toMaybeNamedType()
```
  - isRecordType
```
public boolean isRecordType()
```
  - isStructuralInterface
```
public boolean isStructuralInterface()
```
  - isStructuralType
```
public boolean isStructuralType()
```
  - toMaybeRecordType
```
public RecordType toMaybeRecordType()
```
    Downcasts this to a RecordType, or returns null if this is not a RecordType.
  - isTemplatizedType
```
public final boolean isTemplatizedType()
```
  - toMaybeTemplatizedType
```
public TemplatizedType toMaybeTemplatizedType()
```
    Downcasts this to a TemplatizedType, or returns null if this is not a function.
  - isTemplateType
```
public final boolean isTemplateType()
```
  - toMaybeTemplateType
```
public TemplateType toMaybeTemplateType()
```
    Downcasts this to a TemplateType, or returns null if this is not a function.
  - hasAnyTemplateTypes
```
public boolean hasAnyTemplateTypes()
```
  - getTemplateTypeMap
```
public TemplateTypeMap getTemplateTypeMap()
```
    Returns the template type map associated with this type.
  - getTypeParameters
```
public final com.google.common.collect.ImmutableList<TemplateType> getTypeParameters()
```
    Return, in order, the sequence of type parameters declared for this type.
    In general, this value corresponds to an element for every `@template` declaration on the type definition. It does not include template parameters from superclasses or superinterfaces.
  - getTemplateParamCount
```
public int getTemplateParamCount()
```
    Return the number of template parameters declared for this type.
    In general, this value corresponds to the number of `@template` declarations on the type definition. It does not include template parameters from superclasses or superinterfaces.
  - mergeSupertypeTemplateTypes
```
public void mergeSupertypeTemplateTypes(ObjectType other)
```
    Prepends the template type map associated with this type, merging in the keys and values of the specified map.
  - isObject
```
public boolean isObject()
```
    Tests whether this type is an Object, or any subtype thereof.
    
    Returns:
    
    this <: Object
  - isObjectType
```
public final boolean isObjectType()
```
    Tests whether this type is an Object, or any subtype thereof.
    
    Returns:
    
    this <: Object
  - isConstructor
```
public boolean isConstructor()
```
    Whether this type is a FunctionType that is a constructor or a named type that points to such a type.
  - isNominalType
```
public boolean isNominalType()
```
    Whether this type is a nominal type (a named instance object or a named enum).
  - isNominalConstructor
```
public final boolean isNominalConstructor()
```
    Whether this type is the original constructor of a nominal type. Does not include structural constructors.
  - isNativeObjectType
```
public boolean isNativeObjectType()
```
  - loosenTypecheckingDueToForwardReferencedSupertype
```
public boolean loosenTypecheckingDueToForwardReferencedSupertype()
```
    During type definition, was one of the supertypes of this type a forward reference?
    This is a hack to work around the fact that inheritance chains and template types aren't wired up correctly when this happens, which causes various false positives in checks. The known bugs associated are b/145145406, b/144327372, and b/132980305.
    This method should only be used to suppress potential false positives caused by one of the above bugs, in the case where we think suppressing typechecking is preferable to emitting a false positive.
  - isInstanceType
```
public boolean isInstanceType()
```
    Whether this type is an Instance object of some constructor. Does not necessarily mean this is an InstanceObjectType.
  - isInterface
```
public boolean isInterface()
```
    Whether this type is a FunctionType that is an interface or a named type that points to such a type.
  - isOrdinaryFunction
```
public boolean isOrdinaryFunction()
```
    Whether this type is a FunctionType that is an ordinary function (i.e. not a constructor, nominal interface, or record interface), or a named type that points to such a type.
  - equals
```
public final boolean equals(@Nullable
                            java.lang.Object other)
```
    Overrides:
    
    equals in class java.lang.Object
  - differsFrom
```
public final boolean differsFrom(JSType that)
```
    Whether this type is meaningfully different from that type for the purposes of data flow analysis.
    This is a trickier check than pure equality, because it has to properly handle unknown types. See EqMethod for more info.
  - hashCode
```
public final int hashCode()
```
    Calculates a hash of the object as per Object.hashCode().
    This method is unsafe for multi-threaded use. The implementation mutates instance state to prevent recursion and therefore expects sole access.
    
    Overrides:
    
    hashCode in class java.lang.Object
  - matchesNumberContext
```
public boolean matchesNumberContext()
```
    This predicate is used to test whether a given type can appear in a numeric context, such as an operand of a multiply operator.
  - matchesStringContext
```
public boolean matchesStringContext()
```
    This predicate is used to test whether a given type can appear in a String context, such as an operand of a string concat (+) operator. All types have at least the potential for converting to String. When we add externally defined types, such as a browser OM, we may choose to add types that do not automatically convert to String.
  - matchesSymbolContext
```
public boolean matchesSymbolContext()
```
    This predicate is used to test whether a given type can appear in a symbol context such as property access.
  - matchesObjectContext
```
public boolean matchesObjectContext()
```
    This predicate is used to test whether a given type can appear in an Object context, such as the expression in a with statement. Most types we will encounter, except notably null, have at least the potential for converting to Object. Host defined objects can get peculiar.
  - findPropertyType
```
@Nullable
public final JSType findPropertyType(java.lang.String propertyName)
```
    Coerces this type to an Object type, then gets the type of the property whose name is given.
    Unlike ObjectType.getPropertyType(java.lang.String), returns null if the property is not found.
    
    Returns:
    
    The property's type. null if the current type cannot have properties, or if the type is not found.
  - findPropertyTypeWithoutConsideringTemplateTypes
```
@ForOverride
 @Nullable
protected JSType findPropertyTypeWithoutConsideringTemplateTypes(java.lang.String propertyName)
```
    Looks up a property on this type, but without properly replacing any templates in the result.
    Subclasses can override this if they need more complicated logic for property lookup than just autoboxing to an object.
    This is only for use by findPropertyType(JSType). Call that method instead if you need to lookup a property on a random JSType
  - canBeCalled
```
public boolean canBeCalled()
```
    This predicate is used to test whether a given type can be used as the 'function' in a function call.
    
    Returns:
    
    true if this type might be callable.
  - canCastTo
```
public final boolean canCastTo(JSType that)
```
    Tests whether values of this type can be safely assigned to values of that type.
    The default implementation verifies that this is a subtype of that.
  - autoboxesTo
```
public JSType autoboxesTo()
```
    Turn a scalar type to the corresponding object type.
    
    Returns:
    
    the auto-boxed type or null if this type is not a scalar.
  - isBoxableScalar
```
public boolean isBoxableScalar()
```
  - unboxesTo
```
public JSType unboxesTo()
```
    Turn an object type to its corresponding scalar type.
    
    Returns:
    
    the unboxed type or null if this type does not unbox.
  - toObjectType
```
public ObjectType toObjectType()
```
    Casts this to an ObjectType, or returns null if this is not an ObjectType. If this is a scalar type, it will *not* be converted to an object type. If you want to simulate JS autoboxing or dereferencing, you should use autoboxesTo() or dereference().
  - autobox
```
public JSType autobox()
```
    Dereferences a type for property access. Filters null/undefined and autoboxes the resulting type. Never returns null.
  - dereference
```
@Nullable
public final ObjectType dereference()
```
    Dereferences a type for property access. Filters null/undefined, autoboxes the resulting type, and returns it iff it's an object. If not an object, returns null.
  - canTestForEqualityWith
```
public final boolean canTestForEqualityWith(JSType that)
```
    Tests whether this and that are meaningfully comparable. By meaningfully, we mean compatible types that do not lead to step 22 of the definition of the Abstract Equality Comparison Algorithm (11.9.3, page 55–56) of the ECMA-262 specification.
  - testForEquality
```
public TernaryValue testForEquality(JSType that)
```
    Compares this and that.
    Returns:
    TernaryValue.TRUE if the comparison of values of this type and that always succeed (such as undefined compared to null)
    
    TernaryValue.FALSE if the comparison of values of this type and that always fails (such as undefined compared to number)
    
    TernaryValue.UNKNOWN if the comparison can succeed or fail depending on the concrete values
  - canTestForShallowEqualityWith
```
public final boolean canTestForShallowEqualityWith(JSType that)
```
    Tests whether this and that are meaningfully comparable using shallow comparison. By meaningfully, we mean compatible types that are not rejected by step 1 of the definition of the Strict Equality Comparison Algorithm (11.9.6, page 56–57) of the ECMA-262 specification.
  - isNullable
```
public boolean isNullable()
```
    Tests whether this type is nullable.
  - isVoidable
```
public boolean isVoidable()
```
    Tests whether this type is voidable.
  - isExplicitlyVoidable
```
public boolean isExplicitlyVoidable()
```
    Tests whether this type explicitly allows undefined, as opposed to ? or *. This is required for a property to be optional.
  - collapseUnion
```
public JSType collapseUnion()
```
    Gets the least supertype of this that's not a union.
  - getLeastSupertype
```
public JSType getLeastSupertype(JSType that)
```
    Gets the least supertype of this and that. The least supertype is the join (∨) or supremum of both types in the type lattice.
    Examples:
    - number ∨ * = *
    - number ∨ Object = (number, Object)
    - Number ∨ Object = Object
    Returns:
    
    this ∨ that
  - getGreatestSubtype
```
public JSType getGreatestSubtype(JSType that)
```
    Gets the greatest subtype of this and that. The greatest subtype is the meet (∧) or infimum of both types in the type lattice.
    Examples
    - Number ∧ Any = Any
    - number ∧ Object = Any
    - Number ∧ Object = Number
    Returns:
    
    this ∨ that
  - getRestrictedTypeGivenOutcome
```
public JSType getRestrictedTypeGivenOutcome(Outcome outcome)
```
    Computes the restricted type of this type knowing that the ToBoolean predicate has a specific value. For more information about the ToBoolean predicate, see getPossibleToBooleanOutcomes().
    
    Parameters:
    
    outcome - the value of the ToBoolean predicate
    
    Returns:
    
    the restricted type, or the Any Type if the underlying type could not have yielded this ToBoolean value TODO(user): Move this method to the SemanticRAI and use the visit method of types to get the restricted type.
  - getPossibleToBooleanOutcomes
```
public abstract BooleanLiteralSet getPossibleToBooleanOutcomes()
```
    Computes the set of possible outcomes of the ToBoolean predicate for this type. The ToBoolean predicate is defined by the ECMA-262 standard, 3^rd edition. Its behavior for simple types can be summarized by the following table:
    ToBoolean results by input type
    type result
    
    undefined {false}
    
    null {false}
    
    boolean {true, false}
    
    number {true, false}
    
    string {true, false}
    
    Object {true}
    
    Returns:
    
    the set of boolean literals for this type
  - getTypesUnderEquality
```
public JSType.TypePair getTypesUnderEquality(JSType that)
```
    Computes the subset of this and that types if equality is observed. If a value v1 of type null is equal to a value v2 of type (undefined,number), we can infer that the type of v1 is null and the type of v2 is undefined.
    
    Returns:
    
    a pair containing the restricted type of this as the first component and the restricted type of that as the second element. The returned pair is never null even though its components may be null
  - getTypesUnderInequality
```
public JSType.TypePair getTypesUnderInequality(JSType that)
```
    Computes the subset of this and that types if inequality is observed. If a value v1 of type number is not equal to a value v2 of type (undefined,number), we can infer that the type of v1 is number and the type of v2 is number as well.
    
    Returns:
    
    a pair containing the restricted type of this as the first component and the restricted type of that as the second element. The returned pair is never null even though its components may be null
  - getTypesUnderShallowEquality
```
public JSType.TypePair getTypesUnderShallowEquality(JSType that)
```
    Computes the subset of this and that types under shallow equality.
    
    Returns:
    
    a pair containing the restricted type of this as the first component and the restricted type of that as the second element. The returned pair is never null even though its components may be null.
  - getTypesUnderShallowInequality
```
public JSType.TypePair getTypesUnderShallowInequality(JSType that)
```
    Computes the subset of this and that types under shallow inequality.
    
    Returns:
    
    A pair containing the restricted type of this as the first component and the restricted type of that as the second element. The returned pair is never null even though its components may be null
  - getUnionMembers
```
public java.lang.Iterable<JSType> getUnionMembers()
```
  - restrictByNotNullOrUndefined
```
public JSType restrictByNotNullOrUndefined()
```
    If this is a union type, returns a union type that does not include the null or undefined type.
  - restrictByNotUndefined
```
public JSType restrictByNotUndefined()
```
    If this is a union type, returns a union type that does not include the undefined type.
  - restrictByNotNull
```
public JSType restrictByNotNull()
```
    If this is a union type, returns a union type that does not include the null type.
  - isSubtypeWithoutStructuralTyping
```
public final boolean isSubtypeWithoutStructuralTyping(JSType supertype)
```
    the logic of this method is similar to isSubtype, except that it does not perform structural interface matching
    This function is added for disambiguate properties, and is deprecated for the other use cases.
  - isSubtype
```
public final boolean isSubtype(JSType supertype)
```
    Checks whether this is a subtype of that.
    Note this function also returns true if this type structurally matches the protocol define by that type (if that type is an interface function type)
    Subtyping rules:
    - (unknown) — every type is a subtype of the Unknown type.
    - (no) — the No type is a subtype of every type.
    - (no-object) — the NoObject type is a subtype of every object type (i.e. subtypes of the Object type).
    - (ref) — a type is a subtype of itself.
    - (union-l) — A union type is a subtype of a type U if all the union type's constituents are a subtype of U. Formally
      (T₁, …, T_n) <: U if and only T_k <: U for all k ∈ 1..n.
    - (union-r) — A type U is a subtype of a union type if it is a subtype of one of the union type's constituents. Formally
      U <: (T₁, …, T_n) if and only if U <: T_k for some index k.
    - (objects) — an Object O₁ is a subtype of an object O₂ if it has more properties than O₂ and all common properties are pairwise subtypes.
    Returns:
    
    this <: that
  - isSubtype
```
@Deprecated
public final boolean isSubtype(JSType supertype,
                                           JSType.SubtypingMode mode)
```
    Deprecated. Prefer isSubtype(JSType) instead.
  - isSubtypeOf
```
public final boolean isSubtypeOf(JSType supertype)
```
  - isSubtypeOf
```
public final boolean isSubtypeOf(JSType supertype,
                                 JSType.SubtypingMode mode)
```
  - visit
```
public abstract <T> T visit(Visitor<T> visitor)
```
    Visit this type with the given visitor.
    
    Returns:
    
    the value returned by the visitor
    
    See Also:
    
    Visitor
  - resolve
```
public final JSType resolve(ErrorReporter reporter)
```
    Resolve this type in the given scope.
    The returned value must be equal to this, as defined by equals(java.lang.Object). It may or may not be the same object. This method may modify the internal state of this, as long as it does so in a way that preserves Object equality.
    For efficiency, we should only resolve a type once per compilation job. For incremental compilations, one compilation job may need the artifacts from a previous generation, so we will eventually need a generational flag instead of a boolean one.
  - isResolved
```
public final boolean isResolved()
```
    Returns whether the type has undergone resolution.
    A value of true does not indicate that resolution was successful, only that it was attempted and has finished.
  - isSuccessfullyResolved
```
public final boolean isSuccessfullyResolved()
```
    Returns whether the type has undergone resolution and resolved to a "useful" type.
  - isUnsuccessfullyResolved
```
public final boolean isUnsuccessfullyResolved()
```
    Returns whether the type has undergone resolution and resolved to a "useless" type.
  - setValidator
```
public boolean setValidator(com.google.common.base.Predicate<JSType> validator)
```
    Certain types have constraints on them at resolution-time. For example, a type in an @extends annotation must be an object. Clients should inject a validator that emits a warning if the type does not validate, and return false.
  - toString
```
public java.lang.String toString()
```
    A string representation of this type, suitable for printing in warnings.
    
    Overrides:
    
    toString in class java.lang.Object
  - toAnnotationString
```
public final java.lang.String toAnnotationString(JSType.Nullability nullability)
```
  - matchConstraint
```
public void matchConstraint(JSType constraint)
```
    Modify this type so that it matches the specified type. This is useful for reverse type-inference, where we want to infer that an object literal matches its constraint (much like how the java compiler does reverse-inference to figure out generics).
    
    Parameters:
    
    constraint -
  - toMaybeObjectType
```
public ObjectType toMaybeObjectType()
```

type	result
`undefined`	{false}
`null`	{false}
`boolean`	{true, false}
`number`	{true, false}
`string`	{true, false}
`Object`	{true}

Class JSType

Nested Class Summary

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

templateTypeMap

Method Detail

areIdentical

getJSDocInfo

getDisplayName

hasDisplayName

getPropertyKind

getPropertyKind

hasProperty

isNoType

isNoResolvedType

isUnresolved

isUnresolvedOrResolvedUnknown

isNoObjectType

isEmptyType

isNumberObjectType

isNumberValueType

isFunctionPrototypeType

isStringObjectType

isSymbolObjectType

isStringValueType

isSymbolValueType

isString

isNumber

isSymbol

isArrayType

isBooleanObjectType

isBooleanValueType

isRegexpType

isDateType

isNullType

isVoidType

isAllType

isUnknownType

isSomeUnknownType

isCheckedUnknownType

isUnionType

isRawTypeOfTemplatizedType

isStruct

isDict

containsReferenceAncestor

isLiteralObject

getGreatestSubtypeWithProperty

toMaybeUnionType

isGlobalThisType

isFunctionType

toMaybeFunctionType

assertFunctionType

assertObjectType

toMaybeFunctionType

isEnumElementType

getEnumeratedTypeOfEnumElement

toMaybeEnumElementType

isEnumType

toMaybeEnumType

isNamedType

toMaybeNamedType

isRecordType

isStructuralInterface

isStructuralType

toMaybeRecordType

isTemplatizedType

toMaybeTemplatizedType

isTemplateType

toMaybeTemplateType

hasAnyTemplateTypes

getTemplateTypeMap

getTypeParameters

getTemplateParamCount

mergeSupertypeTemplateTypes

isObject

isObjectType

isConstructor

isNominalType