Package com.google.javascript.rhino.jstype

Class JSType

    • 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()

      • isBigIntObjectType

        public boolean isBigIntObjectType()

      • isBigIntValueType

        public boolean isBigIntValueType()

      • 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()

      • isBigIntOrNumber

        public final boolean isBigIntOrNumber()

      • isOnlyBigInt

        public final boolean isOnlyBigInt()
        Checks whether the type is a bigint and *only* a bigint (value or Object).

      • 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).

      • isNominalConstructorOrInterface

        public final boolean isNominalConstructorOrInterface()
        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, 3rd edition. Its behavior for simple types can be summarized by the following table:
        ToBoolean results by input type
        typeresult
        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 final 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, …, Tn) <: U if and only Tk <: 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, …, Tn) if and only if U <: Tk 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

      • isSubtypeOf

        public final boolean isSubtypeOf​(JSType supertype)

      • 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()