UnionType (Closure Compiler v20191111 API)

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

All Implemented Interfaces:

java.io.Serializable
```
public class UnionType
extends JSType
```
A type that may be any one of a set of types, and thus has the intersection of the properties of those types.
The UnionType implements a common JavaScript idiom in which the code is specifically designed to work with multiple input types. Because JavaScript always knows the run-time type of an object value, this is safer than a C union.
For instance, values of the union type (String,boolean) can be of type String or of type boolean. The commutativity of the statement is captured by making (String,boolean) and (boolean,String) equal.
The implementation of this class prevents the creation of nested unions.

See Also:

Serialized Form

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`UnionType.Builder` Implements type unioning logic, since `UnionType`s only actually need to perform unioning operations when being (re)built.

Nested classes/interfaces inherited from class com.google.javascript.rhino.jstype.JSType
JSType.HasPropertyKind, JSType.Nullability, JSType.SubtypingMode, JSType.TypePair

Field Summary
- Fields inherited from class com.google.javascript.rhino.jstype.JSType
  templateTypeMap

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`JSType`	`autobox()` Dereferences a type for property access.
`static UnionType.Builder`	`builder(JSTypeRegistry registry)` Creates a `UnionType.Builder` for a new `UnionType`.
`boolean`	`canBeCalled()` This predicate is used to test whether a given type can be used as the 'function' in a function call.
`JSType`	`collapseUnion()` Gets the least supertype of this that's not a union.
`boolean`	`contains(JSType type)` A `UnionType` contains a given type (alternate) iff the member vector contains it.
`protected JSType`	`findPropertyTypeWithoutConsideringTemplateTypes(java.lang.String propertyName)` Looks up a property on this type, but without properly replacing any templates in the result.
`com.google.common.collect.ImmutableList<JSType>`	`getAlternates()` Gets the alternate types of this union type.
`JSType`	`getLeastSupertype(JSType that)` Gets the least supertype of `this` and `that`.
`BooleanLiteralSet`	`getPossibleToBooleanOutcomes()` Computes the set of possible outcomes of the `ToBoolean` predicate for this type.
`JSType.HasPropertyKind`	`getPropertyKind(java.lang.String pname, boolean autobox)` Checks whether the property is present on the object.
`JSType`	`getRestrictedTypeGivenToBooleanOutcome(boolean outcome)` Computes the restricted type of this type knowing that the `ToBoolean` predicate has a specific value.
`JSType`	`getRestrictedUnion(JSType type)` Returns a more restricted union type than `this` one, in which all subtypes of `type` have been removed.
`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`	`getTypesUnderShallowInequality(JSType that)` Computes the subset of `this` and `that` types under shallow inequality.
`boolean`	`hasAnyTemplateTypesInternal()`
`boolean`	`isDict()` Returns true iff `this` can be a `dict`.
`boolean`	`isExplicitlyVoidable()` Tests whether this type explicitly allows undefined (as opposed to ? or *).
`boolean`	`isNullable()` This predicate determines whether objects of this type can have the `null` value, and therefore can appear in contexts where `null` is expected.
`boolean`	`isObject()` Tests whether this type is an `Object`, or any subtype thereof.
`boolean`	`isStruct()` Returns true iff `this` can be a `struct`.
`boolean`	`isUnknownType()`
`boolean`	`isVoidable()` Tests whether this type is voidable.
`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
`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`	`toDebugHashCodeString()` A hash code function for diagnosing complicated issues around type-identity.
`UnionType`	`toMaybeUnionType()` Downcasts this to a UnionType, or returns null if this is not a UnionType.
`<T> T`	`visit(Visitor<T> visitor)` Visit this type with the given visitor.

Methods inherited from class com.google.javascript.rhino.jstype.JSType
assertFunctionType, assertObjectType, autoboxesTo, canCastTo, canTestForEqualityWith, canTestForShallowEqualityWith, containsReferenceAncestor, dereference, differsFrom, equals, findPropertyType, getDisplayName, getEnumeratedTypeOfEnumElement, getGreatestSubtype, getGreatestSubtypeWithProperty, getJSDocInfo, getPropertyKind, getTemplateParamCount, getTemplateTypeMap, getTypeParameters, getTypesUnderShallowEquality, getUnionMembers, hasAnyTemplateTypes, hasDisplayName, hashCode, hasProperty, isAllType, isArrayType, isBooleanObjectType, isBooleanValueType, isBoxableScalar, isCheckedUnknownType, isConstructor, isDateType, isEmptyType, isEnumElementType, isEnumType, isEquivalent, isEquivalentTo, isEquivalentTo, isFunctionPrototypeType, isFunctionType, isGlobalThisType, isInstanceType, isInterface, isLiteralObject, isNamedType, isNativeObjectType, isNominalConstructor, isNominalType, isNoObjectType, isNoResolvedType, isNoType, isNullType, isNumber, isNumberObjectType, isNumberValueType, isObjectType, isOrdinaryFunction, isRawTypeOfTemplatizedType, isRecordType, isRegexpType, isResolved, isSomeUnknownType, isString, isStringObjectType, isStringValueType, isStructuralInterface, isStructuralType, isSubtype, isSubtype, isSubtypeOf, isSubtypeOf, isSubtypeWithoutStructuralTyping, isSuccessfullyResolved, isSymbol, isSymbolObjectType, isSymbolValueType, isTemplateType, isTemplatizedType, isTypeVariable, isUnionType, isUnresolved, isUnresolvedOrResolvedUnknown, isUnsuccessfullyResolved, isVoidType, mergeSupertypeTemplateTypes, resolve, toAnnotationString, toMaybeEnumElementType, toMaybeEnumType, toMaybeFunctionType, toMaybeFunctionType, toMaybeNamedType, toMaybeObjectType, toMaybeRecordType, toMaybeTemplateType, toMaybeTemplatizedType, toObjectType, toString, unboxesTo

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

- Method Detail
  - builder
```
public static UnionType.Builder builder(JSTypeRegistry registry)
```
    Creates a UnionType.Builder for a new UnionType.
  - getAlternates
```
public com.google.common.collect.ImmutableList<JSType> getAlternates()
```
    Gets the alternate types of this union type.
    
    Returns:
    
    The alternate types of this union type. The returned set is immutable.
  - 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.
    
    Overrides:
    
    matchesNumberContext in class JSType
    
    Returns:
    
    true if the type can appear in a numeric context.
  - 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.
    
    Overrides:
    
    matchesStringContext in class JSType
    
    Returns:
    
    true if not VoidType
  - matchesSymbolContext
```
public boolean matchesSymbolContext()
```
    This predicate is used to test whether a given type can appear in a Symbol context
    
    Overrides:
    
    matchesSymbolContext in class JSType
    
    Returns:
    
    true if not it maybe a symbol or Symbol object
  - 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.
    VOID type is included here because while it is not part of the JavaScript language, functions returning 'void' type can't be used as operands of any operator or statement.
    
    Overrides:
    
    matchesObjectContext in class JSType
    
    Returns:
    
    true if the type is not NullType or VoidType
  - findPropertyTypeWithoutConsideringTemplateTypes
```
protected JSType findPropertyTypeWithoutConsideringTemplateTypes(java.lang.String propertyName)
```
    Description copied from class: JSType
    
    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
    
    Overrides:
    
    findPropertyTypeWithoutConsideringTemplateTypes in class JSType
  - canBeCalled
```
public boolean canBeCalled()
```
    Description copied from class: JSType
    
    This predicate is used to test whether a given type can be used as the 'function' in a function call.
    
    Overrides:
    
    canBeCalled in class JSType
    
    Returns:
    
    true if this type might be callable.
  - autobox
```
public JSType autobox()
```
    Description copied from class: JSType
    
    Dereferences a type for property access. Filters null/undefined and autoboxes the resulting type. Never returns null.
    
    Overrides:
    
    autobox in class JSType
  - restrictByNotNullOrUndefined
```
public JSType restrictByNotNullOrUndefined()
```
    Description copied from class: JSType
    
    If this is a union type, returns a union type that does not include the null or undefined type.
    
    Overrides:
    
    restrictByNotNullOrUndefined in class JSType
  - restrictByNotUndefined
```
public JSType restrictByNotUndefined()
```
    Description copied from class: JSType
    
    If this is a union type, returns a union type that does not include the undefined type.
    
    Overrides:
    
    restrictByNotUndefined in class JSType
  - restrictByNotNull
```
public JSType restrictByNotNull()
```
    Description copied from class: JSType
    
    If this is a union type, returns a union type that does not include the null type.
    
    Overrides:
    
    restrictByNotNull in class JSType
  - testForEquality
```
public TernaryValue testForEquality(JSType that)
```
    Description copied from class: JSType
    
    Compares this and that.
    Overrides:
    
    testForEquality in class JSType
    
    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
  - isNullable
```
public boolean isNullable()
```
    This predicate determines whether objects of this type can have the null value, and therefore can appear in contexts where null is expected.
    
    Overrides:
    
    isNullable in class JSType
    
    Returns:
    
    true for everything but Number and Boolean types.
  - isVoidable
```
public boolean isVoidable()
```
    Tests whether this type is voidable.
    
    Overrides:
    
    isVoidable in class JSType
  - isExplicitlyVoidable
```
public boolean isExplicitlyVoidable()
```
    Tests whether this type explicitly allows undefined (as opposed to ? or *).
    
    Overrides:
    
    isExplicitlyVoidable in class JSType
  - isUnknownType
```
public boolean isUnknownType()
```
    Overrides:
    
    isUnknownType in class JSType
  - isStruct
```
public boolean isStruct()
```
    Description copied from class: JSType
    
    Returns true iff this can be a struct. UnionType overrides the method, assume this is not a union here.
    
    Overrides:
    
    isStruct in class JSType
  - isDict
```
public boolean isDict()
```
    Description copied from class: JSType
    
    Returns true iff this can be a dict. UnionType overrides the method, assume this is not a union here.
    
    Overrides:
    
    isDict in class JSType
  - getLeastSupertype
```
public JSType getLeastSupertype(JSType that)
```
    Description copied from class: JSType
    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
    Overrides:
    
    getLeastSupertype in class JSType
    
    Returns:
    
    this ∨ that
  - getPropertyKind
```
public JSType.HasPropertyKind getPropertyKind(java.lang.String pname,
                                              boolean autobox)
```
    Description copied from class: JSType
    
    Checks whether the property is present on the object.
    
    Overrides:
    
    getPropertyKind in class JSType
    
    Parameters:
    
    pname - The property name.
    
    autobox - Whether to check for the presents on an autoboxed type
  - toMaybeUnionType
```
public UnionType toMaybeUnionType()
```
    Description copied from class: JSType
    
    Downcasts this to a UnionType, or returns null if this is not a UnionType. Named in honor of Haskell's Maybe type constructor.
    
    Overrides:
    
    toMaybeUnionType in class JSType
  - isObject
```
public boolean isObject()
```
    Description copied from class: JSType
    
    Tests whether this type is an Object, or any subtype thereof.
    
    Overrides:
    
    isObject in class JSType
    
    Returns:
    
    this <: Object
  - contains
```
public boolean contains(JSType type)
```
    A UnionType contains a given type (alternate) iff the member vector contains it.
    
    Parameters:
    
    type - The alternate which might be in this union.
    
    Returns:
    
    true if the alternate is in the union
  - getRestrictedUnion
```
public JSType getRestrictedUnion(JSType type)
```
    Returns a more restricted union type than this one, in which all subtypes of type have been removed.
    Examples:
    - (number,string) restricted by number is string
    - (null, EvalError, URIError) restricted by Error is null
    Parameters:
    
    type - the supertype of the types to remove from this union type
  - getRestrictedTypeGivenToBooleanOutcome
```
public JSType getRestrictedTypeGivenToBooleanOutcome(boolean outcome)
```
    Description copied from class: JSType
    
    Computes the restricted type of this type knowing that the ToBoolean predicate has a specific value. For more information about the ToBoolean predicate, see JSType.getPossibleToBooleanOutcomes().
    
    Overrides:
    
    getRestrictedTypeGivenToBooleanOutcome in class JSType
    
    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 BooleanLiteralSet getPossibleToBooleanOutcomes()
```
    Description copied from class: JSType
    
    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}
    
    Specified by:
    
    getPossibleToBooleanOutcomes in class JSType
    
    Returns:
    
    the set of boolean literals for this type
  - getTypesUnderEquality
```
public JSType.TypePair getTypesUnderEquality(JSType that)
```
    Description copied from class: JSType
    
    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.
    
    Overrides:
    
    getTypesUnderEquality in class JSType
    
    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)
```
    Description copied from class: JSType
    
    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.
    
    Overrides:
    
    getTypesUnderInequality in class JSType
    
    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)
```
    Description copied from class: JSType
    
    Computes the subset of this and that types under shallow inequality.
    
    Overrides:
    
    getTypesUnderShallowInequality in class JSType
    
    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
  - visit
```
public <T> T visit(Visitor<T> visitor)
```
    Description copied from class: JSType
    
    Visit this type with the given visitor.
    
    Specified by:
    
    visit in class JSType
    
    Returns:
    
    the value returned by the visitor
    
    See Also:
    
    Visitor
  - toDebugHashCodeString
```
public java.lang.String toDebugHashCodeString()
```
    Description copied from class: JSType
    
    A hash code function for diagnosing complicated issues around type-identity.
    
    Overrides:
    
    toDebugHashCodeString in class JSType
  - setValidator
```
public boolean setValidator(com.google.common.base.Predicate<JSType> validator)
```
    Description copied from class: JSType
    
    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.
    
    Overrides:
    
    setValidator in class JSType
  - collapseUnion
```
public JSType collapseUnion()
```
    Description copied from class: JSType
    
    Gets the least supertype of this that's not a union.
    
    Overrides:
    
    collapseUnion in class JSType
  - matchConstraint
```
public void matchConstraint(JSType constraint)
```
    Description copied from class: JSType
    
    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).
    
    Overrides:
    
    matchConstraint in class JSType
  - hasAnyTemplateTypesInternal
```
public boolean hasAnyTemplateTypesInternal()
```

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

Class UnionType

Nested Class Summary

Nested classes/interfaces inherited from class com.google.javascript.rhino.jstype.JSType

Field Summary

Fields inherited from class com.google.javascript.rhino.jstype.JSType

Method Summary

Methods inherited from class com.google.javascript.rhino.jstype.JSType

Methods inherited from class java.lang.Object

Method Detail

builder

getAlternates

matchesNumberContext

matchesStringContext

matchesSymbolContext

matchesObjectContext

findPropertyTypeWithoutConsideringTemplateTypes

canBeCalled

autobox

restrictByNotNullOrUndefined

restrictByNotUndefined

restrictByNotNull

testForEquality

isNullable

isVoidable

isExplicitlyVoidable

isUnknownType

isStruct

isDict

getLeastSupertype

getPropertyKind

toMaybeUnionType

isObject

contains

getRestrictedUnion

getRestrictedTypeGivenToBooleanOutcome

getPossibleToBooleanOutcomes

getTypesUnderEquality

getTypesUnderInequality

getTypesUnderShallowInequality

visit

toDebugHashCodeString

setValidator

collapseUnion

matchConstraint

hasAnyTemplateTypesInternal