com.google.javascript.rhino.jstype

Class NullType

java.lang.Object

com.google.javascript.rhino.jstype.JSType

com.google.javascript.rhino.jstype.NullType

All Implemented Interfaces:

Serializable

public final class NullType
extends JSType

Null type.

See Also:

Serialized Form

Nested Class Summary

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

JSType.TypePair

Field Summary

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

EMPTY_TYPE_COMPONENT, ENUMDECL, NOT_A_CLASS, NOT_A_TYPE, NOT_ENUMDECL, templateTypeMap, UNKNOWN_NAME

Method Summary

Methods

Modifier and Type	Method and Description
String	getDisplayName() Returns a user meaningful label for the JSType instance.
BooleanLiteralSet	getPossibleToBooleanOutcomes() Computes the set of possible outcomes of the ToBoolean predicate for this type.
boolean	hasDisplayName()
boolean	isNullable() Tests whether this type is nullable.
boolean	isNullType()
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.
JSType	restrictByNotNullOrUndefined() If this is a union type, returns a union type that does not include the null or undefined type.
TernaryValue	testForEquality(JSType that) Compares this and that.
<T> T	visit(Visitor<T> visitor) Visit this type with the given visitor.

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

autobox, autoboxesTo, canBeCalled, canCastTo, canTestForEqualityWith, canTestForShallowEqualityWith, clearResolved, collapseUnion, dereference, differsFrom, equals, extendTemplateTypeMap, findPropertyType, getGreatestSubtype, getJSDocInfo, getLeastSupertype, getRestrictedTypeGivenToBooleanOutcome, getTemplateTypeMap, getTypesUnderEquality, getTypesUnderInequality, getTypesUnderShallowEquality, getTypesUnderShallowInequality, hasAnyTemplateTypes, hashCode, hasProperty, isAllType, isArrayType, isBooleanObjectType, isBooleanValueType, isCheckedUnknownType, isConstructor, isDateType, isDict, isEmptyType, isEnumElementType, isEnumType, isEquivalent, isEquivalentTo, isFunctionPrototypeType, isFunctionType, isGlobalThisType, isInstanceType, isInterface, isInvariant, isNominalConstructor, isNominalType, isNoObjectType, isNoResolvedType, isNoType, isNumber, isNumberObjectType, isNumberValueType, isObject, isOrdinaryFunction, isRecordType, isRegexpType, isResolved, isString, isStringObjectType, isStringValueType, isStruct, isSubtype, isTemplateType, isTemplatizedType, isUnionType, isUnknownType, isVoidType, matchConstraint, matchesInt32Context, matchesUint32Context, resolve, setValidator, toAnnotationString, toDebugHashCodeString, toMaybeEnumElementType, toMaybeEnumType, toMaybeFunctionType, toMaybeFunctionType, toMaybeTemplateType, toMaybeTemplateType, toMaybeTemplatizedType, toMaybeTemplatizedType, toMaybeUnionType, toObjectType, toString, unboxesTo

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

isNullType

public boolean isNullType()

Overrides:

isNullType in class JSType

isNullable

public boolean isNullable()

Description copied from class: JSType

Tests whether this type is nullable.

Overrides:

isNullable in class JSType

matchesNumberContext

public boolean matchesNumberContext()

Description copied from class: JSType

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

matchesObjectContext

public boolean matchesObjectContext()

Description copied from class: JSType

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.

Overrides:

matchesObjectContext in class JSType

matchesStringContext

public boolean matchesStringContext()

Description copied from class: JSType

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

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

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

getDisplayName

public String getDisplayName()

Description copied from class: JSType

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.

Overrides:

getDisplayName in class JSType

Returns:

the display name of the type, or null if one is not available

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:

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

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

hasDisplayName

public boolean hasDisplayName()

Overrides:

hasDisplayName in class JSType

Returns:

true if the JSType has a user meaningful label.