com.google.javascript.rhino.jstype
Class NullType

java.lang.Object
  extended by com.google.javascript.rhino.jstype.JSType
      extended by 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, UNKNOWN_NAME
 
Method Summary
 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, canAssignTo, canBeCalled, canTestForEqualityWith, canTestForShallowEqualityWith, clearResolved, collapseUnion, dereference, differsFrom, equals, findPropertyType, forceResolve, getGreatestSubtype, getJSDocInfo, getLeastSupertype, getRestrictedTypeGivenToBooleanOutcome, getTypesUnderEquality, getTypesUnderInequality, getTypesUnderShallowEquality, getTypesUnderShallowInequality, hashCode, isAllType, isArrayType, isBooleanObjectType, isBooleanValueType, isCheckedUnknownType, isConstructor, isDateType, isEmptyType, isEnumElementType, isEnumType, isEquivalent, isEquivalentTo, isFunctionPrototypeType, isFunctionType, isGlobalThisType, isInstanceType, isInterface, isNominalConstructor, isNominalType, isNoObjectType, isNoResolvedType, isNoType, isNumber, isNumberObjectType, isNumberValueType, isObject, isOrdinaryFunction, isRecordType, isRegexpType, isResolved, isString, isStringObjectType, isStringValueType, isSubtype, isTemplateType, isUnionType, isUnknownType, isVoidType, matchConstraint, matchesInt32Context, matchesUint32Context, resolve, setValidator, toAnnotationString, toDebugHashCodeString, toMaybeEnumElementType, toMaybeEnumType, toMaybeFunctionType, toMaybeFunctionType, 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, 3rd edition. Its behavior for simple types can be summarized by the following table:
typeresult
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.