Class UnknownType

Method Details

• isUnknownType

  public boolean isUnknownType()

  Description copied from class: ObjectType

  We treat this as the unknown type if any of its implicit prototype properties is unknown.

  Overrides:

  isUnknownType in class ObjectType

• isCheckedUnknownType

  public boolean isCheckedUnknownType()

  Overrides:

  isCheckedUnknownType 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.

• 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

• testForEquality

  public TernaryValue testForEquality(JSType that)

  Description copied from class: JSType

  Compares this and that.

  Overrides:

  testForEquality in class ObjectType

  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()

  Description copied from class: JSType

  Tests whether this type is nullable.

  Overrides:

  isNullable in class JSType

• isSubtype

  public boolean isSubtype(JSType that)

  Description copied from class: JSType

  Checks whether this is a subtype of that.

  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
    (T<sub>1</sub>, &hellip;, T<sub>n</sub>) &lt;: U if and only T<sub>k</sub> &lt;: 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 &lt;: (T<sub>1</sub>, &hellip;, T<sub>n</sub>) if and only if U &lt;: T<sub>k</sub> for some index k.
  • (objects) — an Object O<sub>1</sub> is a subtype of an object O<sub>2</sub> if it has more properties than O<sub>2</sub> and all common properties are pairwise subtypes.

  Overrides:

  isSubtype in class JSType

  Returns:

  this <: that

• visit

  public <T> T visit(Visitor<T> visitor)

  Description copied from class: JSType

  Visit this type with the given visitor.

  Overrides:

  visit in class ObjectType

  Returns:

  the value returned by the visitor

  See Also:

  • Visitor

• getImplicitPrototype

  public ObjectType getImplicitPrototype()

  Description copied from class: ObjectType

  Gets the implicit prototype (a.k.a. the [[Prototype]] property).

  Specified by:

  getImplicitPrototype in class ObjectType

• getConstructor

  public FunctionType getConstructor()

  Description copied from class: ObjectType

  Gets this object's constructor.

  Specified by:

  getConstructor in class ObjectType

  Returns:

  this object's constructor or null if it is a native object (constructed natively v.s. by instantiation of a function)

• getReferenceName

  public String getReferenceName()

  Description copied from class: ObjectType

  Gets the reference name for this object. This includes named types like constructors, prototypes, and enums. It notably does not include literal types like strings and booleans and structural types.

  Specified by:

  getReferenceName in class ObjectType

  Returns:

  the object's name or null if this is an anonymous object

• 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 ObjectType

  Returns:

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

• hasDisplayName

  public boolean hasDisplayName()

  Overrides:

  hasDisplayName in class JSType

  Returns:

  true if the JSType has a user meaningful label.

• 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}

  Overrides:

  getPossibleToBooleanOutcomes in class ObjectType

  Returns:

  the set of boolean literals for this type