SwitchBootstraps

open class SwitchBootstraps
kotlin.Any
   ↳ java.lang.runtime.SwitchBootstraps

Bootstrap methods for linking invokedynamic call sites that implement the selection functionality of the switch statement. The bootstraps take additional static arguments corresponding to the case labels of the switch, implicitly numbered sequentially from [0..N).

Summary

Public methods
open static CallSite!
enumSwitch(lookup: MethodHandles.Lookup!, invocationName: String!, invocationType: MethodType!, vararg labels: Any!)

Bootstrap method for linking an invokedynamic call site that implements a switch on a target of an enum type.
open static CallSite!
typeSwitch(lookup: MethodHandles.Lookup!, invocationName: String!, invocationType: MethodType!, vararg labels: Any!)

Bootstrap method for linking an invokedynamic call site that implements a switch on a target of a reference type.

Public methods

enumSwitch

Added in API level Baklava
open static fun enumSwitch(
    lookup: MethodHandles.Lookup!, 
    invocationName: String!, 
    invocationType: MethodType!, 
    vararg labels: Any!
): CallSite!

Bootstrap method for linking an invokedynamic call site that implements a switch on a target of an enum type. The static arguments are used to encode the case labels associated to the switch construct, where each label can be encoded in two ways:

  • as a String value, which represents the name of the enum constant associated with the label
  • as a Class value, which represents the enum type associated with a type test pattern

The returned CallSite's method handle will have a return type of int and accepts two parameters: the first argument will be an Enum instance (target) and the second will be int (restart).

If the target is null, then the method of the call site returns -1.

If the target is not null, then the method of the call site returns the index of the first element in the labels array starting from the restart index matching one of the following conditions:

  • the element is of type Class that is assignable from the target's class; or
  • the element is of type String and equals to the target enum constant's Enum.name().

If no element in the labels array matches the target, then the method of the call site return the length of the labels array.

The value of the restart index must be between 0 (inclusive) and the length of the labels array (inclusive), both or an IndexOutOfBoundsException is thrown.

Parameters
lookup MethodHandles.Lookup!: Represents a lookup context with the accessibility privileges of the caller. When used with invokedynamic, this is stacked automatically by the VM.
invocationName String!: unused
invocationType MethodType!: The invocation type of the CallSite with two parameters, an enum type, an int, and int as a return type.
labels Any!: case labels - String constants and Class instances, in any combination
Return
CallSite! a CallSite returning the first matching element as described above
Exceptions
java.lang.NullPointerException if any argument is null
java.lang.IllegalArgumentException if any element in the labels array is null, if the invocation type is not a method type whose first parameter type is an enum type, second parameter of type int and whose return type is int, or if labels contains an element that is not of type String or Class of the target enum type.

typeSwitch

Added in API level Baklava
open static fun typeSwitch(
    lookup: MethodHandles.Lookup!, 
    invocationName: String!, 
    invocationType: MethodType!, 
    vararg labels: Any!
): CallSite!

Bootstrap method for linking an invokedynamic call site that implements a switch on a target of a reference type. The static arguments are an array of case labels which must be non-null and of type String or Integer or Class or EnumDesc.

The type of the returned CallSite's method handle will have a return type of int. It has two parameters: the first argument will be an Object instance (target) and the second will be int (restart).

If the target is null, then the method of the call site returns -1.

If the target is not null, then the method of the call site returns the index of the first element in the labels array starting from the restart index matching one of the following conditions:

  • the element is of type Class that is assignable from the target's class; or
  • the element is of type String or Integer and equals to the target.
  • the element is of type EnumDesc, that describes a constant that is equals to the target.

If no element in the labels array matches the target, then the method of the call site return the length of the labels array.

The value of the restart index must be between 0 (inclusive) and the length of the labels array (inclusive), both or an IndexOutOfBoundsException is thrown.

Parameters
lookup MethodHandles.Lookup!: Represents a lookup context with the accessibility privileges of the caller. When used with invokedynamic, this is stacked automatically by the VM.
invocationName String!: unused
invocationType MethodType!: The invocation type of the CallSite with two parameters, a reference type, an int, and int as a return type.
labels Any!: case labels - String and Integer constants and Class and EnumDesc instances, in any combination
Return
CallSite! a CallSite returning the first matching element as described above
Exceptions
java.lang.NullPointerException if any argument is null
java.lang.IllegalArgumentException if any element in the labels array is null, if the invocation type is not not a method type of first parameter of a reference type, second parameter of type int and with int as its return type, or if labels contains an element that is not of type String, Integer, Class or EnumDesc.