ConstantCallSite
open class ConstantCallSite : CallSite
| kotlin.Any | ||
| ↳ | java.lang.invoke.CallSite | |
| ↳ | java.lang.invoke.ConstantCallSite | |
A ConstantCallSite is a CallSite whose target is permanent, and can never be changed. An invokedynamic instruction linked to a ConstantCallSite is permanently bound to the call site's target.
Summary
| Public constructors | |
|---|---|
ConstantCallSite(target: MethodHandle!)Creates a call site with a permanent target. |
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| Protected constructors | |
|---|---|
ConstantCallSite(targetType: MethodType!, createTargetHook: MethodHandle!)Creates a call site with a permanent target, possibly bound to the call site itself. |
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| Public methods | |
|---|---|
| MethodHandle! |
Returns this call site's permanent target. |
| MethodHandle! |
Returns the target method of the call site, which behaves like a |
| Unit |
setTarget(ignore: MethodHandle!)Always throws an |
| Inherited functions | |
|---|---|
Public constructors
ConstantCallSite
ConstantCallSite(target: MethodHandle!)
Creates a call site with a permanent target.
| Parameters | |
|---|---|
target |
MethodHandle!: the target to be permanently associated with this call site |
| Exceptions | |
|---|---|
java.lang.NullPointerException |
if the proposed target is null |
Protected constructors
ConstantCallSite
protected ConstantCallSite(
targetType: MethodType!,
createTargetHook: MethodHandle!)
Creates a call site with a permanent target, possibly bound to the call site itself.
During construction of the call site, the createTargetHook is invoked to produce the actual target, as if by a call of the form (MethodHandle) createTargetHook.invoke(this).
Note that user code cannot perform such an action directly in a subclass constructor, since the target must be fixed before the ConstantCallSite constructor returns.
The hook is said to bind the call site to a target method handle, and a typical action would be someTarget.bindTo(this). However, the hook is free to take any action whatever, including ignoring the call site and returning a constant target.
The result returned by the hook must be a method handle of exactly the same type as the call site.
While the hook is being called, the new ConstantCallSite object is in a partially constructed state. In this state, a call to getTarget, or any other attempt to use the target, will result in an IllegalStateException. It is legal at all times to obtain the call site's type using the type method.
| Parameters | |
|---|---|
targetType |
MethodType!: the type of the method handle to be permanently associated with this call site |
createTargetHook |
MethodHandle!: a method handle to invoke (on the call site) to produce the call site's target |
| Exceptions | |
|---|---|
java.lang.invoke.WrongMethodTypeException |
if the hook cannot be invoked on the required arguments, or if the target returned by the hook is not of the given targetType |
java.lang.NullPointerException |
if the hook returns a null value |
java.lang.ClassCastException |
if the hook returns something other than a MethodHandle |
java.lang.Throwable |
anything else thrown by the hook function |
Public methods
dynamicInvoker
fun dynamicInvoker(): MethodHandle!
Returns this call site's permanent target. Since that target will never change, this is a correct implementation of CallSite.dynamicInvoker.
| Return | |
|---|---|
MethodHandle! |
the immutable linkage state of this call site, a constant method handle |
| Exceptions | |
|---|---|
java.lang.IllegalStateException |
if the ConstantCallSite constructor has not completed |
getTarget
fun getTarget(): MethodHandle!
Returns the target method of the call site, which behaves like a final field of the ConstantCallSite. That is, the target is always the original value passed to the constructor call which created this instance.
| Return | |
|---|---|
MethodHandle! |
the immutable linkage state of this call site, a constant method handle |
| Exceptions | |
|---|---|
java.lang.IllegalStateException |
if the ConstantCallSite constructor has not completed |
setTarget
fun setTarget(ignore: MethodHandle!): Unit
Always throws an UnsupportedOperationException. This kind of call site cannot change its target.
| Parameters | |
|---|---|
newTarget |
the new target |
ignore |
MethodHandle!: a new target proposed for the call site, which is ignored |
| Exceptions | |
|---|---|
java.lang.NullPointerException |
if the proposed new target is null |
java.lang.invoke.WrongMethodTypeException |
if the proposed new target has a method type that differs from the previous target |
java.lang.UnsupportedOperationException |
because this kind of call site cannot change its target |