SwitchBootstraps
public
class
SwitchBootstraps
extends Object
java.lang.Object | |
↳ | 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 | |
---|---|
static
CallSite
|
enumSwitch(MethodHandles.Lookup lookup, String invocationName, MethodType invocationType, Object... labels)
Bootstrap method for linking an |
static
CallSite
|
typeSwitch(MethodHandles.Lookup lookup, String invocationName, MethodType invocationType, Object... labels)
Bootstrap method for linking an |
Inherited methods | |
---|---|
Public methods
enumSwitch
public static CallSite enumSwitch (MethodHandles.Lookup lookup, String invocationName, MethodType invocationType, Object... labels)
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'sEnum.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 |
Object : case labels - String constants and Class instances,
in any combination |
Returns | |
---|---|
CallSite |
a CallSite returning the first matching element as described above |
Throws | |
---|---|
NullPointerException |
if any argument is null |
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
public static CallSite typeSwitch (MethodHandles.Lookup lookup, String invocationName, MethodType invocationType, Object... labels)
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
orInteger
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 |
Object : case labels - String and Integer constants
and Class and EnumDesc instances, in any combination |
Returns | |
---|---|
CallSite |
a CallSite returning the first matching element as described above |
Throws | |
---|---|
NullPointerException |
if any argument is null |
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 . |