com.headius.invokebinder

Class SmartHandle

java.lang.Object

com.headius.invokebinder.SmartHandle

public class SmartHandle
extends Object

A tuple of a Signature and a java.lang.invoke.MethodHandle, providing features of both plus a number of MethodHandles.* methods in a simpler form. SmartHandle is provided as a way to couple a given MethodHandle to a Signature, allowing future adaptation of the MethodHandle to proceed using Signature's various shortcuts and conveniences. Example: // A signature that only wants the "context" and "args" arguments public static final Signature ARG_COUNT_CHECK_FOLD = Signature .returning(void.class) .appendArg("args", Object[].class); // The actual target signature for arg count checking, with min and max ints public static final Signature ARG_COUNT_CHECK_SIGNATURE = Signature .returning(int.class) .appendArg("args", Object[].class) .appendArg("min", int.class) .appendArg("max", int.class); // A SmartHandle for the arity-checking method, using the fold and signature // from above and inserting 1, 3 for min, max SmartHandle arityCheck = SmartBinder .from(ARITY_CHECK_FOLD) .append("min", 1) .append("max", 3) .cast(ARITY_CHECK_SIGNATURE) .invokeStaticQuiet(LOOKUP, ArgCountChecker.class, "checkArgumentCount"); // The variable-arity call contaings other arguments plus the Object[] args. // Here, we can just fold with our arityCheck SmartHandle, which drops args // we are not interested in, passes along the args array, and ignores the // return value. variableCall = SmartBinder .from(VARIABLE_ARITY_SIGNATURE) .foldVoid(arityCheck) .invoke(directCall);

Author:

headius

Method Summary

Methods

Modifier and Type	Method and Description
SmartHandle	apply(int index, Object arg) Apply an argument into the handle at the given index, returning a new SmartHandle.
SmartHandle	apply(String name, Object arg) Apply an argument into the handle at the given name, returning a new SmartHandle.
SmartHandle	applyLast(Object arg) Apply an argument into the handle at the end, returning a new SmartHandle.
SmartHandle	bindTo(Object obj) Bind the first argument of this SmartHandle to the given object, returning a new adapted handle.
SmartHandle	cast(Class returnType, Class... argTypes) Create a new SmartHandle that casts arguments from the given return type and argument types to the current signature's type, using the same argument names.
SmartHandle	cast(java.lang.invoke.MethodType incoming) Create a new SmartHandle that casts arguments from the given type to the current signature's type, using the same argument names.
SmartHandle	cast(Signature incoming) Create a new SmartHandle that casts arguments from the given signature to the current signature's type with the new argument names.
SmartHandle	convert(Class returnType, Class... argTypes) Create a new SmartHandle that converts arguments from the given return type and argument types to the current signature's type, using the same argument names.
SmartHandle	convert(java.lang.invoke.MethodType incoming) Create a new SmartHandle that converts arguments from the given type to the current signature's type, using the same argument names.
SmartHandle	convert(Signature incoming) Create a new SmartHandle that converts arguments from the given signature to the current signature's type with the new argument names.
SmartHandle	drop(int index, String newName, Class type) Insert an argument into the handle at the given index, returning a new SmartHandle.
SmartHandle	drop(String beforeName, String newName, Class type) Insert an argument into the handle at the given index, returning a new SmartHandle.
SmartHandle	dropLast(String newName, Class type) Insert an argument into the handle at the given index, returning a new SmartHandle.
static SmartHandle	findStaticQuiet(java.lang.invoke.MethodHandles.Lookup lookup, Class target, String name, Signature signature) Create a new SmartHandle by performing a lookup on the given target class for the given method name with the given signature.
static SmartHandle	from(Signature signature, java.lang.invoke.MethodHandle handle) Create a new SmartHandle from the given Signature and MethodHandle.
java.lang.invoke.MethodHandle	guard(java.lang.invoke.MethodHandle target, java.lang.invoke.MethodHandle fallback) Use this SmartHandle as a test to guard target and fallback handles.
SmartHandle	guard(SmartHandle target, SmartHandle fallback) Use this SmartHandle as a test to guard target and fallback handles.
java.lang.invoke.MethodHandle	handle() Get the MethodHandle of this SmartHandle.
SmartHandle	returnValue(Class type, Object value) Replace the return value with the given value, performing no other processing of the original value.
Signature	signature() Get the Signature of this SmartHandle.
String	toString() A human-readable String representation of this SamrtHandle.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

from

public static SmartHandle from(Signature signature,
               java.lang.invoke.MethodHandle handle)

Create a new SmartHandle from the given Signature and MethodHandle.

Parameters:

signature - the signature for the new smart handle

handle - the method handle for the new smart handle

Returns:

a new SmartHandle

findStaticQuiet

public static SmartHandle findStaticQuiet(java.lang.invoke.MethodHandles.Lookup lookup,
                          Class target,
                          String name,
                          Signature signature)

Create a new SmartHandle by performing a lookup on the given target class for the given method name with the given signature.

Parameters:

lookup - the MethodHandles.Lookup object to use

target - the class where the method is located

name - the name of the method

signature - the signature of the method

Returns:

a new SmartHandle based on the signature and looked-up MethodHandle

signature

public Signature signature()

Get the Signature of this SmartHandle.

Returns:

the Signature of this SmartHandle

handle

public java.lang.invoke.MethodHandle handle()

Get the MethodHandle of this SmartHandle.

Returns:

the MethodHandle of this SmartHandle

apply

public SmartHandle apply(int index,
                Object arg)

Apply an argument into the handle at the given index, returning a new SmartHandle. The new handle will use the given value for the argument at the given index, accepting one fewer argument as a result. In other words, fix that argument (partial application) into the given handle.

Parameters:

name - the name of the argument in the new SmartHandle's Signature

arg - the argument value

Returns:

a new SmartHandle that already has applied the given argument

apply

public SmartHandle apply(String name,
                Object arg)

Apply an argument into the handle at the given name, returning a new SmartHandle. The new handle will use the given value for the argument at the given index, accepting one fewer argument as a result. In other words, fix that argument (partial application) into the given handle.

Parameters:

name - the name of the argument in the new SmartHandle's Signature

arg - the argument value

Returns:

a new SmartHandle that already has applied the given argument

applyLast

public SmartHandle applyLast(Object arg)

Apply an argument into the handle at the end, returning a new SmartHandle. The new handle will use the given value for the last argument, accepting one fewer argument as a result. In other words, fix that argument (partial application) into the given handle.

Parameters:

name - the name of the argument in the new SmartHandle's Signature

arg - the argument value

Returns:

a new SmartHandle that already has applied the given argument

drop

public SmartHandle drop(String beforeName,
               String newName,
               Class type)

Insert an argument into the handle at the given index, returning a new SmartHandle.

Parameters:

name - the name of the argument in the new SmartHandle's Signature

arg - the argument value

Returns:

a new SmartHandle with the additional argument

drop

public SmartHandle drop(int index,
               String newName,
               Class type)

Insert an argument into the handle at the given index, returning a new SmartHandle.

Parameters:

name - the name of the argument in the new SmartHandle's Signature

arg - the argument value

Returns:

a new SmartHandle with the additional argument

dropLast

public SmartHandle dropLast(String newName,
                   Class type)

Insert an argument into the handle at the given index, returning a new SmartHandle.

Parameters:

name - the name of the argument in the new SmartHandle's Signature

arg - the argument value

Returns:

a new SmartHandle with the additional argument

guard

public java.lang.invoke.MethodHandle guard(java.lang.invoke.MethodHandle target,
                                  java.lang.invoke.MethodHandle fallback)

Use this SmartHandle as a test to guard target and fallback handles.

Parameters:

target - the "true" path for this handle's test

fallback - the "false" path for this handle's test

Returns:

a MethodHandle that performs the test and branch

guard

public SmartHandle guard(SmartHandle target,
                SmartHandle fallback)

Use this SmartHandle as a test to guard target and fallback handles.

Parameters:

target - the "true" path for this handle's test

fallback - the "false" path for this handle's test

Returns:

a new SmartHandle that performs the test and branch

bindTo

public SmartHandle bindTo(Object obj)

Bind the first argument of this SmartHandle to the given object, returning a new adapted handle.

Parameters:

obj - the object to which to bind this handle's first argument

Returns:

a new SmartHandle with the first argument dropped in favor of obj

convert

public SmartHandle convert(java.lang.invoke.MethodType incoming)

Create a new SmartHandle that converts arguments from the given type to the current signature's type, using the same argument names. This conversion is equivalent to MethodHandle#asType.

Parameters:

incoming - the target MethodType from which arguments will be converted

Returns:

a new SmartHandle that accepts the given argument types

convert

public SmartHandle convert(Class returnType,
                  Class... argTypes)

Create a new SmartHandle that converts arguments from the given return type and argument types to the current signature's type, using the same argument names. This conversion is equivalent to MethodHandle#asType.

Parameters:

returnType - the return type of the new handle

argTypes - the argument types of the new handle

Returns:

a new SmartHandle that accepts the given argument types

convert

public SmartHandle convert(Signature incoming)

Create a new SmartHandle that converts arguments from the given signature to the current signature's type with the new argument names. This conversion is equivalent to MethodHandle#asType.

Parameters:

incoming - the target MethodType from which arguments will be converted

Returns:

a new SmartHandle that accepts the given argument types

cast

public SmartHandle cast(java.lang.invoke.MethodType incoming)

Create a new SmartHandle that casts arguments from the given type to the current signature's type, using the same argument names. This casting is equivalent to MethodHandles#explicitCastArguments.

Parameters:

incoming - the target MethodType from which arguments will be converted

Returns:

a new SmartHandle that accepts the given argument types

cast

public SmartHandle cast(Signature incoming)

Create a new SmartHandle that casts arguments from the given signature to the current signature's type with the new argument names. This casting is equivalent to MethodHandle#asType.

Parameters:

incoming - the target MethodType from which arguments will be converted

Returns:

a new SmartHandle that accepts the given argument types

cast

public SmartHandle cast(Class returnType,
               Class... argTypes)

Create a new SmartHandle that casts arguments from the given return type and argument types to the current signature's type, using the same argument names. This casting is equivalent to MethodHandle#asType.

Parameters:

returnType - the return type of the new handle

argTypes - the argument types of the new handle

Returns:

a new SmartHandle that accepts the given argument types

returnValue

public SmartHandle returnValue(Class type,
                      Object value)

Replace the return value with the given value, performing no other processing of the original value.

Parameters:

value - the type for the new return value

value - the new value to return

toString

public String toString()

A human-readable String representation of this SamrtHandle.

Overrides:

toString in class Object

Returns:

a String representation of this handle