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LambdaToMethodBridgeBuilder.java
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LambdaToMethodBridgeBuilder.java
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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package software.amazon.awssdk.enhanced.dynamodb.internal.mapper;
import static software.amazon.awssdk.utils.FunctionalUtils.invokeSafely;
import java.lang.invoke.LambdaMetafactory;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import software.amazon.awssdk.annotations.SdkInternalApi;
import software.amazon.awssdk.utils.Either;
@SdkInternalApi
public class LambdaToMethodBridgeBuilder<T> {
private static final MethodHandles.Lookup LOOKUP = MethodHandles.lookup();
private final Class<T> lambdaType;
private String lambdaMethodName;
private Class<?> postEraseLambdaReturnType;
private Class<?>[] postEraseLambdaParameters;
private Class<?> preEraseLambdaReturnType;
private Class<?>[] preEraseLambdaParameters;
private Either<Method, Constructor<?>> targetMethod;
private LambdaToMethodBridgeBuilder(Class<T> lambdaType) {
this.lambdaType = lambdaType;
}
public static <T> LambdaToMethodBridgeBuilder<T> create(Class<T> lambdaType) {
return new LambdaToMethodBridgeBuilder<>(lambdaType);
}
public LambdaToMethodBridgeBuilder<T> lambdaMethodName(String lambdaMethodName) {
this.lambdaMethodName = lambdaMethodName;
return this;
}
public LambdaToMethodBridgeBuilder<T> runtimeLambdaSignature(Class<?> returnType, Class<?>... parameters) {
this.postEraseLambdaReturnType = returnType;
this.postEraseLambdaParameters = parameters.clone();
return this;
}
public LambdaToMethodBridgeBuilder<T> compileTimeLambdaSignature(Class<?> returnType, Class<?>... parameters) {
this.preEraseLambdaReturnType = returnType;
this.preEraseLambdaParameters = parameters.clone();
return this;
}
public LambdaToMethodBridgeBuilder<T> targetMethod(Method method) {
this.targetMethod = Either.left(method);
return this;
}
public LambdaToMethodBridgeBuilder<T> targetMethod(Constructor<?> method) {
this.targetMethod = Either.right(method);
return this;
}
public T build() {
try {
MethodHandle targetMethodHandle = targetMethod.map(
m -> invokeSafely(() -> LOOKUP.unreflect(m)),
c -> invokeSafely(() -> LOOKUP.unreflectConstructor(c)));
return lambdaType.cast(
LambdaMetafactory.metafactory(LOOKUP,
lambdaMethodName,
MethodType.methodType(lambdaType),
MethodType.methodType(postEraseLambdaReturnType, postEraseLambdaParameters),
targetMethodHandle,
MethodType.methodType(preEraseLambdaReturnType, preEraseLambdaParameters))
.getTarget()
.invoke());
} catch (Throwable e) {
throw new IllegalArgumentException("Failed to generate method handle.", e);
}
}
}