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/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License 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 org.elasticsearch.painless.node;

import org.elasticsearch.painless.Location;
import org.elasticsearch.painless.phase.UserTreeVisitor;

import java.util.Collections;
import java.util.List;
import java.util.Objects;

/**
 * Lambda expression node.
 * 
 * This can currently only be the direct argument of a call (method/constructor).
 * When the argument is of a known type, it uses
 * 
 * Java's lambda translation. However, if its a def call, then we don't have
 * enough information, and have to defer this until link time. In that case a placeholder
 * and all captures are pushed onto the stack and folded into the signature of the parent call.
 * 
 * For example:
 * 

 * {@code def list = new ArrayList(); int capture = 0; list.sort((x,y) -> x - y + capture)}
 * 

 * is converted into a call (pseudocode) such as:
 * 

 * {@code sort(list, lambda$0, capture)}
 * 

 * At link time, when we know the interface type, this is decomposed with MethodHandle
 * combinators back into (pseudocode):
 * 

 * {@code sort(list, lambda$0(capture))}
 */
public class ELambda extends AExpression {

    private final List canonicalTypeNameParameters;
    private final List parameterNames;
    private final SBlock blockNode;

    public ELambda(int identifier, Location location,
            List canonicalTypeNameParameters, List parameterNames, SBlock blockNode) {

        super(identifier, location);

        this.canonicalTypeNameParameters = Collections.unmodifiableList(Objects.requireNonNull(canonicalTypeNameParameters));
        this.parameterNames = Collections.unmodifiableList(Objects.requireNonNull(parameterNames));
        this.blockNode = Objects.requireNonNull(blockNode);
    }

    public List getCanonicalTypeNameParameters() {
        return canonicalTypeNameParameters;
    }

    public List getParameterNames() {
        return parameterNames;
    }

    public SBlock getBlockNode() {
        return blockNode;
    }

    @Override
    public  void visit(UserTreeVisitor userTreeVisitor, Scope scope) {
        userTreeVisitor.visitLambda(this, scope);
    }

    @Override
    public  void visitChildren(UserTreeVisitor userTreeVisitor, Scope scope) {
        blockNode.visit(userTreeVisitor, scope);
    }
}