/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF 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.codehaus.groovy.transform.tailrec

import org.codehaus.groovy.ast.ClassHelper
import org.codehaus.groovy.ast.ClassNode
import org.codehaus.groovy.ast.CodeVisitorSupport
import org.codehaus.groovy.ast.MethodNode
import org.codehaus.groovy.ast.Parameter
import org.codehaus.groovy.ast.expr.ClosureExpression
import org.codehaus.groovy.classgen.ReturnAdder

/**
 * Adds explicit return statements to implicit return points in a closure. This is necessary since
 * tail-recursion is detected by having the recursive call within the return statement.
 */
class ReturnAdderForClosures extends CodeVisitorSupport {

    synchronized void visitMethod(MethodNode method) {
        method.code.visit(this)
    }

    void visitClosureExpression(ClosureExpression expression) {
        //Create a dummy method with the closure's code as the method's code. Then user ReturnAdder, which only works for methods.
        MethodNode node = new MethodNode('dummy', 0, ClassHelper.OBJECT_TYPE, Parameter.EMPTY_ARRAY, ClassNode.EMPTY_ARRAY, expression.code)
        new ReturnAdder().visitMethod(node)
        super.visitClosureExpression(expression)
    }

}
