/*
 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.truffle.api.impl;

import com.oracle.truffle.api.CallTarget;
import com.oracle.truffle.api.RootCallTarget;
import com.oracle.truffle.api.Truffle;
import com.oracle.truffle.api.TruffleRuntime;
import com.oracle.truffle.api.frame.Frame;
import com.oracle.truffle.api.frame.FrameInstance;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.api.nodes.RootNode;

/**
 * This is an implementation-specific class. Do not use or instantiate it. Instead, use
 * {@link TruffleRuntime#createCallTarget(RootNode)} to create a {@link RootCallTarget}.
 */
public class DefaultCallTarget implements RootCallTarget {

    private final RootNode rootNode;

    protected DefaultCallTarget(RootNode function) {
        this.rootNode = function;
        this.rootNode.adoptChildren();
        this.rootNode.applyInstrumentation();
    }

    @Override
    public String toString() {
        return rootNode.toString();
    }

    public final RootNode getRootNode() {
        return rootNode;
    }

    @Override
    public Object call(Object... args) {
        final VirtualFrame frame = new DefaultVirtualFrame(getRootNode().getFrameDescriptor(), args);
        FrameInstance oldCurrentFrame = defaultTruffleRuntime().setCurrentFrame(new FrameInstance() {

            public Frame getFrame(FrameAccess access, boolean slowPath) {
                return frame;
            }

            public boolean isVirtualFrame() {
                return false;
            }

            public Node getCallNode() {
                return null;
            }

            public CallTarget getCallTarget() {
                return DefaultCallTarget.this;
            }
        });
        try {
            return getRootNode().execute(frame);
        } finally {
            defaultTruffleRuntime().setCurrentFrame(oldCurrentFrame);
        }
    }

    private static DefaultTruffleRuntime defaultTruffleRuntime() {
        return (DefaultTruffleRuntime) Truffle.getRuntime();
    }
}