/*

 * Copyright (c) 2012, 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.

 *

 * 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 org.graalvm.compiler.core.common.cfg;

import java.util.ArrayList;

import java.util.List;

public abstract class Loop<T extends AbstractBlockBase<T>> {

    private final Loop<T> parent;

    private final List<Loop<T>> children;

    private final int depth;

    private final int index;

    private final T header;

    private final List<T> blocks;

    private final List<T> exits;

    protected Loop(Loop<T> parent, int index, T header) {

        this.parent = parent;

        if (parent != null) {

            this.depth = parent.getDepth() + 1;

            parent.getChildren().add(this);

        } else {

            this.depth = 1;

        }

        this.index = index;

        this.header = header;

        this.blocks = new ArrayList<>();

        this.children = new ArrayList<>();

        this.exits = new ArrayList<>();

    }

    public abstract long numBackedges();

    @Override

    public String toString() {

        return "loop " + index + " depth " + getDepth() + (parent != null ? " outer " + parent.index : "");

    }

    public Loop<T> getParent() {

        return parent;

    }

    public List<Loop<T>> getChildren() {

        return children;

    }

    public int getDepth() {

        return depth;

    }

    public int getIndex() {

        return index;

    }

    public T getHeader() {

        return header;

    }

    public List<T> getBlocks() {

        return blocks;

    }

    public List<T> getExits() {

        return exits;

    }

    public void addExit(T t) {

        exits.add(t);

    }

    /**

     * Determines if one loop is a transitive parent of another loop.

     *

     * @param childLoop The loop for which parentLoop might be a transitive parent loop.

     * @param parentLoop The loop which might be a transitive parent loop of child loop.

     * @return {@code true} if parentLoop is a (transitive) parent loop of childLoop, {@code false}

     *         otherwise

     */

    public static <T extends AbstractBlockBase<T>> boolean transitiveParentLoop(Loop<T> childLoop, Loop<T> parentLoop) {

        Loop<T> curr = childLoop;

        while (curr != null) {

            if (curr == parentLoop) {

                return true;

            }

            curr = curr.getParent();

        }

        return false;

    }

    @Override

    public int hashCode() {

        return index + depth * 31;

    }

}