/*
 * Copyright (c) 2009, 2016, 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 jdk.vm.ci.code;

import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

/**
 * An immutable ordered list of registers. Only required because Java lacks immutable arrays.
 */
public final class RegisterArray implements Iterable<Register> {

    private final Register[] registers;
    private int hash;

    public RegisterArray(Register... registers) {
        this.registers = registers;
    }

    public RegisterArray(Collection<Register> registers) {
        this.registers = registers.toArray(new Register[registers.size()]);
    }

    /**
     * Gets the number of registers.
     */
    public int size() {
        return registers.length;
    }

    /**
     * Gets the register at a given index.
     *
     * @param index the index of the register to retrieve
     */
    public Register get(int index) {
        return registers[index];
    }

    public void addTo(Collection<Register> collection) {
        collection.addAll(Arrays.asList(registers));
    }

    /**
     * Gets an immutable view of the registers as a list.
     */
    public List<Register> asList() {
        return Collections.unmodifiableList(Arrays.asList(registers));
    }

    /**
     * Gets a copy of the registers as an array.
     */
    public Register[] toArray() {
        return registers.clone();
    }

    public Iterator<Register> iterator() {
        return Arrays.asList(registers).iterator();
    }

    @Override
    public int hashCode() {
        if (hash == 0 && registers.length > 0) {
            hash = Arrays.hashCode(registers);
        }
        return hash;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof RegisterArray) {
            return Arrays.equals(registers, ((RegisterArray) obj).registers);
        }
        return false;
    }

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