/*

 * Copyright (c) 2014, 2015, 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.type;

import jdk.vm.ci.meta.Constant;

import jdk.vm.ci.meta.JavaConstant;

import jdk.vm.ci.meta.JavaKind;

/**

 * Abstract base class of all pointer types.

 */

public abstract class AbstractPointerStamp extends Stamp {

    private final boolean nonNull;

    private final boolean alwaysNull;

    protected AbstractPointerStamp(boolean nonNull, boolean alwaysNull) {

        this.nonNull = nonNull;

        this.alwaysNull = alwaysNull;

    }

    public boolean nonNull() {

        assert !this.isEmpty() || nonNull;

        return nonNull;

    }

    public boolean alwaysNull() {

        return alwaysNull;

    }

    protected abstract AbstractPointerStamp copyWith(boolean newNonNull, boolean newAlwaysNull);

    @Override

    public int hashCode() {

        final int prime = 31;

        int result = 1;

        result = prime * result + (alwaysNull ? 1231 : 1237);

        result = prime * result + (nonNull ? 1231 : 1237);

        return result;

    }

    protected Stamp defaultPointerJoin(Stamp stamp) {

        assert getClass() == stamp.getClass();

        AbstractPointerStamp other = (AbstractPointerStamp) stamp;

        boolean joinNonNull = this.nonNull || other.nonNull;

        boolean joinAlwaysNull = this.alwaysNull || other.alwaysNull;

        if (joinNonNull && joinAlwaysNull) {

            return empty();

        } else {

            return copyWith(joinNonNull, joinAlwaysNull);

        }

    }

    @Override

    public Stamp improveWith(Stamp other) {

        return join(other);

    }

    @Override

    public Stamp meet(Stamp stamp) {

        AbstractPointerStamp other = (AbstractPointerStamp) stamp;

        boolean meetNonNull = this.nonNull && other.nonNull;

        boolean meetAlwaysNull = this.alwaysNull && other.alwaysNull;

        return copyWith(meetNonNull, meetAlwaysNull);

    }

    @Override

    public Stamp unrestricted() {

        return copyWith(false, false);

    }

    public static Stamp pointerNonNull(Stamp stamp) {

        AbstractPointerStamp pointer = (AbstractPointerStamp) stamp;

        return pointer.asNonNull();

    }

    public static Stamp pointerMaybeNull(Stamp stamp) {

        AbstractPointerStamp pointer = (AbstractPointerStamp) stamp;

        return pointer.asMaybeNull();

    }

    public static Stamp pointerAlwaysNull(Stamp stamp) {

        AbstractPointerStamp pointer = (AbstractPointerStamp) stamp;

        return pointer.asAlwaysNull();

    }

    public Stamp asNonNull() {

        if (isEmpty()) {

            return this;

        }

        return copyWith(true, false);

    }

    public Stamp asMaybeNull() {

        if (isEmpty()) {

            return this;

        }

        return copyWith(false, false);

    }

    public Stamp asAlwaysNull() {

        if (isEmpty()) {

            return this;

        }

        return copyWith(false, true);

    }

    @Override

    public boolean equals(Object obj) {

        if (this == obj) {

            return true;

        }

        if (obj == null || getClass() != obj.getClass()) {

            return false;

        }

        AbstractPointerStamp other = (AbstractPointerStamp) obj;

        return this.alwaysNull == other.alwaysNull && this.nonNull == other.nonNull;

    }

    @Override

    public Constant asConstant() {

        if (alwaysNull) {

            return JavaConstant.NULL_POINTER;

        } else {

            return null;

        }

    }

    @Override

    public JavaKind getStackKind() {

        return JavaKind.Illegal;

    }

}