/*
 * Copyright (c) 2009, 2011, 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 com.sun.cri.ci;

import java.io.*;



/**
 * Abstract base class for values manipulated by the compiler. All values have a {@linkplain CiKind kind} and are immutable.
 */
public abstract class CiValue implements Serializable {
    private static final long serialVersionUID = -6909397188697766469L;

    @SuppressWarnings("serial")
    public static CiValue IllegalValue = new CiValue(CiKind.Illegal) {
        @Override
        public String name() {
            return "<illegal>";
        }
        @Override
        public CiRegister asRegister() {
            return CiRegister.None;
        }
        @Override
        public int hashCode() {
            return -1;
        }
        @Override
        public boolean equals(Object obj) {
            return obj == this;
        }
        @Override
        public boolean equalsIgnoringKind(CiValue other) {
            return other == this;
        }
    };

    /**
     * The kind of this value.
     */
    public final CiKind kind;

    /**
     * Initializes a new value of the specified kind.
     * @param kind the kind
     */
    protected CiValue(CiKind kind) {
        this.kind = kind;
    }

    public final boolean isVariableOrRegister() {
        return this instanceof CiVariable || this instanceof CiRegisterValue;
    }

    public CiRegister asRegister() {
        throw new InternalError("Not a register: " + this);
    }

    public final boolean isIllegal() {
        return this == IllegalValue;
    }

    public final boolean isLegal() {
        return this != IllegalValue;
    }

    /**
     * Determines if this value represents a slot on a stack. These values are created
     * by the register allocator for spill slots. They are also used to model method
     * parameters passed on the stack according to a specific calling convention.
     */
    public final boolean isStackSlot() {
        return this instanceof CiStackSlot;
    }

    public final boolean isRegister() {
        return this instanceof CiRegisterValue;
    }

    public final boolean isVariable() {
        return this instanceof CiVariable;
    }

    public final boolean isAddress() {
        return this instanceof CiAddress;
    }

    public final boolean isConstant() {
        return this instanceof CiConstant;
    }

    /**
     * Gets a string name for this value without indicating its {@linkplain #kind kind}.
     */
    public abstract String name();

    @Override
    public abstract boolean equals(Object obj);

    public abstract boolean equalsIgnoringKind(CiValue other);

    @Override
    public abstract int hashCode();

    @Override
    public final String toString() {
        return name() + kindSuffix();
    }

    public final String kindSuffix() {
        if (kind == CiKind.Illegal) {
            return "";
        }
        return ":" + kind.typeChar;
    }

    public final boolean isConstant0() {
        return isConstant() && ((CiConstant) this).asInt() == 0;
    }

    /**
     * Utility for specializing how a {@linkplain CiValue LIR operand} is formatted to a string.
     * The {@linkplain Formatter#DEFAULT default formatter} returns the value of
     * {@link CiValue#toString()}.
     */
    public static class Formatter {
        public static final Formatter DEFAULT = new Formatter();

        /**
         * Formats a given operand as a string.
         *
         * @param operand the operand to format
         * @return {@code operand} as a string
         */
        public String format(CiValue operand) {
            return operand.toString();
        }
    }

}