/*
 * Copyright (c) 2014, 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.utilities;

import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;

/**
 * Represents a {@link ValueProfile} that speculates on the exact class of a value.
 */
final class ExactClassValueProfile extends ValueProfile {

    @CompilationFinal protected Class<?> cachedClass;

    ExactClassValueProfile() {
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> T profile(T value) {
        Class<?> c = cachedClass;
        if (c != Object.class) {
            if (c != null && value != null && c == value.getClass()) {
                if (CompilerDirectives.inInterpreter()) {
                    return value;
                } else {
                    return (T) c.cast(value);
                }
            } else {
                CompilerDirectives.transferToInterpreterAndInvalidate();
                if (c == null && value != null) {
                    cachedClass = value.getClass();
                } else {
                    cachedClass = Object.class;
                }
            }
        }
        return value;
    }

    public boolean isGeneric() {
        return cachedClass == Object.class;
    }

    public boolean isUninitialized() {
        return cachedClass == null;
    }

    public Class<?> getCachedClass() {
        return cachedClass;
    }

    @Override
    public String toString() {
        return String.format("%s(%s)@%x", getClass().getSimpleName(), isUninitialized() ? "uninitialized" : (isGeneric() ? "generic" : cachedClass.getName()), hashCode());
    }
}