/*
 * Copyright (c) 2013, 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.*;
import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
import com.oracle.truffle.api.nodes.*;

/**
 * A {@link CompilationFinal} value combined with an {@link Assumption} to notify when it changes.
 * Note that you should be careful that modifications to this value do not cause deoptimization
 * loops. This could be by using a value that is monotonic.
 */
public class AssumedValue<T> {

    @CompilationFinal private T value;
    private final CyclicAssumption assumption;

    public AssumedValue(String name, T initialValue) {
        assumption = new CyclicAssumption(name);
        value = initialValue;
    }

    /**
     * Get the current value, updating it if it has been {@link #set}. The compiler may be able to
     * make this method return a constant value, but still accommodate mutation.
     */
    public T get() {
        try {
            assumption.getAssumption().check();
        } catch (InvalidAssumptionException e) {
            // No need to rewrite anything - just pick up the new value
        }

        return value;
    }

    /**
     * Set a new value, which will be picked up the next time {@link #get} is called.
     */
    public void set(T newValue) {
        value = newValue;
        assumption.invalidate();
    }

}

@@ -18,16 +18,22 @@
 c) 2013,
+ 2014,
  Oracle 
@@ -1684,16 +1684,48 @@
 e%3CT%3E %7B%0A%0A
+    private final String name;%0A%0A
     @Com
@@ -1763,28 +1763,34 @@
     
-private final Cyclic
+@CompilationFinal private 
 Assu
@@ -1837,21 +1837,8 @@
 lue(
-String name, 
 T in
@@ -1863,77 +1863,216 @@
     
-assumption = new Cyc
+this(null, initialValue);%0A    %7D%0A%0A    pub
 lic
+ 
 Assum
-ption(name);%0A        value = initialValue
+edValue(String name, T initialValue) %7B%0A        this.name = name;%0A        value = initialValue;%0A        assumption = Truffle.getRuntime().createAssumption(name)
 ;%0A  
@@ -2334,24 +2334,8 @@
 ion.
-getAssumption().
 chec
@@ -2459,16 +2459,17 @@
 ew value
+s
 %0A       
@@ -2649,35 +2649,210 @@
     
-value = newValue;%0A        a
+CompilerDirectives.transferToInterpreter();%0A%0A        value = newValue;%0A        final Assumption oldAssumption = assumption;%0A        assumption = Truffle.getRuntime().createAssumption(name);%0A        oldA
 ssum

fix AssumedValue.