UpdatableValue.java

/*******************************************************************************
 *
 *	Copyright (C) 2008 Fujitsu Services Ltd.
 *
 *	Author: Nick Battle
 *
 *	This file is part of VDMJ.
 *
 *	VDMJ is free software: you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License as published by
 *	the Free Software Foundation, either version 3 of the License, or
 *	(at your option) any later version.
 *
 *	VDMJ 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 for more details.
 *
 *	You should have received a copy of the GNU General Public License
 *	along with VDMJ.  If not, see <http://www.gnu.org/licenses/>.
 *
 ******************************************************************************/

package org.overture.interpreter.values;

import java.util.Set;

import org.overture.ast.analysis.AnalysisException;
import org.overture.ast.intf.lex.ILexLocation;
import org.overture.ast.lex.Dialect;
import org.overture.ast.types.PType;
import org.overture.config.Settings;
import org.overture.interpreter.runtime.Context;
import org.overture.interpreter.runtime.ValueException;
import org.overture.interpreter.scheduler.SharedStateListner;
import org.overture.parser.config.Properties;

/**
 * A class to hold an updatable value. This is almost identical to a ReferenceValue, except that is has a set method
 * which changes the referenced value and calls a listener, and all the remaining methods here are synchronized, to
 * guarantee that the sets and gets see all changes (to the same UpdateableValue) produced by other threads.
 */

public class UpdatableValue extends ReferenceValue
{
	private static final long serialVersionUID = 1L;
	public ValueListenerList listeners;
	protected final PType restrictedTo;

	public static UpdatableValue factory(Value value,
			ValueListenerList listeners)
	{
		return factory(value, listeners, null);
	}

	public static UpdatableValue factory(Value value,
			ValueListenerList listeners, PType type)
	{
		if (Settings.dialect == Dialect.VDM_RT
				&& Properties.rt_duration_transactions)
		{
			return new TransactionValue(value, listeners, type);
		} else
		{
			return new UpdatableValue(value, listeners, type);
		}
	}

	public static UpdatableValue factory(ValueListenerList listeners)
	{
		return factory(listeners, null);
	}

	public static UpdatableValue factory(ValueListenerList listeners, PType type)
	{
		if (Settings.dialect == Dialect.VDM_RT
				&& Properties.rt_duration_transactions)
		{
			return new TransactionValue(listeners, type);
		} else
		{
			return new UpdatableValue(listeners, type);
		}
	}

	protected UpdatableValue(Value value, ValueListenerList listeners,
			PType type)
	{
		super(value);
		this.listeners = listeners;
		this.restrictedTo = type;
	}

	protected UpdatableValue(ValueListenerList listeners, PType type)
	{
		super();
		this.listeners = listeners;
		this.restrictedTo = type;
	}

	@Override
	public synchronized Value getUpdatable(ValueListenerList watch)
	{
//		if (watch != null)
//		{
//			addListeners(watch);
//		}
//
//		// We have to calculate the getUpdates to propagate the combined
//		// listeners to the rest of the structure, but we do not want to
//		// create a new UpdatableValue, having updated the listeners.
//		
//		UpdatableValue uv = (UpdatableValue)value.getUpdatable(listeners);
//		value = uv.value;
//		return this;

		// Create new object every time, because we end up with two references
		// to the same value otherwise (Overture bug #544)
		return UpdatableValue.factory(value, watch);
	}

	@Override
	public synchronized Value getConstant()
	{
		return value.getConstant();
	}

	@Override
	protected
	synchronized Value convertValueTo(PType to, Context ctxt, Set<PType> done)
			throws AnalysisException
	{
		return value.convertValueTo(to, ctxt, done).getUpdatable(listeners);
	}

	@Override
	public void set(ILexLocation location, Value newval, Context ctxt)
			throws AnalysisException
	{
		// Anything with structure added to an UpdateableValue has to be
		// updatable, otherwise you can "freeze" part of the substructure
		// such that it can't be changed. And we have to set the listeners
		// to be "our" listeners, regardless of any it had before.

		synchronized (this)
		{
			value = newval.getConstant().getUpdatable(listeners);
			value = ((UpdatableValue) value).value; // To avoid nested updatables

			if (restrictedTo != null)
			{
				value = value.convertTo(restrictedTo, ctxt);
			}
		}

		// Experimental hood added for DESTECS
		if (Settings.dialect == Dialect.VDM_RT)
		{
			SharedStateListner.variableChanged(this, location);
		}

		// The listeners are outside the sync because they have to lock
		// the object they notify, which can be holding a lock on this one.

		if (listeners != null)
		{
			listeners.changedValue(location, value, ctxt);
		}
	}

	public void addListener(ValueListener listener)
	{
		if (listeners != null)
		{
			if (!listeners.contains(listener))
			{
				listeners.add(listener);
			}
		}
		else
		{
			listeners = new ValueListenerList(listener);
		}
	}

	public void addListeners(ValueListenerList list)
	{
		if (listeners == list)	// Same list
		{
			return;
		}
		else if (listeners != null)
		{
			for (ValueListener vl: list)
			{
				if (!listeners.contains(vl))
				{
					listeners.add(vl);
				}
			}
		}
		else
		{
			listeners = new ValueListenerList(list);
		}
	}

	@Override
	public synchronized Object clone()
	{
		return new UpdatableValue((Value) value.clone(), listeners, restrictedTo);
	}

	@Override
	public synchronized boolean isType(Class<? extends Value> valueclass)
	{
		return valueclass.isInstance(value.deref());
	}

	@Override
	public synchronized Value deref()
	{
		return value.deref();
	}

	@Override
	public synchronized boolean isUndefined()
	{
		return value.isUndefined();
	}

	@Override
	public synchronized boolean isVoid()
	{
		return value.isVoid();
	}

	@Override
	public synchronized double realValue(Context ctxt) throws ValueException
	{
		return value.realValue(ctxt);
	}

	@Override
	public synchronized long intValue(Context ctxt) throws ValueException
	{
		return value.intValue(ctxt);
	}

	@Override
	public synchronized long natValue(Context ctxt) throws ValueException
	{
		return value.nat1Value(ctxt);
	}

	@Override
	public synchronized long nat1Value(Context ctxt) throws ValueException
	{
		return value.nat1Value(ctxt);
	}

	@Override
	public synchronized boolean boolValue(Context ctxt) throws ValueException
	{
		return value.boolValue(ctxt);
	}

	@Override
	public synchronized char charValue(Context ctxt) throws ValueException
	{
		return value.charValue(ctxt);
	}

	@Override
	public synchronized ValueList tupleValue(Context ctxt)
			throws ValueException
	{
		return value.tupleValue(ctxt);
	}

	@Override
	public synchronized RecordValue recordValue(Context ctxt)
			throws ValueException
	{
		return value.recordValue(ctxt);
	}

	@Override
	public synchronized ObjectValue objectValue(Context ctxt)
			throws ValueException
	{
		return value.objectValue(ctxt);
	}

	@Override
	public synchronized String quoteValue(Context ctxt) throws ValueException
	{
		return value.quoteValue(ctxt);
	}

	@Override
	public synchronized ValueList seqValue(Context ctxt) throws ValueException
	{
		return value.seqValue(ctxt);
	}

	@Override
	public synchronized ValueSet setValue(Context ctxt) throws ValueException
	{
		return value.setValue(ctxt);
	}

	@Override
	public synchronized String stringValue(Context ctxt) throws ValueException
	{
		return value.stringValue(ctxt);
	}

	@Override
	public synchronized ValueMap mapValue(Context ctxt) throws ValueException
	{
		return value.mapValue(ctxt);
	}

	@Override
	public synchronized FunctionValue functionValue(Context ctxt)
			throws ValueException
	{
		return value.functionValue(ctxt);
	}

	@Override
	public synchronized OperationValue operationValue(Context ctxt)
			throws ValueException
	{
		return value.operationValue(ctxt);
	}

	@Override
	public synchronized boolean equals(Object other)
	{
		if (other instanceof Value)
		{
			Value val = ((Value) other).deref();

			if (val instanceof ReferenceValue)
			{
				ReferenceValue rvo = (ReferenceValue) val;
				return value.equals(rvo.value);
			} else
			{
				return value.equals(other);
			}
		}

		return false;
	}

	@Override
	public synchronized String kind()
	{
		return value.kind();
	}

	@Override
	public synchronized int hashCode()
	{
		return value.hashCode();
	}

	@Override
	public synchronized String toString()
	{
		return value.toString();
	}
}