modules/fdbworkers/src/flex/tools/debugger/cli/ExpressionContext.java - flex-sdk - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package flex.tools.debugger.cli;

 import java.util.StringTokenizer;
 import java.util.Vector;

 import flash.tools.debugger.Isolate;
 import flash.tools.debugger.PlayerDebugException;
 import flash.tools.debugger.Session;
 import flash.tools.debugger.SessionManager;
 import flash.tools.debugger.Value;
 import flash.tools.debugger.ValueAttribute;
 import flash.tools.debugger.Variable;
 import flash.tools.debugger.VariableType;
 import flash.tools.debugger.concrete.DValue;
 import flash.tools.debugger.events.ExceptionFault;
 import flash.tools.debugger.events.FaultEvent;
 import flash.tools.debugger.expression.Context;
 import flash.tools.debugger.expression.ExpressionEvaluatorException;
 import flash.tools.debugger.expression.NoSuchVariableException;
 import flash.tools.debugger.expression.PlayerFaultException;

 public class ExpressionContext implements Context
 {
 	ExpressionCache		m_cache;
 	Object				m_current;
 	boolean				m_createIfMissing;  // set if we need to create a variable if it doesn't exist
 	Vector<String>		m_namedPath;
 	boolean				m_nameLocked;
 	String				m_newline = System.getProperty("line.separator"); //$NON-NLS-1$
 	int m_isolateId;

 	// used when evaluating an expression
 	public ExpressionContext(ExpressionCache cache)
 	{
 		m_cache = cache;
 		m_current = null;
 		m_createIfMissing = false;
 		m_namedPath = new Vector<String>();
 		m_nameLocked = false;
 		m_isolateId = Isolate.DEFAULT_ID;
 	}

 	public void setIsolateId(int id) {
 		m_isolateId = id;
 	}

 	void		setContext(Object o)	{ m_current = o; }

 	void		pushName(String name)	{ if (m_nameLocked || name.length() < 1) return; m_namedPath.add(name);  }
 	boolean		setName(String name)	{ if (m_nameLocked) return true; m_namedPath.clear(); pushName(name); return true; }
 	void		lockName()				{ m_nameLocked = true; }

 	public String getName()
 	{
 		int size = m_namedPath.size();
 		StringBuilder sb = new StringBuilder();
 		for(int i=0; i<size; i++)
 		{
 			String s = m_namedPath.get(i);
 			if (i > 0)
 				sb.append('.');
 			sb.append(s);
 		}
 		return ( sb.toString() );
 	}

 	String getCurrentPackageName()
 	{
 		String s = null;
 		try
 		{
 			Integer o = (Integer)m_cache.get(DebugCLI.LIST_MODULE);
 			s = m_cache.getPackageName(o.intValue());
 		}
 		catch(NullPointerException npe)
 		{
 		}
 		catch(ClassCastException cce)
 		{
 		}
 		return s;
 	}

 	//
 	//
 	// Start of Context API implementation
 	//
 	//
 	public void createPseudoVariables(boolean oui) { m_createIfMissing = oui; }

 	// create a new context object by combining the current one and o
 	public Context createContext(Object o)
 	{
 		ExpressionContext c = new ExpressionContext(m_cache);
 		c.setContext(o);
 		c.createPseudoVariables(m_createIfMissing);
 		c.m_namedPath.addAll(m_namedPath);
 		c.setIsolateId(m_isolateId);
 		return c;
 	}

 	// assign the object o, the value v
 	public void assign(Object o, Value v) throws NoSuchVariableException, PlayerFaultException
 	{
 		try
 		{
 			// first see if it is an internal property (avoids player calls)
 			InternalProperty prop = resolveToInternalProperty(o);

 			// we expect that o is a variable that can be resolved or is a specially marked internal variable
 			if (prop != null)
 			{
 				assignInternal(prop, v);
 			}
 			else
 			{
 				boolean wasCreateIfMissing = m_createIfMissing;
 				createPseudoVariables(true);
 				Variable var = null;
 				try {
 					var = resolveToVariable(o);
 				} finally {
 					createPseudoVariables(wasCreateIfMissing);
 				}

 				if (var == null)
 					throw new NoSuchVariableException((var == null) ? m_current : var.getName());

 				// set the value, for the case of a variable that does not exist it will not have a type
 				// so we try to glean one from v.
 				FaultEvent faultEvent = var.setValue(getSession(), v.getType(), v.getValueAsString());
 				if (faultEvent != null)
 					throw new PlayerFaultException(faultEvent);
 			}
 		}
 		catch(PlayerDebugException pde)
 		{
 			throw new ExpressionEvaluatorException(pde);
 		}
 	}

 	/**
 	 * The Context interface which goes out and gets values from the session
 	 * Expressions use this interface as a means of evaluation.
 	 *
 	 * We also use this to create a reference to internal variables.
 	 */
 	public Object lookup(Object o) throws NoSuchVariableException, PlayerFaultException
 	{
 		Object result = null;
 		try
 		{
 			// first see if it is an internal property (avoids player calls)
 			if ( (result = resolveToInternalProperty(o)) != null)
 				;

 			// attempt to resolve to a player variable
 			else if ( (result = resolveToVariable(o)) != null)
 				;

 			// or value
 			else if ( (result = resolveToValue(o)) != null)
 				;

 			else
 				throw new NoSuchVariableException(o);

 			// take on the path to the variable; so 'what' command prints something nice
 			if ((result != null) && result instanceof VariableFacade)
 			{
 				((VariableFacade)result).setPath(getName());
 			}

 			// if the attempt to get the variable's value threw an exception inside the
 			// player (most likely because the variable is actually a getter, and the
 			// getter threw something), then throw something here
 			Value resultValue = null;

 			if (result instanceof Variable)
 			{
 				if (result instanceof VariableFacade && ((VariableFacade)result).getVariable() == null)
 					resultValue = null;
 				else
 					resultValue = ((Variable)result).getValue();
 			}
 			else if (result instanceof Value)
 			{
 				resultValue = (Value) result;
 			}

 			if (resultValue != null)
 			{
 				if (resultValue.isAttributeSet(ValueAttribute.IS_EXCEPTION))
 				{
 					String value = resultValue.getValueAsString();
 					throw new PlayerFaultException(new ExceptionFault(value, false, resultValue, resultValue.getIsolateId()));
 				}
 			}
 		}
 		catch(PlayerDebugException pde)
 		{
 			result = Value.UNDEFINED;
 		}
 		return result;
 	}

 	/* returns a string consisting of formatted member names and values */
 	public Object lookupMembers(Object o) throws NoSuchVariableException
 	{
 		Variable var = null;
 		Value val = null;
   		Variable[] mems = null;
 		try
 		{
 			var = resolveToVariable(o);
 			if (var != null)
 				val = var.getValue();
 			else
 				val = resolveToValue(o);
 			mems = val.getMembers(getSession());
 		}
 		catch(NullPointerException npe)
 		{
 			throw new NoSuchVariableException(o);
 		}
 		catch(PlayerDebugException pde)
 		{
 			throw new NoSuchVariableException(o); // not quite right...
 		}

   		StringBuilder sb = new StringBuilder();

   		if (var != null)
   			ExpressionCache.appendVariable(sb, var, m_isolateId);
   		else
   			ExpressionCache.appendVariableValue(sb, val, m_isolateId);

 		boolean attrs = m_cache.propertyEnabled(DebugCLI.DISPLAY_ATTRIBUTES);
 		if (attrs && var != null)
 			ExpressionCache.appendVariableAttributes(sb, var);

 		// [mmorearty] experimenting with hierarchical display of members
 		String[] classHierarchy = val.getClassHierarchy(false);
 		if (classHierarchy != null && getSession().getPreference(SessionManager.PREF_HIERARCHICAL_VARIABLES) != 0)
 		{
 			for (int c=0; c<classHierarchy.length; ++c)
 			{
 				String classname = classHierarchy[c];
 				sb.append(m_newline + "(Members of " + classname + ")"); //$NON-NLS-1$ //$NON-NLS-2$
 				for (int i=0; i<mems.length; ++i)
 				{
 					if (classname.equals(mems[i].getDefiningClass()))
 					{
 			  			sb.append(m_newline + " "); //$NON-NLS-1$
 			  			ExpressionCache.appendVariable(sb, mems[i], m_isolateId);
 						if (attrs)
 							ExpressionCache.appendVariableAttributes(sb, mems[i]);
 					}
 				}
 			}
 		}
 		else
 		{
 	  		for(int i=0; i<mems.length; i++)
 	  		{
 	  			sb.append(m_newline + " "); //$NON-NLS-1$
 	  			ExpressionCache.appendVariable(sb, mems[i], m_isolateId);
 				if (attrs)
 					ExpressionCache.appendVariableAttributes(sb, mems[i]);
 	  		}
 		}

   		return sb.toString();
   	}

 	//
 	//
 	// End of Context API implementation
 	//
 	//

 	// used to assign a value to an internal variable
 	private void assignInternal(InternalProperty var, Value v) throws NoSuchVariableException, NumberFormatException, PlayerDebugException
 	{
 		// otherwise set it
 		if (v.getType() != VariableType.NUMBER)
 			throw new NumberFormatException(v.getValueAsString());
 		long l = Long.parseLong(v.getValueAsString());
 		m_cache.put(var.getName(), (int)l);
 	}

 	InternalProperty resolveToInternalProperty(Object o)
 	{
 		if (o instanceof String && ((String)o).charAt(0) == '$')
 		{
 			String key = (String)o;
 			Object value = null;

 			try { value = m_cache.get(key); } catch(Exception e) {}
 			return new InternalProperty(key, value);
 		}

 		return null;
 	}

 	/**
 	 * Resolve the object into a variable by various means and
 	 * using the current context.
 	 * @return variable, or <code>null</code>
 	 */
 	Variable resolveToVariable(Object o) throws PlayerDebugException
 	{
 		Variable v = null;

 		// if o is a variable already, then we're done!
 		if (o instanceof Variable)
 			return (Variable)o;

 		/**
 		 * Resolve the name to something
 		 */
 		{
 			// not an id so try as name
 			String name = o.toString();
 			long id = nameAsId(name);

 			/**
 			 * if #N was used just pick up the variable, otherwise
 			 * we need to use the current context to resolve
 			 * the name to a member
 			 */
 			if (id != Value.UNKNOWN_ID)
 			{
 				// TODO what here?
 			}
 			else
 			{
 				// try to resolve as a member of current context (will set context if null)
 				id = determineContext(name);
 				v = locateForNamed(id, name, true);
 				if (v != null)
 					v = new VariableFacade(v, id, m_isolateId);
 				else if (v == null && m_createIfMissing && name.charAt(0) != '$')
 					v = new VariableFacade(id, name, m_isolateId);
 			}
 		}

 		/* return the variable */
 		return v;
 	}

 	/*
 	 * Resolve the object into a variable by various means and
 	 * using the current context.
 	 */
 	Value resolveToValue(Object o) throws PlayerDebugException
 	{
 		Value v = null;

 		// if o is a variable or a value already, then we're done!
 		if (o instanceof Value)
 			return (Value)o;
 		else if (o instanceof Variable)
 			return ((Variable)o).getValue();
 		else if (o instanceof InternalProperty)
 			return DValue.forPrimitive(((InternalProperty)o).m_value, m_isolateId);

 		/**
 		 * Resolve the name to something
 		 */
 		if (m_current == null)
 		{
 			// not an id so try as name
 			String name = o.toString();
 			long id = nameAsId(name);

 			/**
 			 * if #N was used just pick up the variable, otherwise
 			 * we need to use the current context to resolve
 			 * the name to a member
 			 */
 			if (id != Value.UNKNOWN_ID)
 			{
 				v = getSession().getWorkerSession(m_isolateId).getValue((int)id);
 			}
 			else if (name.equals("undefined")) //$NON-NLS-1$
 			{
 				v = DValue.forPrimitive(Value.UNDEFINED, m_isolateId);
 			}
 			else
 			{
 				// Ask the player to find something, anything, on the scope chain
 				// with this name.  We'll end up here, for example, when resolving
 				// things like MyClass, String, Number, etc.
 				v = getSession().getWorkerSession(m_isolateId).getGlobal(name);
 			}
 		}

 		/* return the value */
 		return v;
 	}

 	// special code for #N support. I.e. naming a variable via an ID
 	long nameAsId(String name)
 	{
 		long id = Value.UNKNOWN_ID;
 		try
 		{
 			if (name.charAt(0) == '#')
 				id = Long.parseLong(name.substring(1));
 		}
 		catch(Exception e)
 		{
 			id = Value.UNKNOWN_ID;
 		}
 		return id;
 	}

 	/**
 	 * Using the given id as a parent find the member named
 	 * name.
 	 * @throws NoSuchVariableException if id is UNKNOWN_ID
 	 */
 	Variable memberNamed(long id, String name) throws NoSuchVariableException, PlayerDebugException
 	{
 		Variable v = null;
 		Value parent = getSession().getWorkerSession(m_isolateId).getValue(id);

 		if (parent == null)
 			throw new NoSuchVariableException(name);

 		/* got a variable now return the member if any */
 		v = parent.getMemberNamed(getSession(), name);

 		return v;
 	}

 	/**
 	 * All the really good stuff about finding where name exists goes here!
 	 *
 	 * If name is not null, then it implies that we use the existing
 	 * m_current to find a member of m_current.  If m_current is null
 	 * Then we need to probe variable context points attempting to locate
 	 * name.  When we find a match we set the m_current to this context
 	 *
 	 * If name is null then we simply return the current context.
 	 */
 	long determineContext(String name) throws PlayerDebugException
 	{
 		long id = Value.UNKNOWN_ID;

 		// have we already resolved our context...
 		if (m_current != null)
 		{
 			id = toValue().getId();
 		}

 		// nothing to go on, so we're done
 		else if (name == null)
 			;

 		// use the name and try and resolve where we are...
 		else
 		{
 			// Each stack frame has a root variable under (BASE_ID-depth)
 			// where depth is the depth of the stack.
 			// So we query for our current stack depth and use that
 			// as the context for our base computation
 			long baseId = Value.BASE_ID;
 			int depth = ((Integer)m_cache.get(DebugCLI.DISPLAY_FRAME_NUMBER)).intValue();
 			baseId -= depth;

 			// obtain data about our current state
 			Variable contextVar = null;
 			Value contextVal = null;
 			Value val = null;

 			// look for 'name' starting from local scope
 			if ( (val = locateParentForNamed(baseId, name, false)) != null)
 				;

 			// get the this pointer, then look for 'name' starting from that point
 			else if ( ( (contextVar = locateForNamed(baseId, "this", false)) != null ) &&  //$NON-NLS-1$
 					  ( setName("this") && (val = locateParentForNamed(contextVar.getValue().getId(), name, true)) != null ) ) //$NON-NLS-1$
 				;

 			// now try to see if 'name' exists off of _root
 			else if ( setName("_root") && (val = locateParentForNamed(Value.ROOT_ID, name, true)) != null ) //$NON-NLS-1$
 				;

 			// now try to see if 'name' exists off of _global
 			else if ( setName("_global") && (val = locateParentForNamed(Value.GLOBAL_ID, name, true)) != null ) //$NON-NLS-1$
 				;

 			// now try off of class level, if such a thing can be found
 			else if ( ( (contextVal = locate(Value.GLOBAL_ID, getCurrentPackageName(), false)) != null ) &&
 					  ( setName("_global."+getCurrentPackageName()) && (val = locateParentForNamed(contextVal.getId(), name, true)) != null ) ) //$NON-NLS-1$
 				;

 			// if we found it then stake this as our context!
 			if (val != null)
 			{
 				id = val.getId();
 				pushName(name);
 				lockName();
 			}
 		}

 		return id;
 	}

 	/**
 	 * Performs a search for a member with the given name using the
 	 * given id as the parent variable.
 	 *
 	 * If a match is found then, we return the parent variable of
 	 * the member that matched.  The proto chain is optionally traversed.
 	 *
 	 * No exceptions are thrown
 	 */
 	Value locateParentForNamed(long id, String name, boolean traverseProto) throws PlayerDebugException
 	{
 		StringBuilder sb = new StringBuilder();

 		Variable var = null;
 		Value val = null;
 		try
 		{
 			var = memberNamed(id, name);

 			// see if we need to traverse the proto chain
 			while (var == null && traverseProto)
 			{
 				// first attempt to get __proto__, then resolve name
 				Variable proto = memberNamed(id, "__proto__"); //$NON-NLS-1$
  				sb.append("__proto__"); //$NON-NLS-1$
 				if (proto == null)
 					traverseProto = false;
 				else
 				{
 					id = proto.getValue().getId();
 					var = memberNamed(id, name);
 					if (var == null)
 						sb.append('.');
 				}
 			}
 		}
 		catch(NoSuchVariableException nsv)
 		{
 			// don't worry about this one, it means variable with id couldn't be found
 		}
 		catch(NullPointerException npe)
 		{
 			// probably no session
 		}

 		// what we really want is the parent not the child variable
 		if (var != null)
 		{
 			pushName(sb.toString());
 			val = getSession().getWorkerSession(m_isolateId).getValue(id);
 		}

 		return val;
 	}

 	// variant of locateParentForNamed, whereby we return the child variable
 	Variable locateForNamed(long id, String name, boolean traverseProto) throws PlayerDebugException
 	{
 		Variable var = null;
 		Value v = locateParentForNamed(id, name, traverseProto);
 		if (v != null)
 		{
 			try
 			{
 				var = memberNamed(v.getId(), name);
 			}
 			catch(NoSuchVariableException nse)
 			{
 				v = null;
 			}
 		}

 		return var;
 	}

 	/**
 	 * Locates the member via a dotted name starting at the given id.
 	 * It will traverse any and all proto chains if necc. to find the name.
 	 */
 	Value locate(long startingId, String dottedName, boolean traverseProto) throws PlayerDebugException
 	{
 		if (dottedName == null)
 			return null;

 		// first rip apart the dottedName
 		StringTokenizer names = new StringTokenizer(dottedName, "."); //$NON-NLS-1$
 		Value val = getSession().getWorkerSession(m_isolateId).getValue(startingId);

 		while(names.hasMoreTokens() && val != null)
 			val = locateForNamed(val.getId(), names.nextToken(), traverseProto).getValue();

 		return val;
 	}

 	/*
 	 * @see flash.tools.debugger.expression.Context#toValue(java.lang.Object)
 	 */
 	public Value toValue(Object o)
 	{
 		// if o is a variable or a value already, then we're done!
 		if (o instanceof Value)
 			return (Value)o;
 		else if (o instanceof Variable)
 			return ((Variable)o).getValue();
 		else if (o instanceof InternalProperty)
 			return DValue.forPrimitive(((InternalProperty)o).m_value, m_isolateId);
 		else
 			return DValue.forPrimitive(o, m_isolateId);
 	}

 	public Value toValue()
 	{
 		return toValue(m_current);
 	}

 	public Session getSession()
 	{
 		return m_cache.getSession();
 	}

 	@Override
 	public int getIsolateId() {
 		return m_isolateId;
 	}
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package flex.tools.debugger.cli;

	import java.util.StringTokenizer;
	import java.util.Vector;

	import flash.tools.debugger.Isolate;
	import flash.tools.debugger.PlayerDebugException;
	import flash.tools.debugger.Session;
	import flash.tools.debugger.SessionManager;
	import flash.tools.debugger.Value;
	import flash.tools.debugger.ValueAttribute;
	import flash.tools.debugger.Variable;
	import flash.tools.debugger.VariableType;
	import flash.tools.debugger.concrete.DValue;
	import flash.tools.debugger.events.ExceptionFault;
	import flash.tools.debugger.events.FaultEvent;
	import flash.tools.debugger.expression.Context;
	import flash.tools.debugger.expression.ExpressionEvaluatorException;
	import flash.tools.debugger.expression.NoSuchVariableException;
	import flash.tools.debugger.expression.PlayerFaultException;

	public class ExpressionContext implements Context
	{
	ExpressionCache m_cache;
	Object m_current;
	boolean m_createIfMissing; // set if we need to create a variable if it doesn't exist
	Vector<String> m_namedPath;
	boolean m_nameLocked;
	String m_newline = System.getProperty("line.separator"); //$NON-NLS-1$
	int m_isolateId;

	// used when evaluating an expression
	public ExpressionContext(ExpressionCache cache)
	{
	m_cache = cache;
	m_current = null;
	m_createIfMissing = false;
	m_namedPath = new Vector<String>();
	m_nameLocked = false;
	m_isolateId = Isolate.DEFAULT_ID;
	}

	public void setIsolateId(int id) {
	m_isolateId = id;
	}

	void setContext(Object o) { m_current = o; }

	void pushName(String name) { if (m_nameLocked \|\| name.length() < 1) return; m_namedPath.add(name); }
	boolean setName(String name) { if (m_nameLocked) return true; m_namedPath.clear(); pushName(name); return true; }
	void lockName() { m_nameLocked = true; }

	public String getName()
	{
	int size = m_namedPath.size();
	StringBuilder sb = new StringBuilder();
	for(int i=0; i<size; i++)
	{
	String s = m_namedPath.get(i);
	if (i > 0)
	sb.append('.');
	sb.append(s);
	}
	return ( sb.toString() );
	}

	String getCurrentPackageName()
	{
	String s = null;
	try
	{
	Integer o = (Integer)m_cache.get(DebugCLI.LIST_MODULE);
	s = m_cache.getPackageName(o.intValue());
	}
	catch(NullPointerException npe)
	{
	}
	catch(ClassCastException cce)
	{
	}
	return s;
	}

	//
	//
	// Start of Context API implementation
	//
	//
	public void createPseudoVariables(boolean oui) { m_createIfMissing = oui; }

	// create a new context object by combining the current one and o
	public Context createContext(Object o)
	{
	ExpressionContext c = new ExpressionContext(m_cache);
	c.setContext(o);
	c.createPseudoVariables(m_createIfMissing);
	c.m_namedPath.addAll(m_namedPath);
	c.setIsolateId(m_isolateId);
	return c;
	}

	// assign the object o, the value v
	public void assign(Object o, Value v) throws NoSuchVariableException, PlayerFaultException
	{
	try
	{
	// first see if it is an internal property (avoids player calls)
	InternalProperty prop = resolveToInternalProperty(o);

	// we expect that o is a variable that can be resolved or is a specially marked internal variable
	if (prop != null)
	{
	assignInternal(prop, v);
	}
	else
	{
	boolean wasCreateIfMissing = m_createIfMissing;
	createPseudoVariables(true);
	Variable var = null;
	try {
	var = resolveToVariable(o);
	} finally {
	createPseudoVariables(wasCreateIfMissing);
	}

	if (var == null)
	throw new NoSuchVariableException((var == null) ? m_current : var.getName());

	// set the value, for the case of a variable that does not exist it will not have a type
	// so we try to glean one from v.
	FaultEvent faultEvent = var.setValue(getSession(), v.getType(), v.getValueAsString());
	if (faultEvent != null)
	throw new PlayerFaultException(faultEvent);
	}
	}
	catch(PlayerDebugException pde)
	{
	throw new ExpressionEvaluatorException(pde);
	}
	}

	/**
	* The Context interface which goes out and gets values from the session
	* Expressions use this interface as a means of evaluation.
	*
	* We also use this to create a reference to internal variables.
	*/
	public Object lookup(Object o) throws NoSuchVariableException, PlayerFaultException
	{
	Object result = null;
	try
	{
	// first see if it is an internal property (avoids player calls)
	if ( (result = resolveToInternalProperty(o)) != null)
	;

	// attempt to resolve to a player variable
	else if ( (result = resolveToVariable(o)) != null)
	;

	// or value
	else if ( (result = resolveToValue(o)) != null)
	;

	else
	throw new NoSuchVariableException(o);

	// take on the path to the variable; so 'what' command prints something nice
	if ((result != null) && result instanceof VariableFacade)
	{
	((VariableFacade)result).setPath(getName());
	}

	// if the attempt to get the variable's value threw an exception inside the
	// player (most likely because the variable is actually a getter, and the
	// getter threw something), then throw something here
	Value resultValue = null;

	if (result instanceof Variable)
	{
	if (result instanceof VariableFacade && ((VariableFacade)result).getVariable() == null)
	resultValue = null;
	else
	resultValue = ((Variable)result).getValue();
	}
	else if (result instanceof Value)
	{
	resultValue = (Value) result;
	}

	if (resultValue != null)
	{
	if (resultValue.isAttributeSet(ValueAttribute.IS_EXCEPTION))
	{
	String value = resultValue.getValueAsString();
	throw new PlayerFaultException(new ExceptionFault(value, false, resultValue, resultValue.getIsolateId()));
	}
	}
	}
	catch(PlayerDebugException pde)
	{
	result = Value.UNDEFINED;
	}
	return result;
	}

	/* returns a string consisting of formatted member names and values */
	public Object lookupMembers(Object o) throws NoSuchVariableException
	{
	Variable var = null;
	Value val = null;
	Variable[] mems = null;
	try
	{
	var = resolveToVariable(o);
	if (var != null)
	val = var.getValue();
	else
	val = resolveToValue(o);
	mems = val.getMembers(getSession());
	}
	catch(NullPointerException npe)
	{
	throw new NoSuchVariableException(o);
	}
	catch(PlayerDebugException pde)
	{
	throw new NoSuchVariableException(o); // not quite right...
	}

	StringBuilder sb = new StringBuilder();

	if (var != null)
	ExpressionCache.appendVariable(sb, var, m_isolateId);
	else
	ExpressionCache.appendVariableValue(sb, val, m_isolateId);

	boolean attrs = m_cache.propertyEnabled(DebugCLI.DISPLAY_ATTRIBUTES);
	if (attrs && var != null)
	ExpressionCache.appendVariableAttributes(sb, var);

	// [mmorearty] experimenting with hierarchical display of members
	String[] classHierarchy = val.getClassHierarchy(false);
	if (classHierarchy != null && getSession().getPreference(SessionManager.PREF_HIERARCHICAL_VARIABLES) != 0)
	{
	for (int c=0; c<classHierarchy.length; ++c)
	{
	String classname = classHierarchy[c];
	sb.append(m_newline + "(Members of " + classname + ")"); //$NON-NLS-1$ //$NON-NLS-2$
	for (int i=0; i<mems.length; ++i)
	{
	if (classname.equals(mems[i].getDefiningClass()))
	{
	sb.append(m_newline + " "); //$NON-NLS-1$
	ExpressionCache.appendVariable(sb, mems[i], m_isolateId);
	if (attrs)
	ExpressionCache.appendVariableAttributes(sb, mems[i]);
	}
	}
	}
	}
	else
	{
	for(int i=0; i<mems.length; i++)
	{
	sb.append(m_newline + " "); //$NON-NLS-1$
	ExpressionCache.appendVariable(sb, mems[i], m_isolateId);
	if (attrs)
	ExpressionCache.appendVariableAttributes(sb, mems[i]);
	}
	}

	return sb.toString();
	}

	//
	//
	// End of Context API implementation
	//
	//

	// used to assign a value to an internal variable
	private void assignInternal(InternalProperty var, Value v) throws NoSuchVariableException, NumberFormatException, PlayerDebugException
	{
	// otherwise set it
	if (v.getType() != VariableType.NUMBER)
	throw new NumberFormatException(v.getValueAsString());
	long l = Long.parseLong(v.getValueAsString());
	m_cache.put(var.getName(), (int)l);
	}

	InternalProperty resolveToInternalProperty(Object o)
	{
	if (o instanceof String && ((String)o).charAt(0) == '$')
	{
	String key = (String)o;
	Object value = null;

	try { value = m_cache.get(key); } catch(Exception e) {}
	return new InternalProperty(key, value);
	}

	return null;
	}

	/**
	* Resolve the object into a variable by various means and
	* using the current context.
	* @return variable, or <code>null</code>
	*/
	Variable resolveToVariable(Object o) throws PlayerDebugException
	{
	Variable v = null;

	// if o is a variable already, then we're done!
	if (o instanceof Variable)
	return (Variable)o;

	/**
	* Resolve the name to something
	*/
	{
	// not an id so try as name
	String name = o.toString();
	long id = nameAsId(name);

	/**
	* if #N was used just pick up the variable, otherwise
	* we need to use the current context to resolve
	* the name to a member
	*/
	if (id != Value.UNKNOWN_ID)
	{
	// TODO what here?
	}
	else
	{
	// try to resolve as a member of current context (will set context if null)
	id = determineContext(name);
	v = locateForNamed(id, name, true);
	if (v != null)
	v = new VariableFacade(v, id, m_isolateId);
	else if (v == null && m_createIfMissing && name.charAt(0) != '$')
	v = new VariableFacade(id, name, m_isolateId);
	}
	}

	/* return the variable */
	return v;
	}

	/*
	* Resolve the object into a variable by various means and
	* using the current context.
	*/
	Value resolveToValue(Object o) throws PlayerDebugException
	{
	Value v = null;

	// if o is a variable or a value already, then we're done!
	if (o instanceof Value)
	return (Value)o;
	else if (o instanceof Variable)
	return ((Variable)o).getValue();
	else if (o instanceof InternalProperty)
	return DValue.forPrimitive(((InternalProperty)o).m_value, m_isolateId);

	/**
	* Resolve the name to something
	*/
	if (m_current == null)
	{
	// not an id so try as name
	String name = o.toString();
	long id = nameAsId(name);

	/**
	* if #N was used just pick up the variable, otherwise
	* we need to use the current context to resolve
	* the name to a member
	*/
	if (id != Value.UNKNOWN_ID)
	{
	v = getSession().getWorkerSession(m_isolateId).getValue((int)id);
	}
	else if (name.equals("undefined")) //$NON-NLS-1$
	{
	v = DValue.forPrimitive(Value.UNDEFINED, m_isolateId);
	}
	else
	{
	// Ask the player to find something, anything, on the scope chain
	// with this name. We'll end up here, for example, when resolving
	// things like MyClass, String, Number, etc.
	v = getSession().getWorkerSession(m_isolateId).getGlobal(name);
	}
	}

	/* return the value */
	return v;
	}

	// special code for #N support. I.e. naming a variable via an ID
	long nameAsId(String name)
	{
	long id = Value.UNKNOWN_ID;
	try
	{
	if (name.charAt(0) == '#')
	id = Long.parseLong(name.substring(1));
	}
	catch(Exception e)
	{
	id = Value.UNKNOWN_ID;
	}
	return id;
	}

	/**
	* Using the given id as a parent find the member named
	* name.
	* @throws NoSuchVariableException if id is UNKNOWN_ID
	*/
	Variable memberNamed(long id, String name) throws NoSuchVariableException, PlayerDebugException
	{
	Variable v = null;
	Value parent = getSession().getWorkerSession(m_isolateId).getValue(id);

	if (parent == null)
	throw new NoSuchVariableException(name);

	/* got a variable now return the member if any */
	v = parent.getMemberNamed(getSession(), name);

	return v;
	}

	/**
	* All the really good stuff about finding where name exists goes here!
	*
	* If name is not null, then it implies that we use the existing
	* m_current to find a member of m_current. If m_current is null
	* Then we need to probe variable context points attempting to locate
	* name. When we find a match we set the m_current to this context
	*
	* If name is null then we simply return the current context.
	*/
	long determineContext(String name) throws PlayerDebugException
	{
	long id = Value.UNKNOWN_ID;

	// have we already resolved our context...
	if (m_current != null)
	{
	id = toValue().getId();
	}

	// nothing to go on, so we're done
	else if (name == null)
	;

	// use the name and try and resolve where we are...
	else
	{
	// Each stack frame has a root variable under (BASE_ID-depth)
	// where depth is the depth of the stack.
	// So we query for our current stack depth and use that
	// as the context for our base computation
	long baseId = Value.BASE_ID;
	int depth = ((Integer)m_cache.get(DebugCLI.DISPLAY_FRAME_NUMBER)).intValue();
	baseId -= depth;

	// obtain data about our current state
	Variable contextVar = null;
	Value contextVal = null;
	Value val = null;

	// look for 'name' starting from local scope
	if ( (val = locateParentForNamed(baseId, name, false)) != null)
	;

	// get the this pointer, then look for 'name' starting from that point
	else if ( ( (contextVar = locateForNamed(baseId, "this", false)) != null ) && //$NON-NLS-1$
	( setName("this") && (val = locateParentForNamed(contextVar.getValue().getId(), name, true)) != null ) ) //$NON-NLS-1$
	;

	// now try to see if 'name' exists off of _root
	else if ( setName("_root") && (val = locateParentForNamed(Value.ROOT_ID, name, true)) != null ) //$NON-NLS-1$
	;

	// now try to see if 'name' exists off of _global
	else if ( setName("_global") && (val = locateParentForNamed(Value.GLOBAL_ID, name, true)) != null ) //$NON-NLS-1$
	;

	// now try off of class level, if such a thing can be found
	else if ( ( (contextVal = locate(Value.GLOBAL_ID, getCurrentPackageName(), false)) != null ) &&
	( setName("_global."+getCurrentPackageName()) && (val = locateParentForNamed(contextVal.getId(), name, true)) != null ) ) //$NON-NLS-1$
	;

	// if we found it then stake this as our context!
	if (val != null)
	{
	id = val.getId();
	pushName(name);
	lockName();
	}
	}

	return id;
	}

	/**
	* Performs a search for a member with the given name using the
	* given id as the parent variable.
	*
	* If a match is found then, we return the parent variable of
	* the member that matched. The proto chain is optionally traversed.
	*
	* No exceptions are thrown
	*/
	Value locateParentForNamed(long id, String name, boolean traverseProto) throws PlayerDebugException
	{
	StringBuilder sb = new StringBuilder();

	Variable var = null;
	Value val = null;
	try
	{
	var = memberNamed(id, name);

	// see if we need to traverse the proto chain
	while (var == null && traverseProto)
	{
	// first attempt to get __proto__, then resolve name
	Variable proto = memberNamed(id, "__proto__"); //$NON-NLS-1$
	sb.append("__proto__"); //$NON-NLS-1$
	if (proto == null)
	traverseProto = false;
	else
	{
	id = proto.getValue().getId();
	var = memberNamed(id, name);
	if (var == null)
	sb.append('.');
	}
	}
	}
	catch(NoSuchVariableException nsv)
	{
	// don't worry about this one, it means variable with id couldn't be found
	}
	catch(NullPointerException npe)
	{
	// probably no session
	}

	// what we really want is the parent not the child variable
	if (var != null)
	{
	pushName(sb.toString());
	val = getSession().getWorkerSession(m_isolateId).getValue(id);
	}

	return val;
	}

	// variant of locateParentForNamed, whereby we return the child variable
	Variable locateForNamed(long id, String name, boolean traverseProto) throws PlayerDebugException
	{
	Variable var = null;
	Value v = locateParentForNamed(id, name, traverseProto);
	if (v != null)
	{
	try
	{
	var = memberNamed(v.getId(), name);
	}
	catch(NoSuchVariableException nse)
	{
	v = null;
	}
	}

	return var;
	}

	/**
	* Locates the member via a dotted name starting at the given id.
	* It will traverse any and all proto chains if necc. to find the name.
	*/
	Value locate(long startingId, String dottedName, boolean traverseProto) throws PlayerDebugException
	{
	if (dottedName == null)
	return null;

	// first rip apart the dottedName
	StringTokenizer names = new StringTokenizer(dottedName, "."); //$NON-NLS-1$
	Value val = getSession().getWorkerSession(m_isolateId).getValue(startingId);

	while(names.hasMoreTokens() && val != null)
	val = locateForNamed(val.getId(), names.nextToken(), traverseProto).getValue();

	return val;
	}

	/*
	* @see flash.tools.debugger.expression.Context#toValue(java.lang.Object)
	*/
	public Value toValue(Object o)
	{
	// if o is a variable or a value already, then we're done!
	if (o instanceof Value)
	return (Value)o;
	else if (o instanceof Variable)
	return ((Variable)o).getValue();
	else if (o instanceof InternalProperty)
	return DValue.forPrimitive(((InternalProperty)o).m_value, m_isolateId);
	else
	return DValue.forPrimitive(o, m_isolateId);
	}

	public Value toValue()
	{
	return toValue(m_current);
	}

	public Session getSession()
	{
	return m_cache.getSession();
	}

	@Override
	public int getIsolateId() {
	return m_isolateId;
	}
	}