/jEdit/tags/jedit-4-2-pre14/bsh/Name.java

/*****************************************************************************
 *                                                                           *
 *  This file is part of the BeanShell Java Scripting distribution.          *
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 *                                                                           *
 *  The Original Code is BeanShell. The Initial Developer of the Original    *
 *  Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright     *
 *  (C) 2000.  All Rights Reserved.                                          *
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 *                                                                           *
 *  Patrick Niemeyer (pat@pat.net)                                           *
 *  Author of Learning Java, O'Reilly & Associates                           *
 *  http://www.pat.net/~pat/                                                 *
 *                                                                           *
 *****************************************************************************/


package bsh;

import java.lang.reflect.Array;
import java.util.Hashtable;
import java.io.*;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
	What's in a name?  I'll tell you...
	Name() is a somewhat ambiguous thing in the grammar and so is this.
	<p>
	
	This class is a name resolver.  It holds a possibly ambiguous dot 
	separated name and reference to a namespace in which it allegedly lives.  
	It provides methods that attempt to resolve the name to various types of 
	entities: e.g. an Object, a Class, a declared scripted BeanShell method.
	<p>

	Name objects are created by the factory method NameSpace getNameResolver(), 
	which caches them subject to a class namespace change.  This means that 
	we can cache information about various types of resolution here.
	Currently very little if any information is cached.  However with a future
	"optimize" setting that defeats certain dynamic behavior we might be able
	to cache quite a bit.
*/
/*
	<strong>Implementation notes</strong>
	<pre>
	Thread safety: all of the work methods in this class must be synchronized
	because they share the internal intermediate evaluation state.

	Note about invokeMethod():  We could simply use resolveMethod and return
	the MethodInvoker (BshMethod or JavaMethod) however there is no easy way
	for the AST (BSHMehodInvocation) to use this as it doesn't have type
	information about the target to resolve overloaded methods.
	(In Java, overloaded methods are resolved at compile time... here they
	are, of necessity, dynamic).  So it would have to do what we do here
	and cache by signature.  We now do that for the client in Reflect.java.

	Note on this.caller resolution:
	Although references like these do work:

		this.caller.caller.caller...   // works

	the equivalent using successive calls:

		// does *not* work
		for( caller=this.caller; caller != null; caller = caller.caller );

	is prohibited by the restriction that you can only call .caller on a 
	literal	this or caller reference.  The effect is that magic caller 
	reference only works through the current 'this' reference.
	The real explanation is that This referernces do not really know anything
	about their depth on the call stack.  It might even be hard to define
	such a thing...

	For those purposes we provide :

		this.callstack

	</pre>
*/
class Name implements java.io.Serializable
{
	// These do not change during evaluation
	public NameSpace namespace;
	String value = null;
	
	// ---------------------------------------------------------
	// The following instance variables mutate during evaluation and should
	// be reset by the reset() method where necessary

	// For evaluation
	/** Remaining text to evaluate */
	private String evalName;
	/** 
		The last part of the name evaluated.  This is really only used for
	 	this, caller, and super resolution.
	*/
	private String lastEvalName;
	private static String FINISHED = null; // null evalname and we're finished
	private Object evalBaseObject;	// base object for current eval

	private int callstackDepth;		// number of times eval hit 'this.caller'

	//  
	//  End mutable instance variables.
	// ---------------------------------------------------------

	// Begin Cached result structures
	// These are optimizations 

	// Note: it's ok to cache class resolution here because when the class
	// space changes the namespace will discard cached names.

	/** 
		The result is a class 
	*/
	Class asClass;

	/** 
		The result is a static method call on the following class 
	*/
	Class classOfStaticMethod;

	// End Cached result structures

	private void reset() {
		evalName = value;
		evalBaseObject = null;
		callstackDepth = 0;
	}

	/**
		This constructor should *not* be used in general. 
		Use NameSpace getNameResolver() which supports caching.
		@see NameSpace getNameResolver().
	*/
	// I wish I could make this "friendly" to only NameSpace
	Name( NameSpace namespace, String s )
	{
		this.namespace = namespace;
		value = s;
	}

	/**
		Resolve possibly complex name to an object value.

		Throws EvalError on various failures.
		A null object value is indicated by a Primitive.NULL.
		A return type of Primitive.VOID comes from attempting to access
		an undefined variable.

		Some cases:
			myVariable
			myVariable.foo
			myVariable.foo.bar
			java.awt.GridBagConstraints.BOTH
			my.package.stuff.MyClass.someField.someField...

		Interpreter reference is necessary to allow resolution of 
		"this.interpreter" magic field.
		CallStack reference is necessary to allow resolution of 
		"this.caller" magic field.
		"this.callstack" magic field.
	*/
	public Object toObject( CallStack callstack, Interpreter interpreter ) 
		throws UtilEvalError
	{
		return toObject( callstack, interpreter, false );
	}

	/**
		@see toObject()
		@param forceClass if true then resolution will only produce a class.
		This is necessary to disambiguate in cases where the grammar knows
		that we want a class; where in general the var path may be taken.
	*/
	synchronized public Object toObject( 
		CallStack callstack, Interpreter interpreter, boolean forceClass ) 
		throws UtilEvalError
	{
		reset();

		Object obj = null;
		while( evalName != null )
			obj = consumeNextObjectField( 
				callstack, interpreter, forceClass, false/*autoalloc*/  );

		if ( obj == null )
			throw new InterpreterError("null value in toObject()");

		return obj;
	}

	private Object completeRound( 
		String lastEvalName, String nextEvalName, Object returnObject )
	{
		if ( returnObject == null )
			throw new InterpreterError("lastEvalName = "+lastEvalName);
		this.lastEvalName = lastEvalName;
		this.evalName = nextEvalName;
		this.evalBaseObject = returnObject;
		return returnObject;
	}

	/**
		Get the next object by consuming one or more components of evalName.  
		Often this consumes just one component, but if the name is a classname 
		it will consume all of the components necessary to make the class 
		identifier.
	*/
	private Object consumeNextObjectField( 	
		CallStack callstack, Interpreter interpreter, 
		boolean forceClass, boolean autoAllocateThis ) 
		throws UtilEvalError
	{
		/*
			Is it a simple variable name?
			Doing this first gives the correct Java precedence for vars 
			vs. imported class names (at least in the simple case - see
			tests/precedence1.bsh).  It should also speed things up a bit.
		*/
		if ( (evalBaseObject == null && !isCompound(evalName) )
			&& !forceClass ) 
		{
			Object obj = resolveThisFieldReference( 
				callstack, namespace, interpreter, evalName, false );

			if ( obj != Primitive.VOID )
				return completeRound( evalName, FINISHED, obj );
		}

		/*
			Is it a bsh script variable reference?
			If we're just starting the eval of name (no base object)
			or we're evaluating relative to a This type reference check.
		*/
		String varName = prefix(evalName, 1);
		if ( ( evalBaseObject == null || evalBaseObject instanceof This  )
			&& !forceClass ) 
		{
			if ( Interpreter.DEBUG ) 
				Interpreter.debug("trying to resolve variable: " + varName);

			Object obj;
			// switch namespace and special var visibility
			if ( evalBaseObject == null ) {
				obj = resolveThisFieldReference( 
					callstack, namespace, interpreter, varName, false );
			} else {
				obj = resolveThisFieldReference( 
					callstack, ((This)evalBaseObject).namespace, 
					interpreter, varName, true );
			}

			if ( obj != Primitive.VOID ) 
			{
				// Resolved the variable
				if ( Interpreter.DEBUG ) 
					Interpreter.debug( "resolved variable: " + varName + 
					" in namespace: "+namespace);

				return completeRound( varName, suffix(evalName), obj );
			}
		}

		/*
			Is it a class name?
			If we're just starting eval of name try to make it, else fail.
		*/
		if ( evalBaseObject == null ) 
		{
			if ( Interpreter.DEBUG ) 
				Interpreter.debug( "trying class: " + evalName);
			
			/*
				Keep adding parts until we have a class 
			*/
			Class clas = null;
			int i = 1;
			String className = null;
			for(; i <= countParts(evalName); i++)
			{
				className = prefix(evalName, i);
				if ( (clas = namespace.getClass(className)) != null )
					break;
			}
		
			if ( clas != null )  {
				return completeRound(
					className,
					suffix( evalName, countParts(evalName)-i ),
					new ClassIdentifier(clas) 
				);
			}
			// not a class (or variable per above)
			if ( Interpreter.DEBUG ) 
				Interpreter.debug( "not a class, trying var prefix "+evalName );
		}

		// No variable or class found in 'this' type ref.
		// if autoAllocateThis then create one; a child 'this'.
		if ( ( evalBaseObject == null || evalBaseObject instanceof This  )
			&& !forceClass && autoAllocateThis )
		{
			NameSpace targetNameSpace = 
				( evalBaseObject == null ) ?  
					namespace : ((This)evalBaseObject).namespace;
			Object obj = new NameSpace( 
				targetNameSpace, "auto: "+varName ).getThis( interpreter );
			targetNameSpace.setVariable( varName, obj, false );
			return completeRound( varName, suffix(evalName), obj );
		}

		/*
			If we didn't find a class or variable name (or prefix) above
			there are two possibilities:

			- If we are a simple name then we can pass as a void variable 
			reference.
			- If we are compound then we must fail at this point.
		*/
		if ( evalBaseObject == null ) {
			if ( !isCompound(evalName) ) {
				return completeRound( evalName, FINISHED, Primitive.VOID );
			} else
				throw new UtilEvalError(
					"Class or variable not found: " + evalName);
		}

		/*
			--------------------------------------------------------
			After this point we're definitely evaluating relative to
			a base object.
			--------------------------------------------------------
		*/

		/*
			Do some basic validity checks.
		*/

		if ( evalBaseObject == Primitive.NULL) // previous round produced null
			throw new UtilTargetError( new NullPointerException( 
				"Null Pointer while evaluating: " +value ) );

		if ( evalBaseObject == Primitive.VOID) // previous round produced void
			throw new UtilEvalError(
				"Undefined variable or class name while evaluating: "+value);

		if ( evalBaseObject instanceof Primitive)
			throw new UtilEvalError("Can't treat primitive like an object. "+
			"Error while evaluating: "+value);

		/* 
			Resolve relative to a class type
			static field, inner class, ?
		*/
		if ( evalBaseObject instanceof ClassIdentifier ) 
		{
			Class clas = ((ClassIdentifier)evalBaseObject).getTargetClass();
			String field = prefix(evalName, 1);

			// Class qualified 'this' reference from inner class.
			// e.g. 'MyOuterClass.this'
			if ( field.equals("this") )
			{
				// find the enclosing class instance space of the class name
				NameSpace ns = namespace;
				while ( ns != null )
				{
					// getClassInstance() throws exception if not there
					if ( ns.classInstance != null 
						&& ns.classInstance.getClass() == clas 
					)
						return completeRound( 
							field, suffix(evalName), ns.classInstance );
					ns=ns.getParent();
				}
				throw new UtilEvalError(
					"Can't find enclosing 'this' instance of class: "+clas);
			}

			Object obj = null;
			// static field?
			try {
				if ( Interpreter.DEBUG ) 
					Interpreter.debug("Name call to getStaticField, class: " 
						+clas+", field:"+field);
				obj = Reflect.getStaticField(clas, field);
			} catch( ReflectError e ) { 
				if ( Interpreter.DEBUG ) 
					Interpreter.debug("field reflect error: "+e);
			}

			// inner class?
			if ( obj == null ) {
				String iclass = clas.getName()+"$"+field;
				Class c = namespace.getClass( iclass );
				if ( c != null )
					obj = new ClassIdentifier(c);
			}

			if ( obj == null )
				throw new UtilEvalError(
					"No static field or inner class: " 
					+ field + " of " + clas );

			return completeRound( field, suffix(evalName), obj );
		}

		/*
			If we've fallen through here we are no longer resolving to
			a class type.
		*/
		if ( forceClass )
			throw new UtilEvalError( 
				value +" does not resolve to a class name." );

		/* 
			Some kind of field access?
		*/

		String field = prefix(evalName, 1);

		// length access on array? 
		if ( field.equals("length") && evalBaseObject.getClass().isArray() )
		{
			Object obj = new Primitive(Array.getLength(evalBaseObject));
			return completeRound( field, suffix(evalName), obj );
		}

		// Check for field on object 
		// Note: could eliminate throwing the exception somehow
		try {
			Object obj = Reflect.getObjectField(evalBaseObject, field);
			return completeRound( field, suffix(evalName), obj );
		} catch(ReflectError e) { /* not a field */ }
	
		// if we get here we have failed
		throw new UtilEvalError(
			"Cannot access field: " + field + ", on object: " + evalBaseObject);
	}

	/**
		Resolve a variable relative to a This reference.

		This is the general variable resolution method, accomodating special
		fields from the This context.  Together the namespace and interpreter
		comprise the This context.  The callstack, if available allows for the
		this.caller construct.  
		Optionally interpret special "magic" field names: e.g. interpreter.
		<p/>

		@param callstack may be null, but this is only legitimate in special
		cases where we are sure resolution will not involve this.caller.

		@param namespace the namespace of the this reference (should be the
		same as the top of the stack?
	*/
	Object resolveThisFieldReference( 
		CallStack callstack, NameSpace thisNameSpace, Interpreter interpreter, 
		String varName, boolean specialFieldsVisible ) 
		throws UtilEvalError
	{
		if ( varName.equals("this") ) 
		{
			/*
				Somewhat of a hack.  If the special fields are visible (we're
				operating relative to a 'this' type already) dissallow further
				.this references to prevent user from skipping to things like
				super.this.caller
			*/
			if ( specialFieldsVisible )
				throw new UtilEvalError("Redundant to call .this on This type");

			// Allow getThis() to work through BlockNameSpace to the method
			// namespace
	// XXX re-eval this... do we need it?
			This ths = thisNameSpace.getThis( interpreter );
			thisNameSpace= ths.getNameSpace();
			Object result = ths;

			NameSpace classNameSpace = getClassNameSpace( thisNameSpace );
			if ( classNameSpace != null )
			{
				if ( isCompound( evalName ) )
					result = classNameSpace.getThis( interpreter );
				else
					result = classNameSpace.getClassInstance();
			}

			return result;
		}

		/*
			Some duplication for "super".  See notes for "this" above
			If we're in an enclsing class instance and have a superclass
			instance our super is the superclass instance.
		*/
		if ( varName.equals("super") ) 
		{
			//if ( specialFieldsVisible )
			//throw new UtilEvalError("Redundant to call .this on This type");

			// Allow getSuper() to through BlockNameSpace to the method's super
			This ths = thisNameSpace.getSuper( interpreter );
			thisNameSpace = ths.getNameSpace();
			// super is now the closure's super or class instance

	// XXXX re-evaluate this
	// can getSuper work by itself now?
			// If we're a class instance and the parent is also a class instance
			// then super means our parent.
			if ( 
				thisNameSpace.getParent() != null 
				&& thisNameSpace.getParent().isClass
			)
				ths = thisNameSpace.getParent().getThis( interpreter );

			return ths;
		}

		Object obj = null;

		if ( varName.equals("global") )
			obj = thisNameSpace.getGlobal( interpreter );

		if ( obj == null && specialFieldsVisible ) 
		{
			if (varName.equals("namespace"))
				obj = thisNameSpace;
			else if (varName.equals("variables"))
				obj = thisNameSpace.getVariableNames();
			else if (varName.equals("methods"))
				obj = thisNameSpace.getMethodNames();
			else if ( varName.equals("interpreter") )
				if ( lastEvalName.equals("this") )
					obj = interpreter;
				else
					throw new UtilEvalError(
						"Can only call .interpreter on literal 'this'");
		}

		if ( obj == null && specialFieldsVisible && varName.equals("caller") )
		{
			if ( lastEvalName.equals("this") || lastEvalName.equals("caller") ) 
			{
				// get the previous context (see notes for this class)
				if ( callstack == null )
					throw new InterpreterError("no callstack");
				obj = callstack.get( ++callstackDepth ).getThis( 
					interpreter ); 
			}
			else
				throw new UtilEvalError(
				"Can only call .caller on literal 'this' or literal '.caller'");

			// early return
			return obj;
		}

		if ( obj == null && specialFieldsVisible 
			&& varName.equals("callstack") )
		{
			if ( lastEvalName.equals("this") ) 
			{
				// get the previous context (see notes for this class)
				if ( callstack == null )
					throw new InterpreterError("no callstack");
				obj = callstack;
			}
			else
				throw new UtilEvalError(
				"Can only call .callstack on literal 'this'");
		}


		if ( obj == null )
			obj = thisNameSpace.getVariable(varName);

		if ( obj == null )
			throw new InterpreterError("null this field ref:"+varName);

		return obj;
	}

	/**
		@return the enclosing class body namespace or null if not in a class.
	*/
	static NameSpace getClassNameSpace( NameSpace thisNameSpace ) 
	{
		NameSpace classNameSpace = null;
		// is a class instance
		//if ( thisNameSpace.classInstance != null )
		if ( thisNameSpace.isClass )
			return thisNameSpace;

		if ( thisNameSpace.isMethod 
			&& thisNameSpace.getParent() != null 
			//&& thisNameSpace.getParent().classInstance != null
			&& thisNameSpace.getParent().isClass
		)
			return thisNameSpace.getParent();

		return null;
	}

	/**
		Check the cache, else use toObject() to try to resolve to a class
		identifier.  

		@throws ClassNotFoundException on class not found.
		@throws ClassPathException (type of EvalError) on special case of 
		ambiguous unqualified name after super import. 
	*/
	synchronized public Class toClass() 
		throws ClassNotFoundException, UtilEvalError
	{
		if ( asClass != null )
			return asClass;

		reset();

		// "var" means untyped, return null class
		if ( evalName.equals("var") )
			return asClass = null;

		/* Try straightforward class name first */
		Class clas = namespace.getClass( evalName );

		if ( clas == null ) 
		{
			/* 
				Try toObject() which knows how to work through inner classes
				and see what we end up with 
			*/
			Object obj = null;
			try {
				// Null interpreter and callstack references.
				// class only resolution should not require them.
				obj = toObject( null, null, true );  
			} catch ( UtilEvalError  e ) { }; // couldn't resolve it
		
			if ( obj instanceof ClassIdentifier )
				clas = ((ClassIdentifier)obj).getTargetClass();
		}

		if ( clas == null )
			throw new ClassNotFoundException(
				"Class: " + value+ " not found in namespace");

		asClass = clas;
		return asClass;
	}

	/*
	*/
	synchronized public LHS toLHS( 
		CallStack callstack, Interpreter interpreter )
		throws UtilEvalError
	{
		// Should clean this up to a single return statement
		reset();
		LHS lhs;

		// Simple (non-compound) variable assignment e.g. x=5;
		if ( !isCompound(evalName) ) 
		{
			if ( evalName.equals("this") )
				throw new UtilEvalError("Can't assign to 'this'." );

			// Interpreter.debug("Simple var LHS...");
			lhs = new LHS( namespace, evalName, false/*bubble up if allowed*/);
			return lhs;
		}

		// Field e.g. foo.bar=5;
		Object obj = null;
		try {
			while( evalName != null && isCompound( evalName ) )
			{
				obj = consumeNextObjectField( callstack, interpreter, 
					false/*forcclass*/, true/*autoallocthis*/ );
			}
		} 
		catch( UtilEvalError e ) {
			throw new UtilEvalError( "LHS evaluation: " + e.getMessage() );
		}

		// Finished eval and its a class.
		if ( evalName == null && obj instanceof ClassIdentifier )
			throw new UtilEvalError("Can't assign to class: " + value );

		if ( obj == null )
			throw new UtilEvalError("Error in LHS: " + value );

		// e.g. this.x=5;  or someThisType.x=5;
		if ( obj instanceof This )
		{
			// dissallow assignment to magic fields
			if ( 
				evalName.equals("namespace")
				|| evalName.equals("variables")
				|| evalName.equals("methods")
				|| evalName.equals("caller")
			)
				throw new UtilEvalError(
					"Can't assign to special variable: "+evalName );

			Interpreter.debug("found This reference evaluating LHS");
			/*
				If this was a literal "super" reference then we allow recursion
				in setting the variable to get the normal effect of finding the
				nearest definition starting at the super scope.  On any other
				resolution qualified by a 'this' type reference we want to set
				the variable directly in that scope. e.g. this.x=5;  or 
				someThisType.x=5;
				
				In the old scoping rules super didn't do this.
			*/
			boolean localVar = !lastEvalName.equals("super");
			return new LHS( ((This)obj).namespace, evalName, localVar );
		}

		if ( evalName != null )
		{
			try {
				if ( obj instanceof ClassIdentifier ) 
				{
					Class clas = ((ClassIdentifier)obj).getTargetClass();
					lhs = Reflect.getLHSStaticField(clas, evalName);
					return lhs;
				} else {
					lhs = Reflect.getLHSObjectField(obj, evalName);
					return lhs;
				}
			} catch(ReflectError e) {
				throw new UtilEvalError("Field access: "+e);
			}
		}

		throw new InterpreterError("Internal error in lhs...");
	}
	
    /**
		Invoke the method identified by this name.
		Performs caching of method resolution using SignatureKey.
		<p>

        Name contains a wholely unqualfied messy name; resolve it to 
		( object | static prefix ) + method name and invoke.
		<p>

        The interpreter is necessary to support 'this.interpreter' references
		in the called code. (e.g. debug());
		<p>

		<pre>
        Some cases:

            // dynamic
            local();
            myVariable.foo();
            myVariable.bar.blah.foo();
            // static
            java.lang.Integer.getInteger("foo");
		</pre>
    */
    public Object invokeMethod(
		Interpreter interpreter, Object[] args, CallStack callstack,
		SimpleNode callerInfo
	)
        throws UtilEvalError, EvalError, ReflectError, InvocationTargetException
    {
        String methodName = Name.suffix(value, 1);
		BshClassManager bcm = interpreter.getClassManager();
		NameSpace namespace = callstack.top();

		// Optimization - If classOfStaticMethod is set then we have already 
		// been here and determined that this is a static method invocation.
		// Note: maybe factor this out with path below... clean up.
        if ( classOfStaticMethod != null )
		{
			return Reflect.invokeStaticMethod( 
				bcm, classOfStaticMethod, methodName, args );
		}

		if ( !Name.isCompound(value) )
			return invokeLocalMethod( 
				interpreter, args, callstack, callerInfo );

		// Note: if we want methods declared inside blocks to be accessible via
		// this.methodname() inside the block we could handle it here as a
		// special case.  See also resolveThisFieldReference() special handling
		// for BlockNameSpace case.  They currently work via the direct name
		// e.g. methodName().

        String prefix = Name.prefix(value);

		// Superclass method invocation? (e.g. super.foo())
		if ( prefix.equals("super") && Name.countParts(value) == 2 )
		{
			NameSpace classNameSpace = getClassNameSpace( namespace );
			if ( classNameSpace != null )
			{
				Object instance = classNameSpace.getClassInstance();
				return ClassGenerator.getClassGenerator()
					.invokeSuperclassMethod( bcm, instance, methodName, args );
			}
		}

        // Find target object or class identifier
        Name targetName = namespace.getNameResolver( prefix );
        Object obj = targetName.toObject( callstack, interpreter );

		if ( obj == Primitive.VOID ) 
			throw new UtilEvalError( "Attempt to resolve method: "+methodName
					+"() on undefined variable or class name: "+targetName);

        // if we've got an object, resolve the method
        if ( !(obj instanceof ClassIdentifier) ) {

            if (obj instanceof Primitive) {

                if (obj == Primitive.NULL)
                    throw new UtilTargetError( new NullPointerException( 
						"Null Pointer in Method Invocation" ) );

                // some other primitive
                // should avoid calling methods on primitive, as we do
                // in Name (can't treat primitive like an object message)
                // but the hole is useful right now.
				if ( Interpreter.DEBUG )
                	interpreter.debug(
					"Attempt to access method on primitive..." 
					+ " allowing bsh.Primitive to peek through for debugging");
            }

            // found an object and it's not an undefined variable
            return Reflect.invokeObjectMethod(
				obj, methodName, args, interpreter, callstack, callerInfo );
        }

		// It's a class

        // try static method
        if ( Interpreter.DEBUG ) 
        	Interpreter.debug("invokeMethod: trying static - " + targetName);

        Class clas = ((ClassIdentifier)obj).getTargetClass();

		// cache the fact that this is a static method invocation on this class
		classOfStaticMethod = clas;
		
        if ( clas != null )
			return Reflect.invokeStaticMethod( bcm, clas, methodName, args );

        // return null; ???
		throw new UtilEvalError("invokeMethod: unknown target: " + targetName);
    }

	/**
		Invoke a locally declared method or a bsh command.
		If the method is not already declared in the namespace then try
		to load it as a resource from the imported command path (e.g.
		/bsh/commands)
	*/
	/*
		Note: the bsh command code should probably not be here...  we need to
		scope it by the namespace that imported the command... so it probably
		needs to be integrated into NameSpace.
	*/
    private Object invokeLocalMethod( 
		Interpreter interpreter, Object[] args, CallStack callstack,
		SimpleNode callerInfo
	)
        throws EvalError/*, ReflectError, InvocationTargetException*/
    {
        if ( Interpreter.DEBUG ) 
        	Interpreter.debug( "invokeLocalMethod: " + value );
		if ( interpreter == null )
			throw new InterpreterError(
				"invokeLocalMethod: interpreter = null");

		String commandName = value;
		Class [] argTypes = Types.getTypes( args );

        // Check for existing method
        BshMethod meth = null;
		try {
			meth = namespace.getMethod( commandName, argTypes );
		} catch ( UtilEvalError e ) {
			throw e.toEvalError(
				"Local method invocation", callerInfo, callstack );
		}

		// If defined, invoke it
        if ( meth != null )
			return meth.invoke( args, interpreter, callstack, callerInfo );

		BshClassManager bcm = interpreter.getClassManager();

		// Look for a BeanShell command

		Object commandObject;
		try {
			commandObject = namespace.getCommand( 
				commandName, argTypes, interpreter );
		} catch ( UtilEvalError e ) {
			throw e.toEvalError("Error loading command: ", 
				callerInfo, callstack );
		}

		// should try to print usage here if nothing found
		if ( commandObject == null )
		{
			// Look for a default invoke() handler method in the namespace
			// Note: this code duplicates that in This.java... should it?
			// Call on 'This' can never be a command
			BshMethod invokeMethod = null;
			try {
				invokeMethod = namespace.getMethod( 
					"invoke", new Class [] { null, null } );
			} catch ( UtilEvalError e ) {
				throw e.toEvalError(
					"Local method invocation", callerInfo, callstack );
			}

			if ( invokeMethod != null )
				return invokeMethod.invoke( 
					new Object [] { commandName, args }, 
					interpreter, callstack, callerInfo );

            throw new EvalError( "Command not found: " 
				+StringUtil.methodString( commandName, argTypes ), 
				callerInfo, callstack );
		}

		if ( commandObject instanceof BshMethod )
			return ((BshMethod)commandObject).invoke( 
				args, interpreter, callstack, callerInfo );

		if ( commandObject instanceof Class )
			try {
				return Reflect.invokeCompiledCommand( 
					((Class)commandObject), args, interpreter, callstack );
			} catch ( UtilEvalError e ) {
				throw e.toEvalError("Error invoking compiled command: ",
				callerInfo, callstack );
			}

		throw new InterpreterError("invalid command type");
    }

/*
	private String getHelp( String name )
		throws UtilEvalError
	{
		try {
			// should check for null namespace here
			return get( "bsh.help."+name, null/interpreter/ );
		} catch ( Exception e ) {
			return "usage: "+name;
		}
	}

	private String getHelp( Class commandClass )
		throws UtilEvalError
	{
        try {
            return (String)Reflect.invokeStaticMethod(
				null/bcm/, commandClass, "usage", null );
        } catch( Exception e )
			return "usage: "+name;
		}
	}
*/

	// Static methods that operate on compound ('.' separated) names
	// I guess we could move these to StringUtil someday

	public static boolean isCompound(String value)
	{
		return value.indexOf('.') != -1 ;
		//return countParts(value) > 1;
	}

	static int countParts(String value)
	{
		if(value == null)
			return 0;

		int count = 0;
		int index = -1;
		while((index = value.indexOf('.', index + 1)) != -1)
			count++;
		return count + 1;
	}

	static String prefix(String value)
	{
		if(!isCompound(value))
			return null;

		return prefix(value, countParts(value) - 1);
	}

	static String prefix(String value, int parts)
	{
		if (parts < 1 )
			return null;

		int count = 0;
		int index = -1;

		while( ((index = value.indexOf('.', index + 1)) != -1) 
			&& (++count < parts) )
		{ ; }

		return (index == -1) ? value : value.substring(0, index);
	}

	static String suffix(String name)
	{
		if(!isCompound(name))
			return null;

		return suffix(name, countParts(name) - 1);
	}

	public static String suffix(String value, int parts)
	{
		if (parts < 1)
			return null;

		int count = 0;
		int index = value.length() + 1;

		while ( ((index = value.lastIndexOf('.', index - 1)) != -1) 
			&& (++count < parts) );

		return (index == -1) ? value : value.substring(index + 1);
	}

	// end compound name routines


	public String toString() { return value; }

}