/jEdit/tags/jedit-4-2-pre4/bsh/BSHLHSPrimaryExpression.java

/*****************************************************************************
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 *  Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright     *
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 *  Patrick Niemeyer (pat@pat.net)                                           *
 *  Author of Learning Java, O'Reilly & Associates                           *
 *  http://www.pat.net/~pat/                                                 *
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 *****************************************************************************/


package bsh;

class BSHLHSPrimaryExpression extends SimpleNode
{
	BSHLHSPrimaryExpression(int id) { super(id); }

	/**
		Evaluate the expression to an object.
	*/
	public Object eval(CallStack callstack, Interpreter interpreter)  
		throws EvalError
	{
		try {
			return toLHS( callstack, interpreter ).getValue();
		} catch ( UtilEvalError e ) {
			throw e.toEvalError( this, callstack );
		}
	}

	public LHS toLHS(CallStack callstack, Interpreter interpreter) 
		throws EvalError
	{
		/*
			Get the prefix, which may be either an ambiguous name or a
			method invocation.  

			The method invocation bit here is somewhat of a hack to handle 
			the fact that we have moved prefix method invocation into the 
			PrimaryPrefix in order to get it to always produce an object type.

			This is too complicated.
		*/
		int childNum = 0;
		SimpleNode prefixNode = (SimpleNode)jjtGetChild(childNum++);
		Object prefixValue = null;
		LHS lhs = null;
		if ( prefixNode instanceof BSHAmbiguousName )
			lhs = ((BSHAmbiguousName)prefixNode).toLHS( callstack, interpreter);
		else
			// Currently the only case is for BSHMethodInvocation
			prefixValue = 
				((SimpleNode)prefixNode).eval( callstack, interpreter);

		// If the prefix is an object and not an LHS it requires at least
		// one suffix to make an LHS
		// Currently the only case is for BSHMethodInvocation
		if ( prefixValue != null )
			lhs = ((BSHLHSPrimarySuffix)jjtGetChild(childNum++)).doLHSSuffix(
				prefixValue, callstack, interpreter);

		// Apply the suffixes
		int numChildren = jjtGetNumChildren(); 
		while ( childNum<numChildren )
			try {
				lhs = ((BSHLHSPrimarySuffix)jjtGetChild(childNum++))
					.doLHSSuffix( lhs.getValue(), callstack, interpreter);
			} catch ( UtilEvalError e ) {
				throw e.toEvalError( this, callstack  );
			}

		return lhs;
	}
}