/jEdit/tags/jedit-4-0-pre3/bsh/BSHTypedVariableDeclaration.java

/*****************************************************************************
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 *  This file is part of the BeanShell Java Scripting distribution.          *
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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 BSHTypedVariableDeclaration extends SimpleNode
{
    public boolean isFinal;
	
    BSHTypedVariableDeclaration(int id) { super(id); }

	/**
		evaluate the type and one or more variable declarators, e.g.:
			int a, b=5, c;

	*/
    public Object eval( CallStack callstack, Interpreter interpreter)  
		throws EvalError
    {
		try {
			NameSpace namespace = callstack.top();
			BSHType typeNode = ((BSHType)jjtGetChild(0));
			Class type = typeNode.getType( namespace );

			int n = jjtGetNumChildren();
			for (int i = 1; i < n; i++)
			{
				BSHVariableDeclarator dec = 
					(BSHVariableDeclarator)jjtGetChild(i);

				// Type node is passed down the chain for array initializers
				// which need it under some circumstances
				Object value = dec.eval( typeNode, callstack, interpreter);

				// simple declaration with no value, e.g. int a;
				// null in value will prompt defaulting in setTypedVariable
				if ( value == Primitive.VOID ) 
					value = null;
				else 
				// true null value being assigned
				if ( value == Primitive.NULL ) {
					// leave as Primitive.NULL
				}
				else
				// allow specific numeric conversions on declaration
				if ( canCastToDeclaredType( value, type ) )
					value = BSHCastExpression.castObject( value, type );
				else {
					// leave value alone
				}

				namespace.setTypedVariable( dec.name, type, value, isFinal );
			}
		} catch ( EvalError e ) {
			e.reThrow( "Typed variable declaration", this );
		}

        return Primitive.VOID;
    }

	/**
		Determine if a cast would be legitimate in order to handle the 
		special cases where a numeric declared var is assigned a type larger 
		than it can handle. (JLS cite??)

			byte b = 5;
			byte b1 = 5*10;

		Normally the above would be int types.
	*/
	/*
		Note: in theory this probably shouldn't be considered a cast, but 
		should be taken into account during literal and expression evaluation
		where the result type is guided by the context.  However this is much
		simpler to deal with and there is no other use for the other that I'm
		aware of.
	*/
	boolean canCastToDeclaredType( Object value, Class toType ) {
		if ( !(value instanceof Primitive) )
			return false;
		Class fromType = ((Primitive)value).getType();
		
		if ( (toType==Byte.TYPE || toType==Short.TYPE || toType==Character.TYPE)
			&& fromType == Integer.TYPE 
		)
			return true;
		else
			return false;
	}

}