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

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Java | 122 lines | 47 code | 13 blank | 62 comment | 14 complexity | 183fb938a92dad031ae1775f4d279c8a MD5 | raw file
  1/*****************************************************************************
  2 *                                                                           *
  3 *  This file is part of the BeanShell Java Scripting distribution.          *
  4 *  Documentation and updates may be found at http://www.beanshell.org/      *
  5 *                                                                           *
  6 *  Sun Public License Notice:                                               *
  7 *                                                                           *
  8 *  The contents of this file are subject to the Sun Public License Version  *
  9 *  1.0 (the "License"); you may not use this file except in compliance with *
 10 *  the License. A copy of the License is available at http://www.sun.com    * 
 11 *                                                                           *
 12 *  The Original Code is BeanShell. The Initial Developer of the Original    *
 13 *  Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright     *
 14 *  (C) 2000.  All Rights Reserved.                                          *
 15 *                                                                           *
 16 *  GNU Public License Notice:                                               *
 17 *                                                                           *
 18 *  Alternatively, the contents of this file may be used under the terms of  *
 19 *  the GNU Lesser General Public License (the "LGPL"), in which case the    *
 20 *  provisions of LGPL are applicable instead of those above. If you wish to *
 21 *  allow use of your version of this file only under the  terms of the LGPL *
 22 *  and not to allow others to use your version of this file under the SPL,  *
 23 *  indicate your decision by deleting the provisions above and replace      *
 24 *  them with the notice and other provisions required by the LGPL.  If you  *
 25 *  do not delete the provisions above, a recipient may use your version of  *
 26 *  this file under either the SPL or the LGPL.                              *
 27 *                                                                           *
 28 *  Patrick Niemeyer (pat@pat.net)                                           *
 29 *  Author of Learning Java, O'Reilly & Associates                           *
 30 *  http://www.pat.net/~pat/                                                 *
 31 *                                                                           *
 32 *****************************************************************************/
 33
 34
 35package bsh;
 36
 37class BSHTypedVariableDeclaration extends SimpleNode
 38{
 39    public boolean isFinal;
 40	
 41    BSHTypedVariableDeclaration(int id) { super(id); }
 42
 43	/**
 44		evaluate the type and one or more variable declarators, e.g.:
 45			int a, b=5, c;
 46
 47	*/
 48    public Object eval( CallStack callstack, Interpreter interpreter)  
 49		throws EvalError
 50    {
 51		try {
 52			NameSpace namespace = callstack.top();
 53			BSHType typeNode = ((BSHType)jjtGetChild(0));
 54			Class type = typeNode.getType( namespace );
 55
 56			int n = jjtGetNumChildren();
 57			for (int i = 1; i < n; i++)
 58			{
 59				BSHVariableDeclarator dec = 
 60					(BSHVariableDeclarator)jjtGetChild(i);
 61
 62				// Type node is passed down the chain for array initializers
 63				// which need it under some circumstances
 64				Object value = dec.eval( typeNode, callstack, interpreter);
 65
 66				// simple declaration with no value, e.g. int a;
 67				// null in value will prompt defaulting in setTypedVariable
 68				if ( value == Primitive.VOID ) 
 69					value = null;
 70				else 
 71				// true null value being assigned
 72				if ( value == Primitive.NULL ) {
 73					// leave as Primitive.NULL
 74				}
 75				else
 76				// allow specific numeric conversions on declaration
 77				if ( canCastToDeclaredType( value, type ) )
 78					value = BSHCastExpression.castObject( value, type );
 79				else {
 80					// leave value alone
 81				}
 82
 83				namespace.setTypedVariable( dec.name, type, value, isFinal );
 84			}
 85		} catch ( EvalError e ) {
 86			e.reThrow( "Typed variable declaration", this );
 87		}
 88
 89        return Primitive.VOID;
 90    }
 91
 92	/**
 93		Determine if a cast would be legitimate in order to handle the 
 94		special cases where a numeric declared var is assigned a type larger 
 95		than it can handle. (JLS cite??)
 96
 97			byte b = 5;
 98			byte b1 = 5*10;
 99
100		Normally the above would be int types.
101	*/
102	/*
103		Note: in theory this probably shouldn't be considered a cast, but 
104		should be taken into account during literal and expression evaluation
105		where the result type is guided by the context.  However this is much
106		simpler to deal with and there is no other use for the other that I'm
107		aware of.
108	*/
109	boolean canCastToDeclaredType( Object value, Class toType ) {
110		if ( !(value instanceof Primitive) )
111			return false;
112		Class fromType = ((Primitive)value).getType();
113		
114		if ( (toType==Byte.TYPE || toType==Short.TYPE || toType==Character.TYPE)
115			&& fromType == Integer.TYPE 
116		)
117			return true;
118		else
119			return false;
120	}
121
122}