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/*****************************************************************************
* *
* This file is part of the BeanShell Java Scripting distribution. *
* Documentation and updates may be found at http://www.beanshell.org/ *
* *
* Sun Public License Notice: *
* *
* The contents of this file are subject to the Sun Public License Version *
* 1.0 (the "License"); you may not use this file except in compliance with *
* the License. A copy of the License is available at http://www.sun.com *
* *
* 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. *
* *
* GNU Public License Notice: *
* *
* Alternatively, the contents of this file may be used under the terms of *
* the GNU Lesser General Public License (the "LGPL"), in which case the *
* provisions of LGPL are applicable instead of those above. If you wish to *
* allow use of your version of this file only under the terms of the LGPL *
* and not to allow others to use your version of this file under the SPL, *
* indicate your decision by deleting the provisions above and replace *
* them with the notice and other provisions required by the LGPL. If you *
* do not delete the provisions above, a recipient may use your version of *
* this file under either the SPL or the LGPL. *
* *
* Patrick Niemeyer (pat@pat.net) *
* Author of Learning Java, O'Reilly & Associates *
* http://www.pat.net/~pat/ *
* *
*****************************************************************************/
package bsh;
/**
This class needs logic to prevent the right hand side of boolean logical
expressions from being naively evaluated... e.g. for "foo && bar" bar
should not be evaluated in the case where foo is true.
*/
class BSHBinaryExpression extends SimpleNode
implements InterpreterConstants
{
public int kind;
BSHBinaryExpression(int id) { super(id); }
public Object eval(NameSpace namespace, Interpreter interpreter) throws EvalError
{
Object lhs = ((SimpleNode)jjtGetChild(0)).eval(namespace, interpreter);
/*
Doing instanceof? Next node is a type.
*/
if(kind == INSTANCEOF)
{
if(lhs instanceof Primitive)
{
// primitive can't be instance of anything, right?
return new Primitive(false);
}
Class rhs = ((BSHType)jjtGetChild(1)).getType(namespace);
boolean ret = (Reflect.isAssignableFrom(rhs, lhs.getClass()));
return new Primitive(ret);
}
// The following two boolean checks were tacked on.
// This could probably be smoothed out.
/*
Look ahead and short circuit evaluation of the rhs if:
we're a boolean AND and the lhs is false.
*/
if ( kind == BOOL_AND || kind == BOOL_ANDX ) {
Object obj = lhs;
if ( isPrimitiveValue(lhs) )
obj = ((Primitive)lhs).getValue();
if ( obj instanceof Boolean &&
( ((Boolean)obj).booleanValue() == false ) )
return new Primitive(false);
}
/*
Look ahead and short circuit evaluation of the rhs if:
we're a boolean AND and the lhs is false.
*/
if ( kind == BOOL_OR || kind == BOOL_ORX ) {
Object obj = lhs;
if ( isPrimitiveValue(lhs) )
obj = ((Primitive)lhs).getValue();
if ( obj instanceof Boolean &&
( ((Boolean)obj).booleanValue() == true ) )
return new Primitive(true);
}
// end stuff that was tacked on.
/*
Are both the lhs and rhs either wrappers or primitive values?
*/
boolean isLhsWrapper = isWrapper( lhs );
Object rhs = ((SimpleNode)jjtGetChild(1)).eval(namespace, interpreter);
boolean isRhsWrapper = isWrapper( rhs );
if ( ( isLhsWrapper || isPrimitiveValue( lhs ) ) &&
( isRhsWrapper || isPrimitiveValue( rhs ) ) )
{
// Special case for EQ on two wrapper objects
if ( isLhsWrapper && isRhsWrapper && kind == EQ ) {
/*
Don't auto-unwrap wrappers (preserve identity semantics)
FALL THROUGH TO OBJECT OPERATIONS BELOW.
*/
} else
return primitiveBinaryOperation(lhs, rhs, kind);
}
/*
Treat lhs and rhs as arbitrary objects
*/
switch(kind)
{
case EQ:
return new Primitive((lhs == rhs));
case NE:
return new Primitive((lhs != rhs));
case PLUS:
if(lhs instanceof String || rhs instanceof String)
return lhs.toString() + rhs.toString();
// FALL THROUGH TO DEFAULT CASE!!!
default:
if(lhs instanceof Primitive || rhs instanceof Primitive)
if(lhs == Primitive.VOID || rhs == Primitive.VOID)
throw new EvalError("illegal use of undefined object or 'void' literal", this);
else if(lhs == Primitive.NULL || rhs == Primitive.NULL)
throw new EvalError("illegal use of null object or 'null' literal", this);
throw new EvalError("Operator: '" + tokenImage[kind] +
"' inappropriate for objects", this);
}
}
public static Object primitiveBinaryOperation(Object obj1, Object obj2, int kind)
throws EvalError
{
if(obj1 instanceof Primitive && obj2 instanceof Primitive)
return Primitive.binaryOperation((Primitive)obj1, (Primitive)obj2, kind);
// if one operand is a primitive wrapper and the other is a primitive
// then wrap the primitive in a primitive wrapper.
if(obj1 instanceof Primitive)
obj1 = ((Primitive)obj1).getValue();
if(obj2 instanceof Primitive)
obj2 = ((Primitive)obj2).getValue();
Class lhsType = obj1.getClass();
Class rhsType = obj2.getClass();
Object[] operands = Primitive.promotePrimitives(obj1, obj2);
Object lhs = operands[0];
Object rhs = operands[1];
if(lhs.getClass() != rhs.getClass())
throw new EvalError("type mismatch in operator. " + lhsType +
" cannot be matched with " + rhsType );
if(lhs instanceof Boolean)
return Primitive.booleanBinaryOperation((Boolean)lhs, (Boolean)rhs, kind);
else if(lhs instanceof Integer)
{
Object result = Primitive.intBinaryOperation((Integer)lhs, (Integer)rhs, kind);
/*
if(result instanceof Number && lhsType == rhsType)
{
Number number = (Number)result;
if(lhsType == Byte.TYPE)
result = new Byte(number.byteValue());
if(lhsType == Short.TYPE)
result = new Short(number.shortValue());
if(lhsType == Character.TYPE)
result = new Character((char)number.intValue());
}
*/
return result;
}
else if(lhs instanceof Long)
return Primitive.longBinaryOperation((Long)lhs, (Long)rhs, kind);
else if(lhs instanceof Float)
return Primitive.floatBinaryOperation((Float)lhs, (Float)rhs, kind);
else if(lhs instanceof Double)
return Primitive.doubleBinaryOperation((Double)lhs, (Double)rhs, kind);
else
throw new EvalError("Invalid types in binary operator" );
}
/*
object is a non-null non-void Primitive type
*/
private boolean isPrimitiveValue( Object obj ) {
return ( (obj instanceof Primitive) && (obj != Primitive.VOID &&
obj != Primitive.NULL) );
}
/*
object is a java.lang wrapper for boolean, char, or number type
*/
private boolean isWrapper( Object obj ) {
return ( obj instanceof Boolean ||
obj instanceof Character || obj instanceof Number );
}
}
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