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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/ *
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* Sun Public License Notice: *
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* The contents of this file are subject to the Sun Public License Version *
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* Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright *
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* Patrick Niemeyer ([email protected]) *
* Author of Learning Java, O'Reilly & Associates *
* http://www.pat.net/~pat/ *
* *
*****************************************************************************/
package bsh;
/**
* Implement binary expressions... Note: this is too complicated... need some
* cleanup and simplification.
*
* @see Primitive#binaryOperation(Object, Object, int)
*/
class BSHBinaryExpression extends SimpleNode implements ParserConstants {
private static final long serialVersionUID = 1L;
public int kind;
BSHBinaryExpression(int id) {
super(id);
}
public Object eval(CallStack callstack, Interpreter interpreter) throws EvalError {
Object lhs = ((SimpleNode) jjtGetChild(0)).eval(callstack, interpreter);
/*
* Doing instanceof? Next node is a type.
*/
if (kind == INSTANCEOF) {
// null object ref is not instance of any type
if (lhs == Primitive.NULL)
return new Primitive(false);
Class rhs = ((BSHType) jjtGetChild(1)).getType(callstack, interpreter);
/*
* // primitive (number or void) cannot be tested for instanceof if
* (lhs instanceof Primitive) throw new
* EvalError("Cannot be instance of primitive type." );
*/
/*
* Primitive (number or void) is not normally an instanceof
* anything. But for internal use we'll test true for the
* bsh.Primitive class. i.e. (5 instanceof bsh.Primitive) will be
* true
*/
if (lhs instanceof Primitive)
if (rhs == bsh.Primitive.class)
return new Primitive(true);
else
return new Primitive(false);
// General case - performe the instanceof based on
// assignability
boolean ret = Types.isJavaBaseAssignable(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 for boolean short-circuiting.
/*
* Are both the lhs and rhs either wrappers or primitive values? do
* binary op
*/
boolean isLhsWrapper = isWrapper(lhs);
Object rhs = ((SimpleNode) jjtGetChild(1)).eval(callstack, 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
try {
return Primitive.binaryOperation(lhs, rhs, kind);
} catch (UtilEvalError e) {
throw e.toEvalError(this, callstack);
}
}
/*
* Doing the following makes it hard to use untyped vars... e.g. if (
* arg == null ) ...what if arg is a primitive? The answer is that we
* should test only if the var is typed...? need to get that info
* here...
*
* else { // Do we have a mixture of primitive values and non-primitives
* ? // (primitiveValue = not null, not void)
*
* int primCount = 0; if ( isPrimitiveValue( lhs ) ) ++primCount; if (
* isPrimitiveValue( rhs ) ) ++primCount;
*
* if ( primCount > 1 ) // both primitive types, should have been
* handled above throw new InterpreterError("should not be here"); else
* if ( primCount == 1 ) // mixture of one and the other throw new
* EvalError("Operator: '" + tokenImage[kind]
* +"' inappropriate for object / primitive combination.", this,
* callstack ); // else fall through to handle both non-primitive types
* // end check for primitive and non-primitive mix }
*/
/*
* Treat lhs and rhs as arbitrary objects and do the operation.
* (including NULL and VOID represented by their Primitive types)
*/
// System.out.println("binary op arbitrary obj: {"+lhs+"},
// {"+rhs+"}");
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 variable, class, or 'void' literal", this, callstack);
else if (lhs == Primitive.NULL || rhs == Primitive.NULL)
throw new EvalError("illegal use of null value or 'null' literal", this, callstack);
throw new EvalError("Operator: '" + tokenImage[kind] + "' inappropriate for objects", this, callstack);
}
}
/*
* object is a non-null and 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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