/*****************************************************************************
* *
* 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;
/**
* Implement binary expressions... Note: this is too complicated... need some
* cleanup and simplification.
*
* @see Primitive.binaryOperation
*/
class BSHBinaryExpression extends SimpleNode implements ParserConstants {
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) {
/* VASSAL - Try again, converting both sides to Strings, report the original error if it fails */
try {
return Primitive.binaryOperation(lhs.toString(), rhs.toString(), kind);
}
catch (UtilEvalError e2) {
throw e.toEvalError(this, callstack);
}
}
}
}
/*
* VASSAL Special cases
* 1. If one side is an Integer and the other is the null String, replace
* the null String with a 0.
* 2. If one side is a Primitive and the other side is a non-null String, convert the Primitive
* to a String so that + will work.
*/
else {
// lhs in an Integer and rhs is the null string
if (lhs instanceof Primitive && ((Primitive) lhs).getValue() instanceof Integer && rhs.equals("") ) {
try {
return Primitive.binaryOperation(lhs, new Primitive(0), kind);
}
catch (UtilEvalError e) {
throw e.toEvalError(this, callstack);
}
}
// lhs is the null string and rhs is an Integer
else if (rhs instanceof Primitive && ((Primitive) rhs).getValue() instanceof Integer && lhs.equals("") ) {
try {
return Primitive.binaryOperation(new Primitive(0), rhs, kind);
}
catch (UtilEvalError e) {
throw e.toEvalError(this, callstack);
}
}
// lhs is primitive, right hand side is string
else if ((isLhsWrapper || isPrimitiveValue(lhs)) && rhs instanceof String) {
try {
return Primitive.binaryOperation(lhs.toString(), rhs, kind);
}
catch (UtilEvalError e) {
throw e.toEvalError(this, callstack);
}
}
// lhs is string, rhs is primitiv
else if ((isRhsWrapper || isPrimitiveValue(rhs)) && lhs instanceof String) {
try {
return Primitive.binaryOperation(lhs, rhs.toString(), 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+"}");
/*
* VASSAL - Handle Strings as a type of Primitive - allow comparison operators on Strings.
*/
if (lhs instanceof String && rhs instanceof String) {
try {
return Primitive.binaryOperation(lhs, rhs, kind);
}
catch (UtilEvalError e) {
throw e.toEvalError(this, callstack);
}
}
else {
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);
}
}
/*
* VASSAL - Convert Strings to a Primitive if possible
*/
private Object convert(String obj) {
if (obj.equals("true")) {
return new Primitive(true);
}
else if (obj.equals("false")) {
return new Primitive(false);
}
int i;
try {
i = Integer.parseInt(obj);
}
catch (NumberFormatException e) {
// Not an Error
return null;
}
return new Primitive(i);
}
/*
* 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);
}
}