CPDecimalCompare Problem

CPDecimalCompare Problem

/*
 * AppController.j
 * CPDecimalTest
 *
 * Created by You on January 11, 2013.
 * Copyright 2013, Your Company All rights reserved.
 */

var debugCPDecimalCompare;

@import <Foundation/CPObject.j>


@implementation AppController : CPObject
{

}

- (void)applicationDidFinishLaunching:(CPNotification)aNotification
{
    var theWindow = [[CPWindow alloc] initWithContentRect:CGRectMakeZero() styleMask:CPBorderlessBridgeWindowMask],
        contentView = [theWindow contentView];

    var label = [[CPTextField alloc] initWithFrame:CGRectMakeZero()];

    [label setStringValue:@"Open the console!"];
    [label setFont:[CPFont boldSystemFontOfSize:24.0]];

    [label sizeToFit];

    [label setAutoresizingMask:CPViewMinXMargin | CPViewMaxXMargin | CPViewMinYMargin | CPViewMaxYMargin];
    [label setCenter:[contentView center]];

    [contentView addSubview:label];

    [theWindow orderFront:self];

    debugCPDecimalCompare = NO;
    console.log("The following tests show that [CPDecimalNumber -compare:] incorrectly evaluates numbers in the range 0 to 0.999999... as less than zero.");
    [self isNegative:@"1"];
    [self isNegative:@"0.99999"];
    [self isNegative:@"0.25"];
    [self isNegative:@"0.0"];
    [self isNegative:@"0"];
    [self isNegative:@"0.25"];
    [self isNegative:@"2.25"];
    [self isNegative:@"-2.25"];

    console.log("\nEnabling debug flag to log CPDecimalCompare internals");
    debugCPDecimalCompare = YES;

    console.log("\nThe following is WRONG");
    [self isNegative:@"0.25"];

    console.log("\nThe following is CORRECT");
    [self isNegative:@"1.25"];

    console.log("\nFor some reason the rightOperand._mantissa.length of [CPDecimalNumber zero] is different over the last two calls..");
}

- (void)isNegative:(CPString)stringRepresentationOfNumber
{
    var decimalNumber = [CPDecimalNumber decimalNumberWithString:stringRepresentationOfNumber],
        comparisonResult = [decimalNumber compare:[CPDecimalNumber zero]];

    console.log("\nEvaluating: is " + [decimalNumber stringValue] + " < 0?");

    if (comparisonResult === CPOrderedAscending)
    {
        console.log("\tCappuccino thinks " + stringRepresentationOfNumber + " is less than zero");
    }
    else if (comparisonResult === CPOrderedSame)
    {
        console.log("\tCappuccino thinks " + stringRepresentationOfNumber + " is equal to zero");
    }
    else if (comparisonResult === CPOrderedDescending)
    {
        console.log("\tCappuccino thinks " + stringRepresentationOfNumber + " is greater thank zero");
    }
}

@end


/*!
 * This function has been taken from CPDecimal.j and had some logging added to try and work out what's going on.
 */
function CPDecimalCompare(leftOperand, rightOperand)
{
    if (leftOperand._isNaN && rightOperand._isNaN)
        return CPOrderedSame;

    if (leftOperand._isNegative != rightOperand._isNegative)
    {
        if (rightOperand._isNegative)
            return CPOrderedDescending;
        else
            return CPOrderedAscending;
    }

    // Before comparing number size check if zero (dont use CPDecimalIsZero as it is more computationally intensive)
    var leftIsZero = (leftOperand._mantissa.length == 1 && leftOperand._mantissa[0] == 0),
        rightIsZero = (rightOperand._mantissa.length == 1 && rightOperand._mantissa[0] == 0),
        // Sign is the same, quick check size (length + exp)
        s1 = leftOperand._exponent + leftOperand._mantissa.length,
        s2 = rightOperand._exponent + rightOperand._mantissa.length;



    /*!
     * The problem *seems* to be that s1 < s2 for numbers >= 0 and < 1, and rightOperand._isNegative is (correctly) false
     * This means
     */
    if (leftIsZero || s1 < s2)
    {
        if (debugCPDecimalCompare)
        {
            console.log("leftOperand:", CPDecimalString(leftOperand, nil));
            console.log("rightOperand:", CPDecimalString(rightOperand, nil));
            console.log("leftIsZero:", leftIsZero ? "true" : "false");
            console.log("rightIsZero:", rightIsZero ? "true" : "false");
            console.log("s1 < s2:", s1 < s2 ? "true" : "false");
            console.log("leftOperand._exponent:", leftOperand._exponent);
            console.log("leftOperand._mantissa.length:", leftOperand._mantissa.length);
            console.log("rightOperand._exponent:", rightOperand._exponent);
            console.log("rightOperand._mantissa.length:", leftOperand._mantissa.length);
        }

        if (rightOperand._isNegative)
        {
            if (debugCPDecimalCompare)
                console.log("rightOperand._isNegative: true");

            return CPOrderedDescending;
        }
        else
        {
            if (debugCPDecimalCompare)
                console.log("rightOperand._isNegative: false");

            return CPOrderedAscending;
        }
    }
    if (rightIsZero || s1 > s2)
    {
        if (debugCPDecimalCompare)
        {
            console.log("leftOperand:", CPDecimalString(leftOperand, nil));
            console.log("rightOperand:", CPDecimalString(rightOperand, nil));
            console.log("leftIsZero:", leftIsZero ? "true" : "false");
            console.log("rightIsZero:", rightIsZero ? "true" : "false");
            console.log("s1 < s2:", s1 < s2 ? "true" : "false");
            console.log("leftOperand._exponent:", leftOperand._exponent);
            console.log("leftOperand._mantissa.length:", leftOperand._mantissa.length);
            console.log("rightOperand._exponent:", rightOperand._exponent);
            console.log("rightOperand._mantissa.length:", leftOperand._mantissa.length);
        }

        if (debugCPDecimalCompare)
            console.log("rightIsZero");

        if (rightOperand._isNegative)
        {
            if (debugCPDecimalCompare)
                console.log("rightOperand._isNegative: true");

            return CPOrderedAscending;
        }
        else
        {
            if (debugCPDecimalCompare)
                console.log("rightOperand._isNegative: false");

            return CPOrderedDescending;
        }
    }

    // Same size, so check mantissa
    var l = MIN(leftOperand._mantissa.length, rightOperand._mantissa.length),
        i = 0;

    for (; i < l; i++)
    {
        var d = rightOperand._mantissa[i] - leftOperand._mantissa[i];

        if (d > 0)
        {
            if (rightOperand._isNegative)
                return CPOrderedDescending;
            else
                return CPOrderedAscending;
        }
        if (d < 0)
        {
            if (rightOperand._isNegative)
                return CPOrderedAscending;
            else
                return CPOrderedDescending;
        }
    }

    // Same digits, check length
    if (leftOperand._mantissa.length > rightOperand._mantissa.length)
    {
        if (rightOperand._isNegative)
            return CPOrderedAscending;
        else
            return CPOrderedDescending;
    }
    if (leftOperand._mantissa.length < rightOperand._mantissa.length)
    {
        if (rightOperand._isNegative)
            return CPOrderedDescending;
        else
            return CPOrderedAscending;
    }

    return CPOrderedSame;
}