RFR 8015978: Incorrect transformation of XPath expression "string(-0)"

[Aleksej Efimov]

Joe,
I have added the call to '!Double.isFinite(d)', the '-0.0' to '+0.0' 
conversion still there.
new webrev: http://cr.openjdk.java.net/~coffeys/webrev.8015978.v3/ 
<http://cr.openjdk.java.net/%7Ecoffeys/webrev.8015978.v3/>

Regards,
Aleksej

On 06/10/2013 08:30 PM, Joe Darcy wrote:
> Hi Aleksej,
>
> On 6/10/2013 8:02 AM, Aleksej Efimov wrote:
>> Hi Joe,
>> We can replace the "Double.isNaN(d) || Double.isInfinite(d)" with 
>> "!Double.isFinite(d)" - I agree that this one check looks better, but 
>> we still need to do the -0.0 -> 0.0 conversion to solve the reported 
>> problem. And as I understand (might be wrong) modification of this 
>> check won't help us to achieve this goal, we still need to do the 
>> conversion:
>> +            //Convert -0.0 to +0.0 other values remains the same
>> +            d = d + 0.0;
>> +
>
> Right; changing the set of Double.isFoo methods called earlier doesn't 
> change the need for the (d + 0.0) expression. I just noticed the 
> double isFoo calls when looking at the code and saw an opportunity to 
> use the new method.
>
> Cheers,
>
> -Joe
>
>
>> Regards,
>> -Aleksej
>>
>> On 06/09/2013 10:23 PM, Joe Darcy wrote:
>>> Hello Aleksej,
>>>
>>> Looking at the code, I have another suggestion. If this code can run 
>>> exclusively on JDK 8 or later, replace
>>>
>>>  955             if (Double.isNaN(d) || Double.isInfinite(d))
>>>  956                 return(Double.toString(d));
>>>
>>> with
>>>
>>>  955             if (!Double.isFinite(d))
>>>  956                 return(Double.toString(d));
>>>
>>> Cheers,
>>>
>>> -Joe
>>>
>>> On 6/9/2013 11:18 AM, Aleksej Efimov wrote:
>>>> Joe,
>>>>
>>>> I definitely like it:
>>>> 1. Its a one-line change - perfect size.
>>>> 2. Its fastest one from discussed previously.
>>>> 3. -0.0 -> 0.0 has tests.
>>>> 4. And it solves our problem.
>>>>
>>>> As a result of all props the next version of webrev: 
>>>> http://cr.openjdk.java.net/~coffeys/webrev.8015978.v2/ 
>>>> <http://cr.openjdk.java.net/%7Ecoffeys/webrev.8015978.v2/>
>>>>
>>>> Thanks
>>>> -Aleksej
>>>>
>>>> On 06/07/2013 11:11 PM, huizhe wang wrote:
>>>>> Nice. One-line change, I guess Aleksej would love it :-)
>>>>>
>>>>> On 6/7/2013 10:19 AM, Joe Darcy wrote:
>>>>>> I'll do you one better; you can turn a negative zero into a 
>>>>>> positive zero leaving other values unchanged like this:
>>>>>>
>>>>>>     d = d + 0.0;
>>>>>>
>>>>>> In IEEE 754 under the round-to-nearest-even rounding mode 
>>>>>> required by Java
>>>>>>     -0.0 + 0.0 => (+)0.0
>>>>>>
>>>>>> This trick is used in various places in Java's numerical 
>>>>>> libraries, is required behavior by our specifications, and even 
>>>>>> has some tests for it :-)
>>>>>>
>>>>>> -Joe
>>>>>>
>>>>>> On 6/7/2013 8:43 AM, David Chase wrote:
>>>>>>> Wouldn't be more efficient to do the following, assuming that 
>>>>>>> the full Java compilation chain respects the trickiness of 0 vs -0:
>>>>>>>
>>>>>>>     if (d == 0.0) {
>>>>>>>          d=0.0 // Jam -0 == +0 to +0, per 
>>>>>>> http://www.w3.org/TR/xpath/#function-string
>>>>>>>
>>>>>>>     }
>>>>>>>
>>>>>>> Division's plenty more expensive than assigning a constant, 
>>>>>>> especially on platforms that lack hardware FP division.
>>>>>>>
>>>>>>> David
>>>>>>>
>>>>>>> On 2013-06-07, at 2:03 AM, huizhe wang <huizhe.wang at oracle.com> 
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Hi Aleksej,
>>>>>>>>
>>>>>>>> According to XPath spec, both positive and negative zero are 
>>>>>>>> converted to the string 0, so it seems doesn't matter. But if 
>>>>>>>> you want to detect the negative zero, you may do the following:
>>>>>>>>     if (d == 0.0 && 1/d < 0.0) {
>>>>>>>>          d=0.0
>>>>>>>>     }
>>>>>>>>
>>>>>>>> Recognizing that (-0.0 == 0.0), and (1/(-0.0) == -Infinity).
>>>>>>>>
>>>>>>>> -Joe
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>