RFR [9] 8041972: Add improved parse/format methods for Long/Integer

[Claes Redestad]

Thank you for looking at this, Mike!

  New webrev: http://cr.openjdk.java.net/~redestad/8041972/webrev.12

On 2014-07-12 00:55, Mike Duigou wrote:
> Some comments:
>
> - The NumberFormatException.forInputString for some CharSequence is probably misleading since it doesn't consider the begin-end range which was in effect for the parsing. Rather than extracting the substring just for the error message perhaps include the index at which the error occurred. ie. add a NumberFormatException.forCharSequence(s, idx) static method

I think not extracting the actual substring for error messages will 
quickly become awkward for cases where the sequence is representing 
something really large and/or noisy, so I think it's safer to only 
output the subsequence being parsed. In line with your other 
suggestions, I've added a forCharSequence which takes the sequence, 
beginIndex, endIndex and the index at which the error was generated to 
produce NFEs with messages in the style of 'Error at index 5 in: "-1234S"'

>
> - Long.java: Why not throw new NumberFormatException("Empty input") or call throw NumberFormatException.forInputString("");
Fixed!
>
> - declaration of and assignment to multmin could be combined. declaration of "result" could also be moved later.
Fixed. I did the same for digit and narrowed the scoping of these vars.
>
> - Since it's not part of the public API I recommend moving the System/JavaLangAccess changes to a separate RFE. (and it needs a test).
I've broken out those changes and will file a separate RFE for the 
formatUnsigned additions to JLS. Do you think we need to drop the 
"/format" from the name of this RFE?

Thanks!

/Claes
>
>
> On Jun 27 2014, at 12:02 , Claes Redestad <claes.redestad at oracle.com> wrote:
>
>> Hi,
>>
>> updated webrev:http://cr.openjdk.java.net/~redestad/8041972/webrev.11
>>
>> Changes:
>> - Remove use of IllegalArgumentException in favor of IndexOutOfBoundsException/NumberFormatException, making the new methods behave in line with how String.substring wouldat some edge cases: "100".substring(3)equals "", thus Integer.parseInt("100", 10, 3) now throw NumberFormatException, while Integer.parseInt("100", 10, 4)/"100".substring(4) will throw IOOB.
>> - For performance reasons the old and new methodshave been split apart. This introduces some code duplication, but removes the need to add special checks in some places.
>> - Added more tests
>>
>> /Claes
>>
>> On 06/27/2014 10:54 AM, Paul Sandoz wrote:
>>> On Jun 26, 2014, at 6:53 PM, Claes Redestad <claes.redestad at oracle.com> wrote:
>>>
>>>> On 06/25/2014 06:43 PM, Paul Sandoz wrote:
>>>>> On Jun 19, 2014, at 7:39 PM, Claes Redestad <claes.redestad at oracle.com> wrote:
>>>>>> Hi,
>>>>>>
>>>>>> an updated webrev with reworked, public methods is available here:
>>>>>> http://cr.openjdk.java.net/~redestad/8041972/webrev.8/
>>>>>>
>>>>>> Reviews are yet again appreciated!
>>>>>>
>>>>> I think "if (s == null)" or "Objects.requireNonNull(s)" is preferable to s.getClass(). (I am informed by those more knowledgeable than i that the latter also has poorer performance in the client compiler.)
>>>> Agreed. Using s.getClass() was necessitated to retain performance using default compiler (-XX:+TieredCompilation) in the microbenchmarks I've been using, and going back to testing with C1 (via means of -XX:TieredStartAtLevel=1-3), it's apparent that the patch can cause a regression with the client compiler that I hadn't checked.It even looks like C2 alone (-XX:-TieredCompilation) suffers slightly.
>>>>
>>>> Changing to Objects.requireNonNull doesn't seem to make things better, though. Rather the regression seem to be due to C1 (and in some ways even C2) not dealing very well with the increased degrees of freedoms in the new methods, so I'm currently considering splitting apart the implementations to keep the old implementations of parseX(String[, int]) untouched while duplicating some code to build the new methods. Ugly, but I guess it's anecessary evil here.
>>>>
>>> Ok.  Perhaps it might be possible to place the specifics of constraint checking in public methods, but they defer to a general private method that can assume it's arguments are safe (or such arguments are checked by other method calls e.g. CS.charAt)
>>>
>>>
>>>>> Related to the above, it might be preferable to retain the existing semantics of throwing NumberFormatException on a null string value, since someone might switch between parseInt(String ) and parseInt(String, int, int, int) and the null will then slip through the catch of NumberFormatException.
>>>> Consider Integer.parseInt(s.substring(1)) and Integer.parseInt(s, 10, 1): the first would throw NullPointerException currently if s == null, while the latter instead would start throwing NumberFormatException. I think we should favor throwing a NPE here. I'd argue that the risk that someone changes to any of the range-based alternatives when they aren't replacing a call to substring or similar are slim to none.
>>>>
>>> A good point.
>>>
>>>
>>>>> You could just use IndexOutOfBoundsException for the case of beginIndex < 0 and beginIndex >= endIndex and endIndex > s.length(), as is similarly the case for String.substring. Again, like previously, switching between parseInt(String, int, int) parseInt(String, int, int, int) requires no additional catching. You might want to add a comment in the code that some IndexOutOfBoundsException exceptions are implicit via calls to s.charAt (i did a double take before realizing :-) ).
>>>> Fair points. I could argue String.substring(int, int), StringBuilder.append(CharSequence, int, int)etc are wrong, but I guess that might be a losing battle. :-)
>>>>
>>> Right, if we were starting again it might be different but i think consistency is important.
>>>
>>>
>>>>> Integer.requireNonEmpty could be a static package private method on String (or perhaps even static public, it seems useful), plus i would not bother with the static import in this case.
>>>> The requireNonEmpty throws NumberFormatException to keep compatibility with the old methods, so it wouldn't make much sense to add that to String.
>>> Doh! what was i thinking. If it stays perhaps place it as a package private method on Number.
>>>
>>>
>>>> If I split the parseX(String... and parseX(CharSequence... implementations as I intend to, this method will be redundant though.
>>>>
>>> Ok.
>>>
>>> Paul.