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

[roger riggs]

Hi  Claes,

The descriptions of the new methods should take the same form as
the coresponding existing methods.  The rationalization about intermediary
objects is not useful in describing the behavior of the method and 
should be omitted.

/**
  * Parses the string argument starting at fromIndex as a signed integer 
in the radix
  * specified by the second argument.
...

     static int parseInt(CharSequence s, int radix, int fromIndex)

The terminology used in java.lang.String for offsets and indexes into 
strings would
be provide a consistent base for talking about substrings.

Thanks, Roger


For example,


On 6/15/2014 6:22 PM, Claes Redestad wrote:
> I've updated the patch to use CharSequence in favor of String for all 
> new methods, as well as ensuring all new methods are package private 
> (for now):
>
> http://cr.openjdk.java.net/~redestad/8041972/webrev.2/
>
> Reviews appreciated!
>
> /Claes
>
> On 2014-06-15 14:29, Claes Redestad wrote:
>>
>> On 2014-06-15 13:48, Remi Forax wrote:
>>>
>>> On 06/15/2014 12:36 AM, Claes Redestad wrote:
>>>> Hi,
>>>>
>>>> please review this patch to add offset based variants of 
>>>> Integer.parseInt/parseUnsignedInt, Long.parseLong/parseUnsignedLong 
>>>> and expose them through JavaLangAccess along with 
>>>> formatUnsignedInt/-Long. This is proposed to enable a number of 
>>>> minor optimizations, starting with 
>>>> https://bugs.openjdk.java.net/browse/JDK-8006627
>>>>
>>>> Webrev: http://cr.openjdk.java.net/~redestad/8041972/webrev.0/
>>>>
>>>> Thanks!
>>>>
>>>> /Claes
>>>
>>> In my opinion, and as suggested in the description of 8041972, these 
>>> methods should be public.
>> Ultimately, yes. The ulterior motive here is to be able to backport 
>> these to 8u40 (maybe even 7) for internal JDK use, while updating to 
>> public (and dropping the SharedSecrets) should be done in a later, 
>> 9-only update. Adding public methods would require CCC approval, more 
>> detailed javadocs and possibly be part of a JEP, so pushing a 
>> back-portable internal patch as a first step seems reasonable.
>>> Having written my share of scanners/parsers in Java, these methods 
>>> are really helpful but
>>> given that they only rely on charAt/length of String, I think they 
>>> should take a CharSequence and not a String as first parameter,
>>> in order to support other storages of characters like by example a 
>>> java.nio.CharBuffer.
>>>
>>> So for me, instead of adding a bunch of method in shared secrets, 
>>> those method should be public and take a CharSequence.
>> I wouldn't mind switching over to CharSequence for the newly added 
>> methods. I wasn't around last time[1] this was proposed for the 
>> existing methods, but I know there were arguments that changing to a 
>> (possibly) mutable input type might have problematic side effects 
>> that would form a valid argument against this switch, while I 
>> personally share the opinion that it's up to the caller to enforce 
>> immutability when necessary and that text parsing methods should all 
>> use CharSequence when possible.
>>>
>>> Miinor nits, Integer.parseInt(String,int,int) don't need to test if 
>>> s is null given it delegated to parseInt(String, int, int, int),
>>> and Integer.parseInt(String) should directly call parseInt(s, 10, 0, 
>>> s.length()) instead of calling parseInt(s, 10) that calls
>>> parseInt(s, 10, 0) that calls parseInt(s, 10, 0, s.length()).
>>>
>>> cheers,
>>> Rémi
>> Not checking for null in parseInt(String, int, int) would mean we 
>> would get a NPE calling s.length() in the call to parseInt(String, 
>> int, int, int), so this is needed for compatibility. Microbenchmarks 
>> suggests the extra check does not have any performance impact since 
>> the JIT can easily prove that the inner null checks can be removed 
>> when an outer method.
>>
>> Calling parseInt(s, 10, 0, s.length()) directly in place of 
>> parseInt(s, 10, 0) would likewise require an earlier null check 
>> (slightly more code duplication) while being performance neutral 
>> either way.
>>
>> /Claes
>>
>> [1] 
>> https://www.mail-archive.com/core-libs-dev@openjdk.java.net/msg09694.html
>