[swift-corelibs-dev] NSRegularExpression.firstMatchInString() fails on Linux

[Tony Parker]

Hi Mamatha,

> On Mar 8, 2016, at 4:15 AM, Mamatha Busi <mamabusi at in.ibm.com> wrote:
> 
>  @Philippe Hausler, @Tony Parker: Thank you for the response. 
> 
> As per Tony's suggestions I have translated CF's kCFNotFound into an NSNotFound of Foundation in 'NSTextCheckingResult'  (the place where the ranges are being constructed). Below is the code snippet with the changes:
> 
>  _regularExpression = regularExpression
>         super.init()
>         let notFound = NSRange(location: NSNotFound,length: 0)
>         for i in 0..<count {
>             ranges[i].location == kCFNotFound ? _ranges.append(notFound) : _ranges.append(ranges[i])
>         }
> 
> @Philippe: Request your comments on the above code changes.
> 
> TestFoundation has been run and I see no failures with the above changes.
> 
> The tests 'test_complexRegularExpressions' in the  TestNSRegularExpression were excluded till date. I am now running the excluded tests as well and there are a few test-cases here which deal with the ranges having NSNotFound. Along with these should there be more tests written to test the same? 
> 

Sure, more tests are always a bonus.

Please open a PR on swift-corelibs-foundatation when you’re ready to get a review.

Thanks for tackling this!
- Tony

> Regards
> Mamatha
> Mamatha Busi		
> <Mail Attachment.gif>
> Java L3 Support	
> IBM Software Group	 
> India Software Labs	 	
>  	
>  	
> e-mail:	mamabusi at in.ibm.com	 	
> Java Technology India Group <http://bit.ly/a7KpQj>	 	
> 
> 
> 
> 
> 
> 
> From:        Philippe Hausler <phausler at apple.com>
> To:        Tony Parker <anthony.parker at apple.com>
> Cc:        Mamatha Busi/India/IBM at IBMIN, swift-corelibs-dev at swift.org
> Date:        03/04/2016 12:02 AM
> Subject:        Re: [swift-corelibs-dev] NSRegularExpression.firstMatchInString() fails        on Linux
> Sent by:        phausler at apple.com
> 
> 
> 
> 
> On Mar 3, 2016, at 10:22 AM, Tony Parker via swift-corelibs-dev <swift-corelibs-dev at swift.org <mailto:swift-corelibs-dev at swift.org>> wrote:
> 
> Hi Mamatha,
> 
> On Mar 2, 2016, at 3:57 AM, Mamatha Busi via swift-corelibs-dev <swift-corelibs-dev at swift.org <mailto:swift-corelibs-dev at swift.org>> wrote:
> 
> Hello
> 
> The following test case, that currently fails on Linux,  is extracted from some of the excluded tests inside TestFoundation/TestNSRegularExpression. 
> 
> import Foundation
> 
> let searchStr = "123"
> let testRegex = try NSRegularExpression.init(pattern: "a(b|c|d)(x|y|z)*|123", options: [])
> let firstMatch = testRegex.firstMatchInString(searchStr, options: [], range: NSMakeRange(0,3))
> 
> if NSEqualRanges((firstMatch!.rangeAtIndex(1), NSMakeRange(NSNotFound,0)) {
>    print("Test passed")
> } else {
>    print("First match first capture range = \(NSStringFromRange(firstMatch!.rangeAtIndex(1)))")
>    print("Test failed")
> }
> 
> 
> 
> In the above scenario, no capture group participates in the match. So, firstMatch.rangeAtIndex(1) should ideally return range {NSNotFound, 0} but the actual returned value is range {-1, 0}. Hence the failure.
> 
> Debugging on the CoreFoundation, it is observed that the value -1 is coming from 'kCFNotFound' which is defined as -1. On the Foundation side, 'NSNotFound' is defined with the value of ‘Int.max’ (which must be Int32.max and Int64.max on 32 and 64 bit platforms respectively).
> 
> There are a couple of queries that I have:
> 
> -> Is 'NSNotFound' in Foundation mapped  to 'kCFNotFound'  in CoreFoundation?
> 
> -> If so, then why do 'NSNotFound' and 'kCFNotFound' have different values on the Foundation and CoreFoundation respectively?
> 
> 
> They don’t have the same value; we translate it manually in most places.
> 
> Also, I tested by modifying the 'kCFNotFound' value in CoreFoundation/Base.subproj/CFBase.h  (See below code snippet):
> 
> #if TARGET_RT_64_BIT
> static const CFIndex kCFNotFound = LONG_MAX;
> #else
> static const CFIndex kCFNotFound = INT_MAX;
> #endif
> 
> 
> With this change the above mentioned test-case passes but a lot of other TestFoundation tests seem to fail.
> 
> Please provide your comments on the appropriate change that is needed here. 
> 
> Thank you.
> 
> I think we probably just need to check the result from the CF function and translate it into an NSNotFound in this one particular case.
> 
> I think the problem in this case is that we fetch a buffer of CFRanges and pass that to the result creation.
> 
> ranges: UnsafeMutablePointer<CFRange>
> ...
> let result = NSTextCheckingResult.regularExpressionCheckingResultWithRanges(NSRangePointer(ranges), count: count, regularExpression: matcher.regex)
> 
> 
> Thanks,
> - Tony
> 
> 
> Regards
> Mamatha
> Mamatha Busi		
> <Mail Attachment.gif>
> Java L3 Support	
> IBM Software Group	 
> India Software Labs	 	
>  	
>  	
> e-mail:	mamabusi at in.ibm.com <mailto:mamabusi at in.ibm.com>	 	
> Java Technology India Group <http://bit.ly/a7KpQj>	 	
> 
> 
> 
> 
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