[phobos] phobos commit, revision 1566

[Andrei Alexandrescu]

Actually I was looking in the wrong place. The problem is this constructor:

	1214        this(R input, size_t maxAvailable)
  	1215	    {
  	1216	        static if (backByBack)
  	1217	        {
  	1218	            while (input.length > maxAvailable)
  	1219	                input.popBack;
  	1220	        }
  	1221	        _input = input;
  	1222	        _maxAvailable = maxAvailable;
  	1223	    }

This constructor is O(n), which is unacceptable. The whole backByBack 
logic must be erased.


Andrei

On 05/29/2010 08:44 AM, dsource.org wrote:
> phobos commit, revision 1566
>
>
> user: rsinfu
>
> msg:
> Fixed bugzilla 3876: std.range.Take back/popBack methods don't work correctly.
> Thanks to Philippe Sigaud for the proposed solution.  It was helpful.
>
> The former implementation simply used input.back for Take.back.  It didn't work if input.length was larger than maxAvailable.  For example:
>    input = [ 1, 2, 3, 4, 5 ]
>    s = take(input, 3)            // [ 1, 2, 3 ]
>    s.back == input.back == 5     // wrong!
>
> Take must pop all the excess elements from the input ([4,5] in the above example) to provide correct back element.  This change makes it to do so if input is purely bidirectional.  (random access is used instead if possible.)
>
> - Added Take.opSlice
> - Added some enforcement error messages
>
> http://www.dsource.org/projects/phobos/changeset/1566
>
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