proposition to std.range: SortedRange.indexOf(value)

[Andrei Alexandrescu]

On 12/19/12 11:45 AM, Alexander Tankeev wrote:
> On 12/19/2012 08:19 PM, Andrei Alexandrescu wrote:
>
>>> I find very useful and clean interface that provides SortedRange, but it
>>> was disappointing that it have binarySearch to answer does it
>>> .contains(value), but can't return the .indexOf(value). In my opinion it
>>> should be part of the interface.
>
>> What to return if there are several indexes for a value? That's why the
>> more general lowerBound, upperBound, equalRange, and trisect are defined.
>
> Ok, and what if value isn't in Range at all? How lowerBound, upperBound,
> equalRange can help in such case?
>
> auto a = assumeSorted([ 0, 1, 2, 3, 4, 5, 10, 11, 12, 14 ]);
> auto p = a.lowerBound(7);
> assert(equal(p, [0, 1, 2, 3, 4, 5]))

Take the length of the lower bound and compare it against the length of 
the sorted range.

auto firstIndex = p.length;
if (firstIndex < a.length) { ... found ... }

> Sure I can do .contains(value) and then index is
> .lowerBound(value).length but it's 2 searches where 1 could be enough.
>
> And what if you need all indexes of equal elements? Then you should do 3
> searches where 1 could be enough.

Use trisect for that.


Andrei