one step towards unification of std.algorithm and std.string

[Andrei Alexandrescu]

Simen kjaeraas wrote:
> On Wed, 30 Dec 2009 19:45:02 +0100, Andrei Alexandrescu 
> <SeeWebsiteForEmail at erdani.org> wrote:
> 
>> I've wanted for a long time to move more stuff from std.string into 
>> std.algorithm. One issue that has kept me from doing that is the case 
>> issue, i.e. some string functions have mind/ignore case flavors that 
>> don't make sense for other data types. For example consider cmp() and 
>> icmp(): http://www.digitalmars.com/d/2.0/phobos/std_string.html#cmp or 
>> the recently changed indexOf: 
>> http://www.digitalmars.com/d/2.0/phobos/std_string.html#indexOf
>>
>> It occurred to me that I can transfer the case sensitivity away from 
>> the algorithm into the data. To do so, we only need to define one more 
>> data type NoCase that behaves much like a dchar but defines opEquals 
>> to compare ignoring case. Then, we need to define a NoCase range that 
>> behaves like a bidirectional range of dchar but again uses 
>> case-insensitive comparisons. Add some garnishing and you get to write:
>>
>> string a = "Hello, World!"
>> auto x = indexOf(a, nocase("world"));
>> assert(x == 7);
>>
>> I'm quite excited about this because it modularizes the entire case 
>> business, opens strings to many algorithms, and allows generalization 
>> of string algorithms.
>>
>> Well, that is until I hit 
>> http://d.puremagic.com/issues/show_bug.cgi?id=3659
>>
>> Any thoughts and ideas would be appreciated.
>>
>>
>> Andrei
> 
> Sound nice. I've also wanted to see the two combined.
> I take it the NoCase range is a lazy wrapper of a (d|w)?char range?

I think there will be a NoCase character type that can be compared to 
dchar, and a NoCase range type that wraps any other range that traffics 
in dchar.

> Some testing shows that 3659 can be sidestepped by making opEquals a
> template function, or by creating more than one opEquals, where one
> matches const bool( const ref typeof( this ) ).

Thanks a lot Simen, that's a lifesaver.


Andrei