Best way to count character spaces.

[Rikki Cattermole via Digitalmars-d-learn]

On 1/07/2015 6:33 a.m., Taylor Hillegeist wrote:
> So I am aware that Unicode is not simple... I have been working on a
> boxes like project http://boxes.thomasjensen.com/
>
> it basically puts a pretty border around stdin characters. like so:
>   ________________________
> /\                       \
> \_|Different all twisty a|
>    |of in maze are you,   |
>    |passages little.      |
>    |   ___________________|_
>     \_/_____________________/
>
> but I find that I need to know a bit more than the length of the string
> because of encoding differences
>
> I had a thought at one point to do this:
>
> MyString.splitlines.map!(a => a.toUTF32.length).reduce!max();
>
> Should get me the longest line.
>
> but this has a problem too because control characters might not take up
> space (backspace?).
>
> https://en.wikipedia.org/wiki/Unicode_control_characters
>
> leaving an unwanted nasty space :( or take weird amount of space \t. And
> perhaps the first isn't really something to worry about.
>
> Or should i do something like:
>
> MyString.splitLines
>          .map!(a => a
>                .map!(a => a
>                      .isGraphical)
>                .map!(a => cast(int) a?1:0)
>                .array
>                .reduce!((a,b) => a+b))
>          .reduce!max
>
> Mostly I am just curious of best practice in this situation.
>
> Both of the above fail with the input:
> "hello \n People \nP\u0008ofEARTH"
> on my command prompt at least.


Well I would personally use isWhite[0].
I would also use filter and count along with it.

So something like this:
size_t[] lengths = MyString.splitLines
.filter!isWhite
.count
.array;

Untested of course, but may give you ideas :)

[0] http://dlang.org/phobos/std_uni.html#.isWhite