regex format string problem

[Rikki Cattermole via Digitalmars-d-learn]

On 23/11/15 9:22 PM, yawniek wrote:
> Hi Rikki,
>
> On Monday, 23 November 2015 at 03:57:06 UTC, Rikki Cattermole wrote:
>> I take it that browscap[0] does it not do what you want?
>> I have an generator at [1].
>> Feel free to steal.
>
> This looks interesting, thanks for the hint. However it might be a bit
> limited,
> i have 15M+ different User Agents with all kind of weird cases,
> sometimes not even the extensive ua-core regexs work. (if you're
> interested for testing let me know)
>
>> Also once you do get yours working, you'll want to use ctRegex and
>> generate a file with all of them in it. That'll increase performance
>> significantly.
>
> that was my plan.
>
>> Reguarding regex, if you want a named sub part use:
>> (?<text>[a-z]*)
>> Where [a-z]* is just an example.
>>
>> I would recommend you learning how input ranges work. They are used
>> with how to get the matches out, e.g.
>>
>> auto rgx = ctRegex!`([a-z])[123]`;
>> foreach(match; rgx.matchAll("b3")) {
>>     writeln(match.hit);
>> }
>
> i'm aware how this works, the problem is a different  one:
>
> i do have a second string that contains $n's which can occur in any order.
> now of course i can just go and write another regex and replace it, job
> done.
> but from looking at std.regex this seems to be built in, i just failed
> to get it to work properly, see my gist. i hoped this to be a 1liner.

So like this?

import std.regex;
import std.stdio : readln, writeln, write, stdout;

auto REG = ctRegex!(`(\S+)(?: (.*))?`);

void main() {
         for(;;) {
                 write("> ");
                 stdout.flush;
                 string line = readln();
                 line.length--;

                 if (line.length == 0)
                         return;

                 writeln("< ", line.replaceAll(REG, "Unknown program: $1"));
         }
}