Natural sorted list of files

[Dmitry via Digitalmars-d-learn]

On Monday, 6 February 2017 at 17:35:02 UTC, Jonathan M Davis 
wrote:
> You have to import std.range to use groupBy.
Of course, "import std.range" already done.

I tested it also with full rosetta's code:

import std.stdio, std.string, std.algorithm, std.array, std.conv, 
std.ascii, std.range;

string[] naturalSort(string[] arr) /*pure @safe*/ {
     static struct Part {
         string s;

         int opCmp(in ref Part other) const pure {
             return (s[0].isDigit && other.s[0].isDigit) ?
                    cmp([s.to!ulong], [other.s.to!ulong]) :
                    cmp(s, other.s);
         }
     }

     static mapper(in string txt) /*pure nothrow @safe*/ {
         auto r = txt
                  .strip
                  .tr(whitespace, " ", "s")
                  .toLower
                  .groupBy!isDigit
                  .map!(p => Part(p.text))
                  .array;
         return (r.length > 1 && r[0].s == "the") ? r.dropOne : r;
     }

     return arr.schwartzSort!mapper.release;
}

void main() /*@safe*/ {
     auto tests = [
     // Ignoring leading spaces.
     ["ignore leading spaces: 2-2", " ignore leading spaces: 2-1", 
"
      ignore leading spaces: 2+1", "  ignore leading spaces: 2+0"],

     // Ignoring multiple adjacent spaces (m.a.s).
     ["ignore m.a.s spaces: 2-2", "ignore m.a.s  spaces: 2-1",
      "ignore m.a.s   spaces: 2+0", "ignore m.a.s    spaces: 2+1"],

     // Equivalent whitespace characters.
     ["Equiv. spaces: 3-3", "Equiv.\rspaces: 3-2",
      "Equiv.\x0cspaces: 3-1", "Equiv.\x0bspaces: 3+0",
      "Equiv.\nspaces: 3+1", "Equiv.\tspaces: 3+2"],

     // Case Indepenent sort.
     ["cASE INDEPENENT: 3-2", "caSE INDEPENENT: 3-1",
      "casE INDEPENENT: 3+0", "case INDEPENENT: 3+1"],

     // Numeric fields as numerics.
     ["foo100bar99baz0.txt", "foo100bar10baz0.txt",
      "foo1000bar99baz10.txt", "foo1000bar99baz9.txt"],

     // Title sorts.
     ["The Wind in the Willows", "The 40th step more",
      "The 39 steps", "Wanda"]];

     foreach (test; tests)
         writeln(test, "\n", test.naturalSort, "\n");
}

result:
$ dub
Performing "debug" build using dmd for x86_64.
sort_test ~master: building configuration "application"...
source/app.d(19,18): Error: no property 'groupBy' for type 
'string'
dmd failed with exit code 1.