[Issue 19238] New: no-arg splitter should work on ranges of characters

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19238

          Issue ID: 19238
           Summary: no-arg splitter should work on ranges of characters
           Product: D
           Version: D2
          Hardware: x86
                OS: Mac OS X
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: phobos
          Assignee: nobody at puremagic.com
          Reporter: schveiguy at yahoo.com

Currently, std.algorithm.iteration.splitter has an overload that works just
with character arrays and takes no parameters. This special overload is
different from the other versions of splitter in that:

1. it only works with *arrays* of characters
2. the inferred separator is any run of whitespace, as opposed to the other
splitter overloads where the separator is a fixed length.

It's currently impossible to use the other overloads of splitter to mimic this
behavior with a non-array range, such as byCodeUnit.

However, there's nothing inherently special about character arrays that makes
it incorrect to use on arbitrary code unit ranges.

In other words, this should compile:

auto range = "hello    world".byCodeUnit.splitter;
static assert(is(typeof(range.front()) == typeof("hello".byCodeUnit()));
assert(range.equals(["hello".byCodeUnit, "world".byCodeUnit]);

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