Re: Path as an object in std.path

[Lars T. Kyllingstad]

On Thursday, 6 June 2013 at 17:28:56 UTC, Steven Schveighoffer 
wrote:
On Thu, 06 Jun 2013 13:25:56 -0400, Lars T. Kyllingstad 
<pub...@kyllingen.net> wrote:

On Thursday, 6 June 2013 at 17:13:10 UTC, Steven Schveighoffer 
wrote:
On Thu, 06 Jun 2013 12:14:30 -0400, Dylan Knutson 
<tcdknut...@gmail.com> wrote:

It doesn't do any allocations that the user won't have to do 
anyways. Paths have to be normalized before comparison; not 
doing so isn't correct behavior. Eg, the strings `foo../bar` 
!= `bar`, yet they're equivalent paths. Path encapsulates 
the behavior. So it's the difference between

buildNormalizedPath(s1) == buildNormalizedPath(s2);

and

p1 == p2;

This can be done without allocations.

I know.  There are a few additions that I've been planning to 
make for std.path for the longest time, I just haven't found 
the time to do so yet.  Specifically, I want to add a couple 
of functions that deal with ranges of path segments rather 
than full path strings.

The first one is a lazy "path normaliser":

  assert (equal(pathNormalizer(["foo", "bar", "..", "baz"]),
                ["foo", "bar", "baz"]));

With this, non-allocating path comparison is easy.  The 
verbose version of p1 == p2, which could be wrapped for 
convenience, is then:

  equal(pathNormalizer(pathSplitter(p1)),
        pathNormalizer(pathSplitter(p2)))

You can also use filenameCmp() as a predicate to equal() to 
make the comparison case-insensitive on OSes where this is 
expected.  Very general and composable, and easily wrappable.

Great!  I'd highly suggest pathEqual which takes two ranges of 
dchar and does the composition and OS-specific comparison for 
you.

They don't have to be dchar if all the building blocks are 
templates (as the existing ones are):

bool pathEqual(CaseSensitive cs = CaseSensitive.osDefault, C1, C2)
              (const(C1)[] p1, const(C2)[] p2)
    if (isSomeChar!C1 && isSomeChar!C2)
{
    return equal!((a, b) => filenameCharCmp!cs(a, b) == 0)
                 (pathNormalizer(pathSplitter(p1)),
                  pathNormalizer(pathSplitter(p2)));
}