[Issue 4114] New: Support static arrays in some algorithms

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=4114

           Summary: Support static arrays in some algorithms
           Product: D
           Version: future
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: patch
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody at puremagic.com
        ReportedBy: bearophile_hugs at eml.cc


--- Comment #0 from bearophile_hugs at eml.cc 2010-04-21 15:53:45 PDT ---
Fixed-sized stack-allocated static arrays can't support all features of a
dynamic array, so they are not a fully flexible range. So it's not possible to
perform some operations/algorithms on static arrays.

But there are several basic operations that I might desire to perform on static
arrays too, like to test if their items are sorted (isSorted), to sort them
(sort()), or to compare the items of a sequence to the items of a static array
(equals).

Currently std.algorithm.isSorted doesn't work with static arrays, but I see no
point in forbidding isSorted() or sort() on a static array. A simple workaround
is to use:
isSorted(stat_arr[])
sort(stat_arr[])
to give isSorted a dynamic array view of the same contents of the static array.
This is not too much bad looking, but it gratuitously breaks some generic code.


This shows a possible simple way to fix it: to rename the current isSorted as
isSorted_impl, and add this function template that uses isSorted_impl:


import std.algorithm: isSorted_impl = isSorted;

bool isSorted(alias less="a < b", Range)(Range data)
    if (__traits(isStaticArray, Range) || isForwardRange!Range) {
        static if (__traits(isStaticArray, Range))
            return isSorted_impl!(less)(data[]);
        else
            return isSorted_impl!(less)(data);
}

void main() {
    int[3] b = [1, 2, 3];
    assert(isSorted(b));
}


Better, the original isSorted() can become a function statically nested in this
wrapper.

std.range.array, equal() and sort() can be augmented in similar ways.

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