std.container.dlist

import std.algorithm.comparison : equal;
import std.container : DList;

auto s = DList!int(1, 2, 3);
assert(equal(s[], [1, 2, 3]));

s.removeFront();
assert(equal(s[], [2, 3]));
s.removeBack();
assert(equal(s[], [2]));

s.insertFront([4, 5]);
assert(equal(s[], [4, 5, 2]));
s.insertBack([6, 7]);
assert(equal(s[], [4, 5, 2, 6, 7]));

// If you want to apply range operations, simply slice it.
import std.algorithm.searching : countUntil;
import std.range : popFrontN, popBackN, walkLength;

auto sl = DList!int([1, 2, 3, 4, 5]);
assert(countUntil(sl[], 2) == 1);

auto r = sl[];
popFrontN(r, 2);
popBackN(r, 2);
assert(r.equal([3]));
assert(walkLength(r) == 1);

// DList.Range can be used to remove elements from the list it spans
auto nl = DList!int([1, 2, 3, 4, 5]);
for (auto rn = nl[]; !rn.empty;)
    if (rn.front % 2 == 0)
        nl.popFirstOf(rn);
    else
        rn.popFront();
assert(equal(nl[], [1, 3, 5]));
auto rs = nl[];
rs.popFront();
nl.remove(rs);
assert(equal(nl[], [1]));