Vector

import std.range : only;
import std.algorithm : map, equal;

static struct Foo{
    int i;
    string str;
}

Vector!(Foo, 4) vec;

assert(vec.empty);
assert(vec.capacity == 4);
assert(typeof(vec).minimalCapacity == 4);

vec.append(Foo(1, "A"));
assert(vec.length == 1);

vec.append(only(Foo(2, "B"), Foo(3, "C")));
assert(vec.length == 3);

vec.emplaceBack(4, "D");
assert(vec.length == 4);
assert(vec.capacity == 4);

vec.insert(1, Foo(5, "E"));
assert(vec.length == 5);
assert(vec.capacity > 4);
assert(equal(vec[].map!(e => e.str), only("A", "E", "B", "C", "D")));

vec.erase(vec[1 .. $-1]);   //same as vec.erase(1, 3);
assert(vec == only(Foo(1, "A"), Foo(4, "D")));


vec = Vector!(Foo, 2).build(Foo(-1, "X"), Foo(-2, "Y"));
assert(equal(vec[].map!(e => e.str), only("X", "Y")));


vec.clear();
assert(vec.length == 0);
assert(vec.capacity > 4);

vec.release();
assert(vec.length == 0);
assert(vec.capacity == typeof(vec).minimalCapacity);