diff --git a/lib/std/sort.zig b/lib/std/sort.zig index f8b8a3913..0fb029bb5 100644 --- a/lib/std/sort.zig +++ b/lib/std/sort.zig @@ -1210,3 +1210,41 @@ pub fn max(comptime T: type, items: []T, lessThan: fn (lhs: T, rhs: T) bool) T { } return biggest; } + +pub fn isSorted(comptime T: type, items: []const T, lessThan: fn (lhs: T, rhs: T) bool) bool { + var i: usize = 1; + while (i < items.len) : (i += 1) { + if (lessThan(items[i], items[i - 1])) { + return false; + } + } + + return true; +} + +test "std.sort.isSorted" { + testing.expect(isSorted(i32, &[_]i32{}, asc(i32))); + testing.expect(isSorted(i32, &[_]i32{10}, asc(i32))); + testing.expect(isSorted(i32, &[_]i32{ 1, 2, 3, 4, 5 }, asc(i32))); + testing.expect(isSorted(i32, &[_]i32{ -10, 1, 1, 1, 10 }, asc(i32))); + + testing.expect(isSorted(i32, &[_]i32{}, desc(i32))); + testing.expect(isSorted(i32, &[_]i32{-20}, desc(i32))); + testing.expect(isSorted(i32, &[_]i32{ 3, 2, 1, 0, -1 }, desc(i32))); + testing.expect(isSorted(i32, &[_]i32{ 10, -10 }, desc(i32))); + + testing.expect(isSorted(i32, &[_]i32{ 1, 1, 1, 1, 1 }, asc(i32))); + testing.expect(isSorted(i32, &[_]i32{ 1, 1, 1, 1, 1 }, desc(i32))); + + testing.expectEqual(false, isSorted(i32, &[_]i32{ 5, 4, 3, 2, 1 }, asc(i32))); + testing.expectEqual(false, isSorted(i32, &[_]i32{ 1, 2, 3, 4, 5 }, desc(i32))); + + testing.expect(isSorted(u8, "abcd", asc(u8))); + testing.expect(isSorted(u8, "zyxw", desc(u8))); + + testing.expectEqual(false, isSorted(u8, "abcd", desc(u8))); + testing.expectEqual(false, isSorted(u8, "zyxw", asc(u8))); + + testing.expect(isSorted(u8, "ffff", asc(u8))); + testing.expect(isSorted(u8, "ffff", desc(u8))); +}