Function sentinel [src]

Given a type which can have a sentinel e.g. [:0]u8, returns the sentinel value, or null if there is not one. Types which cannot possibly have a sentinel will be a compile error. Result is always comptime-known.

Prototype

pub inline fn sentinel(comptime T: type) ?Elem(T)

Parameters

T: type

Example

 test sentinel {
    try testSentinel();
    try comptime testSentinel();
}

Source

  pub inline fn sentinel(comptime T: type) ?Elem(T) {
    switch (@typeInfo(T)) {
        .array => |info| return info.sentinel(),
        .pointer => |info| {
            switch (info.size) {
                .many, .slice => return info.sentinel(),
                .one => switch (@typeInfo(info.child)) {
                    .array => |array_info| return array_info.sentinel(),
                    else => {},
                },
                else => {},
            }
        },
        else => {},
    }
    @compileError("type '" ++ @typeName(T) ++ "' cannot possibly have a sentinel");
}  