Function eqlIgnoreCaseWtf8 [src]

Compares two WTF-8 strings using the equivalent functionality of RtlEqualUnicodeString (with case insensitive comparison enabled). This function can be called on any target. Assumes a and b are valid WTF-8.

Prototype

pub fn eqlIgnoreCaseWtf8(a: []const u8, b: []const u8) bool

Parameters

a: []const u8b: []const u8

Source

  pub fn eqlIgnoreCaseWtf8(a: []const u8, b: []const u8) bool {
    // A length equality check is not possible here because there are
    // some codepoints that have a different length uppercase UTF-8 representations
    // than their lowercase counterparts, e.g. U+0250 (2 bytes) <-> U+2C6F (3 bytes).
    // There are 7 such codepoints in the uppercase data used by Windows.

    var a_wtf8_it = std.unicode.Wtf8View.initUnchecked(a).iterator();
    var b_wtf8_it = std.unicode.Wtf8View.initUnchecked(b).iterator();

    // Use RtlUpcaseUnicodeChar on Windows when not in comptime to avoid including a
    // redundant copy of the uppercase data.
    const upcaseImpl = switch (builtin.os.tag) {
        .windows => if (@inComptime()) nls.upcaseW else ntdll.RtlUpcaseUnicodeChar,
        else => nls.upcaseW,
    };

    while (true) {
        const a_cp = a_wtf8_it.nextCodepoint() orelse break;
        const b_cp = b_wtf8_it.nextCodepoint() orelse return false;

        if (a_cp <= std.math.maxInt(u16) and b_cp <= std.math.maxInt(u16)) {
            if (a_cp != b_cp and upcaseImpl(@intCast(a_cp)) != upcaseImpl(@intCast(b_cp))) {
                return false;
            }
        } else if (a_cp != b_cp) {
            return false;
        }
    }
    // Make sure there are no leftover codepoints in b
    if (b_wtf8_it.nextCodepoint() != null) return false;

    return true;
}  