Source
pub fn calcUtf16LeLenImpl(utf8: []const u8, comptime surrogates: Surrogates) !usize {
const utf8DecodeImpl = switch (surrogates) {
.cannot_encode_surrogate_half => utf8Decode,
.can_encode_surrogate_half => wtf8Decode,
};
var src_i: usize = 0;
var dest_len: usize = 0;
while (src_i < utf8.len) {
const n = try utf8ByteSequenceLength(utf8[src_i]);
const next_src_i = src_i + n;
const codepoint = try utf8DecodeImpl(utf8[src_i..next_src_i]);
if (codepoint < 0x10000) {
dest_len += 1;
} else {
dest_len += 2;
}
src_i = next_src_i;
}
return dest_len;
}