calcWtf8Len

pub fn calcWtf8Len(wtf16le: []const u16) usize {
    var it = Wtf16LeIterator.init(wtf16le);
    var num_wtf8_bytes: usize = 0;
    while (it.nextCodepoint()) |codepoint| {
        // Note: If utf8CodepointSequenceLength is ever changed to error on surrogate
        // codepoints, then it would no longer be eligible to be used in this context.
        num_wtf8_bytes += utf8CodepointSequenceLength(codepoint) catch |err| switch (err) {
            error.CodepointTooLarge => unreachable,
        };
    }
    return num_wtf8_bytes;
}