Function utf8ByteSequenceLength [src]

Given the first byte of a UTF-8 codepoint, returns a number 1-4 indicating the total length of the codepoint in bytes. If this byte does not match the form of a UTF-8 start byte, returns Utf8InvalidStartByte.

Prototype

pub fn utf8ByteSequenceLength(first_byte: u8) !u3

Parameters

first_byte: u8

Source

  pub fn utf8ByteSequenceLength(first_byte: u8) !u3 {
    // The switch is optimized much better than a "smart" approach using @clz
    return switch (first_byte) {
        0b0000_0000...0b0111_1111 => 1,
        0b1100_0000...0b1101_1111 => 2,
        0b1110_0000...0b1110_1111 => 3,
        0b1111_0000...0b1111_0111 => 4,
        else => error.Utf8InvalidStartByte,
    };
}  