1const B64_ENCODE: [u8; 64] = [
2 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50,
3 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66,
4 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76,
5 0x77, 0x78, 0x79, 0x7a, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x2b, 0x2f,
6];
7
8const B64_PAD: u8 = 0x3d;
9
10pub struct B64<T>(T);
11
12pub trait B64Encode<I, O> {
13 fn encode(input: I) -> O;
14}
15
16impl B64Encode<&[u8], String> for B64<String> {
17 fn encode(input: &[u8]) -> String {
18 let bytes = input;
19 let length = bytes.len();
20 let mut vec = Vec::<u8>::with_capacity(length * 4 / 3);
21 let mut index = 0;
22 if length >= 3 {
23 while index <= (length - 3) {
24 let value = (bytes[index] as u32) << 16
25 | (bytes[index + 1] as u32) << 8
26 | (bytes[index + 2] as u32);
27 vec.push(B64_ENCODE[((value >> 18) & 0b11_1111) as usize]);
28 vec.push(B64_ENCODE[((value >> 12) & 0b11_1111) as usize]);
29 vec.push(B64_ENCODE[((value >> 6) & 0b11_1111) as usize]);
30 vec.push(B64_ENCODE[(value & 0b11_1111) as usize]);
31 index += 3;
32 }
33 }
34 match length - index {
35 2 => {
36 let value = (bytes[index] as u32) << 16 | (bytes[index + 1] as u32) << 8;
37 vec.push(B64_ENCODE[((value >> 18) & 0b11_1111) as usize]);
38 vec.push(B64_ENCODE[((value >> 12) & 0b11_1111) as usize]);
39 vec.push(B64_ENCODE[((value >> 6) & 0b11_1111) as usize]);
40 vec.push(B64_PAD);
41 }
42 1 => {
43 let value = (bytes[index] as u32) << 16;
44 vec.push(B64_ENCODE[((value >> 18) & 0b11_1111) as usize]);
45 vec.push(B64_ENCODE[((value >> 12) & 0b11_1111) as usize]);
46 vec.push(B64_PAD);
47 vec.push(B64_PAD);
48 }
49 _ => {}
50 };
51 String::from_utf8(vec).unwrap()
52 }
53}