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use std::collections::{HashMap, HashSet};
use std::iter::Iterator;
fn main() {
println!("pub const INVALID_VALUE: u8 = 255;");
// A-Z
let standard_alphabet: Vec<u8> = (0x41..0x5B)
// a-z
.chain(0x61..0x7B)
// 0-9
.chain(0x30..0x3A)
// +
.chain(0x2B..0x2C)
// /
.chain(0x2F..0x30)
.collect();
print_encode_table(&standard_alphabet, "STANDARD_ENCODE", 0);
print_decode_table(&standard_alphabet, "STANDARD_DECODE", 0);
// A-Z
let url_alphabet: Vec<u8> = (0x41..0x5B)
// a-z
.chain(0x61..0x7B)
// 0-9
.chain(0x30..0x3A)
// -
.chain(0x2D..0x2E)
// _
.chain(0x5F..0x60)
.collect();
print_encode_table(&url_alphabet, "URL_SAFE_ENCODE", 0);
print_decode_table(&url_alphabet, "URL_SAFE_DECODE", 0);
// ./0123456789
let crypt_alphabet: Vec<u8> = (b'.'..(b'9' + 1))
// A-Z
.chain(b'A'..(b'Z' + 1))
// a-z
.chain(b'a'..(b'z' + 1))
.collect();
print_encode_table(&crypt_alphabet, "CRYPT_ENCODE", 0);
print_decode_table(&crypt_alphabet, "CRYPT_DECODE", 0);
// ./
let bcrypt_alphabet: Vec<u8> = (b'.'..(b'/' + 1))
// A-Z
.chain(b'A'..(b'Z' + 1))
// a-z
.chain(b'a'..(b'z' + 1))
// 0-9
.chain(b'0'..(b'9' + 1))
.collect();
print_encode_table(&bcrypt_alphabet, "BCRYPT_ENCODE", 0);
print_decode_table(&bcrypt_alphabet, "BCRYPT_DECODE", 0);
// A-Z
let imap_alphabet: Vec<u8> = (0x41..0x5B)
// a-z
.chain(0x61..0x7B)
// 0-9
.chain(0x30..0x3A)
// +
.chain(0x2B..0x2C)
// ,
.chain(0x2C..0x2D)
.collect();
print_encode_table(&imap_alphabet, "IMAP_MUTF7_ENCODE", 0);
print_decode_table(&imap_alphabet, "IMAP_MUTF7_DECODE", 0);
// '!' - '-'
let binhex_alphabet: Vec<u8> = (0x21..0x2E)
// 0-9
.chain(0x30..0x3A)
// @-N
.chain(0x40..0x4F)
// P-V
.chain(0x50..0x57)
// X-[
.chain(0x58..0x5C)
// `-f
.chain(0x60..0x66)
// h-m
.chain(0x68..0x6E)
// p-r
.chain(0x70..0x73)
.collect();
print_encode_table(&binhex_alphabet, "BINHEX_ENCODE", 0);
print_decode_table(&binhex_alphabet, "BINHEX_DECODE", 0);
}
fn print_encode_table(alphabet: &[u8], const_name: &str, indent_depth: usize) {
check_alphabet(alphabet);
println!("#[rustfmt::skip]");
println!(
"{:width$}pub const {}: &[u8; 64] = &[",
"",
const_name,
width = indent_depth
);
for (i, b) in alphabet.iter().enumerate() {
println!(
"{:width$}{}, // input {} (0x{:X}) => '{}' (0x{:X})",
"",
b,
i,
i,
String::from_utf8(vec![*b as u8]).unwrap(),
b,
width = indent_depth + 4
);
}
println!("{:width$}];", "", width = indent_depth);
}
fn print_decode_table(alphabet: &[u8], const_name: &str, indent_depth: usize) {
check_alphabet(alphabet);
// map of alphabet bytes to 6-bit morsels
let mut input_to_morsel = HashMap::<u8, u8>::new();
// standard base64 alphabet bytes, in order
for (morsel, ascii_byte) in alphabet.iter().enumerate() {
// truncation cast is fine here
let _ = input_to_morsel.insert(*ascii_byte, morsel as u8);
}
println!("#[rustfmt::skip]");
println!(
"{:width$}pub const {}: &[u8; 256] = &[",
"",
const_name,
width = indent_depth
);
for ascii_byte in 0..256 {
let (value, comment) = match input_to_morsel.get(&(ascii_byte as u8)) {
None => (
"INVALID_VALUE".to_string(),
format!("input {} (0x{:X})", ascii_byte, ascii_byte),
),
Some(v) => (
format!("{}", *v),
format!(
"input {} (0x{:X} char '{}') => {} (0x{:X})",
ascii_byte,
ascii_byte,
String::from_utf8(vec![ascii_byte as u8]).unwrap(),
*v,
*v
),
),
};
println!(
"{:width$}{}, // {}",
"",
value,
comment,
width = indent_depth + 4
);
}
println!("{:width$}];", "", width = indent_depth);
}
fn check_alphabet(alphabet: &[u8]) {
// ensure all characters are distinct
assert_eq!(64, alphabet.len());
let mut set: HashSet<u8> = HashSet::new();
set.extend(alphabet);
assert_eq!(64, set.len());
// must be ASCII to be valid as single UTF-8 bytes
for &b in alphabet {
assert!(b <= 0x7F_u8);
// = is assumed to be padding, so cannot be used as a symbol
assert_ne!(b'=', b);
}
}
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