| use std::collections::HashMap; |
| 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) |
| // _s |
| .chain(0x5F..0x60) |
| .collect(); |
| print_encode_table(&url_alphabet, "URL_SAFE_ENCODE", 0); |
| print_decode_table(&url_alphabet, "URL_SAFE_DECODE", 0); |
| } |
| |
| fn print_encode_table(alphabet: &[u8], const_name: &str, indent_depth: usize) { |
| println!("#[cfg_attr(rustfmt, rustfmt_skip)]"); |
| println!( |
| "{:width$}pub const {}: &'static [u8; 64] = &[", |
| "", |
| const_name, |
| width = indent_depth |
| ); |
| |
| for (i, b) in alphabet.iter().enumerate() { |
| println!( |
| "{:width$}{}, // input {} (0x{:X}) => '{}' (0x{:X})", |
| "", |
| b, |
| i, |
| i, |
| String::from_utf8(vec![*b as u8]).unwrap(), |
| b, |
| width = indent_depth + 4 |
| ); |
| } |
| |
| println!("{:width$}];", "", width = indent_depth); |
| } |
| |
| fn print_decode_table(alphabet: &[u8], const_name: &str, indent_depth: usize) { |
| // map of alphabet bytes to 6-bit morsels |
| let mut input_to_morsel = HashMap::<u8, u8>::new(); |
| |
| // standard base64 alphabet bytes, in order |
| for (morsel, ascii_byte) in alphabet.iter().enumerate() { |
| // truncation cast is fine here |
| let _ = input_to_morsel.insert(*ascii_byte, morsel as u8); |
| } |
| |
| println!("#[cfg_attr(rustfmt, rustfmt_skip)]"); |
| println!( |
| "{:width$}pub const {}: &'static [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); |
| } |