rust/src/libstd/base64.rs

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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
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//! Base64 binary-to-text encoding
use core::iter;
use core::str;
use core::vec;
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pub trait ToBase64 {
fn to_base64(&self) -> ~str;
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}
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static CHARS: [char, ..64] = [
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
];
impl<'self> ToBase64 for &'self [u8] {
fn to_base64(&self) -> ~str {
let mut s = ~"";
unsafe {
let len = self.len();
str::reserve(&mut s, ((len + 3u) / 4u) * 3u);
let mut i = 0u;
while i < len - (len % 3u) {
let n = (self[i] as uint) << 16u |
(self[i + 1u] as uint) << 8u |
(self[i + 2u] as uint);
// This 24-bit number gets separated into four 6-bit numbers.
str::push_char(&mut s, CHARS[(n >> 18u) & 63u]);
str::push_char(&mut s, CHARS[(n >> 12u) & 63u]);
str::push_char(&mut s, CHARS[(n >> 6u) & 63u]);
str::push_char(&mut s, CHARS[n & 63u]);
i += 3u;
}
// Heh, would be cool if we knew this was exhaustive
// (the dream of bounded integer types)
match len % 3 {
0 => (),
1 => {
let n = (self[i] as uint) << 16u;
str::push_char(&mut s, CHARS[(n >> 18u) & 63u]);
str::push_char(&mut s, CHARS[(n >> 12u) & 63u]);
str::push_char(&mut s, '=');
str::push_char(&mut s, '=');
}
2 => {
let n = (self[i] as uint) << 16u |
(self[i + 1u] as uint) << 8u;
str::push_char(&mut s, CHARS[(n >> 18u) & 63u]);
str::push_char(&mut s, CHARS[(n >> 12u) & 63u]);
str::push_char(&mut s, CHARS[(n >> 6u) & 63u]);
str::push_char(&mut s, '=');
}
_ => fail!(~"Algebra is broken, please alert the math police")
}
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}
s
}
}
impl<'self> ToBase64 for &'self str {
fn to_base64(&self) -> ~str {
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str::to_bytes(*self).to_base64()
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}
}
pub trait FromBase64 {
fn from_base64(&self) -> ~[u8];
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}
impl FromBase64 for ~[u8] {
fn from_base64(&self) -> ~[u8] {
if self.len() % 4u != 0u { fail!(~"invalid base64 length"); }
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let len = self.len();
let mut padding = 0u;
if len != 0u {
if self[len - 1u] == '=' as u8 { padding += 1u; }
if self[len - 2u] == '=' as u8 { padding += 1u; }
}
let mut r = vec::with_capacity((len / 4u) * 3u - padding);
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unsafe {
let mut i = 0u;
while i < len {
let mut n = 0u;
for iter::repeat(4u) {
let ch = self[i] as char;
n <<= 6u;
if ch >= 'A' && ch <= 'Z' {
n |= (ch as uint) - 0x41u;
} else if ch >= 'a' && ch <= 'z' {
n |= (ch as uint) - 0x47u;
} else if ch >= '0' && ch <= '9' {
n |= (ch as uint) + 0x04u;
} else if ch == '+' {
n |= 0x3Eu;
} else if ch == '/' {
n |= 0x3Fu;
} else if ch == '=' {
match len - i {
1u => {
r.push(((n >> 16u) & 0xFFu) as u8);
r.push(((n >> 8u ) & 0xFFu) as u8);
return copy r;
}
2u => {
r.push(((n >> 10u) & 0xFFu) as u8);
return copy r;
}
_ => fail!(~"invalid base64 padding")
}
} else {
fail!(~"invalid base64 character");
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}
i += 1u;
};
r.push(((n >> 16u) & 0xFFu) as u8);
r.push(((n >> 8u ) & 0xFFu) as u8);
r.push(((n ) & 0xFFu) as u8);
}
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}
r
}
}
impl FromBase64 for ~str {
fn from_base64(&self) -> ~[u8] {
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str::to_bytes(*self).from_base64()
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}
}
#[cfg(test)]
mod tests {
use core::str;
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#[test]
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pub fn test_to_base64() {
fail_unless!((~"").to_base64() == ~"");
fail_unless!((~"f").to_base64() == ~"Zg==");
fail_unless!((~"fo").to_base64() == ~"Zm8=");
fail_unless!((~"foo").to_base64() == ~"Zm9v");
fail_unless!((~"foob").to_base64() == ~"Zm9vYg==");
fail_unless!((~"fooba").to_base64() == ~"Zm9vYmE=");
fail_unless!((~"foobar").to_base64() == ~"Zm9vYmFy");
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}
#[test]
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pub fn test_from_base64() {
fail_unless!((~"").from_base64() == str::to_bytes(~""));
fail_unless!((~"Zg==").from_base64() == str::to_bytes(~"f"));
fail_unless!((~"Zm8=").from_base64() == str::to_bytes(~"fo"));
fail_unless!((~"Zm9v").from_base64() == str::to_bytes(~"foo"));
fail_unless!((~"Zm9vYg==").from_base64() == str::to_bytes(~"foob"));
fail_unless!((~"Zm9vYmE=").from_base64() == str::to_bytes(~"fooba"));
fail_unless!((~"Zm9vYmFy").from_base64() == str::to_bytes(~"foobar"));
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}
}