source code
// The Computer Language Benchmarks Game
// http://benchmarksgame.alioth.debian.org/
//
// contributed by the Rust Project Developers
// contributed by TeXitoi
use std::cmp::min;
use std::io;
const LINE_LENGTH: usize = 60;
const IM: u32 = 139968;
struct MyRandom {
last: u32
}
impl MyRandom {
fn new() -> MyRandom { MyRandom { last: 42 } }
fn normalize(p: f32) -> u32 {(p * IM as f32).floor() as u32}
fn gen(&mut self) -> u32 {
self.last = (self.last * 3877 + 29573) % IM;
self.last
}
}
struct AAGen<'a> {
rng: &'a mut MyRandom,
data: Vec<(u32, u8)>
}
impl<'a> AAGen<'a> {
fn new<'b>(rng: &'b mut MyRandom, aa: &[(char, f32)]) -> AAGen<'b> {
let mut cum = 0.;
let data = aa.iter()
.map(|&(ch, p)| { cum += p; (MyRandom::normalize(cum), ch as u8) })
.collect();
AAGen { rng: rng, data: data }
}
}
impl<'a> Iterator for AAGen<'a> {
type Item = u8;
fn next(&mut self) -> Option<u8> {
let r = self.rng.gen();
self.data.iter()
.skip_while(|pc| pc.0 < r)
.map(|&(_, c)| c)
.next()
}
}
fn make_fasta<W: io::Write, I: Iterator<Item=u8>>(
wr: &mut W, header: &str, mut it: I, mut n: usize)
-> io::Result<()>
{
try!(wr.write_all(header.as_bytes()));
let mut line = [0u8; LINE_LENGTH + 1];
while n > 0 {
let nb = min(LINE_LENGTH, n);
for i in (0..nb) {
line[i] = it.next().unwrap();
}
n -= nb;
line[nb] = '\n' as u8;
try!(wr.write_all(&line[..(nb+1)]));
}
Ok(())
}
fn run<W: io::Write>(writer: &mut W) -> io::Result<()> {
let n = std::env::args_os().nth(1)
.and_then(|s| s.into_string().ok())
.and_then(|n| n.parse().ok())
.unwrap_or(1000);
let rng = &mut MyRandom::new();
let alu =
"GGCCGGGCGCGGTGGCTCACGCCTGTAATCCCAGCACTTTGG\
GAGGCCGAGGCGGGCGGATCACCTGAGGTCAGGAGTTCGAGA\
CCAGCCTGGCCAACATGGTGAAACCCCGTCTCTACTAAAAAT\
ACAAAAATTAGCCGGGCGTGGTGGCGCGCGCCTGTAATCCCA\
GCTACTCGGGAGGCTGAGGCAGGAGAATCGCTTGAACCCGGG\
AGGCGGAGGTTGCAGTGAGCCGAGATCGCGCCACTGCACTCC\
AGCCTGGGCGACAGAGCGAGACTCCGTCTCAAAAA";
let iub = &[('a', 0.27), ('c', 0.12), ('g', 0.12),
('t', 0.27), ('B', 0.02), ('D', 0.02),
('H', 0.02), ('K', 0.02), ('M', 0.02),
('N', 0.02), ('R', 0.02), ('S', 0.02),
('V', 0.02), ('W', 0.02), ('Y', 0.02)];
let homosapiens = &[('a', 0.3029549426680),
('c', 0.1979883004921),
('g', 0.1975473066391),
('t', 0.3015094502008)];
try!(make_fasta(writer, ">ONE Homo sapiens alu\n",
alu.as_bytes().iter().cycle().map(|c| *c), n * 2));
try!(make_fasta(writer, ">TWO IUB ambiguity codes\n",
AAGen::new(rng, iub), n * 3));
try!(make_fasta(writer, ">THREE Homo sapiens frequency\n",
AAGen::new(rng, homosapiens), n * 5));
writer.flush()
}
fn main() {
run(&mut io::stdout()).unwrap()
}