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use leb128;
use std::io::{self, BufRead, Write};
use std::str;
fn display(bytes: &[u8]) -> String {
let mut s = vec![];
// Base 10.
write!(&mut s, "{:?}\n", bytes).unwrap();
// Hex.
write!(&mut s, "[").unwrap();
for (i, b) in bytes.iter().enumerate() {
if i != 0 {
write!(&mut s, ", ").unwrap();
}
write!(&mut s, "{:0x}", b).unwrap();
}
writeln!(&mut s, "]").unwrap();
// Binary.
write!(&mut s, "[").unwrap();
for (i, b) in bytes.iter().enumerate() {
if i != 0 {
write!(&mut s, ", ").unwrap();
}
write!(&mut s, "{:08b}", b).unwrap();
}
writeln!(&mut s, "]").unwrap();
String::from_utf8(s).unwrap()
}
fn main() {
println!(
"
LEB128 Read-Eval-Print-Loop!
Converts numbers to signed and unsigned LEB128 and displays the results in
base-10, hex, and binary.
"
);
let mut stdin = io::BufReader::new(io::stdin());
let mut stdout = io::stdout();
let mut buf = vec![];
loop {
stdout.write_all(b"> ").expect("failed to write to stdout");
stdout.flush().expect("failed to flush stdout");
buf.clear();
let n = stdin
.read_until(b'\n', &mut buf)
.expect("failed to read line from stdin");
if n == 0 {
break;
}
let uleb = str::from_utf8(&buf)
.ok()
.and_then(|s| s.trim().parse().ok())
.and_then(|n: u64| {
let mut s = vec![];
leb128::write::unsigned(&mut s, n).ok()?;
Some(display(&s))
})
.unwrap_or_else(|| "error\n".into());
stdout
.write_all(b"# unsigned LEB128\n")
.and_then(|_| stdout.write_all(uleb.as_bytes()))
.and_then(|_| stdout.write_all(b"\n"))
.expect("failed to write to stdout");
let leb = str::from_utf8(&buf)
.ok()
.and_then(|s| s.trim().parse().ok())
.and_then(|n: i64| {
let mut s = vec![];
leb128::write::signed(&mut s, n).ok()?;
Some(display(&s))
})
.unwrap_or_else(|| "error\n".into());
stdout
.write_all(b"# signed LEB128\n")
.and_then(|_| stdout.write_all(leb.as_bytes()))
.and_then(|_| stdout.write_all(b"\n"))
.expect("failed to write to stdout");
stdout.flush().expect("failed to flush stdout");
}
}
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