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use std::io::File;
use std::io::{BufferedReader};
pub type Program = Vec<OpCode>;
#[deriving(Show)]
pub enum OpCode {
Lshift,
Rshift,
Putc,
Getc,
Inc,
Dec,
Loop(Vec<OpCode>),
}
pub fn parse_file(filename: &str) -> Option<Program> {
let mut program: Program = vec!();
let mut loop_stack: Vec<Vec<OpCode>> = vec!();
let mut file = BufferedReader::new(File::open(&Path::new(filename)));
macro_rules! push(
($op:expr) => (
match loop_stack.pop() {
Some(mut v) => {
v.push($op);
loop_stack.push(v);
},
None => program.push($op)
}
);
)
for c in file.chars() {
match c.unwrap() {
'<' => push!(Lshift),
'>' => push!(Rshift),
'.' => push!(Putc),
',' => push!(Getc),
'+' => push!(Inc),
'-' => push!(Dec),
'[' => {
loop_stack.push(vec!());
},
']' => {
match loop_stack.pop() {
Some(code) => push!(Loop(code)),
None => panic!("Unbalanced braces"),
}
}
_ => {}
}
}
Some(program)
}