pub struct Shebang<'a> { pub interpreter: &'a str, pub argument: Option<&'a str>, } impl<'a> Shebang<'a> { pub fn new(text: &'a str) -> Option> { if !text.starts_with("#!") { return None; } let mut pieces = text[2..] .lines() .nth(0) .unwrap_or("") .trim() .splitn(2, |c| c == ' ' || c == '\t'); let interpreter = pieces.next().unwrap_or(""); let argument = pieces.next(); if interpreter == "" { return None; } Some(Shebang { interpreter, argument, }) } } #[cfg(test)] mod test { use super::Shebang; #[test] fn split_shebang() { fn check(text: &str, expected_split: Option<(&str, Option<&str>)>) { let shebang = Shebang::new(text); assert_eq!( shebang.map(|shebang| (shebang.interpreter, shebang.argument)), expected_split ); } check("#! ", None); check("#!", None); check("#!/bin/bash", Some(("/bin/bash", None))); check("#!/bin/bash ", Some(("/bin/bash", None))); check( "#!/usr/bin/env python", Some(("/usr/bin/env", Some("python"))), ); check( "#!/usr/bin/env python ", Some(("/usr/bin/env", Some("python"))), ); check( "#!/usr/bin/env python -x", Some(("/usr/bin/env", Some("python -x"))), ); check( "#!/usr/bin/env python -x", Some(("/usr/bin/env", Some("python -x"))), ); check( "#!/usr/bin/env python \t-x\t", Some(("/usr/bin/env", Some("python \t-x"))), ); check("#/usr/bin/env python \t-x\t", None); check("#! /bin/bash", Some(("/bin/bash", None))); check("#!\t\t/bin/bash ", Some(("/bin/bash", None))); check( "#! \t\t/usr/bin/env python", Some(("/usr/bin/env", Some("python"))), ); check( "#! /usr/bin/env python ", Some(("/usr/bin/env", Some("python"))), ); check( "#! /usr/bin/env python -x", Some(("/usr/bin/env", Some("python -x"))), ); check( "#! /usr/bin/env python -x", Some(("/usr/bin/env", Some("python -x"))), ); check( "#! /usr/bin/env python \t-x\t", Some(("/usr/bin/env", Some("python \t-x"))), ); check("# /usr/bin/env python \t-x\t", None); } }