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use super::{CharSeq, ParserResult, Parser, Succ};
use regex::Regex;

pub struct Re {
    pattern: Regex
}

#[allow(unused_variables)]
pub fn re(p: &str) -> Re {
    match Regex::new(p) {
        Ok(r) => return Re{pattern: r},
        Err(e) => panic!("{}", p)
    }
}

impl Parser<String> for Re {
    fn _parse(&self, cs: &mut CharSeq) -> ParserResult<String> {
        match self.pattern.find(cs.view()) {
            Some((a, b)) => {
                if a != 0 {
                    return cs.fail(self.pattern.as_str());
                }
                let r = cs.view()[..b].to_string();
                cs.pos += b;
                return Succ(r);
            },
            None => return cs.fail(self.pattern.as_str())
        }
    }
}

#[cfg(test)]
#[allow(unused_variables)]
#[allow(unused_imports)]
mod tests {
    use super::re;
    use super::super::{CharSeq, ParserResult, Parser, Succ, Fail, Error};

    #[test]
    fn test_re1() {
        let mut cs = CharSeq::new("int x = 10;", "");
        let ident = re("[a-zA-Z_][a-zA-Z0-9_]*");
        let num = re("[1-9][0-9]*");
        let r = cs.accept(&ident).and_then(|t|
                  cs.accept(&" ").and_then(|a|
                  cs.accept(&ident).and_then(|v|
                  cs.accept(&" = ").and_then(|a|
                  cs.accept(&num).map(|n| {
                      return vec!(t.clone(), v.clone(), n.clone());
                }))))
            );
        match r {
            Succ(c) => {
                assert_eq!(c[0].as_slice(), "int");
                assert_eq!(c[1].as_slice(), "x");
                assert_eq!(c[2].as_slice(), "10");
            },
            _ => assert!(false, "bug")
        }
    }


}