peg issue

lib.rs

#![feature(plugin)]
#![plugin(peg_syntax_ext)]

extern crate peg;

#[derive(Debug, PartialEq, PartialOrd)]
pub enum NumericConstant {
    U64(u64),
    I64(i64),
    F64(f64),
}

#[cfg(test)]
mod tests {
    use super::number;
    use super::NumericConstant::*;

    #[test]
    fn test_parse_u64s() {
        assert_eq!(Ok(U64(0xDEADBEEF)),  number::numeric_constant("0XDEADBEEF"));
        assert_eq!(Ok(U64(0o10202222)),  number::numeric_constant("010202222"));
        assert_eq!(Ok(U64(18446744073709551615)), number::numeric_constant("18446744073709551615"));
    }

    #[test]
    fn test_parse_i64s() {
        assert_eq!(Ok(I64(-0xDEADBEEF)), number::numeric_constant("-0xDEADBEEF"));
        assert_eq!(Ok(I64(-393)),        number::numeric_constant("-393"));
        assert_eq!(Ok(I64(-9223372036854775807)), number::numeric_constant("-9223372036854775807"));
    }

    #[test]
    fn test_parse_f64s() {
        assert_eq!(Ok(F64(37.33e15)),    number::numeric_constant("37.33e15"));
        assert_eq!(Ok(F64(-933.0)),      number::numeric_constant("-933.0"));
    }
}

peg! number (r#"
    use std::str::FromStr;
    use super::NumericConstant;

    /// Parse a numeric constant.
    pub numeric_constant -> NumericConstant
      = lit:(u64literal / i64literal / f64literal / #expected("numeric constant")) {
        lit
    }
    u64literal -> NumericConstant
      = header:$("0x" / "0X" / "0" / "") contents:$([a-fA-F0-9]+) {?
        match header {
            "0x" | "0X" => u64::from_str_radix(contents, 16),
            "0"         => u64::from_str_radix(contents, 8),
            ""          => u64::from_str_radix(contents, 10),
            _           => unreachable!()
        }
        .map_err(|e| "u64")
        .map(|u| NumericConstant::U64(u))
    }
    i64literal -> NumericConstant
      = "-" header:$("0x" / "0X" / "0" / "") contents:$([a-fA-F0-9]+) {?
        match header {
            "0x" | "0X" => i64::from_str_radix(contents, 16),
            "0"         => i64::from_str_radix(contents, 8),
            ""          => i64::from_str_radix(contents, 10),
            _           => unreachable!()
        }
        .map_err(|e| "i64")
        .map(|i| NumericConstant::I64(-i))
    }
    f64literal -> NumericConstant
      = val:$("-"? [0-9]* "."? [0-9]* ([eE][-+]?[0-9]+))? {?
        f64::from_str(val)
        .map_err(|e| "f64")
        .map(|f| NumericConstant::F64(f))
    }
"#);