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Diffstat (limited to 'src/path/parser.rs')
-rw-r--r-- | src/path/parser.rs | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/src/path/parser.rs b/src/path/parser.rs new file mode 100644 index 0000000..ee3fb65 --- /dev/null +++ b/src/path/parser.rs @@ -0,0 +1,121 @@ +use nom::*; +use std::str::{FromStr, from_utf8}; +use super::Expression; + +named!(ident_<String>, + map!( + map_res!(is_a!( + "abcdefghijklmnopqrstuvwxyz \ + ABCDEFGHIJKLMNOPQRSTUVWXYZ \ + 0123456789 \ + _-" + ), from_utf8), + |s: &str| { + s.to_string() + } + ) +); + +named!(integer <i32>, + map_res!( + map_res!( + ws!(digit), + from_utf8 + ), + FromStr::from_str + ) +); + +named!(ident<Expression>, map!(ident_, Expression::Identifier)); + +#[allow(cyclomatic_complexity)] +fn postfix(expr: Expression) -> Box<Fn(&[u8]) -> IResult<&[u8], Expression>> { + Box::new(move |i: &[u8]| { + alt!(i, + do_parse!( + tag!(".") >> + id: ident_ >> + (Expression::Child(Box::new(expr.clone()), id)) + ) | + delimited!( + char!('['), + do_parse!( + negative: opt!(tag!("-")) >> + num: integer >> + (Expression::Subscript( + Box::new(expr.clone()), + num * (if negative.is_none() { 1 } else { -1 }) + )) + ), + char!(']') + ) + ) + }) +} + +pub fn from_str(input: &str) -> Result<Expression, ErrorKind> { + match ident(input.as_bytes()) { + IResult::Done(mut rem, mut expr) => { + while !rem.is_empty() { + match postfix(expr)(rem) { + IResult::Done(rem_, expr_) => { + rem = rem_; + expr = expr_; + } + + // Forward Incomplete and Error + result => { + return result.to_result(); + } + } + } + + Ok(expr) + } + + // Forward Incomplete and Error + result => result.to_result(), + } +} + +#[cfg(test)] +mod test { + use super::*; + use super::Expression::*; + + #[test] + fn test_id() { + let parsed: Expression = from_str("abcd").unwrap(); + assert_eq!(parsed, Identifier("abcd".into())); + } + + #[test] + fn test_id_dash() { + let parsed: Expression = from_str("abcd-efgh").unwrap(); + assert_eq!(parsed, Identifier("abcd-efgh".into())); + } + + #[test] + fn test_child() { + let parsed: Expression = from_str("abcd.efgh").unwrap(); + let expected = Child(Box::new(Identifier("abcd".into())), "efgh".into()); + + assert_eq!(parsed, expected); + } + + #[test] + fn test_subscript() { + let parsed: Expression = from_str("abcd[12]").unwrap(); + let expected = Subscript(Box::new(Identifier("abcd".into())), 12); + + assert_eq!(parsed, expected); + } + + #[test] + fn test_subscript_neg() { + let parsed: Expression = from_str("abcd[-1]").unwrap(); + let expected = Subscript(Box::new(Identifier("abcd".into())), -1); + + assert_eq!(parsed, expected); + } +} |