diff options
author | Ryan Leckey <ryan@launchbadge.com> | 2017-06-01 23:22:04 -0700 |
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committer | Ryan Leckey <ryan@launchbadge.com> | 2017-06-01 23:22:04 -0700 |
commit | bfc44c331a77d8c341c076e72df5ed0b56fbd422 (patch) | |
tree | c757723957be6b880d1e0d8d26ae2b1c9c606ed2 /src/path | |
parent | 4357840e95f3646494ddeea4aae12425dfab2db8 (diff) |
Move things around and get some tests in place
Diffstat (limited to 'src/path')
-rw-r--r-- | src/path/mod.rs | 41 | ||||
-rw-r--r-- | src/path/parser.rs | 120 |
2 files changed, 161 insertions, 0 deletions
diff --git a/src/path/mod.rs b/src/path/mod.rs new file mode 100644 index 0000000..f889283 --- /dev/null +++ b/src/path/mod.rs @@ -0,0 +1,41 @@ +use std::str::FromStr; +use nom::ErrorKind; +use error::*; +use value::{Value, ValueKind}; + +mod parser; + +#[derive(Debug, Eq, PartialEq, Clone, Hash)] +pub enum Expression { + Identifier(String), + Child(Box<Expression>, String), + Subscript(Box<Expression>, i32), +} + +impl FromStr for Expression { + type Err = ConfigError; + + fn from_str(s: &str) -> Result<Expression> { + parser::from_str(s).map_err(|kind| ConfigError::PathParse(kind)) + } +} + +impl Expression { + pub fn get<'a>(self, root: &'a Value) -> Option<&'a Value> { + match self { + Expression::Identifier(id) => { + match root.kind { + // `x` access on a table is equivalent to: map[x] + ValueKind::Table(ref map) => map.get(&id), + + // all other variants return None + _ => None, + } + } + + _ => { + unimplemented!(); + } + } + } +} diff --git a/src/path/parser.rs b/src/path/parser.rs new file mode 100644 index 0000000..eea4343 --- /dev/null +++ b/src/path/parser.rs @@ -0,0 +1,120 @@ +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)); + +fn postfix(expr: Expression) -> Box<Fn(&[u8]) -> IResult<&[u8], Expression>> { + return 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.len() > 0 { + 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); + } +} |