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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.as_bytes()).to_result().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!();
}
}
}
}
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