Path lookups

This commit is contained in:
Valerii Hiora 2014-06-25 12:22:11 +03:00
parent b663d6ae99
commit dd828e613b

View file

@ -34,6 +34,35 @@
//!
//! [1]: https://github.com/mojombo/toml
//! [2]: https://github.com/BurntSushi/toml-test
//!
//! # Lookups
//!
//! Sometimes it might be useful to decode/retrieve only internal
//! nodes. You can use `lookup` to get corresponding value. Note, that
//! it tries its best to traverse both tables and arrays. In the
//! latter case it expects a zero-based index as a path component
//!
//! ```
//! use std::from_str::FromStr;
//!
//! let toml = r#"
//! [test]
//! foo = "bar"
//!
//! [[values]]
//! foo = "baz"
//!
//! [[values]]
//! foo = "qux"
//! "#;
//! let value: toml::Value = FromStr::from_str(toml).unwrap();
//! let test_foo = value.lookup("test.foo").unwrap();
//! println!("test_foo is {}", test_foo);
//! assert_eq!(test_foo.as_str().unwrap(), "bar");
//! let foo1 = value.lookup("values.1.foo").unwrap();
//! println!("foo1 is {}", foo1);
//! assert_eq!(foo1.as_str().unwrap(), "qux");
//! ```
#![crate_type = "lib"]
#![feature(macro_rules)]
@ -142,6 +171,45 @@ impl Value {
pub fn as_table<'a>(&'a self) -> Option<&'a Table> {
match *self { Table(ref s) => Some(s), _ => None }
}
/// Lookups for value at specified path.
///
/// Uses '.' as a path separator.
///
/// Note: arrays have zero-based indexes.
pub fn lookup<'a>(&'a self, path: &'a str) -> Option<&'a Value> {
Value::lookup_path(self, path.split('.'))
}
// Performs actual traverse starting with value
//
// For arrays tries to convert key to uint and retrieve
// corresponding element
fn lookup_path<'a, I:Iterator<&'a str>>(value: &'a Value,
components: I) -> Option<&'a Value>{
let mut cur_value: &'a Value = value;
let mut iter = components;
for key in iter {
match cur_value {
&Table(ref hm) => {
match hm.find_equiv::<'a>(&key) {
Some(v) => cur_value = v,
_ => return None
}
},
&Array(ref v) => {
let idx: Option<uint> = FromStr::from_str(key);
match idx {
Some(idx) => cur_value = v.get::<'a>(idx),
_ => return None
}
},
_ => return None
}
};
Some(cur_value)
}
}
impl FromStr for Value {