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| -rw-r--r-- | src/toml.rs | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/src/toml.rs b/src/toml.rs index 33be0f8..a4d6d03 100644 --- a/src/toml.rs +++ b/src/toml.rs @@ -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 { |