Path lookups
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src/toml.rs
68
src/toml.rs
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@ -34,6 +34,35 @@
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//!
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//! [1]: https://github.com/mojombo/toml
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//! [2]: https://github.com/BurntSushi/toml-test
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//!
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//! # Lookups
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//!
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//! Sometimes it might be useful to decode/retrieve only internal
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//! nodes. You can use `lookup` to get corresponding value. Note, that
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//! it tries its best to traverse both tables and arrays. In the
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//! latter case it expects a zero-based index as a path component
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//!
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//! ```
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//! use std::from_str::FromStr;
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//!
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//! let toml = r#"
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//! [test]
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//! foo = "bar"
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//!
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//! [[values]]
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//! foo = "baz"
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//!
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//! [[values]]
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//! foo = "qux"
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//! "#;
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//! let value: toml::Value = FromStr::from_str(toml).unwrap();
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//! let test_foo = value.lookup("test.foo").unwrap();
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//! println!("test_foo is {}", test_foo);
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//! assert_eq!(test_foo.as_str().unwrap(), "bar");
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//! let foo1 = value.lookup("values.1.foo").unwrap();
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//! println!("foo1 is {}", foo1);
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//! assert_eq!(foo1.as_str().unwrap(), "qux");
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//! ```
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#![crate_type = "lib"]
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#![feature(macro_rules)]
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@ -142,6 +171,45 @@ impl Value {
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pub fn as_table<'a>(&'a self) -> Option<&'a Table> {
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match *self { Table(ref s) => Some(s), _ => None }
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}
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/// Lookups for value at specified path.
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///
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/// Uses '.' as a path separator.
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///
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/// Note: arrays have zero-based indexes.
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pub fn lookup<'a>(&'a self, path: &'a str) -> Option<&'a Value> {
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Value::lookup_path(self, path.split('.'))
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}
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// Performs actual traverse starting with value
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//
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// For arrays tries to convert key to uint and retrieve
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// corresponding element
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fn lookup_path<'a, I:Iterator<&'a str>>(value: &'a Value,
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components: I) -> Option<&'a Value>{
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let mut cur_value: &'a Value = value;
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let mut iter = components;
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for key in iter {
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match cur_value {
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&Table(ref hm) => {
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match hm.find_equiv::<'a>(&key) {
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Some(v) => cur_value = v,
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_ => return None
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}
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},
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&Array(ref v) => {
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let idx: Option<uint> = FromStr::from_str(key);
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match idx {
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Some(idx) => cur_value = v.get::<'a>(idx),
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_ => return None
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}
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},
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_ => return None
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}
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};
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Some(cur_value)
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}
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}
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impl FromStr for Value {
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