Change Json methods to &str and allow Indexing

Json's find, find_path, and search methods now use &str rather
than &String.

Json can now be indexed with &str (for Objects) and uint
(for Lists).

Tests updated to reflect this change.

[breaking-change]

src/libserialize/json.rs

@@ -203,6 +203,7 @@ fn main() {
 use std::str::ScalarValue;
 use std::string;
 use std::vec::Vec;
+use std::ops;
 
 use Encodable;
 
@@ -884,9 +885,9 @@ pub fn to_pretty_str(&self) -> string::String {
 
      /// If the Json value is an Object, returns the value associated with the provided key.
     /// Otherwise, returns None.
-    pub fn find<'a>(&'a self, key: &string::String) -> Option<&'a Json>{
+    pub fn find<'a>(&'a self, key: &str) -> Option<&'a Json>{
         match self {
-            &Object(ref map) => map.find(key),
+            &Object(ref map) => map.find_with(|s| key.cmp(&s.as_slice())),
             _ => None
         }
     }
@@ -894,7 +895,7 @@ pub fn find<'a>(&'a self, key: &string::String) -> Option<&'a Json>{
     /// Attempts to get a nested Json Object for each key in `keys`.
     /// If any key is found not to exist, find_path will return None.
     /// Otherwise, it will return the Json value associated with the final key.
-    pub fn find_path<'a>(&'a self, keys: &[&string::String]) -> Option<&'a Json>{
+    pub fn find_path<'a>(&'a self, keys: &[&str]) -> Option<&'a Json>{
         let mut target = self;
         for key in keys.iter() {
             match target.find(*key) {
@@ -908,20 +909,19 @@ pub fn find_path<'a>(&'a self, keys: &[&string::String]) -> Option<&'a Json>{
     /// If the Json value is an Object, performs a depth-first search until
     /// a value associated with the provided key is found. If no value is found
     /// or the Json value is not an Object, returns None.
-    pub fn search<'a>(&'a self, key: &string::String) -> Option<&'a Json> {
+    pub fn search<'a>(&'a self, key: &str) -> Option<&'a Json> {
         match self {
             &Object(ref map) => {
-                match map.find(key) {
+                match map.find_with(|s| key.cmp(&s.as_slice())) {
                     Some(json_value) => Some(json_value),
                     None => {
-                        let mut value : Option<&'a Json> = None;
                         for (_, v) in map.iter() {
-                            value = v.search(key);
-                            if value.is_some() {
-                                break;
+                            match v.search(key) {
+                                x if x.is_some() => return x,
+                                _ => ()
                             }
                         }
-                        value
+                        None
                     }
                 }
             },
@@ -1063,6 +1063,21 @@ pub fn as_null(&self) -> Option<()> {
     }
 }
 
+impl<'a> ops::Index<&'a str, Json>  for Json {
+    fn index<'a>(&'a self, idx: & &str) -> &'a Json {
+        self.find(*idx).unwrap()
+    }
+}
+
+impl ops::Index<uint, Json> for Json {
+    fn index<'a>(&'a self, idx: &uint) -> &'a Json {
+        match self {
+            &List(ref v) => v.index(idx),
+            _ => panic!("can only index Json with uint if it is a list")
+        }
+    }
+}
+
 /// The output of the streaming parser.
 #[deriving(PartialEq, Clone, Show)]
 pub enum JsonEvent {
@@ -3055,26 +3070,33 @@ fn test_decode_errors_enum() {
     #[test]
     fn test_find(){
         let json_value = from_str("{\"dog\" : \"cat\"}").unwrap();
-        let found_str = json_value.find(&"dog".to_string());
-        assert!(found_str.is_some() && found_str.unwrap().as_string().unwrap() == "cat");
+        let found_str = json_value.find("dog");
+        assert!(found_str.unwrap().as_string().unwrap() == "cat");
     }
 
     #[test]
     fn test_find_path(){
         let json_value = from_str("{\"dog\":{\"cat\": {\"mouse\" : \"cheese\"}}}").unwrap();
-        let found_str = json_value.find_path(&[&"dog".to_string(),
-                                             &"cat".to_string(), &"mouse".to_string()]);
-        assert!(found_str.is_some() && found_str.unwrap().as_string().unwrap() == "cheese");
+        let found_str = json_value.find_path(&["dog", "cat", "mouse"]);
+        assert!(found_str.unwrap().as_string().unwrap() == "cheese");
     }
 
     #[test]
     fn test_search(){
         let json_value = from_str("{\"dog\":{\"cat\": {\"mouse\" : \"cheese\"}}}").unwrap();
-        let found_str = json_value.search(&"mouse".to_string()).and_then(|j| j.as_string());
-        assert!(found_str.is_some());
+        let found_str = json_value.search("mouse").and_then(|j| j.as_string());
         assert!(found_str.unwrap() == "cheese");
     }
 
+    #[test]
+    fn test_index(){
+        let json_value = from_str("{\"animals\":[\"dog\",\"cat\",\"mouse\"]}").unwrap();
+        let ref list = json_value["animals"];
+        assert_eq!(list[0].as_string().unwrap(), "dog");
+        assert_eq!(list[1].as_string().unwrap(), "cat");
+        assert_eq!(list[2].as_string().unwrap(), "mouse");
+    }
+
     #[test]
     fn test_is_object(){
         let json_value = from_str("{}").unwrap();