Implement RFC#28: Add PartialOrd::partial_cmp

I ended up altering the semantics of Json's PartialOrd implementation.
It used to be the case that Null < Null, but I can't think of any reason
for an ordering other than the default one so I just switched it over to
using the derived implementation.

This also fixes broken `PartialOrd` implementations for `Vec` and
`TreeMap`.

RFC: 0028-partial-cmp

1 files changed, 1 insertions, 57 deletions

diff --git a/src/libserialize/json.rs b/src/libserialize/json.rs
index d8dd2938b34..9f5f020152f 100644
--- a/src/libserialize/json.rs
+++ b/src/libserialize/json.rs
@@ -244,7 +244,7 @@ use std::vec::Vec;
 use Encodable;
 
 /// Represents a json value
-#[deriving(Clone, PartialEq)]
+#[deriving(Clone, PartialEq, PartialOrd)]
 pub enum Json {
     Number(f64),
     String(String),
@@ -2087,62 +2087,6 @@ impl ::Decoder<DecoderError> for Decoder {
     }
 }
 
-/// Test if two json values are less than one another
-impl PartialOrd for Json {
-    fn lt(&self, other: &Json) -> bool {
-        match *self {
-            Number(f0) => {
-                match *other {
-                    Number(f1) => f0 < f1,
-                    String(_) | Boolean(_) | List(_) | Object(_) |
-                    Null => true
-                }
-            }
-
-            String(ref s0) => {
-                match *other {
-                    Number(_) => false,
-                    String(ref s1) => s0 < s1,
-                    Boolean(_) | List(_) | Object(_) | Null => true
-                }
-            }
-
-            Boolean(b0) => {
-                match *other {
-                    Number(_) | String(_) => false,
-                    Boolean(b1) => b0 < b1,
-                    List(_) | Object(_) | Null => true
-                }
-            }
-
-            List(ref l0) => {
-                match *other {
-                    Number(_) | String(_) | Boolean(_) => false,
-                    List(ref l1) => (*l0) < (*l1),
-                    Object(_) | Null => true
-                }
-            }
-
-            Object(ref d0) => {
-                match *other {
-                    Number(_) | String(_) | Boolean(_) | List(_) => false,
-                    Object(ref d1) => d0 < d1,
-                    Null => true
-                }
-            }
-
-            Null => {
-                match *other {
-                    Number(_) | String(_) | Boolean(_) | List(_) |
-                    Object(_) =>
-                        false,
-                    Null => true
-                }
-            }
-        }
-    }
-}
-
 /// A trait for converting values to JSON
 pub trait ToJson {
     /// Converts the value of `self` to an instance of JSON