make `rustc-serialize` crate optional

Cargo.toml

@@ -27,13 +27,17 @@ default = []
 [dev-dependencies]
 serde_json = "1.0"
 rand = "0.3"
+rustc-serialize = "0.3"
 
 [dependencies]
 libc = "0.2"
-rustc-serialize = "0.3"
 serde = "1.0"
 
 [dependencies.rand]
 version = "0.3"
 optional = true
 
+[dependencies.rustc-serialize]
+version = "0.3"
+optional = true
+

src/key.rs

@@ -17,7 +17,7 @@
 
 use std::marker;
 #[cfg(any(test, feature = "rand"))] use rand::Rng;
-use serialize::{Decoder, Decodable, Encoder, Encodable};
+#[cfg(any(test, feature = "rustc-serialize"))] use serialize::{Decoder, Decodable, Encoder, Encodable};
 use serde::{Serialize, Deserialize, Serializer, Deserializer};
 
 use super::{Secp256k1, ContextFlag};
@@ -254,6 +254,7 @@ impl PublicKey {
     }
 }
 
+#[cfg(any(test, feature = "rustc-serialize"))]
 impl Decodable for PublicKey {
     fn decode<D: Decoder>(d: &mut D) -> Result<PublicKey, D::Error> {
         d.read_seq(|d, len| {
@@ -292,6 +293,7 @@ impl From<ffi::PublicKey> for PublicKey {
 }
 
 
+#[cfg(any(test, feature = "rustc-serialize"))]
 impl Encodable for PublicKey {
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
         self.serialize().encode(s)

src/lib.rs

@@ -40,8 +40,8 @@
 #[cfg(all(test, feature = "unstable"))] extern crate test;
 #[cfg(test)] extern crate serde_json as json;
 #[cfg(any(test, feature = "rand"))] extern crate rand;
+#[cfg(any(test, feature = "rustc-serialize"))] extern crate rustc_serialize as serialize;
 
-extern crate rustc_serialize as serialize;
 extern crate serde;
 
 extern crate libc;

src/macros.rs

@@ -116,6 +116,7 @@ macro_rules! impl_array_newtype {
             }
         }
 
+        #[cfg(any(test, feature = "rustc-serialize"))]
         impl ::serialize::Decodable for $thing {
             fn decode<D: ::serialize::Decoder>(d: &mut D) -> Result<$thing, D::Error> {
                 use serialize::Decodable;
@@ -137,6 +138,7 @@ macro_rules! impl_array_newtype {
             }
         }
 
+        #[cfg(any(test, feature = "rustc-serialize"))]
         impl ::serialize::Encodable for $thing {
             fn encode<S: ::serialize::Encoder>(&self, s: &mut S)
                                                -> Result<(), S::Error> {