make `serde` optional

Cargo.toml

@@ -25,13 +25,13 @@ unstable = []
 default = []
 
 [dev-dependencies]
+serde = "1.0"
 serde_json = "1.0"
 rand = "0.3"
 rustc-serialize = "0.3"
 
 [dependencies]
 libc = "0.2"
-serde = "1.0"
 
 [dependencies.rand]
 version = "0.3"
@@ -41,3 +41,8 @@ optional = true
 version = "0.3"
 optional = true
 
+[dependencies.serde]
+version = "1.0"
+optional = true
+
+

src/key.rs

@@ -15,10 +15,10 @@
 
 //! # Public and secret keys
 
-use std::marker;
+#[cfg(any(test, feature = "serde"))] use std::marker;
 #[cfg(any(test, feature = "rand"))] use rand::Rng;
 #[cfg(any(test, feature = "rustc-serialize"))] use serialize::{Decoder, Decodable, Encoder, Encodable};
-use serde::{Serialize, Deserialize, Serializer, Deserializer};
+#[cfg(any(test, feature = "serde"))] use serde::{Serialize, Deserialize, Serializer, Deserializer};
 
 use super::{Secp256k1, ContextFlag};
 use super::Error::{self, IncapableContext, InvalidPublicKey, InvalidSecretKey};
@@ -300,6 +300,7 @@ impl Encodable for PublicKey {
     }
 }
 
+#[cfg(any(test, feature = "serde"))]
 impl<'de> Deserialize<'de> for PublicKey {
     fn deserialize<D>(d: D) -> Result<PublicKey, D::Error>
         where D: Deserializer<'de>
@@ -360,6 +361,7 @@ impl<'de> Deserialize<'de> for PublicKey {
     }
 }
 
+#[cfg(any(test, feature = "serde"))]
 impl Serialize for PublicKey {
     fn serialize<S>(&self, s: S) -> Result<S::Ok, S::Error>
         where S: Serializer

src/lib.rs

@@ -38,12 +38,11 @@
 
 #![cfg_attr(all(test, feature = "unstable"), feature(test))]
 #[cfg(all(test, feature = "unstable"))] extern crate test;
+#[cfg(any(test, feature = "serde"))] extern crate serde;
 #[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 serde;
-
 extern crate libc;
 
 use libc::size_t;
@@ -201,6 +200,7 @@ impl Signature {
     }
 }
 
+#[cfg(any(test, feature = "serde"))]
 impl serde::Serialize for Signature {
     fn serialize<S>(&self, s: S) -> Result<S::Ok, S::Error>
         where S: serde::Serializer
@@ -210,6 +210,7 @@ impl serde::Serialize for Signature {
     }
 }
 
+#[cfg(any(test, feature = "serde"))]
 impl<'de> serde::Deserialize<'de> for Signature {
     fn deserialize<D>(d: D) -> Result<Signature, D::Error>
         where D: serde::Deserializer<'de>

src/macros.rs

@@ -146,6 +146,7 @@ macro_rules! impl_array_newtype {
             }
         }
 
+        #[cfg(any(test, feature = "serde"))]
         impl<'de> ::serde::Deserialize<'de> for $thing {
             fn deserialize<D>(d: D) -> Result<$thing, D::Error>
                 where D: ::serde::Deserializer<'de>
@@ -190,6 +191,7 @@ macro_rules! impl_array_newtype {
             }
         }
 
+        #[cfg(any(test, feature = "serde"))]
         impl ::serde::Serialize for $thing {
             fn serialize<S>(&self, s: S) -> Result<S::Ok, S::Error>
                 where S: ::serde::Serializer