Merge #68: Impl PartialOrd, Ord for 3 types

1e64777 Impl PartialOrd, Ord for 3 types (Riccardo Casatta)

Pull request description:

  RangeProof, SurjectionProof and PedersenCommitment

  The purpose of this is having downstream types like elements::Transaction be usable in ordered collections.

  bitcoin::Transaction already support this for the same reason

ACKs for top commit:
  apoelstra:
    ACK 1e64777

Tree-SHA512: b523ce6f85a255d9c7f8881171fb68ac9e1e21c2ae1429183a469f2fb3379f883cc756e3847c6e489a09ea4bd7fa5eaf7c493c8934c66a71dc319804b8c99847

Author: apoelstra

secp256k1-zkp-sys/src/zkp.rs

@@ -426,6 +426,26 @@ impl PartialEq for SurjectionProof {
 
 impl Eq for SurjectionProof {}
 
+impl Ord for SurjectionProof {
+    fn cmp(&self, other: &Self) -> core::cmp::Ordering {
+        match self.n_inputs.cmp(&other.n_inputs) {
+            core::cmp::Ordering::Equal => {}
+            ord => return ord,
+        }
+        match self.used_inputs.cmp(&other.used_inputs) {
+            core::cmp::Ordering::Equal => {}
+            ord => return ord,
+        }
+        self.data.cmp(&other.data)
+    }
+}
+
+impl PartialOrd for SurjectionProof {
+    fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
 impl Default for SurjectionProof {
     fn default() -> Self {
         SurjectionProof::new()
@@ -454,7 +474,7 @@ impl SurjectionProof {
 
 #[cfg(feature = "std")]
 #[repr(C)]
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct RangeProof(Box<[c_uchar]>);
 
 #[cfg(feature = "std")]
@@ -513,7 +533,7 @@ impl From<Tag> for [u8; 32] {
 
 // TODO: Replace this with ffi::PublicKey?
 #[repr(C)]
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, PartialOrd, Ord)]
 pub struct PedersenCommitment([c_uchar; 64]);
 impl_array_newtype!(PedersenCommitment, c_uchar, 64);
 impl_raw_debug!(PedersenCommitment);

src/zkp/pedersen.rs

@@ -5,7 +5,7 @@ use crate::{from_hex, Error, Generator, Secp256k1, Signing, Tweak, ZERO_TWEAK};
 use core::{fmt, slice, str};
 
 /// Represents a commitment to a single u64 value.
-#[derive(Debug, PartialEq, Clone, Copy, Eq, Hash)]
+#[derive(Debug, PartialEq, Clone, Copy, Eq, Hash, PartialOrd, Ord)]
 pub struct PedersenCommitment(ffi::PedersenCommitment);
 
 impl PedersenCommitment {

src/zkp/rangeproof.rs

@@ -13,7 +13,7 @@ use std::str;
 /// Represents a range proof.
 ///
 /// TODO: Store rangeproof info
-#[derive(Debug, PartialEq, Clone, Eq, Hash)]
+#[derive(Debug, PartialEq, Clone, Eq, Hash, PartialOrd, Ord)]
 pub struct RangeProof {
     inner: ffi::RangeProof,
 }

src/zkp/surjection_proof.rs

@@ -6,7 +6,7 @@ use core::mem::size_of;
 use std::str;
 
 /// Represents a surjection proof.
-#[derive(Debug, PartialEq, Clone, Eq, Hash)]
+#[derive(Debug, PartialEq, Clone, Eq, Hash, PartialOrd, Ord)]
 pub struct SurjectionProof {
     inner: ffi::SurjectionProof,
 }