Remove derivative dependency (#37)

* Remove derivative dependency

* Tweak doc comments

* Test hash impl

* Test variable list Hash impl

---------

Co-authored-by: Michael Sproul <michael@sigmaprime.io>

Cargo.toml

@@ -17,7 +17,6 @@ ethereum_ssz = "0.8.0"
 serde = "1.0.0"
 serde_derive = "1.0.0"
 typenum = "1.12.0"
-derivative = "2.1.1"
 smallvec = "1.8.0"
 arbitrary = { version = "1.0", features = ["derive"], optional = true }
 itertools = "0.13.0"

src/fixed_vector.rs

@@ -1,6 +1,5 @@
 use crate::tree_hash::vec_tree_hash_root;
 use crate::Error;
-use derivative::Derivative;
 use serde_derive::{Deserialize, Serialize};
 use std::marker::PhantomData;
 use std::ops::{Deref, DerefMut, Index, IndexMut};
@@ -45,14 +44,26 @@ pub use typenum;
 /// let long: FixedVector<_, typenum::U5> = FixedVector::from(base);
 /// assert_eq!(&long[..], &[1, 2, 3, 4, 0]);
 /// ```
-#[derive(Debug, Clone, Serialize, Deserialize, Derivative)]
-#[derivative(PartialEq, Eq, Hash(bound = "T: std::hash::Hash"))]
+#[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(transparent)]
 pub struct FixedVector<T, N> {
     vec: Vec<T>,
     _phantom: PhantomData<N>,
 }
 
+// Implement comparison functions even if N doesn't implement PartialEq
+impl<T: PartialEq, N> PartialEq for FixedVector<T, N> {
+    fn eq(&self, other: &Self) -> bool {
+        self.vec == other.vec
+    }
+}
+impl<T: Eq, N> Eq for FixedVector<T, N> {}
+impl<T: std::hash::Hash, N> std::hash::Hash for FixedVector<T, N> {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.vec.hash(state);
+    }
+}
+
 impl<T, N: Unsigned> FixedVector<T, N> {
     /// Returns `Ok` if the given `vec` equals the fixed length of `Self`. Otherwise returns
     /// `Err`.
@@ -347,6 +358,7 @@ impl<'a, T: arbitrary::Arbitrary<'a>, N: 'static + Unsigned> arbitrary::Arbitrar
 mod test {
     use super::*;
     use ssz::*;
+    use std::collections::HashSet;
     use tree_hash::{merkle_root, TreeHash};
     use tree_hash_derive::TreeHash;
     use typenum::*;
@@ -502,4 +514,18 @@ mod test {
             merkle_root(&repeat(a.tree_hash_root().as_slice(), 16), 0)
         );
     }
+
+    #[test]
+    fn std_hash() {
+        let x: FixedVector<u32, U16> = FixedVector::from(vec![3; 16]);
+        let y: FixedVector<u32, U16> = FixedVector::from(vec![4; 16]);
+        let mut hashset = HashSet::new();
+
+        for value in [x.clone(), y.clone()] {
+            assert!(hashset.insert(value.clone()));
+            assert!(!hashset.insert(value.clone()));
+            assert!(hashset.contains(&value));
+        }
+        assert_eq!(hashset.len(), 2);
+    }
 }

src/variable_list.rs

@@ -1,6 +1,5 @@
 use crate::tree_hash::vec_tree_hash_root;
 use crate::Error;
-use derivative::Derivative;
 use serde_derive::{Deserialize, Serialize};
 use std::marker::PhantomData;
 use std::ops::{Deref, DerefMut, Index, IndexMut};
@@ -47,14 +46,26 @@ pub use typenum;
 /// // Push a value to if it _does_ exceed the maximum.
 /// assert!(long.push(6).is_err());
 /// ```
-#[derive(Debug, Clone, Serialize, Deserialize, Derivative)]
-#[derivative(PartialEq, Eq, Hash(bound = "T: std::hash::Hash"))]
+#[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(transparent)]
 pub struct VariableList<T, N> {
     vec: Vec<T>,
     _phantom: PhantomData<N>,
 }
 
+// Implement comparison functions even if N doesn't implement PartialEq
+impl<T: PartialEq, N> PartialEq for VariableList<T, N> {
+    fn eq(&self, other: &Self) -> bool {
+        self.vec == other.vec
+    }
+}
+impl<T: Eq, N> Eq for VariableList<T, N> {}
+impl<T: std::hash::Hash, N> std::hash::Hash for VariableList<T, N> {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.vec.hash(state);
+    }
+}
+
 /// Maximum number of elements to pre-allocate in `try_from_iter`.
 ///
 /// Some variable lists have *very long* maximum lengths such that we can't actually fit them
@@ -321,6 +332,7 @@ impl<'a, T: arbitrary::Arbitrary<'a>, N: 'static + Unsigned> arbitrary::Arbitrar
 mod test {
     use super::*;
     use ssz::*;
+    use std::collections::HashSet;
     use tree_hash::{merkle_root, TreeHash};
     use tree_hash_derive::TreeHash;
     use typenum::*;
@@ -548,4 +560,18 @@ mod test {
             List::try_from_iter(wonky_iter).unwrap()
         );
     }
+
+    #[test]
+    fn std_hash() {
+        let x: VariableList<u32, U16> = VariableList::from(vec![3; 16]);
+        let y: VariableList<u32, U16> = VariableList::from(vec![4; 16]);
+        let mut hashset = HashSet::new();
+
+        for value in [x.clone(), y.clone()] {
+            assert!(hashset.insert(value.clone()));
+            assert!(!hashset.insert(value.clone()));
+            assert!(hashset.contains(&value));
+        }
+        assert_eq!(hashset.len(), 2);
+    }
 }