feature: add conditional support for serde

src/merkle/mmr/accumulator.rs

@@ -4,6 +4,7 @@ use super::{
 };
 
 #[derive(Debug, Clone, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct MmrPeaks {
     /// The number of leaves is used to differentiate accumulators that have the same number of
     /// peaks. This happens because the number of peaks goes up-and-down as the structure is used

src/merkle/mmr/full.rs

@@ -29,6 +29,7 @@ use std::error::Error;
 /// Since this is a full representation of the MMR, elements are never removed and the MMR will
 /// grow roughly `O(2n)` in number of leaf elements.
 #[derive(Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct Mmr {
     /// Refer to the `forest` method documentation for details of the semantics of this value.
     pub(super) forest: usize,

src/merkle/mmr/proof.rs

@@ -3,6 +3,7 @@ use super::super::MerklePath;
 use super::full::{high_bitmask, leaf_to_corresponding_tree};
 
 #[derive(Debug, Clone, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct MmrProof {
     /// The state of the MMR when the MmrProof was created.
     pub forest: usize,