Add tree_hash_derive crate
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parent
354f823c16
commit
2be05a466f
@ -19,6 +19,7 @@ members = [
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"eth2/utils/ssz_derive",
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"eth2/utils/swap_or_not_shuffle",
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"eth2/utils/tree_hash",
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"eth2/utils/tree_hash_derive",
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"eth2/utils/fisher_yates_shuffle",
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"eth2/utils/test_random_derive",
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"beacon_node",
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@ -12,7 +12,7 @@ pub struct BTreeOverlay {
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impl BTreeOverlay {
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pub fn new<T>(item: &T, initial_offset: usize) -> Result<Self, Error>
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where
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T: CachedTreeHashSubtree<T>,
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T: CachedTreeHashSubTree<T>,
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{
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item.btree_overlay(initial_offset)
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}
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@ -15,7 +15,7 @@ impl Into<Vec<u8>> for TreeHashCache {
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impl TreeHashCache {
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pub fn new<T>(item: &T) -> Result<Self, Error>
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where
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T: CachedTreeHashSubtree<T>,
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T: CachedTreeHashSubTree<T>,
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{
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item.new_cache()
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}
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@ -32,7 +32,7 @@ impl TreeHashCache {
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leaves_and_subtrees: Vec<Self>,
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) -> Result<Self, Error>
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where
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T: CachedTreeHashSubtree<T>,
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T: CachedTreeHashSubTree<T>,
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{
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let offset_handler = BTreeOverlay::new(item, 0)?;
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@ -4,7 +4,7 @@ use ssz::ssz_encode;
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mod vec;
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impl CachedTreeHashSubtree<u64> for u64 {
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impl CachedTreeHashSubTree<u64> for u64 {
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fn item_type() -> ItemType {
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ItemType::Basic
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}
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@ -1,8 +1,8 @@
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use super::*;
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impl<T> CachedTreeHashSubtree<Vec<T>> for Vec<T>
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impl<T> CachedTreeHashSubTree<Vec<T>> for Vec<T>
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where
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T: CachedTreeHashSubtree<T>,
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T: CachedTreeHashSubTree<T>,
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{
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fn item_type() -> ItemType {
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ItemType::List
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@ -168,7 +168,7 @@ where
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fn get_packed_leaves<T>(vec: &Vec<T>) -> Result<Vec<u8>, Error>
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where
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T: CachedTreeHashSubtree<T>,
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T: CachedTreeHashSubTree<T>,
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{
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let num_packed_bytes = (BYTES_PER_CHUNK / T::packing_factor()) * vec.len();
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let num_leaves = num_sanitized_leaves(num_packed_bytes);
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@ -35,7 +35,7 @@ pub enum ItemType {
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Composite,
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}
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pub trait CachedTreeHash<T>: CachedTreeHashSubtree<T> + Sized {
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pub trait CachedTreeHash<T>: CachedTreeHashSubTree<T> + Sized {
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fn update_internal_tree_hash_cache(self, old: T) -> Result<(Self, Self), Error>;
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fn cached_tree_hash_root(&self) -> Option<Vec<u8>>;
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@ -43,7 +43,7 @@ pub trait CachedTreeHash<T>: CachedTreeHashSubtree<T> + Sized {
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fn clone_without_tree_hash_cache(&self) -> Self;
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}
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pub trait CachedTreeHashSubtree<Item> {
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pub trait CachedTreeHashSubTree<Item> {
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fn item_type() -> ItemType;
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fn btree_overlay(&self, chunk_offset: usize) -> Result<BTreeOverlay, Error>;
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@ -63,7 +63,7 @@ fn works_when_embedded() {
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assert_eq!(&merkle[0..32], &root[..]);
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}
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impl CachedTreeHashSubtree<InternalCache> for InternalCache {
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impl CachedTreeHashSubTree<InternalCache> for InternalCache {
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fn item_type() -> ItemType {
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ItemType::Composite
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}
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@ -131,7 +131,7 @@ pub struct Inner {
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pub d: u64,
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}
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impl CachedTreeHashSubtree<Inner> for Inner {
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impl CachedTreeHashSubTree<Inner> for Inner {
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fn item_type() -> ItemType {
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ItemType::Composite
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}
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@ -203,7 +203,7 @@ pub struct Outer {
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pub c: u64,
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}
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impl CachedTreeHashSubtree<Outer> for Outer {
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impl CachedTreeHashSubTree<Outer> for Outer {
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fn item_type() -> ItemType {
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ItemType::Composite
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}
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16
eth2/utils/tree_hash_derive/Cargo.toml
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16
eth2/utils/tree_hash_derive/Cargo.toml
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@ -0,0 +1,16 @@
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[package]
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name = "tree_hash_derive"
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version = "0.1.0"
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authors = ["Paul Hauner <paul@paulhauner.com>"]
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edition = "2018"
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description = "Procedural derive macros for SSZ tree hashing."
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[lib]
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proc-macro = true
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[dev-dependencies]
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tree_hash = { path = "../tree_hash" }
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[dependencies]
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syn = "0.15"
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quote = "0.6"
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125
eth2/utils/tree_hash_derive/src/lib.rs
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125
eth2/utils/tree_hash_derive/src/lib.rs
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@ -0,0 +1,125 @@
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#![recursion_limit = "256"]
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extern crate proc_macro;
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use proc_macro::TokenStream;
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use quote::quote;
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use syn::{parse_macro_input, DeriveInput};
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/// Returns a Vec of `syn::Ident` for each named field in the struct, whilst filtering out fields
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/// that should not be hashed.
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///
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/// # Panics
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/// Any unnamed struct field (like in a tuple struct) will raise a panic at compile time.
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fn get_hashable_named_field_idents<'a>(struct_data: &'a syn::DataStruct) -> Vec<&'a syn::Ident> {
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struct_data
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.fields
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.iter()
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.filter_map(|f| {
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if should_skip_hashing(&f) {
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None
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} else {
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Some(match &f.ident {
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Some(ref ident) => ident,
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_ => panic!("tree_hash_derive only supports named struct fields."),
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})
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}
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})
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.collect()
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}
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/// Returns true if some field has an attribute declaring it should not be hashedd.
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///
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/// The field attribute is: `#[tree_hash(skip_hashing)]`
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fn should_skip_hashing(field: &syn::Field) -> bool {
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for attr in &field.attrs {
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if attr.tts.to_string() == "( skip_hashing )" {
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return true;
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}
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}
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false
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}
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/// Implements `ssz::Encodable` for some `struct`.
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///
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/// Fields are encoded in the order they are defined.
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#[proc_macro_derive(CachedTreeHashSubTree, attributes(tree_hash))]
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pub fn subtree_derive(input: TokenStream) -> TokenStream {
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let item = parse_macro_input!(input as DeriveInput);
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let name = &item.ident;
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let struct_data = match &item.data {
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syn::Data::Struct(s) => s,
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_ => panic!("tree_hash_derive only supports structs."),
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};
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let idents_a = get_hashable_named_field_idents(&struct_data);
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let idents_b = idents_a.clone();
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let idents_c = idents_a.clone();
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let idents_d = idents_a.clone();
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let output = quote! {
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impl tree_hash::CachedTreeHashSubTree<#name> for #name {
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fn item_type() -> tree_hash::ItemType {
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tree_hash::ItemType::Composite
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}
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fn new_cache(&self) -> Result<tree_hash::TreeHashCache, tree_hash::Error> {
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let tree = tree_hash::TreeHashCache::from_leaves_and_subtrees(
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self,
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vec![
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#(
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self.#idents_a.new_cache()?,
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)*
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],
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)?;
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Ok(tree)
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}
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fn btree_overlay(&self, chunk_offset: usize) -> Result<tree_hash::BTreeOverlay, tree_hash::Error> {
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let mut lengths = vec![];
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#(
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lengths.push(tree_hash::BTreeOverlay::new(&self.#idents_b, 0)?.total_nodes());
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)*
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tree_hash::BTreeOverlay::from_lengths(chunk_offset, lengths)
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}
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fn packed_encoding(&self) -> Result<Vec<u8>, tree_hash::Error> {
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Err(tree_hash::Error::ShouldNeverBePacked(Self::item_type()))
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}
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fn packing_factor() -> usize {
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1
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}
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fn update_cache(
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&self,
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other: &Self,
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cache: &mut tree_hash::TreeHashCache,
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chunk: usize,
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) -> Result<usize, tree_hash::Error> {
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let offset_handler = tree_hash::BTreeOverlay::new(self, chunk)?;
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// Skip past the internal nodes and update any changed leaf nodes.
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{
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let chunk = offset_handler.first_leaf_node()?;
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#(
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let chunk = self.#idents_c.update_cache(&other.#idents_d, cache, chunk)?;
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)*
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}
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for (&parent, children) in offset_handler.iter_internal_nodes().rev() {
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if cache.either_modified(children)? {
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cache.modify_chunk(parent, &cache.hash_children(children)?)?;
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}
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}
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Ok(offset_handler.next_node)
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}
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}
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};
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output.into()
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}
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9
eth2/utils/tree_hash_derive/tests/tests.rs
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9
eth2/utils/tree_hash_derive/tests/tests.rs
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@ -0,0 +1,9 @@
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use tree_hash_derive::CachedTreeHashSubTree;
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#[derive(Clone, Debug, CachedTreeHashSubTree)]
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pub struct Inner {
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pub a: u64,
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pub b: u64,
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pub c: u64,
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pub d: u64,
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}
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