Update beacon_state.rs to spec v0.4.0

eth2/types/Cargo.toml

@@ -10,6 +10,7 @@ boolean-bitfield = { path = "../utils/boolean-bitfield" }
 ethereum-types = "0.4.0"
 hashing = { path = "../utils/hashing" }
 honey-badger-split =  { path = "../utils/honey-badger-split" }
+int_to_bytes = { path = "../utils/int_to_bytes" }
 log = "0.4"
 rayon = "1.0"
 rand = "0.5.5"

eth2/types/src/chain_spec.rs

@@ -93,8 +93,20 @@ pub struct ChainSpec {
     pub domain_randao: u64,
     pub domain_transfer: u64,
 }
-
 impl ChainSpec {
+    /// Return the number of committees in one epoch.
+    ///
+    /// Spec v0.4.0
+    pub fn get_epoch_committee_count(&self, active_validator_count: usize) -> u64 {
+        std::cmp::max(
+            1,
+            std::cmp::min(
+                self.shard_count / self.slots_per_epoch,
+                active_validator_count as u64 / self.slots_per_epoch / self.target_committee_size,
+            ),
+        ) * self.slots_per_epoch
+    }
+
     /// Returns a `ChainSpec` compatible with the Ethereum Foundation specification.
     ///
     /// Spec v0.4.0
@@ -190,9 +202,7 @@ impl ChainSpec {
             domain_transfer: 5,
         }
     }
-}
 
-impl ChainSpec {
     /// Returns a `ChainSpec` compatible with the specification suitable for 8 validators.
     ///
     /// Spec v0.4.0

eth2/types/src/fork.rs

@@ -16,6 +16,8 @@ pub struct Fork {
 
 impl Fork {
     /// Return the fork version of the given ``epoch``.
+    ///
+    /// Spec v0.4.0
     pub fn get_fork_version(&self, epoch: Epoch) -> u64 {
         if epoch < self.epoch {
             return self.previous_version;
@@ -24,6 +26,8 @@ impl Fork {
     }
 
     /// Get the domain number that represents the fork meta and signature domain.
+    ///
+    /// Spec v0.4.0
     pub fn get_domain(&self, epoch: Epoch, domain_type: u64) -> u64 {
         let fork_version = self.get_fork_version(epoch);
         fork_version * u64::pow(2, 32) + domain_type

eth2/types/src/readers/state_reader.rs

@@ -1,4 +1,4 @@
-use crate::{BeaconState, Hash256, Slot};
+use crate::{BeaconState, Slot};
 use std::fmt::Debug;
 
 /// The `BeaconStateReader` provides interfaces for reading a subset of fields of a `BeaconState`.
@@ -11,7 +11,6 @@ use std::fmt::Debug;
 /// "future proofing".
 pub trait BeaconStateReader: Debug + PartialEq {
     fn slot(&self) -> Slot;
-    fn canonical_root(&self) -> Hash256;
     fn into_beacon_state(self) -> Option<BeaconState>;
 }
 
@@ -20,10 +19,6 @@ impl BeaconStateReader for BeaconState {
         self.slot
     }
 
-    fn canonical_root(&self) -> Hash256 {
-        self.canonical_root()
-    }
-
     fn into_beacon_state(self) -> Option<BeaconState> {
         Some(self)
     }

eth2/types/src/validator_registry.rs

@@ -4,6 +4,8 @@ use super::validator::*;
 use crate::Epoch;
 
 /// Given an indexed sequence of `validators`, return the indices corresponding to validators that are active at `epoch`.
+///
+/// Spec v0.4.0
 pub fn get_active_validator_indices(validators: &[Validator], epoch: Epoch) -> Vec<usize> {
     validators
         .iter()