Move shuffling functions around

- Move `delegation` from the `transition` dir into its own dir:
`beacon_chain/validator_shuffling`
- Rename `beacon_chain/utils/shuffling` -> `vec_shuffle`

Cargo.toml

@@ -33,15 +33,15 @@ name = "lighthouse"
 [workspace]
 members = [
 	"beacon_chain/types",
-	"beacon_chain/transition",
 	"beacon_chain/utils/bls",
 	"beacon_chain/utils/boolean-bitfield",
 	"beacon_chain/utils/hashing",
 	"beacon_chain/utils/honey-badger-split",
-	"beacon_chain/utils/shuffling",
 	"beacon_chain/utils/ssz",
 	"beacon_chain/utils/ssz_helpers",
+	"beacon_chain/utils/vec_shuffle",
 	"beacon_chain/validation",
 	"beacon_chain/validator_induction",
+	"beacon_chain/validator_shuffling",
 	"lighthouse/db",
 ]

beacon_chain/transition/src/delegation/mod.rs

@@ -1,6 +0,0 @@
-use super::honey_badger_split;
-use super::types;
-use super::TransitionError;
-use super::shuffling::shuffle;
-
-pub mod validator;

beacon_chain/transition/src/lib.rs

@@ -1,10 +0,0 @@
-extern crate honey_badger_split;
-extern crate types;
-extern crate shuffling;
-
-pub mod delegation;
-
-#[derive(Debug)]
-pub enum TransitionError {
-	InvalidInput(String),
-}

beacon_chain/utils/vec_shuffle/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "shuffling"
+name = "vec_shuffle"
 version = "0.1.0"
 authors = ["Paul Hauner <paul@paulhauner.com>"]
 

beacon_chain/validator_induction/src/lib.rs

@@ -10,3 +10,7 @@ pub use inductor::{
     ValidatorInductor,
     ValidatorInductionError,
 };
+
+pub use registration::{
+    ValidatorRegistration,
+};

beacon_chain/validator_shuffling/Cargo.toml

@@ -1,9 +1,9 @@
 [package]
-name = "transition"
+name = "validator_shuffling"
 version = "0.1.0"
-authors = ["Age Manning <Age@AgeManning.com>"]
+authors = ["Paul Hauner <paul@paulhauner.com>"]
 
 [dependencies]
 honey-badger-split = { path = "../utils/honey-badger-split" }
 types = { path = "../types" }
-shuffling = { path = "../utils/shuffling" }
+vec_shuffle = { path = "../utils/vec_shuffle" }

beacon_chain/validator_shuffling/src/active_validator_indices.rs

@@ -0,0 +1,19 @@
+use types::{
+    ValidatorRecord,
+    ValidatorStatus,
+};
+
+/// Returns the indicies of each active validator in a given vec of validators.
+pub fn active_validator_indices(validators: &[ValidatorRecord])
+    -> Vec<usize>
+{
+    validators.iter()
+        .enumerate()
+        .filter_map(|(i, validator)| {
+            match validator.status {
+                x if x == ValidatorStatus::Active as u8 => Some(i),
+                _ => None
+            }
+        })
+        .collect()
+}

beacon_chain/validator_shuffling/src/lib.rs

@@ -0,0 +1,8 @@
+extern crate honey_badger_split;
+extern crate vec_shuffle;
+extern crate types;
+
+mod active_validator_indices;
+mod shuffle;
+
+pub use shuffle::shard_and_committees_for_cycle;

beacon_chain/validator_shuffling/src/shuffle.rs

@@ -1,29 +1,20 @@
-use super::honey_badger_split::SplitExt;
-use super::types::{
+use std::cmp::min;
+
+use honey_badger_split::SplitExt;
+use vec_shuffle::shuffle;
+use types::{
     ShardAndCommittee,
     ValidatorRecord,
-    ValidatorStatus,
     ChainConfig,
 };
-use super::TransitionError;
-use super::shuffle;
-use std::cmp::min;
+
+use super::active_validator_indices::active_validator_indices;
 
 type DelegatedCycle = Vec<Vec<ShardAndCommittee>>;
 
-/// Returns the indicies of each active validator in a given vec of validators.
-fn active_validator_indicies(validators: &[ValidatorRecord])
-    -> Vec<usize>
-{
-    validators.iter()
-        .enumerate()
-        .filter_map(|(i, validator)| {
-            match validator.status {
-                x if x == ValidatorStatus::Active as u8 => Some(i),
-                _ => None
-            }
-        })
-        .collect()
+#[derive(Debug)]
+pub enum TransitionError {
+	InvalidInput(String),
 }
 
 
@@ -31,7 +22,7 @@ fn active_validator_indicies(validators: &[ValidatorRecord])
 /// Returns a vector or ShardAndComitte vectors representing the shards and committiees for
 /// each slot.
 /// References get_new_shuffling (ethereum 2.1 specification)
-pub fn delegate_validators(
+pub fn shard_and_committees_for_cycle(
     seed: &[u8],
     validators: &[ValidatorRecord],
     crosslinking_shard_start: u16,
@@ -39,7 +30,7 @@ pub fn delegate_validators(
     -> Result<DelegatedCycle, TransitionError>
 {
     let shuffled_validator_indices = {
-        let mut validator_indices = active_validator_indicies(validators);
+        let mut validator_indices = active_validator_indices(validators);
         match shuffle(seed, validator_indices) {
             Ok(shuffled) => shuffled,
             _ => return Err(TransitionError::InvalidInput(