From ca73fb72da36712b994ae9ae96f7f70b0c6847eb Mon Sep 17 00:00:00 2001
From: Michael Sproul <michael@sigmaprime.io>
Date: Mon, 13 May 2019 17:15:30 +1000
Subject: [PATCH] state_processing: get_attesting_indices

---
 .../get_attestation_participants.rs           | 38 -------------------
 .../get_attesting_indices.rs                  | 32 ++++++++++++++++
 2 files changed, 32 insertions(+), 38 deletions(-)
 delete mode 100644 eth2/state_processing/src/per_epoch_processing/get_attestation_participants.rs
 create mode 100644 eth2/state_processing/src/per_epoch_processing/get_attesting_indices.rs

diff --git a/eth2/state_processing/src/per_epoch_processing/get_attestation_participants.rs b/eth2/state_processing/src/per_epoch_processing/get_attestation_participants.rs
deleted file mode 100644
index bea772204c..0000000000
--- a/eth2/state_processing/src/per_epoch_processing/get_attestation_participants.rs
+++ /dev/null
@@ -1,38 +0,0 @@
-use crate::common::verify_bitfield_length;
-use types::*;
-
-/// Returns validator indices which participated in the attestation.
-///
-/// Spec v0.5.1
-pub fn get_attestation_participants(
-    state: &BeaconState,
-    attestation_data: &AttestationData,
-    bitfield: &Bitfield,
-    spec: &ChainSpec,
-) -> Result<Vec<usize>, BeaconStateError> {
-    let epoch = attestation_data.slot.epoch(spec.slots_per_epoch);
-
-    let crosslink_committee =
-        state.get_crosslink_committee_for_shard(epoch, attestation_data.shard, spec)?;
-
-    if crosslink_committee.slot != attestation_data.slot {
-        return Err(BeaconStateError::NoCommitteeForShard);
-    }
-
-    let committee = &crosslink_committee.committee;
-
-    if !verify_bitfield_length(&bitfield, committee.len()) {
-        return Err(BeaconStateError::InvalidBitfield);
-    }
-
-    let mut participants = Vec::with_capacity(committee.len());
-    for (i, validator_index) in committee.iter().enumerate() {
-        match bitfield.get(i) {
-            Ok(bit) if bit => participants.push(*validator_index),
-            _ => {}
-        }
-    }
-    participants.shrink_to_fit();
-
-    Ok(participants)
-}
diff --git a/eth2/state_processing/src/per_epoch_processing/get_attesting_indices.rs b/eth2/state_processing/src/per_epoch_processing/get_attesting_indices.rs
new file mode 100644
index 0000000000..181aedae1b
--- /dev/null
+++ b/eth2/state_processing/src/per_epoch_processing/get_attesting_indices.rs
@@ -0,0 +1,32 @@
+use crate::common::verify_bitfield_length;
+use types::*;
+
+/// Returns validator indices which participated in the attestation.
+///
+/// Spec v0.6.1
+pub fn get_attesting_indices_unsorted(
+    state: &BeaconState,
+    attestation_data: &AttestationData,
+    bitfield: &Bitfield,
+    spec: &ChainSpec,
+) -> Result<Vec<usize>, BeaconStateError> {
+    let committee = state.get_crosslink_committee(
+        attestation_data.target_epoch,
+        attestation_data.shard,
+        spec,
+    )?;
+
+    if !verify_bitfield_length(&bitfield, committee.committee.len()) {
+        return Err(BeaconStateError::InvalidBitfield);
+    }
+
+    Ok(committee
+        .committee
+        .iter()
+        .enumerate()
+        .filter_map(|(i, validator_index)| match bitfield.get(i) {
+            Ok(true) => Some(*validator_index),
+            _ => None,
+        })
+        .collect())
+}