From e6d57685cb4c2708bab004702a6d40d6023e96ca Mon Sep 17 00:00:00 2001
From: RunasSudo <runassudo@yingtongli.me>
Date: Fri, 28 May 2021 22:37:18 +1000
Subject: [PATCH] Some refactoring

---
 src/numbers.rs |  4 +--
 src/stv/mod.rs | 68 +++++++++++++++++---------------------------------
 2 files changed, 24 insertions(+), 48 deletions(-)

diff --git a/src/numbers.rs b/src/numbers.rs
index 07d0fe5..6f52621 100644
--- a/src/numbers.rs
+++ b/src/numbers.rs
@@ -158,9 +158,7 @@ impl ops::Rem for Rational {
 
 impl ops::Add<&Rational> for Rational {
 	type Output = Rational;
-	fn add(self, _rhs: &Rational) -> Self::Output {
-		todo!()
-	}
+	fn add(self, rhs: &Rational) -> Self::Output { Rational(self.0 + &rhs.0) }
 }
 
 impl ops::Sub<&Rational> for Rational {
diff --git a/src/stv/mod.rs b/src/stv/mod.rs
index c7cb92a..877215a 100644
--- a/src/stv/mod.rs
+++ b/src/stv/mod.rs
@@ -89,15 +89,11 @@ fn next_preferences<'a, N: Number>(state: &CountState<'a, N>, votes: Vec<Vote<'a
 }
 
 pub fn distribute_first_preferences<N: Number>(state: &mut CountState<N>) {
-	let mut votes = Vec::new();
-	for ballot in state.election.ballots.iter() {
-		let vote = Vote {
-			ballot: ballot,
-			value: ballot.orig_value.clone(),
-			up_to_pref: 0,
-		};
-		votes.push(vote);
-	}
+	let votes = state.election.ballots.iter().map(|b| Vote {
+		ballot: b,
+		value: b.orig_value.clone(),
+		up_to_pref: 0,
+	}).collect();
 	
 	let result = next_preferences(state, votes);
 	
@@ -117,10 +113,7 @@ pub fn distribute_first_preferences<N: Number>(state: &mut CountState<N>) {
 
 pub fn calculate_quota<N: Number>(state: &mut CountState<N>) {
 	// Calculate the total vote
-	state.quota = N::zero();
-	for count_card in state.candidates.values() {
-		state.quota += &count_card.votes;
-	}
+	state.quota = state.candidates.values().fold(N::zero(), |acc, cc| { acc + &cc.votes });
 	
 	// TODO: Different quotas
 	state.quota /= N::from(state.election.seats + 1);
@@ -136,13 +129,10 @@ fn meets_quota<N: Number>(quota: &N, count_card: &CountCard<N>) -> bool {
 }
 
 pub fn elect_meeting_quota<N: Number>(state: &mut CountState<N>) {
-	// Can't use filter(...) magic because of conflict with borrow checker
-	let mut cands_meeting_quota = Vec::new();
-	for (candidate, count_card) in state.candidates.iter_mut() {
-		if count_card.state == CandidateState::HOPEFUL && meets_quota(&state.quota, count_card) {
-			cands_meeting_quota.push((candidate, count_card));
-		}
-	}
+	let quota = &state.quota; // Have to do this or else the borrow checker gets confused
+	let mut cands_meeting_quota: Vec<(&&Candidate, &mut CountCard<N>)> = state.candidates.iter_mut()
+		.filter(|(_, cc)| cc.state == CandidateState::HOPEFUL && meets_quota(quota, cc))
+		.collect();
 	
 	if cands_meeting_quota.len() > 0 {
 		// Sort by votes
@@ -159,13 +149,9 @@ pub fn elect_meeting_quota<N: Number>(state: &mut CountState<N>) {
 }
 
 pub fn distribute_surpluses<N: Number>(state: &mut CountState<N>) -> bool where for<'r> &'r N: Sub<&'r N, Output=N> {
-	// As above regarding filter(...)
-	let mut has_surplus = Vec::new();
-	for (candidate, count_card) in state.candidates.iter() {
-		if count_card.votes > state.quota {
-			has_surplus.push((candidate, count_card));
-		}
-	}
+	let mut has_surplus: Vec<(&&Candidate, &CountCard<N>)> = state.candidates.iter()
+		.filter(|(_, cc)| cc.votes > state.quota)
+		.collect();
 	
 	if has_surplus.len() > 0 {
 		// TODO: Different sorting orders
@@ -229,12 +215,10 @@ fn distribute_surplus<N: Number>(state: &mut CountState<N>, elected_candidate: &
 pub fn bulk_elect<N: Number>(state: &mut CountState<N>) -> bool {
 	if state.election.candidates.len() - state.num_excluded <= state.election.seats {
 		// Bulk elect all remaining candidates
-		let mut hopefuls = Vec::new();
-		for (candidate, count_card) in state.candidates.iter_mut() {
-			if count_card.state == CandidateState::HOPEFUL {
-				hopefuls.push((candidate, count_card));
-			}
-		}
+		let mut hopefuls: Vec<(&&Candidate, &mut CountCard<N>)> = state.candidates.iter_mut()
+			.filter(|(_, cc)| cc.state == CandidateState::HOPEFUL)
+			.collect();
+		
 		// TODO: Handle ties
 		hopefuls.sort_unstable_by(|a, b| a.1.votes.partial_cmp(&b.1.votes).unwrap());
 		
@@ -250,12 +234,9 @@ pub fn bulk_elect<N: Number>(state: &mut CountState<N>) -> bool {
 }
 
 pub fn exclude_hopefuls<N: Number>(state: &mut CountState<N>) -> bool {
-	let mut hopefuls = Vec::new();
-	for (candidate, count_card) in state.candidates.iter() {
-		if count_card.state == CandidateState::HOPEFUL {
-			hopefuls.push((candidate, count_card));
-		}
-	}
+	let mut hopefuls: Vec<(&&Candidate, &CountCard<N>)> = state.candidates.iter()
+		.filter(|(_, cc)| cc.state == CandidateState::HOPEFUL)
+		.collect();
 	
 	// Sort by votes
 	// TODO: Handle ties
@@ -269,12 +250,9 @@ pub fn exclude_hopefuls<N: Number>(state: &mut CountState<N>) -> bool {
 }
 
 pub fn continue_exclusion<N: Number>(state: &mut CountState<N>) -> bool {
-	let mut excluded_with_votes = Vec::new();
-	for (candidate, count_card) in state.candidates.iter() {
-		if count_card.state == CandidateState::EXCLUDED && !count_card.votes.is_zero() {
-			excluded_with_votes.push((candidate, count_card));
-		}
-	}
+	let mut excluded_with_votes: Vec<(&&Candidate, &CountCard<N>)> = state.candidates.iter()
+		.filter(|(_, cc)| cc.state == CandidateState::EXCLUDED && !cc.votes.is_zero())
+		.collect();
 	
 	if excluded_with_votes.len() > 0 {
 		excluded_with_votes.sort_unstable_by(|a, b| a.1.order_elected.partial_cmp(&b.1.order_elected).unwrap());