From c9b189fefedbcbfb93bb0f59e4a8c390563c8521 Mon Sep 17 00:00:00 2001
From: RunasSudo <runassudo@yingtongli.me>
Date: Fri, 10 Sep 2021 01:42:42 +1000
Subject: [PATCH] Update quota/VRE in certain rare cases

---
 src/stv/mod.rs | 89 +++++++++++++++++++++++++++++---------------------
 1 file changed, 52 insertions(+), 37 deletions(-)

diff --git a/src/stv/mod.rs b/src/stv/mod.rs
index bc16897..ba958ca 100644
--- a/src/stv/mod.rs
+++ b/src/stv/mod.rs
@@ -840,6 +840,44 @@ fn update_vre_ers<N: Number>(state: &mut CountState<N>, opts: &STVOptions) {
 	}
 }
 
+/// Update vote required for election if only one candidate remains, used in early bulk election
+///
+/// Assumes early bulk election is enabled.
+fn update_vre_bulk<N: Number>(state: &mut CountState<N>, _opts: &STVOptions) {
+	// If --early-bulk-elect and one candidate remains, VRE is half of the active vote
+	// For display purposes only
+	
+	if state.election.seats - state.num_elected == 1 {
+		//let mut log = String::new();
+		
+		// Calculate active vote
+		let active_vote = state.candidates.values().fold(N::zero(), |acc, cc| {
+			match cc.state {
+				CandidateState::Elected => { if !cc.finalised && &cc.votes > state.quota.as_ref().unwrap() { acc + &cc.votes - state.quota.as_ref().unwrap() } else { acc } }
+				_ => { acc + &cc.votes }
+			}
+		});
+		//log.push_str(format!("Active vote is {:.dps$}, so the vote required for election is ", active_vote, dps=opts.pp_decimals).as_str());
+		
+		let vote_req = active_vote / N::from(state.election.seats - state.num_elected + 1);
+		
+		if &vote_req < state.quota.as_ref().unwrap() {
+			// VRE is less than the quota
+			//if let Some(v) = &state.vote_required_election {
+			//	if &vote_req != v {
+					//log.push_str(format!("{:.dps$}.", vote_req, dps=opts.pp_decimals).as_str());
+					state.vote_required_election = Some(vote_req);
+					//state.logger.log_literal(log);
+			//	}
+			//} else {
+				//log.push_str(format!("{:.dps$}.", vote_req, dps=opts.pp_decimals).as_str());
+			//	state.vote_required_election = Some(vote_req);
+				//state.logger.log_literal(log);
+			//}
+		}
+	}
+}
+
 /// Calculate the quota according to [STVOptions::quota]
 fn calculate_quota<N: Number>(state: &mut CountState<N>, opts: &STVOptions) {
 	if state.quota.is_none() || opts.quota_mode == QuotaMode::DynamicByTotal {
@@ -910,36 +948,8 @@ fn calculate_quota<N: Number>(state: &mut CountState<N>, opts: &STVOptions) {
 	} else {
 		// No ERS97/ERS76 rules
 		
-		// If --early-bulk-elect and one candidate remains, VRE is half of the active vote
-		// For display purposes only
-		if opts.early_bulk_elect && (state.election.seats - state.num_elected) == 1 {
-			//let mut log = String::new();
-			
-			// Calculate active vote
-			let active_vote = state.candidates.values().fold(N::zero(), |acc, cc| {
-				match cc.state {
-					CandidateState::Elected => { if !cc.finalised && &cc.votes > state.quota.as_ref().unwrap() { acc + &cc.votes - state.quota.as_ref().unwrap() } else { acc } }
-					_ => { acc + &cc.votes }
-				}
-			});
-			//log.push_str(format!("Active vote is {:.dps$}, so the vote required for election is ", active_vote, dps=opts.pp_decimals).as_str());
-			
-			let vote_req = active_vote / N::from(state.election.seats - state.num_elected + 1);
-			
-			if &vote_req < state.quota.as_ref().unwrap() {
-				// VRE is less than the quota
-				//if let Some(v) = &state.vote_required_election {
-				//	if &vote_req != v {
-						//log.push_str(format!("{:.dps$}.", vote_req, dps=opts.pp_decimals).as_str());
-						state.vote_required_election = Some(vote_req);
-						//state.logger.log_literal(log);
-				//	}
-				//} else {
-					//log.push_str(format!("{:.dps$}.", vote_req, dps=opts.pp_decimals).as_str());
-				//	state.vote_required_election = Some(vote_req);
-					//state.logger.log_literal(log);
-				//}
-			}
+		if opts.early_bulk_elect {
+			update_vre_bulk(state, opts);
 		}
 	}
 }
@@ -1119,17 +1129,22 @@ fn elect_hopefuls<'a, N: Number>(state: &mut CountState<'a, N>, opts: &STVOption
 			cands_meeting_quota.remove(cands_meeting_quota.iter().position(|c| *c == candidate).unwrap());
 		}
 		
-		if opts.quota_mode == QuotaMode::ERS97 || (opts.quota_mode == QuotaMode::ERS76 && elected_on_quota) {
+		if opts.quota_mode == QuotaMode::ERS97 || opts.quota_mode == QuotaMode::ERS76 || opts.quota_mode == QuotaMode::DynamicByActive {
 			// Vote required for election may have changed
 			// ERS97: Check this after every elected candidate (cf. model election)
 			// ERS76: Check this after every candidate elected on a quota, but all at once for candidates elected on VRE (cf. model election)
-			calculate_quota(state, opts);
-			
-			// Repeat in case vote required for election has changed
-			match elect_hopefuls(state, opts, true) {
-				Ok(_) => { break; }
-				Err(e) => { return Err(e); }
+			if opts.quota_mode == QuotaMode::ERS97 || (opts.quota_mode == QuotaMode::ERS76 && elected_on_quota) || opts.quota_mode == QuotaMode::DynamicByActive {
+				calculate_quota(state, opts);
+				
+				// Repeat in case vote required for election has changed
+				match elect_hopefuls(state, opts, true) {
+					Ok(_) => { break; }
+					Err(e) => { return Err(e); }
+				}
 			}
+		} else if opts.early_bulk_elect {
+			// Vote required for election may have changed for display purposes
+			update_vre_bulk(state, opts);
 		}
 	}