Initial framework for equal rankings

coverage.sh

@@ -14,6 +14,7 @@ llvm-profdata merge -sparse target/coverage/prof/*.profraw -o target/coverage/op
 eval llvm-cov show target/coverage/debug/opentally -instr-profile=target/coverage/opentally.profdata -Xdemangler="$HOME/.cargo/bin/rustfilt" \
 	$(for file in $(cargo test --no-run --message-format=json 2>/dev/null | jq -r "select(.profile.test == true) | .filenames[]"); do echo -n --object '"'$file'" '; done) \
 	-ignore-filename-regex="$HOME/." \
+	-ignore-filename-regex=rustc \
 	-ignore-filename-regex=numbers/rational_num.rs \
 	-ignore-filename-regex=stv/wasm.rs \
 	-ignore-filename-regex=tests \

html/worker.js

@@ -44,10 +44,14 @@ onmessage = function(evt) {
 			// Init election
 			election = wasm['election_from_blt_' + numbers](evt.data.bltData);
 			
+			// Normalise ballots if requested
 			if (evt.data.normaliseBallots) {
 				wasm['election_normalise_ballots_' + numbers](election);
 			}
 			
+			// Process equal rankings
+			wasm['election_realise_equal_rankings_' + numbers](election);
+			
 			// Init constraints if applicable
 			if (evt.data.conData) {
 				wasm['election_load_constraints_' + numbers](election, evt.data.conData);

src/cli/stv.rs

@@ -309,6 +309,9 @@ where
 		election.normalise_ballots();
 	}
 	
+	// Process equal rankings
+	election.realise_equal_rankings();
+	
 	// Initialise count state
 	let mut state = CountState::new(&election);
 	

src/election.rs

@@ -47,6 +47,8 @@ pub struct Election<N> {
 
 impl<N: Number> Election<N> {
 	/// Convert ballots with weight >1 to multiple ballots of weight 1
+	///
+	/// Assumes ballots have integer weight.
 	pub fn normalise_ballots(&mut self) {
 		let mut normalised_ballots = Vec::new();
 		for ballot in self.ballots.iter() {
@@ -63,6 +65,16 @@ impl<N: Number> Election<N> {
 		}
 		self.ballots = normalised_ballots;
 	}
+	
+	/// Convert ballots with equal rankings to strict-preference "minivoters"
+	pub fn realise_equal_rankings(&mut self) {
+		let mut realised_ballots = Vec::new();
+		for ballot in self.ballots.iter() {
+			let mut b = ballot.realise_equal_rankings();
+			realised_ballots.append(&mut b);
+		}
+		self.ballots = realised_ballots;
+	}
 }
 
 /// A candidate in an [Election]
@@ -74,7 +86,6 @@ pub struct Candidate {
 }
 
 /// The current state of counting an [Election]
-//#[derive(Clone)]
 pub struct CountState<'a, N: Number> {
 	/// Pointer to the [Election] being counted
 	pub election: &'a Election<N>,
@@ -368,6 +379,22 @@ pub struct Vote<'a, N> {
 	pub up_to_pref: usize,
 }
 
+impl<'a, N> Vote<'a, N> {
+	/// Get the next preference and increment `up_to_pref`
+	///
+	/// Assumes that each preference level contains only one preference.
+	pub fn next_preference(&mut self) -> Option<usize> {
+		if self.up_to_pref >= self.ballot.preferences.len() {
+			return None;
+		}
+		
+		let preference = &self.ballot.preferences[self.up_to_pref];
+		self.up_to_pref += 1;
+		
+		return Some(*preference.first().unwrap());
+	}
+}
+
 /// A record of a voter's preferences
 #[derive(Clone)]
 #[cfg_attr(not(target_arch = "wasm32"), derive(Archive, Deserialize, Serialize))]
@@ -375,8 +402,32 @@ pub struct Ballot<N> {
 	/// Original value/weight of the ballot
 	#[cfg_attr(not(target_arch = "wasm32"), with(SerializedNum))]
 	pub orig_value: N,
-	/// Indexes of candidates preferenced on the ballot
-	pub preferences: Vec<usize>,
+	/// Indexes of candidates preferenced at each level on the ballot
+	pub preferences: Vec<Vec<usize>>,
+}
+
+impl<N: Number> Ballot<N> {
+	/// Convert ballot with equal rankings to strict-preference "minivoters"
+	pub fn realise_equal_rankings(&self) -> Vec<Ballot<N>> {
+		// Preferences for each minivoter
+		let mut minivoters = vec![Vec::new()];
+		
+		for preference in self.preferences.iter() {
+			if preference.len() == 1 {
+				for minivoter in minivoters.iter_mut() {
+					minivoter.push(preference.clone());
+				}
+			} else {
+				todo!();
+			}
+		}
+		
+		let weight_each = self.orig_value.clone() / N::from(minivoters.len());
+		let ballots = minivoters.into_iter()
+			.map(|p| Ballot { orig_value: weight_each.clone(), preferences: p })
+			.collect();
+		return ballots;
+	}
 }
 
 /// rkyv-serialized representation of [Number]

src/parser/blt.rs

@@ -151,7 +151,7 @@ impl<N: Number, I: Iterator<Item=char>> BLTParser<N, I> {
 				self.accept();
 				break;
 			} else {
-				preferences.push(self.usize()? - 1);
+				preferences.push(vec![self.usize()? - 1]);
 				self.delimiter_not_nl();
 			}
 		}

src/parser/csp.rs

@@ -87,7 +87,7 @@ pub fn parse_reader<R: Read, N: Number>(reader: R) -> Election<N> {
 		
 		ballots.push(Ballot {
 			orig_value: value,
-			preferences: preferences.into_iter().map(|(_, i)| *i).collect(),
+			preferences: preferences.into_iter().map(|(_, i)| vec![*i]).collect(),
 		});
 	}
 	

src/stv/meek.rs

@@ -60,7 +60,13 @@ impl<'t, N: Number> BallotTree<'t, N> {
 		
 		for bit in self.ballots.iter() {
 			if bit.up_to_pref < bit.ballot.preferences.len() {
-				let candidate = &candidates[bit.ballot.preferences[bit.up_to_pref]];
+				let preference = &bit.ballot.preferences[bit.up_to_pref];
+				
+				if preference.len() != 1 {
+					todo!();
+				}
+				
+				let candidate = &candidates[*preference.first().unwrap()];
 				
 				if next_preferences.contains_key(candidate) {
 					let np_bt = next_preferences.get_mut(candidate).unwrap();

src/stv/mod.rs

@@ -692,14 +692,18 @@ fn next_preferences<'a, N: Number>(state: &CountState<'a, N>, votes: Vec<Vote<'a
 		
 		let mut next_candidate = None;
 		
-		for (i, preference) in vote.ballot.preferences.iter().enumerate().skip(vote.up_to_pref) {
-			let candidate = &state.election.candidates[*preference];
-			let count_card = &state.candidates[candidate];
+		loop {
+			match vote.next_preference() {
+				Some(preference) => {
+					let candidate = &state.election.candidates[preference];
+					let count_card = &state.candidates[candidate];
 					
-			if let CandidateState::Hopeful | CandidateState::Guarded = count_card.state {
-				next_candidate = Some(candidate);
-				vote.up_to_pref = i + 1;
-				break;
+					if let CandidateState::Hopeful | CandidateState::Guarded = count_card.state {
+						next_candidate = Some(candidate);
+						break;
+					}
+				}
+				None => { break; }
 			}
 		}
 		

src/stv/sample.rs

@@ -275,14 +275,19 @@ where
 fn transfer_ballot<'a, N: Number>(state: &mut CountState<'a, N>, opts: &STVOptions, source_candidate: &Candidate, mut vote: Vote<'a, N>, ignore_nontransferable: bool) -> Result<(), STVError> {
 	// Get next preference
 	let mut next_candidate = None;
-	for (i, preference) in vote.ballot.preferences.iter().enumerate().skip(vote.up_to_pref) {
-		let candidate = &state.election.candidates[*preference];
-		let count_card = &state.candidates[candidate];
 	
-		if let CandidateState::Hopeful | CandidateState::Guarded = count_card.state {
-			next_candidate = Some(candidate);
-			vote.up_to_pref = i + 1;
-			break;
+	loop {
+		match vote.next_preference() {
+			Some(preference) => {
+				let candidate = &state.election.candidates[preference];
+				let count_card = &state.candidates[candidate];
+				
+				if let CandidateState::Hopeful | CandidateState::Guarded = count_card.state {
+					next_candidate = Some(candidate);
+					break;
+				}
+			}
+			None => { break; }
 		}
 	}
 	

src/stv/wasm.rs

@@ -87,6 +87,13 @@ macro_rules! impl_type {
 			election.0.normalise_ballots();
 		}
 		
+		/// Wrapper for [Election::realise_equal_rankings]
+		#[wasm_bindgen]
+		#[allow(non_snake_case)]
+		pub fn [<election_realise_equal_rankings_$type>](election: &mut [<Election$type>]) {
+			election.0.realise_equal_rankings();
+		}
+		
 		/// Call [Constraints::from_con] and set [Election::constraints]
 		#[wasm_bindgen]
 		#[allow(non_snake_case)]

src/writer/blt.rs

@@ -40,7 +40,7 @@ pub fn write<W: Write, N: Number>(election: Election<N>, output: W) {
 		output.write_fmt(format_args!("{}", ballot.orig_value)).expect("IO Error");
 		
 		for preference in ballot.preferences {
-			output.write_fmt(format_args!(" {}", preference + 1)).expect("IO Error");
+			output.write_fmt(format_args!(" {}", preference.into_iter().map(|p| p + 1).join("="))).expect("IO Error");
 		}
 		
 		output.write(b" 0\n").expect("IO Error");

src/writer/csp.rs

@@ -40,7 +40,9 @@ pub fn write<W: Write, N: Number>(election: Election<N>, output: W) {
 		// Code preferences to rankings
 		let mut rankings = vec![0_usize; election.candidates.len()];
 		for (i, preference) in ballot.preferences.into_iter().enumerate() {
-			rankings[preference] = i + 1;
+			for p in preference {
+				rankings[p] = i + 1;
+			}
 		}
 		
 		// Write rankings