Rename all the election operations (#6245)

* Rename and move sp-phragmen

* More renames for equalise

* Update main module doc

* Fix line width

* Line width

substrate/primitives/npos-elections/src/helpers.rs

@@ -0,0 +1,99 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2020 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Helper methods for npos-elections.
+
+use crate::{Assignment, ExtendedBalance, VoteWeight, IdentifierT, StakedAssignment, WithApprovalOf};
+use sp_arithmetic::PerThing;
+use sp_std::prelude::*;
+
+/// Converts a vector of ratio assignments into ones with absolute budget value.
+pub fn assignment_ratio_to_staked<A: IdentifierT, T: PerThing, FS>(
+	ratio: Vec<Assignment<A, T>>,
+	stake_of: FS,
+) -> Vec<StakedAssignment<A>>
+where
+	for<'r> FS: Fn(&'r A) -> VoteWeight,
+	T: sp_std::ops::Mul<ExtendedBalance, Output = ExtendedBalance>,
+	ExtendedBalance: From<<T as PerThing>::Inner>,
+{
+	ratio
+		.into_iter()
+		.map(|a| {
+			let stake = stake_of(&a.who);
+			a.into_staked(stake.into(), true)
+		})
+		.collect()
+}
+
+/// Converts a vector of staked assignments into ones with ratio values.
+pub fn assignment_staked_to_ratio<A: IdentifierT, T: PerThing>(
+	staked: Vec<StakedAssignment<A>>,
+) -> Vec<Assignment<A, T>>
+where
+	ExtendedBalance: From<<T as PerThing>::Inner>,
+{
+	staked.into_iter().map(|a| a.into_assignment(true)).collect()
+}
+
+/// consumes a vector of winners with backing stake to just winners.
+pub fn to_without_backing<A: IdentifierT>(winners: Vec<WithApprovalOf<A>>) -> Vec<A> {
+	winners.into_iter().map(|(who, _)| who).collect::<Vec<A>>()
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use sp_arithmetic::Perbill;
+
+	#[test]
+	fn into_staked_works() {
+		let assignments = vec![
+			Assignment {
+				who: 1u32,
+				distribution: vec![
+					(10u32, Perbill::from_fraction(0.5)),
+					(20, Perbill::from_fraction(0.5)),
+				],
+			},
+			Assignment {
+				who: 2u32,
+				distribution: vec![
+					(10, Perbill::from_fraction(0.33)),
+					(20, Perbill::from_fraction(0.67)),
+				],
+			},
+		];
+
+		let stake_of = |_: &u32| -> VoteWeight { 100 };
+		let staked = assignment_ratio_to_staked(assignments, stake_of);
+
+		assert_eq!(
+			staked,
+			vec![
+				StakedAssignment {
+					who: 1u32,
+					distribution: vec![(10u32, 50), (20, 50),]
+				},
+				StakedAssignment {
+					who: 2u32,
+					distribution: vec![(10u32, 33), (20, 67),]
+				}
+			]
+		);
+	}
+}