mirror of
https://github.com/pezkuwichain/pezkuwi-subxt.git
synced 2026-06-13 19:51:05 +00:00
Benjamin Kampmann
927e13c13a
* Adding script for rename, could be applicable for nodes on top of it, too * add stderr and gitlab ci features * apply script * fix now minor details in expected stderr * Update the Cargo.lock * fix name: sc-transaction -> sc-tracing * fix rename in script, too
103 lines
3.8 KiB
Rust
103 lines
3.8 KiB
Rust
// Copyright 2017-2019 Parity Technologies (UK) Ltd.
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// This file is part of Substrate.
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// Substrate is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Substrate is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Substrate. If not, see <http://www.gnu.org/licenses/>.
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//! Voting thresholds.
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#[cfg(feature = "std")]
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use serde::{Serialize, Deserialize};
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use codec::{Encode, Decode};
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use sp_runtime::traits::{Zero, IntegerSquareRoot};
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use rstd::ops::{Add, Mul, Div, Rem};
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/// A means of determining if a vote is past pass threshold.
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#[derive(Clone, Copy, PartialEq, Eq, Encode, Decode, sp_runtime::RuntimeDebug)]
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#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
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pub enum VoteThreshold {
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/// A supermajority of approvals is needed to pass this vote.
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SuperMajorityApprove,
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/// A supermajority of rejects is needed to fail this vote.
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SuperMajorityAgainst,
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/// A simple majority of approvals is needed to pass this vote.
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SimpleMajority,
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}
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pub trait Approved<Balance> {
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/// Given `approve` votes for and `against` votes against from a total electorate size of
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/// `electorate` (`electorate - (approve + against)` are abstainers), then returns true if the
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/// overall outcome is in favor of approval.
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fn approved(&self, approve: Balance, against: Balance, voters: Balance, electorate: Balance) -> bool;
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}
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/// Return `true` iff `n1 / d1 < n2 / d2`. `d1` and `d2` may not be zero.
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fn compare_rationals<T: Zero + Mul<T, Output = T> + Div<T, Output = T> + Rem<T, Output = T> + Ord + Copy>(mut n1: T, mut d1: T, mut n2: T, mut d2: T) -> bool {
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// Uses a continued fractional representation for a non-overflowing compare.
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// Detailed at https://janmr.com/blog/2014/05/comparing-rational-numbers-without-overflow/.
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loop {
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let q1 = n1 / d1;
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let q2 = n2 / d2;
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if q1 < q2 {
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return true;
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}
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if q2 < q1 {
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return false;
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}
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let r1 = n1 % d1;
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let r2 = n2 % d2;
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if r2.is_zero() {
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return false;
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}
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if r1.is_zero() {
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return true;
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}
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n1 = d2;
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n2 = d1;
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d1 = r2;
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d2 = r1;
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}
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}
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impl<Balance: IntegerSquareRoot + Zero + Ord + Add<Balance, Output = Balance> + Mul<Balance, Output = Balance> + Div<Balance, Output = Balance> + Rem<Balance, Output = Balance> + Copy> Approved<Balance> for VoteThreshold {
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/// Given `approve` votes for and `against` votes against from a total electorate size of
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/// `electorate` of whom `voters` voted (`electorate - voters` are abstainers) then returns true if the
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/// overall outcome is in favor of approval.
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///
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/// We assume each *voter* may cast more than one *vote*, hence `voters` is not necessarily equal to
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/// `approve + against`.
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fn approved(&self, approve: Balance, against: Balance, voters: Balance, electorate: Balance) -> bool {
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let sqrt_voters = voters.integer_sqrt();
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let sqrt_electorate = electorate.integer_sqrt();
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if sqrt_voters.is_zero() { return false; }
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match *self {
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VoteThreshold::SuperMajorityApprove =>
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compare_rationals(against, sqrt_voters, approve, sqrt_electorate),
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VoteThreshold::SuperMajorityAgainst =>
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compare_rationals(against, sqrt_electorate, approve, sqrt_voters),
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VoteThreshold::SimpleMajority => approve > against,
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn should_work() {
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assert_eq!(VoteThreshold::SuperMajorityApprove.approved(60, 50, 110, 210), false);
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assert_eq!(VoteThreshold::SuperMajorityApprove.approved(100, 50, 150, 210), true);
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}
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}
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