Redesign Democracy pallet (#5294)

* Repot a bit of democracy code

* Basic logic is drafted

* Lazy democracy builds.

* Add non-locked split-voting and instant-scheduling.

* Introduce delegation that works.

* Builds again.

* Indentation

* Building.

* Docs and migration

* Fix half of the tests

* Fix up & repot tests

* Fix runtime build

* Update docs

* Docs

* Nits.

* Turnout counts full capital

* Delegations could towards capital

* proxy delegation & proxy unvoting

* Fix

* Tests for split-voting

* Add missing file

* Persistent locking.

substrate/frame/democracy/src/vote.rs

@@ -0,0 +1,181 @@
+// Copyright 2017-2020 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! The vote datatype.
+
+use sp_std::{prelude::*, result::Result, convert::TryFrom};
+use codec::{Encode, EncodeLike, Decode, Output, Input};
+use sp_runtime::{RuntimeDebug, traits::{Saturating, Zero}};
+use crate::{Conviction, ReferendumIndex, Delegations};
+
+/// A number of lock periods, plus a vote, one way or the other.
+#[derive(Copy, Clone, Eq, PartialEq, Default, RuntimeDebug)]
+pub struct Vote {
+	pub aye: bool,
+	pub conviction: Conviction,
+}
+
+impl Encode for Vote {
+	fn encode_to<T: Output>(&self, output: &mut T) {
+		output.push_byte(u8::from(self.conviction) | if self.aye { 0b1000_0000 } else { 0 });
+	}
+}
+
+impl EncodeLike for Vote {}
+
+impl Decode for Vote {
+	fn decode<I: Input>(input: &mut I) -> Result<Self, codec::Error> {
+		let b = input.read_byte()?;
+		Ok(Vote {
+			aye: (b & 0b1000_0000) == 0b1000_0000,
+			conviction: Conviction::try_from(b & 0b0111_1111)
+				.map_err(|_| codec::Error::from("Invalid conviction"))?,
+		})
+	}
+}
+
+/// A vote for a referendum of a particular account.
+#[derive(Encode, Decode, Copy, Clone, Eq, PartialEq, RuntimeDebug)]
+pub enum AccountVote<Balance> {
+	/// A standard vote, one-way (approve or reject) with a given amount of conviction.
+	Standard { vote: Vote, balance: Balance },
+	/// A split vote with balances given for both ways, and with no conviction, useful for
+	/// parachains when voting.
+	Split { aye: Balance, nay: Balance },
+}
+
+impl<Balance: Saturating> AccountVote<Balance> {
+	/// Returns `Some` of the lock periods that the account is locked for, assuming that the
+	/// referendum passed iff `approved` is `true`.
+	pub fn locked_if(self, approved: bool) -> Option<(u32, Balance)> {
+		// winning side: can only be removed after the lock period ends.
+		match self {
+			AccountVote::Standard { vote, balance } if vote.aye == approved =>
+				Some((vote.conviction.lock_periods(), balance)),
+			_ => None,
+		}
+	}
+
+	/// The total balance involved in this vote.
+	pub fn balance(self) -> Balance {
+		match self {
+			AccountVote::Standard { balance, .. } => balance,
+			AccountVote::Split { aye, nay } => aye.saturating_add(nay),
+		}
+	}
+
+	/// Returns `Some` with whether the vote is an aye vote if it is standard, otherwise `None` if
+	/// it is split.
+	pub fn as_standard(self) -> Option<bool> {
+		match self {
+			AccountVote::Standard { vote, .. } => Some(vote.aye),
+			_ => None,
+		}
+	}
+}
+
+/// A "prior" lock, i.e. a lock for some now-forgotten reason.
+#[derive(Encode, Decode, Default, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, RuntimeDebug)]
+pub struct PriorLock<BlockNumber, Balance>(BlockNumber, Balance);
+
+impl<BlockNumber: Ord + Copy + Zero, Balance: Ord + Copy + Zero> PriorLock<BlockNumber, Balance> {
+	/// Accumulates an additional lock.
+	pub fn accumulate(&mut self, until: BlockNumber, amount: Balance) {
+		self.0 = self.0.max(until);
+		self.1 = self.1.max(amount);
+	}
+
+	pub fn locked(&self) -> Balance {
+		self.1
+	}
+
+	pub fn rejig(&mut self, now: BlockNumber) {
+		if now >= self.0 {
+			self.0 = Zero::zero();
+			self.1 = Zero::zero();
+		}
+	}
+}
+
+/// An indicator for what an account is doing; it can either be delegating or voting.
+#[derive(Encode, Decode, Clone, Eq, PartialEq, RuntimeDebug)]
+pub enum Voting<Balance, AccountId, BlockNumber> {
+	/// The account is voting directly. `delegations` is the total amount of post-conviction voting
+	/// weight that it controls from those that have delegated to it.
+	Direct {
+		/// The current votes of the account.
+		votes: Vec<(ReferendumIndex, AccountVote<Balance>)>,
+		/// The total amount of delegations that this account has received.
+		delegations: Delegations<Balance>,
+		/// Any pre-existing locks from past voting/delegating activity.
+		prior: PriorLock<BlockNumber, Balance>,
+	},
+	/// The account is delegating `balance` of its balance to a `target` account with `conviction`.
+	Delegating {
+		balance: Balance,
+		target: AccountId,
+		conviction: Conviction,
+		/// The total amount of delegations that this account has received.
+		delegations: Delegations<Balance>,
+		/// Any pre-existing locks from past voting/delegating activity.
+		prior: PriorLock<BlockNumber, Balance>,
+	},
+}
+
+impl<Balance: Default, AccountId, BlockNumber: Zero> Default for Voting<Balance, AccountId, BlockNumber> {
+	fn default() -> Self {
+		Voting::Direct {
+			votes: Vec::new(),
+			delegations: Default::default(),
+			prior: PriorLock(Zero::zero(), Default::default()),
+		}
+	}
+}
+
+impl<
+	Balance: Saturating + Ord + Zero + Copy,
+	BlockNumber: Ord + Copy + Zero,
+	AccountId,
+> Voting<Balance, AccountId, BlockNumber> {
+	pub fn rejig(&mut self, now: BlockNumber) {
+		match self {
+			Voting::Direct { prior, .. } => prior,
+			Voting::Delegating { prior, .. } => prior,
+		}.rejig(now);
+	}
+
+	/// The amount of this account's balance that much currently be locked due to voting.
+	pub fn locked_balance(&self) -> Balance {
+		match self {
+			Voting::Direct { votes, prior, .. } => votes.iter()
+				.map(|i| i.1.balance())
+				.fold(prior.locked(), |a, i| a.max(i)),
+			Voting::Delegating { balance, .. } => *balance,
+		}
+	}
+
+	pub fn set_common(&mut self,
+		delegations: Delegations<Balance>,
+		prior: PriorLock<BlockNumber, Balance>
+	) {
+		let (d, p) = match self {
+			Voting::Direct { ref mut delegations, ref mut prior, .. } => (delegations, prior),
+			Voting::Delegating { ref mut delegations, ref mut prior, .. } => (delegations, prior),
+		};
+		*d = delegations;
+		*p = prior;
+	}
+}