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// Copyright 2015-2018 Parity Technologies (UK) Ltd.
// This file is part of Parity.

// Parity 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.

// Parity 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 Parity.  If not, see <http://www.gnu.org/licenses/>.

/// Transaction readiness.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Readiness {
    /// The transaction is stale (and should/will be removed from the pool).
    Stale,
    /// The transaction is ready to be included in pending set.
    Ready,
    /// The transaction is not yet ready.
    Future,
}

/// A readiness indicator.
pub trait Ready<T> {
    /// Returns true if transaction is ready to be included in pending block,
    /// given all previous transactions that were ready are already included.
    ///
    /// NOTE: readiness of transactions will be checked according to `Score` ordering,
    /// the implementation should maintain a state of already checked transactions.
    fn is_ready(&mut self, tx: &T) -> Readiness;
}

impl<T, F> Ready<T> for F
where
    F: FnMut(&T) -> Readiness,
{
    fn is_ready(&mut self, tx: &T) -> Readiness {
        (*self)(tx)
    }
}

impl<T, A, B> Ready<T> for (A, B)
where
    A: Ready<T>,
    B: Ready<T>,
{
    fn is_ready(&mut self, tx: &T) -> Readiness {
        match self.0.is_ready(tx) {
            Readiness::Ready => self.1.is_ready(tx),
            r => r,
        }
    }
}