// Copyright 2015, 2016 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/>.

pub trait Forkable {
	fn fork(self, fork_number: usize) -> Self where Self: Sized;
}

pub struct Fork<I> {
	pub iter: I,
	pub fork_number: usize,
}

impl<I> Clone for Fork<I> where I: Iterator + Clone {
	fn clone(&self) -> Self {
		Fork {
			iter: self.iter.clone(),
			fork_number: self.fork_number
		}
	}
}

impl<I> Iterator for Fork<I> where I: Iterator, <I as Iterator>::Item: Forkable {
	type Item = <I as Iterator>::Item;

	#[inline]
	fn next(&mut self) -> Option<Self::Item> {
		self.iter.next().map(|item| item.fork(self.fork_number))
	}
}