content 0.1.0

Trait for content-adressable types
Documentation 
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// Copyright 2015, 2016 Ethcore (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/>.

use std::collections::HashMap;
use std::io::{Result, Read, Write, Error, ErrorKind};

use backend::Backend;
use hash::{Hash32, NewHash, WriteThroughHasher};

impl Backend for HashMap<Hash32, Vec<u8>>
{
	fn store(
		&mut self,
		source: &Fn(&mut Write, &mut Backend) -> Result<()>,
		newhash: &NewHash,
	) -> Result<Hash32> {
		let mut vec = vec![];
		let hash;
		{
			let mut wth = WriteThroughHasher::new(&mut vec, newhash);
			try!(source(&mut wth, self));
			hash = wth.finalize();
		}
		self.insert(hash.clone(), vec);
		Ok(hash)
	}
	fn request(
		&self,
		hash: &Hash32,
		read: &Fn(&mut Read) -> Result<()>,
	) -> Result<()> {
		let vec = try!(self.get(hash)
					   .ok_or(Error::new(ErrorKind::NotFound, "")));
		read(&mut &vec[..])
	}
}