// Copyright 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/>.

use std::ops::Range;

/// Construct a range from an offset to a data length after the offset.
/// Returns None if the end of the range would exceed some maximum offset.
pub fn checked_range(offset: usize, len: usize, max: usize) -> Option<Range<usize>> {
	let end = offset.checked_add(len)?;
	if end <= max {
		Some(offset..end)
	} else {
		None
	}
}