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// Copyright 2018-2021 Parity Technologies (UK) Ltd. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. use crate::Key; /// A key pointer. /// /// This wraps a base key and provides an interface to mimic pointer arithmetics. /// Mainly used to coordinate keys through static storage structures. #[derive(Debug, Copy, Clone, Eq, PartialEq)] pub struct KeyPtr { /// The underlying offset key. key: Key, /// The last shift performed. last_shift: u64, } impl From<Key> for KeyPtr { #[inline] fn from(key: Key) -> Self { Self { key, last_shift: 0 } } } impl KeyPtr { /// Advances the key pointer by the given amount and returns the old value. #[inline] pub fn advance_by(&mut self, new_shift: u64) -> &Key { let old_shift = core::mem::replace(&mut self.last_shift, new_shift); self.key += old_shift; &self.key } /// Returns the underlying offset key. pub fn key(&self) -> &Key { &self.key } }