1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68
// Copyright 2015-2017 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/>. //! Vector extensions. /// Returns len of prefix shared with elem /// /// ```rust /// extern crate ethcore_util as util; /// use util::vector::SharedPrefix; /// /// fn main () { /// let a = vec![1,2,3,3,5]; /// let b = vec![1,2,3]; /// assert_eq!(a.shared_prefix_len(&b), 3); /// } /// ``` pub trait SharedPrefix<T> { /// Get common prefix length fn shared_prefix_len(&self, elem: &[T]) -> usize; } impl<T> SharedPrefix<T> for [T] where T: Eq { fn shared_prefix_len(&self, elem: &[T]) -> usize { use std::cmp; let len = cmp::min(self.len(), elem.len()); (0..len).take_while(|&i| self[i] == elem[i]).count() } } #[cfg(test)] mod test { use vector::SharedPrefix; #[test] fn test_shared_prefix() { let a = vec![1,2,3,4,5,6]; let b = vec![4,2,3,4,5,6]; assert_eq!(a.shared_prefix_len(&b), 0); } #[test] fn test_shared_prefix2() { let a = vec![1,2,3,3,5]; let b = vec![1,2,3]; assert_eq!(a.shared_prefix_len(&b), 3); } #[test] fn test_shared_prefix3() { let a = vec![1,2,3,4,5,6]; let b = vec![1,2,3,4,5,6]; assert_eq!(a.shared_prefix_len(&b), 6); } }