openethereum/util/src/vector.rs

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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/>.
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//! Vector extensions.
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/// 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> {
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/// Get common prefix length
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fn shared_prefix_len(&self, elem: &[T]) -> usize;
}
impl <T> SharedPrefix<T> for Vec<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() {
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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);
}
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}