2016-02-01 14:48:38 +01:00
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//! Vector extensions.
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2015-11-29 15:41:29 +01:00
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2015-11-29 18:44:29 +01:00
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/// Returns len of prefix shared with elem
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///
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/// ```rust
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/// extern crate ethcore_util as util;
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/// use util::vector::SharedPrefix;
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///
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/// fn main () {
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/// let a = vec![1,2,3,3,5];
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/// let b = vec![1,2,3];
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/// assert_eq!(a.shared_prefix_len(&b), 3);
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/// }
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/// ```
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pub trait SharedPrefix <T> {
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2016-01-19 17:02:01 +01:00
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/// TODO [debris] Please document me
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2015-11-29 18:44:29 +01:00
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fn shared_prefix_len(&self, elem: &[T]) -> usize;
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}
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impl <T> SharedPrefix<T> for Vec<T> where T: Eq {
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fn shared_prefix_len(&self, elem: &[T]) -> usize {
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use std::cmp;
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let len = cmp::min(self.len(), elem.len());
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(0..len).take_while(|&i| self[i] == elem[i]).count()
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}
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}
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#[cfg(test)]
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mod test {
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use vector::SharedPrefix;
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#[test]
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fn test_shared_prefix() {
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2015-11-30 00:28:03 +01:00
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let a = vec![1,2,3,4,5,6];
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let b = vec![4,2,3,4,5,6];
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assert_eq!(a.shared_prefix_len(&b), 0);
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}
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#[test]
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fn test_shared_prefix2() {
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2015-11-29 18:44:29 +01:00
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let a = vec![1,2,3,3,5];
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let b = vec![1,2,3];
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assert_eq!(a.shared_prefix_len(&b), 3);
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}
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2015-11-30 00:28:03 +01:00
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#[test]
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fn test_shared_prefix3() {
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let a = vec![1,2,3,4,5,6];
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let b = vec![1,2,3,4,5,6];
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assert_eq!(a.shared_prefix_len(&b), 6);
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}
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2015-11-29 15:41:29 +01:00
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}
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