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107 lines
3.3 KiB
Rust
107 lines
3.3 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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use std::cmp::{Ord, Eq};
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pub trait BinarySearchMethods<'self, T: Ord + Eq> {
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fn binary_search(&self, key: &T) -> Option<&'self T>;
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fn binary_search_index(&self, key: &T) -> Option<uint>;
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}
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impl<'self, T: Ord + Eq> BinarySearchMethods<'self, T> for &'self [T] {
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fn binary_search(&self, key: &T) -> Option<&'self T> {
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self.binary_search_index(key).map(|i| &self[i])
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}
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fn binary_search_index(&self, key: &T) -> Option<uint> {
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if self.len() == 0 {
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return None;
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}
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let mut low : int = 0;
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let mut high : int = (self.len() as int) - 1;
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while (low <= high) {
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// http://googleresearch.blogspot.com/2006/06/extra-extra-read-all-about-it-nearly.html
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let mid : int = (((low as uint) + (high as uint)) >> 1) as int;
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let midv = &self[mid];
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if (midv < key) {
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low = mid + 1;
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} else if (midv > key) {
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high = mid - 1;
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} else {
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return Some(mid as uint);
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}
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}
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return None;
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}
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}
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fn test_find_all_elems<T: Eq + Ord>(arr: &[T]) {
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let mut i = 0;
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while i < arr.len() {
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assert!(test_match(&arr[i], arr.binary_search(&arr[i])));
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i += 1;
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}
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}
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fn test_miss_all_elems<T: Eq + Ord>(arr: &[T], misses: &[T]) {
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let mut i = 0;
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while i < misses.len() {
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let res = arr.binary_search(&misses[i]);
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debug!("{:?} == {:?} ?", misses[i], res);
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assert!(!test_match(&misses[i], arr.binary_search(&misses[i])));
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i += 1;
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}
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}
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fn test_match<T: Eq>(b: &T, a: Option<&T>) -> bool {
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match a {
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None => false,
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Some(t) => t == b
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}
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}
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pub fn zip_copies<A: Clone, B: Clone>(avec: &[A], bvec: &[B]) -> ~[(A,B)] {
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avec.iter().map(|x| x.clone())
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.zip(bvec.iter().map(|x| x.clone()))
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.collect()
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}
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fn should_find_all_elements() {
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#[test];
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let arr_odd = [1, 2, 4, 6, 7, 8, 9];
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let arr_even = [1, 2, 5, 6, 7, 8, 9, 42];
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let arr_double = [1, 1, 2, 2, 6, 8, 22];
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let arr_one = [234986325];
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let arr_two = [3044, 8393];
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let arr_three = [12, 23, 34];
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test_find_all_elems(arr_odd);
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test_find_all_elems(arr_even);
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test_find_all_elems(arr_double);
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test_find_all_elems(arr_one);
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test_find_all_elems(arr_two);
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test_find_all_elems(arr_three);
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}
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fn should_not_find_missing_elements() {
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#[test];
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let arr_odd = [1, 2, 4, 6, 7, 8, 9];
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let arr_even = [1, 2, 5, 6, 7, 8, 9, 42];
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let arr_double = [1, 1, 2, 2, 6, 8, 22];
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let arr_one = [234986325];
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let arr_two = [3044, 8393];
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let arr_three = [12, 23, 34];
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test_miss_all_elems(arr_odd, [-22, 0, 3, 5, 34938, 10, 11, 12]);
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test_miss_all_elems(arr_even, [-1, 0, 3, 34938, 10, 11, 12]);
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test_miss_all_elems(arr_double, [-1, 0, 3, 4, 34938, 10, 11, 12, 234, 234, 33]);
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test_miss_all_elems(arr_one, [-1, 0, 3, 34938, 10, 11, 12, 234, 234, 33]);
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test_miss_all_elems(arr_two, [-1, 0, 3, 34938, 10, 11, 12, 234, 234, 33]);
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test_miss_all_elems(arr_three, [-2, 0, 1, 2, 3, 34938, 10, 11, 234, 234, 33]);
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}
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