64 lines
1.9 KiB
Rust
64 lines
1.9 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use std::cmp;
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pub fn lev_distance(me: &str, t: &str) -> uint {
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if me.is_empty() { return t.chars().count(); }
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if t.is_empty() { return me.chars().count(); }
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let mut dcol: Vec<_> = (0..t.len() + 1).collect();
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let mut t_last = 0;
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for (i, sc) in me.chars().enumerate() {
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let mut current = i;
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dcol[0] = current + 1;
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for (j, tc) in t.chars().enumerate() {
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let next = dcol[j + 1];
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if sc == tc {
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dcol[j + 1] = current;
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} else {
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dcol[j + 1] = cmp::min(current, next);
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dcol[j + 1] = cmp::min(dcol[j + 1], dcol[j]) + 1;
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}
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current = next;
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t_last = j;
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}
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}
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dcol[t_last + 1]
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}
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#[test]
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fn test_lev_distance() {
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use std::char::{ from_u32, MAX };
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// Test bytelength agnosticity
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for c in (0u32..MAX as u32)
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.filter_map(|i| from_u32(i))
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.map(|i| i.to_string()) {
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assert_eq!(lev_distance(&c[..], &c[..]), 0);
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}
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let a = "\nMäry häd ä little lämb\n\nLittle lämb\n";
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let b = "\nMary häd ä little lämb\n\nLittle lämb\n";
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let c = "Mary häd ä little lämb\n\nLittle lämb\n";
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assert_eq!(lev_distance(a, b), 1);
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assert_eq!(lev_distance(b, a), 1);
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assert_eq!(lev_distance(a, c), 2);
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assert_eq!(lev_distance(c, a), 2);
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assert_eq!(lev_distance(b, c), 1);
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assert_eq!(lev_distance(c, b), 1);
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}
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