2020-04-03 05:57:24 +00:00
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use std::collections::HashMap;
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2020-10-16 05:37:48 +00:00
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use std::fmt::Write;
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2020-10-15 06:38:10 +00:00
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2020-04-03 05:57:24 +00:00
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fn levenshtein_distance(s1: &str, s2: &str) -> usize {
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2020-10-16 05:37:48 +00:00
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let mut column: Vec<_> = (0..=s1.len()).collect();
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2020-04-03 05:57:24 +00:00
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for (x, rx) in s2.bytes().enumerate() {
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column[0] = x + 1;
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let mut lastdiag = x;
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for (y, ry) in s1.bytes().enumerate() {
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let olddiag = column[y + 1];
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if rx != ry {
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lastdiag += 1;
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}
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column[y + 1] = (column[y + 1] + 1).min((column[y] + 1).min(lastdiag));
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lastdiag = olddiag;
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}
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}
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column[s1.len()]
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}
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pub fn make_suggestion<'a, I>(prefix: &str, options: I, input: &str) -> Option<String>
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where
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I: Iterator<Item = &'a str>,
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{
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let mut selected = Vec::new();
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let mut distances = HashMap::new();
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for opt in options {
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let distance = levenshtein_distance(input, opt);
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let threshold = (input.len() / 2).max((opt.len() / 2).max(1));
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if distance < threshold {
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selected.push(opt);
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distances.insert(opt, distance);
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}
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}
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if selected.is_empty() {
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return None;
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}
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selected.sort_by(|a, b| distances[a].cmp(&distances[b]));
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2020-10-16 05:52:52 +00:00
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let mut suggestion =
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String::with_capacity(prefix.len() + selected.iter().map(|s| s.len() + 5).sum::<usize>());
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2020-10-16 05:37:48 +00:00
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suggestion.push_str(prefix);
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suggestion.push(' ');
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for (i, s) in selected.iter().enumerate() {
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if i != 0 {
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2020-10-16 06:49:22 +00:00
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suggestion.push_str(", ");
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2020-10-16 05:37:48 +00:00
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}
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write!(suggestion, "\"{}\"", s).unwrap();
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}
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suggestion.push('?');
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Some(suggestion)
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2020-04-03 05:57:24 +00:00
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}
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