pray_core/
cli_suggest.rs

1pub const TOP_LEVEL_COMMANDS: &[&str] = &[
2    "add", "apply", "clean", "confess", "drift", "explain", "fmt", "format", "help", "init",
3    "install", "list", "login", "manifest", "outdated", "package", "plan", "prayer", "publish",
4    "remove", "render", "repo", "serve", "sync", "tree", "trust", "unlock", "update", "upgrade",
5    "vendor", "verify", "version",
6];
7
8pub fn unknown_command_message(command: &str) -> String {
9    let mut message = format!("unknown command: {command}");
10    if let Some(suggestion) = suggest_command(command, TOP_LEVEL_COMMANDS) {
11        message.push_str(&format!("\nDid you mean `{suggestion}`?"));
12    }
13    message
14}
15
16pub fn suggest_command<'a>(input: &str, candidates: &'a [&str]) -> Option<&'a str> {
17    let maximum_distance = if input.chars().count() <= 3 { 1 } else { 2 };
18    candidates
19        .iter()
20        .copied()
21        .filter(|candidate| levenshtein_distance(input, candidate) <= maximum_distance)
22        .min_by_key(|candidate| levenshtein_distance(input, candidate))
23}
24
25fn levenshtein_distance(left: &str, right: &str) -> usize {
26    let left_chars: Vec<char> = left.chars().collect();
27    let right_chars: Vec<char> = right.chars().collect();
28    let left_length = left_chars.len();
29    let right_length = right_chars.len();
30
31    if left_length == 0 {
32        return right_length;
33    }
34    if right_length == 0 {
35        return left_length;
36    }
37
38    let mut previous_row: Vec<usize> = (0..=right_length).collect();
39    let mut current_row = vec![0; right_length + 1];
40
41    for (left_index, left_character) in left_chars.iter().enumerate() {
42        current_row[0] = left_index + 1;
43        for (right_index, right_character) in right_chars.iter().enumerate() {
44            let substitution_cost = if left_character == right_character {
45                0
46            } else {
47                1
48            };
49            current_row[right_index + 1] = (previous_row[right_index + 1] + 1)
50                .min(current_row[right_index] + 1)
51                .min(previous_row[right_index] + substitution_cost);
52        }
53        std::mem::swap(&mut previous_row, &mut current_row);
54    }
55
56    previous_row[right_length]
57}
58
59#[cfg(test)]
60mod tests {
61    use super::{suggest_command, unknown_command_message, TOP_LEVEL_COMMANDS};
62
63    #[test]
64    fn suggests_install_for_common_typo() {
65        assert_eq!(
66            suggest_command("instal", TOP_LEVEL_COMMANDS),
67            Some("install")
68        );
69    }
70
71    #[test]
72    fn unknown_command_includes_suggestion() {
73        let message = unknown_command_message("instal");
74        assert!(message.contains("unknown command: instal"));
75        assert!(message.contains("Did you mean `install`?"));
76    }
77}
pray_core/cli_suggest.rs

pray_core/
cli_suggest.rs
