fm84 0.26.2

A synthwave dual-pane TUI file manager
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213

//! Finding text in the viewer and the editor. Both hold their text as lines
//! and place things by (line, character column), so the search works in those
//! terms and leaves turning a match into a selection, a cursor or a scroll to
//! each of them.

/// What Ctrl+F looks for. Smart case, as in less and vim: a term written all
/// in lower case matches either case, and one with a capital in it matches
/// exactly - "readme" finds README, "README" finds only that.
pub struct Needle {
    chars: Vec<char>,
    fold: bool,
}

impl Needle {
    /// None for an empty term, which would match everywhere.
    pub fn new(term: &str) -> Option<Self> {
        if term.is_empty() {
            return None;
        }
        let fold = !term.chars().any(char::is_uppercase);
        let chars = term.chars().map(|c| if fold { fold_char(c) } else { c }).collect();
        Some(Needle { chars, fold })
    }

    /// How many characters it is.
    pub fn len(&self) -> usize {
        self.chars.len()
    }

    /// Every match in `line`, as character ranges, left to right and not
    /// overlapping - so "aa" in "aaaa" is found twice, as an editor would.
    pub fn find_all(&self, line: &str) -> Vec<(usize, usize)> {
        let haystack: Vec<char> = line.chars().map(|c| if self.fold { fold_char(c) } else { c }).collect();
        let length = self.chars.len();
        let mut found = Vec::new();
        let mut index = 0;
        while index + length <= haystack.len() {
            if haystack[index..index + length] == self.chars[..] {
                found.push((index, index + length));
                index += length;
            } else {
                index += 1;
            }
        }
        found
    }
}

/// Lower case one character for one character. A few have a lower case that
/// is two (İ is i and a combining dot); those are left as they are, so that a
/// column counted in the folded line is the same column in the real one.
pub fn fold_char(c: char) -> char {
    let mut lower = c.to_lowercase();
    match (lower.next(), lower.next()) {
        (Some(single), None) => single,
        _ => c,
    }
}

/// A match, in characters, and whether reaching it went round an end of the
/// text to get there.
#[derive(Debug, PartialEq, Eq)]
pub struct Found {
    pub line: usize,
    pub start: usize,
    pub end: usize,
    pub wrapped: bool,
}

/// The match nearest `from` in the direction asked for, going round the end of
/// the text and back to where it started if it has to.
///
/// Forward takes the first match starting at `from` or after it, so searching
/// from the end of one match finds the one after. Backward takes the last
/// match starting before `from`, so searching from the start of one finds the
/// one before. A single match in the whole text is found again either way,
/// marked as having wrapped.
pub fn search(needle: &Needle, count: usize, line_at: impl Fn(usize) -> String, from: (usize, usize), forward: bool) -> Option<Found> {
    if count == 0 {
        return None;
    }
    let (from_line, from_col) = (from.0.min(count - 1), from.1);

    for step in 0..=count {
        let (line, wrapped) = if forward {
            ((from_line + step) % count, from_line + step >= count)
        } else {
            ((from_line + count - step) % count, step > from_line)
        };
        let matches = needle.find_all(&line_at(line));
        // The line the search starts on comes round twice: once for the part
        // ahead of `from`, and once at the end for the part behind it.
        let wanted = |&&(start, _): &&(usize, usize)| match (step, forward) {
            (0, true) => start >= from_col,
            (0, false) => start < from_col,
            (last, true) if last == count => start < from_col,
            (last, false) if last == count => start >= from_col,
            _ => true,
        };
        let hit = if forward { matches.iter().find(wanted) } else { matches.iter().rev().find(wanted) };
        if let Some(&(start, end)) = hit {
            return Some(Found { line, start, end, wrapped });
        }
    }
    None
}

#[cfg(test)]
mod tests {
    use super::*;

    fn lines(text: &'static str) -> (usize, impl Fn(usize) -> String) {
        let lines: Vec<&str> = text.lines().collect();
        (lines.len(), move |index| lines[index].to_string())
    }

    #[test]
    fn lower_case_finds_either_case_and_a_capital_finds_only_itself() {
        let needle = Needle::new("readme").unwrap();
        assert_eq!(needle.find_all("README and readme"), [(0, 6), (11, 17)]);
        let needle = Needle::new("README").unwrap();
        assert_eq!(needle.find_all("README and readme"), [(0, 6)]);
        assert!(Needle::new("").is_none());
    }

    #[test]
    fn columns_are_characters_not_bytes() {
        let needle = Needle::new("fé").unwrap();
        assert_eq!(needle.find_all("café fé"), [(2, 4), (5, 7)]);
        // A letter whose lower case is two characters does not shift the
        // columns after it.
        let needle = Needle::new("x").unwrap();
        assert_eq!(needle.find_all("İx"), [(1, 2)]);
    }

    #[test]
    fn forward_goes_on_from_the_end_of_a_match_and_wraps() {
        let (count, line_at) = lines("one two\ntwo\nthree two");
        let needle = Needle::new("two").unwrap();

        let first = search(&needle, count, &line_at, (0, 0), true).unwrap();
        assert_eq!(first, Found { line: 0, start: 4, end: 7, wrapped: false });
        let second = search(&needle, count, &line_at, (first.line, first.end), true).unwrap();
        assert_eq!(second, Found { line: 1, start: 0, end: 3, wrapped: false });
        let third = search(&needle, count, &line_at, (second.line, second.end), true).unwrap();
        assert_eq!(third, Found { line: 2, start: 6, end: 9, wrapped: false });
        let round = search(&needle, count, &line_at, (third.line, third.end), true).unwrap();
        assert_eq!(round, Found { line: 0, start: 4, end: 7, wrapped: true });
    }

    #[test]
    fn backward_goes_on_from_the_start_of_a_match_and_wraps() {
        let (count, line_at) = lines("one two\ntwo\nthree two");
        let needle = Needle::new("two").unwrap();

        let before = search(&needle, count, &line_at, (1, 0), false).unwrap();
        assert_eq!(before, Found { line: 0, start: 4, end: 7, wrapped: false });
        let round = search(&needle, count, &line_at, (before.line, before.start), false).unwrap();
        assert_eq!(round, Found { line: 2, start: 6, end: 9, wrapped: true });
    }

    #[test]
    fn a_lone_match_is_found_again_and_none_is_none() {
        let (count, line_at) = lines("a\nneedle here\nb");
        let needle = Needle::new("needle").unwrap();
        let only = search(&needle, count, &line_at, (1, 6), true).unwrap();
        assert_eq!(only, Found { line: 1, start: 0, end: 6, wrapped: true });
        let only = search(&needle, count, &line_at, (1, 0), false).unwrap();
        assert_eq!(only, Found { line: 1, start: 0, end: 6, wrapped: true });

        let missing = Needle::new("absent").unwrap();
        assert_eq!(search(&missing, count, &line_at, (0, 0), true), None);
        assert_eq!(search(&missing, 0, |_| String::new(), (0, 0), true), None);
    }

    #[test]
    fn matches_do_not_overlap() {
        let needle = Needle::new("aa").unwrap();
        assert_eq!(needle.find_all("aaaaa"), [(0, 2), (2, 4)]);
        assert_eq!(needle.len(), 2);
    }

    #[test]
    fn a_letter_folds_to_one_lower_case_letter_or_stays() {
        assert_eq!(fold_char('Ä'), 'ä');
        assert_eq!(fold_char('Ж'), 'ж');
        assert_eq!(fold_char('7'), '7');
        // Its lower case is two characters.
        assert_eq!(fold_char('İ'), 'İ');
    }

    #[test]
    fn a_start_past_the_last_line_searches_from_the_last() {
        let (count, line_at) = lines(
            "two
one two",
        );
        let needle = Needle::new("two").unwrap();
        let found = search(&needle, count, &line_at, (9, 0), true).unwrap();
        assert_eq!(found, Found { line: 1, start: 4, end: 7, wrapped: false });
    }

    #[test]
    fn backward_from_the_middle_of_a_line_finds_what_is_before_it_there() {
        let (count, line_at) = lines(
            "x
two and two",
        );
        let needle = Needle::new("two").unwrap();
        let found = search(&needle, count, &line_at, (1, 8), false).unwrap();
        assert_eq!(found, Found { line: 1, start: 0, end: 3, wrapped: false });
    }
}