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

#![warn(clippy::all, clippy::pedantic, clippy::nursery)]

use unicode_segmentation::UnicodeSegmentation;

#[must_use]
pub fn take_last(word: &str) -> String {
    let s = String::from(word);
    // check last
    let last = s.graphemes(true).last();
    String::from(match last {
        Some(letter) => letter,
        None => "",
    })
}

#[must_use]
pub fn take_lasts(word: &str, n: usize) -> String {
    // chars
    let chars = word.graphemes(true).collect::<Vec<&str>>();
    // length of chars
    let len = chars.len();
    // skip "n" and return this tail
    let to_skip = if len >= n { len - n } else { 0 };
    chars
        .iter()
        .map(AsRef::as_ref)
        .skip(to_skip)
        .collect::<Vec<&str>>()
        .join("")
}

#[must_use]
pub fn drop_last(word: &str) -> String {
    drop_lasts(word, 1)
}

#[must_use]
pub fn drop_lasts(word: &str, n: usize) -> String {
    // chars
    let chars = word.graphemes(true).collect::<Vec<&str>>();
    // length of chars
    let len = chars.len();

    // take "n" and return this head
    let to_skip = if len >= n { len - n } else { 0 };
    chars
        .iter()
        .map(AsRef::as_ref)
        .take(to_skip)
        .collect::<Vec<&str>>()
        .join("")
}

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

    #[test]
    fn take_last_works() {
        assert_eq!(take_last("tests"), "s");
        assert_eq!(take_last("xârâcùù"), "ù");
        assert_eq!(take_last("a"), "a");
        assert_eq!(take_last(""), "");
    }

    #[test]
    fn take_lasts_works() {
        assert_eq!(take_lasts("tests", 0), "");
        assert_eq!(take_lasts("xârâcùù", 0), "");
        assert_eq!(take_lasts("a", 0), "");
        assert_eq!(take_lasts("", 0), "");

        assert_eq!(take_lasts("tests", 1), "s");
        assert_eq!(take_lasts("xârâcùù", 1), "ù");
        assert_eq!(take_lasts("a", 1), "a");
        assert_eq!(take_lasts("", 1), "");

        assert_eq!(take_lasts("tests", 2), "ts");
        assert_eq!(take_lasts("xârâcùù", 2), "ùù");
        assert_eq!(take_lasts("a", 2), "a");
        assert_eq!(take_lasts("", 2), "");

        assert_eq!(take_lasts("constitution", 10), "nstitution");
        assert_eq!(take_lasts("xârâcùù", 10), "xârâcùù");
        assert_eq!(take_lasts("a", 10), "a");
        assert_eq!(take_lasts("", 10), "");
    }

    #[test]
    fn drop_last_works() {
        assert_eq!(drop_last("tests"), "test");
        assert_eq!(drop_last("xârâcùù"), "xârâcù");
        assert_eq!(drop_last("a"), "");
        assert_eq!(drop_last(""), "");
    }

    #[test]
    fn drop_lasts_works() {
        assert_eq!(drop_lasts("tests", 0), "tests");
        assert_eq!(drop_lasts("xârâcùù", 0), "xârâcùù");
        assert_eq!(drop_lasts("a", 0), "a");
        assert_eq!(drop_lasts("", 0), "");

        assert_eq!(drop_lasts("tests", 1), "test");
        assert_eq!(drop_lasts("xârâcùù", 1), "xârâcù");
        assert_eq!(drop_lasts("a", 1), "");
        assert_eq!(drop_lasts("", 1), "");

        assert_eq!(drop_lasts("tests", 2), "tes");
        assert_eq!(drop_lasts("xârâcùù", 2), "xârâc");
        assert_eq!(drop_lasts("a", 2), "");
        assert_eq!(drop_lasts("", 2), "");

        assert_eq!(drop_lasts("constitution", 10), "co");
        assert_eq!(drop_lasts("xârâcùù", 10), "");
        assert_eq!(drop_lasts("a", 10), "");
        assert_eq!(drop_lasts("", 10), "");
    }
}