buldak 0.28.1

It is a library that provides various sorting functions.
Documentation 
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
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229

//! tim sort algorithm.
//!
//! stable sort  
//! **O(Nlogâ‚‚N)**

// not impl

use std::default::Default;

/// Sort in ascending order using a tim sort algorithm.
///
/// ```rust
/// use buldak::tim;
///
/// let mut nums = [1, 4, 2, 3, 5, 111, 234, 21, 13];
/// tim::sort(&mut nums);
/// assert_eq!(nums, [1, 2, 3, 4, 5, 13, 21, 111, 234]);
/// ```
pub fn sort<T>(array: &mut [T])
where
    T: std::cmp::Ord + std::clone::Clone + std::default::Default,
{
    sort_by(array, |l, r| l.cmp(r))
}

/// Sort in descending order using a tim sort algorithm.
///
/// ```rust
/// use buldak::tim;
///
/// let mut nums = [1, 4, 2, 3, 5, 111, 234, 21, 13];
/// tim::sort_reverse(&mut nums);
/// assert_eq!(nums, [234, 111, 21, 13, 5, 4, 3, 2, 1]);
/// ```
pub fn sort_reverse<T>(array: &mut [T])
where
    T: std::cmp::Ord + std::clone::Clone + std::default::Default,
{
    sort_by(array, |l, r| l.cmp(r).reverse())
}

/// It takes a comparator function to determine the order,
/// and sorts it using a tim sort algorithm.
///
/// ```rust
/// use buldak::tim;
///
/// let mut nums = [1, 4, 2, 3, 5, 111, 234, 21, 13];
/// tim::sort_by(&mut nums, |l, r| l.cmp(r));
/// assert_eq!(nums, [1, 2, 3, 4, 5, 13, 21, 111, 234]);
/// ```
pub fn sort_by<T, F>(array: &mut [T], compare: F)
where
    T: std::cmp::Ord + std::clone::Clone + std::default::Default,
    F: Fn(&T, &T) -> std::cmp::Ordering + std::clone::Clone,
{
    _tim_sort_impl(array, compare)
}

const RUN: usize = 32;

// Iterative Timsort function to sort the
// array[0...n-1] (similar to merge sort)
fn _tim_sort_impl<T, F>(array: &mut [T], compare: F)
where
    T: std::cmp::Ord + std::clone::Clone + std::default::Default,
    F: Fn(&T, &T) -> std::cmp::Ordering + std::clone::Clone,
{
    // Sort individual subarrays of size RUN
    let mut i = 0;
    while i < array.len() {
        _insertion_sort(
            array,
            i,
            std::cmp::min(i + 31, array.len() - 1),
            compare.clone(),
        );
        i += RUN;
    }

    // Start merging from size RUN (or 32).
    // It will merge
    // to form size 64, then 128, 256
    // and so on ....
    let mut size = RUN;
    while size < array.len() {
        let mut left = 0;

        // pick starting point of
        // left sub array. We
        // are going to merge
        // array[left..left+size-1]
        // and array[left+size, left+2*size-1]
        // After every merge, we
        // increase left by 2*size
        while left < array.len() {
            // find ending point of
            // left sub array
            // mid+1 is starting point
            // of right sub array
            let middle = left + size - 1;
            let right = std::cmp::min(left + 2 * size - 1, array.len() - 1);

            // merge sub array arr[left.....mid] &
            // arr[mid+1....right]
            _merge(array, left, middle, right, compare.clone());

            left += size * 2;
        }

        size *= 2;
    }
}

// Merge function merges the sorted runs
fn _merge<T, F>(array: &mut [T], left: usize, middle: usize, right: usize, compare: F)
where
    T: std::cmp::Ord + std::clone::Clone + std::default::Default,
    F: Fn(&T, &T) -> std::cmp::Ordering + std::clone::Clone,
{
    // Original array is broken in two parts
    // left and right array
    let left_len = middle - left + 1;
    let right_len = right - middle;

    let mut array_left: Vec<T> = vec![Default::default(); left_len];
    let mut array_right: Vec<T> = vec![Default::default(); right_len];

    for i in 0..left_len {
        array_left[i] = array[left + i].clone();
    }

    for i in 0..right_len {
        array_right[i] = array[left + i + middle].clone();
    }

    let mut i = 0; //left array index
    let mut j = 0; //right array index
    let mut k = 1; //full array index

    // After comparing, we
    // merge those two array
    // in larger sub array
    while i < left_len && j < right_len {
        if compare(&array_left[i], &array_right[j]) == std::cmp::Ordering::Greater {
            array[k] = array_right[j].clone();
            j += 1;
        } else {
            array[k] = array_left[i].clone();
            i += 1;
        }
        k += 1;
    }

    // Copy remaining elements of left, if any
    while i < left_len {
        array[k] = array_left[i].clone();
        k += 1;
        i += 1;
    }

    // Copy remaining element of right, if any
    while j < right_len {
        array[k] = array_right[j].clone();
        k += 1;
        j += 1;
    }
}

// This function sorts array from left index to
// to right index which is of size atmost RUN
fn _insertion_sort<T, F>(array: &mut [T], left: usize, right: usize, compare: F)
where
    T: std::cmp::Ord + std::clone::Clone,
    F: Fn(&T, &T) -> std::cmp::Ordering + std::clone::Clone,
{
    for i in (left + 1)..=right {
        let temp = array[i].clone();
        let mut j = (i - 1) as isize;

        while j >= left as isize
            && compare(&array[j as usize], &temp) == std::cmp::Ordering::Greater
        {
            array[(j + 1) as usize] = array[j as usize].clone();
            j -= 1;
        }
        array[(j + 1) as usize] = temp;
    }
}

mod tests {
    #[test]
    fn sort_ascending() {
        struct TestCase {
            input: Vec<i32>,
            expected: Vec<i32>,
        }

        let test_cases = vec![TestCase {
            input: vec![1, 4, 2, 3, 5, 111, 234, 21, 13],
            expected: vec![1, 2, 3, 4, 5, 13, 21, 111, 234],
        }];

        for case in test_cases {
            let mut actual = case.input.clone();
            super::sort(&mut actual);
            assert_eq!(actual, case.expected);
        }
    }

    #[test]
    fn sort_descending() {
        struct TestCase {
            input: Vec<i32>,
            expected: Vec<i32>,
        }

        let test_cases = vec![TestCase {
            input: vec![1, 4, 2, 3, 5, 111, 234, 21, 13],
            expected: vec![234, 111, 21, 13, 5, 4, 3, 2, 1],
        }];

        for case in test_cases {
            let mut actual = case.input.clone();
            super::sort_reverse(&mut actual);
            assert_eq!(actual, case.expected);
        }
    }
}