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

use arrow::array::Array;
use arrow::trusted_len::TrustedLen;

use crate::chunked_array::object::{ObjectArray, PolarsObject};

/// An iterator that returns Some(T) or None, that can be used on any ObjectArray
// Note: This implementation is based on std's [Vec]s' [IntoIter].
pub struct ObjectIter<'a, T: PolarsObject> {
    array: &'a ObjectArray<T>,
    current: usize,
    current_end: usize,
}

impl<'a, T: PolarsObject> ObjectIter<'a, T> {
    /// create a new iterator
    pub fn new(array: &'a ObjectArray<T>) -> Self {
        ObjectIter::<T> {
            array,
            current: 0,
            current_end: array.len(),
        }
    }
}

impl<'a, T: PolarsObject> std::iter::Iterator for ObjectIter<'a, T> {
    type Item = Option<&'a T>;

    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        if self.current == self.current_end {
            None
        // SAFETY:
        // Se comment below
        } else if unsafe { self.array.is_null_unchecked(self.current) } {
            self.current += 1;
            Some(None)
        } else {
            let old = self.current;
            self.current += 1;
            // SAFETY:
            // we just checked bounds in `self.current_end == self.current`
            // this is safe on the premise that this struct is initialized with
            // current = array.len()
            // and that current_end is ever only decremented
            unsafe { Some(Some(self.array.value_unchecked(old))) }
        }
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        (
            self.array.len() - self.current,
            Some(self.array.len() - self.current),
        )
    }
}

impl<'a, T: PolarsObject> std::iter::DoubleEndedIterator for ObjectIter<'a, T> {
    fn next_back(&mut self) -> Option<Self::Item> {
        if self.current_end == self.current {
            None
        } else {
            self.current_end -= 1;
            Some(if self.array.is_null(self.current_end) {
                None
            } else {
                // SAFETY:
                // we just checked bounds in `self.current_end == self.current`
                // this is safe on the premise that this struct is initialized with
                // current = array.len()
                // and that current_end is ever only decremented
                unsafe { Some(self.array.value_unchecked(self.current_end)) }
            })
        }
    }
}

/// all arrays have known size.
impl<'a, T: PolarsObject> std::iter::ExactSizeIterator for ObjectIter<'a, T> {}

impl<'a, T: PolarsObject> IntoIterator for &'a ObjectArray<T> {
    type Item = Option<&'a T>;
    type IntoIter = ObjectIter<'a, T>;

    fn into_iter(self) -> Self::IntoIter {
        ObjectIter::<'a, T>::new(self)
    }
}

pub struct OwnedObjectIter<T: PolarsObject> {
    array: ObjectArray<T>,
    current: usize,
    current_end: usize,
}

impl<T: PolarsObject> OwnedObjectIter<T> {
    /// create a new iterator
    pub fn new(array: ObjectArray<T>) -> Self {
        let current_end = array.len();
        OwnedObjectIter::<T> {
            array,
            current: 0,
            current_end,
        }
    }
}

unsafe impl<T: PolarsObject> TrustedLen for OwnedObjectIter<T> {}

impl<T: PolarsObject> ObjectArray<T> {
    pub(crate) fn into_iter_cloned(self) -> OwnedObjectIter<T> {
        OwnedObjectIter::<T>::new(self)
    }
}
impl<T: PolarsObject> std::iter::Iterator for OwnedObjectIter<T> {
    type Item = Option<T>;

    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        if self.current == self.current_end {
            None
        // SAFETY:
        // Se comment below
        } else if unsafe { self.array.is_null_unchecked(self.current) } {
            self.current += 1;
            Some(None)
        } else {
            let old = self.current;
            self.current += 1;
            // SAFETY:
            // we just checked bounds in `self.current_end == self.current`
            // this is safe on the premise that this struct is initialized with
            // current = array.len()
            // and that current_end is ever only decremented
            unsafe { Some(Some(self.array.value_unchecked(old).clone())) }
        }
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        (
            self.array.len() - self.current,
            Some(self.array.len() - self.current),
        )
    }
}