konst_kernel/into_iter/
slice_into_iter.rs

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
use crate::into_iter::{ConstIntoIter, IntoIterWrapper, IsIteratorKind, IsStdKind};

use core::mem::ManuallyDrop;

impl<'a, T, const N: usize> ConstIntoIter for &'a [T; N] {
    type Kind = IsStdKind;
    type IntoIter = Iter<'a, T>;
    type Item = &'a T;
}

impl<'a, T, const N: usize> ConstIntoIter for &&'a [T; N] {
    type Kind = IsStdKind;
    type IntoIter = Iter<'a, T>;
    type Item = &'a T;
}

impl<'a, T, const N: usize> IntoIterWrapper<&'a [T; N], IsStdKind> {
    pub const fn const_into_iter(self) -> Iter<'a, T> {
        Iter {
            slice: ManuallyDrop::into_inner(self.iter) as &[T],
        }
    }
}
impl<'a, T, const N: usize> IntoIterWrapper<&&'a [T; N], IsStdKind> {
    pub const fn const_into_iter(self) -> Iter<'a, T> {
        Iter {
            slice: (*ManuallyDrop::into_inner(self.iter)) as &[T],
        }
    }
}

impl<'a, T> ConstIntoIter for &'a [T] {
    type Kind = IsStdKind;
    type IntoIter = Iter<'a, T>;
    type Item = &'a T;
}

impl<'a, T> IntoIterWrapper<&'a [T], IsStdKind> {
    pub const fn const_into_iter(self) -> Iter<'a, T> {
        Iter {
            slice: ManuallyDrop::into_inner(self.iter),
        }
    }
}

impl<'a, T> ConstIntoIter for &&'a [T] {
    type Kind = IsStdKind;
    type IntoIter = Iter<'a, T>;
    type Item = &'a T;
}

impl<'a, T> IntoIterWrapper<&&'a [T], IsStdKind> {
    // clippy suggests a change that doesn't compile
    #[allow(clippy::explicit_auto_deref)]
    pub const fn const_into_iter(self) -> Iter<'a, T> {
        Iter {
            slice: *ManuallyDrop::into_inner(self.iter),
        }
    }
}

pub const fn iter<T>(slice: &[T]) -> Iter<'_, T> {
    Iter { slice }
}

macro_rules! iter_shared {
    (is_forward = $is_forward:ident) => {
        iterator_shared! {
            is_forward = $is_forward,
            item = &'a T,
            iter_forward = Iter<'a, T>,
            iter_reversed = IterRev<'a, T>,
            next(self) {
                if let [elem, rem @ ..] = self.slice {
                    self.slice = rem;
                    Some((elem, self))
                } else {
                    None
                }
            },
            next_back {
                if let [rem @ .., elem] = self.slice {
                    self.slice = rem;
                    Some((elem, self))
                } else {
                    None
                }
            },
            fields = {slice},
        }

        /// Accesses the remaining slice.
        pub const fn as_slice(&self) -> &'a [T] {
            self.slice
        }
    };
}

pub struct Iter<'a, T> {
    slice: &'a [T],
}
impl<'a, T> ConstIntoIter for Iter<'a, T> {
    type Kind = IsIteratorKind;
    type IntoIter = Self;
    type Item = &'a T;
}

pub struct IterRev<'a, T> {
    slice: &'a [T],
}
impl<'a, T> ConstIntoIter for IterRev<'a, T> {
    type Kind = IsIteratorKind;
    type IntoIter = Self;
    type Item = &'a T;
}

impl<'a, T> Iter<'a, T> {
    iter_shared! {is_forward = true}
}

impl<'a, T> IterRev<'a, T> {
    iter_shared! {is_forward = false}
}

pub use copied::{iter_copied, IterCopied, IterCopiedRev};

mod copied {
    use super::*;

    pub const fn iter_copied<T: Copy>(slice: &[T]) -> IterCopied<'_, T> {
        IterCopied { slice }
    }

    macro_rules! iter_copied_shared {
        (is_forward = $is_forward:ident) => {
            iterator_shared! {
                is_forward = $is_forward,
                item = T,
                iter_forward = IterCopied<'a, T>,
                iter_reversed = IterCopiedRev<'a, T>,
                next(self) {
                    if let [elem, rem @ ..] = self.slice {
                        self.slice = rem;
                        Some((*elem, self))
                    } else {
                        None
                    }
                },
                next_back {
                    if let [rem @ .., elem] = self.slice {
                        self.slice = rem;
                        Some((*elem, self))
                    } else {
                        None
                    }
                },
                fields = {slice},
            }

            /// Accesses the remaining slice.
            pub const fn as_slice(&self) -> &'a [T] {
                self.slice
            }
        };
    }

    pub struct IterCopied<'a, T> {
        slice: &'a [T],
    }
    impl<'a, T> ConstIntoIter for IterCopied<'a, T> {
        type Kind = IsIteratorKind;
        type IntoIter = Self;
        type Item = T;
    }

    pub struct IterCopiedRev<'a, T> {
        slice: &'a [T],
    }
    impl<'a, T> ConstIntoIter for IterCopiedRev<'a, T> {
        type Kind = IsIteratorKind;
        type IntoIter = Self;
        type Item = T;
    }

    impl<'a, T: Copy> IterCopied<'a, T> {
        iter_copied_shared! {is_forward = true}
    }

    impl<'a, T: Copy> IterCopiedRev<'a, T> {
        iter_copied_shared! {is_forward = false}
    }
}