generic_array/
functional.rs

1//! Functional programming with generic sequences
2//!
3//! Please see `tests/generics.rs` for examples of how to best use these in your generic functions.
4
5use super::ArrayLength;
6use core::iter::FromIterator;
7
8use crate::sequence::*;
9
10/// Defines the relationship between one generic sequence and another,
11/// for operations such as `map` and `zip`.
12pub unsafe trait MappedGenericSequence<T, U>: GenericSequence<T>
13where
14    Self::Length: ArrayLength<U>,
15{
16    /// Mapped sequence type
17    type Mapped: GenericSequence<U, Length = Self::Length>;
18}
19
20unsafe impl<'a, T, U, S: MappedGenericSequence<T, U>> MappedGenericSequence<T, U> for &'a S
21where
22    &'a S: GenericSequence<T>,
23    S: GenericSequence<T, Length = <&'a S as GenericSequence<T>>::Length>,
24    <S as GenericSequence<T>>::Length: ArrayLength<U>,
25{
26    type Mapped = <S as MappedGenericSequence<T, U>>::Mapped;
27}
28
29unsafe impl<'a, T, U, S: MappedGenericSequence<T, U>> MappedGenericSequence<T, U> for &'a mut S
30where
31    &'a mut S: GenericSequence<T>,
32    S: GenericSequence<T, Length = <&'a mut S as GenericSequence<T>>::Length>,
33    <S as GenericSequence<T>>::Length: ArrayLength<U>,
34{
35    type Mapped = <S as MappedGenericSequence<T, U>>::Mapped;
36}
37
38/// Accessor type for a mapped generic sequence
39pub type MappedSequence<S, T, U> =
40    <<S as MappedGenericSequence<T, U>>::Mapped as GenericSequence<U>>::Sequence;
41
42/// Defines functional programming methods for generic sequences
43pub unsafe trait FunctionalSequence<T>: GenericSequence<T> {
44    /// Maps a `GenericSequence` to another `GenericSequence`.
45    ///
46    /// If the mapping function panics, any already initialized elements in the new sequence
47    /// will be dropped, AND any unused elements in the source sequence will also be dropped.
48    fn map<U, F>(self, f: F) -> MappedSequence<Self, T, U>
49    where
50        Self: MappedGenericSequence<T, U>,
51        Self::Length: ArrayLength<U>,
52        F: FnMut(Self::Item) -> U,
53    {
54        FromIterator::from_iter(self.into_iter().map(f))
55    }
56
57    /// Combines two `GenericSequence` instances and iterates through both of them,
58    /// initializing a new `GenericSequence` with the result of the zipped mapping function.
59    ///
60    /// If the mapping function panics, any already initialized elements in the new sequence
61    /// will be dropped, AND any unused elements in the source sequences will also be dropped.
62    #[inline]
63    fn zip<B, Rhs, U, F>(self, rhs: Rhs, f: F) -> MappedSequence<Self, T, U>
64    where
65        Self: MappedGenericSequence<T, U>,
66        Rhs: MappedGenericSequence<B, U, Mapped = MappedSequence<Self, T, U>>,
67        Self::Length: ArrayLength<B> + ArrayLength<U>,
68        Rhs: GenericSequence<B, Length = Self::Length>,
69        F: FnMut(Self::Item, Rhs::Item) -> U,
70    {
71        rhs.inverted_zip2(self, f)
72    }
73
74    /// Folds (or reduces) a sequence of data into a single value.
75    ///
76    /// If the fold function panics, any unused elements will be dropped.
77    fn fold<U, F>(self, init: U, f: F) -> U
78    where
79        F: FnMut(U, Self::Item) -> U,
80    {
81        self.into_iter().fold(init, f)
82    }
83}
84
85unsafe impl<'a, T, S: GenericSequence<T>> FunctionalSequence<T> for &'a S
86where
87    &'a S: GenericSequence<T>,
88{
89}
90
91unsafe impl<'a, T, S: GenericSequence<T>> FunctionalSequence<T> for &'a mut S
92where
93    &'a mut S: GenericSequence<T>,
94{
95}
generic_array/functional.rs

generic_array/
functional.rs
