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