add _head and _tail traversals
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3 changed files with 226 additions and 0 deletions
101
src/traversals/head.rs
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101
src/traversals/head.rs
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@ -0,0 +1,101 @@
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use crate::traversals::{Traversal, TraversalOver, TraversalTraverse};
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#[derive(Clone, Copy)]
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pub struct HeadInner;
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#[allow(non_upper_case_globals)]
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pub const _head: Traversal<HeadInner> = Traversal(HeadInner);
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macro_rules! make_tuples {
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(( $( $v:ident ),* ), ( $( $t:ident ),* ) ) => {
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impl< $($t,)* > TraversalTraverse<( $($t,)* )> for HeadInner {
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type Field = T;
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fn traverse(&self, ( head, $($v,)* ): ($($t,)*)) -> Vec<Self::Field> {
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vec![head]
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}
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}
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impl< $($t,)* > TraversalOver<( $($t,)* )> for HeadInner {
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fn over<F>(
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&self,
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(head, $($v,)*): ($($t,)*),
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mut f: F
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) -> ( $($t,)* )
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where
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F: FnMut(Self::Field) -> Self::Field
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{
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( f(head), $($v,)* )
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}
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}
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impl<'a, $($t,)* > TraversalTraverse<&'a ( $($t,)* )> for HeadInner {
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type Field = &'a T;
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fn traverse(&self, (head, $($v,)* ): &'a ($($t,)*)) -> Vec<Self::Field> {
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vec![ head ]
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}
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}
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impl<'a, $($t,)* > TraversalTraverse<&'a mut ( $($t,)* )> for HeadInner {
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type Field = &'a mut T;
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fn traverse(&self, (head, $($v,)* ): &'a mut ($($t,)*)) -> Vec<Self::Field> {
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vec![ head ]
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}
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}
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};
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}
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make_tuples!((), (T));
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make_tuples!((_u), (T, U));
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make_tuples!((_u, _v), (T, U, V));
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make_tuples!((_u, _v, _w), (T, U, V, W));
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make_tuples!((_u, _v, _w, _x), (T, U, V, W, X));
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make_tuples!((_u, _v, _w, _x, _y), (T, U, V, W, X, Y));
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make_tuples!((_u, _v, _w, _x, _y, _z), (T, U, V, W, X, Y, Z));
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macro_rules! make_arrays {
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($n:expr, [$( $v:ident ),*]) => {
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impl<T> TraversalTraverse<[T; $n]> for HeadInner {
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type Field = T;
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fn traverse(&self, [ head, $($v,)* ]: [T; $n]) -> Vec<Self::Field> {
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vec![head]
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}
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}
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impl<T> TraversalOver<[T; $n]> for HeadInner {
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fn over<F>(
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&self,
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[ head, $($v,)* ]: [T; $n],
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mut fun: F
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) -> [T; $n]
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where
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F: FnMut(Self::Field) -> Self::Field
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{
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[fun(head), $(($v),)*]
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}
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}
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impl<'a, T> TraversalTraverse<&'a [T; $n]> for HeadInner {
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type Field = &'a T;
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fn traverse(&self, [head, $($v,)* ]: &'a [T; $n]) -> Vec<Self::Field> {
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vec![head]
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}
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}
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impl<'a, T> TraversalTraverse<&'a mut [T; $n]> for HeadInner {
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type Field = &'a mut T;
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fn traverse(&self, [head, $($v,)* ]: &'a mut [T; $n]) -> Vec<Self::Field> {
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vec![head]
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}
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}
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};
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}
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make_arrays!(1, []);
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make_arrays!(2, [_a]);
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make_arrays!(3, [_a, _b]);
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make_arrays!(4, [_a, _b, _c]);
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make_arrays!(5, [_a, _b, _c, _d]);
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make_arrays!(6, [_a, _b, _c, _d, _e]);
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make_arrays!(7, [_a, _b, _c, _d, _e, _g]);
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@ -4,6 +4,11 @@ pub use both::both;
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mod each;
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pub use each::each;
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mod head;
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pub use head::_head;
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mod tail;
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pub use tail::_tail;
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use crate::{
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lenses::{Lens, LensOver, LensView},
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prisms::{Prism, PrismPreview},
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@ -154,4 +159,26 @@ mod tests {
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let res = each(array, |v| v + 1);
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assert_eq!(res, [2, 3, 4, 5]);
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}
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#[test]
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fn traverse_head_works_on_arrays() {
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let array = [1, 2, 3, 4];
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let res = _head(array);
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assert_eq!(res, vec![1,]);
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let res = _head(array, |v| v + 1);
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assert_eq!(res, [2, 2, 3, 4,]);
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}
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#[test]
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fn traverse_tail_works_on_arrays() {
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let array = [1, 2, 3, 4];
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let res = _tail(array);
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assert_eq!(res, vec![2, 3, 4]);
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let res = _tail(array, |v| v + 1);
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assert_eq!(res, [1, 3, 4, 5]);
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}
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}
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98
src/traversals/tail.rs
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98
src/traversals/tail.rs
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@ -0,0 +1,98 @@
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use crate::traversals::{Traversal, TraversalOver, TraversalTraverse};
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#[derive(Clone, Copy)]
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pub struct TailInner;
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#[allow(non_upper_case_globals)]
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pub const _tail: Traversal<TailInner> = Traversal(TailInner);
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macro_rules! make_tuples {
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(( $( $v:ident ),* ), ( $( $t:ident ),* ) ) => {
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impl<T> TraversalTraverse<( $($t,)* )> for TailInner {
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type Field = T;
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fn traverse(&self, ( _, $($v,)* ): ($($t,)*)) -> Vec<Self::Field> {
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vec![$($v,)*]
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}
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}
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impl<T> TraversalOver<( $($t,)* )> for TailInner {
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fn over<F>(
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&self,
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(head, $($v,)*): ($($t,)*),
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mut fun: F
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) -> ( $($t,)* )
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where
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F: FnMut(Self::Field) -> Self::Field
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{
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(head, $( fun($v) ,)*)
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}
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}
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impl<'a, T> TraversalTraverse<&'a ( $($t,)* )> for TailInner {
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type Field = &'a T;
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fn traverse(&self, (_, $($v,)* ): &'a ($($t,)*)) -> Vec<Self::Field> {
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vec![ $($v,)* ]
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}
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}
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impl<'a, T> TraversalTraverse<&'a mut ( $($t,)* )> for TailInner {
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type Field = &'a mut T;
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fn traverse(&self, (_, $($v,)* ): &'a mut ($($t,)*)) -> Vec<Self::Field> {
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vec![ $($v,)* ]
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}
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}
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};
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}
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make_tuples!((_u), (T, T));
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make_tuples!((_u, _v), (T, T, T));
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make_tuples!((_u, _v, _w), (T, T, T, T));
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make_tuples!((_u, _v, _w, _x), (T, T, T, T, T));
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make_tuples!((_u, _v, _w, _x, _y), (T, T, T, T, T, T));
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make_tuples!((_u, _v, _w, _x, _y, _z), (T, T, T, T, T, T, T));
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macro_rules! make_arrays {
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($n:expr, [$( $v:ident ),*]) => {
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impl<T> TraversalTraverse<[T; $n]> for TailInner {
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type Field = T;
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fn traverse(&self, [ _, $($v,)* ]: [T; $n]) -> Vec<Self::Field> {
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vec![$($v,)*]
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}
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}
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impl<T> TraversalOver<[T; $n]> for TailInner {
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fn over<F>(
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&self,
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[ head, $($v,)* ]: [T; $n],
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mut fun: F
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) -> [T; $n]
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where
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F: FnMut(Self::Field) -> Self::Field
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{
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[head, $(fun($v),)*]
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}
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}
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impl<'a, T> TraversalTraverse<&'a [T; $n]> for TailInner {
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type Field = &'a T;
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fn traverse(&self, [_, $($v,)* ]: &'a [T; $n]) -> Vec<Self::Field> {
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vec![$($v,)*]
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}
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}
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impl<'a, T> TraversalTraverse<&'a mut [T; $n]> for TailInner {
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type Field = &'a mut T;
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fn traverse(&self, [_, $($v,)* ]: &'a mut [T; $n]) -> Vec<Self::Field> {
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vec![$($v,)*]
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}
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}
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};
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}
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make_arrays!(2, [_a]);
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make_arrays!(3, [_a, _b]);
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make_arrays!(4, [_a, _b, _c]);
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make_arrays!(5, [_a, _b, _c, _d]);
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make_arrays!(6, [_a, _b, _c, _d, _e]);
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make_arrays!(7, [_a, _b, _c, _d, _e, _g]);
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