coreylowman · coreylowman · Sep 18, 2022 · Sep 8, 2022 · Sep 8, 2022 · Sep 8, 2022
diff --git a/src/devices/select.rs b/src/devices/select.rs
@@ -1,107 +1,140 @@
 //! Implementations of selecting either 1 or Z elements from an axis of an nd array.
 //!
 //! # Implementation Details
-//! There are three cases to handle:
+//! There are four cases to handle:
 //!
-//! ## Selecting 1 element from the 0th axis
+//! ## Selecting 1 element from the 0th axis [select_modes::Index]
 //!
 //! Just index into input using the single index and assign to output.
 //!
-//! ## Selecting Z elements from the 0th axis
+//! ## Selecting Z elements from the 0th axis [select_modes::Index]
 //!
 //! Just index into input for each index and assing to `output[z]`
 //!
-//! ## Selecting either 1 or Z elements from a non-zero axis
+//! ## Selecting either 1 or Z elements from a non-zero axis [select_modes::Recurse]
 //!
 //! Then all three arrays with have the same dimension as the 0th axis.
 //! Do a for loop over the 0th axis and recurse!
+//!
+//! ## Broadcasted select [select_modes::Broadcast]
+//!
+//! In this case only the indices & output are indexed. The input is broadcasted by
+//! not indexing into it.
 
 use super::{Cpu, ForEachElement};
 use crate::arrays::CountElements;
 
-/// Select values from `T` using `Indices` and producing `R` along a single `AXIS`.
-pub trait SelectAlongAxis<T: CountElements, Indices, R: CountElements, const AXIS: isize> {
+/// Used to disambiguate trait implementations. Callees
+/// must specify what kind of selection is occurring.
+pub(crate) mod select_modes {
+    use std::marker::PhantomData;
+
+    /// Select the current axis.
+    pub struct Index;
+
+    /// Recurse the current axis.
+    pub struct Recurse<M>(PhantomData<*const M>);
+
+    /// Broadcast the current axis of input and recurse the indices.
+    pub struct Broadcast<M>(PhantomData<*const M>);
+}
+
+use select_modes::{Broadcast, Index, Recurse};
+
+pub(crate) type SelectAx0 = select_modes::Index;
+pub(crate) type SelectAx1 = select_modes::Recurse<SelectAx0>;
+pub(crate) type SelectAx2 = select_modes::Recurse<SelectAx1>;
+pub(crate) type SelectAx3 = select_modes::Recurse<SelectAx2>;
+pub(crate) type BSelectAx1 = select_modes::Broadcast<SelectAx0>;
+
+/// Select values from `T` using indices `I`. `Mode` is used to disambiguate the impl.
+pub trait DeviceSelect<T, I, Mode> {
+    type Result;
+
     /// Equivalent to psuedocode `out = inp[indices]`
-    fn select_axis(inp: &T, indices: &Indices, out: &mut R);
+    fn select_axis(inp: &T, indices: &I, out: &mut Self::Result);
 
     /// `inp[indices] += out`
-    fn select_add(inp: &mut T, indices: &Indices, out: &R);
+    fn select_add(inp: &mut T, indices: &I, out: &Self::Result);
 }
 
-macro_rules! select_01 {
-    ($Axis:expr, $SrcTy:tt, $DstTy:tt, {$($Dims:tt),*}) => {
-impl<$(const $Dims: usize),*> SelectAlongAxis<$SrcTy, usize, $DstTy, $Axis> for Cpu {
-    fn select_axis(inp: &$SrcTy, indices: &usize, out: &mut $DstTy) {
+// Select 1 element from 0th axis.
+impl<T, const M: usize> DeviceSelect<[T; M], usize, Index> for Cpu
+where
+    Self: ForEachElement<T>,
+    T: Copy + CountElements,
+    T::Dtype: for<'a> std::ops::AddAssign<&'a T::Dtype>,
+{
+    type Result = T;
+
+    fn select_axis(inp: &[T; M], indices: &usize, out: &mut Self::Result) {
         *out = inp[*indices];
     }
-    fn select_add(inp: &mut $SrcTy, indices: &usize, out: &$DstTy) {
+
+    fn select_add(inp: &mut [T; M], indices: &usize, out: &Self::Result) {
         Self::foreach_mr(&mut inp[*indices], out, &mut |a, b| *a += b);
     }
 }
-    };
-}
 
-macro_rules! select_0z {
-    ($Axis:expr, $SrcTy:tt, $DstTy:tt, {$($Dims:tt),*}) => {
-impl<$(const $Dims: usize),*> SelectAlongAxis<$SrcTy, [usize; Z], $DstTy, $Axis> for Cpu {
-    fn select_axis(inp: &$SrcTy, indices: &[usize; Z], out: &mut $DstTy) {
+// Select Z elements from 0th axis.
+impl<T, const M: usize, const Z: usize> DeviceSelect<[T; M], [usize; Z], Index> for Cpu
+where
+    Self: ForEachElement<T>,
+    T: Copy + CountElements,
+    T::Dtype: for<'a> std::ops::AddAssign<&'a T::Dtype>,
+{
+    type Result = [T; Z];
+
+    fn select_axis(inp: &[T; M], indices: &[usize; Z], out: &mut Self::Result) {
         for z in 0..Z {
             out[z] = inp[indices[z]];
         }
     }
-    fn select_add(inp: &mut $SrcTy, indices: &[usize; Z], out: &$DstTy) {
+    fn select_add(inp: &mut [T; M], indices: &[usize; Z], out: &Self::Result) {
         for z in 0..Z {
             Self::foreach_mr(&mut inp[indices[z]], &out[z], &mut |a, b| *a += b);
         }
     }
 }
-    };
-}
 
-macro_rules! select_nz {
-    ($Axis:expr, $SrcTy:tt, $IndTy:tt, $DstTy:tt, {$($Dims:tt),*}) => {
-impl<$(const $Dims: usize),*> SelectAlongAxis<$SrcTy, $IndTy, $DstTy, $Axis> for Cpu {
-    fn select_axis(inp: &$SrcTy, indices: &$IndTy, out: &mut $DstTy) {
+// Select elements from non-zero axis
+impl<T, I, const M: usize, SubMode> DeviceSelect<[T; M], [I; M], Recurse<SubMode>> for Cpu
+where
+    Self: DeviceSelect<T, I, SubMode>,
+{
+    type Result = [<Self as DeviceSelect<T, I, SubMode>>::Result; M];
+
+    fn select_axis(inp: &[T; M], indices: &[I; M], out: &mut Self::Result) {
         for m in 0..M {
             Self::select_axis(&inp[m], &indices[m], &mut out[m]);
         }
     }
-    fn select_add(inp: &mut $SrcTy, indices: &$IndTy, out: &$DstTy) {
+
+    fn select_add(inp: &mut [T; M], indices: &[I; M], out: &Self::Result) {
         for m in 0..M {
             Self::select_add(&mut inp[m], &indices[m], &out[m]);
         }
     }
 }
-    };
-}
 
-// 1d
-select_01!(-1, [f32; M], f32, { M });
-select_0z!(-1, [f32; M], [f32; Z], {M, Z});
-
-// 2d
-select_01!(0, [[f32; N]; M], [f32; N], {M, N});
-select_0z!(0, [[f32; N]; M], [[f32; N]; Z], {M, N, Z});
-select_nz!(-1, [[f32; N]; M], [usize; M], [f32; M], {M, N});
-select_nz!(-1, [[f32; N]; M], [[usize; Z]; M], [[f32; Z]; M], {M, N, Z});
-
-// 3d
-select_01!(0, [[[f32; O]; N]; M], [[f32; O]; N], {M, N, O});
-select_0z!(0, [[[f32; O]; N]; M], [[[f32; O]; N]; Z], {M, N, O, Z});
-select_nz!(1, [[[f32; O]; N]; M], [usize; M], [[f32; O]; M], {M, N, O});
-select_nz!(1, [[[f32; O]; N]; M], [[usize; Z]; M], [[[f32; O]; Z]; M], {M, N, O, Z});
-select_nz!(-1, [[[f32; O]; N]; M], [[usize; N]; M], [[f32; N]; M], {M, N, O});
-select_nz!(-1, [[[f32; O]; N]; M], [[[usize; Z]; N]; M], [[[f32; Z]; N]; M], {M, N, O, Z});
-
-// 4d
-select_01!(0, [[[[f32; P]; O]; N]; M], [[[f32; P]; O]; N], {M, N, O, P});
-select_0z!(0, [[[[f32; P]; O]; N]; M], [[[[f32; P]; O]; N]; Z], {M, N, O, P, Z});
-select_nz!(1, [[[[f32; P]; O]; N]; M], [usize; M], [[[f32; P]; O]; M], {M, N, O, P});
-select_nz!(1, [[[[f32; P]; O]; N]; M], [[usize; Z]; M], [[[[f32; P]; O]; Z]; M], {M, N, O, P, Z});
-select_nz!(2, [[[[f32; P]; O]; N]; M], [[usize; N]; M], [[[f32; P]; N]; M], {M, N, O, P});
-select_nz!(2, [[[[f32; P]; O]; N]; M], [[[usize; Z]; N]; M], [[[[f32; P]; Z]; N]; M], {M, N, O, P, Z});
-select_nz!(-1, [[[[f32; P]; O]; N]; M], [[[usize; O]; N]; M], [[[f32; O]; N]; M], {M, N, O, P});
-select_nz!(-1, [[[[f32; P]; O]; N]; M], [[[[usize; Z]; O]; N]; M], [[[[f32; Z]; O]; N]; M], {M, N, O, P, Z});
+// Broadcast select elements from non-zero axis.
+impl<T, I, const M: usize, SubMode> DeviceSelect<T, [I; M], Broadcast<SubMode>> for Cpu
+where
+    Self: DeviceSelect<T, I, SubMode>,
+{
+    type Result = [<Self as DeviceSelect<T, I, SubMode>>::Result; M];
+
+    fn select_axis(inp: &T, indices: &[I; M], out: &mut Self::Result) {
+        for m in 0..M {
+            Self::select_axis(inp, &indices[m], &mut out[m]);
+        }
+    }
+    fn select_add(inp: &mut T, indices: &[I; M], out: &Self::Result) {
+        for m in 0..M {
+            Self::select_add(inp, &indices[m], &out[m]);
+        }
+    }
+}
 
 #[cfg(test)]
 mod tests {
@@ -110,17 +143,17 @@ mod tests {
 
     #[test]
     fn test_select_1d_0() {
-        let a = [1.0, 2.0, 3.0];
-        let mut b = ZeroElements::ZEROS;
+        let a: [f32; 3] = [1.0, 2.0, 3.0];
+        let mut b: f32 = ZeroElements::ZEROS;
         Cpu::select_axis(&a, &1, &mut b);
         assert_eq!(b, 2.0);
     }
 
     #[test]
     fn test_select_1d_0z() {
-        let a = [1.0, 2.0, 3.0];
-        let mut b = ZeroElements::ZEROS;
-        Cpu::select_axis(&a, &[0, 1, 2, 2, 1, 0], &mut b);
+        let a: [f32; 3] = [1.0f32, 2.0, 3.0];
+        let mut b: [f32; 6] = ZeroElements::ZEROS;
+        <Cpu as DeviceSelect<_, _, Index>>::select_axis(&a, &[0, 1, 2, 2, 1, 0], &mut b);
         assert_eq!(b, [1.0, 2.0, 3.0, 3.0, 2.0, 1.0]);
     }
 
@@ -129,41 +162,51 @@ mod tests {
     #[test]
     fn test_select_2d_0() {
         let a = A_2D;
-        let mut b = ZeroElements::ZEROS;
+        let mut b: [f32; 3] = ZeroElements::ZEROS;
         Cpu::select_axis(&a, &0, &mut b);
         assert_eq!(b, [1.0, 2.0, 3.0]);
     }
 
     #[test]
     fn test_select_2d_0z() {
         let a = A_2D;
-        let mut b = ZeroElements::ZEROS;
-        Cpu::select_axis(&a, &[0, 0, 1], &mut b);
+        let mut b: [[f32; 3]; 3] = ZeroElements::ZEROS;
+        <Cpu as DeviceSelect<_, _, Index>>::select_axis(&a, &[0, 0, 1], &mut b);
         assert_eq!(b, [a[0], a[0], a[1]]);
     }
 
     #[test]
     fn test_select_2d_1() {
         let a = A_2D;
-        let mut b = ZeroElements::ZEROS;
-        <Cpu as SelectAlongAxis<_, _, _, -1>>::select_axis(&a, &[0, 1], &mut b);
+        let mut b: [f32; 2] = ZeroElements::ZEROS;
+        <Cpu as DeviceSelect<_, _, Recurse<Index>>>::select_axis(&a, &[0, 1], &mut b);
         assert_eq!(b, [1.0, 5.0]);
     }
 
     #[test]
     fn test_select_2d_1z() {
         let a = A_2D;
-        let mut b = ZeroElements::ZEROS;
-        Cpu::select_axis(&a, &[[0, 2], [1, 1]], &mut b);
+        let mut b: [[f32; 2]; 2] = ZeroElements::ZEROS;
+        <Cpu as DeviceSelect<_, _, Recurse<Index>>>::select_axis(&a, &[[0, 2], [1, 1]], &mut b);
         assert_eq!(b, [[1.0, 3.0], [5.0, 5.0]]);
     }
 
+    #[test]
+    fn test_select_broadcast_2d() {
+        let a = [[1.0], [2.0]];
+        let i: [[usize; 3]; 4] = [[0, 1, 0], [1, 1, 1], [0, 0, 0], [1, 0, 1]];
+        let mut b: [[[f32; 1]; 3]; 4] = ZeroElements::ZEROS;
+        <Cpu as DeviceSelect<_, _, Broadcast<Index>>>::select_axis(&a, &i, &mut b);
+        #[rustfmt::skip]
+        assert_eq!(b, [[[1.], [2.], [1.]], [[2.], [2.], [2.]], [[1.], [1.], [1.]], [[2.], [1.], [2.]]]);
+    }
+
     #[test]
     fn test_select_add_2d() {
         let mut a = [[0.0; 3]; 2];
         let b = [[1.0, 3.0], [5.0, 5.0]];
         let i = [[0, 2], [1, 1]];
-        Cpu::select_add(&mut a, &i, &b);
+        <Cpu as DeviceSelect<_, _, Recurse<Index>>>::select_add(&mut a, &i, &b);
         assert_eq!(a, [[1.0, 0.0, 3.0], [0.0, 10.0, 0.0]]);
     }
 
@@ -177,40 +220,40 @@ mod tests {
     #[test]
     fn test_select_3d_0() {
         let a = A_3D;
-        let mut b = ZeroElements::ZEROS;
+        let mut b: [[f32; 3]; 2] = ZeroElements::ZEROS;
         Cpu::select_axis(&a, &0, &mut b);
         assert_eq!(b, A_3D[0]);
     }
 
     #[test]
     fn test_select_3d_0z() {
         let a = A_3D;
-        let mut b = ZeroElements::ZEROS;
-        Cpu::select_axis(&a, &[0, 0, 1, 2, 3, 3], &mut b);
+        let mut b: [[[f32; 3]; 2]; 6] = ZeroElements::ZEROS;
+        <Cpu as DeviceSelect<_, _, Index>>::select_axis(&a, &[0, 0, 1, 2, 3, 3], &mut b);
         assert_eq!(b, [A_3D[0], A_3D[0], A_3D[1], A_3D[2], A_3D[3], A_3D[3]]);
     }
 
     #[test]
     fn test_select_3d_1() {
         let a = A_3D;
-        let mut b = ZeroElements::ZEROS;
-        <Cpu as SelectAlongAxis<_, _, _, 1>>::select_axis(&a, &[0, 0, 1, 1], &mut b);
+        let mut b: [[f32; 3]; 4] = ZeroElements::ZEROS;
+        <Cpu as DeviceSelect<_, _, Recurse<Index>>>::select_axis(&a, &[0, 0, 1, 1], &mut b);
         assert_eq!(b, [A_3D[0][0], A_3D[1][0], A_3D[2][1], A_3D[3][1]]);
     }
 
     #[test]
     fn test_select_3d_1z() {
         let a = A_3D;
-        let mut b = ZeroElements::ZEROS;
-        <Cpu as SelectAlongAxis<_, _, _, 1>>::select_axis(&a, &[[0], [0], [1], [1]], &mut b);
+        let mut b: [[[f32; 3]; 1]; 4] = ZeroElements::ZEROS;
+        <Cpu as DeviceSelect<_, _, Recurse<Index>>>::select_axis(&a, &[[0], [0], [1], [1]], &mut b);
         assert_eq!(b, [[A_3D[0][0]], [A_3D[1][0]], [A_3D[2][1]], [A_3D[3][1]]]);
     }
 
     #[test]
     fn test_select_3d_2() {
         let a = A_3D;
-        let mut b = ZeroElements::ZEROS;
-        <Cpu as SelectAlongAxis<_, _, _, -1>>::select_axis(
+        let mut b: [[f32; 2]; 4] = ZeroElements::ZEROS;
+        <Cpu as DeviceSelect<_, _, Recurse<Recurse<Index>>>>::select_axis(
             &a,
             &[[1, 0], [0, 1], [0, 0], [1, 1]],
             &mut b,
@@ -230,7 +273,7 @@ mod tests {
     fn test_select_3d_2z() {
         let a = A_3D;
         let mut b: [[[f32; 1]; 2]; 4] = ZeroElements::ZEROS;
-        <Cpu as SelectAlongAxis<_, _, _, -1>>::select_axis(
+        <Cpu as DeviceSelect<_, _, Recurse<Recurse<Index>>>>::select_axis(
             &a,
             &[[[1], [0]], [[0], [1]], [[0], [0]], [[1], [1]]],
             &mut b,