From 6df463271932c3cd8311ea0cec8befafad79543c Mon Sep 17 00:00:00 2001
From: Magnus Ulimoen <flymagnus@gmail.com>
Date: Wed, 15 Apr 2020 00:37:46 +0200
Subject: [PATCH] add back specialization

---
 sbp/src/lib.rs               |  1 +
 sbp/src/operators.rs         | 30 ++++++++++++------------------
 sbp/src/operators/upwind4.rs | 15 ++++++---------
 3 files changed, 19 insertions(+), 27 deletions(-)

diff --git a/sbp/src/lib.rs b/sbp/src/lib.rs
index 2f37194..6192d39 100644
--- a/sbp/src/lib.rs
+++ b/sbp/src/lib.rs
@@ -1,4 +1,5 @@
 #![feature(str_strip)]
+#![feature(specialization)]
 
 #[cfg(feature = "f32")]
 pub type Float = f32;
diff --git a/sbp/src/operators.rs b/sbp/src/operators.rs
index 8b02820..4d99597 100644
--- a/sbp/src/operators.rs
+++ b/sbp/src/operators.rs
@@ -25,7 +25,7 @@ pub trait SbpOperator2d: Copy + Clone {
 }
 
 impl<SBPeta: SbpOperator1d, SBPxi: SbpOperator1d> SbpOperator2d for (SBPeta, SBPxi) {
-    fn diffxi(&self, prev: ArrayView2<Float>, mut fut: ArrayViewMut2<Float>) {
+    default fn diffxi(&self, prev: ArrayView2<Float>, mut fut: ArrayViewMut2<Float>) {
         assert_eq!(prev.shape(), fut.shape());
         for (r0, r1) in prev.outer_iter().zip(fut.outer_iter_mut()) {
             self.1.diff(r0, r1)
@@ -50,26 +50,23 @@ impl<SBPeta: SbpOperator1d, SBPxi: SbpOperator1d> SbpOperator2d for (SBPeta, SBP
 }
 
 impl<SBP: SbpOperator1d> SbpOperator2d for SBP {
-    fn diffxi(&self, prev: ArrayView2<Float>, mut fut: ArrayViewMut2<Float>) {
-        assert_eq!(prev.shape(), fut.shape());
-        for (r0, r1) in prev.outer_iter().zip(fut.outer_iter_mut()) {
-            self.diff(r0, r1)
-        }
+    fn diffxi(&self, prev: ArrayView2<Float>, fut: ArrayViewMut2<Float>) {
+        <(SBP, SBP) as SbpOperator2d>::diffxi(&(*self, *self), prev, fut)
     }
     fn diffeta(&self, prev: ArrayView2<Float>, fut: ArrayViewMut2<Float>) {
-        self.diffxi(prev.reversed_axes(), fut.reversed_axes())
+        <(SBP, SBP) as SbpOperator2d>::diffeta(&(*self, *self), prev, fut)
     }
     fn hxi(&self) -> &'static [Float] {
-        self.h()
+        <(SBP, SBP) as SbpOperator2d>::hxi(&(*self, *self))
     }
     fn heta(&self) -> &'static [Float] {
-        self.h()
+        <(SBP, SBP) as SbpOperator2d>::heta(&(*self, *self))
     }
     fn is_h2xi(&self) -> bool {
-        self.is_h2()
+        <(SBP, SBP) as SbpOperator2d>::is_h2xi(&(*self, *self))
     }
     fn is_h2eta(&self) -> bool {
-        self.is_h2()
+        <(SBP, SBP) as SbpOperator2d>::is_h2eta(&(*self, *self))
     }
 }
 
@@ -83,7 +80,7 @@ pub trait UpwindOperator2d: SbpOperator2d + Copy + Clone {
 }
 
 impl<UOeta: UpwindOperator1d, UOxi: UpwindOperator1d> UpwindOperator2d for (UOeta, UOxi) {
-    fn dissxi(&self, prev: ArrayView2<Float>, mut fut: ArrayViewMut2<Float>) {
+    default fn dissxi(&self, prev: ArrayView2<Float>, mut fut: ArrayViewMut2<Float>) {
         assert_eq!(prev.shape(), fut.shape());
         for (r0, r1) in prev.outer_iter().zip(fut.outer_iter_mut()) {
             self.1.diss(r0, r1);
@@ -96,14 +93,11 @@ impl<UOeta: UpwindOperator1d, UOxi: UpwindOperator1d> UpwindOperator2d for (UOet
 }
 
 impl<UO: UpwindOperator1d> UpwindOperator2d for UO {
-    fn dissxi(&self, prev: ArrayView2<Float>, mut fut: ArrayViewMut2<Float>) {
-        assert_eq!(prev.shape(), fut.shape());
-        for (r0, r1) in prev.outer_iter().zip(fut.outer_iter_mut()) {
-            self.diss(r0, r1);
-        }
+    fn dissxi(&self, prev: ArrayView2<Float>, fut: ArrayViewMut2<Float>) {
+        <(UO, UO) as UpwindOperator2d>::dissxi(&(*self, *self), prev, fut)
     }
     fn disseta(&self, prev: ArrayView2<Float>, fut: ArrayViewMut2<Float>) {
-        self.dissxi(prev.reversed_axes(), fut.reversed_axes())
+        <(UO, UO) as UpwindOperator2d>::disseta(&(*self, *self), prev, fut)
     }
 }
 
diff --git a/sbp/src/operators/upwind4.rs b/sbp/src/operators/upwind4.rs
index ba0f362..85c5b3c 100644
--- a/sbp/src/operators/upwind4.rs
+++ b/sbp/src/operators/upwind4.rs
@@ -291,10 +291,10 @@ impl SbpOperator1d for Upwind4 {
     }
 }
 
-/*
+impl<SBP: SbpOperator1d> SbpOperator2d for (Upwind4, SBP) {
     fn diffxi(&self, prev: ArrayView2<Float>, mut fut: ArrayViewMut2<Float>) {
         assert_eq!(prev.shape(), fut.shape());
-        assert!(prev.shape()[1] >= 2 * Self::BLOCK.len());
+        assert!(prev.shape()[1] >= 2 * Upwind4::BLOCK.len());
 
         match (prev.strides(), fut.strides()) {
             ([_, 1], [_, 1]) => {
@@ -306,15 +306,13 @@ impl SbpOperator1d for Upwind4 {
             ([_, _], [_, _]) => {
                 // Fallback, work row by row
                 for (r0, r1) in prev.outer_iter().zip(fut.outer_iter_mut()) {
-                    Self.diff1d(r0, r1);
+                    Upwind4.diff(r0, r1);
                 }
             }
             _ => unreachable!("Should only be two elements in the strides vectors"),
         }
     }
-
 }
-*/
 
 #[test]
 fn upwind4_test() {
@@ -417,10 +415,10 @@ impl UpwindOperator1d for Upwind4 {
     }
 }
 
-/*
+impl<SBP: UpwindOperator1d> UpwindOperator2d for (Upwind4, SBP) {
     fn dissxi(&self, prev: ArrayView2<Float>, mut fut: ArrayViewMut2<Float>) {
         assert_eq!(prev.shape(), fut.shape());
-        assert!(prev.shape()[1] >= 2 * Self::BLOCK.len());
+        assert!(prev.shape()[1] >= 2 * Upwind4::BLOCK.len());
 
         match (prev.strides(), fut.strides()) {
             ([_, 1], [_, 1]) => {
@@ -432,14 +430,13 @@ impl UpwindOperator1d for Upwind4 {
             ([_, _], [_, _]) => {
                 // Fallback, work row by row
                 for (r0, r1) in prev.outer_iter().zip(fut.outer_iter_mut()) {
-                    Self.diss1d(r0, r1);
+                    Upwind4.diss(r0, r1);
                 }
             }
             _ => unreachable!("Should only be two elements in the strides vectors"),
         }
     }
 }
-*/
 
 #[test]
 fn upwind4_test2() {