From 41ac046471b2d99c3779352f516706e54b3f187e Mon Sep 17 00:00:00 2001
From: Tim Holy <tim.holy@gmail.com>
Date: Thu, 7 Apr 2022 14:31:38 -0500
Subject: [PATCH] Improve integration with Interpolations

This defines `Interpolations.popwrapper` on CenterIndexedArrays,
allowing certain operations to be performed without the caller
having to unwrap the array.
---
 src/CenterIndexedArrays.jl |  1 +
 test/runtests.jl           | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/src/CenterIndexedArrays.jl b/src/CenterIndexedArrays.jl
index 8aa4e28..b969258 100644
--- a/src/CenterIndexedArrays.jl
+++ b/src/CenterIndexedArrays.jl
@@ -97,6 +97,7 @@ function Base.similar(bc::Broadcast.Broadcasted{Broadcast.ArrayStyle{CenterIndex
 end
 
 Base.parent(A::CenterIndexedArray) = A.data
+Interpolations.popwrapper(A::CenterIndexedArray) = parent(A)
 
 function Base.showarg(io::IO, A::CenterIndexedArray, toplevel)
     print(io, "CenterIndexedArray(")
diff --git a/test/runtests.jl b/test/runtests.jl
index 7efa677..a7c7401 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -174,3 +174,14 @@ end
     @test A+A == CenterIndexedArray(dat+dat)
     @test isa(A .+ 1, CenterIndexedArray)
 end
+
+@testset "Interpolations integration" begin
+    y = 1:3
+    yc = CenterIndexedArray(y)
+    itp = interpolate(yc, BSpline(Linear()))
+    @test itp(0.2) ≈ 2.2
+    y = [4.0, 1.0, 0.0, 1.0, 4.0]
+    yc = CenterIndexedArray(y)
+    itp = interpolate!(yc, BSpline(Quadratic(InPlaceQ(OnCell()))))
+    @test itp(0.2) ≈ 0.2^2
+end