From 70fb0384cf465a2cbe64c0ba8b532e85ca12080b Mon Sep 17 00:00:00 2001
From: Jishnu Bhattacharya <jishnub.github@gmail.com>
Date: Wed, 8 May 2024 23:10:46 +0530
Subject: [PATCH 1/2] Reshape for a OneElement

---
 src/oneelement.jl | 10 ++++++++++
 test/runtests.jl  | 10 ++++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/oneelement.jl b/src/oneelement.jl
index f6204abb..c72bcd2d 100644
--- a/src/oneelement.jl
+++ b/src/oneelement.jl
@@ -372,6 +372,16 @@ function broadcasted(::DefaultArrayStyle{N}, ::typeof(\), x::Number, r::OneEleme
     OneElement(x \ r.val, r.ind, axes(r))
 end
 
+# reshape
+
+function Base.reshape(A::OneElement, shape::Tuple{Vararg{Int}})
+    prod(shape) == length(A) || throw(DimensionMismatch("new dimension $shape must be consistent with array size $(length(A))"))
+    # we use the fact that the linear index of the non-zero value is preserved
+    oldlinind = LinearIndices(A)[A.ind...]
+    newcartind = CartesianIndices(shape)[oldlinind]
+    OneElement(A.val, Tuple(newcartind), shape)
+end
+
 # show
 _maybesize(t::Tuple{Base.OneTo{Int}, Vararg{Base.OneTo{Int}}}) = size.(t,1)
 _maybesize(t) = t
diff --git a/test/runtests.jl b/test/runtests.jl
index 2e2aba22..463a4b40 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -2215,6 +2215,16 @@ end
         @test adjoint(A) == OneElement(3, (1,2), (1,4))
     end
 
+    @testset "reshape" begin
+        for O in (OneElement(2, (2,3), (4,5)), OneElement(2, (2,), (20,)),
+                    OneElement(2, (1,2,2), (2,2,5)))
+            A = Array(O)
+            for shp in ((2,5,2), (5,1,4), (20,), (2,2,5,1,1))
+                @test reshape(O, shp) == reshape(A, shp)
+            end
+        end
+    end
+
     @testset "isassigned" begin
         f = OneElement(2, (3,3), (4,4))
         @test !isassigned(f, 0, 0)

From b4a19a791e3b2e129b577fd3e7d6f9b0534b4524 Mon Sep 17 00:00:00 2001
From: Jishnu Bhattacharya <jishnub.github@gmail.com>
Date: Wed, 8 May 2024 23:14:22 +0530
Subject: [PATCH 2/2] Tests for 0D

---
 test/runtests.jl | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/test/runtests.jl b/test/runtests.jl
index 463a4b40..d4b2bb95 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -2223,6 +2223,8 @@ end
                 @test reshape(O, shp) == reshape(A, shp)
             end
         end
+        O = OneElement(2, (), ())
+        @test reshape(O, ()) === O
     end
 
     @testset "isassigned" begin