From 060bf95a78f33cd5f29edd4d3e54e65009fa5bec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lars=20G=C3=B6ttgens?= <lars.goettgens@rwth-aachen.de>
Date: Fri, 18 Aug 2023 20:54:21 +0200
Subject: [PATCH] Add `setindex!` for `MatElem` with linear indexing (#1407)

---
 src/Matrix.jl               | 23 +++++++++++++++++++++++
 src/generic/Matrix.jl       | 17 -----------------
 test/generic/Matrix-test.jl | 14 ++++++++++++++
 3 files changed, 37 insertions(+), 17 deletions(-)

diff --git a/src/Matrix.jl b/src/Matrix.jl
index 6a18713a48..06ace4281d 100644
--- a/src/Matrix.jl
+++ b/src/Matrix.jl
@@ -440,6 +440,29 @@ Base.@propagate_inbounds function Base.setindex!(a::MatrixElem{T}, x, I::Cartesi
    a
 end
 
+# linear indexing for row- or column- vectors
+Base.@propagate_inbounds function getindex(M::MatrixElem, i::Integer)
+   if nrows(M) == 1
+      M[1, i]
+   elseif ncols(M) == 1
+      M[i, 1]
+   else
+      throw(ArgumentError("linear indexing not supported for non-vector matrices"))
+   end
+end
+
+Base.@propagate_inbounds function setindex!(M::MatrixElem, x, i::Integer)
+   if nrows(M) == 1
+      M[1, i] = x
+      return M
+   elseif ncols(M) == 1
+      M[i, 1] = x
+      return M
+   else
+      throw(ArgumentError("linear indexing not supported for non-vector matrices"))
+   end
+end
+
 # iteration
 
 function Base.iterate(a::MatrixElem{T}, ij=(0, 1)) where T <: NCRingElement
diff --git a/src/generic/Matrix.jl b/src/generic/Matrix.jl
index 79796c66a6..cbee44fb6b 100644
--- a/src/generic/Matrix.jl
+++ b/src/generic/Matrix.jl
@@ -100,23 +100,6 @@ function deepcopy_internal(d::MatSpaceView{T}, dict::IdDict) where T <: NCRingEl
    return MatSpaceView(deepcopy_internal(d.entries, dict), d.base_ring)
 end
 
-###############################################################################
-#
-#   getindex
-#
-###############################################################################
-
-# linear indexing for row- or column- vectors
-Base.@propagate_inbounds function getindex(M::MatElem, x::Integer)
-   if nrows(M) == 1
-      M[1, x]
-   elseif ncols(M) == 1
-      M[x, 1]
-   else
-      throw(ArgumentError("linear indexing not supported for non-vector matrices"))
-   end
-end
-
 function Base.view(M::Mat{T}, rows::AbstractUnitRange{Int}, cols::AbstractUnitRange{Int}) where T <: NCRingElement
    return MatSpaceView(view(M.entries, rows, cols), M.base_ring)
 end
diff --git a/test/generic/Matrix-test.jl b/test/generic/Matrix-test.jl
index 0d7a615d65..f685826cd4 100644
--- a/test/generic/Matrix-test.jl
+++ b/test/generic/Matrix-test.jl
@@ -747,6 +747,20 @@ end
       elseif length(A) >= 1
          @test_throws ArgumentError A[1]
       end
+      A = deepcopy(A)
+      if nr == 1
+         c = rand(1:nc)
+         d = rand(1:nc)
+         A[c] = A[d]
+         @test A[c] == A[1, d]
+      elseif nc == 1
+         r = rand(1:nr)
+         s = rand(1:nr)
+         A[r] = A[s]
+         @test A[r] == A[s, 1]
+      elseif length(A) >= 1
+         @test_throws ArgumentError (A[1] = zero(base_ring(A)))
+      end
    end
 
    for (_, (R, rand_params)) in RINGS