Exploit special case broadcasting for *, - , +, /, \ (#94)

* Exploit special case broadcasting for *, - , +, /, \

* Use broadcast instead of map

* Don't override broadcasted

Author: dlfivefifty

src/blockbroadcast.jl

@@ -195,3 +195,24 @@ end
     bcf = Broadcast.flatten(Broadcasted{Nothing}(bc.f, bc.args, bc.axes))
     return Broadcasted{Style}(bcf.f, bcf.args, bcf.axes)
 end
+
+
+for op in (:+, :-, :*)
+    @eval function copy(bc::Broadcasted{BlockStyle{N},<:Any,typeof($op),<:Tuple{<:BlockArray{<:Number,N}}}) where N 
+        (A,) = bc.args
+        _BlockArray(broadcast(a -> broadcast($op, a), A.blocks), blocksizes(A))        
+    end
+end
+
+for op in (:+, :-, :*, :/, :\)
+    @eval begin
+        function copy(bc::Broadcasted{BlockStyle{N},<:Any,typeof($op),<:Tuple{<:Number,<:BlockArray{<:Number,N}}}) where N
+            x,A = bc.args
+            _BlockArray(broadcast((x,a) -> broadcast($op, x, a), x, A.blocks), blocksizes(A))
+        end
+        function copy(bc::Broadcasted{BlockStyle{N},<:Any,typeof($op),<:Tuple{<:BlockArray{<:Number,N},<:Number}}) where N 
+            A,x = bc.args
+            _BlockArray(broadcast((a,x) -> broadcast($op, a, x), A.blocks,x), blocksizes(A))            
+        end
+    end
+end

test/test_blockbroadcast.jl

@@ -98,4 +98,16 @@ using BlockArrays, Test
         z2 = copy(z)
         @test (@. z = x + y + z; z) == (@. z2 = x2 + y2 + z2; z2)
     end
+
+    @testset "Special broadcast" begin
+        v = mortar([1:3,4:7])
+        @test broadcast(+, v) isa BlockVector{Int,Vector{UnitRange{Int}}}
+        @test broadcast(+, v) == v
+        @test broadcast(-, v) isa BlockVector{Int,Vector{StepRange{Int,Int}}}
+        @test broadcast(-, v) == -v == -Vector(v)
+        @test broadcast(+, v, 1) isa BlockVector{Int,Vector{UnitRange{Int}}}
+        @test broadcast(+, v, 1) == Vector(v).+1
+        @test broadcast(*, 2, v) isa BlockVector{Int,Vector{StepRange{Int,Int}}}
+        @test broadcast(*, 2, v) == 2Vector(v)
+    end
 end