From 3d55528042a103e51985831e1a8eb75e419018d1 Mon Sep 17 00:00:00 2001
From: mschauer <moritzschauer@web.de>
Date: Thu, 27 Sep 2018 15:42:23 +0200
Subject: [PATCH 1/3] Special case flatten of iterators of static arrays

---
 src/StaticArrays.jl | 1 +
 src/flatten.jl      | 6 ++++++
 2 files changed, 7 insertions(+)
 create mode 100644 src/flatten.jl

diff --git a/src/StaticArrays.jl b/src/StaticArrays.jl
index 1528f371..99218c0b 100644
--- a/src/StaticArrays.jl
+++ b/src/StaticArrays.jl
@@ -114,6 +114,7 @@ include("svd.jl")
 include("lu.jl")
 include("qr.jl")
 include("deque.jl")
+include("flatten.jl")
 include("io.jl")
 
 include("FixedSizeArrays.jl")
diff --git a/src/flatten.jl b/src/flatten.jl
new file mode 100644
index 00000000..90d121aa
--- /dev/null
+++ b/src/flatten.jl
@@ -0,0 +1,6 @@
+# Special case flatten of iterators of static arrays.
+import Base.Iterators: flatten_iteratorsize, flatten_length
+flatten_iteratorsize(::Union{Base.HasShape, Base.HasLength}, ::Type{<:Union{SArray,MArray}}) = Base.HasLength()
+function flatten_length(f, T::Type{<:Union{SArray,MArray}})
+    length(T)*length(f.it)
+end

From e07ad4fbd3da4054c348af45ed740354d3b782dc Mon Sep 17 00:00:00 2001
From: mschauer <moritzschauer@web.de>
Date: Thu, 27 Sep 2018 16:11:53 +0200
Subject: [PATCH 2/3] Tests and refinement

---
 src/flatten.jl   |  4 ++--
 test/flatten.jl  | 13 +++++++++++++
 test/runtests.jl |  1 +
 3 files changed, 16 insertions(+), 2 deletions(-)
 create mode 100644 test/flatten.jl

diff --git a/src/flatten.jl b/src/flatten.jl
index 90d121aa..34222d91 100644
--- a/src/flatten.jl
+++ b/src/flatten.jl
@@ -1,6 +1,6 @@
 # Special case flatten of iterators of static arrays.
 import Base.Iterators: flatten_iteratorsize, flatten_length
-flatten_iteratorsize(::Union{Base.HasShape, Base.HasLength}, ::Type{<:Union{SArray,MArray}}) = Base.HasLength()
-function flatten_length(f, T::Type{<:Union{SArray,MArray}})
+flatten_iteratorsize(::Union{Base.HasShape, Base.HasLength}, ::Type{<:StaticArray}) = Base.HasLength()
+function flatten_length(f, T::Type{<:StaticArray})
     length(T)*length(f.it)
 end
diff --git a/test/flatten.jl b/test/flatten.jl
new file mode 100644
index 00000000..c88735ca
--- /dev/null
+++ b/test/flatten.jl
@@ -0,0 +1,13 @@
+using StaticArrays, Test
+
+@testset "Iterators.flatten" begin
+    for x in [SVector(1.0, 2.0), MVector(1.0, 2.0),
+            @SMatrix([1.0 2.0; 3.0 4.0]), @MMatrix([1.0 2.0]),
+            Size(1,2)([1.0 2.0])
+            ]
+        X = [x,x,x]
+        @test length(Iterators.flatten(X)) == length(X)*length(x)
+        @test collect(Iterators.flatten(typeof(x)[])) == []
+        @test collect(Iterators.flatten(X)) == [x..., x..., x...]
+    end
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index 5d04b1ac..fd64c65b 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -40,6 +40,7 @@ include("lu.jl")
 Random.seed!(42); include("qr.jl")
 Random.seed!(42); include("chol.jl") # hermitian_type(::Type{Any}) for block algorithm
 include("deque.jl")
+include("flatten.jl")
 include("io.jl")
 include("svd.jl")
 Random.seed!(42); include("fixed_size_arrays.jl")

From 76eea3c6dcaa34207aebe0f2dadf228a044808b6 Mon Sep 17 00:00:00 2001
From: mschauer <moritzschauer@web.de>
Date: Thu, 27 Sep 2018 16:41:06 +0200
Subject: [PATCH 3/3] Handle mixed size iterators

---
 src/flatten.jl  | 4 ++--
 test/flatten.jl | 2 ++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/flatten.jl b/src/flatten.jl
index 34222d91..727e4c1c 100644
--- a/src/flatten.jl
+++ b/src/flatten.jl
@@ -1,6 +1,6 @@
 # Special case flatten of iterators of static arrays.
 import Base.Iterators: flatten_iteratorsize, flatten_length
-flatten_iteratorsize(::Union{Base.HasShape, Base.HasLength}, ::Type{<:StaticArray}) = Base.HasLength()
-function flatten_length(f, T::Type{<:StaticArray})
+flatten_iteratorsize(::Union{Base.HasShape, Base.HasLength}, ::Type{<:StaticArray{S}}) where {S} = Base.HasLength()
+function flatten_length(f, T::Type{<:StaticArray{S}}) where {S}
     length(T)*length(f.it)
 end
diff --git a/test/flatten.jl b/test/flatten.jl
index c88735ca..9c8796c8 100644
--- a/test/flatten.jl
+++ b/test/flatten.jl
@@ -10,4 +10,6 @@ using StaticArrays, Test
         @test collect(Iterators.flatten(typeof(x)[])) == []
         @test collect(Iterators.flatten(X)) == [x..., x..., x...]
     end
+    @test collect(Iterators.flatten([SVector(1,1), SVector(1)])) == [1,1,1]
+    @test_throws ArgumentError length(Iterators.flatten([SVector(1,1), SVector(1)]))
 end