Fix potential type instability in unblock, add intersect for BlockRange (#125)

* Fix potential type instability in unblock

* intersect for BlockRange

* Update views.jl

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "BlockArrays"
 uuid = "8e7c35d0-a365-5155-bbbb-fb81a777f24e"
-version = "0.12.9"
+version = "0.12.10"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/BlockArrays.jl

@@ -28,7 +28,7 @@ import Base: @propagate_inbounds, Array, to_indices, to_index,
             RangeIndex, Int, Integer, Number,
             +, -, *, /, \, min, max, isless, in, copy, copyto!, axes, @deprecate,
             BroadcastStyle, checkbounds, throw_boundserror, 
-            ones, zeros
+            ones, zeros, intersect
 using Base: ReshapedArray, dataids
 
 

src/blockindices.jl

@@ -362,3 +362,6 @@ last(iter::BlockRange)  = Block(map(last, iter.indices))
 end
 _in(b, ::Tuple{}, ::Tuple{}, ::Tuple{}) = b
 @inline _in(b, i, start, stop) = _in(b & (start[1] <= i[1] <= stop[1]), tail(i), tail(start), tail(stop))
+
+# We sometimes need intersection of BlockRange to return a BlockRange
+intersect(a::BlockRange{1}, b::BlockRange{1}) = BlockRange(intersect(a.indices[1], b.indices[1]))

src/views.jl

@@ -7,14 +7,11 @@ Returns the indices associated with a block as a `BlockSlice`.
 """
 function unblock(A, inds, I)
     B = first(I)
-    if length(inds) == 0
-        # Allow `ones(2)[Block(1)[1:1], Block(1)[1:1]]` which is
-        # similar to `ones(2)[1:1, 1:1]`.
-        BlockSlice(B,Base.OneTo(1))
-    else
-        BlockSlice(B,inds[1][B])
-    end
+    BlockSlice(B,inds[1][B])
 end
+# Allow `ones(2)[Block(1)[1:1], Block(1)[1:1]]` which is
+# similar to `ones(2)[1:1, 1:1]`.
+unblock(A, ::Tuple{}, I) = BlockSlice(first(I),Base.OneTo(1))
 
 to_index(::Block) = throw(ArgumentError("Block must be converted by to_indices(...)"))
 to_index(::BlockIndex) = throw(ArgumentError("BlockIndex must be converted by to_indices(...)"))

test/test_blockindices.jl

@@ -88,6 +88,8 @@ import BlockArrays: BlockIndex, BlockIndexRange, BlockSlice
         @test Base.OneTo.(1:5) isa Vector{Base.OneTo{Int}} #98
         @test Base.OneTo(5)[Block.(1:1)] === Base.OneTo(5)
         @test_throws BlockBoundsError Base.OneTo(5)[Block.(1:3)]
+
+        @test intersect(Block.(2:5), Block.(3:6)) ≡ Block.(3:5)
     end
 end