view preservs metadata

Author: Pietro Vertechi

README.md

@@ -1,5 +1,8 @@
 # MetadataArrays
 
+[![Build Status](https://travis-ci.org/piever/MetadataArrays.jl.svg?branch=master)](https://travis-ci.org/piever/MetadataArrays.jl)
+[![codecov.io](http://codecov.io/github/piever/MetadataArrays.jl/coverage.svg?branch=master)](http://codecov.io/github/piever/MetadataArrays.jl?branch=master)
+
 Implementation of arrays with metadata.
 
 ## Metadata Arrays
@@ -34,6 +37,16 @@ Dict{String,String} with 3 entries:
   "Louise" => "Placebo"
 ```
 
+`metadata` is preserved when taking views:
+
+```julia
+julia> metadata(view(s, 1:2))
+Dict{String,String} with 3 entries:
+  "John"   => "Treatment"
+  "Jane"   => "Placebo"
+  "Louise" => "Placebo"
+```
+
 `s` can be used as a regular `AbstractArray` (meaning all operations that work on `AbstractArray` should work on a `MetadataArray` out of the box:
 
 ```julia

src/metadataarray.jl

@@ -57,3 +57,8 @@ Base.parent(s::MetadataArray) = s.parent
 Returns metadata for `s`.
 """
 metadata(s::MetadataArray) = s.metadata
+
+metadata(s::SubArray) = metadata(parent(s))
+
+metadata(s::T) where {T<:AbstractArray} =
+    error("Type $T has no method for metadata")

test/runtests.jl

@@ -11,6 +11,9 @@ end
     @test length(sv) == 4
     @test collect(sv) == parent(sv) == copy(sv)
     @test metadata(sv) == "Numbers"
+    s_view1 = view(sv, 1:3)
+    s_view2 = view(s_view1, 1:2)
+    @test metadata(s_view1) == metadata(s_view2) == "Numbers"
     sv[3] = 50
     @test all(sv .== [1, 3, 50, 4])
     @test eltype(sv) == Int