more SubArray functionality (addressing #93):

 - works on integer inputs
 - better handling of calling sub on a SubArray

Author: GeorgeXing

j/tensor.j

@@ -1038,18 +1038,25 @@ end
 
 ## subarrays ##
 
-type SubArray{T,N,A<:AbstractArray,I<:(Indices...)} <: AbstractArray{T,N}
+type SubArray{T,N,A<:AbstractArray,I<:(AbstractVector...)} <: AbstractArray{T,N}
     parent::A
     indexes::I
     dims::Dims
 
     SubArray(p::A, i::I) = new(p, i, map(length, i))
 end
 
-sub{T,N}(A::AbstractArray{T,N}, i::NTuple{N,Indices}) =
+sub{T,N}(A::AbstractArray{T,N}, i::NTuple{N,AbstractVector}) =
     SubArray{T,N,typeof(A),typeof(i)}(A, i)
 
-sub(A::AbstractArray, i::Indices...) = sub(A, i)
+#change integer indexes into Range1 objects
+sub(A::AbstractArray, i::Indices...) =
+    sub(A, ntuple(length(i), j -> isa(i[j],AbstractVector) ? i[j] :
+                                                            (i[j]:i[j])))
+
+sub(A::SubArray, i::Indices...) =
+    sub(A.parent, ntuple(length(i), j -> isa(i[j],AbstractVector) ? A.indexes[j][i[j]] :
+                                                                    (A.indexes[j][i[j]]):(A.indexes[j][i[j]])))
 
 size(s::SubArray) = s.dims
 ndims{T,N}(s::SubArray{T,N}) = N