Add default IsScalar trait

Author: pabloferz

base/array.jl

@@ -206,6 +206,7 @@ promote_rule{T,n,S}(::Type{Array{T,n}}, ::Type{Array{S,n}}) = Array{promote_type
 
 # make a collection similar to `c` and appropriate for collecting `itr`
 _similar_for(c::AbstractArray, T, itr, ::SizeUnknown) = similar(c, T, 0)
+_similar_for(c::AbstractArray, T, itr, ::IsScalar) = similar(c, T, ())
 _similar_for(c::AbstractArray, T, itr, ::HasLength) = similar(c, T, Int(length(itr)::Integer))
 _similar_for(c::AbstractArray, T, itr, ::HasShape) = similar(c, T, convert(Dims,size(itr)))
 _similar_for(c, T, itr, isz) = similar(c, T)
@@ -226,7 +227,7 @@ collect(itr) = _collect(1:1 #= Array =#, itr, iteratoreltype(itr), iteratorsize(
 
 collect_similar(cont, itr) = _collect(cont, itr, iteratoreltype(itr), iteratorsize(itr))
 
-_collect(cont, itr, ::HasEltype, isz::Union{HasLength,HasShape}) =
+_collect(cont, itr, ::HasEltype, isz::Union{HasLength,HasShape,IsScalar}) =
     copy!(_similar_for(cont, eltype(itr), itr, isz), itr)
 
 function _collect(cont, itr, ::HasEltype, isz::SizeUnknown)

base/generator.jl

@@ -29,16 +29,19 @@ end
 
 abstract IteratorSize
 immutable SizeUnknown <: IteratorSize end
+immutable IsScalar <: IteratorSize end
 immutable HasLength <: IteratorSize end
 immutable HasShape <: IteratorSize end
 immutable IsInfinite <: IteratorSize end
 
 iteratorsize(x) = iteratorsize(typeof(x))
-iteratorsize(::Type) = HasLength()  # HasLength is the default
+iteratorsize(::Type) = IsScalar()  # IsScalar is the default
 
 and_iteratorsize{T}(isz::T, ::T) = isz
 and_iteratorsize(::HasLength, ::HasShape) = HasLength()
 and_iteratorsize(::HasShape, ::HasLength) = HasLength()
+and_iteratorsize(::IsScalar, ::Union{HasLength,HasShape}) = IsScalar()
+and_iteratorsize(::Union{HasLength,HasShape}, ::IsScalar) = IsScalar()
 and_iteratorsize(a, b) = SizeUnknown()
 
 abstract IteratorEltype

base/iterator.jl

@@ -38,6 +38,7 @@ iteratoreltype{I}(::Type{Enumerate{I}}) = iteratoreltype(I)
 abstract AbstractZipIterator
 
 zip_iteratorsize(a, b) = and_iteratorsize(a,b) # as `and_iteratorsize` but inherit `Union{HasLength,IsInfinite}` of the shorter iterator
+zip_iteratorsize(::IsScalar, ::IsInfinite) = IsScalar()
 zip_iteratorsize(::HasLength, ::IsInfinite) = HasLength()
 zip_iteratorsize(::HasShape, ::IsInfinite) = HasLength()
 zip_iteratorsize(a::IsInfinite, b) = zip_iteratorsize(b,a)
@@ -413,6 +414,9 @@ iteratorsize{I1,I2}(::Type{Prod{I1,I2}}) = prod_iteratorsize(iteratorsize(I1),it
     ((x[1][1],x[1][2]...), x[2])
 end
 
+prod_iteratorsize(::IsScalar, ::IsScalar) = IsScalar()
+prod_iteratorsize(::IsScalar, isz::Union{HasLength,HasShape}) = isz
+prod_iteratorsize(isz::Union{HasLength,HasShape}, ::IsScalar) = isz
 prod_iteratorsize(::Union{HasLength,HasShape}, ::Union{HasLength,HasShape}) = HasShape()
 # products can have an infinite iterator
 prod_iteratorsize(::IsInfinite, ::IsInfinite) = IsInfinite()

base/tuple.jl

@@ -12,6 +12,8 @@ getindex(t::Tuple, b::AbstractArray{Bool}) = getindex(t,find(b))
 
 ## iterating ##
 
+iteratorsize(::Tuple) = HasLength()
+
 start(t::Tuple) = 1
 done(t::Tuple, i::Int) = (length(t) < i)
 next(t::Tuple, i::Int) = (t[i], i+1)