Extend sparse broadcast! to combinations of broadcast scalars and sparse vectors/matrices.

Makes broadcast! dispatch on container type (as broadcast), and inject generic sparse broadcast! for the appropriate container type.

Author: Sacha0

base/broadcast.jl

@@ -202,7 +202,9 @@ Note that `dest` is only used to store the result, and does not supply
 arguments to `f` unless it is also listed in the `As`,
 as in `broadcast!(f, A, A, B)` to perform `A[:] = broadcast(f, A, B)`.
 """
-@inline function broadcast!{N}(f, C::AbstractArray, A, Bs::Vararg{Any,N})
+@inline broadcast!{N}(f, C::AbstractArray, A, Bs::Vararg{Any,N}) =
+    broadcast_c!(f, containertype(C, A, Bs...), C, A, Bs...)
+@inline function broadcast_c!{N}(f, ::Type, C::AbstractArray, A, Bs::Vararg{Any,N})
     shape = indices(C)
     @boundscheck check_broadcast_indices(shape, A, Bs...)
     keeps, Idefaults = map_newindexer(shape, A, Bs)

base/sparse/higherorderfns.jl

@@ -5,7 +5,8 @@ module HigherOrderFns
 # This module provides higher order functions specialized for sparse arrays,
 # particularly map[!]/broadcast[!] for SparseVectors and SparseMatrixCSCs at present.
 import Base: map, map!, broadcast, broadcast!
-import Base.Broadcast: containertype, promote_containertype, broadcast_indices, broadcast_c
+import Base.Broadcast: containertype, promote_containertype,
+    broadcast_indices, broadcast_c, broadcast_c!
 
 using Base: front, tail, to_shape
 using ..SparseArrays: SparseVector, SparseMatrixCSC, AbstractSparseArray, indtype
@@ -852,11 +853,15 @@ promote_containertype(::Type{Tuple}, ::Type{AbstractSparseArray}) = Array
 promote_containertype(::Type{AbstractSparseArray}, ::Type{Array}) = Array
 promote_containertype(::Type{AbstractSparseArray}, ::Type{Tuple}) = Array
 
-# broadcast entry point for combinations of sparse arrays and other types
-function broadcast_c(f, ::Type{AbstractSparseArray}, mixedargs...)
+# broadcast[!] entry points for combinations of sparse arrays and other types
+@inline function broadcast_c{N}(f, ::Type{AbstractSparseArray}, mixedargs::Vararg{Any,N})
     parevalf, passedargstup = capturescalars(f, mixedargs)
     return broadcast(parevalf, passedargstup...)
 end
+@inline function broadcast_c!{N}(f, ::Type{AbstractSparseArray}, dest::SparseVecOrMat, mixedsrcargs::Vararg{Any,N})
+    parevalf, passedsrcargstup = capturescalars(f, mixedsrcargs)
+    return broadcast!(parevalf, dest, passedsrcargstup...)
+end
 # capturescalars takes a function (f) and a tuple of mixed sparse vectors/matrices and
 # broadcast scalar arguments (mixedargs), and returns a function (parevalf) and a reduced
 # argument tuple (passedargstup) containing only the sparse vectors/matrices in mixedargs