Allow special casing broadcasting based on data (#260)

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "BandedMatrices"
 uuid = "aae01518-5342-5314-be14-df237901396f"
-version = "0.17.2"
+version = "0.17.3"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/banded/BandedMatrix.jl

@@ -814,4 +814,11 @@ function Base.array_summary(io::IO, B::BandedMatrix, inds)
     print(io, " with data ")
     summary(io, B.data)
     print(io, " with indices ", Base.inds2string(inds))
-end
+end
+
+## Broadcast style
+# allow special casing
+
+
+bandedbroadcaststyle(_) = BandedStyle()
+BroadcastStyle(::Type{<:BandedMatrix{<:Any,Dat}}) where Dat = bandedbroadcaststyle(BroadcastStyle(Dat))

src/generic/broadcast.jl

@@ -35,8 +35,8 @@ conjlayout(::Type{<:Complex}, ::M) where M<:AbstractBandedLayout = ConjLayout{M}
 struct BandedStyle <: AbstractArrayStyle{2} end
 BandedStyle(::Val{2}) = BandedStyle()
 BroadcastStyle(::Type{<:AbstractBandedMatrix}) = BandedStyle()
-BroadcastStyle(::Type{<:Adjoint{<:Any,<:AbstractBandedMatrix}}) = BandedStyle()
-BroadcastStyle(::Type{<:Transpose{<:Any,<:AbstractBandedMatrix}}) = BandedStyle()
+BroadcastStyle(::Type{<:Adjoint{<:Any,Mat}}) where Mat<:AbstractBandedMatrix = BroadcastStyle(Mat)
+BroadcastStyle(::Type{<:Transpose{<:Any,Mat}}) where Mat<:AbstractBandedMatrix = BroadcastStyle(Mat)
 BroadcastStyle(::Type{<:SubArray{<:Any,2,<:AbstractBandedMatrix,<:NTuple{2,AbstractUnitRange{Int}}}}) = BandedStyle()
 BroadcastStyle(::DefaultArrayStyle{2}, ::BandedStyle) = BandedStyle()
 BroadcastStyle(::BandedStyle, ::DefaultArrayStyle{2}) = BandedStyle()