Make Adjoint/Transpose behave like typical constructors.

Author: Sacha0

base/linalg/adjtrans.jl

@@ -11,46 +11,42 @@ import Base: length, size, axes, IndexStyle, getindex, setindex!, parent, vec, c
 struct Adjoint{T,S} <: AbstractMatrix{T}
     parent::S
     function Adjoint{T,S}(A::S) where {T,S}
-        checkeltype(Adjoint, T, eltype(A))
+        checkeltype_adjoint(T, eltype(A))
         new(A)
     end
 end
 struct Transpose{T,S} <: AbstractMatrix{T}
     parent::S
     function Transpose{T,S}(A::S) where {T,S}
-        checkeltype(Transpose, T, eltype(A))
+        checkeltype_transpose(T, eltype(A))
         new(A)
     end
 end
 
-function checkeltype(::Type{Transform}, ::Type{ResultEltype}, ::Type{ParentEltype}) where {Transform, ResultEltype, ParentEltype}
-    if ResultEltype !== transformtype(Transform, ParentEltype)
-        error(string("Element type mismatch. Tried to create an `$Transform{$ResultEltype}` ",
-            "from an object with eltype `$ParentEltype`, but the element type of the ",
-            "`$Transform` of an object with eltype `$ParentEltype` must be ",
-            "`$(transformtype(Transform, ParentEltype))`"))
-    end
+function checkeltype_adjoint(::Type{ResultEltype}, ::Type{ParentEltype}) where {ResultEltype,ParentEltype}
+    ResultEltype === Base.promote_op(adjoint, ParentEltype) || error(string(
+        "Element type mismatch. Tried to create an `Adjoint{$ResultEltype}` ",
+        "from an object with eltype `$ParentEltype`, but the element type of ",
+        "the adjoint of an object with eltype `$ParentEltype` must be ",
+        "`$(Base.promote_op(adjoint, ParentEltype))`."))
     return nothing
 end
-function transformtype(::Type{O}, ::Type{S}) where {O,S}
-    # similar to promote_op(::Any, ::Type)
-    @_inline_meta
-    T = _return_type(O, Tuple{_default_type(S)})
-    _isleaftype(S) && return _isleaftype(T) ? T : Any
-    return typejoin(S, T)
+function checkeltype_transpose(::Type{ResultEltype}, ::Type{ParentEltype}) where {ResultEltype,ParentEltype}
+    ResultEltype === Base.promote_op(transpose, ParentEltype) || error(string(
+        "Element type mismatch. Tried to create a `Transpose{$ResultEltype}` ",
+        "from an object with eltype `$ParentEltype`, but the element type of ",
+        "the transpose of an object with eltype `$ParentEltype` must be ",
+        "`$(Base.promote_op(transpose, ParentEltype))`."))
+    return nothing
 end
 
 # basic outer constructors
-Adjoint(A) = Adjoint{transformtype(Adjoint,eltype(A)),typeof(A)}(A)
-Transpose(A) = Transpose{transformtype(Transpose,eltype(A)),typeof(A)}(A)
-
-# numbers are the end of the line
-Adjoint(x::Number) = adjoint(x)
-Transpose(x::Number) = transpose(x)
+Adjoint(A) = Adjoint{Base.promote_op(adjoint,eltype(A)),typeof(A)}(A)
+Transpose(A) = Transpose{Base.promote_op(transpose,eltype(A)),typeof(A)}(A)
 
-# unwrapping constructors
-Adjoint(A::Adjoint) = A.parent
-Transpose(A::Transpose) = A.parent
+# no-op constructors for already-wrapped objects
+Adjoint(A::Adjoint) = A
+Transpose(A::Transpose) = A
 
 # wrapping lowercase quasi-constructors
 adjoint(A::AbstractVecOrMat) = Adjoint(A)
@@ -80,6 +76,7 @@ julia> transpose(A)
 ```
 """
 transpose(A::AbstractVecOrMat) = Transpose(A)
+
 # unwrapping lowercase quasi-constructors
 adjoint(A::Adjoint) = A.parent
 transpose(A::Transpose) = A.parent
@@ -95,10 +92,8 @@ const AdjOrTransAbsVec{T} = AdjOrTrans{T,<:AbstractVector}
 const AdjOrTransAbsMat{T} = AdjOrTrans{T,<:AbstractMatrix}
 
 # for internal use below
-wrappertype(A::Adjoint) = Adjoint
-wrappertype(A::Transpose) = Transpose
-wrappertype(::Type{<:Adjoint}) = Adjoint
-wrappertype(::Type{<:Transpose}) = Transpose
+wrapperop(A::Adjoint) = adjoint
+wrapperop(A::Transpose) = transpose
 
 # AbstractArray interface, basic definitions
 length(A::AdjOrTrans) = length(A.parent)
@@ -108,22 +103,22 @@ axes(v::AdjOrTransAbsVec) = (Base.OneTo(1), axes(v.parent)...)
 axes(A::AdjOrTransAbsMat) = reverse(axes(A.parent))
 IndexStyle(::Type{<:AdjOrTransAbsVec}) = IndexLinear()
 IndexStyle(::Type{<:AdjOrTransAbsMat}) = IndexCartesian()
-@propagate_inbounds getindex(v::AdjOrTransAbsVec, i::Int) = wrappertype(v)(v.parent[i])
-@propagate_inbounds getindex(A::AdjOrTransAbsMat, i::Int, j::Int) = wrappertype(A)(A.parent[j, i])
-@propagate_inbounds setindex!(v::AdjOrTransAbsVec, x, i::Int) = (setindex!(v.parent, wrappertype(v)(x), i); v)
-@propagate_inbounds setindex!(A::AdjOrTransAbsMat, x, i::Int, j::Int) = (setindex!(A.parent, wrappertype(A)(x), j, i); A)
+@propagate_inbounds getindex(v::AdjOrTransAbsVec, i::Int) = wrapperop(v)(v.parent[i])
+@propagate_inbounds getindex(A::AdjOrTransAbsMat, i::Int, j::Int) = wrapperop(A)(A.parent[j, i])
+@propagate_inbounds setindex!(v::AdjOrTransAbsVec, x, i::Int) = (setindex!(v.parent, wrapperop(v)(x), i); v)
+@propagate_inbounds setindex!(A::AdjOrTransAbsMat, x, i::Int, j::Int) = (setindex!(A.parent, wrapperop(A)(x), j, i); A)
 # AbstractArray interface, additional definitions to retain wrapper over vectors where appropriate
-@propagate_inbounds getindex(v::AdjOrTransAbsVec, ::Colon, is::AbstractArray{Int}) = wrappertype(v)(v.parent[is])
-@propagate_inbounds getindex(v::AdjOrTransAbsVec, ::Colon, ::Colon) = wrappertype(v)(v.parent[:])
+@propagate_inbounds getindex(v::AdjOrTransAbsVec, ::Colon, is::AbstractArray{Int}) = wrapperop(v)(v.parent[is])
+@propagate_inbounds getindex(v::AdjOrTransAbsVec, ::Colon, ::Colon) = wrapperop(v)(v.parent[:])
 
 # conversion of underlying storage
 convert(::Type{Adjoint{T,S}}, A::Adjoint) where {T,S} = Adjoint{T,S}(convert(S, A.parent))
 convert(::Type{Transpose{T,S}}, A::Transpose) where {T,S} = Transpose{T,S}(convert(S, A.parent))
 
 # for vectors, the semantics of the wrapped and unwrapped types differ
 # so attempt to maintain both the parent and wrapper type insofar as possible
-similar(A::AdjOrTransAbsVec) = wrappertype(A)(similar(A.parent))
-similar(A::AdjOrTransAbsVec, ::Type{T}) where {T} = wrappertype(A)(similar(A.parent, transformtype(wrappertype(A), T)))
+similar(A::AdjOrTransAbsVec) = wrapperop(A)(similar(A.parent))
+similar(A::AdjOrTransAbsVec, ::Type{T}) where {T} = wrapperop(A)(similar(A.parent, Base.promote_op(wrapperop(A), T)))
 # for matrices, the semantics of the wrapped and unwrapped types are generally the same
 # and as you are allocating with similar anyway, you might as well get something unwrapped
 similar(A::AdjOrTrans) = similar(A.parent, eltype(A), size(A))
@@ -142,30 +137,31 @@ isless(A::AdjOrTransAbsVec, B::AdjOrTransAbsVec) = isless(parent(A), parent(B))
 # to retain the associated semantics post-concatenation
 hcat(avs::Union{Number,AdjointAbsVec}...) = _adjoint_hcat(avs...)
 hcat(tvs::Union{Number,TransposeAbsVec}...) = _transpose_hcat(tvs...)
-_adjoint_hcat(avs::Union{Number,AdjointAbsVec}...) = Adjoint(vcat(map(Adjoint, avs)...))
-_transpose_hcat(tvs::Union{Number,TransposeAbsVec}...) = Transpose(vcat(map(Transpose, tvs)...))
-typed_hcat(::Type{T}, avs::Union{Number,AdjointAbsVec}...) where {T} = Adjoint(typed_vcat(T, map(Adjoint, avs)...))
-typed_hcat(::Type{T}, tvs::Union{Number,TransposeAbsVec}...) where {T} = Transpose(typed_vcat(T, map(Transpose, tvs)...))
+_adjoint_hcat(avs::Union{Number,AdjointAbsVec}...) = adjoint(vcat(map(adjoint, avs)...))
+_transpose_hcat(tvs::Union{Number,TransposeAbsVec}...) = transpose(vcat(map(transpose, tvs)...))
+typed_hcat(::Type{T}, avs::Union{Number,AdjointAbsVec}...) where {T} = adjoint(typed_vcat(T, map(adjoint, avs)...))
+typed_hcat(::Type{T}, tvs::Union{Number,TransposeAbsVec}...) where {T} = transpose(typed_vcat(T, map(transpose, tvs)...))
 # otherwise-redundant definitions necessary to prevent hitting the concat methods in sparse/sparsevector.jl
 hcat(avs::Adjoint{<:Any,<:Vector}...) = _adjoint_hcat(avs...)
 hcat(tvs::Transpose{<:Any,<:Vector}...) = _transpose_hcat(tvs...)
 hcat(avs::Adjoint{T,Vector{T}}...) where {T} = _adjoint_hcat(avs...)
 hcat(tvs::Transpose{T,Vector{T}}...) where {T} = _transpose_hcat(tvs...)
+# TODO unify and allow mixed combinations
 
 
 ### higher order functions
 # preserve Adjoint/Transpose wrapper around vectors
 # to retain the associated semantics post-map/broadcast
 #
 # note that the caller's operation f operates in the domain of the wrapped vectors' entries.
-# hence the Adjoint->f->Adjoint shenanigans applied to the parent vectors' entries.
-map(f, avs::AdjointAbsVec...) = Adjoint(map((xs...) -> Adjoint(f(Adjoint.(xs)...)), parent.(avs)...))
-map(f, tvs::TransposeAbsVec...) = Transpose(map((xs...) -> Transpose(f(Transpose.(xs)...)), parent.(tvs)...))
+# hence the adjoint->f->adjoint shenanigans applied to the parent vectors' entries.
+map(f, avs::AdjointAbsVec...) = adjoint(map((xs...) -> adjoint(f(adjoint.(xs)...)), parent.(avs)...))
+map(f, tvs::TransposeAbsVec...) = transpose(map((xs...) -> transpose(f(transpose.(xs)...)), parent.(tvs)...))
 quasiparentt(x) = parent(x); quasiparentt(x::Number) = x # to handle numbers in the defs below
 quasiparenta(x) = parent(x); quasiparenta(x::Number) = conj(x) # to handle numbers in the defs below
-broadcast(f, avs::Union{Number,AdjointAbsVec}...) = Adjoint(broadcast((xs...) -> Adjoint(f(Adjoint.(xs)...)), quasiparenta.(avs)...))
-broadcast(f, tvs::Union{Number,TransposeAbsVec}...) = Transpose(broadcast((xs...) -> Transpose(f(Transpose.(xs)...)), quasiparentt.(tvs)...))
-
+broadcast(f, avs::Union{Number,AdjointAbsVec}...) = adjoint(broadcast((xs...) -> adjoint(f(adjoint.(xs)...)), quasiparenta.(avs)...))
+broadcast(f, tvs::Union{Number,TransposeAbsVec}...) = transpose(broadcast((xs...) -> transpose(f(transpose.(xs)...)), quasiparentt.(tvs)...))
+# TODO unify and allow mixed combinations
 
 ### linear algebra
 
@@ -186,11 +182,11 @@ end
 *(u::TransposeAbsVec, v::TransposeAbsVec) = throw(MethodError(*, (u, v)))
 
 # Adjoint/Transpose-vector * matrix
-*(u::AdjointAbsVec, A::AbstractMatrix) = Adjoint(Adjoint(A) * u.parent)
-*(u::TransposeAbsVec, A::AbstractMatrix) = Transpose(Transpose(A) * u.parent)
+*(u::AdjointAbsVec, A::AbstractMatrix) = adjoint(adjoint(A) * u.parent)
+*(u::TransposeAbsVec, A::AbstractMatrix) = transpose(transpose(A) * u.parent)
 # Adjoint/Transpose-vector * Adjoint/Transpose-matrix
-*(u::AdjointAbsVec, A::Adjoint{<:Any,<:AbstractMatrix}) = Adjoint(A.parent * u.parent)
-*(u::TransposeAbsVec, A::Transpose{<:Any,<:AbstractMatrix}) = Transpose(A.parent * u.parent)
+*(u::AdjointAbsVec, A::Adjoint{<:Any,<:AbstractMatrix}) = adjoint(A.parent * u.parent)
+*(u::TransposeAbsVec, A::Transpose{<:Any,<:AbstractMatrix}) = transpose(A.parent * u.parent)
 
 
 ## pseudoinversion
@@ -203,10 +199,10 @@ pinv(v::TransposeAbsVec, tol::Real = 0) = pinv(conj(v.parent)).parent
 
 
 ## right-division \
-/(u::AdjointAbsVec, A::AbstractMatrix) = Adjoint(Adjoint(A) \ u.parent)
-/(u::TransposeAbsVec, A::AbstractMatrix) = Transpose(Transpose(A) \ u.parent)
-/(u::AdjointAbsVec, A::Transpose{<:Any,<:AbstractMatrix}) = Adjoint(conj(A.parent) \ u.parent) # technically should be Adjoint(copy(Adjoint(copy(A))) \ u.parent)
-/(u::TransposeAbsVec, A::Adjoint{<:Any,<:AbstractMatrix}) = Transpose(conj(A.parent) \ u.parent) # technically should be Transpose(copy(Transpose(copy(A))) \ u.parent)
+/(u::AdjointAbsVec, A::AbstractMatrix) = adjoint(adjoint(A) \ u.parent)
+/(u::TransposeAbsVec, A::AbstractMatrix) = transpose(transpose(A) \ u.parent)
+/(u::AdjointAbsVec, A::Transpose{<:Any,<:AbstractMatrix}) = adjoint(conj(A.parent) \ u.parent) # technically should be adjoint(copy(adjoint(copy(A))) \ u.parent)
+/(u::TransposeAbsVec, A::Adjoint{<:Any,<:AbstractMatrix}) = transpose(conj(A.parent) \ u.parent) # technically should be transpose(copy(transpose(copy(A))) \ u.parent)
 
 # dismabiguation methods
 *(A::AdjointAbsVec, B::Transpose{<:Any,<:AbstractMatrix}) = A * copy(B)

test/linalg/adjtrans.jl

@@ -62,23 +62,12 @@ end
     # the tests for the inner constructors exercise abstract scalar and concrete array eltype, forgoing here
 end
 
-@testset "Adjoint and Transpose of Numbers" begin
-    @test Adjoint(1) == 1
-    @test Adjoint(1.0) == 1.0
-    @test Adjoint(1im) == -1im
-    @test Adjoint(1.0im) == -1.0im
-    @test Transpose(1) == 1
-    @test Transpose(1.0) == 1.0
-    @test Transpose(1im) == 1im
-    @test Transpose(1.0im) == 1.0im
-end
-
-@testset "Adjoint and Transpose unwrapping" begin
+@testset "Adjoint and Transpose no-op on already-wrapped objects" begin
     intvec, intmat = [1, 2], [1 2; 3 4]
-    @test Adjoint(Adjoint(intvec)) === intvec
-    @test Adjoint(Adjoint(intmat)) === intmat
-    @test Transpose(Transpose(intvec)) === intvec
-    @test Transpose(Transpose(intmat)) === intmat
+    @test (A = Adjoint(intvec); Adjoint(A) === A)
+    @test (A = Adjoint(intmat); Adjoint(A) === A)
+    @test (A = Transpose(intvec); Transpose(A) === A)
+    @test (A = Transpose(intmat); Transpose(A) === A)
 end
 
 @testset "Adjoint and Transpose basic AbstractArray functionality" begin
@@ -441,6 +430,17 @@ end
     end
 end
 
+@testset "adjoint and transpose of Numbers" begin
+    @test adjoint(1) == 1
+    @test adjoint(1.0) == 1.0
+    @test adjoint(1im) == -1im
+    @test adjoint(1.0im) == -1.0im
+    @test transpose(1) == 1
+    @test transpose(1.0) == 1.0
+    @test transpose(1im) == 1im
+    @test transpose(1.0im) == 1.0im
+end
+
 @testset "adjoint!(a, b) return a" begin
     a = fill(1.0+im, 5)
     b = fill(1.0+im, 1, 5)