[NDTensors] Fix zero for EmptyStorage

NDTensors/src/NDTensors.jl

@@ -44,6 +44,8 @@ include("abstractarray/ndims.jl")
 include("abstractarray/fill.jl")
 include("array/set_types.jl")
 include("tupletools.jl")
+include("emptynumber.jl")
+include("nodata.jl")
 include("tensorstorage/tensorstorage.jl")
 include("tensorstorage/set_types.jl")
 include("tensorstorage/default_storage.jl")

NDTensors/src/empty/EmptyTensor.jl

@@ -55,7 +55,7 @@ end
 getindex(T::EmptyTensor, I::Integer...) = zero(eltype(T))
 
 function getindex(T::EmptyTensor{Complex{EmptyNumber}}, I::Integer...)
-  return Complex(NDTensors.EmptyNumber(), NDTensors.EmptyNumber())
+  return Complex(EmptyNumber(), EmptyNumber())
 end
 
 similar(T::EmptyTensor, inds::Tuple) = setinds(T, inds)

NDTensors/src/empty/empty.jl

@@ -5,37 +5,6 @@
 
 struct EmptyOrder end
 
-#
-# Represents a number that can be set to any type.
-#
-
-struct EmptyNumber <: Real end
-
-zero(::Type{EmptyNumber}) = EmptyNumber()
-zero(n::EmptyNumber) = zero(typeof(n))
-
-# This helps handle a lot of basic algebra, like:
-# EmptyNumber() + 2.3 == 2.3
-convert(::Type{T}, x::EmptyNumber) where {T<:Number} = T(zero(T))
-
-# TODO: Should this be implemented?
-#Complex(x::Real, ::EmptyNumber) = x
-
-# This is to help define `float(::EmptyNumber) = 0.0`.
-# This helps with defining `norm` of `EmptyStorage{EmptyNumber}`.
-AbstractFloat(::NDTensors.EmptyNumber) = zero(AbstractFloat)
-
-# Basic arithmetic
-(::EmptyNumber + ::EmptyNumber) = EmptyNumber()
-(::EmptyNumber - ::EmptyNumber) = EmptyNumber()
-(::Number * ::EmptyNumber) = EmptyNumber()
-(::EmptyNumber * ::Number) = EmptyNumber()
-(::EmptyNumber * ::EmptyNumber) = EmptyNumber()
-(::EmptyNumber / ::Number) = EmptyNumber()
-(::Number / ::EmptyNumber) = throw(DivideError())
-(::EmptyNumber / ::EmptyNumber) = throw(DivideError())
--(::EmptyNumber) = EmptyNumber()
-
 function similartype(StoreT::Type{<:TensorStorage{EmptyNumber}}, ElT::Type)
   return set_eltype(StoreT, ElT)
 end

NDTensors/src/emptynumber.jl

@@ -0,0 +1,30 @@
+#
+# Represents a number that can be set to any type.
+#
+
+struct EmptyNumber <: Real end
+
+zero(::Type{EmptyNumber}) = EmptyNumber()
+zero(n::EmptyNumber) = zero(typeof(n))
+
+# This helps handle a lot of basic algebra, like:
+# EmptyNumber() + 2.3 == 2.3
+convert(::Type{T}, x::EmptyNumber) where {T<:Number} = T(zero(T))
+
+# TODO: Should this be implemented?
+#Complex(x::Real, ::EmptyNumber) = x
+
+# This is to help define `float(::EmptyNumber) = 0.0`.
+# This helps with defining `norm` of `EmptyStorage{EmptyNumber}`.
+AbstractFloat(::EmptyNumber) = zero(AbstractFloat)
+
+# Basic arithmetic
+(::EmptyNumber + ::EmptyNumber) = EmptyNumber()
+(::EmptyNumber - ::EmptyNumber) = EmptyNumber()
+(::Number * ::EmptyNumber) = EmptyNumber()
+(::EmptyNumber * ::Number) = EmptyNumber()
+(::EmptyNumber * ::EmptyNumber) = EmptyNumber()
+(::EmptyNumber / ::Number) = EmptyNumber()
+(::Number / ::EmptyNumber) = throw(DivideError())
+(::EmptyNumber / ::EmptyNumber) = throw(DivideError())
+-(::EmptyNumber) = EmptyNumber()

NDTensors/src/nodata.jl

@@ -0,0 +1,6 @@
+# Denotes when a storage type has no data
+struct NoData end
+
+size(::NoData) = (0,)
+length(::NoData) = 0
+fill!(::NoData, ::EmptyNumber) = NoData()

NDTensors/src/tensorstorage/tensorstorage.jl

@@ -1,11 +1,5 @@
 abstract type TensorStorage{ElT} <: AbstractVector{ElT} end
 
-# Denotes when a storage type has no data
-struct NoData end
-
-size(::NoData) = (0,)
-length(::NoData) = 0
-
 data(S::TensorStorage) = S.data
 
 datatype(::Type{<:TensorStorage}) = error("Not implemented")

NDTensors/test/emptystorage.jl

@@ -23,5 +23,11 @@ using Test
     @test blockoffsets(T) == BlockOffsets{2}()
     T = dev(EmptyBlockSparseTensor(Float64, ([1, 1], [1, 1])))
     @test blockoffsets(T) == BlockOffsets{2}()
+
+    T = dev(EmptyStorage(NDTensors.EmptyNumber))
+    @test zero(T) isa typeof(T)
+
+    T = dev(EmptyTensor(NDTensors.EmptyNumber, (2, 2)))
+    @test zero(T) isa typeof(T)
   end
 end

test/base/test_emptyitensor.jl

@@ -94,4 +94,10 @@ end
   @test blockoffsets(A) == NDTensors.BlockOffsets{2}()
 end
 
+@testset "zero" for space in (2, [QN(0) => 1, QN(1) => 1])
+  i = Index(space)
+  A = ITensor(i', dag(i))
+  @test NDTensors.tensor(zero(A)) isa typeof(NDTensors.tensor(A))
+end
+
 nothing