Add OperatorStyle and GeometryStyle (#352)

* add styles

* start rewrite

* start defining the styles

* implement styles for states and operators and add tests

* add include styles

* fix InfiniteMPO test

* dispatch styles on type and rename IsfiniteStyle to GeometryStyle

* readd Base.isfinite for AbstractMPS, MPO and MPOHamiltonian

* add tests for styles of types

* fix include order

* fix OperatorStyle for MPOHamiltonian

* Add WindowStyle and increase code coverage

* fix test and hopefully also runic

* more tests

* fix other tests

* make GeometryStyle names more descriptive

* implement changes

* remove unnecessary Base.isfinite definitions, because it is already defined for AbstractMPO

* fix braille tests

* addd

* revert unnecessary changes

* update style docs

* fix formatting

* more formatting

---------

Co-authored-by: Lukas Devos <[email protected]>

Author: AFeuerpfeil

src/MPSKit.jl

@@ -97,6 +97,7 @@ include("utility/logging.jl")
 using .IterativeLoggers
 include("utility/iterativesolvers.jl")
 
+include("utility/styles.jl")
 include("utility/periodicarray.jl")
 include("utility/windowarray.jl")
 include("utility/multiline.jl")

src/operators/mpo.jl

@@ -17,6 +17,8 @@ Matrix Product Operator (MPO) acting on a finite tensor product space with a lin
 """
 const FiniteMPO{O} = MPO{O, Vector{O}}
 Base.isfinite(::Type{<:FiniteMPO}) = true
+GeometryStyle(::Type{<:FiniteMPO}) = FiniteChainStyle()
+OperatorStyle(::Type{<:MPO}) = MPOStyle()
 
 function FiniteMPO(Os::AbstractVector{O}) where {O}
     for i in eachindex(Os)[1:(end - 1)]
@@ -37,6 +39,7 @@ Matrix Product Operator (MPO) acting on an infinite tensor product space with a
 """
 const InfiniteMPO{O} = MPO{O, PeriodicVector{O}}
 Base.isfinite(::Type{<:InfiniteMPO}) = false
+GeometryStyle(::Type{<:InfiniteMPO}) = InfiniteChainStyle()
 
 function InfiniteMPO(Os::AbstractVector{O}) where {O}
     for i in eachindex(Os)

src/operators/mpohamiltonian.jl

@@ -31,9 +31,11 @@ operators in a form that is compatible with this constructor.
 struct MPOHamiltonian{TO <: JordanMPOTensor, V <: AbstractVector{TO}} <: AbstractMPO{TO}
     W::V
 end
+OperatorStyle(::Type{<:MPOHamiltonian}) = HamiltonianStyle()
 
 const FiniteMPOHamiltonian{O <: MPOTensor} = MPOHamiltonian{O, Vector{O}}
 Base.isfinite(::Type{<:FiniteMPOHamiltonian}) = true
+GeometryStyle(::Type{<:FiniteMPOHamiltonian}) = FiniteChainStyle()
 
 function FiniteMPOHamiltonian(Ws::AbstractVector{O}) where {O <: MPOTensor}
     for i in eachindex(Ws)[1:(end - 1)]
@@ -45,6 +47,7 @@ end
 
 const InfiniteMPOHamiltonian{O <: MPOTensor} = MPOHamiltonian{O, PeriodicVector{O}}
 Base.isfinite(::Type{<:InfiniteMPOHamiltonian}) = false
+GeometryStyle(::Type{<:InfiniteMPOHamiltonian}) = InfiniteChainStyle()
 
 function InfiniteMPOHamiltonian(Ws::AbstractVector{O}) where {O <: MPOTensor}
     for i in eachindex(Ws)

src/states/abstractmps.jl

@@ -173,6 +173,7 @@ abstract type AbstractFiniteMPS <: AbstractMPS end
 
 Base.eltype(ψ::AbstractMPS) = eltype(typeof(ψ))
 VectorInterface.scalartype(T::Type{<:AbstractMPS}) = scalartype(site_type(T))
+Base.isfinite(ψ::AbstractMPS) = isfinite(typeof(ψ))
 
 function Base.checkbounds(ψ::AbstractMPS, i)
     return Base.checkbounds(Bool, ψ, i) || throw(BoundsError(ψ, i))

src/states/finitemps.jl

@@ -311,7 +311,8 @@ function Base.similar(ψ::FiniteMPS{A, B}) where {A, B}
     return FiniteMPS{A, B}(similar(ψ.ALs), similar(ψ.ARs), similar(ψ.ACs), similar(ψ.Cs))
 end
 
-Base.isfinite(ψ::FiniteMPS) = true
+Base.isfinite(::Type{<:FiniteMPS}) = true
+GeometryStyle(::Type{<:FiniteMPS}) = FiniteChainStyle()
 
 Base.eachindex(ψ::FiniteMPS) = eachindex(ψ.AL)
 Base.eachindex(l::IndexStyle, ψ::FiniteMPS) = eachindex(l, ψ.AL)

src/states/infinitemps.jl

@@ -241,7 +241,8 @@ Base.size(ψ::InfiniteMPS, args...) = size(ψ.AL, args...)
 Base.length(ψ::InfiniteMPS) = length(ψ.AL)
 Base.eltype(ψ::InfiniteMPS) = eltype(typeof(ψ))
 Base.eltype(::Type{<:InfiniteMPS{A}}) where {A} = A
-Base.isfinite(ψ::InfiniteMPS) = false
+Base.isfinite(::Type{<:InfiniteMPS}) = false
+GeometryStyle(::Type{<:InfiniteMPS}) = InfiniteChainStyle()
 
 Base.copy(ψ::InfiniteMPS) = InfiniteMPS(copy(ψ.AL), copy(ψ.AR), copy(ψ.C), copy(ψ.AC))
 function Base.copy!(ψ::InfiniteMPS, ϕ::InfiniteMPS)

src/states/multilinemps.jl

@@ -101,7 +101,7 @@ Base.convert(::Type{InfiniteMPS}, st::MultilineMPS) = only(st)
 Base.eltype(t::MultilineMPS) = eltype(t[1])
 Base.copy!(ψ::MultilineMPS, ϕ::MultilineMPS) = (copy!.(parent(ψ), parent(ϕ)); ψ)
 
-Base.isfinite(ψ::MultilineMPS) = false
+Base.isfinite(::Type{<:MultilineMPS}) = false
 
 for f_space in (:physicalspace, :left_virtualspace, :right_virtualspace)
     @eval $f_space(t::MultilineMPS, i::Int, j::Int) = $f_space(t[i], j)

src/states/quasiparticle_state.jl

@@ -212,6 +212,8 @@ const FiniteQP{S <: FiniteMPS, T1, T2} = QP{S, T1, T2}
 const InfiniteQP{S <: InfiniteMPS, T1, T2} = QP{S, T1, T2}
 const MultilineQP{Q <: QP} = Multiline{Q}
 
+GeometryStyle(::Type{<:QP{S, T1, T2}}) where {S, T1, T2} = GeometryStyle(S)
+
 TensorKit.spacetype(::Union{QP{S}, Type{<:QP{S}}}) where {S} = spacetype(S)
 TensorKit.sectortype(::Union{QP{S}, Type{<:QP{S}}}) where {S} = sectortype(S)
 

src/utility/multiline.jl

@@ -29,6 +29,7 @@ function Base.axes(m::Multiline, i::Int)
         i == 2 ? axes(parent(m)[1], 1) : throw(ArgumentError("Invalid index $i"))
 end
 Base.eachindex(m::Multiline) = CartesianIndices(size(m))
+Base.isfinite(m::Multiline) = isfinite(typeof(m))
 
 eachsite(m::Multiline) = eachsite(first(parent(m)))
 
@@ -54,6 +55,12 @@ function Base.repeat(A::Multiline, rows::Int, cols::Int)
     return Multiline(outer)
 end
 
+# Style
+# ----------------
+
+OperatorStyle(::Type{Multiline{T}}) where {T} = OperatorStyle(T)
+GeometryStyle(::Type{Multiline{T}}) where {T} = GeometryStyle(T)
+
 # VectorInterface
 # ---------------
 VectorInterface.scalartype(::Type{Multiline{T}}) where {T} = scalartype(T)

src/utility/styles.jl

@@ -0,0 +1,37 @@
+"""
+    abstract type OperatorStyle
+    OperatorStyle(x)
+    OperatorStyle(::Type{T})
+
+Trait to describe the operator behavior of the input `x` or type `T`, which can be either
+*   `MPOStyle()`: product of local factors;
+*   `HamiltonianStyle()`: sum of local terms.
+"""
+abstract type OperatorStyle end
+OperatorStyle(x) = OperatorStyle(typeof(x))
+OperatorStyle(T::Type) = throw(MethodError(OperatorStyle, T)) # avoid stackoverflow if not defined
+
+struct MPOStyle <: OperatorStyle end
+struct HamiltonianStyle <: OperatorStyle end
+
+@doc (@doc OperatorStyle) MPOStyle
+@doc (@doc OperatorStyle) HamiltonianStyle
+
+"""
+    abstract type GeometryStyle
+    GeometryStyle(x)
+    GeometryStyle(::Type{T})
+
+Trait to describe the geometry of the input `x` or type `T`, which can be either
+*   `FiniteChainStyle()`: object is defined on a finite chain;
+*   `InfiniteChainStyle()`: object is defined on an infinite chain.
+"""
+abstract type GeometryStyle end
+GeometryStyle(x) = GeometryStyle(typeof(x))
+GeometryStyle(T::Type) = throw(MethodError(GeometryStyle, T)) # avoid stackoverflow if not defined
+
+struct FiniteChainStyle <: GeometryStyle end
+struct InfiniteChainStyle <: GeometryStyle end
+
+@doc (@doc GeometryStyle) FiniteChainStyle
+@doc (@doc GeometryStyle) InfiniteChainStyle