Simplifications

Author: mtfishman

ext/QuantumOperatorDefinitionsITensorBaseExt/QuantumOperatorDefinitionsITensorBaseExt.jl

@@ -8,29 +8,18 @@ using QuantumOperatorDefinitions:
 function QuantumOperatorDefinitions.SiteType(r::Index)
   # We pass the axis of the (unnamed) Index because
   # the Index may have originated from a slice, in which
-  # case the start may not be 1 (and it may not even
+  # case the start may not be 1 (for NonContiguousIndex,
+  # which we need to add support for, it may not even
   # be a unit range).
   return SiteType(
     gettag(r, "sitetype", "Qudit"); dim=Int.(length(r)), range=only(axes(dename(r)))
   )
 end
 
-function ITensorBase.Index(t::SiteType; kwargs...)
-  return Index(AbstractUnitRange(t); kwargs...)
-end
-
+# TODO: Define in terms of `OpName` directly, and define a generic
+# forwarding method `has_fermion_string(n::String, t) = has_fermion_string(OpName(n), t)`.
 function QuantumOperatorDefinitions.has_fermion_string(n::String, r::Index)
   return has_fermion_string(OpName(n), SiteType(r))
 end
 
-function Base.AbstractArray(n::OpName, r::Index)
-  # TODO: Define this with mapped dimnames.
-  # Generalize beyond prime levels with codomain and domain indices.
-  return ITensor(AbstractArray(n, SiteType(r)), (prime(r), dag(r)))
-end
-
-function Base.AbstractArray(n::StateName, r::Index)
-  return ITensor(AbstractArray(n, SiteType(r)), (r,))
-end
-
 end

src/sitetype.jl

@@ -66,6 +66,9 @@ function Base.length(t::SiteType)
   end
   return length(t′)
 end
+# TODO: Use a shorthand `(t::SiteType)() = AbstractUnitRange(t)`,
+# i.e. make `SiteType` callable like `OpName` and `StateName`
+# are right now.
 function Base.AbstractUnitRange(t::SiteType)
   # This logic allows specifying a range with extra properties,
   # like ones with symmetry sectors.
@@ -76,6 +79,10 @@ function Base.AbstractUnitRange(t::SiteType)
   end
   return Base.OneTo(length(t))
 end
+# kwargs are passed for fancier constructors, like `ITensors.Index`.
+function (rangetype::Type{<:AbstractUnitRange})(t::SiteType; kwargs...)
+  return rangetype(AbstractUnitRange(t); kwargs...)
+end
 Base.size(t::SiteType) = (length(t),)
 Base.size(t::SiteType, dim::Integer) = size(t)[dim]
 Base.axes(t::SiteType) = (AbstractUnitRange(t),)