More missing functionality

src/ITensors.jl

@@ -1,24 +1,26 @@
 module ITensors
 
 using TensorAlgebra: contract
-using ITensorBase: ITensor, Index, addtags, tags
+using ITensorBase: ITensor, Index, addtags, prime, tags
+
+# Quirks, decide where or if to define.
+using ITensorBase: dag, dim, hasqns, inds, itensor
+
 include("SiteTypes/SiteTypes.jl")
 using .SiteTypes: SiteTypes
 include("LazyApply/LazyApply.jl")
 using .LazyApply: LazyApply
 include("Ops/Ops.jl")
 using .Ops: Ops
 
-# Quirks, decide where or if to define.
-using ITensorBase: dag, dim, hasqns
-
 # TODO: Used in `ITensorMPS.jl`, define in `BackendSelection.jl`.
 struct Algorithm{algname} end
 macro Algorithm_str(algname)
   return :(Algorithm{$(Expr(:quote, Symbol(algname)))})
 end
 
 # TODO: Used in `ITensorMPS.jl`, decide where or if to define it.
+# Maybe define in `TensorAlgebra.jl`.
 function outer end
 
 # TODO: Used in `ITensorMPS.jl`, decide where or if to define it.
@@ -27,34 +29,37 @@ struct Apply{Args}
 end
 
 # TODO: Used in `ITensorMPS.jl`, decide where or if to define it.
+# Probably define in `ITensorBase.jl` as a shorthand for
+# constructing a set of tags.
 macro ts_str(tags) end
 
 # TODO: Used in `ITensorMPS.jl`, decide where or if to define it.
 struct OneITensor end
 
 # TODO: Used in `ITensorMPS.jl`, define in `ITensorBase.jl`.
-# function addtags end
-function addtags! end
 function commonind end
 function commoninds end
 function noprime end
-function noprime! end
-function prime end
-function prime! end
 function removetags end
-function removetags! end
 function replaceprime end
-function replaceprime! end
 function replacetags end
-function replacetags! end
 function setprime end
-function setprime! end
 function settags end
-function settags! end
 function sim end
 function swapprime end
-function swapprime! end
 function uniqueind end
 function uniqueinds end
 
+# TODO: Delete these in-place versions, only define
+# them in `ITensorMPS.jl`.
+function addtags! end
+function noprime! end
+function prime! end
+function removetags! end
+function replaceprime! end
+function replacetags! end
+function setprime! end
+function settags! end
+function swapprime! end
+
 end

src/SiteTypes/sitetype.jl

@@ -194,6 +194,10 @@ end
 
 _sitetypes(i::Index) = _sitetypes(tags(i))
 
+function commontags(i::Index...)
+  return union(tags.(i)...)
+end
+
 """
     op(opname::String, s::Index; kwargs...)