From c0a2e51a78e16f2b0d32f132a56318a3f72eb7fc Mon Sep 17 00:00:00 2001
From: Joachim Brand <joachim.brand@gmail.com>
Date: Sun, 2 Feb 2025 02:02:08 +1300
Subject: [PATCH] sparse constructors

---
 src/BitStringAddresses/bosefs.jl             |  1 +
 src/BitStringAddresses/fermifs.jl            |  6 ++++--
 src/BitStringAddresses/occupationnumberfs.jl | 18 ++++++++++++++++--
 test/BitStringAddresses.jl                   |  9 ++++++++-
 4 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/src/BitStringAddresses/bosefs.jl b/src/BitStringAddresses/bosefs.jl
index 0d0433c89..8ac94c04e 100644
--- a/src/BitStringAddresses/bosefs.jl
+++ b/src/BitStringAddresses/bosefs.jl
@@ -107,6 +107,7 @@ BoseFS(vals::Integer...) = BoseFS(vals) # specify occupation numbers
 BoseFS(val::Integer) = BoseFS((val,)) # single mode address
 BoseFS{N,M}(vals::Integer...) where {N,M} = BoseFS{N,M}(vals)
 
+# Sparse constructors
 BoseFS(M::Integer, pairs::Pair...) = BoseFS(M, pairs)
 BoseFS(M::Integer, pairs) = BoseFS(sparse_to_onr(M, pairs))
 BoseFS{N,M}(pairs::Pair...) where {N,M} = BoseFS{N,M}(pairs)
diff --git a/src/BitStringAddresses/fermifs.jl b/src/BitStringAddresses/fermifs.jl
index 43f9dc3a6..94a548292 100644
--- a/src/BitStringAddresses/fermifs.jl
+++ b/src/BitStringAddresses/fermifs.jl
@@ -24,7 +24,7 @@ chosen automatically based on the properties of the address.
   particles in `bs` is equal to `N`, or whether each mode only contains one particle.
 
 * [`@fs_str`](@ref): Addresses are sometimes printed in a compact manner. This
-  representation can also be used as a constructor. See the last example below.
+  representation can also be used as a constructor. See the examples below.
 
 # Examples
 
@@ -95,7 +95,8 @@ function FermiFS{N,M}(onr::Union{AbstractArray{<:Integer},NTuple{M,<:Integer}})
     end
     return FermiFS{N,M,S}(from_fermi_onr(S, onr))
 end
-function FermiFS(onr::Union{AbstractArray,Tuple})
+function FermiFS(onr)
+    onr = Tuple(onr)
     M = length(onr)
     N = sum(onr)
     return FermiFS{N,M}(onr)
@@ -109,6 +110,7 @@ FermiFS(M::Integer, pairs::Pair...) = FermiFS(M, pairs)
 FermiFS(M::Integer, pairs) = FermiFS(sparse_to_onr(M, pairs))
 FermiFS{N,M}(pairs::Vararg{Pair,N}) where {N,M} = FermiFS{N,M}(pairs)
 FermiFS{N,M}(pairs) where {N,M} = FermiFS{N,M}(sparse_to_onr(M, pairs))
+FermiFS(pairs::Pair...) = throw(ArgumentError("number of modes must be provided"))
 
 function print_address(io::IO, f::FermiFS{N,M}; compact=false) where {N,M}
     if compact && f.bs isa SortedParticleList
diff --git a/src/BitStringAddresses/occupationnumberfs.jl b/src/BitStringAddresses/occupationnumberfs.jl
index d3ce4089f..f2cf880f9 100644
--- a/src/BitStringAddresses/occupationnumberfs.jl
+++ b/src/BitStringAddresses/occupationnumberfs.jl
@@ -32,6 +32,9 @@ OccupationNumberFS{5, UInt8}(0, 0, 0, 0, 0)
 
 julia> OccupationNumberFS(i for i in 1:3) # use list comprehension
 OccupationNumberFS{3, UInt8}(1, 2, 3)
+
+julia> OccupationNumberFS(4, 1=>2, 3=>4) # sparse constructor
+OccupationNumberFS{4, UInt8}(2, 0, 4, 0)
 ```
 """
 struct OccupationNumberFS{M,T<:Unsigned} <: SingleComponentFockAddress{missing,M}
@@ -51,9 +54,10 @@ function OccupationNumberFS(arg)
     return OccupationNumberFS{length(t)}(t)
 end
 
-function OccupationNumberFS(args...)
+function OccupationNumberFS(args::Integer...)
     return OccupationNumberFS{length(args)}(args)
 end
+OccupationNumberFS(arg::Integer) = OccupationNumberFS{1}(arg) # to resolve ambiguity
 
 function OccupationNumberFS{M}(args...) where M
     sv = SVector{M}(args...)
@@ -71,9 +75,19 @@ end
 function OccupationNumberFS{M,T}() where {M,T<:Unsigned}
     return OccupationNumberFS(SVector{M,T}(zero(T) for _ in 1:M))
 end
-
 OccupationNumberFS{M}() where {M} = OccupationNumberFS{M,UInt8}()
 
+# Sparse constructors
+OccupationNumberFS(M::Integer, pairs::Pair...) = OccupationNumberFS(M, pairs)
+OccupationNumberFS(M::Integer, pairs) = OccupationNumberFS(sparse_to_onr(M, pairs))
+OccupationNumberFS{M}(pairs::Pair...) where {M} = OccupationNumberFS{M}(pairs)
+
+function OccupationNumberFS{M}(pairs::NTuple{<:Any,Pair}) where {M}
+    OccupationNumberFS{M}(sparse_to_onr(M, pairs))
+end
+
+OccupationNumberFS(pairs::Pair...) = throw(ArgumentError("number of modes must be provided"))
+
 function print_address(io::IO, ofs::OccupationNumberFS{M,T}; compact=false) where {M,T}
     if compact
         BITS = sizeof(T) * 8
diff --git a/test/BitStringAddresses.jl b/test/BitStringAddresses.jl
index cc4e29da2..8dde7aaaf 100644
--- a/test/BitStringAddresses.jl
+++ b/test/BitStringAddresses.jl
@@ -464,7 +464,7 @@ end
         @test OccupationNumberFS(i for i in 1:3) == OccupationNumberFS(1, 2, 3)
         @test isa(OccupationNumberFS{3,UInt32}(i for i in 1:3), OccupationNumberFS{3,UInt32})
         @test isa(OccupationNumberFS(1, 2, 3), OccupationNumberFS{3,UInt8})
-        @test_throws ArgumentError OccupationNumberFS(1.1, 2, 3)
+        @test_throws MethodError OccupationNumberFS(1.1, 2, 3)
         @test_throws ArgumentError OccupationNumberFS(-1, 2, 3)
         @test_throws ArgumentError OccupationNumberFS(1, 2, 300)
     end
@@ -485,6 +485,13 @@ end
         @test isa(OccupationNumberFS(fs), OccupationNumberFS{2,UInt8})
     end
 
+    @testset "OccupationNumberFS with sparse constructor" begin
+        @test OccupationNumberFS(2, 2=>4) == OccupationNumberFS(0, 4)
+        @test OccupationNumberFS{2}(2 => 4) == OccupationNumberFS(2, 2 => 4)
+        @test OccupationNumberFS(5, i => i + 1 for i in 1:3) ==
+            OccupationNumberFS{5}(Tuple(i => i + 1 for i in 1:3))
+    end
+
     @testset "Printing and parsing OccupationNumberFS" begin
         fs = OccupationNumberFS(1, 2, 3, 0, 1, 20, 3, 2, 5, 0, 1)
         @test eval(Meta.parse(repr(fs))) == fs