From a452029e7df549bea8d02cc34ad33b4331c87267 Mon Sep 17 00:00:00 2001
From: singularitti <singularitti@outlook.com>
Date: Sun, 8 Oct 2023 02:47:01 -0400
Subject: [PATCH 1/3] Add `convert` between `Lattice`s

---
 src/lattice.jl    | 4 ++++
 src/reciprocal.jl | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/src/lattice.jl b/src/lattice.jl
index 857c40c..5211737 100644
--- a/src/lattice.jl
+++ b/src/lattice.jl
@@ -163,3 +163,7 @@ Base.:+(x::Number, lattice::Lattice) = lattice + x
 Base.:-(lattice::Lattice) = -one(eltype(lattice)) * lattice
 Base.:-(lattice::Lattice, x::Number) = Lattice(parent(lattice) .- x)
 Base.:-(x::Number, lattice::Lattice) = -lattice + x
+
+Base.convert(::Type{Lattice{T}}, lattice::Lattice{T}) where {T} = lattice
+Base.convert(::Type{Lattice{T}}, lattice::Lattice{S}) where {S,T} =
+    Lattice(convert(Matrix{T}, parent(lattice)))
diff --git a/src/reciprocal.jl b/src/reciprocal.jl
index ba3b875..278ce13 100644
--- a/src/reciprocal.jl
+++ b/src/reciprocal.jl
@@ -85,3 +85,8 @@ Base.:/(lattice::ReciprocalLattice, x::Number) = ReciprocalLattice(parent(lattic
 Base.:+(lattice::ReciprocalLattice) = lattice
 
 Base.:-(lattice::ReciprocalLattice) = -one(eltype(lattice)) * lattice
+
+Base.convert(::Type{ReciprocalLattice{T}}, lattice::ReciprocalLattice{T}) where {T} =
+    lattice
+Base.convert(::Type{ReciprocalLattice{T}}, lattice::ReciprocalLattice{S}) where {S,T} =
+    ReciprocalLattice(convert(Matrix{T}, parent(lattice)))

From dc1a34fe93558b97f05843275bc2dece355f1113 Mon Sep 17 00:00:00 2001
From: singularitti <singularitti@outlook.com>
Date: Sun, 8 Oct 2023 03:12:07 -0400
Subject: [PATCH 2/3] Add Unitful.jl to `weakdeps`, `UnitfulExt` to
 `extensions`

---
 Project.toml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Project.toml b/Project.toml
index 3cc8ad7..0cbf1fc 100644
--- a/Project.toml
+++ b/Project.toml
@@ -8,6 +8,12 @@ LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"
 StructEquality = "6ec83bb0-ed9f-11e9-3b4c-2b04cb4e219c"
 
+[weakdeps]
+Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
+
+[extensions]
+UnitfulExt = "Unitful"
+
 [compat]
 StaticArrays = "1"
 StructEquality = "1, 2"

From e650e976ba33fa6ac1343007be36befb9a30ae4c Mon Sep 17 00:00:00 2001
From: singularitti <singularitti@outlook.com>
Date: Sun, 8 Oct 2023 03:14:31 -0400
Subject: [PATCH 3/3] Extend `Base.convert`, `uconvert`, `ustrip` for
 `ReciprocalLattice` & `Lattice` in ext/UnitfulExt.jl

---
 ext/UnitfulExt.jl | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 ext/UnitfulExt.jl

diff --git a/ext/UnitfulExt.jl b/ext/UnitfulExt.jl
new file mode 100644
index 0000000..8200e1e
--- /dev/null
+++ b/ext/UnitfulExt.jl
@@ -0,0 +1,40 @@
+module UnitfulExt
+
+using CrystallographyCore: Lattice, ReciprocalLattice
+using Unitful: Quantity, DimensionError, Units, dimension
+
+import Unitful: uconvert, ustrip
+
+# See https://github.com/PainterQubits/Unitful.jl/blob/v1.17.0/src/conversion.jl#L102-L111
+Base.convert(
+    ::Type{Lattice{Quantity{T,D,U}}}, lattice::Lattice{Quantity{T,D,U}}
+) where {T,D,U} = lattice
+Base.convert(
+    ::Type{ReciprocalLattice{Quantity{T,D,U}}}, lattice::ReciprocalLattice{Quantity{T,D,U}}
+) where {T,D,U} = lattice
+function Base.convert(::Type{Lattice{Quantity{T,D,U}}}, lattice::Lattice) where {T,D,U}
+    if dimension(eltype(lattice)) == D
+        return Lattice(map(Base.Fix1(convert, Quantity{T,D,U}), parent(lattice)))
+    else
+        throw(DimensionError(U(), first(lattice)))
+    end
+end
+function Base.convert(
+    ::Type{ReciprocalLattice{Quantity{T,D,U}}}, lattice::ReciprocalLattice
+) where {T,D,U}
+    if dimension(eltype(lattice)) == D
+        return ReciprocalLattice(map(Base.Fix1(convert, Quantity{T,D,U}), parent(lattice)))
+    else
+        throw(DimensionError(U(), first(lattice)))
+    end
+end
+
+# See https://github.com/PainterQubits/Unitful.jl/blob/v1.17.0/src/conversion.jl#L66-L74
+uconvert(u::Units, lattice::Lattice) = Lattice(map(Base.Fix1(uconvert, u), parent(lattice)))
+uconvert(u::Units, lattice::ReciprocalLattice) =
+    ReciprocalLattice(map(Base.Fix1(uconvert, u), parent(lattice)))
+
+ustrip(lattice::Lattice) = Lattice(map(ustrip, parent(lattice)))
+ustrip(lattice::ReciprocalLattice) = ReciprocalLattice(map(ustrip, parent(lattice)))
+
+end