From 43fd0df2b7771bf20080e0c1c32a2e1d245125c0 Mon Sep 17 00:00:00 2001
From: Alexander Plavin <alexander@plav.in>
Date: Mon, 18 Mar 2024 11:29:48 +0100
Subject: [PATCH] support datetimes (#38)

---
 Project.toml            | 12 ++++++++++--
 ext/DatesExt.jl         | 16 ++++++++++++++++
 src/InverseFunctions.jl |  4 ++++
 test/test_inverse.jl    | 26 ++++++++++++++++++++------
 4 files changed, 50 insertions(+), 8 deletions(-)
 create mode 100644 ext/DatesExt.jl

diff --git a/Project.toml b/Project.toml
index 6d6c83e..c007d0a 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,15 +1,23 @@
 name = "InverseFunctions"
 uuid = "3587e190-3f89-42d0-90ee-14403ec27112"
-version = "0.1.12"
+version = "0.1.13"
 
 [deps]
+Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
+[weakdeps]
+Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
+
+[extensions]
+DatesExt = "Dates"
+
 [compat]
 julia = "1"
 
 [extras]
+Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
 Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
 
 [targets]
-test = ["Documenter"]
+test = ["Dates", "Documenter"]
diff --git a/ext/DatesExt.jl b/ext/DatesExt.jl
new file mode 100644
index 0000000..38a153f
--- /dev/null
+++ b/ext/DatesExt.jl
@@ -0,0 +1,16 @@
+module DatesExt
+
+using Dates
+import InverseFunctions: inverse
+
+inverse(::typeof(Dates.datetime2epochms)) = Dates.epochms2datetime
+inverse(::typeof(Dates.epochms2datetime)) = Dates.datetime2epochms
+inverse(::typeof(Dates.date2epochdays)) = Dates.epochdays2date
+inverse(::typeof(Dates.epochdays2date)) = Dates.date2epochdays
+
+inverse(::typeof(datetime2unix)) = unix2datetime
+inverse(::typeof(unix2datetime)) = datetime2unix
+inverse(::typeof(datetime2julian)) = julian2datetime
+inverse(::typeof(julian2datetime)) = datetime2julian
+
+end
diff --git a/src/InverseFunctions.jl b/src/InverseFunctions.jl
index 0c5438b..3710fbe 100644
--- a/src/InverseFunctions.jl
+++ b/src/InverseFunctions.jl
@@ -13,4 +13,8 @@ include("inverse.jl")
 include("setinverse.jl")
 include("test.jl")
 
+@static if !isdefined(Base, :get_extension)
+    include("../ext/DatesExt.jl")
+end
+
 end # module
diff --git a/test/test_inverse.jl b/test/test_inverse.jl
index 8d00796..5798127 100644
--- a/test/test_inverse.jl
+++ b/test/test_inverse.jl
@@ -2,6 +2,7 @@
 
 using Test
 using InverseFunctions
+using Dates
 
 
 foo(x) = inv(exp(-x) + 1)
@@ -18,14 +19,13 @@ end
 (f::Bar)(x) = f.A * x
 InverseFunctions.inverse(f::Bar) = Bar(inv(f.A))
 
+@static if VERSION >= v"1.6"
+    _bc_func(f) = Base.Broadcast.BroadcastFunction(f)
+else
+    _bc_func(f) = Base.Fix1(broadcast, f)
+end
 
 @testset "inverse" begin
-    @static if VERSION >= v"1.6"
-        _bc_func(f) = Base.Broadcast.BroadcastFunction(f)
-    else
-        _bc_func(f) = Base.Fix1(broadcast, f)
-    end
-
     f_without_inverse(x) = 1
     @test inverse(f_without_inverse) isa NoInverse
     @test_throws ErrorException inverse(f_without_inverse)(42)
@@ -40,7 +40,9 @@ InverseFunctions.inverse(f::Bar) = Bar(inv(f.A))
     @test @inferred(NoInverse(Complex)) isa NoInverse{Type{Complex}}
 
     InverseFunctions.test_inverse(inverse, log, compare = ===)
+end
 
+@testset "maths" begin
     InverseFunctions.test_inverse(!, false)
 
     x = rand()
@@ -122,3 +124,15 @@ InverseFunctions.inverse(f::Bar) = Bar(inv(f.A))
         InverseFunctions.test_inverse(log ∘ foo, x)
     end
 end
+
+@testset "dates" begin
+    InverseFunctions.test_inverse(Dates.date2epochdays, Date(2020, 1, 2); compare = ===)
+    InverseFunctions.test_inverse(Dates.datetime2epochms, DateTime(2020, 1, 2, 12, 34, 56); compare = ===)
+    InverseFunctions.test_inverse(Dates.epochdays2date, Int64(1234); compare = ===)
+    InverseFunctions.test_inverse(Dates.epochms2datetime, Int64(1234567890); compare = ===)
+
+    InverseFunctions.test_inverse(datetime2unix, DateTime(2020, 1, 2, 12, 34, 56); compare = ===)
+    InverseFunctions.test_inverse(unix2datetime, 1234.56; compare = ===)
+    InverseFunctions.test_inverse(datetime2julian, DateTime(2020, 1, 2, 12, 34, 56); compare = ===)
+    InverseFunctions.test_inverse(julian2datetime, 1234.56; compare = ===)
+end