From 6535c23b27f218f13d0a41490af44da7b110d38a Mon Sep 17 00:00:00 2001
From: Dilum Aluthge <dilum@aluthge.com>
Date: Sat, 9 Jan 2021 22:22:43 -0500
Subject: [PATCH 1/3] Add the public `Dates.periods` function for getting the
 `Vector` of `Period`s that comprise a `CompoundPeriod`

---
 NEWS.md                        | 1 +
 stdlib/Dates/docs/src/index.md | 1 +
 stdlib/Dates/src/periods.jl    | 7 +++++++
 stdlib/Dates/test/periods.jl   | 1 +
 4 files changed, 10 insertions(+)

diff --git a/NEWS.md b/NEWS.md
index 7793ba31b7f24..9f7bcf26866a2 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -68,6 +68,7 @@ Standard library changes
 
 #### Dates
 
+* The `Dates.periods` function can be used to get the `Vector` of `Period`s that comprise a `CompoundPeriod` ([#39169]).
 
 #### Statistics
 
diff --git a/stdlib/Dates/docs/src/index.md b/stdlib/Dates/docs/src/index.md
index 975c08711fc19..9f48b70b8fb5c 100644
--- a/stdlib/Dates/docs/src/index.md
+++ b/stdlib/Dates/docs/src/index.md
@@ -747,6 +747,7 @@ Dates.Period(::Any)
 Dates.CompoundPeriod(::Vector{<:Dates.Period})
 Dates.value
 Dates.default
+Dates.periods
 ```
 
 ### Rounding Functions
diff --git a/stdlib/Dates/src/periods.jl b/stdlib/Dates/src/periods.jl
index 8d81262af19ec..ac59738c560de 100644
--- a/stdlib/Dates/src/periods.jl
+++ b/stdlib/Dates/src/periods.jl
@@ -196,6 +196,13 @@ struct CompoundPeriod <: AbstractTime
     end
 end
 
+"""
+    periods(::CompoundPeriod) -> Vector{Period}
+
+Return the `Vector` of `Period`s that comprise the given `CompoundPeriod`. 
+"""
+periods(x::CompoundPeriod) = x.periods
+
 """
     CompoundPeriod(periods) -> CompoundPeriod
 
diff --git a/stdlib/Dates/test/periods.jl b/stdlib/Dates/test/periods.jl
index f4dd65d0efd2a..81aacd1a9e54b 100644
--- a/stdlib/Dates/test/periods.jl
+++ b/stdlib/Dates/test/periods.jl
@@ -366,6 +366,7 @@ end
     @test isequal(d - h, 2d - 2h - 1d + 1h)
     @test sprint(show, y + m) == string(y + m)
     @test convert(Dates.CompoundPeriod, y) + m == y + m
+    @test Dates.periods(convert(Dates.CompoundPeriod, y)) == convert(Dates.CompoundPeriod, y).periods
 end
 @testset "compound period simplification" begin
     # reduce compound periods into the most basic form

From 523cb35365874e1d8fadc43abb762da1d8598e33 Mon Sep 17 00:00:00 2001
From: Dilum Aluthge <dilum@aluthge.com>
Date: Sun, 10 Jan 2021 21:18:11 -0500
Subject: [PATCH 2/3] Apply suggestions from code review

---
 stdlib/Dates/src/periods.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stdlib/Dates/src/periods.jl b/stdlib/Dates/src/periods.jl
index ac59738c560de..0745ab0352e53 100644
--- a/stdlib/Dates/src/periods.jl
+++ b/stdlib/Dates/src/periods.jl
@@ -197,7 +197,7 @@ struct CompoundPeriod <: AbstractTime
 end
 
 """
-    periods(::CompoundPeriod) -> Vector{Period}
+    Dates.periods(::CompoundPeriod) -> Vector{Period}
 
 Return the `Vector` of `Period`s that comprise the given `CompoundPeriod`. 
 """

From dd8b43e0e94d7289b7c1937379a0121c4d15f2c6 Mon Sep 17 00:00:00 2001
From: Dilum Aluthge <dilum@aluthge.com>
Date: Sun, 10 Jan 2021 21:35:24 -0500
Subject: [PATCH 3/3] Fix whitespace

---
 stdlib/Dates/src/periods.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stdlib/Dates/src/periods.jl b/stdlib/Dates/src/periods.jl
index 0745ab0352e53..2af634bdf104c 100644
--- a/stdlib/Dates/src/periods.jl
+++ b/stdlib/Dates/src/periods.jl
@@ -199,7 +199,7 @@ end
 """
     Dates.periods(::CompoundPeriod) -> Vector{Period}
 
-Return the `Vector` of `Period`s that comprise the given `CompoundPeriod`. 
+Return the `Vector` of `Period`s that comprise the given `CompoundPeriod`.
 """
 periods(x::CompoundPeriod) = x.periods