From 4a85ce8546fb708d732ebb1e9c592f87f1938687 Mon Sep 17 00:00:00 2001
From: Elias Carvalho <73039601+eliascarv@users.noreply.github.com>
Date: Wed, 24 Jan 2024 15:53:20 -0300
Subject: [PATCH] Implement Iteration interface and Indexing interface for
 'SequentialTransform' (#6)

---
 src/sequential.jl |  9 +++++++++
 test/runtests.jl  | 17 +++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/src/sequential.jl b/src/sequential.jl
index f72b41b..65579e4 100644
--- a/src/sequential.jl
+++ b/src/sequential.jl
@@ -68,6 +68,15 @@ Create a [`SequentialTransform`](@ref) transform with
 AbstractTrees.nodevalue(::SequentialTransform) = SequentialTransform
 AbstractTrees.children(s::SequentialTransform) = s.transforms
 
+# iteration interface
+Base.length(s::SequentialTransform) = length(s.transforms)
+Base.iterate(s::SequentialTransform, args...) = iterate(s.transforms, args...)
+
+# indexing interface
+Base.getindex(s::SequentialTransform, i) = getindex(s.transforms, i)
+Base.firstindex(s::SequentialTransform) = firstindex(s.transforms)
+Base.lastindex(s::SequentialTransform) = lastindex(s.transforms)
+
 Base.show(io::IO, s::SequentialTransform) = print(io, join(s.transforms, " → "))
 
 function Base.show(io::IO, ::MIME"text/plain", s::SequentialTransform)
diff --git a/test/runtests.jl b/test/runtests.jl
index 7fea00f..262acd4 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -26,4 +26,21 @@ using Test
   T = TestTransform() → TestTransform()
   @test (T → Identity()) == T
   @test (Identity() → T) == T
+
+  # sequential
+  T = TransformsBase.SequentialTransform([TestTransform(), Identity()])
+  # iteration interface
+  @test length(T) == 2
+  T1, state = iterate(T)
+  @test T1 == TestTransform()
+  T2, state = iterate(T, state)
+  @test T2 == Identity()
+  @test isnothing(iterate(T, state))
+  # indexing interface
+  @test T[1] == TestTransform()
+  @test T[2] == Identity()
+  @test firstindex(T) == 1
+  @test lastindex(T) == 2
+  @test T[begin] == TestTransform()
+  @test T[end] == Identity()
 end