From a5afae3a31db2f68e692e2f199da962f9e3ceb04 Mon Sep 17 00:00:00 2001
From: Justin Lebar <jlebar@google.com>
Date: Mon, 10 Oct 2016 16:26:03 +0000
Subject: [PATCH] [ADT] Add make_pointe{e,r}_iterator.

Reviewers: timshen

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D25418

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283765 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/ADT/iterator.h    | 10 ++++++++
 unittests/ADT/IteratorTest.cpp | 45 +++++++++++++++++++---------------
 2 files changed, 35 insertions(+), 20 deletions(-)

diff --git a/include/llvm/ADT/iterator.h b/include/llvm/ADT/iterator.h
index 30b8ac1dafb..eced5eab523 100644
--- a/include/llvm/ADT/iterator.h
+++ b/include/llvm/ADT/iterator.h
@@ -256,6 +256,11 @@ struct pointee_iterator
   T &operator*() const { return **this->I; }
 };
 
+template <typename WrappedIteratorT>
+pointee_iterator<WrappedIteratorT> make_pointee_iterator(WrappedIteratorT &&I) {
+  return pointee_iterator<WrappedIteratorT>(std::forward<WrappedIteratorT>(I));
+}
+
 template <typename WrappedIteratorT,
           typename T = decltype(&*std::declval<WrappedIteratorT>())>
 class pointer_iterator
@@ -273,6 +278,11 @@ public:
   const T &operator*() const { return Ptr = &*this->I; }
 };
 
+template <typename WrappedIteratorT>
+pointer_iterator<WrappedIteratorT> make_pointer_iterator(WrappedIteratorT &&I) {
+  return pointer_iterator<WrappedIteratorT>(std::forward<WrappedIteratorT>(I));
 }
 
+} // namespace llvm
+
 #endif
diff --git a/unittests/ADT/IteratorTest.cpp b/unittests/ADT/IteratorTest.cpp
index 4f1d81d487d..4f8110b153c 100644
--- a/unittests/ADT/IteratorTest.cpp
+++ b/unittests/ADT/IteratorTest.cpp
@@ -42,19 +42,20 @@ TEST(PointeeIteratorTest, Basic) {
   V.push_back(&arr[2]);
   V.push_back(&arr[3]);
 
-  typedef pointee_iterator<SmallVectorImpl<int *>::const_iterator> test_iterator;
-
-  test_iterator Begin, End;
-  Begin = V.begin();
-  End = test_iterator(V.end());
-
-  test_iterator I = Begin;
+  auto Begin = make_pointee_iterator(V.begin());
+  auto End = make_pointee_iterator(V.end());
+  static_assert(
+      std::is_same<decltype(Begin),
+                   pointee_iterator<SmallVectorImpl<int *>::iterator>>::value,
+      "Wrong type returned by make_pointee_iterator");
+
+  auto I = Begin;
   for (int i = 0; i < 4; ++i) {
     EXPECT_EQ(*V[i], *I);
 
     EXPECT_EQ(I, Begin + i);
     EXPECT_EQ(I, std::next(Begin, i));
-    test_iterator J = Begin;
+    auto J = Begin;
     J += i;
     EXPECT_EQ(I, J);
     EXPECT_EQ(*V[i], Begin[i]);
@@ -69,7 +70,7 @@ TEST(PointeeIteratorTest, Basic) {
     EXPECT_EQ(i, std::distance(Begin, I));
     EXPECT_EQ(Begin, I - i);
 
-    test_iterator K = I++;
+    auto K = I++;
     EXPECT_EQ(K, std::prev(I));
   }
   EXPECT_EQ(End, I);
@@ -82,20 +83,21 @@ TEST(PointeeIteratorTest, SmartPointer) {
   V.push_back(make_unique<int>(3));
   V.push_back(make_unique<int>(4));
 
-  typedef pointee_iterator<
-      SmallVectorImpl<std::unique_ptr<int>>::const_iterator> test_iterator;
-
-  test_iterator Begin, End;
-  Begin = V.begin();
-  End = test_iterator(V.end());
+  auto Begin = make_pointee_iterator(V.begin());
+  auto End = make_pointee_iterator(V.end());
+  static_assert(
+      std::is_same<decltype(Begin),
+                   pointee_iterator<
+                       SmallVectorImpl<std::unique_ptr<int>>::iterator>>::value,
+      "Wrong type returned by make_pointee_iterator");
 
-  test_iterator I = Begin;
+  auto I = Begin;
   for (int i = 0; i < 4; ++i) {
     EXPECT_EQ(*V[i], *I);
 
     EXPECT_EQ(I, Begin + i);
     EXPECT_EQ(I, std::next(Begin, i));
-    test_iterator J = Begin;
+    auto J = Begin;
     J += i;
     EXPECT_EQ(I, J);
     EXPECT_EQ(*V[i], Begin[i]);
@@ -110,7 +112,7 @@ TEST(PointeeIteratorTest, SmartPointer) {
     EXPECT_EQ(i, std::distance(Begin, I));
     EXPECT_EQ(Begin, I - i);
 
-    test_iterator K = I++;
+    auto K = I++;
     EXPECT_EQ(K, std::prev(I));
   }
   EXPECT_EQ(End, I);
@@ -187,7 +189,10 @@ TEST(FilterIteratorTest, InputIterator) {
 
 TEST(PointerIterator, Basic) {
   int A[] = {1, 2, 3, 4};
-  pointer_iterator<int *> Begin(std::begin(A)), End(std::end(A));
+  auto Begin = make_pointer_iterator(std::begin(A));
+  auto End = make_pointer_iterator(std::end(A));
+  static_assert(std::is_same<decltype(Begin), pointer_iterator<int *>>::value,
+                "Wrong type returned by make_pointer_iterator");
   EXPECT_EQ(A, *Begin);
   ++Begin;
   EXPECT_EQ(A + 1, *Begin);
@@ -201,7 +206,7 @@ TEST(PointerIterator, Basic) {
 
 TEST(PointerIterator, Const) {
   int A[] = {1, 2, 3, 4};
-  const pointer_iterator<int *> Begin(std::begin(A));
+  auto Begin = make_pointer_iterator(std::begin(A));
   EXPECT_EQ(A, *Begin);
   EXPECT_EQ(A + 1, std::next(*Begin, 1));
   EXPECT_EQ(A + 2, std::next(*Begin, 2));
-- 
2.49.0