Move ArrayRef to runtime/base

Will be used in upcoming CLs regarding VDEX and VerifierDeps.

Test: m test-art-host
Change-Id: I68e611a4a52246c2bdf45eab7c61f3212908afd4
diff --git a/runtime/base/transform_iterator_test.cc b/runtime/base/transform_iterator_test.cc
new file mode 100644
index 0000000..a85dda8
--- /dev/null
+++ b/runtime/base/transform_iterator_test.cc
@@ -0,0 +1,531 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <algorithm>
+#include <forward_list>
+#include <list>
+#include <type_traits>
+#include <vector>
+
+#include "gtest/gtest.h"
+
+#include "base/transform_iterator.h"
+
+namespace art {
+
+namespace {  // anonymous namespace
+
+struct ValueHolder {
+  // Deliberately not explicit.
+  ValueHolder(int v) : value(v) { }  // NOLINT
+  int value;
+};
+
+bool operator==(const ValueHolder& lhs, const ValueHolder& rhs) {
+  return lhs.value == rhs.value;
+}
+
+}  // anonymous namespace
+
+TEST(TransformIterator, VectorAdd1) {
+  auto add1 = [](const ValueHolder& h) { return h.value + 1; };  // NOLINT [readability/braces]
+  std::vector<ValueHolder> input({ 1, 7, 3, 8 });
+  std::vector<int> output;
+
+  using vector_titer = decltype(MakeTransformIterator(input.begin(), add1));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_titer::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_titer::value_type>::value, "value_type");
+  static_assert(std::is_same<vector_titer, vector_titer::pointer>::value, "pointer");
+  static_assert(std::is_same<int, vector_titer::reference>::value, "reference");
+
+  using vector_ctiter = decltype(MakeTransformIterator(input.cbegin(), add1));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_ctiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_ctiter::value_type>::value, "value_type");
+  static_assert(std::is_same<vector_ctiter, vector_ctiter::pointer>::value, "pointer");
+  static_assert(std::is_same<int, vector_ctiter::reference>::value, "reference");
+
+  using vector_rtiter = decltype(MakeTransformIterator(input.rbegin(), add1));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_rtiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_rtiter::value_type>::value, "value_type");
+  static_assert(std::is_same<vector_rtiter, vector_rtiter::pointer>::value, "pointer");
+  static_assert(std::is_same<int, vector_rtiter::reference>::value, "reference");
+
+  using vector_crtiter = decltype(MakeTransformIterator(input.crbegin(), add1));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_crtiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_crtiter::value_type>::value, "value_type");
+  static_assert(std::is_same<vector_crtiter, vector_crtiter::pointer>::value, "pointer");
+  static_assert(std::is_same<int, vector_crtiter::reference>::value, "reference");
+
+  std::copy(MakeTransformIterator(input.begin(), add1),
+            MakeTransformIterator(input.end(), add1),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 2, 8, 4, 9 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.cbegin(), add1),
+            MakeTransformIterator(input.cend(), add1),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 2, 8, 4, 9 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.rbegin(), add1),
+            MakeTransformIterator(input.rend(), add1),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 9, 4, 8, 2 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.crbegin(), add1),
+            MakeTransformIterator(input.crend(), add1),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 9, 4, 8, 2 }), output);
+  output.clear();
+
+  for (size_t i = 0; i != input.size(); ++i) {
+    ASSERT_EQ(input[i].value + 1, MakeTransformIterator(input.begin(), add1)[i]);
+    ASSERT_EQ(input[i].value + 1, MakeTransformIterator(input.cbegin(), add1)[i]);
+    ptrdiff_t index_from_rbegin = static_cast<ptrdiff_t>(input.size() - i - 1u);
+    ASSERT_EQ(input[i].value + 1, MakeTransformIterator(input.rbegin(), add1)[index_from_rbegin]);
+    ASSERT_EQ(input[i].value + 1, MakeTransformIterator(input.crbegin(), add1)[index_from_rbegin]);
+    ptrdiff_t index_from_end = -static_cast<ptrdiff_t>(input.size() - i);
+    ASSERT_EQ(input[i].value + 1, MakeTransformIterator(input.end(), add1)[index_from_end]);
+    ASSERT_EQ(input[i].value + 1, MakeTransformIterator(input.cend(), add1)[index_from_end]);
+    ptrdiff_t index_from_rend = -1 - static_cast<ptrdiff_t>(i);
+    ASSERT_EQ(input[i].value + 1, MakeTransformIterator(input.rend(), add1)[index_from_rend]);
+    ASSERT_EQ(input[i].value + 1, MakeTransformIterator(input.crend(), add1)[index_from_rend]);
+
+    ASSERT_EQ(MakeTransformIterator(input.begin(), add1) + i,
+              MakeTransformIterator(input.begin() + i, add1));
+    ASSERT_EQ(MakeTransformIterator(input.cbegin(), add1) + i,
+              MakeTransformIterator(input.cbegin() + i, add1));
+    ASSERT_EQ(MakeTransformIterator(input.rbegin(), add1) + i,
+              MakeTransformIterator(input.rbegin() + i, add1));
+    ASSERT_EQ(MakeTransformIterator(input.crbegin(), add1) + i,
+              MakeTransformIterator(input.crbegin() + i, add1));
+    ASSERT_EQ(MakeTransformIterator(input.end(), add1) - i,
+              MakeTransformIterator(input.end() - i, add1));
+    ASSERT_EQ(MakeTransformIterator(input.cend(), add1) - i,
+              MakeTransformIterator(input.cend() - i, add1));
+    ASSERT_EQ(MakeTransformIterator(input.rend(), add1) - i,
+              MakeTransformIterator(input.rend() - i, add1));
+    ASSERT_EQ(MakeTransformIterator(input.crend(), add1) - i,
+              MakeTransformIterator(input.crend() - i, add1));
+  }
+  ASSERT_EQ(input.end(),
+            (MakeTransformIterator(input.begin(), add1) + input.size()).base());
+  ASSERT_EQ(MakeTransformIterator(input.end(), add1) - MakeTransformIterator(input.begin(), add1),
+            static_cast<ptrdiff_t>(input.size()));
+
+  // Test iterator->const_iterator conversion and comparison.
+  auto it = MakeTransformIterator(input.begin(), add1);
+  decltype(MakeTransformIterator(input.cbegin(), add1)) cit = it;
+  static_assert(!std::is_same<decltype(it), decltype(cit)>::value, "Types must be different");
+  ASSERT_EQ(it, cit);
+  auto rit = MakeTransformIterator(input.rbegin(), add1);
+  decltype(MakeTransformIterator(input.crbegin(), add1)) crit(rit);
+  static_assert(!std::is_same<decltype(rit), decltype(crit)>::value, "Types must be different");
+  ASSERT_EQ(rit, crit);
+}
+
+TEST(TransformIterator, ListSub1) {
+  auto sub1 = [](const ValueHolder& h) { return h.value - 1; };  // NOLINT [readability/braces]
+  std::list<ValueHolder> input({ 2, 3, 5, 7, 11 });
+  std::vector<int> output;
+
+  using list_titer = decltype(MakeTransformIterator(input.begin(), sub1));
+  static_assert(std::is_same<std::bidirectional_iterator_tag,
+                             list_titer::iterator_category>::value, "category");
+  static_assert(std::is_same<int, list_titer::value_type>::value, "value_type");
+  static_assert(std::is_same<list_titer, list_titer::pointer>::value, "pointer");
+  static_assert(std::is_same<int, list_titer::reference>::value, "reference");
+
+  using list_ctiter = decltype(MakeTransformIterator(input.cbegin(), sub1));
+  static_assert(std::is_same<std::bidirectional_iterator_tag,
+                             list_ctiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, list_ctiter::value_type>::value, "value_type");
+  static_assert(std::is_same<list_ctiter, list_ctiter::pointer>::value, "pointer");
+  static_assert(std::is_same<int, list_ctiter::reference>::value, "reference");
+
+  using list_rtiter = decltype(MakeTransformIterator(input.rbegin(), sub1));
+  static_assert(std::is_same<std::bidirectional_iterator_tag,
+                             list_rtiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, list_rtiter::value_type>::value, "value_type");
+  static_assert(std::is_same<list_rtiter, list_rtiter::pointer>::value, "pointer");
+  static_assert(std::is_same<int, list_rtiter::reference>::value, "reference");
+
+  using list_crtiter = decltype(MakeTransformIterator(input.crbegin(), sub1));
+  static_assert(std::is_same<std::bidirectional_iterator_tag,
+                             list_crtiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, list_crtiter::value_type>::value, "value_type");
+  static_assert(std::is_same<list_crtiter, list_crtiter::pointer>::value, "pointer");
+  static_assert(std::is_same<int, list_crtiter::reference>::value, "reference");
+
+  std::copy(MakeTransformIterator(input.begin(), sub1),
+            MakeTransformIterator(input.end(), sub1),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 1, 2, 4, 6, 10 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.cbegin(), sub1),
+            MakeTransformIterator(input.cend(), sub1),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 1, 2, 4, 6, 10 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.rbegin(), sub1),
+            MakeTransformIterator(input.rend(), sub1),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 10, 6, 4, 2, 1 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.crbegin(), sub1),
+            MakeTransformIterator(input.crend(), sub1),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 10, 6, 4, 2, 1  }), output);
+  output.clear();
+
+  // Test iterator->const_iterator conversion and comparison.
+  auto it = MakeTransformIterator(input.begin(), sub1);
+  decltype(MakeTransformIterator(input.cbegin(), sub1)) cit = it;
+  static_assert(!std::is_same<decltype(it), decltype(cit)>::value, "Types must be different");
+  ASSERT_EQ(it, cit);
+}
+
+TEST(TransformIterator, ForwardListSub1) {
+  auto mul3 = [](const ValueHolder& h) { return h.value * 3; };  // NOLINT [readability/braces]
+  std::forward_list<ValueHolder> input({ 1, 1, 2, 3, 5, 8 });
+  std::vector<int> output;
+
+  using flist_titer = decltype(MakeTransformIterator(input.begin(), mul3));
+  static_assert(std::is_same<std::forward_iterator_tag,
+                             flist_titer::iterator_category>::value, "category");
+  static_assert(std::is_same<int, flist_titer::value_type>::value, "value_type");
+  static_assert(std::is_same<flist_titer, flist_titer::pointer>::value, "pointer");
+  static_assert(std::is_same<int, flist_titer::reference>::value, "reference");
+
+  using flist_ctiter = decltype(MakeTransformIterator(input.cbegin(), mul3));
+  static_assert(std::is_same<std::forward_iterator_tag,
+                             flist_ctiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, flist_ctiter::value_type>::value, "value_type");
+  static_assert(std::is_same<flist_ctiter, flist_ctiter::pointer>::value, "pointer");
+  static_assert(std::is_same<int, flist_ctiter::reference>::value, "reference");
+
+  std::copy(MakeTransformIterator(input.begin(), mul3),
+            MakeTransformIterator(input.end(), mul3),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 3, 3, 6, 9, 15, 24 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.cbegin(), mul3),
+            MakeTransformIterator(input.cend(), mul3),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 3, 3, 6, 9, 15, 24 }), output);
+  output.clear();
+
+  // Test iterator->const_iterator conversion and comparison.
+  auto it = MakeTransformIterator(input.begin(), mul3);
+  decltype(MakeTransformIterator(input.cbegin(), mul3)) cit = it;
+  static_assert(!std::is_same<decltype(it), decltype(cit)>::value, "Types must be different");
+  ASSERT_EQ(it, cit);
+}
+
+TEST(TransformIterator, VectorConstReference) {
+  auto ref = [](const ValueHolder& h) -> const int& { return h.value; };  // NOLINT [readability/braces]
+  std::vector<ValueHolder> input({ 7, 3, 1, 2, 4, 8 });
+  std::vector<int> output;
+
+  using vector_titer = decltype(MakeTransformIterator(input.begin(), ref));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_titer::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_titer::value_type>::value, "value_type");
+  static_assert(std::is_same<const int*, vector_titer::pointer>::value, "pointer");
+  static_assert(std::is_same<const int&, vector_titer::reference>::value, "reference");
+
+  using vector_ctiter = decltype(MakeTransformIterator(input.cbegin(), ref));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_ctiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_ctiter::value_type>::value, "value_type");
+  static_assert(std::is_same<const int*, vector_ctiter::pointer>::value, "pointer");
+  static_assert(std::is_same<const int&, vector_ctiter::reference>::value, "reference");
+
+  using vector_rtiter = decltype(MakeTransformIterator(input.rbegin(), ref));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_rtiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_rtiter::value_type>::value, "value_type");
+  static_assert(std::is_same<const int*, vector_rtiter::pointer>::value, "pointer");
+  static_assert(std::is_same<const int&, vector_rtiter::reference>::value, "reference");
+
+  using vector_crtiter = decltype(MakeTransformIterator(input.crbegin(), ref));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_crtiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_crtiter::value_type>::value, "value_type");
+  static_assert(std::is_same<const int*, vector_crtiter::pointer>::value, "pointer");
+  static_assert(std::is_same<const int&, vector_crtiter::reference>::value, "reference");
+
+  std::copy(MakeTransformIterator(input.begin(), ref),
+            MakeTransformIterator(input.end(), ref),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 7, 3, 1, 2, 4, 8 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.cbegin(), ref),
+            MakeTransformIterator(input.cend(), ref),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 7, 3, 1, 2, 4, 8 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.rbegin(), ref),
+            MakeTransformIterator(input.rend(), ref),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 8, 4, 2, 1, 3, 7 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.crbegin(), ref),
+            MakeTransformIterator(input.crend(), ref),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 8, 4, 2, 1, 3, 7 }), output);
+  output.clear();
+
+  for (size_t i = 0; i != input.size(); ++i) {
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.begin(), ref)[i]);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.cbegin(), ref)[i]);
+    ptrdiff_t index_from_rbegin = static_cast<ptrdiff_t>(input.size() - i - 1u);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.rbegin(), ref)[index_from_rbegin]);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.crbegin(), ref)[index_from_rbegin]);
+    ptrdiff_t index_from_end = -static_cast<ptrdiff_t>(input.size() - i);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.end(), ref)[index_from_end]);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.cend(), ref)[index_from_end]);
+    ptrdiff_t index_from_rend = -1 - static_cast<ptrdiff_t>(i);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.rend(), ref)[index_from_rend]);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.crend(), ref)[index_from_rend]);
+
+    ASSERT_EQ(MakeTransformIterator(input.begin(), ref) + i,
+              MakeTransformIterator(input.begin() + i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.cbegin(), ref) + i,
+              MakeTransformIterator(input.cbegin() + i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.rbegin(), ref) + i,
+              MakeTransformIterator(input.rbegin() + i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.crbegin(), ref) + i,
+              MakeTransformIterator(input.crbegin() + i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.end(), ref) - i,
+              MakeTransformIterator(input.end() - i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.cend(), ref) - i,
+              MakeTransformIterator(input.cend() - i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.rend(), ref) - i,
+              MakeTransformIterator(input.rend() - i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.crend(), ref) - i,
+              MakeTransformIterator(input.crend() - i, ref));
+  }
+  ASSERT_EQ(input.end(),
+            (MakeTransformIterator(input.begin(), ref) + input.size()).base());
+  ASSERT_EQ(MakeTransformIterator(input.end(), ref) - MakeTransformIterator(input.begin(), ref),
+            static_cast<ptrdiff_t>(input.size()));
+}
+
+TEST(TransformIterator, VectorNonConstReference) {
+  auto ref = [](ValueHolder& h) -> int& { return h.value; };  // NOLINT [readability/braces]
+  std::vector<ValueHolder> input({ 7, 3, 1, 2, 4, 8 });
+  std::vector<int> output;
+
+  using vector_titer = decltype(MakeTransformIterator(input.begin(), ref));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_titer::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_titer::value_type>::value, "value_type");
+  static_assert(std::is_same<int*, vector_titer::pointer>::value, "pointer");
+  static_assert(std::is_same<int&, vector_titer::reference>::value, "reference");
+
+  using vector_rtiter = decltype(MakeTransformIterator(input.rbegin(), ref));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_rtiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_rtiter::value_type>::value, "value_type");
+  static_assert(std::is_same<int*, vector_rtiter::pointer>::value, "pointer");
+  static_assert(std::is_same<int&, vector_rtiter::reference>::value, "reference");
+
+  std::copy(MakeTransformIterator(input.begin(), ref),
+            MakeTransformIterator(input.end(), ref),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 7, 3, 1, 2, 4, 8 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.rbegin(), ref),
+            MakeTransformIterator(input.rend(), ref),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 8, 4, 2, 1, 3, 7 }), output);
+  output.clear();
+
+  for (size_t i = 0; i != input.size(); ++i) {
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.begin(), ref)[i]);
+    ptrdiff_t index_from_rbegin = static_cast<ptrdiff_t>(input.size() - i - 1u);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.rbegin(), ref)[index_from_rbegin]);
+    ptrdiff_t index_from_end = -static_cast<ptrdiff_t>(input.size() - i);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.end(), ref)[index_from_end]);
+    ptrdiff_t index_from_rend = -1 - static_cast<ptrdiff_t>(i);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.rend(), ref)[index_from_rend]);
+
+    ASSERT_EQ(MakeTransformIterator(input.begin(), ref) + i,
+              MakeTransformIterator(input.begin() + i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.rbegin(), ref) + i,
+              MakeTransformIterator(input.rbegin() + i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.end(), ref) - i,
+              MakeTransformIterator(input.end() - i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.rend(), ref) - i,
+              MakeTransformIterator(input.rend() - i, ref));
+  }
+  ASSERT_EQ(input.end(),
+            (MakeTransformIterator(input.begin(), ref) + input.size()).base());
+  ASSERT_EQ(MakeTransformIterator(input.end(), ref) - MakeTransformIterator(input.begin(), ref),
+            static_cast<ptrdiff_t>(input.size()));
+
+  // Test writing through the transform iterator.
+  std::list<int> transform_input({ 1, -1, 2, -2, 3, -3 });
+  std::vector<ValueHolder> transformed(transform_input.size(), 0);
+  std::transform(transform_input.begin(),
+                 transform_input.end(),
+                 MakeTransformIterator(transformed.begin(), ref),
+                 [](int v) { return -2 * v; });
+  ASSERT_EQ(std::vector<ValueHolder>({ -2, 2, -4, 4, -6, 6 }), transformed);
+}
+
+TEST(TransformIterator, VectorConstAndNonConstReference) {
+  struct Ref {
+    int& operator()(ValueHolder& h) const { return h.value; }
+    const int& operator()(const ValueHolder& h) const { return h.value; }
+  };
+  Ref ref;
+  std::vector<ValueHolder> input({ 7, 3, 1, 2, 4, 8 });
+  std::vector<int> output;
+
+  using vector_titer = decltype(MakeTransformIterator(input.begin(), ref));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_titer::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_titer::value_type>::value, "value_type");
+  static_assert(std::is_same<int*, vector_titer::pointer>::value, "pointer");
+  static_assert(std::is_same<int&, vector_titer::reference>::value, "reference");
+
+  using vector_ctiter = decltype(MakeTransformIterator(input.cbegin(), ref));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_ctiter::iterator_category>::value, "category");
+  // static_assert(std::is_same<int, vector_ctiter::value_type>::value, "value_type");
+  static_assert(std::is_same<const int*, vector_ctiter::pointer>::value, "pointer");
+  static_assert(std::is_same<const int&, vector_ctiter::reference>::value, "reference");
+
+  using vector_rtiter = decltype(MakeTransformIterator(input.rbegin(), ref));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_rtiter::iterator_category>::value, "category");
+  static_assert(std::is_same<int, vector_rtiter::value_type>::value, "value_type");
+  static_assert(std::is_same<int*, vector_rtiter::pointer>::value, "pointer");
+  static_assert(std::is_same<int&, vector_rtiter::reference>::value, "reference");
+
+  using vector_crtiter = decltype(MakeTransformIterator(input.crbegin(), ref));
+  static_assert(std::is_same<std::random_access_iterator_tag,
+                             vector_crtiter::iterator_category>::value, "category");
+  // static_assert(std::is_same<int, vector_crtiter::value_type>::value, "value_type");
+  static_assert(std::is_same<const int*, vector_crtiter::pointer>::value, "pointer");
+  static_assert(std::is_same<const int&, vector_crtiter::reference>::value, "reference");
+
+  std::copy(MakeTransformIterator(input.begin(), ref),
+            MakeTransformIterator(input.end(), ref),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 7, 3, 1, 2, 4, 8 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.cbegin(), ref),
+            MakeTransformIterator(input.cend(), ref),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 7, 3, 1, 2, 4, 8 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.rbegin(), ref),
+            MakeTransformIterator(input.rend(), ref),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 8, 4, 2, 1, 3, 7 }), output);
+  output.clear();
+
+  std::copy(MakeTransformIterator(input.crbegin(), ref),
+            MakeTransformIterator(input.crend(), ref),
+            std::back_inserter(output));
+  ASSERT_EQ(std::vector<int>({ 8, 4, 2, 1, 3, 7 }), output);
+  output.clear();
+
+  for (size_t i = 0; i != input.size(); ++i) {
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.begin(), ref)[i]);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.cbegin(), ref)[i]);
+    ptrdiff_t index_from_rbegin = static_cast<ptrdiff_t>(input.size() - i - 1u);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.rbegin(), ref)[index_from_rbegin]);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.crbegin(), ref)[index_from_rbegin]);
+    ptrdiff_t index_from_end = -static_cast<ptrdiff_t>(input.size() - i);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.end(), ref)[index_from_end]);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.cend(), ref)[index_from_end]);
+    ptrdiff_t index_from_rend = -1 - static_cast<ptrdiff_t>(i);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.rend(), ref)[index_from_rend]);
+    ASSERT_EQ(input[i].value, MakeTransformIterator(input.crend(), ref)[index_from_rend]);
+
+    ASSERT_EQ(MakeTransformIterator(input.begin(), ref) + i,
+              MakeTransformIterator(input.begin() + i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.cbegin(), ref) + i,
+              MakeTransformIterator(input.cbegin() + i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.rbegin(), ref) + i,
+              MakeTransformIterator(input.rbegin() + i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.crbegin(), ref) + i,
+              MakeTransformIterator(input.crbegin() + i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.end(), ref) - i,
+              MakeTransformIterator(input.end() - i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.cend(), ref) - i,
+              MakeTransformIterator(input.cend() - i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.rend(), ref) - i,
+              MakeTransformIterator(input.rend() - i, ref));
+    ASSERT_EQ(MakeTransformIterator(input.crend(), ref) - i,
+              MakeTransformIterator(input.crend() - i, ref));
+  }
+  ASSERT_EQ(input.end(),
+            (MakeTransformIterator(input.begin(), ref) + input.size()).base());
+  ASSERT_EQ(MakeTransformIterator(input.end(), ref) - MakeTransformIterator(input.begin(), ref),
+            static_cast<ptrdiff_t>(input.size()));
+
+  // Test iterator->const_iterator conversion and comparison.
+  auto it = MakeTransformIterator(input.begin(), ref);
+  decltype(MakeTransformIterator(input.cbegin(), ref)) cit = it;
+  static_assert(!std::is_same<decltype(it), decltype(cit)>::value, "Types must be different");
+  ASSERT_EQ(it, cit);
+  auto rit = MakeTransformIterator(input.rbegin(), ref);
+  decltype(MakeTransformIterator(input.crbegin(), ref)) crit(rit);
+  static_assert(!std::is_same<decltype(rit), decltype(crit)>::value, "Types must be different");
+  ASSERT_EQ(rit, crit);
+
+  // Test writing through the transform iterator.
+  std::list<int> transform_input({ 42, 73, 11, 17 });
+  std::vector<ValueHolder> transformed(transform_input.size(), 0);
+  std::transform(transform_input.begin(),
+                 transform_input.end(),
+                 MakeTransformIterator(transformed.begin(), ref),
+                 [](int v) { return -v; });
+  ASSERT_EQ(std::vector<ValueHolder>({ -42, -73, -11, -17 }), transformed);
+}
+
+TEST(TransformIterator, TransformRange) {
+  auto ref = [](ValueHolder& h) -> int& { return h.value; };  // NOLINT [readability/braces]
+  std::vector<ValueHolder> data({ 1, 0, 1, 3, 1, 0 });
+
+  for (int& v : MakeTransformRange(data, ref)) {
+    v += 11;
+  }
+  ASSERT_EQ(std::vector<ValueHolder>({ 12, 11, 12, 14, 12, 11 }), data);
+}
+
+}  // namespace art