[base] Add iterator_range helper class.

test/unittests/base/iterator-unittest.cc

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/base/iterator.h"
+
+#include <deque>
+
+#include "test/unittests/test-utils.h"
+
+namespace v8 {
+namespace base {
+
+TEST(IteratorTest, IteratorRangeEmpty) {
+  base::iterator_range<char*> r;
+  EXPECT_EQ(r.begin(), r.end());
+  EXPECT_EQ(r.end(), r.cend());
+  EXPECT_EQ(r.begin(), r.cbegin());
+  EXPECT_TRUE(r.empty());
+  EXPECT_EQ(0, r.size());
+}
+
+
+TEST(IteratorTest, IteratorRangeArray) {
+  int array[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+  base::iterator_range<int*> r1(&array[0], &array[10]);
+  for (auto i : r1) {
+    EXPECT_EQ(array[i], i);
+  }
+  EXPECT_EQ(10, r1.size());
+  EXPECT_FALSE(r1.empty());
+  for (size_t i = 0; i < arraysize(array); ++i) {
+    EXPECT_EQ(r1[i], array[i]);
+  }
+  base::iterator_range<int*> r2(&array[0], &array[0]);
+  EXPECT_EQ(0, r2.size());
+  EXPECT_TRUE(r2.empty());
+  for (auto i : array) {
+    EXPECT_EQ(r2.end(), std::find(r2.begin(), r2.end(), i));
+  }
+}
+
+
+TEST(IteratorTest, IteratorRangeDeque) {
+  typedef std::deque<unsigned> C;
+  C c;
+  c.push_back(1);
+  c.push_back(2);
+  c.push_back(2);
+  base::iterator_range<typename C::iterator> r(c.begin(), c.end());
+  EXPECT_EQ(3, r.size());
+  EXPECT_FALSE(r.empty());
+  EXPECT_TRUE(c.begin() == r.begin());
+  EXPECT_TRUE(c.end() == r.end());
+  EXPECT_EQ(0, std::count(r.begin(), r.end(), 0));
+  EXPECT_EQ(1, std::count(r.begin(), r.end(), 1));
+  EXPECT_EQ(2, std::count(r.begin(), r.end(), 2));
+}
+
+}  // namespace base
+}  // namespace v8