Cut macro FOR_EACH_RANGE_R

Summary: [Folly] Cut macro `FOR_EACH_RANGE_R`.

Reviewed By: aary, danobi

Differential Revision: D14058731

fbshipit-source-id: d31c0673785d467665598e2138b6b6082d9629ab

folly/container/Foreach.h

@@ -279,28 +279,6 @@ notThereYet(T& iter, const U& end) {
 
 #endif
 
-/**
- * downTo is similar to notThereYet, but in reverse - it helps the
- * FOR_EACH_RANGE_R macro.
- */
-template <class T, class U>
-typename std::enable_if<HasLess<U, T>::value, bool>::type downTo(
-    T& iter,
-    const U& begin) {
-  return begin < iter--;
-}
-
-template <class T, class U>
-typename std::enable_if<!HasLess<U, T>::value, bool>::type downTo(
-    T& iter,
-    const U& begin) {
-  if (iter == begin) {
-    return false;
-  }
-  --iter;
-  return true;
-}
-
 } // namespace detail
 } // namespace folly
 
@@ -315,13 +293,4 @@ typename std::enable_if<!HasLess<U, T>::value, bool>::type downTo(
        ::folly::detail::notThereYet(i, (end)); \
        ++i)
 
-/*
- * Look at the Ranges-v3 views and you'll probably find an easier way to build
- * the view you want but the equivalent is roughly:
- *
- *    for (auto& element : make_subrange(begin, end) | view::reverse)
- */
-#define FOR_EACH_RANGE_R(i, begin, end) \
-  for (auto i = (false ? (begin) : (end)); ::folly::detail::downTo(i, (begin));)
-
 #include <folly/container/Foreach-inl.h>

folly/container/test/ForeachBenchmark.cpp

@@ -342,12 +342,6 @@ BENCHMARK(ForEachDescendingManual, iters) {
   doNotOptimizeAway(sum);
 }
 
-BENCHMARK(ForEachRangeR, iters) {
-  int sum = 1;
-  FOR_EACH_RANGE_R (i, 1U, iters) { sum *= i; }
-  doNotOptimizeAway(sum);
-}
-
 BENCHMARK(CharVecForRange, iters) {
   BENCHMARK_SUSPEND {
     setupCharVecBenchmark(iters);

folly/container/test/ForeachTest.cpp

@@ -443,21 +443,3 @@ TEST(Foreach, ForEachEnumerateBreak) {
   EXPECT_EQ(sumIter, 3); // 1 + 2
   EXPECT_EQ(numIterations, 2);
 }
-
-TEST(Foreach, ForEachRangeR) {
-  int sum = 0;
-
-  FOR_EACH_RANGE_R (i, 0, 0) { sum += i; }
-  EXPECT_EQ(0, sum);
-
-  FOR_EACH_RANGE_R (i, 0, -1) { sum += i; }
-  EXPECT_EQ(0, sum);
-
-  FOR_EACH_RANGE_R (i, 0, 5) { sum += i; }
-  EXPECT_EQ(10, sum);
-
-  std::list<int> lst = {0, 1, 2, 3, 4};
-  sum = 0;
-  FOR_EACH_RANGE_R (i, lst.begin(), lst.end()) { sum += *i; }
-  EXPECT_EQ(10, sum);
-}