[PATCH] D63632: Update the llvm::enumerate utility class result_pair to use the 'iterator_traits<R>::reference' instead of 'ValueOfIter<R> &'.

[River Riddle via Phabricator via llvm-commits]

rriddle created this revision.
rriddle added reviewers: jpienaar, mehdi_amini.
Herald added subscribers: llvm-commits, kristina, dexonsmith.
Herald added a project: LLVM.

Update the llvm::enumerate helper class result_pair<R> to use the 'iterator_traits<R>::reference' type as the result of 'value()' instead 'ValueOfRange<R> &'. This enables support for iterators that return value types, i.e. non reference. This is a common pattern for some classes of iterators, e.g. mapped_iterator.


Repository:
  rL LLVM

https://reviews.llvm.org/D63632

Files:
  llvm/include/llvm/ADT/STLExtras.h


Index: llvm/include/llvm/ADT/STLExtras.h
===================================================================
--- llvm/include/llvm/ADT/STLExtras.h
+++ llvm/include/llvm/ADT/STLExtras.h
@@ -1506,6 +1506,10 @@
 template <typename R> class enumerator_iter;
 
 template <typename R> struct result_pair {
+  using value_reference =
+      typename std::iterator_traits<IterOfRange<R>>::reference;
+
+public:
   friend class enumerator_iter<R>;
 
   result_pair() = default;
@@ -1519,8 +1523,8 @@
   }
 
   std::size_t index() const { return Index; }
-  const ValueOfRange<R> &value() const { return *Iter; }
-  ValueOfRange<R> &value() { return *Iter; }
+  const value_reference value() const { return *Iter; }
+  value_reference value() { return *Iter; }
 
 private:
   std::size_t Index = std::numeric_limits<std::size_t>::max();


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