[PATCH] D74967: [NFC] Add filters to hasNItems and hasNItemsOrMore

[Tyker via Phabricator via llvm-commits]

Tyker created this revision.
Tyker added a reviewer: lebedev.ri.
Herald added subscribers: llvm-commits, dexonsmith.
Herald added a project: LLVM.

https://reviews.llvm.org/D74967

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
@@ -1510,33 +1510,45 @@
 
 /// Return true if the sequence [Begin, End) has exactly N items. Runs in O(N)
 /// time. Not meant for use with random-access iterators.
-template <typename IterTy>
+/// Can optionally take a predicate to filter lazily some items.
+template <typename IterTy,
+          typename Pred = bool (*)(const decltype(*std::declval<IterTy>()) &)>
 bool hasNItems(
     IterTy &&Begin, IterTy &&End, unsigned N,
+    Pred &&ShouldBeCounted =
+        [](const decltype(*std::declval<IterTy>()) &) { return true; },
     std::enable_if_t<
         !std::is_same<typename std::iterator_traits<std::remove_reference_t<
                           decltype(Begin)>>::iterator_category,
                       std::random_access_iterator_tag>::value,
         void> * = nullptr) {
-  for (; N; --N, ++Begin)
+  for (; N; ++Begin) {
     if (Begin == End)
       return false; // Too few.
+    N -= ShouldBeCounted(*Begin);
+  }
   return Begin == End;
 }
 
 /// Return true if the sequence [Begin, End) has N or more items. Runs in O(N)
 /// time. Not meant for use with random-access iterators.
-template <typename IterTy>
+/// Can optionally take a predicate to filter lazily some items.
+template <typename IterTy,
+          typename Pred = bool (*)(const decltype(*std::declval<IterTy>()) &)>
 bool hasNItemsOrMore(
     IterTy &&Begin, IterTy &&End, unsigned N,
+    Pred &&ShouldBeCounted =
+        [](const decltype(*std::declval<IterTy>()) &) { return true; },
     std::enable_if_t<
         !std::is_same<typename std::iterator_traits<std::remove_reference_t<
                           decltype(Begin)>>::iterator_category,
                       std::random_access_iterator_tag>::value,
         void> * = nullptr) {
-  for (; N; --N, ++Begin)
+  for (; N; ++Begin) {
     if (Begin == End)
       return false; // Too few.
+    N -= ShouldBeCounted(*Begin);
+  }
   return true;
 }
 


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