[PATCH] D28371: Add missing operators for iterator_facade_base

[Zachary Turner via Phabricator via llvm-commits]

zturner created this revision.
zturner added a reviewer: chandlerc.
zturner added a subscriber: llvm-commits.

We were missing operators required to allow calling `std::distance`, as well as an `operator<` to match the existing `operator>`.


https://reviews.llvm.org/D28371

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


Index: llvm/include/llvm/ADT/iterator.h
===================================================================
--- llvm/include/llvm/ADT/iterator.h
+++ llvm/include/llvm/ADT/iterator.h
@@ -86,6 +86,12 @@
     tmp -= n;
     return tmp;
   }
+  DifferenceTypeT operator-(const DerivedT &i) const {
+    static_assert(
+        IsRandomAccess,
+        "The '-' operator is only defined for random access iterators.");
+    return i - *static_cast<const DerivedT *>(this);
+  }
 
   DerivedT &operator++() {
     return static_cast<DerivedT *>(this)->operator+=(1);
@@ -114,6 +120,13 @@
     return !static_cast<const DerivedT *>(this)->operator==(RHS);
   }
 
+  bool operator<(const DerivedT &RHS) const {
+    static_assert(
+        IsRandomAccess,
+        "Relational operators are only defined for random access iterators.");
+    return !static_cast<const DerivedT *>(this)->operator>(RHS) &&
+           !static_cast<const DerivedT *>(this)->operator==(RHS);
+  }
   bool operator>(const DerivedT &RHS) const {
     static_assert(
         IsRandomAccess,


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D28371.83276.patch
Type: text/x-patch
Size: 1060 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20170105/ebf8da87/attachment.bin>