Prepare wpiutil for merge into allwpilib.

wpiutil/src/main/native/include/llvm/iterator_range.h

@@ -0,0 +1,68 @@
+//===- iterator_range.h - A range adaptor for iterators ---------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This provides a very simple, boring adaptor for a begin and end iterator
+/// into a range type. This should be used to build range views that work well
+/// with range based for loops and range based constructors.
+///
+/// Note that code here follows more standards-based coding conventions as it
+/// is mirroring proposed interfaces for standardization.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_ITERATOR_RANGE_H
+#define LLVM_ADT_ITERATOR_RANGE_H
+
+#include <utility>
+#include <iterator>
+
+namespace llvm {
+
+/// \brief A range adaptor for a pair of iterators.
+///
+/// This just wraps two iterators into a range-compatible interface. Nothing
+/// fancy at all.
+template <typename IteratorT>
+class iterator_range {
+  IteratorT begin_iterator, end_iterator;
+
+public:
+  //TODO: Add SFINAE to test that the Container's iterators match the range's
+  //      iterators.
+  template <typename Container>
+  iterator_range(Container &&c)
+  //TODO: Consider ADL/non-member begin/end calls.
+      : begin_iterator(c.begin()), end_iterator(c.end()) {}
+  iterator_range(IteratorT begin_iterator, IteratorT end_iterator)
+      : begin_iterator(std::move(begin_iterator)),
+        end_iterator(std::move(end_iterator)) {}
+
+  IteratorT begin() const { return begin_iterator; }
+  IteratorT end() const { return end_iterator; }
+};
+
+/// \brief Convenience function for iterating over sub-ranges.
+///
+/// This provides a bit of syntactic sugar to make using sub-ranges
+/// in for loops a bit easier. Analogous to std::make_pair().
+template <class T> iterator_range<T> make_range(T x, T y) {
+  return iterator_range<T>(std::move(x), std::move(y));
+}
+
+template <typename T> iterator_range<T> make_range(std::pair<T, T> p) {
+  return iterator_range<T>(std::move(p.first), std::move(p.second));
+}
+
+template<typename T>
+iterator_range<decltype(begin(std::declval<T>()))> drop_begin(T &&t, int n) {
+  return make_range(std::next(begin(t), n), end(t));
+}
+}
+
+#endif