1//===- iterator_range.h - A range adaptor for iterators ---------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9/// \file
10/// This provides a very simple, boring adaptor for a begin and end iterator
11/// into a range type. This should be used to build range views that work well
12/// with range based for loops and range based constructors.
13///
14/// Note that code here follows more standards-based coding conventions as it
15/// is mirroring proposed interfaces for standardization.
16///
17//===----------------------------------------------------------------------===//
18
19#ifndef LLVM_ADT_ITERATOR_RANGE_H
20#define LLVM_ADT_ITERATOR_RANGE_H
21
22#include <utility>
23#include <iterator>
24
25namespace llvm {
26
27/// \brief A range adaptor for a pair of iterators.
28///
29/// This just wraps two iterators into a range-compatible interface. Nothing
30/// fancy at all.
31template <typename IteratorT>
32class iterator_range {
33  IteratorT begin_iterator, end_iterator;
34
35public:
36  //TODO: Add SFINAE to test that the Container's iterators match the range's
37  //      iterators.
38  template <typename Container>
39  iterator_range(Container &&c)
40  //TODO: Consider ADL/non-member begin/end calls.
41      : begin_iterator(c.begin()), end_iterator(c.end()) {}
42  iterator_range(IteratorT begin_iterator, IteratorT end_iterator)
43      : begin_iterator(std::move(begin_iterator)),
44        end_iterator(std::move(end_iterator)) {}
45
46  IteratorT begin() const { return begin_iterator; }
47  IteratorT end() const { return end_iterator; }
48};
49
50/// \brief Convenience function for iterating over sub-ranges.
51///
52/// This provides a bit of syntactic sugar to make using sub-ranges
53/// in for loops a bit easier. Analogous to std::make_pair().
54template <class T> iterator_range<T> make_range(T x, T y) {
55  return iterator_range<T>(std::move(x), std::move(y));
56}
57
58template <typename T> iterator_range<T> make_range(std::pair<T, T> p) {
59  return iterator_range<T>(std::move(p.first), std::move(p.second));
60}
61
62template<typename T>
63iterator_range<decltype(begin(std::declval<T>()))> drop_begin(T &&t, int n) {
64  return make_range(std::next(begin(t), n), end(t));
65}
66}
67
68#endif
69