1//===- iterator_range.h - A range adaptor for iterators ---------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8/// \file
9/// This provides a very simple, boring adaptor for a begin and end iterator
10/// into a range type. This should be used to build range views that work well
11/// with range based for loops and range based constructors.
12///
13/// Note that code here follows more standards-based coding conventions as it
14/// is mirroring proposed interfaces for standardization.
15///
16//===----------------------------------------------------------------------===//
17
18#ifndef LLVM_ADT_ITERATOR_RANGE_H
19#define LLVM_ADT_ITERATOR_RANGE_H
20
21#include <iterator>
22#include <utility>
23
24namespace llvm {
25
26/// A range adaptor for a pair of iterators.
27///
28/// This just wraps two iterators into a range-compatible interface. Nothing
29/// fancy at all.
30template <typename IteratorT>
31class iterator_range {
32 IteratorT begin_iterator, end_iterator;
33
34public:
35 //TODO: Add SFINAE to test that the Container's iterators match the range's
36 // iterators.
37 template <typename Container>
38 iterator_range(Container &&c)
39 //TODO: Consider ADL/non-member begin/end calls.
40 : begin_iterator(c.begin()), end_iterator(c.end()) {}
41 iterator_range(IteratorT begin_iterator, IteratorT end_iterator)
42 : begin_iterator(std::move(begin_iterator)),
43 end_iterator(std::move(end_iterator)) {}
44
45 IteratorT begin() const { return begin_iterator; }
46 IteratorT end() const { return end_iterator; }
47};
48
49/// Convenience function for iterating over sub-ranges.
50///
51/// This provides a bit of syntactic sugar to make using sub-ranges
52/// in for loops a bit easier. Analogous to std::make_pair().
53template <class T> iterator_range<T> make_range(T x, T y) {
54 return iterator_range<T>(std::move(x), std::move(y));
55}
56
57template <typename T> iterator_range<T> make_range(std::pair<T, T> p) {
58 return iterator_range<T>(std::move(p.first), std::move(p.second));
59}
60
61template <typename T>
62iterator_range<decltype(adl_begin(std::declval<T>()))> drop_begin(T &&t,
63 int n) {
64 return make_range(std::next(adl_begin(t), n), adl_end(t));
65}
66}
67
68#endif
69