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 "llvm/ADT/ADL.h"
22#include <type_traits>
23#include <utility>
24
25namespace llvm {
26
27template <typename From, typename To, typename = void>
28struct explicitly_convertible : std::false_type {};
29
30template <typename From, typename To>
31struct explicitly_convertible<
32 From, To,
33 std::void_t<decltype(static_cast<To>(
34 std::declval<std::add_rvalue_reference_t<From>>()))>> : std::true_type {
35};
36
37/// A range adaptor for a pair of iterators.
38///
39/// This just wraps two iterators into a range-compatible interface. Nothing
40/// fancy at all.
41template <typename IteratorT>
42class iterator_range {
43 IteratorT begin_iterator, end_iterator;
44
45public:
46#if __GNUC__ == 7 || (__GNUC__ == 8 && __GNUC_MINOR__ < 4)
47 // Be careful no to break gcc-7 and gcc-8 < 8.4 on the mlir target.
48 // See https://github.com/llvm/llvm-project/issues/63843
49 template <typename Container>
50#else
51 template <
52 typename Container,
53 std::enable_if_t<explicitly_convertible<
54 llvm::detail::IterOfRange<Container>, IteratorT>::value> * = nullptr>
55#endif
56 iterator_range(Container &&c)
57 : begin_iterator(adl_begin(c)), end_iterator(adl_end(c)) {
58 }
59 iterator_range(IteratorT begin_iterator, IteratorT end_iterator)
60 : begin_iterator(std::move(begin_iterator)),
61 end_iterator(std::move(end_iterator)) {}
62
63 IteratorT begin() const { return begin_iterator; }
64 IteratorT end() const { return end_iterator; }
65 bool empty() const { return begin_iterator == end_iterator; }
66};
67
68template <typename Container>
69iterator_range(Container &&)
70 -> iterator_range<llvm::detail::IterOfRange<Container>>;
71
72/// Convenience function for iterating over sub-ranges.
73///
74/// This provides a bit of syntactic sugar to make using sub-ranges
75/// in for loops a bit easier. Analogous to std::make_pair().
76template <class T> iterator_range<T> make_range(T x, T y) {
77 return iterator_range<T>(std::move(x), std::move(y));
78}
79
80template <typename T> iterator_range<T> make_range(std::pair<T, T> p) {
81 return iterator_range<T>(std::move(p.first), std::move(p.second));
82}
83
84}
85
86#endif
87

source code of llvm/include/llvm/ADT/iterator_range.h