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 <iterator>
23 #include <utility>
24
25 namespace llvm {
26
27 /// 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.
31 template <typename IteratorT>
32 class iterator_range {
33 IteratorT begin_iterator, end_iterator;
34
35 public:
36 //TODO: Add SFINAE to test that the Container's iterators match the range's
37 // iterators.
38 template <typename Container>
iterator_range(Container && c)39 iterator_range(Container &&c)
40 //TODO: Consider ADL/non-member begin/end calls.
41 : begin_iterator(c.begin()), end_iterator(c.end()) {}
iterator_range(IteratorT begin_iterator,IteratorT end_iterator)42 iterator_range(IteratorT begin_iterator, IteratorT end_iterator)
43 : begin_iterator(std::move(begin_iterator)),
44 end_iterator(std::move(end_iterator)) {}
45
begin()46 IteratorT begin() const { return begin_iterator; }
end()47 IteratorT end() const { return end_iterator; }
48 };
49
50 /// 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().
make_range(T x,T y)54 template <class T> iterator_range<T> make_range(T x, T y) {
55 return iterator_range<T>(std::move(x), std::move(y));
56 }
57
make_range(std::pair<T,T> p)58 template <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
62 template <typename T>
drop_begin(T && t,int n)63 iterator_range<decltype(adl_begin(std::declval<T>()))> drop_begin(T &&t,
64 int n) {
65 return make_range(std::next(adl_begin(t), n), adl_end(t));
66 }
67 }
68
69 #endif
70