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//===- iterator_range.h - A range adaptor for iterators ---------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
/// \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.
#include <iterator>
#include <utility>
namespace llvm {
/// 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;
//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; }
/// 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(adl_begin(std::declval<T>()))> drop_begin(T &&t,
int n) {
return make_range(std::next(adl_begin(t), n), adl_end(t));