mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 20:00:12 +01:00
Richard SmithandJon Ross-Perkins
dc7839e893
Use it to replace most existing modernize-loop-convert lints with range-based for loops. As requested in review of #5475. --------- Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
69 lines
2.3 KiB
C++
69 lines
2.3 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
|
|
// Exceptions. See /LICENSE for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
|
|
#ifndef CARBON_COMMON_GROWING_RANGE_H_
|
|
#define CARBON_COMMON_GROWING_RANGE_H_
|
|
|
|
#include <ranges>
|
|
|
|
namespace Carbon {
|
|
|
|
// A range adaptor for a random-access container such as `std::vector` or
|
|
// `llvm::SmallVector` that might have elements appended during the iteration.
|
|
// This adaptor avoids invalidation issues by tracking an index instead of an
|
|
// iterator, and by returning by value from `operator*` instead of by reference.
|
|
//
|
|
// This class is intended only for use as the range in a range-based for loop,
|
|
// and as such does not provide a complete range or iterator interface. Instead,
|
|
// it provides only the interface required by the range-based for loop.
|
|
template <typename ContainerT>
|
|
requires std::ranges::sized_range<ContainerT> &&
|
|
std::ranges::random_access_range<ContainerT>
|
|
class GrowingRange {
|
|
public:
|
|
// An end sentinel for the range.
|
|
class End {};
|
|
|
|
// An iterator into a potentially-growing range. Tracks the container and the
|
|
// current index, and indexes the container on each dereference.
|
|
class Iterator {
|
|
public:
|
|
// Dereferences the iterator. These intentionally don't return by reference,
|
|
// to avoid handing out a reference that would be invalidated when the
|
|
// container grows during the traversal.
|
|
auto operator*() -> auto { return (*container_)[index_]; }
|
|
auto operator*() const -> auto { return (*container_)[index_]; }
|
|
|
|
friend auto operator!=(Iterator it, End /*end*/) -> bool {
|
|
return it.index_ != it.container_->size();
|
|
}
|
|
|
|
auto operator++() -> void { ++index_; }
|
|
|
|
private:
|
|
friend class GrowingRange;
|
|
|
|
explicit Iterator(const ContainerT* container)
|
|
: container_(container), index_(0) {}
|
|
|
|
const ContainerT* container_;
|
|
size_t index_;
|
|
};
|
|
|
|
explicit GrowingRange(const ContainerT& container) : container_(&container) {}
|
|
|
|
auto begin() const -> Iterator { return Iterator(container_); }
|
|
auto end() const -> End { return {}; }
|
|
|
|
private:
|
|
const ContainerT* container_;
|
|
};
|
|
|
|
template <typename ContainerT>
|
|
GrowingRange(const ContainerT&) -> GrowingRange<ContainerT>;
|
|
|
|
} // namespace Carbon
|
|
|
|
#endif // CARBON_COMMON_GROWING_RANGE_H_
|