AttrIterator.h

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//===- AttrIterator.h - Classes for attribute iteration ---------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
//  This file defines the Attr vector and specific_attr_iterator interfaces.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_CLANG_AST_ATTRITERATOR_H
#define LLVM_CLANG_AST_ATTRITERATOR_H
 
#include "clang/Basic/LLVM.h"
#include "llvm/ADT/ADL.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/Casting.h"
#include <cassert>
#include <cstddef>
#include <iterator>
#include <type_traits>
 
namespace clang {
 
class Attr;
 
/// AttrVec - A vector of Attr, which is how they are stored on the AST.
using AttrVec = SmallVector<Attr *, 4>;
 
/// specific_attr_iterator - Iterates over a subrange of an AttrVec, only
/// providing attributes that are of a specific type.
template <typename SpecificAttr, typename Container = AttrVec>
class specific_attr_iterator {
  using Iterator = typename Container::const_iterator;
 
  /// Current - The current, underlying iterator.
  /// In order to ensure we don't dereference an invalid iterator unless
  /// specifically requested, we don't necessarily advance this all the
  /// way. Instead, we advance it when an operation is requested; if the
  /// operation is acting on what should be a past-the-end iterator,
  /// then we offer no guarantees, but this way we do not dereference a
  /// past-the-end iterator when we move to a past-the-end position.
  mutable Iterator Current;
 
  void AdvanceToNext() const {
    while (!isa<SpecificAttr>(*Current))
      ++Current;
  }
 
  void AdvanceToNext(Iterator I) const {
    while (Current != I && !isa<SpecificAttr>(*Current))
      ++Current;
  }
 
public:
  using value_type = SpecificAttr *;
  using reference = SpecificAttr *;
  using pointer = SpecificAttr *;
  using iterator_category = std::forward_iterator_tag;
  using difference_type = std::ptrdiff_t;
 
  specific_attr_iterator() = default;
  explicit specific_attr_iterator(Iterator i) : Current(i) {}
 
  reference operator*() const {
    AdvanceToNext();