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