1 //===- AttrIterator.h - Classes for attribute iteration ---------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 //  This file defines the Attr vector and specific_attr_iterator interfaces.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_CLANG_AST_ATTRITERATOR_H
14 #define LLVM_CLANG_AST_ATTRITERATOR_H
15 
16 #include "clang/Basic/LLVM.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/Support/Casting.h"
19 #include <cassert>
20 #include <cstddef>
21 #include <iterator>
22 
23 namespace clang {
24 
25 class Attr;
26 
27 /// AttrVec - A vector of Attr, which is how they are stored on the AST.
28 using AttrVec = SmallVector<Attr *, 4>;
29 
30 /// specific_attr_iterator - Iterates over a subrange of an AttrVec, only
31 /// providing attributes that are of a specific type.
32 template <typename SpecificAttr, typename Container = AttrVec>
33 class specific_attr_iterator {
34   using Iterator = typename Container::const_iterator;
35 
36   /// Current - The current, underlying iterator.
37   /// In order to ensure we don't dereference an invalid iterator unless
38   /// specifically requested, we don't necessarily advance this all the
39   /// way. Instead, we advance it when an operation is requested; if the
40   /// operation is acting on what should be a past-the-end iterator,
41   /// then we offer no guarantees, but this way we do not dereference a
42   /// past-the-end iterator when we move to a past-the-end position.
43   mutable Iterator Current;
44 
45   void AdvanceToNext() const {
46     while (!isa<SpecificAttr>(*Current))
47       ++Current;
48   }
49 
50   void AdvanceToNext(Iterator I) const {
51     while (Current != I && !isa<SpecificAttr>(*Current))
52       ++Current;
53   }
54 
55 public:
56   using value_type = SpecificAttr *;
57   using reference = SpecificAttr *;
58   using pointer = SpecificAttr *;
59   using iterator_category = std::forward_iterator_tag;
60   using difference_type = std::ptrdiff_t;
61 
62   specific_attr_iterator() = default;
63   explicit specific_attr_iterator(Iterator i) : Current(i) {}
64 
65   reference operator*() const {
66     AdvanceToNext();
67     return cast<SpecificAttr>(*Current);
68   }
69   pointer operator->() const {
70     AdvanceToNext();
71     return cast<SpecificAttr>(*Current);
72   }
73 
74   specific_attr_iterator& operator++() {
75     ++Current;
76     return *this;
77   }
78   specific_attr_iterator operator++(int) {
79     specific_attr_iterator Tmp(*this);
80     ++(*this);
81     return Tmp;
82   }
83 
84   friend bool operator==(specific_attr_iterator Left,
85                          specific_attr_iterator Right) {
86     assert((Left.Current == nullptr) == (Right.Current == nullptr));
87     if (Left.Current < Right.Current)
88       Left.AdvanceToNext(Right.Current);
89     else
90       Right.AdvanceToNext(Left.Current);
91     return Left.Current == Right.Current;
92   }
93   friend bool operator!=(specific_attr_iterator Left,
94                          specific_attr_iterator Right) {
95     return !(Left == Right);
96   }
97 };
98 
99 template <typename SpecificAttr, typename Container>
100 inline specific_attr_iterator<SpecificAttr, Container>
101           specific_attr_begin(const Container& container) {
102   return specific_attr_iterator<SpecificAttr, Container>(container.begin());
103 }
104 template <typename SpecificAttr, typename Container>
105 inline specific_attr_iterator<SpecificAttr, Container>
106           specific_attr_end(const Container& container) {
107   return specific_attr_iterator<SpecificAttr, Container>(container.end());
108 }
109 
110 template <typename SpecificAttr, typename Container>
111 inline bool hasSpecificAttr(const Container& container) {
112   return specific_attr_begin<SpecificAttr>(container) !=
113           specific_attr_end<SpecificAttr>(container);
114 }
115 template <typename SpecificAttr, typename Container>
116 inline SpecificAttr *getSpecificAttr(const Container& container) {
117   specific_attr_iterator<SpecificAttr, Container> i =
118       specific_attr_begin<SpecificAttr>(container);
119   if (i != specific_attr_end<SpecificAttr>(container))
120     return *i;
121   else
122     return nullptr;
123 }
124 
125 } // namespace clang
126 
127 #endif // LLVM_CLANG_AST_ATTRITERATOR_H
128