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      1 //===--- AttrIterator.h - Classes for attribute iteration -------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 //  This file defines the Attr vector and specific_attr_iterator interfaces.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #ifndef LLVM_CLANG_AST_ATTRITERATOR_H
     15 #define LLVM_CLANG_AST_ATTRITERATOR_H
     16 
     17 #include "clang/Basic/LLVM.h"
     18 #include <iterator>
     19 
     20 namespace clang {
     21   class ASTContext;
     22   class Attr;
     23 }
     24 
     25 // Defined in ASTContext.h
     26 void *operator new(size_t Bytes, const clang::ASTContext &C,
     27                    size_t Alignment = 8);
     28 // FIXME: Being forced to not have a default argument here due to redeclaration
     29 //        rules on default arguments sucks
     30 void *operator new[](size_t Bytes, const clang::ASTContext &C,
     31                      size_t Alignment);
     32 
     33 // It is good practice to pair new/delete operators.  Also, MSVC gives many
     34 // warnings if a matching delete overload is not declared, even though the
     35 // throw() spec guarantees it will not be implicitly called.
     36 void operator delete(void *Ptr, const clang::ASTContext &C, size_t);
     37 void operator delete[](void *Ptr, const clang::ASTContext &C, size_t);
     38 
     39 namespace clang {
     40 
     41 /// AttrVec - A vector of Attr, which is how they are stored on the AST.
     42 typedef SmallVector<Attr*, 2> AttrVec;
     43 typedef SmallVector<const Attr*, 2> ConstAttrVec;
     44 
     45 /// specific_attr_iterator - Iterates over a subrange of an AttrVec, only
     46 /// providing attributes that are of a specific type.
     47 template <typename SpecificAttr, typename Container = AttrVec>
     48 class specific_attr_iterator {
     49   typedef typename Container::const_iterator Iterator;
     50 
     51   /// Current - The current, underlying iterator.
     52   /// In order to ensure we don't dereference an invalid iterator unless
     53   /// specifically requested, we don't necessarily advance this all the
     54   /// way. Instead, we advance it when an operation is requested; if the
     55   /// operation is acting on what should be a past-the-end iterator,
     56   /// then we offer no guarantees, but this way we do not dereference a
     57   /// past-the-end iterator when we move to a past-the-end position.
     58   mutable Iterator Current;
     59 
     60   void AdvanceToNext() const {
     61     while (!isa<SpecificAttr>(*Current))
     62       ++Current;
     63   }
     64 
     65   void AdvanceToNext(Iterator I) const {
     66     while (Current != I && !isa<SpecificAttr>(*Current))
     67       ++Current;
     68   }
     69 
     70 public:
     71   typedef SpecificAttr*             value_type;
     72   typedef SpecificAttr*             reference;
     73   typedef SpecificAttr*             pointer;
     74   typedef std::forward_iterator_tag iterator_category;
     75   typedef std::ptrdiff_t            difference_type;
     76 
     77   specific_attr_iterator() : Current() { }
     78   explicit specific_attr_iterator(Iterator i) : Current(i) { }
     79 
     80   reference operator*() const {
     81     AdvanceToNext();
     82     return cast<SpecificAttr>(*Current);
     83   }
     84   pointer operator->() const {
     85     AdvanceToNext();
     86     return cast<SpecificAttr>(*Current);
     87   }
     88 
     89   specific_attr_iterator& operator++() {
     90     ++Current;
     91     return *this;
     92   }
     93   specific_attr_iterator operator++(int) {
     94     specific_attr_iterator Tmp(*this);
     95     ++(*this);
     96     return Tmp;
     97   }
     98 
     99   friend bool operator==(specific_attr_iterator Left,
    100                          specific_attr_iterator Right) {
    101     assert((Left.Current == nullptr) == (Right.Current == nullptr));
    102     if (Left.Current < Right.Current)
    103       Left.AdvanceToNext(Right.Current);
    104     else
    105       Right.AdvanceToNext(Left.Current);
    106     return Left.Current == Right.Current;
    107   }
    108   friend bool operator!=(specific_attr_iterator Left,
    109                          specific_attr_iterator Right) {
    110     return !(Left == Right);
    111   }
    112 };
    113 
    114 template <typename SpecificAttr, typename Container>
    115 inline specific_attr_iterator<SpecificAttr, Container>
    116           specific_attr_begin(const Container& container) {
    117   return specific_attr_iterator<SpecificAttr, Container>(container.begin());
    118 }
    119 template <typename SpecificAttr, typename Container>
    120 inline specific_attr_iterator<SpecificAttr, Container>
    121           specific_attr_end(const Container& container) {
    122   return specific_attr_iterator<SpecificAttr, Container>(container.end());
    123 }
    124 
    125 template <typename SpecificAttr, typename Container>
    126 inline bool hasSpecificAttr(const Container& container) {
    127   return specific_attr_begin<SpecificAttr>(container) !=
    128           specific_attr_end<SpecificAttr>(container);
    129 }
    130 template <typename SpecificAttr, typename Container>
    131 inline SpecificAttr *getSpecificAttr(const Container& container) {
    132   specific_attr_iterator<SpecificAttr, Container> i =
    133       specific_attr_begin<SpecificAttr>(container);
    134   if (i != specific_attr_end<SpecificAttr>(container))
    135     return *i;
    136   else
    137     return nullptr;
    138 }
    139 
    140 }  // end namespace clang
    141 
    142 #endif
    143