src/compiler-rt/lib/sanitizer_common/sanitizer_list.h

   1 //===-- sanitizer_list.h ----------------------------------------*- 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 contains implementation of a list class to be used by
  11 // ThreadSanitizer, etc run-times.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef SANITIZER_LIST_H
  16 #define SANITIZER_LIST_H
  17
  18 #include "sanitizer_internal_defs.h"
  19
  20 namespace __sanitizer {
  21
  22 // Intrusive singly-linked list with size(), push_back(), push_front()
  23 // pop_front(), append_front() and append_back().
  24 // This class should be a POD (so that it can be put into TLS)
  25 // and an object with all zero fields should represent a valid empty list.
  26 // This class does not have a CTOR, so clear() should be called on all
  27 // non-zero-initialized objects before using.
  28 template<class Item>
  29 struct IntrusiveList {
  30   friend class Iterator;
  31
  32   void clear() {
  33     first_ = last_ = nullptr;
  34     size_ = 0;
  35   }
  36
  37   bool empty() const { return size_ == 0; }
  38   uptr size() const { return size_; }
  39
  40   void push_back(Item *x) {
  41     if (empty()) {
  42       x->next = nullptr;
  43       first_ = last_ = x;
  44       size_ = 1;
  45     } else {
  46       x->next = nullptr;
  47       last_->next = x;
  48       last_ = x;
  49       size_++;
  50     }
  51   }
  52
  53   void push_front(Item *x) {
  54     if (empty()) {
  55       x->next = nullptr;
  56       first_ = last_ = x;
  57       size_ = 1;
  58     } else {
  59       x->next = first_;
  60       first_ = x;
  61       size_++;
  62     }
  63   }
  64
  65   void pop_front() {
  66     CHECK(!empty());
  67     first_ = first_->next;
  68     if (!first_)
  69       last_ = nullptr;
  70     size_--;
  71   }
  72
  73   Item *front() { return first_; }
  74   Item *back() { return last_; }
  75
  76   void append_front(IntrusiveList<Item> *l) {
  77     CHECK_NE(this, l);
  78     if (l->empty())
  79       return;
  80     if (empty()) {
  81       *this = *l;
  82     } else if (!l->empty()) {
  83       l->last_->next = first_;
  84       first_ = l->first_;
  85       size_ += l->size();
  86     }
  87     l->clear();
  88   }
  89
  90   void append_back(IntrusiveList<Item> *l) {
  91     CHECK_NE(this, l);
  92     if (l->empty())
  93       return;
  94     if (empty()) {
  95       *this = *l;
  96     } else {
  97       last_->next = l->first_;
  98       last_ = l->last_;
  99       size_ += l->size();
 100     }
 101     l->clear();
 102   }
 103
 104   void CheckConsistency() {
 105     if (size_ == 0) {
 106       CHECK_EQ(first_, 0);
 107       CHECK_EQ(last_, 0);
 108     } else {
 109       uptr count = 0;
 110       for (Item *i = first_; ; i = i->next) {
 111         count++;
 112         if (i == last_) break;
 113       }
 114       CHECK_EQ(size(), count);
 115       CHECK_EQ(last_->next, 0);
 116     }
 117   }
 118
 119   template<class ListTy, class ItemTy>
 120   class IteratorBase {
 121    public:
 122     explicit IteratorBase(ListTy *list)
 123         : list_(list), current_(list->first_) { }
 124     ItemTy *next() {
 125       ItemTy *ret = current_;
 126       if (current_) current_ = current_->next;
 127       return ret;
 128     }
 129     bool hasNext() const { return current_ != nullptr; }
 130    private:
 131     ListTy *list_;
 132     ItemTy *current_;
 133   };
 134
 135   typedef IteratorBase<IntrusiveList<Item>, Item> Iterator;
 136   typedef IteratorBase<const IntrusiveList<Item>, const Item> ConstIterator;
 137
 138 // private, don't use directly.
 139   uptr size_;
 140   Item *first_;
 141   Item *last_;
 142 };
 143
 144 } // namespace __sanitizer
 145
 146 #endif // SANITIZER_LIST_H