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      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   const Item *front() const { return first_; }
     75   Item *back() { return last_; }
     76   const Item *back() const { return last_; }
     77 
     78   void append_front(IntrusiveList<Item> *l) {
     79     CHECK_NE(this, l);
     80     if (l->empty())
     81       return;
     82     if (empty()) {
     83       *this = *l;
     84     } else if (!l->empty()) {
     85       l->last_->next = first_;
     86       first_ = l->first_;
     87       size_ += l->size();
     88     }
     89     l->clear();
     90   }
     91 
     92   void append_back(IntrusiveList<Item> *l) {
     93     CHECK_NE(this, l);
     94     if (l->empty())
     95       return;
     96     if (empty()) {
     97       *this = *l;
     98     } else {
     99       last_->next = l->first_;
    100       last_ = l->last_;
    101       size_ += l->size();
    102     }
    103     l->clear();
    104   }
    105 
    106   void CheckConsistency() {
    107     if (size_ == 0) {
    108       CHECK_EQ(first_, 0);
    109       CHECK_EQ(last_, 0);
    110     } else {
    111       uptr count = 0;
    112       for (Item *i = first_; ; i = i->next) {
    113         count++;
    114         if (i == last_) break;
    115       }
    116       CHECK_EQ(size(), count);
    117       CHECK_EQ(last_->next, 0);
    118     }
    119   }
    120 
    121   template<class ItemTy>
    122   class IteratorBase {
    123    public:
    124     explicit IteratorBase(ItemTy *current) : current_(current) {}
    125     IteratorBase &operator++() {
    126       current_ = current_->next;
    127       return *this;
    128     }
    129     bool operator!=(IteratorBase other) const {
    130       return current_ != other.current_;
    131     }
    132     ItemTy &operator*() {
    133       return *current_;
    134     }
    135    private:
    136     ItemTy *current_;
    137   };
    138 
    139   typedef IteratorBase<Item> Iterator;
    140   typedef IteratorBase<const Item> ConstIterator;
    141 
    142   Iterator begin() { return Iterator(first_); }
    143   Iterator end() { return Iterator(0); }
    144 
    145   ConstIterator begin() const { return ConstIterator(first_); }
    146   ConstIterator end() const { return ConstIterator(0); }
    147 
    148 // private, don't use directly.
    149   uptr size_;
    150   Item *first_;
    151   Item *last_;
    152 };
    153 
    154 } // namespace __sanitizer
    155 
    156 #endif // SANITIZER_LIST_H
    157