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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   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
    147