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28 
29 // static_map.h: StaticMap.
30 //
31 // StaticMap provides lookup interfaces and iterators similar as stl::map's.
32 // These lookup operations are purely Read-Only, thus memory
33 // allocation & deallocation is mostly avoided (intentionally).
34 //
35 // The chunk of memory should contain data with pre-defined pattern:
36 // **************** header ***************
37 // uint32 (4 bytes): number of nodes
38 // uint32 (4 bytes): address offset of node1's mapped_value
39 // uint32 (4 bytes): address offset of node2's mapped_value
40 // ...
41 // uint32 (4 bytes): address offset of nodeN's mapped_value
42 //
43 // ************* Key array ************
44 // (X bytes): node1's key
45 // (X bytes): node2's key
46 // ...
47 // (X bytes): nodeN's key
48 //
49 // ************* Value array **********
50 // (? bytes): node1's mapped_value
51 // (? bytes): node2's mapped_value
52 // ...
53 // (? bytes): nodeN's mapped_value
54 //
55 // REQUIREMENT: Key type MUST be primitive type or pointers so that:
56 // X = sizeof(typename Key);
57 //
58 // Note: since address offset is stored as uint32, user should keep in mind that
59 // StaticMap only supports up to 4GB size of memory data.
60 
61 // Author: Siyang Xie (lambxsy@google.com)
62 
63 
64 #ifndef PROCESSOR_STATIC_MAP_H__
65 #define PROCESSOR_STATIC_MAP_H__
66 
67 #include "processor/static_map_iterator-inl.h"
68 
69 namespace google_breakpad {
70 
71 // Default functor to compare keys.
72 template<typename Key>
73 class DefaultCompare {
74  public:
operator()75   int operator()(const Key &k1, const Key &k2) const {
76     if (k1 < k2) return -1;
77     if (k1 == k2) return 0;
78     return 1;
79   }
80 };
81 
82 template<typename Key, typename Value, typename Compare = DefaultCompare<Key> >
83 class StaticMap {
84  public:
85   typedef StaticMapIterator<Key, Value, Compare> iterator;
86   typedef StaticMapIterator<Key, Value, Compare> const_iterator;
87 
StaticMap()88   StaticMap() : raw_data_(0),
89                 num_nodes_(0),
90                 offsets_(0),
91                 compare_() { }
92 
93   explicit StaticMap(const char* raw_data);
94 
empty()95   inline bool empty() const { return num_nodes_ == 0; }
size()96   inline unsigned int size() const { return num_nodes_; }
97 
98   // Return iterators.
begin()99   inline iterator begin() const { return IteratorAtIndex(0); }
last()100   inline iterator last() const { return IteratorAtIndex(num_nodes_ - 1); }
end()101   inline iterator end() const { return IteratorAtIndex(num_nodes_); }
IteratorAtIndex(int index)102   inline iterator IteratorAtIndex(int index) const {
103     return iterator(raw_data_, index);
104   }
105 
106   // Lookup operations.
107   iterator find(const Key &k) const;
108 
109   // lower_bound(k) searches in a sorted range for the first element that has a
110   // key not less than the argument k.
111   iterator lower_bound(const Key &k) const;
112 
113   // upper_bound(k) searches in a sorted range for the first element that has a
114   // key greater than the argument k.
115   iterator upper_bound(const Key &k) const;
116 
117   // Checks if the underlying memory data conforms to the predefined pattern:
118   // first check the number of nodes is non-negative,
119   // then check both offsets and keys are strictly increasing (sorted).
120   bool ValidateInMemoryStructure() const;
121 
122  private:
123   const Key GetKeyAtIndex(int i) const;
124 
125   // Start address of a raw memory chunk with serialized data.
126   const char* raw_data_;
127 
128   // Number of nodes in the static map.
129   int32_t num_nodes_;
130 
131   // Array of offset addresses for stored values.
132   // For example:
133   // address_of_i-th_node_value = raw_data_ + offsets_[i]
134   const uint32_t* offsets_;
135 
136   // keys_[i] = key of i_th node
137   const Key* keys_;
138 
139   Compare compare_;
140 };
141 
142 }  // namespace google_breakpad
143 
144 #endif  // PROCESSOR_STATIC_MAP_H__
145