static_map.h

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// static_map.h: StaticMap.
//
// StaticMap provides lookup interfaces and iterators similar as stl::map's.
// These lookup operations are purely Read-Only, thus memory
// allocation & deallocation is mostly avoided (intentionally).
//
// The chunk of memory should contain data with pre-defined pattern:
// **************** header ***************
// uint32 (4 bytes): number of nodes
// uint32 (4 bytes): address offset of node1's mapped_value
// uint32 (4 bytes): address offset of node2's mapped_value
// ...
// uint32 (4 bytes): address offset of nodeN's mapped_value
//
// ************* Key array ************
// (X bytes): node1's key
// (X bytes): node2's key
// ...
// (X bytes): nodeN's key
//
// ************* Value array **********
// (? bytes): node1's mapped_value
// (? bytes): node2's mapped_value
// ...
// (? bytes): nodeN's mapped_value
//
// REQUIREMENT: Key type MUST be primitive type or pointers so that:
// X = sizeof(typename Key);
//
// Note: since address offset is stored as uint32, user should keep in mind that
// StaticMap only supports up to 4GB size of memory data.

// Author: Siyang Xie (lambxsy@google.com)


#ifndef PROCESSOR_STATIC_MAP_H__
#define PROCESSOR_STATIC_MAP_H__

#include "processor/static_map_iterator-inl.h"

namespace google_breakpad {

// Default functor to compare keys.
template<typename Key>
class DefaultCompare {
 public:
  int operator()(const Key &k1, const Key &k2) const {
    if (k1 < k2) return -1;
    if (k1 == k2) return 0;
    return 1;
  }
};

template<typename Key, typename Value, typename Compare = DefaultCompare<Key> >
class StaticMap {
 public:
  typedef StaticMapIterator<Key, Value, Compare> iterator;
  typedef StaticMapIterator<Key, Value, Compare> const_iterator;

  StaticMap() : raw_data_(0),
                num_nodes_(0),
                offsets_(0),
                compare_() { }

  explicit StaticMap(const char* raw_data);

  inline bool empty() const { return num_nodes_ == 0; }
  inline unsigned int size() const { return num_nodes_; }

  // Return iterators.
  inline iterator begin() const { return IteratorAtIndex(0); }
  inline iterator last() const { return IteratorAtIndex(num_nodes_ - 1); }
  inline iterator end() const { return IteratorAtIndex(num_nodes_); }
  inline iterator IteratorAtIndex(int index) const {
    return iterator(raw_data_, index);
  }

  // Lookup operations.
  iterator find(const Key &k) const;

  // lower_bound(k) searches in a sorted range for the first element that has a
  // key not less than the argument k.
  iterator lower_bound(const Key &k) const;

  // upper_bound(k) searches in a sorted range for the first element that has a
  // key greater than the argument k.
  iterator upper_bound(const Key &k) const;

  // Checks if the underlying memory data conforms to the predefined pattern:
  // first check the number of nodes is non-negative,
  // then check both offsets and keys are strictly increasing (sorted).
  bool ValidateInMemoryStructure() const;

 private:
  const Key GetKeyAtIndex(int i) const;

  // Start address of a raw memory chunk with serialized data.
  const char* raw_data_;

  // Number of nodes in the static map.
  int32_t num_nodes_;

  // Array of offset addresses for stored values.
  // For example:
  // address_of_i-th_node_value = raw_data_ + offsets_[i]
  const uint32_t* offsets_;

  // keys_[i] = key of i_th node
  const Key* keys_;

  Compare compare_;
};

}  // namespace google_breakpad

#endif  // PROCESSOR_STATIC_MAP_H__