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// Mozc system dictionary

#ifndef MOZC_DICTIONARY_SYSTEM_SYSTEM_DICTIONARY_H_
#define MOZC_DICTIONARY_SYSTEM_SYSTEM_DICTIONARY_H_

#include <map>
#include <set>
#include <string>
#include <vector>

#include "base/port.h"
#include "base/scoped_ptr.h"
#include "base/string_piece.h"
#include "dictionary/dictionary_interface.h"
#include "dictionary/system/codec_interface.h"
#include "dictionary/system/key_expansion_table.h"
#include "dictionary/system/words_info.h"
#include "storage/louds/bit_vector_based_array.h"
#include "storage/louds/louds_trie.h"

namespace mozc {

class DictionaryFile;

namespace dictionary {

class SystemDictionaryCodecInterface;
class ReverseLookupIndex;

class SystemDictionary : public DictionaryInterface {
 public:
  // System dictionary options represented as bitwise enum.
  enum Options {
    NONE = 0,
    // If ENABLE_REVERSE_LOOKUP_INDEX is set, we will have the index in heap
    // from the id in value trie to the id in key trie.
    // That consumes more memory but we can perform reverse lookup more quickly.
    ENABLE_REVERSE_LOOKUP_INDEX = 1,
  };

  // Builder class for system dictionary
  // Usage:
  //   SystemDictionary::Builder builder(filename);
  //   builder.SetOptions(SystemDictionary::NONE);
  //   builder.SetCodec(NULL);
  //   SystemDictionary *dictionry = builder.Build();
  class Builder {
   public:
    // Creates Builder from filename
    explicit Builder(const string &filename);
    // Creates Builder from image
    Builder(const char *ptr, int len);
    ~Builder();

    // Sets options (default: NONE)
    Builder &SetOptions(Options options);

    // Sets codec (default: NULL)
    // Uses default codec if this is NULL
    // Doesn't take the ownership of |codec|.
    Builder &SetCodec(const SystemDictionaryCodecInterface *codec);

    // Builds and returns system dictionary.
    SystemDictionary *Build();

   private:
    enum InputType {
      FILENAME,
      IMAGE,
    };

    InputType type_;

    // For InputType::FILENAME
    const string filename_;

    // For InputTYpe::IMAGE
    const char *ptr_;
    const int len_;

    Options options_;
    const SystemDictionaryCodecInterface *codec_;

    DISALLOW_COPY_AND_ASSIGN(Builder);
  };

  virtual ~SystemDictionary();

  // Implementation of DictionaryInterface.
  virtual bool HasKey(StringPiece key) const;
  virtual bool HasValue(StringPiece value) const;
  virtual void LookupPredictive(
      StringPiece key, bool use_kana_modifier_insensitive_lookup,
      Callback *callback) const;
  virtual void LookupPrefix(
      StringPiece key, bool use_kana_modifier_insensitive_lookup,
      Callback *callback) const;
  virtual void LookupExact(StringPiece key, Callback *callback) const;
  virtual void LookupReverse(StringPiece str, NodeAllocatorInterface *allocator,
                             Callback *callback) const;
  virtual void PopulateReverseLookupCache(
      StringPiece str, NodeAllocatorInterface *allocator) const;
  virtual void ClearReverseLookupCache(
      NodeAllocatorInterface *allocator) const;

  // TODO(noriyukit): This structure is implementation detail so should be
  // hidden.
  struct ReverseLookupResult {
    ReverseLookupResult() : tokens_offset(-1), id_in_key_trie(-1) {}
    // Offset from the tokens section beginning.
    // (token_array_.Get(id_in_key_trie) == token_array_.Get(0) + tokens_offset)
    int tokens_offset;
    // Id in key trie
    int id_in_key_trie;
  };

 private:
  explicit SystemDictionary(const SystemDictionaryCodecInterface *codec);
  bool OpenDictionaryFile(bool enable_reverse_lookup_index);

  void RegisterReverseLookupTokensForT13N(StringPiece value,
                                          Callback *callback) const;
  void RegisterReverseLookupTokensForValue(StringPiece value,
                                           NodeAllocatorInterface *allocator,
                                           Callback *callback) const;
  void ScanTokens(const set<int> &id_set,
                  multimap<int, ReverseLookupResult> *reverse_results) const;
  void RegisterReverseLookupResults(
      const set<int> &id_set,
      const multimap<int, ReverseLookupResult> &reverse_results,
      Callback *callback) const;
  void InitReverseLookupIndex();

  Callback::ResultType LookupPrefixWithKeyExpansionImpl(
      const char *key,
      StringPiece encoded_key,
      const KeyExpansionTable &table,
      Callback *callback,
      storage::louds::LoudsTrie::Node node,
      StringPiece::size_type key_pos,
      bool is_expanded,
      char *actual_key_buffer,
      string *actual_prefix) const;

  struct PredictiveLookupSearchState {
    PredictiveLookupSearchState() : key_pos(0), is_expanded(false) {}
    PredictiveLookupSearchState(const storage::louds::LoudsTrie::Node &n,
                                size_t pos, bool expanded)
        : node(n), key_pos(pos), is_expanded(expanded) {}

    storage::louds::LoudsTrie::Node node;
    size_t key_pos;
    bool is_expanded;
  };

  void CollectPredictiveNodesInBfsOrder(
      StringPiece encoded_key,
      const KeyExpansionTable &table,
      size_t limit,
      vector<PredictiveLookupSearchState> *result) const;

  storage::louds::LoudsTrie key_trie_;
  storage::louds::LoudsTrie value_trie_;
  storage::louds::BitVectorBasedArray token_array_;
  const uint32 *frequent_pos_;
  const SystemDictionaryCodecInterface *codec_;
  KeyExpansionTable hiragana_expansion_table_;
  scoped_ptr<DictionaryFile> dictionary_file_;
  scoped_ptr<ReverseLookupIndex> reverse_lookup_index_;

  DISALLOW_COPY_AND_ASSIGN(SystemDictionary);
};

}  // namespace dictionary
}  // namespace mozc

#endif  // MOZC_DICTIONARY_SYSTEM_SYSTEM_DICTIONARY_H_