text: // Copyright 2010-2016, Google Inc.
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  #ifndef MOZC_CONVERTER_KEY_CORRECTOR_H_
  #define MOZC_CONVERTER_KEY_CORRECTOR_H_
  
  #include <string>
  #include <vector>
  
  #include "base/port.h"
  
  namespace mozc {
  
  class KeyCorrector {
   public:
    enum InputMode {
      ROMAN,
      KANA,
    };
  
    KeyCorrector(const string &key, InputMode mode, size_t history_size);
    KeyCorrector();
    virtual ~KeyCorrector();
  
    InputMode mode() const;
  
    bool CorrectKey(const string &key, InputMode mode, size_t history_size);
  
    // return corrected key;
    const string &corrected_key() const;
  
    // return original key;
    const string &original_key() const;
  
    // return true key correction was done successfully
    bool IsAvailable() const;
  
    // return the poistion of corrected_key correspoinding
    // to the original_key_pos
    // return InvalidPosition() if invalid pos is passed.
    // Note that the position is not by Unicode Character but by bytes.
    size_t GetCorrectedPosition(size_t original_key_pos) const;
  
    // return the poistion of original_key correspoinding
    // to the corrected_key_pos
    // return InvalidPosition() if invalid pos is passed.
    // Note that the position is not by Unicode Character but by bytes.
    size_t GetOriginalPosition(size_t corrected_key_pos) const;
  
    // return true if pos is NOT kInvalidPos
    static bool IsValidPosition(size_t pos);
  
    // return true if pos is kInvalidPos
    static bool IsInvalidPosition(size_t pos);
  
    // return kInvalidPos
    static size_t InvalidPosition();
  
    // return new prefix of string correspoindng to
    // the prefix of the original key at "original_key_pos"
    // if new prefix and original prefix are the same, return NULL.
    // Note that return value won't be NULL terminated.
    // "length" stores the length of return value.
    // We don't allow empty matching (see GetPrefix(15) below)
    //
    // More formally, this function can be defined as:
    // GetNewPrefix(original_key_pos) ==
    //   corrected_key.substr(GetCorrectedPosition(original_key),
    //                        corrected_key.size() -
    //                        GetCorrectedPosition(original_key))
    //
    // Example:
    //  original: "せかいじゅのはっぱ"
    //  corrected: "せかいじゅうのはっぱ"
    //  GetPrefix(0) = "せかいじゅうのはっぱ"
    //  GetPrefix(3) = "かいじゅうのはっぱ"
    //  GetPrefix(9) = "じゅうのはっぱ"
    //  GetPrefix(12) = "ゅうのはっぱ"
    //  GetPrefix(15) = NULL (not "うのはっぱ")
    //                  "う" itself doesn't correspond to the original key,
    //                   so, we don't make a new prefix
    //  GetPrefix(18) = NULL (same as original)
    //
    // Example2:
    //  original: "みんあのほん"
    //  GetPrefix(0) = "みんなのほん"
    //  GetPrefix(3) = "んなのほん"
    //  GetPrefix(9) = "なのほん"
    //  GetPrefix(12) = NULL
    const char *GetCorrectedPrefix(const size_t original_key_pos,
                                   size_t *length) const;
  
    // This is a helper function for CommonPrefixSearch in Converter.
    // Basically it is equivalent to
    // GetOriginalPosition(GetCorrectedPosition(original_key_pos)
    //                     + new_key_offset) - original_key_pos;
    //
    // Usage:
    // const char *corrected_prefix = GetCorrectedPrefix(original_key_pos,
    //                                                   &length);
    // Node *nodes = Lookup(corrected_prefix, length);
    // for node in nodes {
    //   original_offset = GetOriginalOffset(original_key_pos, node->length);
    //   InsertLattice(original_key_pos, original_offset);
    // }
    //
    // Example:
    //  original:  "せかいじゅのはっぱ"
    //  corrected: "せかいじゅうのはっぱ"
    // GetOffset(0, 3) == 3
    // GetOffset(0, 12) == 12
    // GetOffset(0, 15) == 12
    // GetOffset(0, 18) == 15
    //
    // By combining GetCorrectedPrefix() and GetOriginalOffset(),
    // Converter is able to know the position of the lattice
    size_t GetOriginalOffset(const size_t original_key_pos,
                             const size_t new_key_offset) const;
  
  
    // return the cost penalty for the corrected key.
    // The return value is added to the original cost as a penalty.
    static int GetCorrectedCostPenalty(const string &key);
  
    // clear internal data
    void Clear();
  
   private:
    bool available_;
    InputMode mode_;
    string corrected_key_;
    string original_key_;
    vector<size_t> alignment_;
    vector<size_t> rev_alignment_;
  
    DISALLOW_COPY_AND_ASSIGN(KeyCorrector);
  };
  
  }  // namespace mozc
  
  #endif  // MOZC_CONVERTER_KEY_CORRECTOR_H_
  