JpCntx.h

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#ifndef __JPCNTX_H__
#define __JPCNTX_H__

#include "kdemacros.h"

#define NUM_OF_CATEGORY 6

#define ENOUGH_REL_THRESHOLD  100
#define MAX_REL_THRESHOLD     1000
namespace kencodingprober {
//hiragana frequency category table
extern const char jp2CharContext[83][83];

class KDE_NO_EXPORT JapaneseContextAnalysis
{
public:
  JapaneseContextAnalysis() {Reset();};
  virtual ~JapaneseContextAnalysis() {};

  void HandleData(const char* aBuf, unsigned int aLen);

  void HandleOneChar(const char* aStr, unsigned int aCharLen)
  {
    int order;

    //if we received enough data, stop here   
    if (mTotalRel > MAX_REL_THRESHOLD)   mDone = true;
    if (mDone)       return;
     
    //Only 2-bytes characters are of our interest
    order = (aCharLen == 2) ? GetOrder(aStr) : -1;
    if (order != -1 && mLastCharOrder != -1)
    {
      mTotalRel++;
      //count this sequence to its category counter
      mRelSample[(int)jp2CharContext[mLastCharOrder][order]]++;
    }
    mLastCharOrder = order;
  };

  float GetConfidence();
  void      Reset(void);
  void      SetOpion(){};
  bool GotEnoughData() {return mTotalRel > ENOUGH_REL_THRESHOLD;};

protected:
  virtual int GetOrder(const char* str, unsigned int *charLen) = 0;
  virtual int GetOrder(const char* str) = 0;

  //category counters, each interger counts sequence in its category
  unsigned int mRelSample[NUM_OF_CATEGORY];

  //total sequence received
  unsigned int mTotalRel;
  
  //The order of previous char
  int  mLastCharOrder;

  //if last byte in current buffer is not the last byte of a character, we
  //need to know how many byte to skip in next buffer.
  unsigned int mNeedToSkipCharNum;

  //If this flag is set to true, detection is done and conclusion has been made
  bool   mDone;
};


class KDE_NO_EXPORT SJISContextAnalysis : public JapaneseContextAnalysis
{
  //SJISContextAnalysis(){};
protected:
  int GetOrder(const char* str, unsigned int *charLen);

  int GetOrder(const char* str)
  {
    //We only interested in Hiragana, so first byte is '\202'
    if (*str == '\202' && 
          (unsigned char)*(str+1) >= (unsigned char)0x9f && 
          (unsigned char)*(str+1) <= (unsigned char)0xf1)
      return (unsigned char)*(str+1) - (unsigned char)0x9f;
    return -1;
  };
};

class KDE_NO_EXPORT EUCJPContextAnalysis : public JapaneseContextAnalysis
{
protected:
  int GetOrder(const char* str, unsigned int *charLen);
  int GetOrder(const char* str)
    //We only interested in Hiragana, so first byte is '\244'
  {
    if (*str == '\244' &&
          (unsigned char)*(str+1) >= (unsigned char)0xa1 &&
          (unsigned char)*(str+1) <= (unsigned char)0xf3)
      return (unsigned char)*(str+1) - (unsigned char)0xa1;
    return -1;
  };
};
}
#endif /* __JPCNTX_H__ */