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/extensions/universalchardet/src/base/nsSJISProber.cpp

http://github.com/zpao/v8monkey
C++ | 100 lines | 49 code | 11 blank | 40 comment | 11 complexity | b9b9041da9309a69d3df36ae3c9849eb MD5 | raw file
  1/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
  2/* ***** BEGIN LICENSE BLOCK *****
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 37
 38// for S-JIS encoding, obeserve characteristic:
 39// 1, kana character (or hankaku?) often have hight frequency of appereance
 40// 2, kana character often exist in group
 41// 3, certain combination of kana is never used in japanese language
 42
 43#include "nsSJISProber.h"
 44#include "nsDebug.h"
 45
 46void  nsSJISProber::Reset(void)
 47{
 48  mCodingSM->Reset(); 
 49  mState = eDetecting;
 50  mContextAnalyser.Reset(mIsPreferredLanguage);
 51  mDistributionAnalyser.Reset(mIsPreferredLanguage);
 52}
 53
 54nsProbingState nsSJISProber::HandleData(const char* aBuf, PRUint32 aLen)
 55{
 56  NS_ASSERTION(aLen, "HandleData called with empty buffer");
 57  nsSMState codingState;
 58
 59  for (PRUint32 i = 0; i < aLen; i++)
 60  {
 61    codingState = mCodingSM->NextState(aBuf[i]);
 62    if (codingState == eItsMe)
 63    {
 64      mState = eFoundIt;
 65      break;
 66    }
 67    if (codingState == eStart)
 68    {
 69      PRUint32 charLen = mCodingSM->GetCurrentCharLen();
 70      if (i == 0)
 71      {
 72        mLastChar[1] = aBuf[0];
 73        mContextAnalyser.HandleOneChar(mLastChar+2-charLen, charLen);
 74        mDistributionAnalyser.HandleOneChar(mLastChar, charLen);
 75      }
 76      else
 77      {
 78        mContextAnalyser.HandleOneChar(aBuf+i+1-charLen, charLen);
 79        mDistributionAnalyser.HandleOneChar(aBuf+i-1, charLen);
 80      }
 81    }
 82  }
 83
 84  mLastChar[0] = aBuf[aLen-1];
 85
 86  if (mState == eDetecting)
 87    if (mContextAnalyser.GotEnoughData() && GetConfidence() > SHORTCUT_THRESHOLD)
 88      mState = eFoundIt;
 89
 90  return mState;
 91}
 92
 93float nsSJISProber::GetConfidence(void)
 94{
 95  float contxtCf = mContextAnalyser.GetConfidence();
 96  float distribCf = mDistributionAnalyser.GetConfidence();
 97
 98  return (contxtCf > distribCf ? contxtCf : distribCf);
 99}
100