Line data    Source code

       1             : /* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* This Source Code Form is subject to the terms of the Mozilla Public
       3             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       4             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       5             : 
       6             : // for S-JIS encoding, obeserve characteristic:
       7             : // 1, kana character (or hankaku?) often have hight frequency of appereance
       8             : // 2, kana character often exist in group
       9             : // 3, certain combination of kana is never used in japanese language
      10             : 
      11             : #include "nsSJISProber.h"
      12             : #include "nsDebug.h"
      13             : 
      14           0 : void  nsSJISProber::Reset(void)
      15             : {
      16           0 :   mCodingSM->Reset();
      17           0 :   mState = eDetecting;
      18           0 :   mContextAnalyser.Reset();
      19           0 :   mDistributionAnalyser.Reset();
      20           0 : }
      21             : 
      22           0 : nsProbingState nsSJISProber::HandleData(const char* aBuf, uint32_t aLen)
      23             : {
      24           0 :   NS_ASSERTION(aLen, "HandleData called with empty buffer");
      25             :   nsSMState codingState;
      26             : 
      27           0 :   for (uint32_t i = 0; i < aLen; i++)
      28             :   {
      29           0 :     codingState = mCodingSM->NextState(aBuf[i]);
      30           0 :     if (codingState == eItsMe)
      31             :     {
      32           0 :       mState = eFoundIt;
      33           0 :       break;
      34             :     }
      35           0 :     if (codingState == eStart)
      36             :     {
      37           0 :       uint32_t charLen = mCodingSM->GetCurrentCharLen();
      38           0 :       if (i == 0)
      39             :       {
      40           0 :         mLastChar[1] = aBuf[0];
      41           0 :         mContextAnalyser.HandleOneChar(mLastChar+2-charLen, charLen);
      42           0 :         mDistributionAnalyser.HandleOneChar(mLastChar, charLen);
      43             :       }
      44             :       else
      45             :       {
      46           0 :         mContextAnalyser.HandleOneChar(aBuf+i+1-charLen, charLen);
      47           0 :         mDistributionAnalyser.HandleOneChar(aBuf+i-1, charLen);
      48             :       }
      49             :     }
      50             :   }
      51             : 
      52           0 :   mLastChar[0] = aBuf[aLen-1];
      53             : 
      54           0 :   if (mState == eDetecting)
      55           0 :     if (mContextAnalyser.GotEnoughData() && GetConfidence() > SHORTCUT_THRESHOLD)
      56           0 :       mState = eFoundIt;
      57             : 
      58           0 :   return mState;
      59             : }
      60             : 
      61           0 : float nsSJISProber::GetConfidence(void)
      62             : {
      63           0 :   float contxtCf = mContextAnalyser.GetConfidence();
      64           0 :   float distribCf = mDistributionAnalyser.GetConfidence();
      65             : 
      66           0 :   return (contxtCf > distribCf ? contxtCf : distribCf);
      67             : }
      68             :