File Coverage

src/nsUniversalDetector.cpp

Criterion	Covered	Total	%
statement	57	106	53.7
branch	42	118	35.5
condition			n/a
subroutine			n/a
pod			n/a
total	99	224	44.2

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Universal charset detector code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2001
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
  *          Shy Shalom <[e-mail]>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "nscore.h"

#include "nsUniversalDetector.h"

#include "nsMBCSGroupProber.h"
#include "nsSBCSGroupProber.h"
#include "nsEscCharsetProber.h"
#include "nsLatin1Prober.h"

nsUniversalDetector::nsUniversalDetector()
{
  mDone = PR_FALSE;
  mBestGuess = -1;   //illegal value as signal
  mInTag = PR_FALSE;
  mEscCharSetProber = nsnull;

  mStart = PR_TRUE;
  mDetectedCharset = nsnull;
  mGotData = PR_FALSE;
  mInputState = ePureAscii;
  mLastChar = '\0';

  PRUint32 i;
  for (i = 0; i < NUM_OF_CHARSET_PROBERS; i++)
    mCharSetProbers[i] = nsnull;
}

nsUniversalDetector::~nsUniversalDetector()
{
  for (PRInt32 i = 0; i < NUM_OF_CHARSET_PROBERS; i++)
    if (mCharSetProbers[i])
      delete mCharSetProbers[i];
  if (mEscCharSetProber)
    delete mEscCharSetProber;
}

void
nsUniversalDetector::Reset()
{
  mDone = PR_FALSE;
  mBestGuess = -1;   //illegal value as signal
  mInTag = PR_FALSE;

  mStart = PR_TRUE;
  mDetectedCharset = nsnull;
  mGotData = PR_FALSE;
  mInputState = ePureAscii;
  mLastChar = '\0';

  if (mEscCharSetProber)
    mEscCharSetProber->Reset();

  PRUint32 i;
  for (i = 0; i < NUM_OF_CHARSET_PROBERS; i++)
    if (mCharSetProbers[i])
      mCharSetProbers[i]->Reset();
}

//---------------------------------------------------------------------
#define SHORTCUT_THRESHOLD      (float)0.95
#define MINIMUM_THRESHOLD      (float)0.20

nsresult nsUniversalDetector::HandleData(const char* aBuf, PRUint32 aLen)
{
  if(mDone)
    return NS_OK;

  if (aLen > 0)
    mGotData = PR_TRUE;

  //If the data starts with BOM, we know it is UTF
  if (mStart)
  {
    mStart = PR_FALSE;
    if (aLen > 3)
      switch (aBuf[0])
        {
        case '\xEF':
          if (('\xBB' == aBuf[1]) && ('\xBF' == aBuf[2]))
            // EF BB BF  UTF-8 encoded BOM
            mDetectedCharset = "UTF-8";
        break;
        case '\xFE':
          if (('\xFF' == aBuf[1]) && ('\x00' == aBuf[2]) && ('\x00' == aBuf[3]))
            // FE FF 00 00  UCS-4, unusual octet order BOM (3412)
            mDetectedCharset = "X-ISO-10646-UCS-4-3412";
          else if ('\xFF' == aBuf[1])
            // FE FF  UTF-16, big endian BOM
            mDetectedCharset = "UTF-16BE";
        break;
        case '\x00':
          if (('\x00' == aBuf[1]) && ('\xFE' == aBuf[2]) && ('\xFF' == aBuf[3]))
            // 00 00 FE FF  UTF-32, big-endian BOM
            mDetectedCharset = "UTF-32BE";
          else if (('\x00' == aBuf[1]) && ('\xFF' == aBuf[2]) && ('\xFE' == aBuf[3]))
            // 00 00 FF FE  UCS-4, unusual octet order BOM (2143)
            mDetectedCharset = "X-ISO-10646-UCS-4-2143";
        break;
        case '\xFF':
          if (('\xFE' == aBuf[1]) && ('\x00' == aBuf[2]) && ('\x00' == aBuf[3]))
            // FF FE 00 00  UTF-32, little-endian BOM
            mDetectedCharset = "UTF-32LE";
          else if ('\xFE' == aBuf[1])
            // FF FE  UTF-16, little endian BOM
            mDetectedCharset = "UTF-16LE";
        break;
      }  // switch

      if (mDetectedCharset)
      {
        mDone = PR_TRUE;
        return NS_OK;
      }
  }

  PRUint32 i;
  for (i = 0; i < aLen; i++)
  {
    //other than 0xa0, if every othe character is ascii, the page is ascii
    if (aBuf[i] & '\x80' && aBuf[i] != '\xA0')  //Since many Ascii only page contains NBSP
        {
            //we got a non-ascii byte (high-byte)
            if (mInputState != eHighbyte)
            {
                //adjust state
                mInputState = eHighbyte;

                //kill mEscCharSetProber if it is active
                if (mEscCharSetProber) {
                    delete mEscCharSetProber;
                    mEscCharSetProber = nsnull;
                }

                //start multibyte and singlebyte charset prober
                if (nsnull == mCharSetProbers[0])
                    mCharSetProbers[0] = new nsMBCSGroupProber;
                if (nsnull == mCharSetProbers[1])
                    mCharSetProbers[1] = new nsSBCSGroupProber;
                if (nsnull == mCharSetProbers[2])
                    mCharSetProbers[2] = new nsLatin1Prober;

                if ((nsnull == mCharSetProbers[0]) ||
                        (nsnull == mCharSetProbers[1]) ||
                        (nsnull == mCharSetProbers[2]))
                        return NS_ERROR_OUT_OF_MEMORY;
            }
        }
        else
        {
            //ok, just pure ascii so far
            if ( ePureAscii == mInputState &&
                (aBuf[i] == '\033' || (aBuf[i] == '{' && mLastChar == '~')) )
            {
                //found escape character or HZ "~{"
                mInputState = eEscAscii;
            }
            mLastChar = aBuf[i];
        }
    }

    nsProbingState st;
    switch (mInputState)
    {
    case eEscAscii:
        if (nsnull == mEscCharSetProber) {
            mEscCharSetProber = new nsEscCharSetProber;
            if (nsnull == mEscCharSetProber)
                return NS_ERROR_OUT_OF_MEMORY;
        }
        st = mEscCharSetProber->HandleData(aBuf, aLen);
        if (st == eFoundIt)
        {
            mDone = PR_TRUE;
            mDetectedCharset = mEscCharSetProber->GetCharSetName();
        }
        break;
    case eHighbyte:
        for (i = 0; i < NUM_OF_CHARSET_PROBERS; i++)
        {
            st = mCharSetProbers[i]->HandleData(aBuf, aLen);
            if (st == eFoundIt)
            {
                mDone = PR_TRUE;
                mDetectedCharset = mCharSetProbers[i]->GetCharSetName();
                return NS_OK;
            }
        }
        break;

    default:  //pure ascii
        ;//do nothing here
    }
    return NS_OK;
}


//---------------------------------------------------------------------
void nsUniversalDetector::DataEnd()
{
    if (!mGotData)
    {
        // we haven't got any data yet, return immediately
    // caller program sometimes call DataEnd before anything has been sent to detector
    return;
  }

  if (mDetectedCharset)
  {
    mDone = PR_TRUE;
    Report(mDetectedCharset);
    return;
  }

  switch (mInputState)
  {
  case eHighbyte:
    {
      float proberConfidence;
      float maxProberConfidence = (float)0.0;
      PRInt32 maxProber = 0;

      for (PRInt32 i = 0; i < NUM_OF_CHARSET_PROBERS; i++)
      {
        proberConfidence = mCharSetProbers[i]->GetConfidence();
        if (proberConfidence > maxProberConfidence)
        {
          maxProberConfidence = proberConfidence;
          maxProber = i;
        }
      }
      //do not report anything because we are not confident of it, that's in fact a negative answer
      if (maxProberConfidence > MINIMUM_THRESHOLD)
        Report(mCharSetProbers[maxProber]->GetCharSetName());
    }
    break;
  case eEscAscii:
    break;
  default:
    ;
  }
  return;
}