mirror of https://github.com/odrling/Aegisub
296 lines
8.4 KiB
C++
296 lines
8.4 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is Mozilla Universal charset detector code.
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 2001
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Shy Shalom <shooshX@gmail.com>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#include "nscore.h"
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#include "nsUniversalDetector.h"
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#include "nsMBCSGroupProber.h"
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#include "nsSBCSGroupProber.h"
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#include "nsEscCharsetProber.h"
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#include "nsLatin1Prober.h"
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nsUniversalDetector::nsUniversalDetector(PRUint32 aLanguageFilter)
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{
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mDone = PR_FALSE;
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mBestGuess = -1; //illegal value as signal
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mInTag = PR_FALSE;
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mEscCharSetProber = nsnull;
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mStart = PR_TRUE;
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mDetectedCharset = nsnull;
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mGotData = PR_FALSE;
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mInputState = ePureAscii;
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mLastChar = '\0';
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mLanguageFilter = aLanguageFilter;
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PRUint32 i;
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for (i = 0; i < NUM_OF_CHARSET_PROBERS; i++)
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mCharSetProbers[i] = nsnull;
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}
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nsUniversalDetector::~nsUniversalDetector()
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{
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for (PRInt32 i = 0; i < NUM_OF_CHARSET_PROBERS; i++)
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if (mCharSetProbers[i])
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delete mCharSetProbers[i];
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if (mEscCharSetProber)
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delete mEscCharSetProber;
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}
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void
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nsUniversalDetector::Reset()
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{
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mDone = PR_FALSE;
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mBestGuess = -1; //illegal value as signal
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mInTag = PR_FALSE;
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mStart = PR_TRUE;
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mDetectedCharset = nsnull;
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mGotData = PR_FALSE;
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mInputState = ePureAscii;
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mLastChar = '\0';
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if (mEscCharSetProber)
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mEscCharSetProber->Reset();
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PRUint32 i;
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for (i = 0; i < NUM_OF_CHARSET_PROBERS; i++)
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if (mCharSetProbers[i])
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mCharSetProbers[i]->Reset();
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}
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//---------------------------------------------------------------------
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#define SHORTCUT_THRESHOLD (float)0.95
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#define MINIMUM_THRESHOLD (float)0.20
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nsresult nsUniversalDetector::HandleData(const char* aBuf, PRUint32 aLen)
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{
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if(mDone)
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return NS_OK;
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if (aLen > 0)
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mGotData = PR_TRUE;
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//If the data starts with BOM, we know it is UTF
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if (mStart)
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{
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mStart = PR_FALSE;
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if (aLen > 3)
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switch (aBuf[0])
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{
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case '\xEF':
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if (('\xBB' == aBuf[1]) && ('\xBF' == aBuf[2]))
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// EF BB BF UTF-8 encoded BOM
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mDetectedCharset = "UTF-8";
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break;
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case '\xFE':
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if (('\xFF' == aBuf[1]) && ('\x00' == aBuf[2]) && ('\x00' == aBuf[3]))
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// FE FF 00 00 UCS-4, unusual octet order BOM (3412)
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mDetectedCharset = "X-ISO-10646-UCS-4-3412";
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else if ('\xFF' == aBuf[1])
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// FE FF UTF-16, big endian BOM
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mDetectedCharset = "UTF-16BE";
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break;
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case '\x00':
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if (('\x00' == aBuf[1]) && ('\xFE' == aBuf[2]) && ('\xFF' == aBuf[3]))
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// 00 00 FE FF UTF-32, big-endian BOM
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mDetectedCharset = "UTF-32BE";
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else if (('\x00' == aBuf[1]) && ('\xFF' == aBuf[2]) && ('\xFE' == aBuf[3]))
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// 00 00 FF FE UCS-4, unusual octet order BOM (2143)
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mDetectedCharset = "X-ISO-10646-UCS-4-2143";
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break;
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case '\xFF':
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if (('\xFE' == aBuf[1]) && ('\x00' == aBuf[2]) && ('\x00' == aBuf[3]))
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// FF FE 00 00 UTF-32, little-endian BOM
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mDetectedCharset = "UTF-32LE";
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else if ('\xFE' == aBuf[1])
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// FF FE UTF-16, little endian BOM
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mDetectedCharset = "UTF-16LE";
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break;
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} // switch
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if (mDetectedCharset)
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{
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mDone = PR_TRUE;
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return NS_OK;
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}
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}
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PRUint32 i;
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for (i = 0; i < aLen; i++)
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{
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//other than 0xa0, if every othe character is ascii, the page is ascii
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if (aBuf[i] & '\x80' && aBuf[i] != '\xA0') //Since many Ascii only page contains NBSP
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{
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//we got a non-ascii byte (high-byte)
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if (mInputState != eHighbyte)
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{
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//adjust state
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mInputState = eHighbyte;
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//kill mEscCharSetProber if it is active
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if (mEscCharSetProber) {
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delete mEscCharSetProber;
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mEscCharSetProber = nsnull;
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}
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//start multibyte and singlebyte charset prober
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if (nsnull == mCharSetProbers[0])
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{
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mCharSetProbers[0] = new nsMBCSGroupProber(mLanguageFilter);
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if (nsnull == mCharSetProbers[0])
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return NS_ERROR_OUT_OF_MEMORY;
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}
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if (nsnull == mCharSetProbers[1] &&
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(mLanguageFilter & NS_FILTER_NON_CJK))
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{
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mCharSetProbers[1] = new nsSBCSGroupProber;
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if (nsnull == mCharSetProbers[1])
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return NS_ERROR_OUT_OF_MEMORY;
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}
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if (nsnull == mCharSetProbers[2])
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{
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mCharSetProbers[2] = new nsLatin1Prober;
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if (nsnull == mCharSetProbers[2])
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return NS_ERROR_OUT_OF_MEMORY;
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}
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}
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}
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else
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{
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//ok, just pure ascii so far
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if ( ePureAscii == mInputState &&
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(aBuf[i] == '\033' || (aBuf[i] == '{' && mLastChar == '~')) )
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{
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//found escape character or HZ "~{"
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mInputState = eEscAscii;
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}
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mLastChar = aBuf[i];
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}
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}
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nsProbingState st;
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switch (mInputState)
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{
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case eEscAscii:
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if (nsnull == mEscCharSetProber) {
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mEscCharSetProber = new nsEscCharSetProber(mLanguageFilter);
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if (nsnull == mEscCharSetProber)
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return NS_ERROR_OUT_OF_MEMORY;
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}
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st = mEscCharSetProber->HandleData(aBuf, aLen);
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if (st == eFoundIt)
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{
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mDone = PR_TRUE;
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mDetectedCharset = mEscCharSetProber->GetCharSetName();
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}
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break;
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case eHighbyte:
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for (i = 0; i < NUM_OF_CHARSET_PROBERS; i++)
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{
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if (mCharSetProbers[i])
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{
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st = mCharSetProbers[i]->HandleData(aBuf, aLen);
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if (st == eFoundIt)
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{
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mDone = PR_TRUE;
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mDetectedCharset = mCharSetProbers[i]->GetCharSetName();
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return NS_OK;
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}
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}
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}
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break;
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default: //pure ascii
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;//do nothing here
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}
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return NS_OK;
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}
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//---------------------------------------------------------------------
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void nsUniversalDetector::DataEnd()
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{
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if (!mGotData)
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{
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// we haven't got any data yet, return immediately
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// caller program sometimes call DataEnd before anything has been sent to detector
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return;
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}
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if (mDetectedCharset)
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{
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mDone = PR_TRUE;
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Report(mDetectedCharset);
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return;
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}
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switch (mInputState)
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{
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case eHighbyte:
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{
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float proberConfidence;
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float maxProberConfidence = (float)0.0;
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PRInt32 maxProber = 0;
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for (PRInt32 i = 0; i < NUM_OF_CHARSET_PROBERS; i++)
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{
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if (mCharSetProbers[i])
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{
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proberConfidence = mCharSetProbers[i]->GetConfidence();
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if (proberConfidence > maxProberConfidence)
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{
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maxProberConfidence = proberConfidence;
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maxProber = i;
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}
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}
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}
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//do not report anything because we are not confident of it, that's in fact a negative answer
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if (maxProberConfidence > MINIMUM_THRESHOLD)
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Report(mCharSetProbers[maxProber]->GetCharSetName());
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}
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break;
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case eEscAscii:
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break;
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default:
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;
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}
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return;
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}
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