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/* -*- Mode: C; tab-width: 4; 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
* Shy Shalom <shooshX@gmail.com>
* Portions created by the Initial Developer are Copyright (C) 2005
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* 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 "nsHebrewProber.h"
#include <stdio.h>
// windows-1255 / ISO-8859-8 code points of interest
#define FINAL_KAF ('\xea')
#define NORMAL_KAF ('\xeb')
#define FINAL_MEM ('\xed')
#define NORMAL_MEM ('\xee')
#define FINAL_NUN ('\xef')
#define NORMAL_NUN ('\xf0')
#define FINAL_PE ('\xf3')
#define NORMAL_PE ('\xf4')
#define FINAL_TSADI ('\xf5')
#define NORMAL_TSADI ('\xf6')
// Minimum Visual vs Logical final letter score difference.
// If the difference is below this, don't rely solely on the final letter score distance.
#define MIN_FINAL_CHAR_DISTANCE (5)
// Minimum Visual vs Logical model score difference.
// If the difference is below this, don't rely at all on the model score distance.
#define MIN_MODEL_DISTANCE (0.01)
#define VISUAL_HEBREW_NAME ("ISO-8859-8")
#define LOGICAL_HEBREW_NAME ("WINDOWS-1255")
PRBool nsHebrewProber::isFinal(char c)
{
return ((c == FINAL_KAF) || (c == FINAL_MEM) || (c == FINAL_NUN) || (c == FINAL_PE) || (c == FINAL_TSADI));
}
PRBool nsHebrewProber::isNonFinal(char c)
{
return ((c == NORMAL_KAF) || (c == NORMAL_MEM) || (c == NORMAL_NUN) || (c == NORMAL_PE));
// The normal Tsadi is not a good Non-Final letter due to words like
// 'lechotet' (to chat) containing an apostrophe after the tsadi. This
// apostrophe is converted to a space in FilterWithoutEnglishLetters causing
// the Non-Final tsadi to appear at an end of a word even though this is not
// the case in the original text.
// The letters Pe and Kaf rarely display a related behavior of not being a
// good Non-Final letter. Words like 'Pop', 'Winamp' and 'Mubarak' for
// example legally end with a Non-Final Pe or Kaf. However, the benefit of
// these letters as Non-Final letters outweighs the damage since these words
// are quite rare.
}
/** HandleData
* Final letter analysis for logical-visual decision.
* Look for evidence that the received buffer is either logical Hebrew or
* visual Hebrew.
* The following cases are checked:
* 1) A word longer than 1 letter, ending with a final letter. This is an
* indication that the text is laid out "naturally" since the final letter
* really appears at the end. +1 for logical score.
* 2) A word longer than 1 letter, ending with a Non-Final letter. In normal
* Hebrew, words ending with Kaf, Mem, Nun, Pe or Tsadi, should not end with
* the Non-Final form of that letter. Exceptions to this rule are mentioned
* above in isNonFinal(). This is an indication that the text is laid out
* backwards. +1 for visual score
* 3) A word longer than 1 letter, starting with a final letter. Final letters
* should not appear at the beginning of a word. This is an indication that
* the text is laid out backwards. +1 for visual score.
*
* The visual score and logical score are accumulated throughout the text and
* are finally checked against each other in GetCharSetName().
* No checking for final letters in the middle of words is done since that case
* is not an indication for either Logical or Visual text.
*
* The input buffer should not contain any white spaces that are not (' ')
* or any low-ascii punctuation marks.
*/
nsProbingState nsHebrewProber::HandleData(const char* aBuf, PRUint32 aLen)
{
// Both model probers say it's not them. No reason to continue.
if (GetState() == eNotMe)
return eNotMe;
const char *curPtr, *endPtr = aBuf+aLen;
char cur;
for (curPtr = (char*)aBuf; curPtr < endPtr; ++curPtr)
{
cur = *curPtr;
if (cur == ' ') // We stand on a space - a word just ended
{
if (mBeforePrev != ' ') // *(curPtr-2) was not a space so prev is not a 1 letter word
{
if (isFinal(mPrev)) // case (1) [-2:not space][-1:final letter][cur:space]
++mFinalCharLogicalScore;
else if (isNonFinal(mPrev)) // case (2) [-2:not space][-1:Non-Final letter][cur:space]
++mFinalCharVisualScore;
}
}
else // Not standing on a space
{
if ((mBeforePrev == ' ') && (isFinal(mPrev)) && (cur != ' ')) // case (3) [-2:space][-1:final letter][cur:not space]
++mFinalCharVisualScore;
}
mBeforePrev = mPrev;
mPrev = cur;
}
// Forever detecting, till the end or until both model probers return eNotMe (handled above).
return eDetecting;
}
// Make the decision: is it Logical or Visual?
const char* nsHebrewProber::GetCharSetName()
{
// If the final letter score distance is dominant enough, rely on it.
PRInt32 finalsub = mFinalCharLogicalScore - mFinalCharVisualScore;
if (finalsub >= MIN_FINAL_CHAR_DISTANCE)
return LOGICAL_HEBREW_NAME;
if (finalsub <= -(MIN_FINAL_CHAR_DISTANCE))
return VISUAL_HEBREW_NAME;
// It's not dominant enough, try to rely on the model scores instead.
float modelsub = mLogicalProb->GetConfidence() - mVisualProb->GetConfidence();
if (modelsub > MIN_MODEL_DISTANCE)
return LOGICAL_HEBREW_NAME;
if (modelsub < -(MIN_MODEL_DISTANCE))
return VISUAL_HEBREW_NAME;
// Still no good, back to final letter distance, maybe it'll save the day.
if (finalsub < 0)
return VISUAL_HEBREW_NAME;
// (finalsub > 0 - Logical) or (don't know what to do) default to Logical.
return LOGICAL_HEBREW_NAME;
}
void nsHebrewProber::Reset(void)
{
mFinalCharLogicalScore = 0;
mFinalCharVisualScore = 0;
// mPrev and mBeforePrev are initialized to space in order to simulate a word
// delimiter at the beginning of the data
mPrev = ' ';
mBeforePrev = ' ';
}
nsProbingState nsHebrewProber::GetState(void)
{
// Remain active as long as any of the model probers are active.
if ((mLogicalProb->GetState() == eNotMe) && (mVisualProb->GetState() == eNotMe))
return eNotMe;
return eDetecting;
}
#ifdef DEBUG_chardet
void nsHebrewProber::DumpStatus()
{
printf(" HEB: %d - %d [Logical-Visual score]\r\n", mFinalCharLogicalScore, mFinalCharVisualScore);
}
#endif
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