1 files changed, 194 insertions, 0 deletions
diff --git a/src/ext/libcharsetdetect/mozilla/extensions/universalchardet/src/base/nsHebrewProber.cpp b/src/ext/libcharsetdetect/mozilla/extensions/universalchardet/src/base/nsHebrewProber.cpp
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+++ b/src/ext/libcharsetdetect/mozilla/extensions/universalchardet/src/base/nsHebrewProber.cpp
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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