/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
 * The contents of this file are subject to the Netscape 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/NPL/
 *
 * 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.org code.
 *
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s): 
 *   Pierre Phaneuf <pp@ludusdesign.com>
 */
 

#include "nsDTDUtils.h"
#include "CNavDTD.h" 
#include "nsIParserNode.h" 
#include "nsParserNode.h" 

#include "nsIObserverService.h"
#include "nsIServiceManager.h"

MOZ_DECL_CTOR_COUNTER(nsEntryStack);
MOZ_DECL_CTOR_COUNTER(nsDTDContext);
MOZ_DECL_CTOR_COUNTER(CTokenRecycler);
MOZ_DECL_CTOR_COUNTER(CObserverService); 
 
/**************************************************************************************
  A few notes about how residual style handling is performed:
   
    1. The style stack contains nsTagEntry elements. 
    2. Every tag on the containment stack can have it's own residual style stack.
    3. When a style leaks, it's mParent member is set to the level on the stack where 
       it originated. A node with an mParent of 0 is not opened on tag stack, 
       but is open on stylestack.
    4. An easy way to tell that a container on the element stack is a residual style tag
       is that it's use count is >1.

 **************************************************************************************/


/**
 * Default constructor
 * @update	harishd 04/04/99
 * @update  gess 04/22/99
 */
nsEntryStack::nsEntryStack()  {

  MOZ_COUNT_CTOR(nsEntryStack);
  
  mCapacity=0;
  mCount=0;
  mEntries=0;
}

/**
 * Default destructor
 * @update  harishd 04/04/99
 * @update  gess 04/22/99
 */
nsEntryStack::~nsEntryStack() {

  MOZ_COUNT_DTOR(nsEntryStack);

  if(mEntries) {
    if(0<mCount) {
      PRInt32 anIndex=0;
      for(anIndex=0;anIndex<mCount;anIndex++){
        if(mEntries[anIndex].mStyles)
          delete mEntries[anIndex].mStyles;

        //add code here to recycle the node if you have one...
      
      }
    }
    delete [] mEntries;
    mEntries=0;
  }
  mCount=mCapacity=0;
}


/**
 * Resets state of stack to be empty.
 * @update harishd 04/04/99
 */
void nsEntryStack::Empty(void) {
  mCount=0;
}


/**
 * 
 * @update  gess 04/22/99
 */
void nsEntryStack::EnsureCapacityFor(PRInt32 aNewMax,PRInt32 aShiftOffset) {
  if(mCapacity<aNewMax){ 

    const int kDelta=16;

    PRInt32 theSize = kDelta * ((aNewMax / kDelta) + 1);
    nsTagEntry* temp=new nsTagEntry[theSize]; 
    mCapacity=theSize;

    if(temp){ 
      PRInt32 index=0; 
      for(index=0;index<mCount;index++) {
        temp[aShiftOffset+index]=mEntries[index];
      }
      delete [] mEntries;
      mEntries=temp;
    }
    else{
      //XXX HACK! This is very bad! We failed to get memory.
    }
  } //if
}

/**
 * 
 * @update  gess 04/22/99
 */
void nsEntryStack::Push(const nsIParserNode* aNode,nsEntryStack* aStyleStack) {
  if(aNode) {

    EnsureCapacityFor(mCount+1);

    ((nsCParserNode*)aNode)->mUseCount++;
    ((nsCParserNode*)aNode)->mToken->mUseCount++;

    mEntries[mCount].mTag=(eHTMLTags)aNode->GetNodeType();
    mEntries[mCount].mNode=(nsIParserNode*)aNode;
    mEntries[mCount].mParent=aStyleStack;
    mEntries[mCount++].mStyles=0;
  }
}


/**
 * This method inserts the given node onto the front of this stack
 *
 * @update  gess 11/10/99
 */
void nsEntryStack::PushFront(const nsIParserNode* aNode,nsEntryStack* aStyleStack) {
  if(aNode) {

    if(mCount<mCapacity) {
      PRInt32 index=0; 
      for(index=mCount;index>0;index--) {
        mEntries[index]=mEntries[index-1];
      }
    }
    else EnsureCapacityFor(mCount+1,1);


    ((nsCParserNode*)aNode)->mUseCount++;
    ((nsCParserNode*)aNode)->mToken->mUseCount++;

    mEntries[0].mTag=(eHTMLTags)aNode->GetNodeType();
    mEntries[0].mNode=(nsIParserNode*)aNode;
    mEntries[0].mParent=aStyleStack;
    mEntries[0].mStyles=0;
    mCount++;
  }
}

/**
 * 
 * @update  gess 11/10/99
 */
void nsEntryStack::Append(nsEntryStack *aStack) {
  if(aStack) {

    PRInt32 theCount=aStack->mCount;

    EnsureCapacityFor(mCount+aStack->mCount,0);

    PRInt32 theIndex=0;
    for(theIndex=0;theIndex<theCount;theIndex++){
      mEntries[mCount]=aStack->mEntries[theIndex];
      mEntries[mCount++].mParent=0;
    }
  }
} 
 

/**
 * 
 * @update  harishd 04/04/99
 * @update  gess 04/21/99
 */
nsIParserNode* nsEntryStack::Pop(void) {

  nsIParserNode* result=0;

  if(0<mCount) {
    result=mEntries[--mCount].mNode;

    ((nsCParserNode*)result)->mUseCount--;
    ((nsCParserNode*)result)->mToken->mUseCount--;
    mEntries[mCount].mNode=0;
    mEntries[mCount].mStyles=0;

    nsEntryStack* theStyleStack=mEntries[mCount].mParent;

    if(theStyleStack) {
      //now we have to tell the residual style stack where this tag
      //originated that it's no longer in use.
      PRUint32 scount=theStyleStack->mCount;
      PRUint32 sindex=0;

      nsTagEntry *theStyleEntry=theStyleStack->mEntries;
      for(sindex=scount-1;sindex>0;sindex--){            
        if(theStyleEntry->mTag==mEntries[mCount].mTag) {
          theStyleEntry->mParent=0;  //this tells us that the style is not open at any level
          break;
        }
        theStyleEntry++;
      } //for
    }
  }
  return result;
} 
 
/**
 * 
 * @update  harishd 04/04/99
 * @update  gess 04/21/99
 */
eHTMLTags nsEntryStack::First() const {
  eHTMLTags result=eHTMLTag_unknown;
  if(0<mCount){
    result=mEntries[0].mTag;
  }
  return result;
}

/**
 * 
 * @update  harishd 04/04/99
 * @update  gess 04/21/99
 */
nsIParserNode* nsEntryStack::NodeAt(PRInt32 anIndex) const {
  nsIParserNode* result=0;
  if((0<mCount) && (anIndex<mCount)) {
    result=mEntries[anIndex].mNode;
  }
  return result;
}

/**
 * 
 * @update  harishd 04/04/99
 * @update  gess 04/21/99
 */
eHTMLTags nsEntryStack::TagAt(PRInt32 anIndex) const {
  eHTMLTags result=eHTMLTag_unknown;
  if((0<mCount) && (anIndex<mCount)) {
    result=mEntries[anIndex].mTag;
  }
  return result;
}

/**
 * 
 * @update  gess 04/21/99
 */
nsTagEntry* nsEntryStack::EntryAt(PRInt32 anIndex) const {
  nsTagEntry *result=0;
  if((0<mCount) && (anIndex<mCount)) {
    result=&mEntries[anIndex];
  }
  return result;
}


/**
 * 
 * @update  harishd 04/04/99
 * @update  gess 04/21/99
 */
eHTMLTags nsEntryStack::operator[](PRInt32 anIndex) const {
  eHTMLTags result=eHTMLTag_unknown;
  if((0<mCount) && (anIndex<mCount)) {
    result=mEntries[anIndex].mTag;
  }
  return result;
}


/**
 * 
 * @update  harishd 04/04/99
 * @update  gess 04/21/99
 */
eHTMLTags nsEntryStack::Last() const {
  eHTMLTags result=eHTMLTag_unknown;
  if(0<mCount) {
    result=mEntries[mCount-1].mTag;
  }
  return result;
}

#if 0
/**
 * 
 * @update  harishd 04/04/99
 * @update  gess 04/21/99
 */
PRInt32 nsEntryStack::GetTopmostIndexOf(eHTMLTags aTag) const {
  int theIndex=0;
  for(theIndex=mCount-1;theIndex>0;theIndex--){
    if(aTag==TagAt(theIndex))
      return theIndex;
  }
  return kNotFound;

}
#endif


/***************************************************************
  Now define the dtdcontext class
 ***************************************************************/


/**
 * 
 * @update	gess9/10/98
 */
nsDTDContext::nsDTDContext() : mStack() {

  MOZ_COUNT_CTOR(nsDTDContext);
  mResidualStyleCount=0;
  mContextTopIndex=0;

#ifdef  NS_DEBUG
  memset(mXTags,0,sizeof(mXTags));
#endif
} 
 

/**
 * 
 * @update	gess9/10/98
 */
nsDTDContext::~nsDTDContext() {
  MOZ_COUNT_DTOR(nsDTDContext);
}

/**
 * 
 * @update  gess7/9/98
 */
PRBool nsDTDContext::HasOpenContainer(eHTMLTags aTag) const {
  PRInt32 theIndex=mStack.LastOf(aTag);
  return PRBool(-1<theIndex);
}

/**
 * 
 * @update  gess7/9/98
 */
void nsDTDContext::Push(const nsIParserNode* aNode,nsEntryStack* aStyleStack) {
  if(aNode) {

#ifdef  NS_DEBUG
    eHTMLTags theTag=(eHTMLTags)aNode->GetNodeType();
    int size=mStack.mCount;
    if(size< eMaxTags)
      mXTags[size]=theTag;
#endif
    mStack.Push((nsIParserNode*)aNode,aStyleStack);
  }
}

/** 
 * @update  gess 11/11/99, 
 *          harishd 04/04/99
 */
nsIParserNode* nsDTDContext::Pop(nsEntryStack *&aChildStyleStack) {

  PRInt32         theSize=mStack.mCount;
  nsIParserNode*  result=0;

  if(0<theSize) {

#ifdef  NS_DEBUG
    if ((theSize>0) && (theSize <= eMaxTags))
      mXTags[theSize-1]=eHTMLTag_unknown;
#endif


    nsTagEntry* theEntry=mStack.EntryAt(mStack.mCount-1);
    if(theEntry) {
      aChildStyleStack=theEntry->mStyles;
    }

    result=mStack.Pop();
    theEntry->mParent=0;
  }

  return result;
}


/**
 * 
 * @update  gess7/9/98
 */
eHTMLTags nsDTDContext::First(void) const {
  return mStack.First();
}

/**
 * 
 * @update  gess7/9/98
 */
eHTMLTags nsDTDContext::TagAt(PRInt32 anIndex) const {
  return mStack.TagAt(anIndex);
}


/**
 * 
 * @update  gess7/9/98
 */
nsTagEntry* nsDTDContext::LastEntry(void) const {
  return mStack.EntryAt(mStack.mCount-1);
}

/**
 *  
 * @update  gess7/9/98
 */
eHTMLTags nsDTDContext::Last() const {
  return mStack.Last();
}


/**
 * 
 * @update  gess7/9/98
 */
nsEntryStack* nsDTDContext::GetStylesAt(PRInt32 anIndex) const {
  nsEntryStack* result=0;

  if(anIndex<mStack.mCount){
    nsTagEntry* theEntry=mStack.EntryAt(anIndex);
    if(theEntry) {
      result=theEntry->mStyles;
    }
  }
  return result;
}


/**
 * 
 * @update  gess 04/28/99
 */
void nsDTDContext::PushStyle(const nsIParserNode* aNode){

  nsTagEntry* theEntry=mStack.EntryAt(mStack.mCount-1);
  if(theEntry ) {
    nsEntryStack* theStack=theEntry->mStyles;
    if(!theStack) {
      theStack=theEntry->mStyles=new nsEntryStack();
    }
    if(theStack) {
      theStack->Push(aNode);
      mResidualStyleCount++;
    }
  } //if
}


/**
 * Call this when you have an EntryStack full of styles
 * that you want to push at this level.
 * 
 * @update  gess 04/28/99
 */
void nsDTDContext::PushStyles(nsEntryStack *aStyles){

  if(aStyles) {
    nsTagEntry* theEntry=mStack.EntryAt(mStack.mCount-1);
    if(theEntry ) {
      nsEntryStack* theStyles=theEntry->mStyles;
      if(!theStyles) {
        theEntry->mStyles=aStyles;

        PRUint32 scount=aStyles->mCount;
        PRUint32 sindex=0;

        theEntry=aStyles->mEntries;
        for(sindex=0;sindex<scount;sindex++){            
          theEntry->mParent=0;  //this tells us that the style is not open at any level
          theEntry++;
          mResidualStyleCount++;
        } //for

      }
      else theStyles->Append(aStyles);
    } //if
  }//if
}


/** 
 * 
 * @update  gess 04/28/99
 */
nsIParserNode* nsDTDContext::PopStyle(void){
  nsIParserNode *result=0;

  nsTagEntry *theEntry=mStack.EntryAt(mStack.mCount-1);
  if(theEntry && (theEntry->mNode)) {
    nsEntryStack* theStyleStack=theEntry->mParent;
    if(theStyleStack){
      result=theStyleStack->Pop();
      mResidualStyleCount--;
    }
  } //if
  return result;
}

/** 
 * 
 * @update  gess 04/28/99
 */
nsIParserNode* nsDTDContext::PopStyle(eHTMLTags aTag){

  PRInt32 theLevel=0;

  for(theLevel=mStack.mCount-1;theLevel>0;theLevel--) {
    nsEntryStack *theStack=mStack.mEntries[theLevel].mStyles;
    if(theStack) {
      if(aTag==theStack->Last()) {
        return theStack->Pop();
        mResidualStyleCount--;
      } else {
        // NS_ERROR("bad residual style entry");
      }
    } 
  }

  return 0;
}

/**************************************************************
  Now define the tokenrecycler class...
 **************************************************************/

/**
 * 
 * @update  gess7/25/98
 * @param 
 */
CTokenRecycler::CTokenRecycler() : nsITokenRecycler(),mEmpty("") {

  MOZ_COUNT_CTOR(CTokenRecycler);

  int i=0;
  for(i=0;i<eToken_last-1;i++) {
    mTokenCache[i]=new nsDeque(0);
#ifdef NS_DEBUG
    mTotals[i]=0;
#endif
  }
}

/**
 * Destructor for the token factory
 * @update  gess7/25/98
 */
CTokenRecycler::~CTokenRecycler() {

  MOZ_COUNT_DTOR(CTokenRecycler);

  //begin by deleting all the known (recycled) tokens...
  //We're also deleting the cache-deques themselves.
  int i;

  CTokenDeallocator theDeallocator;
  for(i=0;i<eToken_last-1;i++) {
    if(0!=mTokenCache[i]) {
      mTokenCache[i]->ForEach(theDeallocator);
      delete mTokenCache[i];
      mTokenCache[i]=0;
    }
  }
}

class CTokenFinder: public nsDequeFunctor{
public:
  CTokenFinder(CToken* aToken) {mToken=aToken;}
  virtual void* operator()(void* anObject) {
    if(anObject==mToken) {
      return anObject;
    }
    return 0;
  }
  CToken* mToken;
};

/**
 * This method gets called when someone wants to recycle a token
 * @update  gess7/24/98
 * @param   aToken -- token to be recycled.
 * @return  nada
 */
void CTokenRecycler::RecycleToken(CToken* aToken) {
  if(aToken) {
    PRInt32 theType=aToken->GetTokenType();

#if 0
  //This should be disabled since it's only debug code.
    CTokenFinder finder(aToken);
    CToken* theMatch;
    theMatch=(CToken*)mTokenCache[theType-1]->FirstThat(finder);
    if(theMatch) {
      printf("dup token: %p\n",theMatch);
    }
#endif
    aToken->mUseCount=1;
    mTokenCache[theType-1]->Push(aToken);
  }
}


/**
 * 
 * @update	vidur 11/12/98
 * @param 
 * @return
 */
CToken* CTokenRecycler::CreateTokenOfType(eHTMLTokenTypes aType,eHTMLTags aTag, const nsString& aString) {

  CToken* result=(CToken*)mTokenCache[aType-1]->Pop();

  if(result) {
    result->Reinitialize(aTag,aString);
  }
  else {
#ifdef  NS_DEBUG
    mTotals[aType-1]++;
#endif
    switch(aType){
      case eToken_start:            result=new CStartToken(aTag); break;
      case eToken_end:              result=new CEndToken(aTag); break;
      case eToken_comment:          result=new CCommentToken(); break;
      case eToken_entity:           result=new CEntityToken(aString); break;
      case eToken_whitespace:       result=new CWhitespaceToken(); break;
      case eToken_newline:          result=new CNewlineToken(); break;
      case eToken_text:             result=new CTextToken(aString); break;
      case eToken_attribute:        result=new CAttributeToken(); break;
      case eToken_script:           result=new CScriptToken(); break;
      case eToken_style:            result=new CStyleToken(); break;
      case eToken_skippedcontent:   result=new CSkippedContentToken(aString); break;
      case eToken_instruction:      result=new CInstructionToken(); break;
      case eToken_cdatasection:     result=new CCDATASectionToken(); break;
      case eToken_error:            result=new CErrorToken(); break;
      case eToken_doctypeDecl:      result=new CDoctypeDeclToken(); break;
        default:
          break;
    }
  }
  return result;
}

/**
 * 
 * @update	vidur 11/12/98
 * @param 
 * @return
 */
CToken* CTokenRecycler::CreateTokenOfType(eHTMLTokenTypes aType,eHTMLTags aTag) {

  CToken* result=(CToken*)mTokenCache[aType-1]->Pop();

  if(result) {
    result->Reinitialize(aTag,mEmpty);
  }
  else {
#ifdef  NS_DEBUG
    mTotals[aType-1]++;
#endif
    switch(aType){
      case eToken_start:            result=new CStartToken(aTag); break;
      case eToken_end:              result=new CEndToken(aTag); break;
      case eToken_comment:          result=new CCommentToken(); break;
      case eToken_attribute:        result=new CAttributeToken(); break;
      case eToken_entity:           result=new CEntityToken(); break;
      case eToken_whitespace:       result=new CWhitespaceToken(); break;
      case eToken_newline:          result=new CNewlineToken(); break;
      case eToken_text:             result=new CTextToken(mEmpty); break;
      case eToken_script:           result=new CScriptToken(); break;
      case eToken_style:            result=new CStyleToken(); break;
      case eToken_skippedcontent:   result=new CSkippedContentToken(mEmpty); break;
      case eToken_instruction:      result=new CInstructionToken(); break;
      case eToken_cdatasection:     result=new CCDATASectionToken(); break;
      case eToken_error:            result=new CErrorToken(); break;
      case eToken_doctypeDecl:      result=new CDoctypeDeclToken(aTag); break;
        default:
          break;
    }
  }
  return result;
}

void DebugDumpContainmentRules(nsIDTD& theDTD,const char* aFilename,const char* aTitle) {
#ifdef RICKG_DEBUG

#include <fstream.h>

  const char* prefix="     ";
  fstream out(aFilename,ios::out);
  out << "==================================================" << endl;
  out << aTitle << endl;
  out << "==================================================";
  int i,j=0;
  int written;
  for(i=1;i<eHTMLTag_text;i++){
    const char* tag=nsHTMLTags::GetStringValue((eHTMLTags)i);
    out << endl << endl << "Tag: <" << tag << ">" << endl;
    out << prefix;
    written=0;
    if(theDTD.IsContainer(i)) {
      for(j=1;j<eHTMLTag_text;j++){
        if(15==written) {
          out << endl << prefix;
          written=0;
        }
        if(theDTD.CanContain(i,j)){
          tag=nsHTMLTags::GetStringValue((eHTMLTags)j);
          if(tag) {
            out<< tag << ", ";
            written++;
          }
        }
      }//for
    }
    else out<<"(not container)" << endl;
  }
#endif
}


/*************************************************************************
 *  The table lookup technique was adapted from the algorithm described  *
 *  by Avram Perez, Byte-wise CRC Calculations, IEEE Micro 3, 40 (1983). *
 *************************************************************************/

#define POLYNOMIAL 0x04c11db7L

static PRBool crc_table_initialized;
static PRUint32 crc_table[256];

static void gen_crc_table() {
 /* generate the table of CRC remainders for all possible bytes */
  int i, j;  
  PRUint32 crc_accum;
  for ( i = 0;  i < 256;  i++ ) { 
    crc_accum = ( (unsigned long) i << 24 );
    for ( j = 0;  j < 8;  j++ ) { 
      if ( crc_accum & 0x80000000L )
        crc_accum = ( crc_accum << 1 ) ^ POLYNOMIAL;
      else crc_accum = ( crc_accum << 1 ); 
    }
    crc_table[i] = crc_accum; 
  }
  return; 
}

PRUint32 AccumulateCRC(PRUint32 crc_accum, char *data_blk_ptr, int data_blk_size)  {
  if (!crc_table_initialized) {
    gen_crc_table();
    crc_table_initialized = PR_TRUE;
  }

 /* update the CRC on the data block one byte at a time */
  int i, j;
  for ( j = 0;  j < data_blk_size;  j++ ) { 
    i = ( (int) ( crc_accum >> 24) ^ *data_blk_ptr++ ) & 0xff;
    crc_accum = ( crc_accum << 8 ) ^ crc_table[i]; 
  }
  return crc_accum; 
}

/******************************************************************************
  This class is used to store ref's to tag observers during the parse phase.
  Note that for simplicity, this is a singleton that is constructed in the
  CNavDTD and shared for the duration of the application session. Later on it
  might be nice to use a more dynamic approach that would permit observers to
  come and go on a document basis.
 ******************************************************************************/

CObserverService::CObserverService() {

  MOZ_COUNT_CTOR(CObserverService);

  nsCRT::zero(mObservers,sizeof(mObservers));

  nsAutoString theHTMLTopic("htmlparser");
  RegisterObservers(theHTMLTopic);

  nsAutoString theXMLTopic("xmlparser");
  RegisterObservers(theXMLTopic);

}

CObserverService::~CObserverService() {

  MOZ_COUNT_DTOR(CObserverService);

  UnregisterObservers();
}

/**************************************************************
  Define the nsIElementObserver release class...
 **************************************************************/
class nsObserverReleaser: public nsDequeFunctor{
public:
  virtual void* operator()(void* anObject) {
    nsIElementObserver* theObserver= (nsIElementObserver*)anObject;
    NS_RELEASE(theObserver);
    return 0;
  }
};

/**
 * Release observers and empty the observer array.
 * 
 * @update harishd 08/29/99
 * @param  
 * @return 
 */

void CObserverService::UnregisterObservers() {
  int theIndex=0;
  nsObserverReleaser theReleaser;
  for(theIndex=0;theIndex<=NS_HTML_TAG_MAX;theIndex++){
    if(mObservers[theIndex]){
      mObservers[theIndex]->ForEach(theReleaser);
      delete mObservers[theIndex];
    }
  }
}

/**
 * This method will maintain lists of observers registered for specific tags.
 * 
 * @update harishd 08/29/99
 * @param  aTopic  -  The topic under which observers register for.
 * @return if SUCCESS return NS_OK else return ERROR code.
 */

void CObserverService::RegisterObservers(nsString& aTopic) {
  nsresult result = NS_OK;
  nsIObserverService* theObserverService = nsnull;
  result = nsServiceManager::GetService(NS_OBSERVERSERVICE_PROGID, NS_GET_IID(nsIObserverService),
                                      (nsISupports**) &theObserverService, nsnull);
  if(result == NS_OK){
    nsIEnumerator* theEnum = nsnull;
    result = theObserverService->EnumerateObserverList(aTopic.GetUnicode(), &theEnum);
    nsServiceManager::ReleaseService(NS_OBSERVERSERVICE_PROGID, theObserverService);
    if(result == NS_OK) {
      nsIElementObserver *theElementObserver = nsnull;
      nsISupports *inst = nsnull;
      
      for (theEnum->First(); theEnum->IsDone() != NS_OK; theEnum->Next()) {
        result = theEnum->CurrentItem(&inst);
        if (NS_SUCCEEDED(result)) {
          result = inst->QueryInterface(NS_GET_IID(nsIElementObserver), (void**)&theElementObserver);
          NS_RELEASE(inst);
        }
        if (result == NS_OK) {
          const char* theTagStr = nsnull;
          PRUint32 theTagIndex = 0;
          theTagStr = theElementObserver->GetTagNameAt(theTagIndex);
          while (theTagStr != nsnull) {
            eHTMLTags theTag = nsHTMLTags::LookupTag(nsCAutoString(theTagStr));
            if((eHTMLTag_userdefined!=theTag) && (theTag <= NS_HTML_TAG_MAX)){
              if(mObservers[theTag] == nsnull) {
                 mObservers[theTag] = new nsDeque(0);
              }
              mObservers[theTag]->Push(theElementObserver);
            }
            theTagIndex++;
            theTagStr = theElementObserver->GetTagNameAt(theTagIndex);
          }
        }
      }
    }
    NS_IF_RELEASE(theEnum);
  }
}

/**
 * This method will notify observers registered for specific tags.
 * 
 * @update harishd 08/29/99
 * @param  aTag            -  The tag for which observers could be waiting for.
 * @param  aNode           -  
 * @param  aUniqueID       -  The document ID.
 * @param  aDTD            -  The current DTD.
 * @param  aCharsetValue   -
 * @param  aCharsetSource  -
 * @return if SUCCESS return NS_OK else return ERROR code.
 */
nsresult CObserverService::Notify(eHTMLTags aTag,nsIParserNode& aNode,PRUint32 aUniqueID, const char* aCommand,
                                  nsIParser* aParser) {
  nsresult  result=NS_OK;
  nsDeque*  theDeque=GetObserversForTag(aTag);
  if(theDeque){ 

    nsAutoString      theCharsetValue;
    nsCharsetSource   theCharsetSource;
    aParser->GetDocumentCharset(theCharsetValue,theCharsetSource);

    PRInt32 theAttrCount =aNode.GetAttributeCount(); 
    PRUint32 theDequeSize=theDeque->GetSize(); 
    if(0<theDequeSize){
      PRInt32 index = 0; 
      const PRUnichar* theKeys[50]  = {0,0,0,0,0}; // XXX -  should be dynamic
      const PRUnichar* theValues[50]= {0,0,0,0,0}; // XXX -  should be dynamic
      for(index=0; index<theAttrCount && index < 50; index++) {
        theKeys[index]   = aNode.GetKeyAt(index).GetUnicode(); 
        theValues[index] = aNode.GetValueAt(index).GetUnicode(); 
      } 
      nsAutoString theCharsetKey("charset"); 
      nsAutoString theSourceKey("charsetSource"); 
      nsAutoString intValue;
      
      // Add pseudo attribute in the end

      if(index>=47) index=47;  //XXX HACK HACK HACK!!!!! 
                               //We really need to do a better job with attributes here.


      if(index < 50) {
        theKeys[index]=theCharsetKey.GetUnicode(); 
        theValues[index] = theCharsetValue.GetUnicode();
        index++;
      }
      if(index < 50) {
        theKeys[index]=theSourceKey.GetUnicode(); 
        PRInt32 sourceInt = theCharsetSource;
        intValue.Append(sourceInt,10);
        theValues[index] = intValue.GetUnicode();
	  	  index++;
      }
      nsAutoString theDTDKey("X_COMMAND");
      nsAutoString theDTDValue(aCommand);
      if(index < 50) {
        theKeys[index]=theDTDKey.GetUnicode();
        theValues[index]=theDTDValue.GetUnicode();
        index++;
      }
      nsAutoString theTagStr(nsHTMLTags::GetStringValue(aTag));
      nsObserverNotifier theNotifier(theTagStr.GetUnicode(),aUniqueID,index,theKeys,theValues);
      theDeque->FirstThat(theNotifier); 
      result=theNotifier.mResult; 
     }//if 
  } 
  return result;
}

/**
 * This method will look for the list of observers registered for 
 * a specific tag.
 * 
 * @update harishd 08/29/99
 * @param aTag - The tag for which observers could be waiting for.
 * @return if FOUND return "observer list" else return nsnull;
 *
 */

nsDeque* CObserverService::GetObserversForTag(eHTMLTags aTag) {
  if(aTag <= NS_HTML_TAG_MAX)
      return mObservers[aTag];
  return nsnull;
}