src/util/StringPool.cpp

/*
 * The Apache Software License, Version 1.1
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 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
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 * This software consists of voluntary contributions made by many
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/**
 * $Log$
 * Revision 1.1  1999/11/09 01:05:10  twl
 * Initial revision
 *
 * Revision 1.2  1999/11/08 20:45:14  rahul
 * Swat for adding in Product name and CVS comment log variable.
 *
 */


// ---------------------------------------------------------------------------
//  Includes
// ---------------------------------------------------------------------------
#include <util/IllegalArgumentException.hpp>
#include <util/StringPool.hpp>
#include <util/XMLExceptMsgs.hpp>
#include <util/XMLString.hpp>
#include <memory.h>


// ---------------------------------------------------------------------------
//  StringPool::PoolElem: Constructors and Destructor
// ---------------------------------------------------------------------------
XMLStringPool::PoolElem::PoolElem(  const   XMLCh* const string
                                    , const unsigned int id) :
    fId(id)
    , fString(0)
{
    fString = XMLString::replicate(string);
}

XMLStringPool::PoolElem::~PoolElem()
{
    delete [] fString;
}

// ---------------------------------------------------------------------------
//  StringPool::PoolElem: Public methods
// ---------------------------------------------------------------------------
const XMLCh* XMLStringPool::PoolElem::getKey() const
{
    return fString;
}

void
XMLStringPool::PoolElem::reset(const XMLCh* const string, const unsigned int id)
{
    fId = id;
    delete [] fString;
    fString = XMLString::replicate(string);
}



// ---------------------------------------------------------------------------
//  XMLStringPool: Constructors and Destructor
// ---------------------------------------------------------------------------
XMLStringPool::XMLStringPool(const  unsigned int  modulus) :

    fIdMap(0)
    , fHashTable(0)
    , fMapCapacity(64)
    , fCurId(1)
{
    // Create the hash table, passing it the modulus
    fHashTable = new RefHashTableOf<PoolElem>(modulus);

    // Do an initial allocation of the id map and zero it all out
    fIdMap = new PoolElem*[fMapCapacity];
    memset(fIdMap, 0, sizeof(PoolElem*) * fMapCapacity);
}

XMLStringPool::~XMLStringPool()
{
    delete fHashTable;
    delete [] fIdMap;
}


// ---------------------------------------------------------------------------
//  XMLStringPool: Pool management methods
// ---------------------------------------------------------------------------
unsigned int XMLStringPool::addOrFind(const XMLCh* const newString)
{
    PoolElem* elemToFind = fHashTable->get(newString);
    if (elemToFind)
        return elemToFind->fId;

    return addNewEntry(newString);
}


bool XMLStringPool::exists(const XMLCh* const newString) const
{
    return fHashTable->containsKey(newString);
}

void XMLStringPool::flushAll()
{
    fCurId = 1;
    fHashTable->removeAll();
}


unsigned int XMLStringPool::getId(const XMLCh* const toFind) const
{
    PoolElem* elemToFind = fHashTable->get(toFind);
    if (elemToFind)
        return elemToFind->fId;

    // Not found, so return zero, which is never a legal id
    return 0;    
}


const XMLCh* XMLStringPool::getValueForId(const unsigned int id) const
{
    if (!id || (id >= fCurId))
        ThrowXML(IllegalArgumentException, XML4CExcepts::StrPool_IllegalId);

    // Just index the id map and return that element's string
    return fIdMap[id]->fString;
}


// ---------------------------------------------------------------------------
//  XMLStringPool: Private helper methods
// ---------------------------------------------------------------------------
unsigned int XMLStringPool::addNewEntry(const XMLCh* const newString)
{
    // See if we need to expand the id map
    if (fCurId == fMapCapacity)
    {
        // Calculate the new capacity, create a temp new map, and zero it
        const unsigned int newCap = (unsigned int)(fMapCapacity * 1.5);
        PoolElem** newMap = new PoolElem*[newCap];
        memset(newMap, 0, sizeof(PoolElem*) * newCap);

        //
        //  Copy over the old elements from the old map. They are just pointers
        //  so we can do it all at once.
        //
        memcpy(newMap, fIdMap, sizeof(PoolElem*) * fMapCapacity);

        // Clean up the old map and store the new info
        delete [] fIdMap;
        fIdMap = newMap;
        fMapCapacity = newCap;
    }

    //
    //  Ok, now create a new element and add it to the hash table. Then store
    //  this new element in the id map at the current id index, then bump the
    //  id index.
    //
    PoolElem* newElem = new PoolElem(newString, fCurId);
    fHashTable->put(newElem);
    fIdMap[fCurId] = newElem;

    // Bump the current id and return the id of the new elem we just added
    fCurId++;
    return newElem->fId;
}