Torque2D/engine/source/string/stringTable.cc

//-----------------------------------------------------------------------------
// Copyright (c) 2013 GarageGames, LLC
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
//-----------------------------------------------------------------------------

#include "platform/platform.h"
#include "stringTable.h"

_StringTable *StringTable = NULL;
const U32 _StringTable::csm_stInitSize = 29;
StringTableEntry _StringTable::EmptyString;

//---------------------------------------------------------------
//
// StringTable functions
//
//---------------------------------------------------------------

namespace {
bool sgInitTable = true;
U8   sgHashTable[256];

void initTolowerTable()
{
   for (U32 i = 0; i < 256; i++) {
      U8 c = dTolower(i);
      sgHashTable[i] = c * c;
   }

   sgInitTable = false;
}

} // namespace {}

U32 _StringTable::hashString(const char* str)
{
   if (sgInitTable)
      initTolowerTable();

   U32 ret = 0;
   char c;
   while((c = *str++) != 0) {
      ret <<= 1;
      ret ^= sgHashTable[c];
   }
   return ret;
}

U32 _StringTable::hashStringn(const char* str, S32 len)
{
   if (sgInitTable)
      initTolowerTable();

   U32 ret = 0;
   char c;
   while((c = *str++) != 0 && len--) {
      ret <<= 1;
      ret ^= sgHashTable[c];
   }
   return ret;
}

//--------------------------------------
_StringTable::_StringTable()
{
   buckets = (Node **) dMalloc(csm_stInitSize * sizeof(Node *));
   for(U32 i = 0; i < csm_stInitSize; i++) {
      buckets[i] = 0;
   }

   numBuckets = csm_stInitSize;
   itemCount = 0;

   // Insert empty string.
   EmptyString = insert("");
}

//--------------------------------------
_StringTable::~_StringTable()
{
   dFree(buckets);
}


//--------------------------------------
void _StringTable::create()
{
   AssertFatal(StringTable == NULL, "StringTable::create: StringTable already exists.");
   StringTable = new _StringTable;
}


//--------------------------------------
void _StringTable::destroy()
{
   AssertFatal(StringTable != NULL, "StringTable::destroy: StringTable does not exist.");
   delete StringTable;
   StringTable = NULL;
}

//--------------------------------------
StringTableEntry _StringTable::insert(const char* val, const bool  caseSens)
{
   if ( val == NULL )
       return StringTable->EmptyString;

   MutexHandle mutex;
   mutex.lock(&mMutex, true);

   Node **walk, *temp;
   U32 key = hashString(val);
   walk = &buckets[key % numBuckets];
   while((temp = *walk) != NULL)   {
      if(caseSens && !dStrcmp(temp->val, val))
         return temp->val;
      else if(!caseSens && !dStricmp(temp->val, val))
         return temp->val;
      walk = &(temp->next);
   }
   char *ret = 0;
   if(!*walk) {
      *walk = (Node *) mempool.alloc(sizeof(Node));
      (*walk)->next = 0;
      (*walk)->val = (char *) mempool.alloc(dStrlen(val) + 1);
      dStrcpy((*walk)->val, val);
      ret = (*walk)->val;
      itemCount ++;
   }
   if(itemCount > 2 * numBuckets) {
      resize(4 * numBuckets - 1);
   }
   return ret;
}

//--------------------------------------
StringTableEntry _StringTable::insertn(const char* src, S32 len, const bool  caseSens)
{
   if ( src == NULL )
       return StringTable->EmptyString;

   MutexHandle mutex;
   mutex.lock(&mMutex, true);

   char val[1024];
   AssertFatal(len < sizeof(val), "Invalid string to insertn");
   dStrncpy(val, src, len);
   val[len] = 0;
   return insert(val, caseSens);
}

//--------------------------------------
StringTableEntry _StringTable::lookup(const char* val, const bool  caseSens)
{
   if ( val == NULL )
       return StringTable->EmptyString;

   MutexHandle mutex;
   mutex.lock(&mMutex, true);

   Node **walk, *temp;
   U32 key = hashString(val);
   walk = &buckets[key % numBuckets];
   while((temp = *walk) != NULL)   {
      if(caseSens && !dStrcmp(temp->val, val))
            return temp->val;
      else if(!caseSens && !dStricmp(temp->val, val))
         return temp->val;
      walk = &(temp->next);
   }
   return NULL;
}

//--------------------------------------
StringTableEntry _StringTable::lookupn(const char* val, S32 len, const bool  caseSens)
{
   if ( val == NULL )
       return StringTable->EmptyString;

   Node **walk, *temp;
   U32 key = hashStringn(val, len);
   walk = &buckets[key % numBuckets];
   while((temp = *walk) != NULL) {
      if(caseSens && !dStrncmp(temp->val, val, len) && temp->val[len] == 0)
         return temp->val;
      else if(!caseSens && !dStrnicmp(temp->val, val, len) && temp->val[len] == 0)
         return temp->val;
      walk = &(temp->next);
   }
   return NULL;
}

//--------------------------------------
void _StringTable::resize(const U32 newSize)
{
   Node *head = NULL, *walk, *temp;
   U32 i;
   // reverse individual bucket lists
   // we do this because new strings are added at the end of bucket
   // lists so that case sens strings are always after their
   // corresponding case insens strings

   for(i = 0; i < numBuckets; i++) {
      walk = buckets[i];
      while(walk)
      {
         temp = walk->next;
         walk->next = head;
         head = walk;
         walk = temp;
      }
   }
   buckets = (Node **) dRealloc(buckets, newSize * sizeof(Node));
   for(i = 0; i < newSize; i++) {
      buckets[i] = 0;
   }
   numBuckets = newSize;
   walk = head;
   while(walk) {
      U32 key;
      Node *temp = walk;

      walk = walk->next;
      key = hashString(temp->val);
      temp->next = buckets[key % newSize];
      buckets[key % newSize] = temp;
   }
}