envrnmnt.c

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   /*******************************************************/
   /*      "C" Language Integrated Production System      */
   /*                                                     */
   /*             CLIPS Version 6.30  10/19/06            */
   /*                                                     */
   /*                ENVIRONMENT MODULE                   */
   /*******************************************************/

/*************************************************************/
/* Purpose: Routines for supporting multiple environments.   */
/*                                                           */
/* Principal Programmer(s):                                  */
/*      Gary D. Riley                                        */
/*                                                           */
/* Revision History:                                         */
/*                                                           */
/*      6.24: Added code to CreateEnvironment to free        */
/*            already allocated data if one of the malloc    */
/*            calls fail.                                    */
/*                                                           */
/*            Modified AllocateEnvironmentData to print a    */
/*            message if it was unable to allocate memory.   */
/*                                                           */
/*            Renamed BOOLEAN macro type to intBool.         */
/*                                                           */
/*            Added CreateRuntimeEnvironment function.       */
/*                                                           */
/*            Added support for context information when an  */
/*            environment is created (i.e a pointer from the */
/*            CLIPS environment to its parent environment).  */
/*                                                           */
/*      6.30: Added support for passing context information  */ 
/*            to user defined functions.                     */
/*                                                           */
/*************************************************************/

#define _ENVRNMNT_SOURCE_

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "setup.h"

#include "memalloc.h"
#include "prntutil.h"
#include "router.h"
#include "engine.h"
#include "sysdep.h"
#include "utility.h"

#include "envrnmnt.h"

#define SIZE_ENVIRONMENT_HASH  131

/***************************************/
/* LOCAL INTERNAL FUNCTION DEFINITIONS */
/***************************************/

#if ALLOW_ENVIRONMENT_GLOBALS
   static void                    AddHashedEnvironment(struct environmentData *);
   static struct environmentData *FindEnvironment(unsigned long);
   static intBool                 RemoveHashedEnvironment(struct environmentData *);
   static void                    InitializeEnvironmentHashTable(void);
#endif
   static void                    RemoveEnvironmentCleanupFunctions(struct environmentData *);
   static void                   *CreateEnvironmentDriver(struct symbolHashNode **,struct floatHashNode **,
                                                          struct integerHashNode **,struct bitMapHashNode **);

/***************************************/
/* LOCAL INTERNAL VARIABLE DEFINITIONS */
/***************************************/

#if ALLOW_ENVIRONMENT_GLOBALS
   static unsigned long              NextEnvironmentIndex = 0;
   static struct environmentData   **EnvironmentHashTable = NULL;
   static struct environmentData    *CurrentEnvironment = NULL;
#endif

/*******************************************************/
/* AllocateEnvironmentData: Allocates environment data */
/*    for the specified environment data record.       */
/*******************************************************/
globle intBool AllocateEnvironmentData(
  void *vtheEnvironment,
  unsigned int position,
  unsigned long size,
  void (*cleanupFunction)(void *))
  {      
   struct environmentData *theEnvironment = (struct environmentData *) vtheEnvironment;

   /*===========================================*/
   /* Environment data can't be of length zero. */
   /*===========================================*/
   
   if (size <= 0)
     {
      printf("\n[ENVRNMNT1] Environment data position %d allocated with size of 0 or less.\n",position);      
      return(FALSE);
     }
     
   /*================================================================*/
   /* Check to see if the data position exceeds the maximum allowed. */
   /*================================================================*/
   
   if (position >= MAXIMUM_ENVIRONMENT_POSITIONS)
     {
      printf("\n[ENVRNMNT2] Environment data position %d exceeds the maximum allowed.\n",position);      
      return(FALSE);
     }
     
   /*============================================================*/
   /* Check if the environment data has already been registered. */
   /*============================================================*/
   
   if (theEnvironment->theData[position] != NULL)
     {
      printf("\n[ENVRNMNT3] Environment data position %d already allocated.\n",position);      
      return(FALSE);
     }
     
   /*====================*/
   /* Allocate the data. */
   /*====================*/
   
   theEnvironment->theData[position] = malloc(size);
   if (theEnvironment->theData[position] == NULL)
     {
      printf("\n[ENVRNMNT4] Environment data position %d could not be allocated.\n",position);      
      return(FALSE);
     }
   
   memset(theEnvironment->theData[position],0,size);
   
   /*=============================*/
   /* Store the cleanup function. */
   /*=============================*/
   
   theEnvironment->cleanupFunctions[position] = cleanupFunction;
   
   /*===============================*/
   /* Data successfully registered. */
   /*===============================*/
   
   return(TRUE);
  }

/***************************************************************/
/* DeallocateEnvironmentData: Deallocates all environments     */
/*   stored in the environment hash table and then deallocates */
/*   the environment hash table.                               */
/***************************************************************/
globle intBool DeallocateEnvironmentData()
  {
#if ALLOW_ENVIRONMENT_GLOBALS
   struct environmentData *theEnvironment, *nextEnvironment;
   int i, rv = TRUE;
   
   for (i = 0; i < SIZE_ENVIRONMENT_HASH; i++)
     {
      for (theEnvironment = EnvironmentHashTable[i];
           theEnvironment != NULL;
          )
        {
         nextEnvironment = theEnvironment->next;
         
         if (! DestroyEnvironment(theEnvironment))
           { rv = FALSE; }
         
         theEnvironment = nextEnvironment;
        }
     }

   free(EnvironmentHashTable);
   
   return(rv);
#else
   return(FALSE);
#endif
  }

#if ALLOW_ENVIRONMENT_GLOBALS
/*********************************************************/
/* InitializeEnvironmentHashTable: Initializes the table */
/*   entries in the environment hash table to NULL.      */
/*********************************************************/
static void InitializeEnvironmentHashTable()
  {
   int i;
    
   if (EnvironmentHashTable != NULL)
     { return; }

   EnvironmentHashTable = (struct environmentData **)
                          malloc(sizeof (struct environmentData *) * SIZE_ENVIRONMENT_HASH);

   if (EnvironmentHashTable == NULL)
     {
      printf("\n[ENVRNMNT4] Unable to initialize environment hash table.\n");      
      return;
     }

   for (i = 0; i < SIZE_ENVIRONMENT_HASH; i++) EnvironmentHashTable[i] = NULL;
  }

/*********************************************/
/* AddHashedEnvironment: Adds an environment */
/*    entry to the environment hash table.   */
/*********************************************/
static void AddHashedEnvironment(
  struct environmentData *theEnvironment)
  {
   struct environmentData *temp;
   unsigned long hashValue;
   
   if (EnvironmentHashTable == NULL)
     { InitializeEnvironmentHashTable(); }
     
   hashValue = theEnvironment->environmentIndex % SIZE_ENVIRONMENT_HASH;

   temp = EnvironmentHashTable[hashValue];
   EnvironmentHashTable[hashValue] = theEnvironment;
   theEnvironment->next = temp;
  }
  
/***************************************************/
/* RemoveHashedEnvironment: Removes an environment */
/*   entry from the environment hash table.        */
/***************************************************/
static intBool RemoveHashedEnvironment(
  struct environmentData *theEnvironment)
  {
   unsigned long hashValue;
   struct environmentData *hptr, *prev;

   hashValue = theEnvironment->environmentIndex % SIZE_ENVIRONMENT_HASH;

   for (hptr = EnvironmentHashTable[hashValue], prev = NULL;
        hptr != NULL;
        hptr = hptr->next)
     {
      if (hptr == theEnvironment)
        {
         if (prev == NULL)
           {
            EnvironmentHashTable[hashValue] = hptr->next;
            return(TRUE);
           }
         else
           {
            prev->next = hptr->next;
            return(TRUE);
           }
        }
      prev = hptr;
     }

   return(FALSE);
  }

/**********************************************************/
/* FindEnvironment: Determines if a specified environment */
/*   index has an entry in the environment hash table.    */
/**********************************************************/
static struct environmentData *FindEnvironment(
  unsigned long environmentIndex)
  {
   struct environmentData *theEnvironment;
   unsigned long hashValue;
   
   hashValue = environmentIndex % SIZE_ENVIRONMENT_HASH;
   
   for (theEnvironment = EnvironmentHashTable[hashValue];
        theEnvironment != NULL;
        theEnvironment = theEnvironment->next)
     {
      if (theEnvironment->environmentIndex == environmentIndex)
        { return(theEnvironment); }
     }

   return(NULL);
  }
#endif

/************************************************************/
/* CreateEnvironment: Creates an environment data structure */
/*   and initializes its content to zero/null.              */
/************************************************************/
globle void *CreateEnvironment()
  {
   return CreateEnvironmentDriver(NULL,NULL,NULL,NULL);
  }

/**********************************************************/
/* CreateRuntimeEnvironment: Creates an environment data  */
/*   structure and initializes its content to zero/null.  */
/**********************************************************/
globle void *CreateRuntimeEnvironment(
  struct symbolHashNode **symbolTable,
  struct floatHashNode **floatTable,
  struct integerHashNode **integerTable,
  struct bitMapHashNode **bitmapTable)
  {
   return CreateEnvironmentDriver(symbolTable,floatTable,integerTable,bitmapTable);
  }
  
/*********************************************************/
/* CreateEnvironmentDriver: Creates an environment data  */
/*   structure and initializes its content to zero/null. */
/*********************************************************/
globle void *CreateEnvironmentDriver(
  struct symbolHashNode **symbolTable,
  struct floatHashNode **floatTable,
  struct integerHashNode **integerTable,
  struct bitMapHashNode **bitmapTable)
  {
   struct environmentData *theEnvironment;
   void *theData;
   
   theEnvironment = (struct environmentData *) malloc(sizeof(struct environmentData));
  
   if (theEnvironment == NULL)
     {
      printf("\n[ENVRNMNT5] Unable to create new environment.\n");
      return(NULL);
     }

   theData = malloc(sizeof(void *) * MAXIMUM_ENVIRONMENT_POSITIONS);
   
   if (theData == NULL)
     {
      free(theEnvironment);
      printf("\n[ENVRNMNT6] Unable to create environment data.\n");
      return(NULL);
     }