swig/Lib/ruby/rubytracking.swg

/***********************************************************************
 * rubytracking.swg
 *
 * This file contains support for tracking mappings from 
 * Ruby objects to C++ objects.  This functionality is needed
 * to implement mark functions for Ruby's mark and sweep
 * garbage collector.
 ************************************************************************/


#ifdef __cplusplus
extern "C" {
#endif


/* Global Ruby hash table to store Trackings from C/C++
   structs to Ruby Objects. */
static VALUE swig_ruby_trackings;

/* Global variable that stores a reference to the ruby
   hash table delete function. */
static ID swig_ruby_hash_delete = 0;

/* Setup a Ruby hash table to store Trackings */
SWIGRUNTIME void SWIG_RubyInitializeTrackings(void) {
  /* Create a ruby hash table to store Trackings from C++ 
     objects to Ruby objects.  Also make sure to tell
     the garabage collector about the hash table. */
  swig_ruby_trackings = rb_hash_new();
  rb_gc_register_address(&swig_ruby_trackings);
  
  /* Now store a reference to the hash table delete function
     so that we only have to look it up once.*/
  swig_ruby_hash_delete = rb_intern("delete");
}

/* Get a Ruby number to reference a pointer */
SWIGRUNTIME VALUE SWIG_RubyPtrToReference(void* ptr) {
  /* We cast the pointer to an unsigned long
     and then store a reference to it using
     a Ruby number object. */

  /* Convert the pointer to a Ruby number */
  unsigned long value = (unsigned long) ptr;
  return LONG2NUM(value);
}

/* Get a Ruby number to reference an object */
SWIGRUNTIME VALUE SWIG_RubyObjectToReference(VALUE object) {
  /* We cast the object to an unsigned long
     and then store a reference to it using
     a Ruby number object. */

  /* Convert the Object to a Ruby number */
  unsigned long value = (unsigned long) object;
  return LONG2NUM(value);
}

/* Get a Ruby object from a previously stored reference */
SWIGRUNTIME VALUE SWIG_RubyReferenceToObject(VALUE reference) {
  /* The provided Ruby number object is a reference
     to the Ruby object we want.*/

  /* First convert the Ruby number to a C number */
  unsigned long value = NUM2LONG(reference);
  return (VALUE) value;
}

/* Add a Tracking from a C/C++ struct to a Ruby object */
SWIGRUNTIME void SWIG_RubyAddTracking(void* ptr, VALUE object) {
  /* In a Ruby hash table we store the pointer and
     the associated Ruby object.  The trick here is
     that we cannot store the Ruby object directly - if
     we do then it cannot be garbage collected.  So
     instead we typecast it as a unsigned long and
     convert it to a Ruby number object.*/

  /* Get a reference to the pointer as a Ruby number */
  VALUE key = SWIG_RubyPtrToReference(ptr);

  /* Get a reference to the Ruby object as a Ruby number */
  VALUE value = SWIG_RubyObjectToReference(object);

  /* Store the mapping to the global hash table. */
  rb_hash_aset(swig_ruby_trackings, key, value);
}

/* Get the Ruby object that owns the specified C/C++ struct */
SWIGRUNTIME VALUE SWIG_RubyInstanceFor(void* ptr) {
  /* Get a reference to the pointer as a Ruby number */
  VALUE key = SWIG_RubyPtrToReference(ptr);

  /* Now lookup the value stored in the global hash table */
  VALUE value = rb_hash_aref(swig_ruby_trackings, key);
	
  if (value == Qnil) {
    /* No object exists - return nil. */
    return Qnil;
  }
  else {
    /* Convert this value to Ruby object */
    return SWIG_RubyReferenceToObject(value);
  }
}

/* Remove a Tracking from a C/C++ struct to a Ruby object.  It
   is very important to remove objects once they are destroyed
   since the same memory address may be reused later to create
   a new object. */
SWIGRUNTIME void SWIG_RubyRemoveTracking(void* ptr) {
  /* Get a reference to the pointer as a Ruby number */
  VALUE key = SWIG_RubyPtrToReference(ptr);

  /* Delete the object from the hash table by calling Ruby's
     do this we need to call the Hash.delete method.*/
  rb_funcall(swig_ruby_trackings, swig_ruby_hash_delete, 1, key);
}

/* This is a helper method that unlinks a Ruby object from its
   underlying C++ object.  This is needed if the lifetime of the
   Ruby object is longer than the C++ object */
SWIGRUNTIME void SWIG_RubyUnlinkObjects(void* ptr) {
  VALUE object = SWIG_RubyInstanceFor(ptr);

  if (object != Qnil) {
    DATA_PTR(object) = 0;
  }
}


#ifdef __cplusplus
}
#endif