lbm_custom_type.h

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/*
    Copyright 2022, 2024 Joel Svensson        svenssonjoel@yahoo.se
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef LBM_CUSTOM_TYPE_H_
#define LBM_CUSTOM_TYPE_H_
 
#include <stdbool.h>
#include <stddef.h>
#include <lbm_types.h>
#include <lbm_defines.h>
#include <heap.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
// Custom type lbm_memory footprint
#define CUSTOM_TYPE_VALUE        0
#define CUSTOM_TYPE_DESCRIPTOR   1
#define CUSTOM_TYPE_DESTRUCTOR   2
#define CUSTOM_TYPE_LBM_MEM_SIZE 3
 
// encoding
//
// ( lbm-mem-ptr . LBM_TYPE_CUSTOM_SYM )
//     |
//     pointer to lbm_memory
//
 
typedef bool (*custom_type_destructor)(lbm_uint);
 
bool lbm_custom_type_create(lbm_uint value, custom_type_destructor fptr, const char *desc, lbm_value *result);  
 
bool lbm_custom_type_destroy(lbm_uint *lbm_mem_ptr);
 
static inline bool lbm_is_custom(lbm_value value) {
  lbm_value v = lbm_dec_custom(value);
  // SYM_NIL has bit pattern 0
  // dec_custom returns zero when type is not custom.
  return (v != 0); // lbm_type_of(value) == LBM_TYPE_CUSTOM && !lbm_is_symbol_nil(lbm_car(value)));
}
 
// Must check is_custom before calling get_custom_descriptor
static inline const char *lbm_get_custom_descriptor(lbm_value value) {
  lbm_uint *m = (lbm_uint*)(lbm_ref_cell(value)->car);
  return (const char*)m[CUSTOM_TYPE_DESCRIPTOR];
}
 
// Must check is_custom before calling get_custom_descriptor
static inline lbm_uint lbm_get_custom_value(lbm_value value) {
  lbm_uint *m = (lbm_uint*)lbm_dec_custom(value);
  if (m) {
    return m[CUSTOM_TYPE_VALUE];
  }
  return 0;
}
 
#ifdef __cplusplus
}
#endif
#endif