text: /**
   * @file objref.c
   * @author Ambroz Bizjak <ambrop7@gmail.com>
   * 
   * @section LICENSE
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the author nor the
   *    names of its contributors may be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
   * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   * 
   * @section DESCRIPTION
   * 
   * Synopsis:
   *   objref(list(string) target)
   *   objref_arg(list(string) target)
   */
  
  #include <misc/debug.h>
  #include <misc/balloc.h>
  
  #include <ncd/module_common.h>
  
  #include <generated/blog_channel_ncd_objref.h>
  
  struct instance {
      NCDModuleInst *i;
      NCDObjRef ref;
  };
  
  static void func_new_common (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params, int is_arg)
  {
      ASSERT(is_arg == 0 || is_arg == 1)
      
      struct instance *o = vo;
      o->i = i;
      
      NCDValRef target_arg;
      if (!NCDVal_ListRead(params->args, 1, &target_arg)) {
          ModuleLog(i, BLOG_ERROR, "wrong arity");
          goto fail0;
      }
      
      if (!NCDVal_IsList(target_arg)) {
          ModuleLog(i, BLOG_ERROR, "argument is not a list");
          goto fail0;
      }
      
      size_t num_names = NCDVal_ListCount(target_arg);
      if (num_names == 0) {
          ModuleLog(i, BLOG_ERROR, "target list is empty");
          goto fail0;
      }
      
      size_t total_names = is_arg + num_names;
      
      NCD_string_id_t *names = BAllocArray(total_names, sizeof(*names));
      if (!names) {
          ModuleLog(i, BLOG_ERROR, "BAllocArray failed");
          goto fail0;
      }
      
      if (is_arg) {
          names[0] = NCD_STRING_CALLER;
      }
      
      for (size_t j = 0; j < num_names; j++) {
          NCDValRef name_val = NCDVal_ListGet(target_arg, j);
          
          if (!NCDVal_IsString(name_val)) {
              ModuleLog(i, BLOG_ERROR, "target component is not a string");
              goto fail1;
          }
          
          NCD_string_id_t name_id = ncd_get_string_id(name_val);
          if (name_id < 0) {
              ModuleLog(i, BLOG_ERROR, "ncd_get_string_id failed");
              goto fail1;
          }
          
          names[is_arg + j] = name_id;
      }
      
      NCDObject first_obj;
      if (!NCDModuleInst_Backend_GetObj(i, names[0], &first_obj)) {
          ModuleLog(i, BLOG_ERROR, "first target object not found");
          goto fail1;
      }
      
      NCDObject obj;
      if (!NCDObject_ResolveObjExprCompact(&first_obj, names + 1, total_names - 1, &obj)) {
          ModuleLog(i, BLOG_ERROR, "non-first target object not found");
          goto fail1;
      }
      
      NCDPersistentObj *pobj = NCDObject_Pobj(&obj);
      if (!pobj) {
          ModuleLog(i, BLOG_ERROR, "object does not support references");
          goto fail1;
      }
      
      NCDObjRef_Init(&o->ref, pobj);
      
      BFree(names);
      
      NCDModuleInst_Backend_Up(i);
      return;
      
  fail1:
      BFree(names);
  fail0:
      NCDModuleInst_Backend_DeadError(i);
  }
  
  static void func_new_objref (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
  {
      func_new_common(vo, i, params, 0);
  }
  
  static void func_new_objref_arg (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
  {
      func_new_common(vo, i, params, 1);
  }
  
  static void func_die (void *vo)
  {
      struct instance *o = vo;
      
      NCDObjRef_Free(&o->ref);
      
      NCDModuleInst_Backend_Dead(o->i);
  }
  
  static int func_getobj (void *vo, NCD_string_id_t name, NCDObject *out_object)
  {
      struct instance *o = vo;
      
      NCDObject obj;
      if (!NCDObjRef_Deref(&o->ref, &obj)) {
          ModuleLog(o->i, BLOG_ERROR, "object reference has been broken");
          return 0;
      }
      
      if (name == NCD_STRING_EMPTY) {
          *out_object = obj;
          return 1;
      }
      
      return NCDObject_GetObj(&obj, name, out_object);
  }
  
  static struct NCDModule modules[] = {
      {
          .type = "objref",
          .func_new2 = func_new_objref,
          .func_die = func_die,
          .func_getobj = func_getobj,
          .alloc_size = sizeof(struct instance)
      }, {
          .type = "objref_arg",
          .func_new2 = func_new_objref_arg,
          .func_die = func_die,
          .func_getobj = func_getobj,
          .alloc_size = sizeof(struct instance)
      }, {
          .type = NULL
      }
  };
  
  const struct NCDModuleGroup ncdmodule_objref = {
      .modules = modules
  };
  