jerryscript/jerry-core/vm/opcodes-for-in.cpp

/* Copyright 2015 Samsung Electronics Co., Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "jrt.h"
#include "opcodes.h"
#include "opcodes-ecma-support.h"

/**
 * Enumerate properties and construct collection with their
 * names for further iteration in for-in opcode handler.
 *
 * See also:
 *          ECMA-262 v5, 12.6.4
 *
 * @return header of constructed strings collection (should be freed with ecma_free_values_collection),
 *         or NULL - if there are no properties to enumerate in for-in.
 */
static ecma_collection_header_t *
vm_helper_for_in_enumerate_properties_names (ecma_object_t *obj_p) /**< starting object - result of ToObject
                                                                    *   conversion (ECMA-262 v5, 12.6.4, step 4) */
{
  const size_t bitmap_row_size = sizeof (uint32_t) * JERRY_BITSINBYTE;
  uint32_t names_hashes_bitmap[(1u << LIT_STRING_HASH_BITS) / bitmap_row_size];

  memset (names_hashes_bitmap, 0, sizeof (names_hashes_bitmap));

  ecma_length_t all_properties_count = 0;

  /* First pass: counting properties */
  for (ecma_object_t *prototype_chain_iter_p = obj_p;
       prototype_chain_iter_p != NULL;
       prototype_chain_iter_p = ecma_get_object_prototype (prototype_chain_iter_p))
  {
    for (ecma_property_t *prop_iter_p = ecma_get_property_list (prototype_chain_iter_p);
         prop_iter_p != NULL;
         prop_iter_p = ECMA_GET_POINTER (ecma_property_t, prop_iter_p->next_property_p))
    {
      if (prop_iter_p->type == ECMA_PROPERTY_NAMEDDATA
          || prop_iter_p->type == ECMA_PROPERTY_NAMEDACCESSOR)
      {
        all_properties_count++;
      }
      else
      {
        JERRY_ASSERT (prop_iter_p->type == ECMA_PROPERTY_INTERNAL);
      }
    }
  }

  if (all_properties_count == 0)
  {
    return NULL;
  }

  ecma_collection_header_t *ret_p = NULL;

  /* Second pass: collecting properties names */
  MEM_DEFINE_LOCAL_ARRAY (names_p, all_properties_count, ecma_string_t*);

  ecma_length_t enumerated_properties_count = 0;
  ecma_length_t non_enumerated_properties_count = 0;

  for (ecma_object_t *prototype_chain_iter_p = obj_p;
       prototype_chain_iter_p != NULL;
       prototype_chain_iter_p = ecma_get_object_prototype (prototype_chain_iter_p))
  {
    for (ecma_property_t *prop_iter_p = ecma_get_property_list (prototype_chain_iter_p);
         prop_iter_p != NULL;
         prop_iter_p = ECMA_GET_POINTER (ecma_property_t, prop_iter_p->next_property_p))
    {
      if (prop_iter_p->type == ECMA_PROPERTY_NAMEDDATA
          || prop_iter_p->type == ECMA_PROPERTY_NAMEDACCESSOR)
      {
        bool is_enumerated;

        ecma_string_t *prop_name_p;

        if (prop_iter_p->type == ECMA_PROPERTY_NAMEDDATA)
        {
          prop_name_p = ECMA_GET_NON_NULL_POINTER (ecma_string_t, prop_iter_p->u.named_data_property.name_p);
        }
        else
        {
          prop_name_p = ECMA_GET_NON_NULL_POINTER (ecma_string_t, prop_iter_p->u.named_accessor_property.name_p);
        }

        lit_string_hash_t hash = prop_name_p->hash;
        uint32_t bitmap_row = hash / bitmap_row_size;
        uint32_t bitmap_column = hash % bitmap_row_size;

        if (ecma_is_property_enumerable (prop_iter_p))
        {
          if ((names_hashes_bitmap[bitmap_row] & (1u << bitmap_column)) == 0)
          {
            /* no name with the hash occured during the iteration session */
            is_enumerated = true;
          }
          else
          {
            /* name with same hash already occured */
            bool is_equal_found = false;

            for (uint32_t index = 0;
                 !is_equal_found && index < enumerated_properties_count;
                 index++)
            {
              if (ecma_compare_ecma_strings (prop_name_p,
                                             names_p[index]))
              {
                is_equal_found = true;
              }
            }

            for (uint32_t index = 0;
                 !is_equal_found && index < non_enumerated_properties_count;
                 index++)
            {
              if (ecma_compare_ecma_strings (prop_name_p,
                                             names_p[all_properties_count - index - 1]))
              {
                is_equal_found = true;
              }
            }

            is_enumerated = !is_equal_found;
          }
        }
        else
        {
          is_enumerated = false;
        }

        names_hashes_bitmap[bitmap_row] |= (1u << bitmap_column);

        if (is_enumerated)
        {
          names_p[enumerated_properties_count++] = prop_name_p;
        }
        else
        {
          names_p[all_properties_count - non_enumerated_properties_count++ - 1] = prop_name_p;
        }

        JERRY_ASSERT (enumerated_properties_count + non_enumerated_properties_count <= all_properties_count);
      }
      else
      {
        JERRY_ASSERT (prop_iter_p->type == ECMA_PROPERTY_INTERNAL);
      }
    }
  }

  if (enumerated_properties_count != 0)
  {
    ret_p = ecma_new_strings_collection (names_p, enumerated_properties_count);
  }

  MEM_FINALIZE_LOCAL_ARRAY (names_p);

  return ret_p;
} /* vm_helper_for_in_enumerate_properties_names */

/**
 * 'for-in' opcode handler
 *
 * See also:
 *          ECMA-262 v5, 12.6.4
 *
 * @return completion value
 *         Returned value must be freed with ecma_free_completion_value
 */
ecma_completion_value_t
opfunc_for_in (opcode_t opdata, /**< operation data */
               int_data_t *int_data_p) /**< interpreter context */
{
  const idx_t expr_idx = opdata.data.for_in.expr;
  const idx_t block_end_oc_idx_1 = opdata.data.for_in.oc_idx_1;
  const idx_t block_end_oc_idx_2 = opdata.data.for_in.oc_idx_2;
  const opcode_counter_t for_in_end_oc = (opcode_counter_t) (
    calc_opcode_counter_from_idx_idx (block_end_oc_idx_1,
                                      block_end_oc_idx_2) + int_data_p->pos);

  ecma_completion_value_t ret_value = ecma_make_empty_completion_value ();

  /* 1., 2. */
  ECMA_TRY_CATCH (expr_value,
                  get_variable_value (int_data_p,
                                      expr_idx,
                                      false),
                  ret_value);

  int_data_p->pos++;

  opcode_t meta_opcode = vm_get_opcode (int_data_p->opcodes_p, for_in_end_oc);
  JERRY_ASSERT (meta_opcode.op_idx == __op__idx_meta);
  JERRY_ASSERT (meta_opcode.data.meta.type == OPCODE_META_TYPE_END_FOR_IN);

  /* 3. */
  if (!ecma_is_value_undefined (expr_value)
      && !ecma_is_value_null (expr_value))
  {
    /* 4. */
    ECMA_TRY_CATCH (obj_expr_value,
                    ecma_op_to_object (expr_value),
                    ret_value);

    ecma_object_t *obj_p = ecma_get_object_from_value (obj_expr_value);

    ecma_collection_iterator_t names_iterator;
    ecma_collection_header_t *names_p = vm_helper_for_in_enumerate_properties_names (obj_p);

    if (names_p != NULL)
    {
      ecma_collection_iterator_init (&names_iterator, names_p);

      const opcode_counter_t for_in_body_begin_oc = int_data_p->pos;
      const opcode_counter_t for_in_body_end_oc = for_in_end_oc;

      while (ecma_collection_iterator_next (&names_iterator))
      {
        ecma_value_t name_value = *names_iterator.current_value_p;

        ecma_string_t *name_p = ecma_get_string_from_value (name_value);

        if (ecma_op_object_get_property (obj_p, name_p) != NULL)
        {
          ecma_completion_value_t completion = set_variable_value (int_data_p,
                                                                   int_data_p->pos,
                                                                   OPCODE_REG_SPECIAL_FOR_IN_PROPERTY_NAME,
                                                                   name_value);
          JERRY_ASSERT (ecma_is_completion_value_empty (completion));

          vm_run_scope_t run_scope_for_in = { for_in_body_begin_oc, for_in_body_end_oc };

          ecma_completion_value_t for_in_body_completion = vm_loop (int_data_p, &run_scope_for_in);
          if (ecma_is_completion_value_empty (for_in_body_completion))
          {
            JERRY_ASSERT (int_data_p->pos == for_in_body_end_oc);

            int_data_p->pos = for_in_body_begin_oc;
          }
          else
          {
            JERRY_ASSERT (ecma_is_completion_value_throw (for_in_body_completion)
                          || ecma_is_completion_value_return (for_in_body_completion)
                          || ecma_is_completion_value_jump (for_in_body_completion));
            JERRY_ASSERT (int_data_p->pos <= for_in_body_end_oc);

            ret_value = for_in_body_completion;
            break;
          }
        }
      }

      ecma_free_values_collection (names_p, true);
    }

    ECMA_FINALIZE (obj_expr_value);
  }

  int_data_p->pos = (opcode_counter_t) (for_in_end_oc + 1u);

  ECMA_FINALIZE (expr_value);

  return ret_value;
} /* opfunc_for_in */