Module: HashUnnest

Defined in:
lib/hash_unnest.rb,
lib/hash_unnest/version.rb,
ext/hash_unnest/hash_unnest.c

Defined Under Namespace

Classes: CHnBuf, CInt

Constant Summary collapse

VERSION = 
'1.0.1'.freeze

Instance Method Summary collapse

Instance Method Details

#unnest ⇒ Object 



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# File 'lib/hash_unnest.rb', line 4

def unnest
  unnest_c
end

#unnest_c ⇒ Object

***************************************************************************



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# File 'ext/hash_unnest/hash_unnest.c', line 198

static VALUE hn_unnest(VALUE self)
{
  VALUE result, in, buf, prefix;
  hn_buffer_t* c_buf = NULL;
  int size = 0;

#ifdef DEBUG
  {
    VALUE _str_self   = rb_funcall(self,   rb_intern("to_s"), 0);
    LOG("*** hn_unnest (%s)\n", StringValueCStr(_str_self));
  }
#endif

  // count leaves in input
  rb_hash_foreach(
      self,
      hn_size_closure,
      Data_Wrap_Struct(hn_int_type, NULL, NULL, &size)
  );

#ifdef DEBUG
  {
    VALUE _str_self   = rb_funcall(self,   rb_intern("to_s"), 0);
    LOG("*** size(%s): %d\n", StringValueCStr(_str_self), size);
  }
#endif

  // unnest `self` into `buf`
  prefix = rb_str_new("", 0);
  buf = hn_buffer_alloc(size);

  in = rb_ary_new2(2);
  rb_ary_store(in, 0, prefix);
  rb_ary_store(in, 1, buf);
  
  rb_hash_foreach(self, hn_unnest_closure, in);

  // sort the C array of key, value pairs
  Data_Get_Struct(buf, hn_buffer_t, c_buf);
  assert(c_buf != NULL);
  assert(c_buf->buf != NULL);
  assert(c_buf->magic == BUFFER_MAGIC);
  assert(c_buf->cursor == size);

  qsort((void*) c_buf->buf, c_buf->cursor, sizeof(hn_entry_t), hn_entry_compare);

  // copy the array into a new hash
  result = rb_hash_new();

  for (int k = 0; k < c_buf->cursor; ++k) {
    hn_entry_t entry = c_buf->buf[k];

    assert(entry.magic == RECORD_MAGIC);
    assert(entry.key != Qnil);
    assert(entry.value != Qnil);
    rb_hash_aset(result, entry.key, entry.value);
  }

  return result;
}