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/* go-can-convert-interface.c -- can we convert to an interface?

   Copyright 2009 The Go Authors. All rights reserved.

   Use of this source code is governed by a BSD-style

   license that can be found in the LICENSE file.  */

#include "go-assert.h"

#include "go-type.h"

#include "interface.h"

/* Return whether we can convert from the type in FROM_DESCRIPTOR to

   the interface in TO_DESCRIPTOR.  This is used for type

   switches.  */

_Bool

__go_can_convert_to_interface (

    const struct __go_type_descriptor *to_descriptor,

    const struct __go_type_descriptor *from_descriptor)

{

  const struct __go_interface_type *to_interface;

  int to_method_count;

  const struct __go_interface_method *to_method;

  const struct __go_uncommon_type *from_uncommon;

  int from_method_count;

  const struct __go_method *from_method;

  int i;

  /* In a type switch FROM_DESCRIPTOR can be NULL.  */

  if (from_descriptor == NULL)

    return 0;

  __go_assert (to_descriptor->__code == GO_INTERFACE);

  to_interface = (const struct __go_interface_type *) to_descriptor;

  to_method_count = to_interface->__methods.__count;

  to_method = ((const struct __go_interface_method *)

               to_interface->__methods.__values);

  from_uncommon = from_descriptor->__uncommon;

  if (from_uncommon == NULL)

    {

      from_method_count = 0;

      from_method = NULL;

    }

  else

    {

      from_method_count = from_uncommon->__methods.__count;

      from_method = ((const struct __go_method *)

                     from_uncommon->__methods.__values);

    }

  for (i = 0; i < to_method_count; ++i)

    {

      while (from_method_count > 0

             && (!__go_ptr_strings_equal (from_method->__name,

                                          to_method->__name)

                 || !__go_ptr_strings_equal (from_method->__pkg_path,

                                             to_method->__pkg_path)))

        {

          ++from_method;

          --from_method_count;

        }

      if (from_method_count == 0)

        return 0;

      if (!__go_type_descriptors_equal (from_method->__mtype,

                                        to_method->__type))

        return 0;

      ++to_method;

      ++from_method;

      --from_method_count;

    }

  return 1;

}