libgo/runtime/go-interface-eface-compare.c

   1 /* go-interface-eface-compare.c -- compare non-empty and empty interface.
   2
   3    Copyright 2011 The Go Authors. All rights reserved.
   4    Use of this source code is governed by a BSD-style
   5    license that can be found in the LICENSE file.  */
   6
   7 #include "runtime.h"
   8 #include "go-type.h"
   9 #include "interface.h"
  10
  11 /* Compare a non-empty interface value with an empty interface value.
  12    Return 0 for equal, not zero for not equal (return value is like
  13    strcmp).  */
  14
  15 intgo
  16 __go_interface_empty_compare (struct __go_interface left,
  17                               struct __go_empty_interface right)
  18 {
  19   const struct __go_type_descriptor *left_descriptor;
  20
  21   if (((uintptr_t) right.__type_descriptor & reflectFlags) != 0)
  22     runtime_panicstring ("invalid interface value");
  23   if (left.__methods == NULL && right.__type_descriptor == NULL)
  24     return 0;
  25   if (left.__methods == NULL || right.__type_descriptor == NULL)
  26     return 1;
  27   left_descriptor = left.__methods[0];
  28   if (!__go_type_descriptors_equal (left_descriptor, right.__type_descriptor))
  29     return 1;
  30   if (__go_is_pointer_type (left_descriptor))
  31     return left.__object == right.__object ? 0 : 1;
  32   if (!left_descriptor->__equalfn (left.__object, right.__object,
  33                                    left_descriptor->__size))
  34     return 1;
  35   return 0;
  36 }