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/* go-assert-interface.c -- interface type assertion for Go.
Copyright 2010 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 "runtime.h"
#include "go-alloc.h"
#include "go-assert.h"
#include "go-panic.h"
#include "go-type.h"
#include "interface.h"
/* This is called by the compiler to implement a type assertion from
one interface type to another. This returns the value that should
go in the first field of the result tuple. The result may be an
empty or a non-empty interface. */
const void *
__go_assert_interface (const struct __go_type_descriptor *lhs_descriptor,
const struct __go_type_descriptor *rhs_descriptor)
{
const struct __go_interface_type *lhs_interface;
if (rhs_descriptor == NULL)
{
struct __go_empty_interface panic_arg;
/* A type assertion is not permitted with a nil interface. */
runtime_newTypeAssertionError (NULL, NULL, lhs_descriptor->__reflection,
NULL, &panic_arg);
__go_panic (panic_arg);
}
/* A type assertion to an empty interface just returns the object
descriptor. */
__go_assert (lhs_descriptor->__code == GO_INTERFACE);
lhs_interface = (const struct __go_interface_type *) lhs_descriptor;
if (lhs_interface->__methods.__count == 0)
return rhs_descriptor;
return __go_convert_interface_2 (lhs_descriptor, rhs_descriptor, 0);
}
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