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