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bce1f5ef4a
Currently ignored, but this will allow future compilers to pass down source location information for cast failure runtime errors without backward deployment constraints.
250 lines
9.8 KiB
C++
250 lines
9.8 KiB
C++
//===--- Casting.h - Swift type-casting runtime support ---------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Swift runtime functions for casting values.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_RUNTIME_CASTING_H
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#define SWIFT_RUNTIME_CASTING_H
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#include "swift/Runtime/Metadata.h"
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namespace swift {
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/// Perform a checked dynamic cast of a value to a target type.
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///
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/// \param dest A buffer into which to write the destination value.
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/// In all cases, this will be left uninitialized if the cast fails.
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///
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/// \param src Pointer to the source value to cast. This may be left
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/// uninitialized after the operation, depending on the flags.
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///
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/// \param targetType The type to which we are casting.
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///
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/// \param srcType The static type of the source value.
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///
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/// \param flags Flags to control the operation.
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///
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/// \return true if the cast succeeded. Depending on the flags,
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/// swift_dynamicCast may fail rather than return false.
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SWIFT_RUNTIME_EXPORT
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bool
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swift_dynamicCast(OpaqueValue *dest, OpaqueValue *src,
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const Metadata *srcType,
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const Metadata *targetType,
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DynamicCastFlags flags);
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/// Checked dynamic cast to a Swift class type.
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///
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/// \param object The object to cast.
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/// \param targetType The type to which we are casting, which is known to be
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/// a Swift class type.
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///
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/// \returns the object if the cast succeeds, or null otherwise.
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SWIFT_RUNTIME_EXPORT
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const void *
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swift_dynamicCastClass(const void *object, const ClassMetadata *targetType);
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/// Unconditional, checked dynamic cast to a Swift class type.
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///
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/// Aborts if the object isn't of the target type.
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///
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/// \param object The object to cast.
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/// \param targetType The type to which we are casting, which is known to be
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/// a Swift class type.
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/// \param file The source filename from which to report failure. May be null.
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/// \param line The source line from which to report failure.
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/// \param column The source column from which to report failure.
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///
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/// \returns the object.
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SWIFT_RUNTIME_EXPORT
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const void *
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swift_dynamicCastClassUnconditional(const void *object,
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const ClassMetadata *targetType,
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const char *file, unsigned line, unsigned column);
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#if SWIFT_OBJC_INTEROP
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/// Checked Objective-C-style dynamic cast to a class type.
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///
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/// \param object The object to cast, or nil.
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/// \param targetType The type to which we are casting, which is known to be
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/// a class type, but not necessarily valid type metadata.
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///
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/// \returns the object if the cast succeeds, or null otherwise.
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SWIFT_RUNTIME_EXPORT
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const void *
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swift_dynamicCastObjCClass(const void *object, const ClassMetadata *targetType);
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/// Checked dynamic cast to a foreign class type.
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///
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/// \param object The object to cast, or nil.
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/// \param targetType The type to which we are casting, which is known to be
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/// a foreign class type.
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///
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/// \returns the object if the cast succeeds, or null otherwise.
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SWIFT_RUNTIME_EXPORT
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const void *
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swift_dynamicCastForeignClass(const void *object,
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const ForeignClassMetadata *targetType);
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/// Unconditional, checked, Objective-C-style dynamic cast to a class
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/// type.
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///
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/// Aborts if the object isn't of the target type.
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/// Note that unlike swift_dynamicCastClassUnconditional, this does not abort
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/// if the object is 'nil'.
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///
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/// \param object The object to cast, or nil.
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/// \param targetType The type to which we are casting, which is known to be
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/// a class type, but not necessarily valid type metadata.
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/// \param file The source filename from which to report failure. May be null.
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/// \param line The source line from which to report failure.
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/// \param column The source column from which to report failure.
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///
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/// \returns the object.
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SWIFT_RUNTIME_EXPORT
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const void *
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swift_dynamicCastObjCClassUnconditional(const void *object,
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const ClassMetadata *targetType,
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const char *file, unsigned line, unsigned column);
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/// Unconditional, checked dynamic cast to a foreign class type.
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///
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/// \param object The object to cast, or nil.
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/// \param targetType The type to which we are casting, which is known to be
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/// a foreign class type.
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/// \param file The source filename from which to report failure. May be null.
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/// \param line The source line from which to report failure.
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/// \param column The source column from which to report failure.
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///
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/// \returns the object if the cast succeeds, or null otherwise.
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SWIFT_RUNTIME_EXPORT
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const void *
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swift_dynamicCastForeignClassUnconditional(
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const void *object,
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const ForeignClassMetadata *targetType,
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const char *file, unsigned line, unsigned column);
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#endif
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/// Checked dynamic cast of a class instance pointer to the given type.
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///
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/// \param object The class instance to cast.
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///
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/// \param targetType The type to which we are casting, which may be either a
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/// class type or a wrapped Objective-C class type.
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///
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/// \returns the object, or null if it doesn't have the given target type.
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SWIFT_RUNTIME_EXPORT
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const void *
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swift_dynamicCastUnknownClass(const void *object, const Metadata *targetType);
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/// Unconditional checked dynamic cast of a class instance pointer to
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/// the given type.
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///
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/// Aborts if the object isn't of the target type.
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///
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/// \param object The class instance to cast.
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///
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/// \param targetType The type to which we are casting, which may be either a
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/// class type or a wrapped Objective-C class type.
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///
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/// \param file The source filename from which to report failure. May be null.
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/// \param line The source line from which to report failure.
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/// \param column The source column from which to report failure.
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///
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/// \returns the object.
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SWIFT_RUNTIME_EXPORT
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const void *
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swift_dynamicCastUnknownClassUnconditional(const void *object,
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const Metadata *targetType,
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const char *file, unsigned line, unsigned column);
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SWIFT_RUNTIME_EXPORT
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const Metadata *
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swift_dynamicCastMetatype(const Metadata *sourceType,
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const Metadata *targetType);
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SWIFT_RUNTIME_EXPORT
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const Metadata *
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swift_dynamicCastMetatypeUnconditional(const Metadata *sourceType,
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const Metadata *targetType,
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const char *file, unsigned line, unsigned column);
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#if SWIFT_OBJC_INTEROP
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SWIFT_RUNTIME_EXPORT
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const ClassMetadata *
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swift_dynamicCastObjCClassMetatype(const ClassMetadata *sourceType,
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const ClassMetadata *targetType);
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SWIFT_RUNTIME_EXPORT
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const ClassMetadata *
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swift_dynamicCastObjCClassMetatypeUnconditional(const ClassMetadata *sourceType,
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const ClassMetadata *targetType,
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const char *file, unsigned line, unsigned column);
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#endif
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SWIFT_RUNTIME_EXPORT
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const ClassMetadata *
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swift_dynamicCastForeignClassMetatype(const ClassMetadata *sourceType,
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const ClassMetadata *targetType);
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SWIFT_RUNTIME_EXPORT
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const ClassMetadata *
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swift_dynamicCastForeignClassMetatypeUnconditional(
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const ClassMetadata *sourceType,
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const ClassMetadata *targetType,
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const char *file, unsigned line, unsigned column);
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/// Return the dynamic type of an opaque value.
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///
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/// \param value An opaque value.
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/// \param self The static type metadata for the opaque value and the result
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/// type value.
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/// \param existentialMetatype Whether the result type value is an existential
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/// metatype. If `self` is an existential type,
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/// then a `false` value indicates that the result
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/// is of concrete metatype type `self.Protocol`,
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/// and existential containers will not be projected
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/// through. A `true` value indicates that the result
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/// is of existential metatype type `self.Type`,
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/// so existential containers can be projected
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/// through as long as a subtype relationship holds
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/// from `self` to the contained dynamic type.
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SWIFT_RUNTIME_EXPORT
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const Metadata *
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swift_getDynamicType(OpaqueValue *value, const Metadata *self,
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bool existentialMetatype);
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/// Fetch the type metadata associated with the formal dynamic
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/// type of the given (possibly Objective-C) object. The formal
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/// dynamic type ignores dynamic subclasses such as those introduced
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/// by KVO.
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///
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/// The object pointer may be a tagged pointer, but cannot be null.
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SWIFT_RUNTIME_EXPORT
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const Metadata *swift_getObjectType(HeapObject *object);
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/// Check whether a type conforms to a given native Swift protocol,
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/// visible from the named module.
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///
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/// If so, returns a pointer to the witness table for its conformance.
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/// Returns void if the type does not conform to the protocol.
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///
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/// \param type The metadata for the type for which to do the conformance
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/// check.
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/// \param protocol The protocol descriptor for the protocol to check
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/// conformance for.
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SWIFT_RUNTIME_EXPORT
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const WitnessTable *swift_conformsToProtocol(const Metadata *type,
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const ProtocolDescriptor *protocol);
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} // end namespace swift
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#endif /* SWIFT_RUNTIME_CASTING_H */
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