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fuchsia / third_party / swift / ba9946a1319f26743702540447343eb46d47de85 / . / stdlib / public / runtime / Casting.cpp
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//===--- Casting.cpp - Swift Language Dynamic Casting Support -------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// Implementations of the dynamic cast runtime functions.
//
//===----------------------------------------------------------------------===//
#include "swift/Runtime/Casting.h"
#include "../SwiftShims/RuntimeShims.h"
#include "ErrorObject.h"
#include "ExistentialMetadataImpl.h"
#include "Private.h"
#include "SwiftHashableSupport.h"
#include "stddef.h"
#include "swift/Basic/LLVM.h"
#include "swift/Basic/Lazy.h"
#include "swift/Demangling/Demangler.h"
#include "swift/Runtime/Config.h"
#include "swift/Runtime/Debug.h"
#include "swift/Runtime/Enum.h"
#include "swift/Runtime/ExistentialContainer.h"
#include "swift/Runtime/HeapObject.h"
#include "swift/Runtime/Metadata.h"
#include "swift/Runtime/Mutex.h"
#include "swift/Runtime/Unreachable.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/Support/Compiler.h"
#if SWIFT_OBJC_INTEROP
#include "swift/Runtime/ObjCBridge.h"
#include "SwiftValue.h"
#endif
#include <cstring>
#include <type_traits>
using namespace swift;
using namespace swift::hashable_support;
using namespace metadataimpl;
#if SWIFT_OBJC_INTEROP
#include <objc/NSObject.h>
#include <objc/runtime.h>
#include <objc/message.h>
#include <objc/objc.h>
// Aliases for Objective-C runtime entry points.
static const char *class_getName(const ClassMetadata* type) {
return class_getName(
reinterpret_cast<Class>(const_cast<ClassMetadata*>(type)));
}
// Aliases for Swift runtime entry points for Objective-C types.
extern "C" const void *swift_dynamicCastObjCProtocolConditional(
const void *object,
size_t numProtocols,
const ProtocolDescriptor * const *protocols);
#endif
// Build a user-comprehensible name for a type.
static void _buildNameForMetadata(const Metadata *type,
bool qualified,
std::string &result) {
#if SWIFT_OBJC_INTEROP
if (type->getKind() == MetadataKind::Class) {
auto classType = static_cast<const ClassMetadata *>(type);
// Look through artificial subclasses.
while (classType->isTypeMetadata() && classType->isArtificialSubclass())
classType = classType->SuperClass;
// Ask the Objective-C runtime to name ObjC classes.
if (!classType->isTypeMetadata()) {
result += class_getName(classType);
return;
}
} else if (type->getKind() == MetadataKind::ObjCClassWrapper) {
auto objcWrapper = static_cast<const ObjCClassWrapperMetadata *>(type);
const char *className = class_getName(class_const_cast(objcWrapper->Class));
result = className;
return;
}
#endif
// Use the remangler to generate a mangled name from the type metadata.
Demangle::Demangler Dem;
// We want to resolve symbolic references to a user-comprehensible
// representation of the referenced context.
Dem.setSymbolicReferenceResolver(ResolveToDemanglingForContext(Dem));
auto demangling = _swift_buildDemanglingForMetadata(type, Dem);
if (demangling == nullptr) {
result = "<<< invalid type >>>";
return;
}
Demangle::DemangleOptions options;
options.QualifyEntities = qualified;
if (!qualified)
options.ShowPrivateDiscriminators = false;
result = Demangle::nodeToString(demangling, options);
}
/// Return a user-comprehensible name for the given type.
std::string swift::nameForMetadata(const Metadata *type,
bool qualified) {
std::string result;
_buildNameForMetadata(type, qualified, result);
return result;
}
TypeNamePair
swift::swift_getTypeName(const Metadata *type, bool qualified) {
using Key = llvm::PointerIntPair<const Metadata *, 1, bool>;
static StaticReadWriteLock TypeNameCacheLock;
static Lazy<llvm::DenseMap<Key, std::pair<const char *, size_t>>>
TypeNameCache;
Key key(type, qualified);
auto &cache = TypeNameCache.get();
// Attempt read-only lookup of cache entry.
{
StaticScopedReadLock guard(TypeNameCacheLock);
auto found = cache.find(key);
if (found != cache.end()) {
auto result = found->second;
return TypeNamePair{result.first, result.second};
}
}
// Read-only lookup failed to find item, we may need to create it.
{
StaticScopedWriteLock guard(TypeNameCacheLock);
// Do lookup again just to make sure it wasn't created by another
// thread before we acquired the write lock.
auto found = cache.find(key);
if (found != cache.end()) {
auto result = found->second;
return TypeNamePair{result.first, result.second};
}
// Build the metadata name.
auto name = nameForMetadata(type, qualified);
// Copy it to memory we can reference forever.
auto size = name.size();
auto result = (char *)malloc(size + 1);
memcpy(result, name.data(), size);
result[size] = 0;
cache.insert({key, {result, size}});
return TypeNamePair{result, size};
}
}
/// Report a dynamic cast failure.
// This is noinline to preserve this frame in stack traces.
// We want "dynamicCastFailure" to appear in crash logs even we crash
// during the diagnostic because some Metadata is invalid.
LLVM_ATTRIBUTE_NORETURN
LLVM_ATTRIBUTE_NOINLINE
void
swift::swift_dynamicCastFailure(const void *sourceType, const char *sourceName,
const void *targetType, const char *targetName,
const char *message) {
swift::fatalError(/* flags = */ 0,
"Could not cast value of type '%s' (%p) to '%s' (%p)%s%s\n",
sourceName, sourceType,
targetName, targetType,
message ? ": " : ".",
message ? message : "");
}
LLVM_ATTRIBUTE_NORETURN
void
swift::swift_dynamicCastFailure(const Metadata *sourceType,
const Metadata *targetType,
const char *message) {
std::string sourceName = nameForMetadata(sourceType);
std::string targetName = nameForMetadata(targetType);
swift_dynamicCastFailure(sourceType, sourceName.c_str(),
targetType, targetName.c_str(), message);
}
#if SWIFT_OBJC_INTEROP
// Objective-C bridging helpers.
namespace {
struct _ObjectiveCBridgeableWitnessTable;
}
static const _ObjectiveCBridgeableWitnessTable *
findBridgeWitness(const Metadata *T);
static bool _dynamicCastValueToClassViaObjCBridgeable(
OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const Metadata *targetType,
const _ObjectiveCBridgeableWitnessTable *srcBridgeWitness,
DynamicCastFlags flags);
static bool _dynamicCastValueToClassExistentialViaObjCBridgeable(
OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const ExistentialTypeMetadata *targetType,
const _ObjectiveCBridgeableWitnessTable *srcBridgeWitness,
DynamicCastFlags flags);
static bool _dynamicCastClassToValueViaObjCBridgeable(
OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const Metadata *targetType,
const _ObjectiveCBridgeableWitnessTable *targetBridgeWitness,
DynamicCastFlags flags);
#endif
/// A convenient method for failing out of a dynamic cast.
static bool _fail(OpaqueValue *srcValue, const Metadata *srcType,
const Metadata *targetType, DynamicCastFlags flags,
const Metadata *srcDynamicType = nullptr) {
if (flags & DynamicCastFlags::Unconditional) {
const Metadata *srcTypeToReport =
srcDynamicType ? srcDynamicType
: srcType;
swift_dynamicCastFailure(srcTypeToReport, targetType);
}
if (flags & DynamicCastFlags::DestroyOnFailure)
srcType->vw_destroy(srcValue);
return false;
}
/// A convenient method for succeeding at a dynamic cast.
static bool _succeed(OpaqueValue *dest, OpaqueValue *src,
const Metadata *srcType, DynamicCastFlags flags) {
if (flags & DynamicCastFlags::TakeOnSuccess) {
srcType->vw_initializeWithTake(dest, src);
} else {
srcType->vw_initializeWithCopy(dest, src);
}
return true;
}
/// Dynamically cast a class metatype to a Swift class metatype.
static const ClassMetadata *
_dynamicCastClassMetatype(const ClassMetadata *sourceType,
const ClassMetadata *targetType) {
do {
if (sourceType == targetType) {
return sourceType;
}
sourceType = sourceType->SuperClass;
} while (sourceType);
return nullptr;
}
/// Dynamically cast a class instance to a Swift class type.
const void *swift::swift_dynamicCastClass(const void *object,
const ClassMetadata *targetType) {
#if SWIFT_OBJC_INTEROP
assert(!targetType->isPureObjC());
// Swift native classes never have a tagged-pointer representation.
if (isObjCTaggedPointerOrNull(object)) {
return nullptr;
}
#endif
auto isa = _swift_getClassOfAllocated(object);
if (_dynamicCastClassMetatype(isa, targetType))
return object;
return nullptr;
}
/// Dynamically cast a class object to a Swift class type.
const void *
swift::swift_dynamicCastClassUnconditional(const void *object,
const ClassMetadata *targetType) {
auto value = swift_dynamicCastClass(object, targetType);
if (value) return value;
swift_dynamicCastFailure(_swift_getClass(object), targetType);
}
#if SWIFT_OBJC_INTEROP
static bool _unknownClassConformsToObjCProtocol(const OpaqueValue *value,
const ProtocolDescriptor *protocol) {
const void *object
= *reinterpret_cast<const void * const *>(value);
return swift_dynamicCastObjCProtocolConditional(object, 1, &protocol);
}
#endif
bool swift::_conformsToProtocol(const OpaqueValue *value,
const Metadata *type,
const ProtocolDescriptor *protocol,
const WitnessTable **conformance) {
// Look up the witness table for protocols that need them.
if (protocol->Flags.needsWitnessTable()) {
auto witness = swift_conformsToProtocol(type, protocol);
if (!witness)
return false;
if (conformance)
*conformance = witness;
return true;
}
// For Objective-C protocols, check whether we have a class that
// conforms to the given protocol.
switch (type->getKind()) {
case MetadataKind::Class:
#if SWIFT_OBJC_INTEROP
if (value) {
return _unknownClassConformsToObjCProtocol(value, protocol);
} else {
return classConformsToObjCProtocol(type, protocol);
}
#endif
return false;
case MetadataKind::ObjCClassWrapper: {
#if SWIFT_OBJC_INTEROP
if (value) {
return _unknownClassConformsToObjCProtocol(value, protocol);
} else {
auto wrapper = cast<ObjCClassWrapperMetadata>(type);
return classConformsToObjCProtocol(wrapper->Class, protocol);
}
#endif
return false;
}
case MetadataKind::ForeignClass:
#if SWIFT_OBJC_INTEROP
if (value)
return _unknownClassConformsToObjCProtocol(value, protocol);
return false;
#else
_failCorruptType(type);
#endif
case MetadataKind::Existential: // FIXME
case MetadataKind::ExistentialMetatype: // FIXME
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct:
case MetadataKind::Tuple:
return false;
}
return false;
}
/// Check whether a type conforms to the given protocols, filling in a
/// list of conformances.
static bool _conformsToProtocols(const OpaqueValue *value,
const Metadata *type,
const ExistentialTypeMetadata *existentialType,
const WitnessTable **conformances) {
if (auto *superclass = existentialType->getSuperclassConstraint()) {
if (!swift_dynamicCastMetatype(type, superclass))
return false;
}
if (existentialType->isClassBounded()) {
if (!Metadata::isAnyKindOfClass(type->getKind()))
return false;
}
auto &protocols = existentialType->Protocols;
for (unsigned i = 0, n = protocols.NumProtocols; i != n; ++i) {
const ProtocolDescriptor *protocol = protocols[i];
if (!_conformsToProtocol(value, type, protocol, conformances))
return false;
if (protocol->Flags.needsWitnessTable()) {
assert(*conformances != nullptr);
++conformances;
}
}
return true;
}
static bool shouldDeallocateSource(bool castSucceeded, DynamicCastFlags flags) {
return (castSucceeded && (flags & DynamicCastFlags::TakeOnSuccess)) ||
(!castSucceeded && (flags & DynamicCastFlags::DestroyOnFailure));
}
static bool
isAnyObjectExistentialType(const ExistentialTypeMetadata *targetType) {
unsigned numProtos = targetType->Protocols.NumProtocols;
return (numProtos == 0 &&
targetType->getSuperclassConstraint() == nullptr &&
targetType->isClassBounded());
}
/// Given a possibly-existential value, find its dynamic type and the
/// address of its storage.
static void
findDynamicValueAndType(OpaqueValue *value, const Metadata *type,
OpaqueValue *&outValue, const Metadata *&outType,
bool &inoutCanTake,
bool isTargetTypeAnyObject,
bool isTargetExistentialMetatype) {
switch (type->getKind()) {
case MetadataKind::Class:
case MetadataKind::ObjCClassWrapper:
case MetadataKind::ForeignClass: {
// TODO: avoid unnecessary repeat lookup of
// ObjCClassWrapper/ForeignClass when the type matches.
outValue = value;
outType = swift_getObjectType(*reinterpret_cast<HeapObject**>(value));
return;
}
case MetadataKind::Existential: {
auto existentialType = cast<ExistentialTypeMetadata>(type);
inoutCanTake &= existentialType->mayTakeValue(value);
// We can't drill through existential containers unless the result is an
// existential metatype.
if (!isTargetExistentialMetatype) {
outValue = value;
outType = type;
return;
}
switch (existentialType->getRepresentation()) {
case ExistentialTypeRepresentation::Class: {
// Class existentials can't recursively contain existential containers,
// so we can fast-path by not bothering to recur.
auto existential =
reinterpret_cast<ClassExistentialContainer*>(value);
outValue = (OpaqueValue*) &existential->Value;
outType = swift_getObjectType((HeapObject*) existential->Value);
return;
}
case ExistentialTypeRepresentation::Opaque:
case ExistentialTypeRepresentation::Error: {
const Metadata *innerType = existentialType->getDynamicType(value);
// Short cut class in existential as AnyObject casts.
if (isTargetTypeAnyObject &&
innerType->getKind() == MetadataKind::Class) {
// inline value buffer storage.
outValue = value;
outType = 0;
inoutCanTake = true;
return;
}
OpaqueValue *innerValue
= existentialType->projectValue(value);
return findDynamicValueAndType(innerValue, innerType,
outValue, outType, inoutCanTake, false,
isTargetExistentialMetatype);
}
}
}
case MetadataKind::Metatype:
case MetadataKind::ExistentialMetatype: {
auto storedType = *(const Metadata **) value;
outValue = value;
outType = swift_getMetatypeMetadata(storedType);
return;
}
// Non-polymorphic types.
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct:
case MetadataKind::Tuple:
outValue = value;
outType = type;
return;
}
_failCorruptType(type);
}
extern "C" const Metadata *
swift::swift_getDynamicType(OpaqueValue *value, const Metadata *self,
bool existentialMetatype) {
OpaqueValue *outValue;
const Metadata *outType;
bool canTake = false;
findDynamicValueAndType(value, self, outValue, outType, canTake,
/*isAnyObject*/ false,
existentialMetatype);
return outType;
}
/// Given a possibly-existential value, deallocate any buffer in its storage.
static void deallocateDynamicValue(OpaqueValue *value, const Metadata *type) {
switch (type->getKind()) {
case MetadataKind::Existential: {
auto existentialType = cast<ExistentialTypeMetadata>(type);
switch (existentialType->getRepresentation()) {
case ExistentialTypeRepresentation::Class:
// Nothing to clean up.
break;
case ExistentialTypeRepresentation::Error:
// TODO: We could clean up from a reclaimed uniquely-referenced error box.
break;
case ExistentialTypeRepresentation::Opaque:
swift::fatalError(
0 /* flags */,
"Attempting to move out of a copy-on-write existential");
break;
}
return;
}
// None of the rest of these require deallocation.
case MetadataKind::Class:
case MetadataKind::ForeignClass:
case MetadataKind::ObjCClassWrapper:
case MetadataKind::Metatype:
case MetadataKind::ExistentialMetatype:
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct:
case MetadataKind::Tuple:
return;
}
_failCorruptType(type);
}
#if SWIFT_OBJC_INTEROP
SWIFT_RUNTIME_EXPORT
id
swift_dynamicCastMetatypeToObjectConditional(const Metadata *metatype) {
switch (metatype->getKind()) {
case MetadataKind::Class:
case MetadataKind::ObjCClassWrapper:
// Swift classes are objects in and of themselves.
// ObjC class wrappers get unwrapped.
return (id)metatype->getObjCClassObject();
// Other kinds of metadata don't cast to AnyObject.
case MetadataKind::Struct:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Tuple:
case MetadataKind::Function:
case MetadataKind::Existential:
case MetadataKind::Metatype:
case MetadataKind::ExistentialMetatype:
case MetadataKind::ForeignClass:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
return nullptr;
}
}
SWIFT_RUNTIME_EXPORT
id
swift_dynamicCastMetatypeToObjectUnconditional(const Metadata *metatype) {
switch (metatype->getKind()) {
case MetadataKind::Class:
case MetadataKind::ObjCClassWrapper:
// Swift classes are objects in and of themselves.
// ObjC class wrappers get unwrapped.
return (id)metatype->getObjCClassObject();
// Other kinds of metadata don't cast to AnyObject.
case MetadataKind::Struct:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Tuple:
case MetadataKind::Function:
case MetadataKind::Existential:
case MetadataKind::Metatype:
case MetadataKind::ExistentialMetatype:
case MetadataKind::ForeignClass:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject: {
std::string sourceName = nameForMetadata(metatype);
swift_dynamicCastFailure(metatype, sourceName.c_str(),
nullptr, "AnyObject",
"only class metatypes can be converted to AnyObject");
}
}
}
// internal func _getErrorEmbeddedNSErrorIndirect<T : Error>(
// _ x: UnsafePointer<T>) -> AnyObject?
#define getErrorEmbeddedNSErrorIndirect \
MANGLE_SYM(s32_getErrorEmbeddedNSErrorIndirectyyXlSgSPyxGs0B0RzlF)
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
id getErrorEmbeddedNSErrorIndirect(const OpaqueValue *error,
const Metadata *T,
const WitnessTable *Error);
#endif
/******************************************************************************/
/******************************** AnyHashable *********************************/
/******************************************************************************/
/// Nominal type descriptor for Swift.AnyHashable.
extern "C" const StructDescriptor STRUCT_TYPE_DESCR_SYM(s11AnyHashable);
static bool isAnyHashableType(const StructMetadata *type) {
return type->getDescription() == &STRUCT_TYPE_DESCR_SYM(s11AnyHashable);
}
static bool isAnyHashableType(const Metadata *type) {
if (auto structType = dyn_cast<StructMetadata>(type)) {
return isAnyHashableType(structType);
}
return false;
}
/// Perform a dynamic cast from a nominal type to AnyHashable.
static bool _dynamicCastToAnyHashable(OpaqueValue *destination,
OpaqueValue *source,
const Metadata *sourceType,
const Metadata *targetType,
DynamicCastFlags flags) {
// Look for a conformance to Hashable.
auto hashableConformance = reinterpret_cast<const HashableWitnessTable *>(
swift_conformsToProtocol(sourceType, &HashableProtocolDescriptor));
// If we don't find one, the cast fails.
if (!hashableConformance) {
return _fail(source, sourceType, targetType, flags);
}
// If we do find one, the cast succeeds.
// The intrinsic wants the value at +1, so we have to copy it into
// a temporary.
ValueBuffer buffer;
bool mustDeallocBuffer = false;
if (!(flags & DynamicCastFlags::TakeOnSuccess)) {
auto *valueAddr = sourceType->allocateBufferIn(&buffer);
source = sourceType->vw_initializeWithCopy(valueAddr, source);
mustDeallocBuffer = true;
}
// Initialize the destination.
_swift_convertToAnyHashableIndirect(source, destination,
sourceType, hashableConformance);
// Deallocate the buffer if we used it.
if (mustDeallocBuffer) {
sourceType->deallocateBufferIn(&buffer);
}
// The cast succeeded.
return true;
}
/// Perform a dynamic cast to an arbitrary type from AnyHashable.
static bool _dynamicCastFromAnyHashable(OpaqueValue *destination,
OpaqueValue *source,
const Metadata *sourceType,
const Metadata *targetType,
DynamicCastFlags flags) {
// Perform a conditional, non-consuming cast into the destination.
if (_swift_anyHashableDownCastConditionalIndirect(source, destination,
targetType)) {
// If that succeeded, and we were supposed to claim the source,
// destroy it now.
if (flags & DynamicCastFlags::TakeOnSuccess) {
sourceType->vw_destroy(source);
}
return true;
}
return _fail(source, sourceType, targetType, flags);
}
/******************************************************************************/
/******************************** Existentials ********************************/
/******************************************************************************/
/// Perform a dynamic cast to an existential type.
static bool _dynamicCastToExistential(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const ExistentialTypeMetadata *targetType,
DynamicCastFlags flags) {
#if SWIFT_OBJC_INTEROP
// This variable's lifetime needs to be for the whole function, but is
// only valid with Objective-C interop enabled.
id tmp;
#endif
// Find the actual type of the source.
OpaqueValue *srcDynamicValue;
const Metadata *srcDynamicType;
bool canConsumeDynamicValue = true;
// Are we casting to AnyObject? In this case we can fast-path casts from
// classes.
bool isTargetTypeAnyObject =
targetType->getKind() == MetadataKind::Existential &&
isAnyObjectExistentialType(targetType);
// We don't care what the target type of a cast from class to AnyObject is.
// srcDynamicType will be set to a nullptr in this case to save a lookup.
findDynamicValueAndType(src, srcType, srcDynamicValue, srcDynamicType,
canConsumeDynamicValue, isTargetTypeAnyObject,
/*isExistentialMetatype*/ true);
// Recursive casts on the dynamic value should not destroy the source
// if findDynamicValueAndType doesn't allow it.
DynamicCastFlags dynamicFlags = flags;
if (!canConsumeDynamicValue) {
dynamicFlags = dynamicFlags - (DynamicCastFlags::TakeOnSuccess |
DynamicCastFlags::DestroyOnFailure);
}
// Given that we performed a cast on srcDynamicValue and obeyed
// dynamicFlags there, clean up after src.
auto maybeDeallocateSource = [&](bool success) {
// If the flags don't say to destroy src, we're done.
if (!shouldDeallocateSource(success, flags)) return;
// If findDynamicValueAndType didn't give us a consumable interior
// value, then src is still completely intact.
if (!canConsumeDynamicValue) {
srcType->vw_destroy(src);
// Otherwise, if we destroyed an interior value, we need to clean
// up any leftover buffers it may have been contained in.
} else if (src != srcDynamicValue) {
deallocateDynamicValue(src, srcType);
}
};
// A function to call if the dynamic type does not conform to the
// protocols. Typically fails, but if the source type is AnyHashable,
// tries to unwrap that.
auto fallbackForNonDirectConformance = [&] {
// As a fallback, if the source type is AnyHashable, perform a cast
// on its interior value.
if (isAnyHashableType(srcDynamicType)) {
bool success =
_dynamicCastFromAnyHashable(dest, srcDynamicValue, srcDynamicType,
targetType, dynamicFlags);
maybeDeallocateSource(success);
return success;
}
return _fail(src, srcType, targetType, flags, srcDynamicType);
};
// The representation of an existential is different for some protocols.
switch (targetType->getRepresentation()) {
case ExistentialTypeRepresentation::Class: {
auto destExistential =
reinterpret_cast<ClassExistentialContainer*>(dest);
MetadataKind kind =
srcDynamicType ? srcDynamicType->getKind() : MetadataKind::Class;
// A fallback to use if we don't have a more specialized approach
// for a non-class type.
auto fallbackForNonClass = [&] {
#if SWIFT_OBJC_INTEROP
// If the destination type is a set of protocols that SwiftValue
// implements, we're fine.
if (findSwiftValueConformances(targetType,
destExistential->getWitnessTables())) {
bool consumeValue = dynamicFlags & DynamicCastFlags::TakeOnSuccess;
destExistential->Value =
bridgeAnythingToSwiftValueObject(srcDynamicValue, srcDynamicType,
consumeValue);
maybeDeallocateSource(true);
return true;
}
#endif
return _fail(src, srcType, targetType, flags);
};
// If the source type is a value type, it cannot possibly conform
// to a class-bounded protocol.
switch (kind) {
case MetadataKind::ExistentialMetatype:
case MetadataKind::Metatype: {
#if SWIFT_OBJC_INTEROP
// Class metadata can be used as an object when ObjC interop is available.
auto metatypePtr = reinterpret_cast<const Metadata **>(src);
auto metatype = *metatypePtr;
tmp = swift_dynamicCastMetatypeToObjectConditional(metatype);
// If the cast succeeded, use the result value as the class instance
// below.
if (tmp) {
srcDynamicValue = reinterpret_cast<OpaqueValue*>(&tmp);
srcDynamicType = reinterpret_cast<const Metadata*>(tmp);
break;
}
#endif
// Otherwise, metatypes aren't class objects.
return fallbackForNonClass();
}
case MetadataKind::Class:
case MetadataKind::ObjCClassWrapper:
case MetadataKind::ForeignClass:
case MetadataKind::Existential:
// Handle the class cases below. Note that opaque existentials
// shouldn't get here because we should have drilled into them above.
break;
case MetadataKind::Struct:
// If the source type is AnyHashable, cast from that.
if (isAnyHashableType(cast<StructMetadata>(srcDynamicType))) {
bool result =
_dynamicCastFromAnyHashable(dest, srcDynamicValue, srcDynamicType,
targetType, dynamicFlags);
maybeDeallocateSource(result);
return result;
}
LLVM_FALLTHROUGH;
case MetadataKind::Enum:
case MetadataKind::Optional:
#if SWIFT_OBJC_INTEROP
// If the source type is bridged to Objective-C, try to bridge.
if (auto srcBridgeWitness = findBridgeWitness(srcDynamicType)) {
bool success = _dynamicCastValueToClassExistentialViaObjCBridgeable(
dest,
srcDynamicValue,
srcDynamicType,
targetType,
srcBridgeWitness,
dynamicFlags);
maybeDeallocateSource(success);
return success;
}
#endif
LLVM_FALLTHROUGH;
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Opaque:
case MetadataKind::Tuple:
return fallbackForNonClass();
}
// Check for protocol conformances and fill in the witness tables. If
// srcDynamicType equals nullptr we have a cast from an existential
// container with a class instance to AnyObject. In this case no check is
// necessary.
if (srcDynamicType && !_conformsToProtocols(srcDynamicValue, srcDynamicType,
targetType,
destExistential->getWitnessTables()))
return fallbackForNonDirectConformance();
auto object = *(reinterpret_cast<HeapObject**>(srcDynamicValue));
destExistential->Value = object;
if (!canConsumeDynamicValue || !(flags & DynamicCastFlags::TakeOnSuccess)) {
swift_unknownRetain(object);
}
maybeDeallocateSource(true);
return true;
}
case ExistentialTypeRepresentation::Opaque: {
auto destExistential =
reinterpret_cast<OpaqueExistentialContainer*>(dest);
// Check for protocol conformances and fill in the witness tables.
if (!_conformsToProtocols(srcDynamicValue, srcDynamicType,
targetType,
destExistential->getWitnessTables()))
return fallbackForNonDirectConformance();
// Fill in the type and value.
destExistential->Type = srcDynamicType;
if (canConsumeDynamicValue && (flags & DynamicCastFlags::TakeOnSuccess)) {
auto *value = srcDynamicType->allocateBoxForExistentialIn(&destExistential->Buffer);
srcDynamicType->vw_initializeWithTake(value, srcDynamicValue);
} else {
auto *value = srcDynamicType->allocateBoxForExistentialIn(&destExistential->Buffer);
srcDynamicType->vw_initializeWithCopy(value, srcDynamicValue);
}
maybeDeallocateSource(true);
return true;
}
case ExistentialTypeRepresentation::Error: {
auto destBoxAddr =
reinterpret_cast<SwiftError**>(dest);
// Check for the Error protocol conformance, which should be the only
// one we need.
assert(targetType->Protocols.NumProtocols == 1);
const WitnessTable *errorWitness;
if (!_conformsToProtocols(srcDynamicValue, srcDynamicType,
targetType,
&errorWitness))
return fallbackForNonDirectConformance();
#if SWIFT_OBJC_INTEROP
// Check whether there is an embedded NSError. If so, use that for our Error
// representation.
if (auto embedded = getErrorEmbeddedNSErrorIndirect(srcDynamicValue,
srcDynamicType,
errorWitness)) {
*destBoxAddr = reinterpret_cast<SwiftError*>(embedded);
maybeDeallocateSource(true);
return true;
}
#endif
bool isTake =
(canConsumeDynamicValue && (flags & DynamicCastFlags::TakeOnSuccess));
BoxPair destBox = swift_allocError(srcDynamicType, errorWitness,
srcDynamicValue, isTake);
*destBoxAddr = reinterpret_cast<SwiftError*>(destBox.object);
maybeDeallocateSource(true);
return true;
}
}
swift_runtime_unreachable("Unhandled ExistentialTypeRepresentation in switch.");
}
/******************************************************************************/
/********************************** Classes ***********************************/
/******************************************************************************/
static const void *
_dynamicCastUnknownClassToExistential(const void *object,
const ExistentialTypeMetadata *targetType) {
// FIXME: check superclass constraint here.
for (unsigned i = 0, e = targetType->Protocols.NumProtocols; i < e; ++i) {
const ProtocolDescriptor *protocol = targetType->Protocols[i];
switch (protocol->Flags.getDispatchStrategy()) {
case ProtocolDispatchStrategy::Swift:
// If the target existential requires witness tables, we can't do this cast.
// The result type would not have a single-refcounted-pointer rep.
return nullptr;
case ProtocolDispatchStrategy::ObjC:
#if SWIFT_OBJC_INTEROP
if (!objectConformsToObjCProtocol(object, protocol))
return nullptr;
break;
#else
assert(false && "ObjC interop disabled?!");
return nullptr;
#endif
}
}
return object;
}
/// Perform a dynamic class of some sort of class instance to some
/// sort of class type.
const void *
swift::swift_dynamicCastUnknownClass(const void *object,
const Metadata *targetType) {
switch (targetType->getKind()) {
case MetadataKind::Class: {
auto targetClassType = static_cast<const ClassMetadata *>(targetType);
return swift_dynamicCastClass(object, targetClassType);
}
case MetadataKind::ObjCClassWrapper: {
#if SWIFT_OBJC_INTEROP
auto targetClassType
= static_cast<const ObjCClassWrapperMetadata *>(targetType)->Class;
return swift_dynamicCastObjCClass(object, targetClassType);
#else
_failCorruptType(targetType);
#endif
}
case MetadataKind::ForeignClass: {
#if SWIFT_OBJC_INTEROP
auto targetClassType = static_cast<const ForeignClassMetadata*>(targetType);
return swift_dynamicCastForeignClass(object, targetClassType);
#else
_failCorruptType(targetType);
#endif
}
case MetadataKind::Existential: {
return _dynamicCastUnknownClassToExistential(object,
static_cast<const ExistentialTypeMetadata *>(targetType));
}
case MetadataKind::ExistentialMetatype:
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct:
case MetadataKind::Tuple:
return nullptr;
}
_failCorruptType(targetType);
}
/// Perform a dynamic class of some sort of class instance to some
/// sort of class type.
const void *
swift::swift_dynamicCastUnknownClassUnconditional(const void *object,
const Metadata *targetType) {
switch (targetType->getKind()) {
case MetadataKind::Class: {
auto targetClassType = static_cast<const ClassMetadata *>(targetType);
return swift_dynamicCastClassUnconditional(object, targetClassType);
}
case MetadataKind::ObjCClassWrapper: {
#if SWIFT_OBJC_INTEROP
auto targetClassType
= static_cast<const ObjCClassWrapperMetadata *>(targetType)->Class;
return swift_dynamicCastObjCClassUnconditional(object, targetClassType);
#else
_failCorruptType(targetType);
#endif
}
case MetadataKind::ForeignClass: {
#if SWIFT_OBJC_INTEROP
auto targetClassType = static_cast<const ForeignClassMetadata*>(targetType);
return swift_dynamicCastForeignClassUnconditional(object, targetClassType);
#else
_failCorruptType(targetType);
#endif
}
case MetadataKind::Existential: {
// We can cast to ObjC existentials. Non-ObjC existentials don't have
// a single-refcounted-pointer representation.
if (auto result = _dynamicCastUnknownClassToExistential(object,
static_cast<const ExistentialTypeMetadata *>(targetType)))
return result;
swift_dynamicCastFailure(_swift_getClass(object), targetType);
}
case MetadataKind::ExistentialMetatype:
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct:
case MetadataKind::Tuple:
swift_dynamicCastFailure(_swift_getClass(object), targetType);
}
_failCorruptType(targetType);
}
/******************************************************************************/
/********************************* Metatypes **********************************/
/******************************************************************************/
const Metadata *
swift::swift_dynamicCastMetatype(const Metadata *sourceType,
const Metadata *targetType) {
auto origSourceType = sourceType;
switch (targetType->getKind()) {
case MetadataKind::ObjCClassWrapper:
// Get the actual class object.
targetType = static_cast<const ObjCClassWrapperMetadata*>(targetType)
->Class;
LLVM_FALLTHROUGH;
case MetadataKind::Class:
// The source value must also be a class; otherwise the cast fails.
switch (sourceType->getKind()) {
case MetadataKind::ObjCClassWrapper:
// Get the actual class object.
sourceType = static_cast<const ObjCClassWrapperMetadata*>(sourceType)
->Class;
LLVM_FALLTHROUGH;
case MetadataKind::Class: {
// Check if the source is a subclass of the target.
#if SWIFT_OBJC_INTEROP
// We go through ObjC lookup to deal with potential runtime magic in ObjC
// land.
if (swift_dynamicCastObjCClassMetatype((const ClassMetadata*)sourceType,
(const ClassMetadata*)targetType))
return origSourceType;
#else
if (_dynamicCastClassMetatype((const ClassMetadata*)sourceType,
(const ClassMetadata*)targetType))
return origSourceType;
#endif
return nullptr;
}
case MetadataKind::ForeignClass: {
// Check if the source is a subclass of the target.
if (swift_dynamicCastForeignClassMetatype(
(const ClassMetadata*)sourceType,
(const ClassMetadata*)targetType))
return origSourceType;
return nullptr;
}
case MetadataKind::Existential:
case MetadataKind::ExistentialMetatype:
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct:
case MetadataKind::Tuple:
return nullptr;
}
break;
case MetadataKind::ForeignClass:
switch (sourceType->getKind()) {
case MetadataKind::ObjCClassWrapper:
// Get the actual class object.
sourceType = static_cast<const ObjCClassWrapperMetadata*>(sourceType)
->Class;
LLVM_FALLTHROUGH;
case MetadataKind::Class:
case MetadataKind::ForeignClass:
// Check if the source is a subclass of the target.
if (swift_dynamicCastForeignClassMetatype(
(const ClassMetadata*)sourceType,
(const ClassMetadata*)targetType))
return origSourceType;
return nullptr;
case MetadataKind::Existential:
case MetadataKind::ExistentialMetatype:
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct:
case MetadataKind::Tuple:
return nullptr;
}
break;
case MetadataKind::Existential:
case MetadataKind::ExistentialMetatype:
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct:
case MetadataKind::Tuple:
// The cast succeeds only if the metadata pointers are statically
// equivalent.
if (sourceType != targetType)
return nullptr;
return origSourceType;
}
swift_runtime_unreachable("Unhandled MetadataKind in switch.");
}
const Metadata *
swift::swift_dynamicCastMetatypeUnconditional(const Metadata *sourceType,
const Metadata *targetType) {
auto origSourceType = sourceType;
switch (targetType->getKind()) {
case MetadataKind::ObjCClassWrapper:
// Get the actual class object.
targetType = static_cast<const ObjCClassWrapperMetadata*>(targetType)
->Class;
LLVM_FALLTHROUGH;
case MetadataKind::Class:
// The source value must also be a class; otherwise the cast fails.
switch (sourceType->getKind()) {
case MetadataKind::ObjCClassWrapper:
// Get the actual class object.
sourceType = static_cast<const ObjCClassWrapperMetadata*>(sourceType)
->Class;
LLVM_FALLTHROUGH;
case MetadataKind::Class: {
// Check if the source is a subclass of the target.
#if SWIFT_OBJC_INTEROP
// We go through ObjC lookup to deal with potential runtime magic in ObjC
// land.
swift_dynamicCastObjCClassMetatypeUnconditional(
(const ClassMetadata*)sourceType,
(const ClassMetadata*)targetType);
#else
if (!_dynamicCastClassMetatype((const ClassMetadata*)sourceType,
(const ClassMetadata*)targetType))
swift_dynamicCastFailure(sourceType, targetType);
#endif
// If we returned, then the cast succeeded.
return origSourceType;
}
case MetadataKind::ForeignClass: {
// Check if the source is a subclass of the target.
swift_dynamicCastForeignClassMetatypeUnconditional(
(const ClassMetadata*)sourceType,
(const ClassMetadata*)targetType);
// If we returned, then the cast succeeded.
return origSourceType;
}
case MetadataKind::Existential:
case MetadataKind::ExistentialMetatype:
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct:
case MetadataKind::Tuple:
swift_dynamicCastFailure(sourceType, targetType);
}
break;
case MetadataKind::ForeignClass:
// The source value must also be a class; otherwise the cast fails.
switch (sourceType->getKind()) {
case MetadataKind::ObjCClassWrapper:
// Get the actual class object.
sourceType = static_cast<const ObjCClassWrapperMetadata*>(sourceType)
->Class;
LLVM_FALLTHROUGH;
case MetadataKind::Class:
case MetadataKind::ForeignClass:
// Check if the source is a subclass of the target.
swift_dynamicCastForeignClassMetatypeUnconditional(
(const ClassMetadata*)sourceType,
(const ClassMetadata*)targetType);
// If we returned, then the cast succeeded.
return origSourceType;
case MetadataKind::Existential:
case MetadataKind::ExistentialMetatype:
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct:
case MetadataKind::Tuple:
swift_dynamicCastFailure(sourceType, targetType);
}
break;
case MetadataKind::Existential:
case MetadataKind::ExistentialMetatype:
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct:
case MetadataKind::Tuple:
// The cast succeeds only if the metadata pointers are statically
// equivalent.
if (sourceType != targetType)
swift_dynamicCastFailure(sourceType, targetType);
return origSourceType;
}
swift_runtime_unreachable("Unhandled MetadataKind in switch.");
}
/******************************************************************************/
/********************************** Classes ***********************************/
/******************************************************************************/
#if SWIFT_OBJC_INTEROP
/// Do a dynamic cast to the target class.
static void *_dynamicCastUnknownClass(void *object,
const Metadata *targetType,
bool unconditional) {
// The unconditional path avoids some failure logic.
if (unconditional) {
return const_cast<void*>(
swift_dynamicCastUnknownClassUnconditional(object, targetType));
}
return const_cast<void*>(swift_dynamicCastUnknownClass(object, targetType));
}
#endif
static bool _dynamicCastUnknownClassIndirect(OpaqueValue *dest,
void *object,
const Metadata *targetType,
DynamicCastFlags flags) {
void **destSlot = reinterpret_cast<void **>(dest);
// The unconditional path avoids some failure logic.
if (flags & DynamicCastFlags::Unconditional) {
void *result = const_cast<void*>(
swift_dynamicCastUnknownClassUnconditional(object, targetType));
*destSlot = result;
if (!(flags & DynamicCastFlags::TakeOnSuccess)) {
swift_unknownRetain(result);
}
return true;
}
// Okay, we're doing a conditional cast.
void *result =
const_cast<void*>(swift_dynamicCastUnknownClass(object, targetType));
assert(result == nullptr || object == result);
// If the cast failed, destroy the input and return false.
if (!result) {
if (flags & DynamicCastFlags::DestroyOnFailure) {
swift_unknownRelease(object);
}
return false;
}
// Otherwise, store to the destination and return true.
*destSlot = result;
if (!(flags & DynamicCastFlags::TakeOnSuccess)) {
swift_unknownRetain(result);
}
return true;
}
/******************************************************************************/
/******************************** Existentials ********************************/
/******************************************************************************/
#if SWIFT_OBJC_INTEROP
extern "C" const ProtocolDescriptor PROTOCOL_DESCR_SYM(s5Error);
static const WitnessTable *findErrorWitness(const Metadata *srcType) {
return swift_conformsToProtocol(srcType, &PROTOCOL_DESCR_SYM(s5Error));
}
#endif
/// Perform a dynamic cast from an existential type to some kind of
/// class type.
static bool _dynamicCastToUnknownClassFromExistential(OpaqueValue *dest,
OpaqueValue *src,
const ExistentialTypeMetadata *srcType,
const Metadata *targetType,
DynamicCastFlags flags) {
switch (srcType->getRepresentation()) {
case ExistentialTypeRepresentation::Class: {
auto classContainer =
reinterpret_cast<ClassExistentialContainer*>(src);
void *obj = classContainer->Value;
#if SWIFT_OBJC_INTEROP
// If we're casting to NSError, we may need a representation change,
// so fall into the general swift_dynamicCast path.
if (targetType == getNSErrorMetadata()) {
return swift_dynamicCast(dest, src, swift_getObjectType((HeapObject*)obj),
targetType, flags);
}
#endif
return _dynamicCastUnknownClassIndirect(dest, obj, targetType, flags);
}
case ExistentialTypeRepresentation::Opaque: {
auto opaqueContainer =
reinterpret_cast<OpaqueExistentialContainer*>(src);
auto srcCapturedType = opaqueContainer->Type;
OpaqueValue *srcValue = srcType->projectValue(src);
// Can't 'take' out of a non-unique box. So we will force a copy.
auto subFlags = flags;
if (src != srcValue)
subFlags = subFlags - (DynamicCastFlags::DestroyOnFailure
| DynamicCastFlags::TakeOnSuccess);
bool result = swift_dynamicCast(dest, srcValue, srcCapturedType, targetType,
subFlags);
// We were supposed to 'take' the source but we have copied. Reconcile by
// destroying the source.
if (src != srcValue)
if (shouldDeallocateSource(result, flags))
srcType->vw_destroy(src);
return result;
}
case ExistentialTypeRepresentation::Error: {
const SwiftError *errorBox =
*reinterpret_cast<const SwiftError * const *>(src);
auto srcCapturedType = errorBox->getType();
const OpaqueValue *srcValue;
// A bridged NSError is itself the value.
if (errorBox->isPureNSError())
srcValue = src;
else
srcValue = errorBox->getValue();
// We can't take or destroy the value out of the box since it might be
// shared.
auto subFlags = flags - (DynamicCastFlags::TakeOnSuccess
| DynamicCastFlags::DestroyOnFailure);
bool result = swift_dynamicCast(dest,
const_cast<OpaqueValue*>(srcValue),
srcCapturedType, targetType,
subFlags);
if (shouldDeallocateSource(result, flags))
srcType->vw_destroy(src);
return result;
}
}
swift_runtime_unreachable(
"Unhandled ExistentialTypeRepresentation in switch.");
}
static void unwrapExistential(OpaqueValue *src,
const ExistentialTypeMetadata *srcType,
OpaqueValue *&srcValue,
const Metadata *&srcCapturedType,
bool &isOutOfLine,
bool &canTake) {
switch (srcType->getRepresentation()) {
case ExistentialTypeRepresentation::Class: {
auto classContainer =
reinterpret_cast<ClassExistentialContainer*>(src);
srcValue = (OpaqueValue*) &classContainer->Value;
void *obj = classContainer->Value;
srcCapturedType = swift_getObjectType(reinterpret_cast<HeapObject*>(obj));
isOutOfLine = false;
canTake = true;
break;
}
case ExistentialTypeRepresentation::Opaque: {
auto opaqueContainer = reinterpret_cast<OpaqueExistentialContainer*>(src);
srcCapturedType = opaqueContainer->Type;
srcValue = srcType->projectValue(src);
// Can't take out of possibly shared existential boxes.
canTake = (src == srcValue);
assert(canTake == srcCapturedType->getValueWitnesses()->isValueInline() &&
"Only inline storage is take-able");
isOutOfLine = (src != srcValue);
break;
}
case ExistentialTypeRepresentation::Error: {
const SwiftError *errorBox
= *reinterpret_cast<const SwiftError * const *>(src);
srcCapturedType = errorBox->getType();
// A bridged NSError is itself the value.
if (errorBox->isPureNSError())
srcValue = src;
else
srcValue = const_cast<OpaqueValue*>(errorBox->getValue());
// The value is out-of-line, but we can't take it, since it may be shared.
isOutOfLine = true;
canTake = false;
break;
}
}
}
/// Perform a dynamic cast from an existential type to a
/// non-existential type.
static bool _dynamicCastFromExistential(OpaqueValue *dest,
OpaqueValue *src,
const ExistentialTypeMetadata *srcType,
const Metadata *targetType,
DynamicCastFlags flags) {
OpaqueValue *srcValue;
const Metadata *srcCapturedType;
bool isOutOfLine;
bool canTake;
unwrapExistential(src, srcType,
srcValue, srcCapturedType, isOutOfLine, canTake);
auto subFlags = flags;
if (!canTake)
subFlags = subFlags - (DynamicCastFlags::DestroyOnFailure
| DynamicCastFlags::TakeOnSuccess);
bool result = swift_dynamicCast(dest, srcValue, srcCapturedType,
targetType, subFlags);
if (!canTake) {
// swift_dynamicCast performed no memory management.
// Destroy the value if requested.
if (shouldDeallocateSource(result, flags))
srcType->vw_destroy(src);
} else {
assert(!isOutOfLine &&
"Should only see inline representations of existentials");
}
return result;
}
/******************************************************************************/
/********************************* Metatypes **********************************/
/******************************************************************************/
/// Perform a dynamic cast of a metatype to a metatype.
///
/// Note that the check is whether 'metatype' is an *instance of*
/// 'targetType', not a *subtype of it*.
static bool _dynamicCastMetatypeToMetatype(OpaqueValue *dest,
const Metadata *metatype,
const MetatypeMetadata *targetType,
DynamicCastFlags flags) {
const Metadata *result;
if (flags & DynamicCastFlags::Unconditional) {
result = swift_dynamicCastMetatypeUnconditional(metatype,
targetType->InstanceType);
} else {
result = swift_dynamicCastMetatype(metatype, targetType->InstanceType);
if (!result) return false;
}
*((const Metadata **) dest) = result;
return true;
}
/// Check whether an unknown class instance is actually a class object.
static const Metadata *_getUnknownClassAsMetatype(void *object) {
#if SWIFT_OBJC_INTEROP
// Objective-C class metadata are objects, so an AnyObject (or NSObject)
// may refer to a class object.
// Test whether the object's isa is a metaclass, which indicates that the
// object is a class.
Class isa = object_getClass((id)object);
if (class_isMetaClass(isa)) {
return swift_getObjCClassMetadata((const ClassMetadata *)object);
}
#endif
// Class values are currently never metatypes in the native runtime.
return nullptr;
}
/// Perform a dynamic cast of a class value to a metatype type.
static bool _dynamicCastUnknownClassToMetatype(OpaqueValue *dest,
void *object,
const MetatypeMetadata *targetType,
DynamicCastFlags flags) {
if (auto metatype = _getUnknownClassAsMetatype(object))
return _dynamicCastMetatypeToMetatype(dest, metatype, targetType, flags);
if (flags & DynamicCastFlags::Unconditional)
swift_dynamicCastFailure(_swift_getClass(object), targetType);
if (flags & DynamicCastFlags::DestroyOnFailure)
swift_unknownRelease((HeapObject*) object);
return false;
}
/// Perform a dynamic cast to a metatype type.
static bool _dynamicCastToMetatype(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const MetatypeMetadata *targetType,
DynamicCastFlags flags) {
switch (srcType->getKind()) {
case MetadataKind::Metatype: {
const Metadata *srcMetatype = *(const Metadata * const *) src;
return _dynamicCastMetatypeToMetatype(dest, srcMetatype,
targetType, flags);
}
case MetadataKind::ExistentialMetatype: {
const Metadata *srcMetatype = *(const Metadata * const *) src;
return _dynamicCastMetatypeToMetatype(dest, srcMetatype,
targetType, flags);
}
case MetadataKind::Existential: {
auto srcExistentialType = cast<ExistentialTypeMetadata>(srcType);
switch (srcExistentialType->getRepresentation()) {
case ExistentialTypeRepresentation::Class: {
auto srcExistential = (ClassExistentialContainer*) src;
return _dynamicCastUnknownClassToMetatype(dest,
srcExistential->Value,
targetType, flags);
}
case ExistentialTypeRepresentation::Opaque: {
auto srcExistential = (OpaqueExistentialContainer*) src;
auto srcValueType = srcExistential->Type;
// Can't 'take' out of a non-unique box. So we will force a copy.
auto subFlags = flags;
auto srcValue = srcExistentialType->projectValue(src);
if (src != srcValue)
subFlags = subFlags - (DynamicCastFlags::DestroyOnFailure |
DynamicCastFlags::TakeOnSuccess);
bool result = _dynamicCastToMetatype(dest, srcValue, srcValueType,
targetType, subFlags);
// We were supposed to 'take' the source but we have copied. Reconcile by
// destroying the source.
if (src != srcValue)
if (shouldDeallocateSource(result, flags))
srcType->vw_destroy(src);
return result;
}
case ExistentialTypeRepresentation::Error: {
const SwiftError *srcBox
= *reinterpret_cast<const SwiftError * const *>(src);
auto srcValueType = srcBox->getType();
const OpaqueValue *srcValue;
if (srcBox->isPureNSError())
srcValue = src;
else
srcValue = srcBox->getValue();
// Can't take from a box since the value may be shared.
auto subFlags = flags - (DynamicCastFlags::TakeOnSuccess
| DynamicCastFlags::DestroyOnFailure);
bool result = _dynamicCastToMetatype(dest,
const_cast<OpaqueValue*>(srcValue),
srcValueType,
targetType, subFlags);
if (shouldDeallocateSource(result, flags))
srcType->vw_destroy(src);
return result;
}
}
}
case MetadataKind::Class:
case MetadataKind::ObjCClassWrapper:
case MetadataKind::ForeignClass: {
void *object = *reinterpret_cast<void**>(src);
return _dynamicCastUnknownClassToMetatype(dest, object, targetType, flags);
}
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct: // AnyHashable, if metatypes implement Hashable
case MetadataKind::Tuple:
return _fail(src, srcType, targetType, flags);
}
_failCorruptType(srcType);
}
/// Perform a dynamic cast of a metatype to an existential metatype type.
static bool _dynamicCastMetatypeToExistentialMetatype(OpaqueValue *dest,
const Metadata *srcMetatype,
const ExistentialMetatypeMetadata *targetType,
DynamicCastFlags flags,
bool writeDestMetatype = true) {
// The instance type of an existential metatype must be either an
// existential or an existential metatype.
auto destMetatype = reinterpret_cast<ExistentialMetatypeContainer*>(dest);
// If it's an existential, we need to check for conformances.
auto targetInstanceType = targetType->InstanceType;
if (auto targetInstanceTypeAsExistential =
dyn_cast<ExistentialTypeMetadata>(targetInstanceType)) {
// Check for conformance to all the protocols.
// TODO: collect the witness tables.
const WitnessTable **conformance
= writeDestMetatype ? destMetatype->getWitnessTables() : nullptr;
if (!_conformsToProtocols(nullptr, srcMetatype,
targetInstanceTypeAsExistential,
conformance)) {
if (flags & DynamicCastFlags::Unconditional)
swift_dynamicCastFailure(srcMetatype, targetType);
return false;
}
if (writeDestMetatype)
destMetatype->Value = srcMetatype;
return true;
}
// Otherwise, we're casting to SomeProtocol.Type.Type.
auto targetInstanceTypeAsMetatype =
cast<ExistentialMetatypeMetadata>(targetInstanceType);
// If the source type isn't a metatype, the cast fails.
auto srcMetatypeMetatype = dyn_cast<MetatypeMetadata>(srcMetatype);
if (!srcMetatypeMetatype) {
if (flags & DynamicCastFlags::Unconditional)
swift_dynamicCastFailure(srcMetatype, targetType);
return false;
}
// The representation of an existential metatype remains consistent
// arbitrarily deep: a metatype, followed by some protocols. The
// protocols are the same at every level, so we can just set the
// metatype correctly and then recurse, letting the recursive call
// fill in the conformance information correctly.
// Proactively set the destination metatype so that we can tail-recur,
// unless we've already done so. There's no harm in doing this even if
// the cast fails.
if (writeDestMetatype)
*((const Metadata **) dest) = srcMetatype;
// Recurse.
auto srcInstanceType = srcMetatypeMetatype->InstanceType;
return _dynamicCastMetatypeToExistentialMetatype(dest, srcInstanceType,
targetInstanceTypeAsMetatype,
flags,
/*overwrite*/ false);
}
/// Perform a dynamic cast of a class value to an existential metatype type.
static bool _dynamicCastUnknownClassToExistentialMetatype(OpaqueValue *dest,
void *object,
const ExistentialMetatypeMetadata *targetType,
DynamicCastFlags flags) {
if (auto metatype = _getUnknownClassAsMetatype(object))
return _dynamicCastMetatypeToExistentialMetatype(dest, metatype,
targetType, flags);
// Class values are currently never metatypes (?).
if (flags & DynamicCastFlags::Unconditional)
swift_dynamicCastFailure(_swift_getClass(object), targetType);
if (flags & DynamicCastFlags::DestroyOnFailure)
swift_unknownRelease((HeapObject*) object);
return false;
}
/// Perform a dynamic cast to an existential metatype type.
static bool _dynamicCastToExistentialMetatype(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const ExistentialMetatypeMetadata *targetType,
DynamicCastFlags flags) {
switch (srcType->getKind()) {
case MetadataKind::Metatype: {
const Metadata *srcMetatype = *(const Metadata * const *) src;
return _dynamicCastMetatypeToExistentialMetatype(dest, srcMetatype,
targetType, flags);
}
// TODO: take advantage of protocol conformances already known.
case MetadataKind::ExistentialMetatype: {
const Metadata *srcMetatype = *(const Metadata * const *) src;
return _dynamicCastMetatypeToExistentialMetatype(dest, srcMetatype,
targetType, flags);
}
case MetadataKind::Existential: {
auto srcExistentialType = cast<ExistentialTypeMetadata>(srcType);
switch (srcExistentialType->getRepresentation()) {
case ExistentialTypeRepresentation::Class: {
auto srcExistential = (ClassExistentialContainer*) src;
return _dynamicCastUnknownClassToExistentialMetatype(dest,
srcExistential->Value,
targetType, flags);
}
case ExistentialTypeRepresentation::Opaque: {
auto srcExistential = (OpaqueExistentialContainer*) src;
auto srcValueType = srcExistential->Type;
auto subFlags = flags;
auto srcValue = srcExistentialType->projectValue(src);
// Can't 'take' out of a non-unique box. So we will force a copy.
if (src != srcValue)
subFlags = subFlags - (DynamicCastFlags::DestroyOnFailure |
DynamicCastFlags::TakeOnSuccess);
bool result = _dynamicCastToExistentialMetatype(
dest, srcValue, srcValueType, targetType, subFlags);
// We were supposed to 'take' the source but we have copied. Reconcile by
// destroying the source.
if (src != srcValue)
if (shouldDeallocateSource(result, flags))
srcType->vw_destroy(src);
return result;
}
case ExistentialTypeRepresentation::Error: {
const SwiftError *srcBox
= *reinterpret_cast<const SwiftError * const *>(src);
auto srcValueType = srcBox->getType();
const OpaqueValue *srcValue;
if (srcBox->isPureNSError())
srcValue = src;
else
srcValue = srcBox->getValue();
// Can't take from a box since the value may be shared.
auto subFlags = flags - (DynamicCastFlags::TakeOnSuccess
| DynamicCastFlags::DestroyOnFailure);
bool result = _dynamicCastToExistentialMetatype(dest,
const_cast<OpaqueValue*>(srcValue),
srcValueType,
targetType, subFlags);
if (shouldDeallocateSource(result, flags))
srcType->vw_destroy(src);
return result;
}
}
}
case MetadataKind::Class:
case MetadataKind::ObjCClassWrapper:
case MetadataKind::ForeignClass: {
void *object = *reinterpret_cast<void**>(src);
return _dynamicCastUnknownClassToExistentialMetatype(dest, object,
targetType, flags);
}
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Struct: // AnyHashable, if metatypes implement Hashable
case MetadataKind::Tuple:
return _fail(src, srcType, targetType, flags);
}
_failCorruptType(srcType);
}
/******************************************************************************/
/********************************* Functions **********************************/
/******************************************************************************/
static bool _dynamicCastToFunction(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const FunctionTypeMetadata *targetType,
DynamicCastFlags flags) {
// Function casts succeed on exact matches, or if the target type is
// throwier than the source type.
//
// TODO: We could also allow ABI-compatible variance, such as casting
// a dynamic Base -> Derived to Derived -> Base. We wouldn't be able to
// perform a dynamic cast that required any ABI adjustment without a JIT
// though.
// Check for an exact type match first.
if (srcType == targetType) {
return _succeed(dest, src, srcType, flags);
}
switch (srcType->getKind()) {
case MetadataKind::Function: {
auto srcFn = static_cast<const FunctionTypeMetadata *>(srcType);
auto targetFn = static_cast<const FunctionTypeMetadata *>(targetType);
// Check that argument counts and convention match. "throws" can vary.
if (srcFn->Flags.withThrows(false) != targetFn->Flags.withThrows(false))
return _fail(src, srcType, targetType, flags);
// If the target type can't throw, neither can the source.
if (srcFn->throws() && !targetFn->throws())
return _fail(src, srcType, targetType, flags);
// The result and argument types must match.
if (srcFn->ResultType != targetFn->ResultType)
return _fail(src, srcType, targetType, flags);
if (srcFn->getNumParameters() != targetFn->getNumParameters())
return _fail(src, srcType, targetType, flags);
if (srcFn->hasParameterFlags() != targetFn->hasParameterFlags())
return _fail(src, srcType, targetType, flags);
for (unsigned i = 0, e = srcFn->getNumParameters(); i < e; ++i) {
if (srcFn->getParameter(i) != targetFn->getParameter(i) ||
srcFn->getParameterFlags(i) != targetFn->getParameterFlags(i))
return _fail(src, srcType, targetType, flags);
}
return _succeed(dest, src, srcType, flags);
}
case MetadataKind::Existential:
return _dynamicCastFromExistential(dest, src,
static_cast<const ExistentialTypeMetadata*>(srcType),
targetType, flags);
case MetadataKind::Class:
case MetadataKind::Struct:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::ObjCClassWrapper:
case MetadataKind::ForeignClass:
case MetadataKind::ExistentialMetatype:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Opaque:
case MetadataKind::Tuple:
return _fail(src, srcType, targetType, flags);
}
swift_runtime_unreachable("Unhandled MetadataKind in switch.");
}
/******************************************************************************/
/****************************** Bridging NSError ******************************/
/******************************************************************************/
#if SWIFT_OBJC_INTEROP
static id dynamicCastValueToNSError(OpaqueValue *src,
const Metadata *srcType,
const WitnessTable *srcErrorWitness,
DynamicCastFlags flags) {
// Check whether there is an embedded NSError.
if (auto embedded = getErrorEmbeddedNSErrorIndirect(src, srcType,
srcErrorWitness)) {
if (flags & DynamicCastFlags::TakeOnSuccess)
srcType->vw_destroy(src);
return embedded;
}
BoxPair errorBox = swift_allocError(srcType, srcErrorWitness, src,
/*isTake*/ flags & DynamicCastFlags::TakeOnSuccess);
return _swift_stdlib_bridgeErrorToNSError((SwiftError*)errorBox.object);
}
#endif
/******************************************************************************/
/********************************* Optionals **********************************/
/******************************************************************************/
namespace {
struct OptionalCastResult {
bool success;
const Metadata* payloadType;
};
} // end anonymous namespace
/// Handle optional unwrapping of the cast source.
/// \returns {true, nullptr} if the cast succeeds without unwrapping.
/// \returns {false, nullptr} if the cast fails before unwrapping.
/// \returns {false, payloadType} if the cast should be attempted using an
/// equivalent payloadType.
static OptionalCastResult
checkDynamicCastFromOptional(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const Metadata *targetType,
DynamicCastFlags flags) {
if (srcType->getKind() != MetadataKind::Optional)
return {false, srcType};
// Check if the target is an existential that Optional always conforms to.
if (targetType->getKind() == MetadataKind::Existential) {
// Attempt a conditional cast without destroying on failure.
DynamicCastFlags checkCastFlags
= flags - (DynamicCastFlags::Unconditional
| DynamicCastFlags::DestroyOnFailure);
assert((checkCastFlags - DynamicCastFlags::TakeOnSuccess)
== DynamicCastFlags::Default && "Unhandled DynamicCastFlag");
if (_dynamicCastToExistential(dest, src, srcType,
cast<ExistentialTypeMetadata>(targetType),
checkCastFlags)) {
return {true, nullptr};
}
}
const Metadata *payloadType =
cast<EnumMetadata>(srcType)->getGenericArgs()[0];
int enumCase =
swift_getEnumCaseSinglePayload(src, payloadType, 1 /*emptyCases=*/);
if (enumCase != -1) {
// Allow Optional<T>.none -> Optional<U>.none
if (targetType->getKind() != MetadataKind::Optional) {
_fail(src, srcType, targetType, flags);
return {false, nullptr};
}
// Get the destination payload type
const Metadata *targetPayloadType =
cast<EnumMetadata>(targetType)->getGenericArgs()[0];
// Inject the .none tag
swift_storeEnumTagSinglePayload(dest, targetPayloadType, enumCase,
1 /*emptyCases=*/);
// We don't have to destroy the source, because it was nil.
return {true, nullptr};
}
// .Some
// Single payload enums are guaranteed layout compatible with their
// payload. Only the source's payload needs to be taken or destroyed.
return {false, payloadType};
}
/******************************************************************************/
/**************************** Bridging _SwiftValue ****************************/
/******************************************************************************/
#if SWIFT_OBJC_INTEROP
/// Try to unbox a _SwiftValue box to perform a dynamic cast.
static bool tryDynamicCastBoxedSwiftValue(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const Metadata *targetType,
DynamicCastFlags flags) {
// These flag combinations are not handled here.
assert(!(flags & DynamicCastFlags::Unconditional));
assert(!(flags & DynamicCastFlags::DestroyOnFailure));
// Swift type should be AnyObject or a class type.
if (!srcType->isAnyClass()) {
auto existential = dyn_cast<ExistentialTypeMetadata>(srcType);
if (!existential || !isAnyObjectExistentialType(existential))
return false;
}
id srcObject;
memcpy(&srcObject, src, sizeof(id));
// Do we have a _SwiftValue?
_SwiftValue *srcSwiftValue = getAsSwiftValue(srcObject);
if (!srcSwiftValue)
return false;
// If so, extract the boxed value and try to cast it.
const Metadata *boxedType;
const OpaqueValue *boxedValue;
std::tie(boxedType, boxedValue)
= getValueFromSwiftValue(srcSwiftValue);
// We can't touch the value from the box because it may be
// multiply-referenced.
// TODO: Check for uniqueness and consume if box is unique?
// Does the boxed type exactly match the target type we're looking for?
if (boxedType == targetType) {
targetType->vw_initializeWithCopy(dest,
const_cast<OpaqueValue*>(boxedValue));
// Release the box if we need to.
if (flags & DynamicCastFlags::TakeOnSuccess)
objc_release((id)srcSwiftValue);
return true;
}
// Maybe we can cast the boxed value to our destination type somehow.
auto innerFlags = flags - DynamicCastFlags::TakeOnSuccess
- DynamicCastFlags::DestroyOnFailure
- DynamicCastFlags::Unconditional;
if (swift_dynamicCast(dest, const_cast<OpaqueValue*>(boxedValue),
boxedType, targetType, innerFlags)) {
// Release the box if we need to.
if (flags & DynamicCastFlags::TakeOnSuccess)
objc_release((id)srcSwiftValue);
return true;
}
return false;
}
#endif
/******************************************************************************/
/******************************** Collections *********************************/
/******************************************************************************/
/// Nominal type descriptor for Swift.Array.
extern "C" const StructDescriptor NOMINAL_TYPE_DESCR_SYM(Sa);
/// Nominal type descriptor for Swift.Dictionary.
extern "C" const StructDescriptor STRUCT_TYPE_DESCR_SYM(s10Dictionary);
/// Nominal type descriptor for Swift.Set.
extern "C" const StructDescriptor STRUCT_TYPE_DESCR_SYM(s3Set);
// internal func _arrayDownCastIndirect<SourceValue, TargetValue>(
// _ source: UnsafePointer<Array<SourceValue>>,
// _ target: UnsafeMutablePointer<Array<TargetValue>>)
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
void _swift_arrayDownCastIndirect(OpaqueValue *destination,
OpaqueValue *source,
const Metadata *sourceValueType,
const Metadata *targetValueType);
// internal func _arrayDownCastConditionalIndirect<SourceValue, TargetValue>(
// _ source: UnsafePointer<Array<SourceValue>>,
// _ target: UnsafeMutablePointer<Array<TargetValue>>
// ) -> Bool
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
bool _swift_arrayDownCastConditionalIndirect(OpaqueValue *destination,
OpaqueValue *source,
const Metadata *sourceValueType,
const Metadata *targetValueType);
// internal func _setDownCastIndirect<SourceValue, TargetValue>(
// _ source: UnsafePointer<Set<SourceValue>>,
// _ target: UnsafeMutablePointer<Set<TargetValue>>)
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
void _swift_setDownCastIndirect(OpaqueValue *destination,
OpaqueValue *source,
const Metadata *sourceValueType,
const Metadata *targetValueType,
const void *sourceValueHashable,
const void *targetValueHashable);
// internal func _setDownCastConditionalIndirect<SourceValue, TargetValue>(
// _ source: UnsafePointer<Set<SourceValue>>,
// _ target: UnsafeMutablePointer<Set<TargetValue>>
// ) -> Bool
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
bool _swift_setDownCastConditionalIndirect(OpaqueValue *destination,
OpaqueValue *source,
const Metadata *sourceValueType,
const Metadata *targetValueType,
const void *sourceValueHashable,
const void *targetValueHashable);
// internal func _dictionaryDownCastIndirect<SourceKey, SourceValue,
// TargetKey, TargetValue>(
// _ source: UnsafePointer<Dictionary<SourceKey, SourceValue>>,
// _ target: UnsafeMutablePointer<Dictionary<TargetKey, TargetValue>>)
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
void _swift_dictionaryDownCastIndirect(OpaqueValue *destination,
OpaqueValue *source,
const Metadata *sourceKeyType,
const Metadata *sourceValueType,
const Metadata *targetKeyType,
const Metadata *targetValueType,
const void *sourceKeyHashable,
const void *targetKeyHashable);
// internal func _dictionaryDownCastConditionalIndirect<SourceKey, SourceValue,
// TargetKey, TargetValue>(
// _ source: UnsafePointer<Dictionary<SourceKey, SourceValue>>,
// _ target: UnsafeMutablePointer<Dictionary<TargetKey, TargetValue>>
// ) -> Bool
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
bool _swift_dictionaryDownCastConditionalIndirect(OpaqueValue *destination,
OpaqueValue *source,
const Metadata *sourceKeyType,
const Metadata *sourceValueType,
const Metadata *targetKeyType,
const Metadata *targetValueType,
const void *sourceKeyHashable,
const void *targetKeyHashable);
static bool _dynamicCastStructToStruct(OpaqueValue *destination,
OpaqueValue *source,
const StructMetadata *sourceType,
const StructMetadata *targetType,
DynamicCastFlags flags) {
if (sourceType == targetType)
return _succeed(destination, source, sourceType, flags);
// The two types have to be instantiations of the same type.
const auto descriptor = sourceType->Description;
const auto targetDescriptor = targetType->Description;
if (descriptor != targetDescriptor) {
if (descriptor == &STRUCT_TYPE_DESCR_SYM(s11AnyHashable)) {
return _dynamicCastFromAnyHashable(destination, source,
sourceType, targetType, flags);
} else if (targetDescriptor == &STRUCT_TYPE_DESCR_SYM(s11AnyHashable)) {
return _dynamicCastToAnyHashable(destination, source,
sourceType, targetType, flags);
} else {
return _fail(source, sourceType, targetType, flags);
}
}
auto sourceArgs = sourceType->getGenericArgs();
auto targetArgs = targetType->getGenericArgs();
bool result;
// Arrays.
if (descriptor == &NOMINAL_TYPE_DESCR_SYM(Sa)) {
if (flags & DynamicCastFlags::Unconditional) {
_swift_arrayDownCastIndirect(source, destination,
sourceArgs[0], targetArgs[0]);
result = true;
} else {
result =
_swift_arrayDownCastConditionalIndirect(source, destination,
sourceArgs[0], targetArgs[0]);
}
// Dictionaries.
} else if (descriptor == &STRUCT_TYPE_DESCR_SYM(s10Dictionary)) {
if (flags & DynamicCastFlags::Unconditional) {
_swift_dictionaryDownCastIndirect(source, destination,
sourceArgs[0], sourceArgs[1],
targetArgs[0], targetArgs[1],
sourceArgs[2], targetArgs[2]);
result = true;
} else {
result =
_swift_dictionaryDownCastConditionalIndirect(source, destination,
sourceArgs[0], sourceArgs[1],
targetArgs[0], targetArgs[1],
sourceArgs[2], targetArgs[2]);
}
// Sets.
} else if (descriptor == &STRUCT_TYPE_DESCR_SYM(s3Set)) {
if (flags & DynamicCastFlags::Unconditional) {
_swift_setDownCastIndirect(source, destination,
sourceArgs[0], targetArgs[0],
sourceArgs[1], targetArgs[1]);
result = true;
} else {
result =
_swift_setDownCastConditionalIndirect(source, destination,
sourceArgs[0], targetArgs[0],
sourceArgs[1], targetArgs[1]);
}
// Other struct types don't support dynamic covariance for now.
} else {
return _fail(source, sourceType, targetType, flags);
}
// The intrinsics above never consume the source value.
bool shouldDestroySource =
result ? flags & DynamicCastFlags::TakeOnSuccess
: flags & DynamicCastFlags::DestroyOnFailure;
if (shouldDestroySource) {
sourceType->vw_destroy(source);
}
return result;
}
static bool _dynamicCastTupleToTuple(OpaqueValue *destination,
OpaqueValue *source,
const TupleTypeMetadata *sourceType,
const TupleTypeMetadata *targetType,
DynamicCastFlags flags) {
assert(sourceType != targetType &&
"Caller should handle exact tuple matches");
// Simple case: number of elements mismatches.
if (sourceType->NumElements != targetType->NumElements)
return _fail(source, sourceType, targetType, flags);
// Check that the elements line up.
const char *sourceLabels = sourceType->Labels;
const char *targetLabels = targetType->Labels;
bool anyTypeMismatches = false;
for (unsigned i = 0, n = sourceType->NumElements; i != n; ++i) {
// Check the label, if there is one.
if (sourceLabels && targetLabels && sourceLabels != targetLabels) {
const char *sourceSpace = strchr(sourceLabels, ' ');
const char *targetSpace = strchr(targetLabels, ' ');
// If both have labels, and the labels mismatch, we fail.
if (sourceSpace && sourceSpace != sourceLabels &&
targetSpace && targetSpace != targetLabels) {
unsigned sourceLen = sourceSpace - sourceLabels;
unsigned targetLen = targetSpace - targetLabels;
if (sourceLen != targetLen ||
strncmp(sourceLabels, targetLabels, sourceLen) != 0)
return _fail(source, sourceType, targetType, flags);
}
sourceLabels = sourceSpace ? sourceSpace + 1 : nullptr;
targetLabels = targetSpace ? targetSpace + 1 : nullptr;
}
// If the types don't match exactly, make a note of it. We'll try to
// convert them in a second pass.
if (sourceType->getElement(i).Type != targetType->getElement(i).Type)
anyTypeMismatches = true;
}
// If there were no type mismatches, the only difference was in the argument
// labels. We can directly map from the source to the destination type.
if (!anyTypeMismatches)
return _succeed(destination, source, targetType, flags);
// Determine how the individual elements will get casted.
// If both success and failure will destroy the source, then
// we can be destructively cast each element. Otherwise, we'll have to
// manually handle them.
const DynamicCastFlags alwaysDestroySourceFlags =
DynamicCastFlags::TakeOnSuccess | DynamicCastFlags::DestroyOnFailure;
bool alwaysDestroysSource =
(static_cast<DynamicCastFlags>(flags & alwaysDestroySourceFlags)
== alwaysDestroySourceFlags);
DynamicCastFlags elementFlags = flags;
if (!alwaysDestroysSource)
elementFlags = elementFlags - alwaysDestroySourceFlags;
// Local function to destroy the elements in the range [start, end).
auto destroyRange = [](const TupleTypeMetadata *type, OpaqueValue *value,
unsigned start, unsigned end) {
assert(start <= end && "invalid range in destroyRange");
for (unsigned i = start; i != end; ++i) {
const auto &elt = type->getElement(i);
elt.Type->vw_destroy(elt.findIn(value));
}
};
// Cast each element.
for (unsigned i = 0, n = sourceType->NumElements; i != n; ++i) {
// Cast the element. If it succeeds, keep going.
const auto &sourceElt = sourceType->getElement(i);
const auto &targetElt = targetType->getElement(i);
if (swift_dynamicCast(targetElt.findIn(destination),
sourceElt.findIn(source),
sourceElt.Type, targetElt.Type, elementFlags))
continue;
// Casting failed, so clean up.
// Destroy all of the elements that got casted into the destination buffer.
destroyRange(targetType, destination, 0, i);
// If we're supposed to destroy on failure, destroy any elements from the
// source buffer that haven't been destroyed/taken from yet.
if (flags & DynamicCastFlags::DestroyOnFailure)
destroyRange(sourceType, source, alwaysDestroysSource ? i : 0, n);
// If an unconditional cast failed, complain.
if (flags & DynamicCastFlags::Unconditional)
swift_dynamicCastFailure(sourceType, targetType);
return false;
}
// Casting succeeded.
// If we were supposed to take on success from the source buffer but couldn't
// before, destroy the source buffer now.
if (!alwaysDestroysSource && (flags & DynamicCastFlags::TakeOnSuccess))
destroyRange(sourceType, source, 0, sourceType->NumElements);
return true;
}
/******************************************************************************/
/****************************** Main Entrypoint *******************************/
/******************************************************************************/
/// Perform a dynamic cast to an arbitrary type.
bool swift::swift_dynamicCast(OpaqueValue *dest, OpaqueValue *src,
const Metadata *srcType,
const Metadata *targetType,
DynamicCastFlags flags) {
auto unwrapResult = checkDynamicCastFromOptional(dest, src, srcType,
targetType, flags);
srcType = unwrapResult.payloadType;
if (!srcType)
return unwrapResult.success;
#if SWIFT_OBJC_INTEROP
// A class or AnyObject reference may point to a _SwiftValue box.
{
auto innerFlags = flags - DynamicCastFlags::Unconditional
- DynamicCastFlags::DestroyOnFailure;
if (tryDynamicCastBoxedSwiftValue(dest, src, srcType,
targetType, innerFlags)) {
// TakeOnSuccess was handled inside tryDynamicCastBoxedSwiftValue().
return true;
} else {
// Couldn't cast boxed value to targetType.
// Fall through and try to cast the _SwiftValue box itself to targetType.
// (for example, casting _SwiftValue to NSObject will be successful)
}
}
#endif
switch (targetType->getKind()) {
// Handle wrapping an Optional target.
case MetadataKind::Optional: {
// If the source is an existential, attempt to cast it first without
// unwrapping the target. This handles an optional source wrapped within an
// existential that Optional conforms to (Any).
if (auto srcExistentialType = dyn_cast<ExistentialTypeMetadata>(srcType)) {
#if SWIFT_OBJC_INTEROP
// If coming from AnyObject, we may want to bridge.
if (isAnyObjectExistentialType(srcExistentialType)) {
if (auto targetBridgeWitness = findBridgeWitness(targetType)) {
return _dynamicCastClassToValueViaObjCBridgeable(dest, src, srcType,
targetType,
targetBridgeWitness,
flags);
}
}
#endif
return _dynamicCastFromExistential(dest, src, srcExistentialType,
targetType, flags);
}
// Recursively cast into the layout compatible payload area.
const Metadata *payloadType =
cast<EnumMetadata>(targetType)->getGenericArgs()[0];
if (swift_dynamicCast(dest, src, srcType, payloadType, flags)) {
swift_storeEnumTagSinglePayload(dest, payloadType, -1 /*case*/,
1 /*emptyCases*/);
return true;
}
return false;
}
// Casts to class type.
case MetadataKind::Class:
case MetadataKind::ObjCClassWrapper:
#if SWIFT_OBJC_INTEROP
// If the destination type is an NSError, and the source type is an
// Error, then the cast can succeed by NSError bridging.
if (targetType == getNSErrorMetadata()) {
// Don't rebridge if the source is already some kind of NSError.
if (srcType->isAnyClass()
&& swift_dynamicCastObjCClass(*reinterpret_cast<id*>(src),
static_cast<const ObjCClassWrapperMetadata*>(targetType)->Class))
return _succeed(dest, src, srcType, flags);
if (auto srcErrorWitness = findErrorWitness(srcType)) {
auto error = dynamicCastValueToNSError(src, srcType,
srcErrorWitness, flags);
*reinterpret_cast<id *>(dest) = error;
return true;
}
}
LLVM_FALLTHROUGH;
#endif
case MetadataKind::ForeignClass:
switch (srcType->getKind()) {
case MetadataKind::Class:
case MetadataKind::ObjCClassWrapper:
case MetadataKind::ForeignClass: {
// Do a dynamic cast on the instance pointer.
void *object = *reinterpret_cast<void * const *>(src);
return _dynamicCastUnknownClassIndirect(dest, object,
targetType, flags);
}
case MetadataKind::Existential: {
auto srcExistentialType = cast<ExistentialTypeMetadata>(srcType);
return _dynamicCastToUnknownClassFromExistential(dest, src,
srcExistentialType,
targetType, flags);
}
case MetadataKind::Struct:
// If the source type is AnyHashable, cast from that.
if (isAnyHashableType(cast<StructMetadata>(srcType))) {
return _dynamicCastFromAnyHashable(dest, src, srcType,
targetType, flags);
}
LLVM_FALLTHROUGH;
case MetadataKind::Enum:
case MetadataKind::Optional: {
#if SWIFT_OBJC_INTEROP
// If the source type is bridged to Objective-C, try to bridge.
if (auto srcBridgeWitness = findBridgeWitness(srcType)) {
return _dynamicCastValueToClassViaObjCBridgeable(dest, src, srcType,
targetType,
srcBridgeWitness,
flags);
}
#endif
return _fail(src, srcType, targetType, flags);
}
case MetadataKind::ExistentialMetatype:
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Opaque:
case MetadataKind::Tuple:
return _fail(src, srcType, targetType, flags);
}
break;
case MetadataKind::Existential:
return _dynamicCastToExistential(dest, src, srcType,
cast<ExistentialTypeMetadata>(targetType),
flags);
case MetadataKind::Metatype:
return _dynamicCastToMetatype(dest, src, srcType,
cast<MetatypeMetadata>(targetType),
flags);
case MetadataKind::ExistentialMetatype:
return _dynamicCastToExistentialMetatype(dest, src, srcType,
cast<ExistentialMetatypeMetadata>(targetType),
flags);
// Function types.
case MetadataKind::Function: {
return _dynamicCastToFunction(dest, src, srcType,
cast<FunctionTypeMetadata>(targetType),
flags);
}
case MetadataKind::Struct:
case MetadataKind::Enum:
switch (srcType->getKind()) {
case MetadataKind::Class:
case MetadataKind::ObjCClassWrapper:
case MetadataKind::ForeignClass: {
// Casts to AnyHashable.
if (isAnyHashableType(targetType)) {
return _dynamicCastToAnyHashable(dest, src, srcType, targetType, flags);
}
#if SWIFT_OBJC_INTEROP
// If the target type is bridged to Objective-C, try to bridge.
if (auto targetBridgeWitness = findBridgeWitness(targetType)) {
return _dynamicCastClassToValueViaObjCBridgeable(dest, src, srcType,
targetType,
targetBridgeWitness,
flags);
}
// If the source is an NSError, and the target is a bridgeable
// Error, try to bridge.
if (tryDynamicCastNSErrorToValue(dest, src, srcType, targetType, flags)) {
return true;
}
#endif
break;
}
case MetadataKind::Struct:
// Collection and AnyHashable casts.
if (targetType->getKind() == MetadataKind::Struct) {
return _dynamicCastStructToStruct(dest, src,
cast<StructMetadata>(srcType),
cast<StructMetadata>(targetType),
flags);
}
break;
case MetadataKind::Optional:
case MetadataKind::Enum:
// Casts to AnyHashable.
if (isAnyHashableType(targetType)) {
return _dynamicCastToAnyHashable(dest, src, srcType, targetType, flags);
}
break;
case MetadataKind::Existential:
case MetadataKind::ExistentialMetatype:
case MetadataKind::Function:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Metatype:
case MetadataKind::Opaque:
case MetadataKind::Tuple:
break;
}
LLVM_FALLTHROUGH;
// The non-polymorphic types.
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
case MetadataKind::Opaque:
case MetadataKind::Tuple:
// If there's an exact type match, we're done.
if (srcType == targetType)
return _succeed(dest, src, srcType, flags);
// If we have an existential, look at its dynamic type.
if (auto srcExistentialType = dyn_cast<ExistentialTypeMetadata>(srcType)) {
return _dynamicCastFromExistential(dest, src, srcExistentialType,
targetType, flags);
}
// If both are tuple types, allow the cast to add/remove labels.
if (srcType->getKind() == MetadataKind::Tuple &&
targetType->getKind() == MetadataKind::Tuple) {
return _dynamicCastTupleToTuple(dest, src,
cast<TupleTypeMetadata>(srcType),
cast<TupleTypeMetadata>(targetType),
flags);
}
// Otherwise, we have a failure.
return _fail(src, srcType, targetType, flags);
}
_failCorruptType(srcType);
}
static inline bool swift_isClassOrObjCExistentialTypeImpl(const Metadata *T) {
auto kind = T->getKind();
// Classes.
if (Metadata::isAnyKindOfClass(kind))
return true;
#if SWIFT_OBJC_INTEROP
// ObjC existentials.
if (kind == MetadataKind::Existential &&
static_cast<const ExistentialTypeMetadata *>(T)->isObjC())
return true;
// Blocks are ObjC objects.
if (kind == MetadataKind::Function) {
auto fT = static_cast<const FunctionTypeMetadata *>(T);
return fT->getConvention() == FunctionMetadataConvention::Block;
}
#endif
return false;
}
/******************************************************************************/
/********************************** Bridging **********************************/
/******************************************************************************/
#if SWIFT_OBJC_INTEROP
//===----------------------------------------------------------------------===//
// Bridging to and from Objective-C
//===----------------------------------------------------------------------===//
namespace {
// protocol _ObjectiveCBridgeable {
struct _ObjectiveCBridgeableWitnessTable {
/// The protocol conformance descriptor.
const void *protocolConformanceDescriptor;
static_assert(WitnessTableFirstRequirementOffset == 1,
"Witness table layout changed");
// associatedtype _ObjectiveCType : class
const Metadata * (*ObjectiveCType)(
const Metadata *parentMetadata,
const _ObjectiveCBridgeableWitnessTable *witnessTable);
// func _bridgeToObjectiveC() -> _ObjectiveCType
SWIFT_CC(swift)
HeapObject *(*bridgeToObjectiveC)(
SWIFT_CONTEXT OpaqueValue *self, const Metadata *Self,
const _ObjectiveCBridgeableWitnessTable *witnessTable);
// class func _forceBridgeFromObjectiveC(x: _ObjectiveCType,
// inout result: Self?)
SWIFT_CC(swift)
void (*forceBridgeFromObjectiveC)(
HeapObject *sourceValue,
OpaqueValue *result,
SWIFT_CONTEXT const Metadata *self,
const Metadata *selfType,
const _ObjectiveCBridgeableWitnessTable *witnessTable);
// class func _conditionallyBridgeFromObjectiveC(x: _ObjectiveCType,
// inout result: Self?) -> Bool
SWIFT_CC(swift)
bool (*conditionallyBridgeFromObjectiveC)(
HeapObject *sourceValue,
OpaqueValue *result,
SWIFT_CONTEXT const Metadata *self,
const Metadata *selfType,
const _ObjectiveCBridgeableWitnessTable *witnessTable);
};
// }
} // unnamed namespace
extern "C" const ProtocolDescriptor PROTOCOL_DESCR_SYM(s21_ObjectiveCBridgeable);
/// Dynamic cast from a value type that conforms to the _ObjectiveCBridgeable
/// protocol to a class type, first by bridging the value to its Objective-C
/// object representation and then by dynamic casting that object to the
/// resulting target type.
static bool _dynamicCastValueToClassViaObjCBridgeable(
OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const Metadata *targetType,
const _ObjectiveCBridgeableWitnessTable *srcBridgeWitness,
DynamicCastFlags flags) {
// Bridge the source value to an object.
auto srcBridgedObject =
srcBridgeWitness->bridgeToObjectiveC(src, srcType, srcBridgeWitness);
// Dynamic cast the object to the resulting class type.
bool success;
if (auto cast = _dynamicCastUnknownClass(srcBridgedObject, targetType,
flags & DynamicCastFlags::Unconditional)) {
*reinterpret_cast<void **>(dest) = cast;
success = true;
} else {
// We don't need the object anymore.
swift_unknownRelease(srcBridgedObject);
success = false;
}
// Clean up the source if we're supposed to.
if (shouldDeallocateSource(success, flags)) {
srcType->vw_destroy(src);
}
// We're done.
return success;
}
/// Dynamic cast from a value type that conforms to the
/// _ObjectiveCBridgeable protocol to a class-bounded existential,
/// first by bridging the value to its Objective-C object
/// representation and then by dynamic-casting that object to the
/// resulting target type.
static bool _dynamicCastValueToClassExistentialViaObjCBridgeable(
OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const ExistentialTypeMetadata *targetType,
const _ObjectiveCBridgeableWitnessTable *srcBridgeWitness,
DynamicCastFlags flags) {
// Bridge the source value to an object.
auto srcBridgedObject =
srcBridgeWitness->bridgeToObjectiveC(src, srcType, srcBridgeWitness);
// Try to cast the object to the destination existential.
DynamicCastFlags subFlags = DynamicCastFlags::TakeOnSuccess
| DynamicCastFlags::DestroyOnFailure;
if (flags & DynamicCastFlags::Unconditional)
subFlags |= DynamicCastFlags::Unconditional;
bool success = _dynamicCastToExistential(
dest,
(OpaqueValue *)&srcBridgedObject,
swift_getObjectType(srcBridgedObject),
targetType,
subFlags);
// Clean up the source if we're supposed to.
if (shouldDeallocateSource(success, flags)) {
srcType->vw_destroy(src);
}
// We're done.
return success;
}
/// Dynamic cast from a class type to a value type that conforms to the
/// _ObjectiveCBridgeable, first by dynamic casting the object to the
/// Objective-C class to which the value type is bridged, and then bridging
/// from that object to the value type via the witness table.
static bool _dynamicCastClassToValueViaObjCBridgeable(
OpaqueValue *dest,
OpaqueValue *src,
const Metadata *srcType,
const Metadata *targetType,
const _ObjectiveCBridgeableWitnessTable *targetBridgeWitness,
DynamicCastFlags flags) {
// Determine the class type to which the target value type is bridged.
auto targetBridgedClass =
targetBridgeWitness->ObjectiveCType(targetType, targetBridgeWitness);
// Dynamic cast the source object to the class type to which the target value
// type is bridged. If we succeed, we can bridge from there; if we fail,
// there's nothing more to do.
void *srcObject = *reinterpret_cast<void * const *>(src);
if (!_dynamicCastUnknownClass(srcObject,
targetBridgedClass,
flags & DynamicCastFlags::Unconditional)) {
return _fail(src, srcType, targetType, flags);
}
// Unless we're always supposed to consume the input, retain the
// object because the witness takes it at +1.
bool alwaysConsumeSrc = (flags & DynamicCastFlags::TakeOnSuccess) &&
(flags & DynamicCastFlags::DestroyOnFailure);
if (!alwaysConsumeSrc) {
swift_unknownRetain(srcObject);
}
// The extra byte is for the tag.
auto targetSize = targetType->getValueWitnesses()->getSize() + 1;
auto targetAlignMask = targetType->getValueWitnesses()->getAlignmentMask();
// Object that frees a buffer when it goes out of scope.
struct FreeBuffer {
void *Buffer = nullptr;
size_t size, alignMask;
FreeBuffer(size_t size, size_t alignMask) :
size(size), alignMask(alignMask) {}
~FreeBuffer() {
if (Buffer)
swift_slowDealloc(Buffer, size, alignMask);
}
} freeBuffer{targetSize, targetAlignMask};
// Allocate a buffer to store the T? returned by bridging.
// The extra byte is for the tag.
const std::size_t inlineValueSize = 3 * sizeof(void*);
alignas(std::max_align_t) char inlineBuffer[inlineValueSize + 1];
void *optDestBuffer;
if (targetType->getValueWitnesses()->getStride() <= inlineValueSize) {
// Use the inline buffer.
optDestBuffer = inlineBuffer;
} else {
// Allocate a buffer.
optDestBuffer = swift_slowAlloc(targetSize, targetAlignMask);
freeBuffer.Buffer = optDestBuffer;
}
// Initialize the buffer as an empty optional.
swift_storeEnumTagSinglePayload((OpaqueValue *)optDestBuffer, targetType,
0, 1);
// Perform the bridging operation.
bool success;
if (flags & DynamicCastFlags::Unconditional) {
// For an unconditional dynamic cast, use forceBridgeFromObjectiveC.
targetBridgeWitness->forceBridgeFromObjectiveC(
(HeapObject *)srcObject, (OpaqueValue *)optDestBuffer,
targetType, targetType, targetBridgeWitness);
success = true;
} else {
// For a conditional dynamic cast, use conditionallyBridgeFromObjectiveC.
success = targetBridgeWitness->conditionallyBridgeFromObjectiveC(
(HeapObject *)srcObject, (OpaqueValue *)optDestBuffer,
targetType, targetType, targetBridgeWitness);
}
// If we succeeded, take from the optional buffer into the
// destination buffer.
if (success) {
targetType->vw_initializeWithTake(dest, (OpaqueValue *)optDestBuffer);
}
// Unless we're always supposed to consume the input, release the
// input if we need to now.
if (!alwaysConsumeSrc && shouldDeallocateSource(success, flags)) {
swift_unknownRelease(srcObject);
}
return success;
}
static id bridgeAnythingNonVerbatimToObjectiveC(OpaqueValue *src,
const Metadata *srcType,
bool consume) {
// We can always bridge objects verbatim.
if (srcType->isAnyClass()) {
id result;
memcpy(&result, src, sizeof(id));
if (!consume)
swift_unknownRetain(result);
return result;
}
// Dig through existential types.
if (auto srcExistentialTy = dyn_cast<ExistentialTypeMetadata>(srcType)) {
OpaqueValue *srcInnerValue;
const Metadata *srcInnerType;
bool isOutOfLine;
bool canTake;
unwrapExistential(src, srcExistentialTy,
srcInnerValue, srcInnerType, isOutOfLine, canTake);
auto result = bridgeAnythingNonVerbatimToObjectiveC(srcInnerValue,
srcInnerType,
consume && canTake);
// Clean up the existential, or its remains after taking the value from
// it.
if (consume) {
if (canTake) {
if (isOutOfLine) {
// Copy-on-write existentials share boxed and can't be 'take'n out of
// without a uniqueness check (which we currently don't do).
swift::fatalError(
0 /* flags */,
"Attempting to move out of a copy-on-write existential");
}
} else {
// We didn't take the value, so clean up the existential value.
srcType->vw_destroy(src);
}
}
return result;
}
// Handle metatypes.
if (isa<ExistentialMetatypeMetadata>(srcType)
|| isa<MetatypeMetadata>(srcType)) {
const Metadata *srcMetatypeValue;
memcpy(&srcMetatypeValue, src, sizeof(srcMetatypeValue));
// Class metatypes bridge to their class object.
if (isa<ClassMetadata>(srcMetatypeValue)
|| isa<ObjCClassWrapperMetadata>(srcMetatypeValue)) {
return (id)srcMetatypeValue->getObjCClassObject();
// ObjC protocols bridge to their Protocol object.
} else if (auto existential
= dyn_cast<ExistentialTypeMetadata>(srcMetatypeValue)) {
if (existential->isObjC() && existential->Protocols.NumProtocols == 1) {
// Though they're statically-allocated globals, Protocol inherits
// NSObject's default refcounting behavior so must be retained.
auto protocolObj = id_const_cast(existential->Protocols[0]);
return objc_retain(protocolObj);
}
}
} else if (auto srcBridgeWitness = findBridgeWitness(srcType)) {
// Bridge the source value to an object.
auto srcBridgedObject =
srcBridgeWitness->bridgeToObjectiveC(src, srcType, srcBridgeWitness);
// Consume if the source object was passed in +1.
if (consume)
srcType->vw_destroy(src);
return (id)srcBridgedObject;
}
// Fall back to boxing.
return (id)bridgeAnythingToSwiftValueObject(src, srcType, consume);
}
/// public func _bridgeAnythingNonVerbatimToObjectiveC<T>(_ x: T) -> AnyObject
/// Called by inlined stdlib code.
#define _bridgeAnythingNonVerbatimToObjectiveC \
MANGLE_SYM(s38_bridgeAnythingNonVerbatimToObjectiveCyyXlxlF)
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_API
id _bridgeAnythingNonVerbatimToObjectiveC(OpaqueValue *src,
const Metadata *srcType) {
bool shouldConsume = true;
SWIFT_CC_PLUSZERO_GUARD(shouldConsume = false);
return bridgeAnythingNonVerbatimToObjectiveC(src, srcType,
/*consume*/shouldConsume);
}
//===--- Bridging helpers for the Swift stdlib ----------------------------===//
// Functions that must discover and possibly use an arbitrary type's
// conformance to a given protocol. See ../core/BridgeObjectiveC.swift for
// documentation.
//===----------------------------------------------------------------------===//
#define BRIDGING_CONFORMANCE_SYM \
MANGLE_SYM(s19_BridgeableMetatypeVs21_ObjectiveCBridgeablesWP)
extern "C" const _ObjectiveCBridgeableWitnessTable BRIDGING_CONFORMANCE_SYM;
static const _ObjectiveCBridgeableWitnessTable *
findBridgeWitness(const Metadata *T) {
auto w = swift_conformsToProtocol(T,
&PROTOCOL_DESCR_SYM(s21_ObjectiveCBridgeable));
if (LLVM_LIKELY(w))
return reinterpret_cast<const _ObjectiveCBridgeableWitnessTable *>(w);
// Class and ObjC existential metatypes can be bridged, but metatypes can't
// directly conform to protocols yet. Use a stand-in conformance for a type
// that looks like a metatype value if the metatype can be bridged.
switch (T->getKind()) {
case MetadataKind::Metatype: {
auto metaTy = static_cast<const MetatypeMetadata *>(T);
if (metaTy->InstanceType->isAnyClass())
return &BRIDGING_CONFORMANCE_SYM;
break;
}
case MetadataKind::ExistentialMetatype: {
auto existentialMetaTy =
static_cast<const ExistentialMetatypeMetadata *>(T);
if (existentialMetaTy->isObjC())
return &BRIDGING_CONFORMANCE_SYM;
break;
}
case MetadataKind::Class:
case MetadataKind::Struct:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::Opaque:
case MetadataKind::Tuple:
case MetadataKind::Function:
case MetadataKind::Existential:
case MetadataKind::ObjCClassWrapper:
case MetadataKind::ForeignClass:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
break;
}
return nullptr;
}
// public func _getBridgedNonVerbatimObjectiveCType<T>(_: T.Type) -> Any.Type?
// Called by inlined stdlib code.
#define _getBridgedNonVerbatimObjectiveCType \
MANGLE_SYM(s36_getBridgedNonVerbatimObjectiveCTypeyypXpSgxmlF)
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_API
const Metadata *_getBridgedNonVerbatimObjectiveCType(
const Metadata *value, const Metadata *T
) {
// Classes and Objective-C existentials bridge verbatim.
assert(!swift_isClassOrObjCExistentialTypeImpl(T));
// Check if the type conforms to _BridgedToObjectiveC, in which case
// we'll extract its associated type.
if (const auto *bridgeWitness = findBridgeWitness(T)) {
return bridgeWitness->ObjectiveCType(T, bridgeWitness);
}
return nullptr;
}
// @_silgen_name("_bridgeNonVerbatimFromObjectiveCToAny")
// func _bridgeNonVerbatimFromObjectiveCToAny(
// x: AnyObject,
// inout result: Any?
// )
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
void
_bridgeNonVerbatimFromObjectiveCToAny(HeapObject *sourceValue,
OpaqueValue *destValue);
// @_silgen_name("_bridgeNonVerbatimBoxedValue")
// func _bridgeNonVerbatimBoxedValue<NativeType>(
// x: UnsafePointer<NativeType>,
// inout result: NativeType?
// )
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
void
_bridgeNonVerbatimBoxedValue(const OpaqueValue *sourceValue,
OpaqueValue *destValue,
const Metadata *nativeType);
// Try bridging by conversion to Any or boxing if applicable.
static bool tryBridgeNonVerbatimFromObjectiveCUniversal(
HeapObject *sourceValue,
const Metadata *nativeType,
OpaqueValue *destValue
) {
// If the type is the Any type, we can bridge by "upcasting" the object
// to Any.
if (auto nativeExistential = dyn_cast<ExistentialTypeMetadata>(nativeType)) {
if (nativeExistential->Protocols.NumProtocols == 0 &&
!nativeExistential->isClassBounded()) {
_bridgeNonVerbatimFromObjectiveCToAny(sourceValue, destValue);
return true;
}
}
// Check if the value is a box containing a value of the desired type.
if (auto srcBox = getAsSwiftValue((id)sourceValue)) {
const Metadata *sourceType;
const OpaqueValue *sourceBoxedValue;
std::tie(sourceType, sourceBoxedValue) = getValueFromSwiftValue(srcBox);
if (sourceType == nativeType) {
_bridgeNonVerbatimBoxedValue(sourceBoxedValue, destValue, nativeType);
return true;
}
}
return false;
}
// func _bridgeNonVerbatimFromObjectiveC<T>(
// _ x: AnyObject,
// _ nativeType: T.Type
// _ inout result: T?
// )
// Called by inlined stdlib code.
#define _bridgeNonVerbatimFromObjectiveC \
MANGLE_SYM(s32_bridgeNonVerbatimFromObjectiveCyyyXl_xmxSgztlF)
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_API
void
_bridgeNonVerbatimFromObjectiveC(
HeapObject *sourceValue,
const Metadata *nativeType,
OpaqueValue *destValue,
const Metadata *nativeType_
) {
if (tryBridgeNonVerbatimFromObjectiveCUniversal(sourceValue, nativeType,
destValue))
return;
// Check if the type conforms to _BridgedToObjectiveC.
if (const auto *bridgeWitness = findBridgeWitness(nativeType)) {
// Check if sourceValue has the _ObjectiveCType type required by the
// protocol.
const Metadata *objectiveCType =
bridgeWitness->ObjectiveCType(nativeType, bridgeWitness);
auto sourceValueAsObjectiveCType =
const_cast<void*>(swift_dynamicCastUnknownClass(sourceValue,
objectiveCType));
if (sourceValueAsObjectiveCType) {
// The type matches. _forceBridgeFromObjectiveC returns `Self`, so
// we can just return it directly.
bridgeWitness->forceBridgeFromObjectiveC(
static_cast<HeapObject*>(sourceValueAsObjectiveCType),
destValue, nativeType, nativeType, bridgeWitness);
return;
}
}
// Fail.
swift::crash("value type is not bridged to Objective-C");
}
/// func _bridgeNonVerbatimFromObjectiveCConditional<T>(
/// _ x: AnyObject, _ nativeType: T.Type, _ result: inout T?) -> Bool
/// Called by inlined stdlib code.
#define _bridgeNonVerbatimFromObjectiveCConditional \
MANGLE_SYM(s43_bridgeNonVerbatimFromObjectiveCConditionalySbyXl_xmxSgztlF)
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_API
bool
_bridgeNonVerbatimFromObjectiveCConditional(
HeapObject *sourceValue,
const Metadata *nativeType,
OpaqueValue *destValue,
const Metadata *nativeType_
) {
if (tryBridgeNonVerbatimFromObjectiveCUniversal(sourceValue, nativeType,
destValue))
return true;
// Local function that releases the source and returns false.
auto fail = [&] () -> bool {
SWIFT_CC_PLUSONE_GUARD(swift_unknownRelease(sourceValue));
return false;
};
// Check if the type conforms to _BridgedToObjectiveC.
const auto *bridgeWitness = findBridgeWitness(nativeType);
if (!bridgeWitness)
return fail();
// Dig out the Objective-C class type through which the native type
// is bridged.
const Metadata *objectiveCType =
bridgeWitness->ObjectiveCType(nativeType, bridgeWitness);
// Check whether we can downcast the source value to the Objective-C
// type.
auto sourceValueAsObjectiveCType =
const_cast<void*>(swift_dynamicCastUnknownClass(sourceValue,
objectiveCType));
if (!sourceValueAsObjectiveCType)
return fail();
// If the type also conforms to _ConditionallyBridgedToObjectiveC,
// use conditional bridging.
return bridgeWitness->conditionallyBridgeFromObjectiveC(
static_cast<HeapObject*>(sourceValueAsObjectiveCType),
destValue, nativeType, nativeType, bridgeWitness);
}
// func _isBridgedNonVerbatimToObjectiveC<T>(_: T.Type) -> Bool
// Called by inlined stdlib code.
#define _isBridgedNonVerbatimToObjectiveC \
MANGLE_SYM(s33_isBridgedNonVerbatimToObjectiveCySbxmlF)
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_API
bool _isBridgedNonVerbatimToObjectiveC(const Metadata *value,
const Metadata *T) {
assert(!swift_isClassOrObjCExistentialTypeImpl(T));
auto bridgeWitness = findBridgeWitness(T);
return (bool)bridgeWitness;
}
#endif
// func _isClassOrObjCExistential<T>(x: T.Type) -> Bool
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERFACE
bool _swift_isClassOrObjCExistentialType(const Metadata *value,
const Metadata *T) {
return swift_isClassOrObjCExistentialTypeImpl(T);
}
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
const Metadata *swift::_swift_class_getSuperclass(const Metadata *theClass) {
if (const ClassMetadata *classType = theClass->getClassObject())
if (classHasSuperclass(classType))
return getMetadataForClass(classType->SuperClass);
return nullptr;
}
// Called by compiler-generated cast code.
SWIFT_RUNTIME_STDLIB_API
bool swift_isClassType(const Metadata *type) {
return Metadata::isAnyKindOfClass(type->getKind());
}
// Called by compiler-generated code.
SWIFT_RUNTIME_STDLIB_API
bool swift_isOptionalType(const Metadata *type) {
return type->getKind() == MetadataKind::Optional;
}