include/swift/AST/StorageImpl.h - third_party/swift - Git at Google

 //===--- StorageImpl.h - Storage declaration access impl --------*- C++ -*-===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines types for describing the implementation of an
 // AbstractStorageDecl.
 //
 //===----------------------------------------------------------------------===//

 #ifndef SWIFT_STORAGEIMPL_H
 #define SWIFT_STORAGEIMPL_H

 #include "swift/Basic/Range.h"

 namespace swift {

 enum StorageIsMutable_t : bool {
   StorageIsNotMutable = false,
   StorageIsMutable = true
 };

 enum class OpaqueReadOwnership : uint8_t {
   /// An opaque read produces an owned value.
   Owned,

   /// An opaque read produces a borrowed value.
   Borrowed,

   /// An opaque read can be either owned or borrowed, depending on the
   /// preference of the caller.
   OwnedOrBorrowed
 };

 // Note that the values of these enums line up with %select values in
 // diagnostics.
 enum class AccessorKind {
 #define ACCESSOR(ID) ID,
 #define LAST_ACCESSOR(ID) Last = ID
 #include "swift/AST/AccessorKinds.def"
 };

 const unsigned NumAccessorKinds = unsigned(AccessorKind::Last) + 1;

 static inline IntRange<AccessorKind> allAccessorKinds() {
   return IntRange<AccessorKind>(AccessorKind(0),
                                 AccessorKind(NumAccessorKinds));
 }

 /// Whether an access to storage is for reading, writing, or both.
 enum class AccessKind : uint8_t {
   /// The access is just to read the current value.
   Read,

   /// The access is just to overwrite the current value.
   Write,

   /// The access may require either reading or writing the current value.
   ReadWrite
 };

 /// Produce the aggregate access kind of the combination of two accesses.
 inline AccessKind combineAccessKinds(AccessKind a, AccessKind b) {
   // If they're the same, use that; otherwise, all combinations combine
   // ReadWrite.
   return (a == b ? a : AccessKind::ReadWrite);
 }

 class AccessStrategy {
 public:
   enum Kind : uint8_t {
     /// The declaration is a VarDecl with its own physical storage; access
     /// that storage directly.
     Storage,

     /// Directly call an accessor of some sort.  The strategy includes
     /// an accessor kind.
     DirectToAccessor,

     /// Dispatch to an accessor of some sort.  The strategy includes an
     /// accessor kind.
     DispatchToAccessor,

     /// The access is a ReadWrite access and should be implemented by
     /// separately performing a Read into a temporary variable followed by
     /// a Write access back into the storage.
     MaterializeToTemporary,
   };

 private:
   Kind TheKind;
   Kind FirstKind;
   AccessorKind FirstAccessor;
   Kind SecondKind;
   AccessorKind SecondAccessor;

   AccessStrategy(Kind kind)
     : TheKind(kind) {
     assert(kind == Storage);
   }

   AccessStrategy(Kind kind, AccessorKind accessor)
     : TheKind(kind), FirstAccessor(accessor) {
     // Generally used for one of the accessor strategies, but also used
     // for constructing a first or second strategy.
   }

   AccessStrategy(AccessStrategy readStrategy, AccessStrategy writeStrategy)
     : TheKind(MaterializeToTemporary),
       FirstKind(readStrategy.TheKind),
       FirstAccessor(readStrategy.FirstAccessor),
       SecondKind(writeStrategy.TheKind),
       SecondAccessor(writeStrategy.FirstAccessor) {
     assert(readStrategy.TheKind != MaterializeToTemporary);
     assert(writeStrategy.TheKind != MaterializeToTemporary);
   }

 public:
   static AccessStrategy getStorage() {
     return { Storage };
   }

   static AccessStrategy getAccessor(AccessorKind accessor, bool dispatched) {
     return { dispatched ? DispatchToAccessor : DirectToAccessor, accessor };
   }

   static AccessStrategy getMaterializeToTemporary(AccessStrategy read,
                                                   AccessStrategy write) {
     return { read, write };
   }

   Kind getKind() const { return TheKind; }

   bool hasAccessor() const {
     return TheKind == DirectToAccessor || TheKind == DispatchToAccessor;
   }

   AccessorKind getAccessor() const {
     assert(hasAccessor());
     return FirstAccessor;
   }

   AccessStrategy getReadStrategy() const {
     assert(TheKind == MaterializeToTemporary);
     return { FirstKind, FirstAccessor };
   }
   AccessStrategy getWriteStrategy() const {
     assert(TheKind == MaterializeToTemporary);
     return { SecondKind, SecondAccessor };
   }
 };

 /// How are read accesses implemented?
 enum class ReadImplKind {
   /// There's storage.
   Stored,

   /// The superclass's read implementation is directly inherited.
   Inherited,

   /// There's a getter.
   Get,

   /// There's an immutable addressor.
   Address,

   /// There's a read coroutine.
   Read,
 };
 enum { NumReadImplKindBits = 4 };

 StringRef getReadImplKindName(ReadImplKind kind);

 /// How are simple write accesses implemented?
 enum class WriteImplKind {
   /// It's immutable.
   Immutable,

   /// There's storage.
   Stored,

   /// There are observers on top of the storage.
   /// TODO: maybe add a StoredWithDidSet here and to ReadWriteImplKind?
   StoredWithObservers,

   /// There are observers on top of the superclass's write implementation.
   InheritedWithObservers,

   /// There's a setter.
   Set,

   /// There's a mutable addressor.
   MutableAddress,

   /// There's a modify coroutine.
   Modify,
 };
 enum { NumWriteImplKindBits = 4 };

 StringRef getWriteImplKindName(WriteImplKind kind);

 /// How are read-write accesses implemented?
 enum class ReadWriteImplKind {
   /// It's immutable.
   Immutable,

   /// There's storage.
   Stored,

   /// There's a mutable addressor.
   MutableAddress,

   /// Do a read into a temporary and then a write back.
   MaterializeToTemporary,

   /// There's a modify coroutine.
   Modify,
 };
 enum { NumReadWriteImplKindBits = 4 };

 StringRef getReadWriteImplKindName(ReadWriteImplKind kind);

 class StorageImplInfo {
   using IntType = uint16_t;
   static_assert(NumReadImplKindBits + NumWriteImplKindBits
                   + NumReadWriteImplKindBits <= 16,
                 "bit count exceeds IntType range");
   IntType Read : NumReadImplKindBits;
   IntType Write : NumWriteImplKindBits;
   IntType ReadWrite : NumReadWriteImplKindBits;

 public:
   /// A convenience constructor for building immutable storage.
   StorageImplInfo(ReadImplKind readImpl)
     : StorageImplInfo(readImpl, WriteImplKind::Immutable,
                       ReadWriteImplKind::Immutable) {}

   /// The primary constructor.
   StorageImplInfo(ReadImplKind readImpl,
                   WriteImplKind writeImpl,
                   ReadWriteImplKind readWriteImpl)
     : Read(IntType(readImpl)),
       Write(IntType(writeImpl)),
       ReadWrite(IntType(readWriteImpl)) {
 #ifndef NDEBUG
     assert((writeImpl == WriteImplKind::Immutable)
              == (readWriteImpl == ReadWriteImplKind::Immutable) &&
            "write and read-write disagree about immutability");

     switch (writeImpl) {
     case WriteImplKind::Immutable:
       // No other consistency checks are required if the storage is immutable.
       return;

     case WriteImplKind::Stored:
       assert(readImpl == ReadImplKind::Stored);
       assert(readWriteImpl == ReadWriteImplKind::Stored);
       return;

     case WriteImplKind::StoredWithObservers:
       assert(readImpl == ReadImplKind::Stored);
       assert(readWriteImpl == ReadWriteImplKind::MaterializeToTemporary);
       return;

     case WriteImplKind::InheritedWithObservers:
       assert(readImpl == ReadImplKind::Inherited);
       assert(readWriteImpl == ReadWriteImplKind::MaterializeToTemporary);
       return;

     case WriteImplKind::Set:
       assert(readImpl == ReadImplKind::Get ||
              readImpl == ReadImplKind::Address ||
              readImpl == ReadImplKind::Read);
       assert(readWriteImpl == ReadWriteImplKind::MaterializeToTemporary ||
              readWriteImpl == ReadWriteImplKind::Modify);
       return;

     case WriteImplKind::Modify:
       assert(readImpl == ReadImplKind::Get ||
              readImpl == ReadImplKind::Address ||
              readImpl == ReadImplKind::Read);
       assert(readWriteImpl == ReadWriteImplKind::Modify);
       return;

     case WriteImplKind::MutableAddress:
       assert(readImpl == ReadImplKind::Get ||
              readImpl == ReadImplKind::Address ||
              readImpl == ReadImplKind::Read);
       assert(readWriteImpl == ReadWriteImplKind::MutableAddress);
       return;
     }
     llvm_unreachable("bad write impl kind");
 #endif
   }

   static StorageImplInfo getSimpleStored(StorageIsMutable_t isMutable) {
     return { ReadImplKind::Stored,
              isMutable ? WriteImplKind::Stored
                        : WriteImplKind::Immutable,
              isMutable ? ReadWriteImplKind::Stored
                        : ReadWriteImplKind::Immutable };
   }

   static StorageImplInfo getOpaque(StorageIsMutable_t isMutable,
                                    OpaqueReadOwnership ownership) {
     return (isMutable ? getMutableOpaque(ownership)
                       : getImmutableOpaque(ownership));
   }

   /// Describe the implementation of a immutable property implemented opaquely.
   static StorageImplInfo getImmutableOpaque(OpaqueReadOwnership ownership) {
     return { getOpaqueReadImpl(ownership) };
   }

   /// Describe the implementation of a mutable property implemented opaquely.
   static StorageImplInfo getMutableOpaque(OpaqueReadOwnership ownership) {
     return { getOpaqueReadImpl(ownership), WriteImplKind::Set,
              ReadWriteImplKind::Modify };
   }

   static StorageImplInfo getComputed(StorageIsMutable_t isMutable) {
     return (isMutable ? getMutableComputed()
                       : getImmutableComputed());
   }

   /// Describe the implementation of an immutable property implemented
   /// with just a getter.
   static StorageImplInfo getImmutableComputed() {
     return { ReadImplKind::Get };
   }

   /// Describe the implementation of a mutable property implemented with
   /// getter and setter.
   static StorageImplInfo getMutableComputed() {
     return { ReadImplKind::Get, WriteImplKind::Set,
              ReadWriteImplKind::MaterializeToTemporary };
   }

   /// Does this implementation description require storage?
   bool hasStorage() const {
     return getReadImpl() == ReadImplKind::Stored;
   }

   /// Does this describe a simply-stored variable?
   bool isSimpleStored() const {
     return getReadImpl() == ReadImplKind::Stored &&
            (getWriteImpl() == WriteImplKind::Stored ||
             getWriteImpl() == WriteImplKind::Immutable);
   }

   /// Does this describe storage that supports mutation?
   StorageIsMutable_t supportsMutation() const {
     return StorageIsMutable_t(getWriteImpl() != WriteImplKind::Immutable);
   }

   ReadImplKind getReadImpl() const {
     return ReadImplKind(Read);
   }
   WriteImplKind getWriteImpl() const {
     return WriteImplKind(Write);
   }
   ReadWriteImplKind getReadWriteImpl() const {
     return ReadWriteImplKind(ReadWrite);
   }

 private:
   static ReadImplKind getOpaqueReadImpl(OpaqueReadOwnership ownership) {
     switch (ownership) {
     case OpaqueReadOwnership::Owned:
       return ReadImplKind::Get;
     case OpaqueReadOwnership::OwnedOrBorrowed:
     case OpaqueReadOwnership::Borrowed:
       return ReadImplKind::Read;
     }
     llvm_unreachable("bad read-ownership kind");
   }
 };

 } // end namespace swift

 #endif
	//===--- StorageImpl.h - Storage declaration access impl --------- C++ --===//
	//
	// 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
	//
	//===----------------------------------------------------------------------===//
	//
	// This file defines types for describing the implementation of an
	// AbstractStorageDecl.
	//
	//===----------------------------------------------------------------------===//

	#ifndef SWIFT_STORAGEIMPL_H
	#define SWIFT_STORAGEIMPL_H

	#include "swift/Basic/Range.h"

	namespace swift {

	enum StorageIsMutable_t : bool {
	StorageIsNotMutable = false,
	StorageIsMutable = true
	};

	enum class OpaqueReadOwnership : uint8_t {
	/// An opaque read produces an owned value.
	Owned,

	/// An opaque read produces a borrowed value.
	Borrowed,

	/// An opaque read can be either owned or borrowed, depending on the
	/// preference of the caller.
	OwnedOrBorrowed
	};

	// Note that the values of these enums line up with %select values in
	// diagnostics.
	enum class AccessorKind {
	#define ACCESSOR(ID) ID,
	#define LAST_ACCESSOR(ID) Last = ID
	#include "swift/AST/AccessorKinds.def"
	};

	const unsigned NumAccessorKinds = unsigned(AccessorKind::Last) + 1;

	static inline IntRange<AccessorKind> allAccessorKinds() {
	return IntRange<AccessorKind>(AccessorKind(0),
	AccessorKind(NumAccessorKinds));
	}

	/// Whether an access to storage is for reading, writing, or both.
	enum class AccessKind : uint8_t {
	/// The access is just to read the current value.
	Read,

	/// The access is just to overwrite the current value.
	Write,

	/// The access may require either reading or writing the current value.
	ReadWrite
	};

	/// Produce the aggregate access kind of the combination of two accesses.
	inline AccessKind combineAccessKinds(AccessKind a, AccessKind b) {
	// If they're the same, use that; otherwise, all combinations combine
	// ReadWrite.
	return (a == b ? a : AccessKind::ReadWrite);
	}

	class AccessStrategy {
	public:
	enum Kind : uint8_t {
	/// The declaration is a VarDecl with its own physical storage; access
	/// that storage directly.
	Storage,

	/// Directly call an accessor of some sort. The strategy includes
	/// an accessor kind.
	DirectToAccessor,

	/// Dispatch to an accessor of some sort. The strategy includes an
	/// accessor kind.
	DispatchToAccessor,

	/// The access is a ReadWrite access and should be implemented by
	/// separately performing a Read into a temporary variable followed by
	/// a Write access back into the storage.
	MaterializeToTemporary,
	};

	private:
	Kind TheKind;
	Kind FirstKind;
	AccessorKind FirstAccessor;
	Kind SecondKind;
	AccessorKind SecondAccessor;

	AccessStrategy(Kind kind)
	: TheKind(kind) {
	assert(kind == Storage);
	}

	AccessStrategy(Kind kind, AccessorKind accessor)
	: TheKind(kind), FirstAccessor(accessor) {
	// Generally used for one of the accessor strategies, but also used
	// for constructing a first or second strategy.
	}

	AccessStrategy(AccessStrategy readStrategy, AccessStrategy writeStrategy)
	: TheKind(MaterializeToTemporary),
	FirstKind(readStrategy.TheKind),
	FirstAccessor(readStrategy.FirstAccessor),
	SecondKind(writeStrategy.TheKind),
	SecondAccessor(writeStrategy.FirstAccessor) {
	assert(readStrategy.TheKind != MaterializeToTemporary);
	assert(writeStrategy.TheKind != MaterializeToTemporary);
	}

	public:
	static AccessStrategy getStorage() {
	return { Storage };
	}

	static AccessStrategy getAccessor(AccessorKind accessor, bool dispatched) {
	return { dispatched ? DispatchToAccessor : DirectToAccessor, accessor };
	}

	static AccessStrategy getMaterializeToTemporary(AccessStrategy read,
	AccessStrategy write) {
	return { read, write };
	}

	Kind getKind() const { return TheKind; }

	bool hasAccessor() const {
	return TheKind == DirectToAccessor \|\| TheKind == DispatchToAccessor;
	}

	AccessorKind getAccessor() const {
	assert(hasAccessor());
	return FirstAccessor;
	}

	AccessStrategy getReadStrategy() const {
	assert(TheKind == MaterializeToTemporary);
	return { FirstKind, FirstAccessor };
	}
	AccessStrategy getWriteStrategy() const {
	assert(TheKind == MaterializeToTemporary);
	return { SecondKind, SecondAccessor };
	}
	};

	/// How are read accesses implemented?
	enum class ReadImplKind {
	/// There's storage.
	Stored,

	/// The superclass's read implementation is directly inherited.
	Inherited,

	/// There's a getter.
	Get,

	/// There's an immutable addressor.
	Address,

	/// There's a read coroutine.
	Read,
	};
	enum { NumReadImplKindBits = 4 };

	StringRef getReadImplKindName(ReadImplKind kind);

	/// How are simple write accesses implemented?
	enum class WriteImplKind {
	/// It's immutable.
	Immutable,

	/// There's storage.
	Stored,

	/// There are observers on top of the storage.
	/// TODO: maybe add a StoredWithDidSet here and to ReadWriteImplKind?
	StoredWithObservers,

	/// There are observers on top of the superclass's write implementation.
	InheritedWithObservers,

	/// There's a setter.
	Set,

	/// There's a mutable addressor.
	MutableAddress,

	/// There's a modify coroutine.
	Modify,
	};
	enum { NumWriteImplKindBits = 4 };

	StringRef getWriteImplKindName(WriteImplKind kind);

	/// How are read-write accesses implemented?
	enum class ReadWriteImplKind {
	/// It's immutable.
	Immutable,

	/// There's storage.
	Stored,

	/// There's a mutable addressor.
	MutableAddress,

	/// Do a read into a temporary and then a write back.
	MaterializeToTemporary,

	/// There's a modify coroutine.
	Modify,
	};
	enum { NumReadWriteImplKindBits = 4 };

	StringRef getReadWriteImplKindName(ReadWriteImplKind kind);

	class StorageImplInfo {
	using IntType = uint16_t;
	static_assert(NumReadImplKindBits + NumWriteImplKindBits
	+ NumReadWriteImplKindBits <= 16,
	"bit count exceeds IntType range");
	IntType Read : NumReadImplKindBits;
	IntType Write : NumWriteImplKindBits;
	IntType ReadWrite : NumReadWriteImplKindBits;

	public:
	/// A convenience constructor for building immutable storage.
	StorageImplInfo(ReadImplKind readImpl)
	: StorageImplInfo(readImpl, WriteImplKind::Immutable,
	ReadWriteImplKind::Immutable) {}

	/// The primary constructor.
	StorageImplInfo(ReadImplKind readImpl,
	WriteImplKind writeImpl,
	ReadWriteImplKind readWriteImpl)
	: Read(IntType(readImpl)),
	Write(IntType(writeImpl)),
	ReadWrite(IntType(readWriteImpl)) {
	#ifndef NDEBUG
	assert((writeImpl == WriteImplKind::Immutable)
	== (readWriteImpl == ReadWriteImplKind::Immutable) &&
	"write and read-write disagree about immutability");

	switch (writeImpl) {
	case WriteImplKind::Immutable:
	// No other consistency checks are required if the storage is immutable.
	return;

	case WriteImplKind::Stored:
	assert(readImpl == ReadImplKind::Stored);
	assert(readWriteImpl == ReadWriteImplKind::Stored);
	return;

	case WriteImplKind::StoredWithObservers:
	assert(readImpl == ReadImplKind::Stored);
	assert(readWriteImpl == ReadWriteImplKind::MaterializeToTemporary);
	return;

	case WriteImplKind::InheritedWithObservers:
	assert(readImpl == ReadImplKind::Inherited);
	assert(readWriteImpl == ReadWriteImplKind::MaterializeToTemporary);
	return;

	case WriteImplKind::Set:
	assert(readImpl == ReadImplKind::Get \|\|
	readImpl == ReadImplKind::Address \|\|
	readImpl == ReadImplKind::Read);
	assert(readWriteImpl == ReadWriteImplKind::MaterializeToTemporary \|\|
	readWriteImpl == ReadWriteImplKind::Modify);
	return;

	case WriteImplKind::Modify:
	assert(readImpl == ReadImplKind::Get \|\|
	readImpl == ReadImplKind::Address \|\|
	readImpl == ReadImplKind::Read);
	assert(readWriteImpl == ReadWriteImplKind::Modify);
	return;

	case WriteImplKind::MutableAddress:
	assert(readImpl == ReadImplKind::Get \|\|
	readImpl == ReadImplKind::Address \|\|
	readImpl == ReadImplKind::Read);
	assert(readWriteImpl == ReadWriteImplKind::MutableAddress);
	return;
	}
	llvm_unreachable("bad write impl kind");
	#endif
	}

	static StorageImplInfo getSimpleStored(StorageIsMutable_t isMutable) {
	return { ReadImplKind::Stored,
	isMutable ? WriteImplKind::Stored
	: WriteImplKind::Immutable,
	isMutable ? ReadWriteImplKind::Stored
	: ReadWriteImplKind::Immutable };
	}

	static StorageImplInfo getOpaque(StorageIsMutable_t isMutable,
	OpaqueReadOwnership ownership) {
	return (isMutable ? getMutableOpaque(ownership)
	: getImmutableOpaque(ownership));
	}

	/// Describe the implementation of a immutable property implemented opaquely.
	static StorageImplInfo getImmutableOpaque(OpaqueReadOwnership ownership) {
	return { getOpaqueReadImpl(ownership) };
	}

	/// Describe the implementation of a mutable property implemented opaquely.
	static StorageImplInfo getMutableOpaque(OpaqueReadOwnership ownership) {
	return { getOpaqueReadImpl(ownership), WriteImplKind::Set,
	ReadWriteImplKind::Modify };
	}

	static StorageImplInfo getComputed(StorageIsMutable_t isMutable) {
	return (isMutable ? getMutableComputed()
	: getImmutableComputed());
	}

	/// Describe the implementation of an immutable property implemented
	/// with just a getter.
	static StorageImplInfo getImmutableComputed() {
	return { ReadImplKind::Get };
	}

	/// Describe the implementation of a mutable property implemented with
	/// getter and setter.
	static StorageImplInfo getMutableComputed() {
	return { ReadImplKind::Get, WriteImplKind::Set,
	ReadWriteImplKind::MaterializeToTemporary };
	}

	/// Does this implementation description require storage?
	bool hasStorage() const {
	return getReadImpl() == ReadImplKind::Stored;
	}

	/// Does this describe a simply-stored variable?
	bool isSimpleStored() const {
	return getReadImpl() == ReadImplKind::Stored &&
	(getWriteImpl() == WriteImplKind::Stored \|\|
	getWriteImpl() == WriteImplKind::Immutable);
	}

	/// Does this describe storage that supports mutation?
	StorageIsMutable_t supportsMutation() const {
	return StorageIsMutable_t(getWriteImpl() != WriteImplKind::Immutable);
	}

	ReadImplKind getReadImpl() const {
	return ReadImplKind(Read);
	}
	WriteImplKind getWriteImpl() const {
	return WriteImplKind(Write);
	}
	ReadWriteImplKind getReadWriteImpl() const {
	return ReadWriteImplKind(ReadWrite);
	}

	private:
	static ReadImplKind getOpaqueReadImpl(OpaqueReadOwnership ownership) {
	switch (ownership) {
	case OpaqueReadOwnership::Owned:
	return ReadImplKind::Get;
	case OpaqueReadOwnership::OwnedOrBorrowed:
	case OpaqueReadOwnership::Borrowed:
	return ReadImplKind::Read;
	}
	llvm_unreachable("bad read-ownership kind");
	}
	};

	} // end namespace swift

	#endif