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+//===--- Ownership.h - Parser ownership helpers -----------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains classes for managing ownership of Stmt and Expr nodes.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_SEMA_OWNERSHIP_H
+#define LLVM_CLANG_SEMA_OWNERSHIP_H
+
+#include "clang/Basic/LLVM.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/PointerIntPair.h"
+
+//===----------------------------------------------------------------------===//
+// OpaquePtr
+//===----------------------------------------------------------------------===//
+
+namespace clang {
+ class CXXCtorInitializer;
+ class CXXBaseSpecifier;
+ class Decl;
+ class Expr;
+ class ParsedTemplateArgument;
+ class QualType;
+ class Stmt;
+ class TemplateName;
+ class TemplateParameterList;
+
+ /// \brief Wrapper for void* pointer.
+ /// \tparam PtrTy Either a pointer type like 'T*' or a type that behaves like
+ /// a pointer.
+ ///
+ /// This is a very simple POD type that wraps a pointer that the Parser
+ /// doesn't know about but that Sema or another client does. The PtrTy
+ /// template argument is used to make sure that "Decl" pointers are not
+ /// compatible with "Type" pointers for example.
+ template <class PtrTy>
+ class OpaquePtr {
+ void *Ptr;
+ explicit OpaquePtr(void *Ptr) : Ptr(Ptr) {}
+
+ typedef llvm::PointerLikeTypeTraits<PtrTy> Traits;
+
+ public:
+ OpaquePtr() : Ptr(nullptr) {}
+
+ static OpaquePtr make(PtrTy P) { OpaquePtr OP; OP.set(P); return OP; }
+
+ /// \brief Returns plain pointer to the entity pointed by this wrapper.
+ /// \tparam PointeeT Type of pointed entity.
+ ///
+ /// It is identical to getPtrAs<PointeeT*>.
+ template <typename PointeeT> PointeeT* getPtrTo() const {
+ return get();
+ }
+
+ /// \brief Returns pointer converted to the specified type.
+ /// \tparam PtrT Result pointer type. There must be implicit conversion
+ /// from PtrTy to PtrT.
+ ///
+ /// In contrast to getPtrTo, this method allows the return type to be
+ /// a smart pointer.
+ template <typename PtrT> PtrT getPtrAs() const {
+ return get();
+ }
+
+ PtrTy get() const {
+ return Traits::getFromVoidPointer(Ptr);
+ }
+
+ void set(PtrTy P) {
+ Ptr = Traits::getAsVoidPointer(P);
+ }
+
+ LLVM_EXPLICIT operator bool() const { return Ptr != nullptr; }
+
+ void *getAsOpaquePtr() const { return Ptr; }
+ static OpaquePtr getFromOpaquePtr(void *P) { return OpaquePtr(P); }
+ };
+
+ /// UnionOpaquePtr - A version of OpaquePtr suitable for membership
+ /// in a union.
+ template <class T> struct UnionOpaquePtr {
+ void *Ptr;
+
+ static UnionOpaquePtr make(OpaquePtr<T> P) {
+ UnionOpaquePtr OP = { P.getAsOpaquePtr() };
+ return OP;
+ }
+
+ OpaquePtr<T> get() const { return OpaquePtr<T>::getFromOpaquePtr(Ptr); }
+ operator OpaquePtr<T>() const { return get(); }
+
+ UnionOpaquePtr &operator=(OpaquePtr<T> P) {
+ Ptr = P.getAsOpaquePtr();
+ return *this;
+ }
+ };
+}
+
+namespace llvm {
+ template <class T>
+ class PointerLikeTypeTraits<clang::OpaquePtr<T> > {
+ public:
+ static inline void *getAsVoidPointer(clang::OpaquePtr<T> P) {
+ // FIXME: Doesn't work? return P.getAs< void >();
+ return P.getAsOpaquePtr();
+ }
+ static inline clang::OpaquePtr<T> getFromVoidPointer(void *P) {
+ return clang::OpaquePtr<T>::getFromOpaquePtr(P);
+ }
+ enum { NumLowBitsAvailable = 0 };
+ };
+
+ template <class T>
+ struct isPodLike<clang::OpaquePtr<T> > { static const bool value = true; };
+}
+
+namespace clang {
+ // Basic
+ class DiagnosticBuilder;
+
+ // Determines whether the low bit of the result pointer for the
+ // given UID is always zero. If so, ActionResult will use that bit
+ // for it's "invalid" flag.
+ template<class Ptr>
+ struct IsResultPtrLowBitFree {
+ static const bool value = false;
+ };
+
+ /// ActionResult - This structure is used while parsing/acting on
+ /// expressions, stmts, etc. It encapsulates both the object returned by
+ /// the action, plus a sense of whether or not it is valid.
+ /// When CompressInvalid is true, the "invalid" flag will be
+ /// stored in the low bit of the Val pointer.
+ template<class PtrTy,
+ bool CompressInvalid = IsResultPtrLowBitFree<PtrTy>::value>
+ class ActionResult {
+ PtrTy Val;
+ bool Invalid;
+
+ public:
+ ActionResult(bool Invalid = false)
+ : Val(PtrTy()), Invalid(Invalid) {}
+ ActionResult(PtrTy val) : Val(val), Invalid(false) {}
+ ActionResult(const DiagnosticBuilder &) : Val(PtrTy()), Invalid(true) {}
+
+ // These two overloads prevent void* -> bool conversions.
+ ActionResult(const void *);
+ ActionResult(volatile void *);
+
+ bool isInvalid() const { return Invalid; }
+ bool isUsable() const { return !Invalid && Val; }
+ bool isUnset() const { return !Invalid && !Val; }
+
+ PtrTy get() const { return Val; }
+ template <typename T> T *getAs() { return static_cast<T*>(get()); }
+
+ void set(PtrTy V) { Val = V; }
+
+ const ActionResult &operator=(PtrTy RHS) {
+ Val = RHS;
+ Invalid = false;
+ return *this;
+ }
+ };
+
+ // This ActionResult partial specialization places the "invalid"
+ // flag into the low bit of the pointer.
+ template<typename PtrTy>
+ class ActionResult<PtrTy, true> {
+ // A pointer whose low bit is 1 if this result is invalid, 0
+ // otherwise.
+ uintptr_t PtrWithInvalid;
+ typedef llvm::PointerLikeTypeTraits<PtrTy> PtrTraits;
+ public:
+ ActionResult(bool Invalid = false)
+ : PtrWithInvalid(static_cast<uintptr_t>(Invalid)) { }
+
+ ActionResult(PtrTy V) {
+ void *VP = PtrTraits::getAsVoidPointer(V);
+ PtrWithInvalid = reinterpret_cast<uintptr_t>(VP);
+ assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer");
+ }
+ ActionResult(const DiagnosticBuilder &) : PtrWithInvalid(0x01) { }
+
+ // These two overloads prevent void* -> bool conversions.
+ ActionResult(const void *);
+ ActionResult(volatile void *);
+
+ bool isInvalid() const { return PtrWithInvalid & 0x01; }
+ bool isUsable() const { return PtrWithInvalid > 0x01; }
+ bool isUnset() const { return PtrWithInvalid == 0; }
+
+ PtrTy get() const {
+ void *VP = reinterpret_cast<void *>(PtrWithInvalid & ~0x01);
+ return PtrTraits::getFromVoidPointer(VP);
+ }
+ template <typename T> T *getAs() { return static_cast<T*>(get()); }
+
+ void set(PtrTy V) {
+ void *VP = PtrTraits::getAsVoidPointer(V);
+ PtrWithInvalid = reinterpret_cast<uintptr_t>(VP);
+ assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer");
+ }
+
+ const ActionResult &operator=(PtrTy RHS) {
+ void *VP = PtrTraits::getAsVoidPointer(RHS);
+ PtrWithInvalid = reinterpret_cast<uintptr_t>(VP);
+ assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer");
+ return *this;
+ }
+
+ // For types where we can fit a flag in with the pointer, provide
+ // conversions to/from pointer type.
+ static ActionResult getFromOpaquePointer(void *P) {
+ ActionResult Result;
+ Result.PtrWithInvalid = (uintptr_t)P;
+ return Result;
+ }
+ void *getAsOpaquePointer() const { return (void*)PtrWithInvalid; }
+ };
+
+ /// An opaque type for threading parsed type information through the
+ /// parser.
+ typedef OpaquePtr<QualType> ParsedType;
+ typedef UnionOpaquePtr<QualType> UnionParsedType;
+
+ // We can re-use the low bit of expression, statement, base, and
+ // member-initializer pointers for the "invalid" flag of
+ // ActionResult.
+ template<> struct IsResultPtrLowBitFree<Expr*> {
+ static const bool value = true;
+ };
+ template<> struct IsResultPtrLowBitFree<Stmt*> {
+ static const bool value = true;
+ };
+ template<> struct IsResultPtrLowBitFree<CXXBaseSpecifier*> {
+ static const bool value = true;
+ };
+ template<> struct IsResultPtrLowBitFree<CXXCtorInitializer*> {
+ static const bool value = true;
+ };
+
+ typedef ActionResult<Expr*> ExprResult;
+ typedef ActionResult<Stmt*> StmtResult;
+ typedef ActionResult<ParsedType> TypeResult;
+ typedef ActionResult<CXXBaseSpecifier*> BaseResult;
+ typedef ActionResult<CXXCtorInitializer*> MemInitResult;
+
+ typedef ActionResult<Decl*> DeclResult;
+ typedef OpaquePtr<TemplateName> ParsedTemplateTy;
+
+ typedef MutableArrayRef<Expr*> MultiExprArg;
+ typedef MutableArrayRef<Stmt*> MultiStmtArg;
+ typedef MutableArrayRef<ParsedTemplateArgument> ASTTemplateArgsPtr;
+ typedef MutableArrayRef<ParsedType> MultiTypeArg;
+ typedef MutableArrayRef<TemplateParameterList*> MultiTemplateParamsArg;
+
+ inline ExprResult ExprError() { return ExprResult(true); }
+ inline StmtResult StmtError() { return StmtResult(true); }
+
+ inline ExprResult ExprError(const DiagnosticBuilder&) { return ExprError(); }
+ inline StmtResult StmtError(const DiagnosticBuilder&) { return StmtError(); }
+
+ inline ExprResult ExprEmpty() { return ExprResult(false); }
+ inline StmtResult StmtEmpty() { return StmtResult(false); }
+
+ inline Expr *AssertSuccess(ExprResult R) {
+ assert(!R.isInvalid() && "operation was asserted to never fail!");
+ return R.get();
+ }
+
+ inline Stmt *AssertSuccess(StmtResult R) {
+ assert(!R.isInvalid() && "operation was asserted to never fail!");
+ return R.get();
+ }
+}
+
+#endif