Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- Ownership.h - Parser ownership helpers -------------------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

//  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/AST/Expr.h"

#include "clang/Basic/LLVM.h"

#include "llvm/ADT/ArrayRef.h"

#include "llvm/Support/PointerLikeTypeTraits.h"

#include "llvm/Support/type_traits.h"

#include <cassert>

#include <cstddef>

#include <cstdint>

//===----------------------------------------------------------------------===//

// OpaquePtr

//===----------------------------------------------------------------------===//

namespace clang {

class CXXBaseSpecifier;

class CXXCtorInitializer;

class Decl;

class Expr;

class ParsedTemplateArgument;

class QualType;

class Stmt;

class TemplateName;

class TemplateParameterList;

  /// 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 = nullptr;

    explicit OpaquePtr(void *Ptr) : Ptr(Ptr) {}

    using Traits = llvm::PointerLikeTypeTraits<PtrTy>;

  public:

    OpaquePtr(std::nullptr_t = nullptr) {}

    static OpaquePtr make(PtrTy P) { OpaquePtr OP; OP.set(P); return OP; }

    /// 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();

    }

    /// 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);

    }

    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 clang

namespace llvm {

  template <class T>

  struct PointerLikeTypeTraits<clang::OpaquePtr<T>> {

    static constexpr int NumLowBitsAvailable = 0;

    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);

    }

  };

} // namespace llvm

namespace clang {

  // Basic

class StreamingDiagnostic;

// 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 *) = delete;

    ActionResult(volatile void *) = delete;

    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;

    using PtrTraits = llvm::PointerLikeTypeTraits<PtrTy>;

  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 *) = delete;

    ActionResult(volatile void *) = delete;

    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.

  using ParsedType = OpaquePtr<QualType>;

  using UnionParsedType = UnionOpaquePtr<QualType>;

  // 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;

  };

  using ExprResult = ActionResult<Expr *>;

  using StmtResult = ActionResult<Stmt *>;

  using TypeResult = ActionResult<ParsedType>;

  using BaseResult = ActionResult<CXXBaseSpecifier *>;

  using MemInitResult = ActionResult<CXXCtorInitializer *>;

  using DeclResult = ActionResult<Decl *>;

  using ParsedTemplateTy = OpaquePtr<TemplateName>;

  using UnionParsedTemplateTy = UnionOpaquePtr<TemplateName>;

  using MultiExprArg = MutableArrayRef<Expr *>;

  using MultiStmtArg = MutableArrayRef<Stmt *>;

  using ASTTemplateArgsPtr = MutableArrayRef<ParsedTemplateArgument>;

  using MultiTypeArg = MutableArrayRef<ParsedType>;

  using MultiTemplateParamsArg = MutableArrayRef<TemplateParameterList *>;

  inline ExprResult ExprError() { return ExprResult(true); }

  inline StmtResult StmtError() { return StmtResult(true); }

  inline TypeResult TypeError() { return TypeResult(true); }

  inline ExprResult ExprError(const StreamingDiagnostic &) {

    return ExprError();

  }

  inline StmtResult StmtError(const StreamingDiagnostic &) {

    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();

  }

} // namespace clang

#endif // LLVM_CLANG_SEMA_OWNERSHIP_H