llvm/clang/include/clang/Sema/Ownership.h

//===- 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 { … };

  /// UnionOpaquePtr - A version of OpaquePtr suitable for membership
  /// in a union.
  template <class T> struct UnionOpaquePtr { … };

} // namespace clang

namespace llvm {

  PointerLikeTypeTraits<clang::OpaquePtr<T>>;

} // namespace llvm

namespace clang {

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 { … };

/// The result of parsing/analyzing an expression, statement etc.
///
/// It may be:
/// - usable: a valid pointer to the result object
/// - unset (null but valid): for constructs that may legitimately be absent
///   (for example, the condition of a for loop)
/// - invalid: indicating an error
///   (no detail is provided, usually the error has already been diagnosed)
template <class PtrTy, bool Compress = IsResultPtrLowBitFree<PtrTy>::value>
class ActionResult { … };

// If we PtrTy has a free bit, we can represent "invalid" as nullptr|1.
ActionResult<PtrTy, true>;

/// An opaque type for threading parsed type information through the parser.
ParsedType;
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 *> { … };
template <> struct IsResultPtrLowBitFree<Stmt *> { … };
template <> struct IsResultPtrLowBitFree<CXXBaseSpecifier *> { … };
template <> struct IsResultPtrLowBitFree<CXXCtorInitializer *> { … };

ExprResult;
StmtResult;
TypeResult;
BaseResult;
MemInitResult;

DeclResult;
ParsedTemplateTy;
UnionParsedTemplateTy;

MultiExprArg;
MultiStmtArg;
ASTTemplateArgsPtr;
MultiTypeArg;
MultiTemplateParamsArg;

inline ExprResult ExprError() { … }
inline StmtResult StmtError() { … }
inline TypeResult TypeError() { … }

inline ExprResult ExprError(const StreamingDiagnostic &) { … }
inline StmtResult StmtError(const StreamingDiagnostic &) { … }

inline ExprResult ExprEmpty() { … }
inline StmtResult StmtEmpty() { … }

inline Expr *AssertSuccess(ExprResult R) { … }

inline Stmt *AssertSuccess(StmtResult R) { … }

} // namespace clang

#endif // LLVM_CLANG_SEMA_OWNERSHIP_H