CurrentSourceLocExprScope.h

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//===--- CurrentSourceLocExprScope.h ----------------------------*- 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 defines types used to track the current context needed to evaluate
//  a SourceLocExpr.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_CLANG_AST_CURRENTSOURCELOCEXPRSCOPE_H
#define LLVM_CLANG_AST_CURRENTSOURCELOCEXPRSCOPE_H
 
#include <cassert>
 
namespace clang {
class Expr;
 
/// Represents the current source location and context used to determine the
/// value of the source location builtins (ex. __builtin_LINE), including the
/// context of default argument and default initializer expressions.
class CurrentSourceLocExprScope {
  /// The CXXDefaultArgExpr or CXXDefaultInitExpr we're currently evaluating.
  const Expr *DefaultExpr = nullptr;
 
public:
  /// A RAII style scope guard used for tracking the current source
  /// location and context as used by the source location builtins
  /// (ex. __builtin_LINE).
  class SourceLocExprScopeGuard;
 
  const Expr *getDefaultExpr() const { return DefaultExpr; }
 
  explicit CurrentSourceLocExprScope() = default;
 
private:
  explicit CurrentSourceLocExprScope(const Expr *DefaultExpr)
      : DefaultExpr(DefaultExpr) {}
 
  CurrentSourceLocExprScope(CurrentSourceLocExprScope const &) = default;
  CurrentSourceLocExprScope &
  operator=(CurrentSourceLocExprScope const &) = default;
};
 
class CurrentSourceLocExprScope::SourceLocExprScopeGuard {
public:
  SourceLocExprScopeGuard(const Expr *DefaultExpr,
                          CurrentSourceLocExprScope &Current)
      : Current(Current), OldVal(Current), Enable(false) {
    assert(DefaultExpr && "the new scope should not be empty");
    if ((Enable = (Current.getDefaultExpr() == nullptr)))
      Current = CurrentSourceLocExprScope(DefaultExpr);
  }
 
  ~SourceLocExprScopeGuard() {
    if (Enable)
      Current = OldVal;
  }
 
private:
  SourceLocExprScopeGuard(SourceLocExprScopeGuard const &) = delete;
  SourceLocExprScopeGuard &operator=(SourceLocExprScopeGuard const &) = delete;
 
  CurrentSourceLocExprScope &Current;
  CurrentSourceLocExprScope OldVal;
  bool Enable;
};
 
} // end namespace clang
 
#endif // LLVM_CLANG_AST_CURRENTSOURCELOCEXPRSCOPE_H