1 //===--- CurrentSourceLocExprScope.h ----------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 //  This file defines types used to track the current context needed to evaluate
11 //  a SourceLocExpr.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_CLANG_AST_CURRENT_SOURCE_LOC_EXPR_SCOPE_H
16 #define LLVM_CLANG_AST_CURRENT_SOURCE_LOC_EXPR_SCOPE_H
17 
18 #include <cassert>
19 
20 namespace clang {
21 class Expr;
22 
23 /// Represents the current source location and context used to determine the
24 /// value of the source location builtins (ex. __builtin_LINE), including the
25 /// context of default argument and default initializer expressions.
26 class CurrentSourceLocExprScope {
27   /// The CXXDefaultArgExpr or CXXDefaultInitExpr we're currently evaluating.
28   const Expr *DefaultExpr = nullptr;
29 
30 public:
31   /// A RAII style scope guard used for tracking the current source
32   /// location and context as used by the source location builtins
33   /// (ex. __builtin_LINE).
34   class SourceLocExprScopeGuard;
35 
getDefaultExpr()36   const Expr *getDefaultExpr() const { return DefaultExpr; }
37 
38   explicit CurrentSourceLocExprScope() = default;
39 
40 private:
CurrentSourceLocExprScope(const Expr * DefaultExpr)41   explicit CurrentSourceLocExprScope(const Expr *DefaultExpr)
42       : DefaultExpr(DefaultExpr) {}
43 
44   CurrentSourceLocExprScope(CurrentSourceLocExprScope const &) = default;
45   CurrentSourceLocExprScope &
46   operator=(CurrentSourceLocExprScope const &) = default;
47 };
48 
49 class CurrentSourceLocExprScope::SourceLocExprScopeGuard {
50 public:
SourceLocExprScopeGuard(const Expr * DefaultExpr,CurrentSourceLocExprScope & Current)51   SourceLocExprScopeGuard(const Expr *DefaultExpr,
52                           CurrentSourceLocExprScope &Current)
53       : Current(Current), OldVal(Current), Enable(false) {
54     assert(DefaultExpr && "the new scope should not be empty");
55     if ((Enable = (Current.getDefaultExpr() == nullptr)))
56       Current = CurrentSourceLocExprScope(DefaultExpr);
57   }
58 
~SourceLocExprScopeGuard()59   ~SourceLocExprScopeGuard() {
60     if (Enable)
61       Current = OldVal;
62   }
63 
64 private:
65   SourceLocExprScopeGuard(SourceLocExprScopeGuard const &) = delete;
66   SourceLocExprScopeGuard &operator=(SourceLocExprScopeGuard const &) = delete;
67 
68   CurrentSourceLocExprScope &Current;
69   CurrentSourceLocExprScope OldVal;
70   bool Enable;
71 };
72 
73 } // end namespace clang
74 
75 #endif // LLVM_CLANG_AST_CURRENT_SOURCE_LOC_EXPR_SCOPE_H
76