1//===--- EvaluatedExprVisitor.h - Evaluated expression visitor --*- 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 the EvaluatedExprVisitor class template, which visits
11//  the potentially-evaluated subexpressions of a potentially-evaluated
12//  expression.
13//
14//===----------------------------------------------------------------------===//
15#ifndef LLVM_CLANG_AST_EVALUATEDEXPRVISITOR_H
16#define LLVM_CLANG_AST_EVALUATEDEXPRVISITOR_H
17
18#include "clang/AST/DeclCXX.h"
19#include "clang/AST/Expr.h"
20#include "clang/AST/ExprCXX.h"
21#include "clang/AST/StmtVisitor.h"
22
23namespace clang {
24
25class ASTContext;
26
27/// \brief Given a potentially-evaluated expression, this visitor visits all
28/// of its potentially-evaluated subexpressions, recursively.
29template<template <typename> class Ptr, typename ImplClass>
30class EvaluatedExprVisitorBase : public StmtVisitorBase<Ptr, ImplClass, void> {
31protected:
32  const ASTContext &Context;
33
34public:
35#define PTR(CLASS) typename Ptr<CLASS>::type
36
37  explicit EvaluatedExprVisitorBase(const ASTContext &Context) : Context(Context) { }
38
39  // Expressions that have no potentially-evaluated subexpressions (but may have
40  // other sub-expressions).
41  void VisitDeclRefExpr(PTR(DeclRefExpr) E) { }
42  void VisitOffsetOfExpr(PTR(OffsetOfExpr) E) { }
43  void VisitUnaryExprOrTypeTraitExpr(PTR(UnaryExprOrTypeTraitExpr) E) { }
44  void VisitExpressionTraitExpr(PTR(ExpressionTraitExpr) E) { }
45  void VisitBlockExpr(PTR(BlockExpr) E) { }
46  void VisitCXXUuidofExpr(PTR(CXXUuidofExpr) E) { }
47  void VisitCXXNoexceptExpr(PTR(CXXNoexceptExpr) E) { }
48
49  void VisitMemberExpr(PTR(MemberExpr) E) {
50    // Only the base matters.
51    return this->Visit(E->getBase());
52  }
53
54  void VisitChooseExpr(PTR(ChooseExpr) E) {
55    // Don't visit either child expression if the condition is dependent.
56    if (E->getCond()->isValueDependent())
57      return;
58    // Only the selected subexpression matters; the other one is not evaluated.
59    return this->Visit(E->getChosenSubExpr());
60  }
61
62  void VisitGenericSelectionExpr(PTR(GenericSelectionExpr) E) {
63    // The controlling expression of a generic selection is not evaluated.
64
65    // Don't visit either child expression if the condition is type-dependent.
66    if (E->isResultDependent())
67      return;
68    // Only the selected subexpression matters; the other subexpressions and the
69    // controlling expression are not evaluated.
70    return this->Visit(E->getResultExpr());
71  }
72
73  void VisitDesignatedInitExpr(PTR(DesignatedInitExpr) E) {
74    // Only the actual initializer matters; the designators are all constant
75    // expressions.
76    return this->Visit(E->getInit());
77  }
78
79  void VisitCXXTypeidExpr(PTR(CXXTypeidExpr) E) {
80    if (E->isPotentiallyEvaluated())
81      return this->Visit(E->getExprOperand());
82  }
83
84  void VisitCallExpr(PTR(CallExpr) CE) {
85    if (!CE->isUnevaluatedBuiltinCall(Context))
86      return static_cast<ImplClass*>(this)->VisitExpr(CE);
87  }
88
89  void VisitLambdaExpr(PTR(LambdaExpr) LE) {
90    // Only visit the capture initializers, and not the body.
91    for (LambdaExpr::const_capture_init_iterator I = LE->capture_init_begin(),
92                                                 E = LE->capture_init_end();
93         I != E; ++I)
94      if (*I)
95        this->Visit(*I);
96  }
97
98  /// \brief The basis case walks all of the children of the statement or
99  /// expression, assuming they are all potentially evaluated.
100  void VisitStmt(PTR(Stmt) S) {
101    for (auto *SubStmt : S->children())
102      if (SubStmt)
103        this->Visit(SubStmt);
104  }
105
106#undef PTR
107};
108
109/// EvaluatedExprVisitor - This class visits 'Expr *'s
110template<typename ImplClass>
111class EvaluatedExprVisitor
112 : public EvaluatedExprVisitorBase<make_ptr, ImplClass> {
113public:
114  explicit EvaluatedExprVisitor(const ASTContext &Context) :
115    EvaluatedExprVisitorBase<make_ptr, ImplClass>(Context) { }
116};
117
118/// ConstEvaluatedExprVisitor - This class visits 'const Expr *'s.
119template<typename ImplClass>
120class ConstEvaluatedExprVisitor
121 : public EvaluatedExprVisitorBase<make_const_ptr, ImplClass> {
122public:
123  explicit ConstEvaluatedExprVisitor(const ASTContext &Context) :
124    EvaluatedExprVisitorBase<make_const_ptr, ImplClass>(Context) { }
125};
126
127}
128
129#endif // LLVM_CLANG_AST_EVALUATEDEXPRVISITOR_H
130