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