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      1 //===--- ParentMap.cpp - Mappings from Stmts to their Parents ---*- 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 ParentMap class.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "clang/AST/ParentMap.h"
     15 #include "clang/AST/Decl.h"
     16 #include "clang/AST/Expr.h"
     17 #include "clang/AST/ExprCXX.h"
     18 #include "llvm/ADT/DenseMap.h"
     19 
     20 using namespace clang;
     21 
     22 typedef llvm::DenseMap<Stmt*, Stmt*> MapTy;
     23 
     24 enum OpaqueValueMode {
     25   OV_Transparent,
     26   OV_Opaque
     27 };
     28 
     29 static void BuildParentMap(MapTy& M, Stmt* S,
     30                            OpaqueValueMode OVMode = OV_Transparent) {
     31 
     32   switch (S->getStmtClass()) {
     33   case Stmt::PseudoObjectExprClass: {
     34     assert(OVMode == OV_Transparent && "Should not appear alongside OVEs");
     35     PseudoObjectExpr *POE = cast<PseudoObjectExpr>(S);
     36 
     37     // If we are rebuilding the map, clear out any existing state.
     38     if (M[POE->getSyntacticForm()])
     39       for (Stmt::child_range I = S->children(); I; ++I)
     40         M[*I] = nullptr;
     41 
     42     M[POE->getSyntacticForm()] = S;
     43     BuildParentMap(M, POE->getSyntacticForm(), OV_Transparent);
     44 
     45     for (PseudoObjectExpr::semantics_iterator I = POE->semantics_begin(),
     46                                               E = POE->semantics_end();
     47          I != E; ++I) {
     48       M[*I] = S;
     49       BuildParentMap(M, *I, OV_Opaque);
     50     }
     51     break;
     52   }
     53   case Stmt::BinaryConditionalOperatorClass: {
     54     assert(OVMode == OV_Transparent && "Should not appear alongside OVEs");
     55     BinaryConditionalOperator *BCO = cast<BinaryConditionalOperator>(S);
     56 
     57     M[BCO->getCommon()] = S;
     58     BuildParentMap(M, BCO->getCommon(), OV_Transparent);
     59 
     60     M[BCO->getCond()] = S;
     61     BuildParentMap(M, BCO->getCond(), OV_Opaque);
     62 
     63     M[BCO->getTrueExpr()] = S;
     64     BuildParentMap(M, BCO->getTrueExpr(), OV_Opaque);
     65 
     66     M[BCO->getFalseExpr()] = S;
     67     BuildParentMap(M, BCO->getFalseExpr(), OV_Transparent);
     68 
     69     break;
     70   }
     71   case Stmt::OpaqueValueExprClass: {
     72     // FIXME: This isn't correct; it assumes that multiple OpaqueValueExprs
     73     // share a single source expression, but in the AST a single
     74     // OpaqueValueExpr is shared among multiple parent expressions.
     75     // The right thing to do is to give the OpaqueValueExpr its syntactic
     76     // parent, then not reassign that when traversing the semantic expressions.
     77     OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(S);
     78     if (OVMode == OV_Transparent || !M[OVE->getSourceExpr()]) {
     79       M[OVE->getSourceExpr()] = S;
     80       BuildParentMap(M, OVE->getSourceExpr(), OV_Transparent);
     81     }
     82     break;
     83   }
     84   default:
     85     for (Stmt::child_range I = S->children(); I; ++I) {
     86       if (*I) {
     87         M[*I] = S;
     88         BuildParentMap(M, *I, OVMode);
     89       }
     90     }
     91     break;
     92   }
     93 }
     94 
     95 ParentMap::ParentMap(Stmt *S) : Impl(nullptr) {
     96   if (S) {
     97     MapTy *M = new MapTy();
     98     BuildParentMap(*M, S);
     99     Impl = M;
    100   }
    101 }
    102 
    103 ParentMap::~ParentMap() {
    104   delete (MapTy*) Impl;
    105 }
    106 
    107 void ParentMap::addStmt(Stmt* S) {
    108   if (S) {
    109     BuildParentMap(*(MapTy*) Impl, S);
    110   }
    111 }
    112 
    113 void ParentMap::setParent(const Stmt *S, const Stmt *Parent) {
    114   assert(S);
    115   assert(Parent);
    116   MapTy *M = reinterpret_cast<MapTy *>(Impl);
    117   M->insert(std::make_pair(const_cast<Stmt *>(S), const_cast<Stmt *>(Parent)));
    118 }
    119 
    120 Stmt* ParentMap::getParent(Stmt* S) const {
    121   MapTy* M = (MapTy*) Impl;
    122   MapTy::iterator I = M->find(S);
    123   return I == M->end() ? nullptr : I->second;
    124 }
    125 
    126 Stmt *ParentMap::getParentIgnoreParens(Stmt *S) const {
    127   do { S = getParent(S); } while (S && isa<ParenExpr>(S));
    128   return S;
    129 }
    130 
    131 Stmt *ParentMap::getParentIgnoreParenCasts(Stmt *S) const {
    132   do {
    133     S = getParent(S);
    134   }
    135   while (S && (isa<ParenExpr>(S) || isa<CastExpr>(S)));
    136 
    137   return S;
    138 }
    139 
    140 Stmt *ParentMap::getParentIgnoreParenImpCasts(Stmt *S) const {
    141   do {
    142     S = getParent(S);
    143   } while (S && isa<Expr>(S) && cast<Expr>(S)->IgnoreParenImpCasts() != S);
    144 
    145   return S;
    146 }
    147 
    148 Stmt *ParentMap::getOuterParenParent(Stmt *S) const {
    149   Stmt *Paren = nullptr;
    150   while (isa<ParenExpr>(S)) {
    151     Paren = S;
    152     S = getParent(S);
    153   };
    154   return Paren;
    155 }
    156 
    157 bool ParentMap::isConsumedExpr(Expr* E) const {
    158   Stmt *P = getParent(E);
    159   Stmt *DirectChild = E;
    160 
    161   // Ignore parents that don't guarantee consumption.
    162   while (P && (isa<ParenExpr>(P) || isa<CastExpr>(P) ||
    163                isa<ExprWithCleanups>(P))) {
    164     DirectChild = P;
    165     P = getParent(P);
    166   }
    167 
    168   if (!P)
    169     return false;
    170 
    171   switch (P->getStmtClass()) {
    172     default:
    173       return isa<Expr>(P);
    174     case Stmt::DeclStmtClass:
    175       return true;
    176     case Stmt::BinaryOperatorClass: {
    177       BinaryOperator *BE = cast<BinaryOperator>(P);
    178       // If it is a comma, only the right side is consumed.
    179       // If it isn't a comma, both sides are consumed.
    180       return BE->getOpcode()!=BO_Comma ||DirectChild==BE->getRHS();
    181     }
    182     case Stmt::ForStmtClass:
    183       return DirectChild == cast<ForStmt>(P)->getCond();
    184     case Stmt::WhileStmtClass:
    185       return DirectChild == cast<WhileStmt>(P)->getCond();
    186     case Stmt::DoStmtClass:
    187       return DirectChild == cast<DoStmt>(P)->getCond();
    188     case Stmt::IfStmtClass:
    189       return DirectChild == cast<IfStmt>(P)->getCond();
    190     case Stmt::IndirectGotoStmtClass:
    191       return DirectChild == cast<IndirectGotoStmt>(P)->getTarget();
    192     case Stmt::SwitchStmtClass:
    193       return DirectChild == cast<SwitchStmt>(P)->getCond();
    194     case Stmt::ReturnStmtClass:
    195       return true;
    196   }
    197 }
    198 
    199