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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   if (!S)
     32     return;
     33 
     34   switch (S->getStmtClass()) {
     35   case Stmt::PseudoObjectExprClass: {
     36     assert(OVMode == OV_Transparent && "Should not appear alongside OVEs");
     37     PseudoObjectExpr *POE = cast<PseudoObjectExpr>(S);
     38 
     39     // If we are rebuilding the map, clear out any existing state.
     40     if (M[POE->getSyntacticForm()])
     41       for (Stmt *SubStmt : S->children())
     42         M[SubStmt] = nullptr;
     43 
     44     M[POE->getSyntacticForm()] = S;
     45     BuildParentMap(M, POE->getSyntacticForm(), OV_Transparent);
     46 
     47     for (PseudoObjectExpr::semantics_iterator I = POE->semantics_begin(),
     48                                               E = POE->semantics_end();
     49          I != E; ++I) {
     50       M[*I] = S;
     51       BuildParentMap(M, *I, OV_Opaque);
     52     }
     53     break;
     54   }
     55   case Stmt::BinaryConditionalOperatorClass: {
     56     assert(OVMode == OV_Transparent && "Should not appear alongside OVEs");
     57     BinaryConditionalOperator *BCO = cast<BinaryConditionalOperator>(S);
     58 
     59     M[BCO->getCommon()] = S;
     60     BuildParentMap(M, BCO->getCommon(), OV_Transparent);
     61 
     62     M[BCO->getCond()] = S;
     63     BuildParentMap(M, BCO->getCond(), OV_Opaque);
     64 
     65     M[BCO->getTrueExpr()] = S;
     66     BuildParentMap(M, BCO->getTrueExpr(), OV_Opaque);
     67 
     68     M[BCO->getFalseExpr()] = S;
     69     BuildParentMap(M, BCO->getFalseExpr(), OV_Transparent);
     70 
     71     break;
     72   }
     73   case Stmt::OpaqueValueExprClass: {
     74     // FIXME: This isn't correct; it assumes that multiple OpaqueValueExprs
     75     // share a single source expression, but in the AST a single
     76     // OpaqueValueExpr is shared among multiple parent expressions.
     77     // The right thing to do is to give the OpaqueValueExpr its syntactic
     78     // parent, then not reassign that when traversing the semantic expressions.
     79     OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(S);
     80     if (OVMode == OV_Transparent || !M[OVE->getSourceExpr()]) {
     81       M[OVE->getSourceExpr()] = S;
     82       BuildParentMap(M, OVE->getSourceExpr(), OV_Transparent);
     83     }
     84     break;
     85   }
     86   default:
     87     for (Stmt *SubStmt : S->children()) {
     88       if (SubStmt) {
     89         M[SubStmt] = S;
     90         BuildParentMap(M, SubStmt, OVMode);
     91       }
     92     }
     93     break;
     94   }
     95 }
     96 
     97 ParentMap::ParentMap(Stmt *S) : Impl(nullptr) {
     98   if (S) {
     99     MapTy *M = new MapTy();
    100     BuildParentMap(*M, S);
    101     Impl = M;
    102   }
    103 }
    104 
    105 ParentMap::~ParentMap() {
    106   delete (MapTy*) Impl;
    107 }
    108 
    109 void ParentMap::addStmt(Stmt* S) {
    110   if (S) {
    111     BuildParentMap(*(MapTy*) Impl, S);
    112   }
    113 }
    114 
    115 void ParentMap::setParent(const Stmt *S, const Stmt *Parent) {
    116   assert(S);
    117   assert(Parent);
    118   MapTy *M = reinterpret_cast<MapTy *>(Impl);
    119   M->insert(std::make_pair(const_cast<Stmt *>(S), const_cast<Stmt *>(Parent)));
    120 }
    121 
    122 Stmt* ParentMap::getParent(Stmt* S) const {
    123   MapTy* M = (MapTy*) Impl;
    124   MapTy::iterator I = M->find(S);
    125   return I == M->end() ? nullptr : I->second;
    126 }
    127 
    128 Stmt *ParentMap::getParentIgnoreParens(Stmt *S) const {
    129   do { S = getParent(S); } while (S && isa<ParenExpr>(S));
    130   return S;
    131 }
    132 
    133 Stmt *ParentMap::getParentIgnoreParenCasts(Stmt *S) const {
    134   do {
    135     S = getParent(S);
    136   }
    137   while (S && (isa<ParenExpr>(S) || isa<CastExpr>(S)));
    138 
    139   return S;
    140 }
    141 
    142 Stmt *ParentMap::getParentIgnoreParenImpCasts(Stmt *S) const {
    143   do {
    144     S = getParent(S);
    145   } while (S && isa<Expr>(S) && cast<Expr>(S)->IgnoreParenImpCasts() != S);
    146 
    147   return S;
    148 }
    149 
    150 Stmt *ParentMap::getOuterParenParent(Stmt *S) const {
    151   Stmt *Paren = nullptr;
    152   while (isa<ParenExpr>(S)) {
    153     Paren = S;
    154     S = getParent(S);
    155   };
    156   return Paren;
    157 }
    158 
    159 bool ParentMap::isConsumedExpr(Expr* E) const {
    160   Stmt *P = getParent(E);
    161   Stmt *DirectChild = E;
    162 
    163   // Ignore parents that don't guarantee consumption.
    164   while (P && (isa<ParenExpr>(P) || isa<CastExpr>(P) ||
    165                isa<ExprWithCleanups>(P))) {
    166     DirectChild = P;
    167     P = getParent(P);
    168   }
    169 
    170   if (!P)
    171     return false;
    172 
    173   switch (P->getStmtClass()) {
    174     default:
    175       return isa<Expr>(P);
    176     case Stmt::DeclStmtClass:
    177       return true;
    178     case Stmt::BinaryOperatorClass: {
    179       BinaryOperator *BE = cast<BinaryOperator>(P);
    180       // If it is a comma, only the right side is consumed.
    181       // If it isn't a comma, both sides are consumed.
    182       return BE->getOpcode()!=BO_Comma ||DirectChild==BE->getRHS();
    183     }
    184     case Stmt::ForStmtClass:
    185       return DirectChild == cast<ForStmt>(P)->getCond();
    186     case Stmt::WhileStmtClass:
    187       return DirectChild == cast<WhileStmt>(P)->getCond();
    188     case Stmt::DoStmtClass:
    189       return DirectChild == cast<DoStmt>(P)->getCond();
    190     case Stmt::IfStmtClass:
    191       return DirectChild == cast<IfStmt>(P)->getCond();
    192     case Stmt::IndirectGotoStmtClass:
    193       return DirectChild == cast<IndirectGotoStmt>(P)->getTarget();
    194     case Stmt::SwitchStmtClass:
    195       return DirectChild == cast<SwitchStmt>(P)->getCond();
    196     case Stmt::ReturnStmtClass:
    197       return true;
    198   }
    199 }
    200 
    201