llvm-project

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//===--- ParentMap.cpp - Mappings from Stmts to their Parents ---*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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//  This file defines the ParentMap class.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/AST/ParentMap.h"
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#include "clang/AST/Decl.h"
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#include "clang/AST/Expr.h"
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#include "clang/AST/ExprCXX.h"
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#include "clang/AST/StmtObjC.h"
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#include "llvm/ADT/DenseMap.h"
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using namespace clang;
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typedef llvm::DenseMap<Stmt*, Stmt*> MapTy;
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enum OpaqueValueMode {
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  OV_Transparent,
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  OV_Opaque
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};
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static void BuildParentMap(MapTy& M, Stmt* S,
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                           OpaqueValueMode OVMode = OV_Transparent) {
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  if (!S)
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    return;
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  switch (S->getStmtClass()) {
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  case Stmt::PseudoObjectExprClass: {
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    PseudoObjectExpr *POE = cast<PseudoObjectExpr>(S);
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    if (OVMode == OV_Opaque && M[POE->getSyntacticForm()])
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      break;
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    // If we are rebuilding the map, clear out any existing state.
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    if (M[POE->getSyntacticForm()])
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      for (Stmt *SubStmt : S->children())
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        M[SubStmt] = nullptr;
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    M[POE->getSyntacticForm()] = S;
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    BuildParentMap(M, POE->getSyntacticForm(), OV_Transparent);
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    for (PseudoObjectExpr::semantics_iterator I = POE->semantics_begin(),
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                                              E = POE->semantics_end();
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         I != E; ++I) {
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      M[*I] = S;
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      BuildParentMap(M, *I, OV_Opaque);
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    }
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    break;
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  }
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  case Stmt::BinaryConditionalOperatorClass: {
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    assert(OVMode == OV_Transparent && "Should not appear alongside OVEs");
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    BinaryConditionalOperator *BCO = cast<BinaryConditionalOperator>(S);
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    M[BCO->getCommon()] = S;
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    BuildParentMap(M, BCO->getCommon(), OV_Transparent);
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    M[BCO->getCond()] = S;
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    BuildParentMap(M, BCO->getCond(), OV_Opaque);
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    M[BCO->getTrueExpr()] = S;
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    BuildParentMap(M, BCO->getTrueExpr(), OV_Opaque);
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    M[BCO->getFalseExpr()] = S;
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    BuildParentMap(M, BCO->getFalseExpr(), OV_Transparent);
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    break;
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  }
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  case Stmt::OpaqueValueExprClass: {
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    // FIXME: This isn't correct; it assumes that multiple OpaqueValueExprs
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    // share a single source expression, but in the AST a single
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    // OpaqueValueExpr is shared among multiple parent expressions.
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    // The right thing to do is to give the OpaqueValueExpr its syntactic
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    // parent, then not reassign that when traversing the semantic expressions.
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    OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(S);
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    if (OVMode == OV_Transparent || !M[OVE->getSourceExpr()]) {
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      M[OVE->getSourceExpr()] = S;
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      BuildParentMap(M, OVE->getSourceExpr(), OV_Transparent);
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    }
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    break;
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  }
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  case Stmt::CapturedStmtClass:
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    for (Stmt *SubStmt : S->children()) {
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      if (SubStmt) {
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        M[SubStmt] = S;
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        BuildParentMap(M, SubStmt, OVMode);
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      }
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    }
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    if (Stmt *SubStmt = cast<CapturedStmt>(S)->getCapturedStmt()) {
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      M[SubStmt] = S;
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      BuildParentMap(M, SubStmt, OVMode);
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    }
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    break;
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  default:
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    for (Stmt *SubStmt : S->children()) {
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      if (SubStmt) {
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        M[SubStmt] = S;
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        BuildParentMap(M, SubStmt, OVMode);
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      }
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    }
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    break;
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  }
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}
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ParentMap::ParentMap(Stmt *S) : Impl(nullptr) {
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  if (S) {
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    MapTy *M = new MapTy();
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    BuildParentMap(*M, S);
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    Impl = M;
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  }
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}
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ParentMap::~ParentMap() {
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  delete (MapTy*) Impl;
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}
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void ParentMap::addStmt(Stmt* S) {
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  if (S) {
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    BuildParentMap(*(MapTy*) Impl, S);
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  }
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}
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void ParentMap::setParent(const Stmt *S, const Stmt *Parent) {
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  assert(S);
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  assert(Parent);
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  MapTy *M = reinterpret_cast<MapTy *>(Impl);
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  M->insert(std::make_pair(const_cast<Stmt *>(S), const_cast<Stmt *>(Parent)));
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}
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Stmt* ParentMap::getParent(Stmt* S) const {
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  MapTy* M = (MapTy*) Impl;
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  return M->lookup(S);
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}
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Stmt *ParentMap::getParentIgnoreParens(Stmt *S) const {
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  do {
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    S = getParent(S);
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  } while (isa_and_nonnull<ParenExpr>(S));
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  return S;
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}
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Stmt *ParentMap::getParentIgnoreParenCasts(Stmt *S) const {
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  do {
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    S = getParent(S);
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  }
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  while (S && (isa<ParenExpr>(S) || isa<CastExpr>(S)));
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  return S;
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}
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Stmt *ParentMap::getParentIgnoreParenImpCasts(Stmt *S) const {
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  do {
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    S = getParent(S);
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  } while (isa_and_nonnull<Expr>(S) &&
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           cast<Expr>(S)->IgnoreParenImpCasts() != S);
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  return S;
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}
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Stmt *ParentMap::getOuterParenParent(Stmt *S) const {
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  Stmt *Paren = nullptr;
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  while (isa<ParenExpr>(S)) {
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    Paren = S;
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    S = getParent(S);
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  };
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  return Paren;
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}
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bool ParentMap::isConsumedExpr(Expr* E) const {
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  Stmt *P = getParent(E);
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  Stmt *DirectChild = E;
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  // Ignore parents that don't guarantee consumption.
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  while (P && (isa<ParenExpr>(P) || isa<CastExpr>(P) ||
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               isa<FullExpr>(P))) {
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    DirectChild = P;
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    P = getParent(P);
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  }
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  if (!P)
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    return false;
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  switch (P->getStmtClass()) {
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    default:
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      return isa<Expr>(P);
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    case Stmt::DeclStmtClass:
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      return true;
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    case Stmt::BinaryOperatorClass: {
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      BinaryOperator *BE = cast<BinaryOperator>(P);
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      // If it is a comma, only the right side is consumed.
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      // If it isn't a comma, both sides are consumed.
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      return BE->getOpcode()!=BO_Comma ||DirectChild==BE->getRHS();
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    }
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    case Stmt::ForStmtClass:
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      return DirectChild == cast<ForStmt>(P)->getCond();
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    case Stmt::WhileStmtClass:
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      return DirectChild == cast<WhileStmt>(P)->getCond();
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    case Stmt::DoStmtClass:
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      return DirectChild == cast<DoStmt>(P)->getCond();
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    case Stmt::IfStmtClass:
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      return DirectChild == cast<IfStmt>(P)->getCond();
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    case Stmt::IndirectGotoStmtClass:
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      return DirectChild == cast<IndirectGotoStmt>(P)->getTarget();
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    case Stmt::SwitchStmtClass:
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      return DirectChild == cast<SwitchStmt>(P)->getCond();
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    case Stmt::ObjCForCollectionStmtClass:
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      return DirectChild == cast<ObjCForCollectionStmt>(P)->getCollection();
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    case Stmt::ReturnStmtClass:
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      return true;
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  }
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}
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