1//===--- ParentMap.cpp - Mappings from Stmts to their Parents ---*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9//  This file defines the ParentMap class.
10//
11//===----------------------------------------------------------------------===//
12
13#include "clang/AST/ParentMap.h"
14#include "clang/AST/Decl.h"
15#include "clang/AST/Expr.h"
16#include "clang/AST/ExprCXX.h"
17#include "clang/AST/StmtObjC.h"
18#include "llvm/ADT/DenseMap.h"
19
20using namespace clang;
21
22typedef llvm::DenseMap<Stmt*, Stmt*> MapTy;
23
24enum OpaqueValueMode {
25  OV_Transparent,
26  OV_Opaque
27};
28
29static 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    PseudoObjectExpr *POE = cast<PseudoObjectExpr>(S);
37
38    if (OVMode == OV_Opaque && M[POE->getSyntacticForm()])
39      break;
40
41    // If we are rebuilding the map, clear out any existing state.
42    if (M[POE->getSyntacticForm()])
43      for (Stmt *SubStmt : S->children())
44        M[SubStmt] = nullptr;
45
46    M[POE->getSyntacticForm()] = S;
47    BuildParentMap(M, POE->getSyntacticForm(), OV_Transparent);
48
49    for (PseudoObjectExpr::semantics_iterator I = POE->semantics_begin(),
50                                              E = POE->semantics_end();
51         I != E; ++I) {
52      M[*I] = S;
53      BuildParentMap(M, *I, OV_Opaque);
54    }
55    break;
56  }
57  case Stmt::BinaryConditionalOperatorClass: {
58    assert(OVMode == OV_Transparent && "Should not appear alongside OVEs");
59    BinaryConditionalOperator *BCO = cast<BinaryConditionalOperator>(S);
60
61    M[BCO->getCommon()] = S;
62    BuildParentMap(M, BCO->getCommon(), OV_Transparent);
63
64    M[BCO->getCond()] = S;
65    BuildParentMap(M, BCO->getCond(), OV_Opaque);
66
67    M[BCO->getTrueExpr()] = S;
68    BuildParentMap(M, BCO->getTrueExpr(), OV_Opaque);
69
70    M[BCO->getFalseExpr()] = S;
71    BuildParentMap(M, BCO->getFalseExpr(), OV_Transparent);
72
73    break;
74  }
75  case Stmt::OpaqueValueExprClass: {
76    // FIXME: This isn't correct; it assumes that multiple OpaqueValueExprs
77    // share a single source expression, but in the AST a single
78    // OpaqueValueExpr is shared among multiple parent expressions.
79    // The right thing to do is to give the OpaqueValueExpr its syntactic
80    // parent, then not reassign that when traversing the semantic expressions.
81    OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(S);
82    if (OVMode == OV_Transparent || !M[OVE->getSourceExpr()]) {
83      M[OVE->getSourceExpr()] = S;
84      BuildParentMap(M, OVE->getSourceExpr(), OV_Transparent);
85    }
86    break;
87  }
88  case Stmt::CapturedStmtClass:
89    for (Stmt *SubStmt : S->children()) {
90      if (SubStmt) {
91        M[SubStmt] = S;
92        BuildParentMap(M, SubStmt, OVMode);
93      }
94    }
95    if (Stmt *SubStmt = cast<CapturedStmt>(S)->getCapturedStmt()) {
96      M[SubStmt] = S;
97      BuildParentMap(M, SubStmt, OVMode);
98    }
99    break;
100  default:
101    for (Stmt *SubStmt : S->children()) {
102      if (SubStmt) {
103        M[SubStmt] = S;
104        BuildParentMap(M, SubStmt, OVMode);
105      }
106    }
107    break;
108  }
109}
110
111ParentMap::ParentMap(Stmt *S) : Impl(nullptr) {
112  if (S) {
113    MapTy *M = new MapTy();
114    BuildParentMap(*M, S);
115    Impl = M;
116  }
117}
118
119ParentMap::~ParentMap() {
120  delete (MapTy*) Impl;
121}
122
123void ParentMap::addStmt(Stmt* S) {
124  if (S) {
125    BuildParentMap(*(MapTy*) Impl, S);
126  }
127}
128
129void ParentMap::setParent(const Stmt *S, const Stmt *Parent) {
130  assert(S);
131  assert(Parent);
132  MapTy *M = reinterpret_cast<MapTy *>(Impl);
133  M->insert(std::make_pair(const_cast<Stmt *>(S), const_cast<Stmt *>(Parent)));
134}
135
136Stmt* ParentMap::getParent(Stmt* S) const {
137  MapTy* M = (MapTy*) Impl;
138  return M->lookup(S);
139}
140
141Stmt *ParentMap::getParentIgnoreParens(Stmt *S) const {
142  do { S = getParent(S); } while (S && isa<ParenExpr>(S));
143  return S;
144}
145
146Stmt *ParentMap::getParentIgnoreParenCasts(Stmt *S) const {
147  do {
148    S = getParent(S);
149  }
150  while (S && (isa<ParenExpr>(S) || isa<CastExpr>(S)));
151
152  return S;
153}
154
155Stmt *ParentMap::getParentIgnoreParenImpCasts(Stmt *S) const {
156  do {
157    S = getParent(S);
158  } while (S && isa<Expr>(S) && cast<Expr>(S)->IgnoreParenImpCasts() != S);
159
160  return S;
161}
162
163Stmt *ParentMap::getOuterParenParent(Stmt *S) const {
164  Stmt *Paren = nullptr;
165  while (isa<ParenExpr>(S)) {
166    Paren = S;
167    S = getParent(S);
168  };
169  return Paren;
170}
171
172bool ParentMap::isConsumedExpr(Expr* E) const {
173  Stmt *P = getParent(E);
174  Stmt *DirectChild = E;
175
176  // Ignore parents that don't guarantee consumption.
177  while (P && (isa<ParenExpr>(P) || isa<CastExpr>(P) ||
178               isa<FullExpr>(P))) {
179    DirectChild = P;
180    P = getParent(P);
181  }
182
183  if (!P)
184    return false;
185
186  switch (P->getStmtClass()) {
187    default:
188      return isa<Expr>(P);
189    case Stmt::DeclStmtClass:
190      return true;
191    case Stmt::BinaryOperatorClass: {
192      BinaryOperator *BE = cast<BinaryOperator>(P);
193      // If it is a comma, only the right side is consumed.
194      // If it isn't a comma, both sides are consumed.
195      return BE->getOpcode()!=BO_Comma ||DirectChild==BE->getRHS();
196    }
197    case Stmt::ForStmtClass:
198      return DirectChild == cast<ForStmt>(P)->getCond();
199    case Stmt::WhileStmtClass:
200      return DirectChild == cast<WhileStmt>(P)->getCond();
201    case Stmt::DoStmtClass:
202      return DirectChild == cast<DoStmt>(P)->getCond();
203    case Stmt::IfStmtClass:
204      return DirectChild == cast<IfStmt>(P)->getCond();
205    case Stmt::IndirectGotoStmtClass:
206      return DirectChild == cast<IndirectGotoStmt>(P)->getTarget();
207    case Stmt::SwitchStmtClass:
208      return DirectChild == cast<SwitchStmt>(P)->getCond();
209    case Stmt::ObjCForCollectionStmtClass:
210      return DirectChild == cast<ObjCForCollectionStmt>(P)->getCollection();
211    case Stmt::ReturnStmtClass:
212      return true;
213  }
214}
215
216