C++ CAstStatement::GetNext方法代码示例

CTacAddr* CAstStatIf::ToTac(CCodeBlock *cb, CTacLabel *next)
{
  CTacLabel* truelabel = cb->CreateLabel("if_true"); // true label
  CTacLabel* falselabel = cb->CreateLabel("if_false"); // false label
  _cond->ToTac(cb, truelabel, falselabel); // calculate condition

  CAstStatement *s = _ifBody;
  cb->AddInstr(truelabel); // install true label
  while(s != NULL) { // TAC of ifBody
    CTacLabel* tempnext = cb->CreateLabel();
    s->ToTac(cb, tempnext);
    cb->AddInstr(tempnext);
    s = s->GetNext();
  }
  cb->AddInstr(new CTacInstr(opGoto, next)); // skip to next

  s = _elseBody;
  cb->AddInstr(falselabel); // install false label
  while(s != NULL) { // TAC of elseBody
    CTacLabel* tempnext = cb->CreateLabel();
    s->ToTac(cb, tempnext);
    cb->AddInstr(tempnext);
    s = s->GetNext();
  }

  cb->AddInstr(new CTacInstr(opGoto, next)); // goto next

  return NULL;
}

ostream& CAstStatIf::print(ostream &out, int indent) const
{
  string ind(indent, ' ');

  out << ind << "if cond" << endl;
  _cond->print(out, indent+2);
  out << ind << "if-body" << endl;
  if (_ifBody != NULL) {
    CAstStatement *s = _ifBody;
    do {
      s->print(out, indent+2);
      s = s->GetNext();
    } while (s != NULL);
  } else out << ind << "  empty." << endl;
  out << ind << "else-body" << endl;
  if (_elseBody != NULL) {
    CAstStatement *s = _elseBody;
    do {
      s->print(out, indent+2);
      s = s->GetNext();
    } while (s != NULL);
  } else out << ind << "  empty." << endl;

  return out;
}

bool CAstStatIf::TypeCheck(CToken *t, string *msg) const
{
  CAstExpression *cond = GetCondition();
  bool result = true;
  
  if (!cond->TypeCheck(t, msg)) return false;
  if (cond->GetType() != CTypeManager::Get()->GetBool()) {
    if (t != NULL) *t = cond->GetToken();
    if (msg != NULL) *msg = "boolean expression expected.";
    return false;
  }

  try {
    CAstStatement *ifBody = GetIfBody();
    CAstStatement *elseBody = GetElseBody();
    
    while (result && (ifBody != NULL)) {
      result = ifBody->TypeCheck(t, msg);
      ifBody = ifBody->GetNext();
    }
    
    while (result && (elseBody != NULL)) {
      result = elseBody->TypeCheck(t, msg);
      elseBody = elseBody->GetNext();
    }
  } catch (...) {
    result = false;
  }
  
  return result;
}

void CAstScope::toDot(ostream &out, int indent) const
{
  string ind(indent, ' ');

  CAstNode::toDot(out, indent);

  CAstStatement *s = GetStatementSequence();
  if (s != NULL) {
    string prev = dotID();
    do {
      s->toDot(out, indent);
      out << ind << prev << " -> " << s->dotID() << " [style=dotted];" << endl;
      prev = s->dotID();
      s = s->GetNext();
    } while (s != NULL);
  }

  vector<CAstScope*>::const_iterator it = _children.begin();
  while (it != _children.end()) {
    CAstScope *s = *it++;
    s->toDot(out, indent);
    out << ind << dotID() << " -> " << s->dotID() << ";" << endl;
  }

}

CTacAddr* CAstStatWhile::ToTac(CCodeBlock *cb, CTacLabel *next)
{
  assert(cb != NULL && next != NULL);
    
  CAstExpression *cond = GetCondition();
  CAstStatement *body = GetBody();
  
  CTacLabel *while_cond = cb->CreateLabel("while_cond");
  CTacLabel *c_true = cb->CreateLabel("while_body");

  // while condition begins
  cb->AddInstr(while_cond);
  CTacAddr *tCond = cond->ToTac(cb, c_true, next);
  if(dynamic_cast<CAstDesignator*>(cond)) { // if cond is a single boolean
    cb->AddInstr(new CTacInstr(opEqual, c_true, tCond, new CTacConst(1)));
    cb->AddInstr(new CTacInstr(opGoto, next));
  }

  // while body starts..
  cb->AddInstr(c_true);
  while(body) {
    CTacLabel *while_next = cb->CreateLabel("while_next");
    body->ToTac(cb, while_next);
    cb->AddInstr(while_next);
    body = body->GetNext();
  }

  cb->AddInstr(new CTacInstr(opGoto, while_cond));
  
  return NULL;
}

bool CAstStatIf::TypeCheck(CToken *t, string *msg) const
{
  if(!_cond->TypeCheck(t, msg)) return false; // Do TypeCheck on condition expression
  if(!_cond->GetType()->IsBoolean()) {
    if(t != NULL) *t = _cond->GetToken();
    if(msg != NULL) *msg = "boolean expression expected.";
    return false;
  }
  bool result = true;
  CAstStatement *s = _ifBody;
  while(result && (s != NULL)) { // Do TypeCheck on all ifBody-statements
    result = s->TypeCheck(t, msg);
    s = s->GetNext();
  }

  s = _elseBody;
  while(result && (s != NULL)) { // Do TypeCheck on all elseBody-statements
    result = s->TypeCheck(t, msg);
    s = s->GetNext();
  }

  return result;
}