Port to C++11 nullptr keyword

Performed using modernize-use-nullptr from clang-tidy.

https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-nullptr.html

src/ComputingTasks.cc

@@ -3880,8 +3880,8 @@ BasicPriorStatement::checkPass(ModFileStructure &mod_file_struct, WarningConsoli
     }
 
   auto it_stdev = options_list.num_options.find("stdev");
-  if ((it_stdev == options_list.num_options.end() && variance == NULL)
-      || (it_stdev != options_list.num_options.end() && variance != NULL))
+  if ((it_stdev == options_list.num_options.end() && variance == nullptr)
+      || (it_stdev != options_list.num_options.end() && variance != nullptr))
     {
       cerr << "ERROR: You must pass exactly one of stdev and variance to the prior statement." << endl;
       exit(EXIT_FAILURE);
@@ -3973,7 +3973,7 @@ BasicPriorStatement::writeJsonPriorOutput(ostream &output) const
          << ", \"subsample\": \"" << subsample_name << "\""
          << ", ";
   writeJsonShape(output);
-  if (variance != NULL)
+  if (variance != nullptr)
     {
       output << ", \"variance\": \"";
       variance->writeJsonOutput(output, {}, {});

src/ConfigFile.cc

@@ -122,7 +122,7 @@ ConfigFile::getConfigFileInfo(const string &config_file)
           defaultConfigFile += "\\dynare.ini";
         }
 #else
-      if (getenv("HOME") == NULL)
+      if (getenv("HOME") == nullptr)
         {
           if (parallel || parallel_test)
             cerr << "ERROR: ";

src/DataTree.cc

@@ -95,7 +95,7 @@ DataTree::AddPlus(expr_t iArg1, expr_t iArg2)
     {
       // Simplify x+(-y) in x-y
       auto *uarg2 = dynamic_cast<UnaryOpNode *>(iArg2);
-      if (uarg2 != NULL && uarg2->get_op_code() == oUminus)
+      if (uarg2 != nullptr && uarg2->get_op_code() == oUminus)
         return AddMinus(iArg1, uarg2->get_arg());
 
       // To treat commutativity of "+"
@@ -138,7 +138,7 @@ DataTree::AddUMinus(expr_t iArg1)
     {
       // Simplify -(-x) in x
       auto *uarg = dynamic_cast<UnaryOpNode *>(iArg1);
-      if (uarg != NULL && uarg->get_op_code() == oUminus)
+      if (uarg != nullptr && uarg->get_op_code() == oUminus)
         return uarg->get_arg();
 
       return AddUnaryOp(oUminus, iArg1);

src/DataTree.hh

@@ -337,7 +337,7 @@ DataTree::AddUnaryOp(UnaryOpcode op_code, expr_t arg, int arg_exp_info_set, int
   // Try to reduce to a constant
   // Case where arg is a constant and op_code == oUminus (i.e. we're adding a negative constant) is skipped
   auto *carg = dynamic_cast<NumConstNode *>(arg);
-  if (op_code != oUminus || carg == NULL)
+  if (op_code != oUminus || carg == nullptr)
     {
       try
         {

src/DynamicModel.cc

@@ -215,7 +215,7 @@ DynamicModel::writeModelEquationsOrdered_M(const string &dynamic_basename) const
 {
   string tmp_s, sps;
   ostringstream tmp_output, tmp1_output, global_output;
-  expr_t lhs = NULL, rhs = NULL;
+  expr_t lhs = nullptr, rhs = nullptr;
   BinaryOpNode *eq_node;
   ostringstream Ufoss;
   vector<string> Uf(symbol_table.endo_nbr(), "");
@@ -457,7 +457,7 @@ DynamicModel::writeModelEquationsOrdered_M(const string &dynamic_basename) const
               output << "  " << "% //Temporary variables" << endl;
               for (auto it : v_temporary_terms[block][i])
                 {
-                  if (dynamic_cast<AbstractExternalFunctionNode *>(it) != NULL)
+                  if (dynamic_cast<AbstractExternalFunctionNode *>(it) != nullptr)
                     it->writeExternalFunctionOutput(output, local_output_type, tt2, temporary_terms_idxs, tef_terms);
 
                   output << "  " <<  sps;
@@ -1063,7 +1063,7 @@ DynamicModel::writeModelEquationsCode_Block(string &file_name, const string &bin
   ostringstream tmp_output;
   ofstream code_file;
   unsigned int instruction_number = 0;
-  expr_t lhs = NULL, rhs = NULL;
+  expr_t lhs = nullptr, rhs = nullptr;
   BinaryOpNode *eq_node;
   Uff Uf[symbol_table.endo_nbr()];
   map<expr_t, int> reference_count;
@@ -1198,7 +1198,7 @@ DynamicModel::writeModelEquationsCode_Block(string &file_name, const string &bin
             {
               for (auto it : v_temporary_terms[block][i])
                 {
-                  if (dynamic_cast<AbstractExternalFunctionNode *>(it) != NULL)
+                  if (dynamic_cast<AbstractExternalFunctionNode *>(it) != nullptr)
                     it->compileExternalFunctionOutput(code_file, instruction_number, false, tt2, map_idx, true, false, tef_terms);
 
                   FNUMEXPR_ fnumexpr(TemporaryTerm, (int)(map_idx.find(it->idx)->second));
@@ -1266,7 +1266,7 @@ DynamicModel::writeModelEquationsCode_Block(string &file_name, const string &bin
               variable_ID = getBlockVariableID(block, i);
               equation_ID = getBlockEquationID(block, i);
               feedback_variables.push_back(variable_ID);
-              Uf[equation_ID].Ufl = NULL;
+              Uf[equation_ID].Ufl = nullptr;
               goto end;
             default:
             end:
@@ -1337,7 +1337,7 @@ DynamicModel::writeModelEquationsCode_Block(string &file_name, const string &bin
                           Uf[eqr].Ufl->pNext = (Uff_l *) malloc(sizeof(Uff_l));
                           Uf[eqr].Ufl = Uf[eqr].Ufl->pNext;
                         }
-                      Uf[eqr].Ufl->pNext = NULL;
+                      Uf[eqr].Ufl->pNext = nullptr;
                       Uf[eqr].Ufl->u = count_u;
                       Uf[eqr].Ufl->var = varr;
                       Uf[eqr].Ufl->lag = lag;
@@ -3742,7 +3742,7 @@ DynamicModel::getUndiffLHSForPac(vector<int> &lhs, vector<expr_t> &lhs_expr_t, v
 
       bool printerr = false;
       ExprNode::subst_table_t::const_iterator it1;
-      expr_t node = NULL;
+      expr_t node = nullptr;
       expr_t aux_var = lhs_expr_t.at(i);
       for (it1 = diff_subst_table.begin(); it1 != diff_subst_table.end(); it1++)
         if (it1->second == aux_var)
@@ -3751,7 +3751,7 @@ DynamicModel::getUndiffLHSForPac(vector<int> &lhs, vector<expr_t> &lhs_expr_t, v
             break;
           }
 
-      if (node == NULL)
+      if (node == nullptr)
         {
           cerr << "Unexpected error encountered." << endl;
           exit(EXIT_FAILURE);
@@ -3837,7 +3837,7 @@ DynamicModel::substitutePacExpectation()
   for (auto & equation : equations)
     {
       auto *substeq = dynamic_cast<BinaryOpNode *>(equation->substitutePacExpectation(subst_table));
-      assert(substeq != NULL);
+      assert(substeq != nullptr);
       equation = substeq;
     }
 
@@ -4507,7 +4507,7 @@ DynamicModel::computeRamseyPolicyFOCs(const StaticModel &static_model, const boo
   for (i = 0; i < (int) equations.size(); i++)
     {
       auto *substeq = dynamic_cast<BinaryOpNode *>(equations[i]->addMultipliersToConstraints(i));
-      assert(substeq != NULL);
+      assert(substeq != nullptr);
       equations[i] = substeq;
     }
   if (!nopreprocessoroutput)
@@ -4544,7 +4544,7 @@ DynamicModel::computeRamseyPolicyFOCs(const StaticModel &static_model, const boo
   for (i = 0; i < (int) equations.size(); i++)
     for (int lag = -max_eq_lag; lag <= max_eq_lead; lag++)
       {
-        expr_t dfpower = NULL;
+        expr_t dfpower = nullptr;
         std::stringstream lagstream;
         lagstream << abs(lag);
         if (lag < 0)
@@ -5264,7 +5264,7 @@ DynamicModel::substituteLeadLagInternal(aux_var_t type, bool deterministic_model
           exit(EXIT_FAILURE);
         }
       auto *substeq = dynamic_cast<BinaryOpNode *>(subst);
-      assert(substeq != NULL);
+      assert(substeq != nullptr);
       equation = substeq;
     }
 
@@ -5297,7 +5297,7 @@ DynamicModel::substituteLeadLagInternal(aux_var_t type, bool deterministic_model
           exit(EXIT_FAILURE);
         }
       auto *substeq = dynamic_cast<BinaryOpNode *>(subst);
-      assert(substeq != NULL);
+      assert(substeq != nullptr);
       aux_equation = substeq;
     }
 
@@ -5330,7 +5330,7 @@ DynamicModel::substituteLeadLagInternal(aux_var_t type, bool deterministic_model
           exit(EXIT_FAILURE);
         }
       auto *substeq = dynamic_cast<BinaryOpNode *>(subst);
-      assert(substeq != NULL);
+      assert(substeq != nullptr);
       diff_aux_equation = substeq;
     }
 
@@ -5404,7 +5404,7 @@ DynamicModel::substituteUnaryOps(StaticModel &static_model)
     {
       auto *substeq = dynamic_cast<BinaryOpNode *>(equation->
                                                            substituteUnaryOpNodes(static_model, nodes, subst_table, neweqs));
-      assert(substeq != NULL);
+      assert(substeq != nullptr);
       equation = substeq;
     }
 
@@ -5439,7 +5439,7 @@ DynamicModel::substituteDiff(StaticModel &static_model, ExprNode::subst_table_t
     {
       auto *substeq = dynamic_cast<BinaryOpNode *>(equation->
                                                            substituteDiff(static_model, diff_table, diff_subst_table, neweqs));
-      assert(substeq != NULL);
+      assert(substeq != nullptr);
       equation = substeq;
     }
 
@@ -5473,7 +5473,7 @@ DynamicModel::substituteExpectation(bool partial_information_model)
   for (auto & equation : equations)
     {
       auto *substeq = dynamic_cast<BinaryOpNode *>(equation->substituteExpectation(subst_table, neweqs, partial_information_model));
-      assert(substeq != NULL);
+      assert(substeq != nullptr);
       equation = substeq;
     }
 
@@ -5502,7 +5502,7 @@ DynamicModel::transformPredeterminedVariables()
   for (auto & equation : equations)
     {
       auto *substeq = dynamic_cast<BinaryOpNode *>(equation->decreaseLeadsLagsPredeterminedVariables());
-      assert(substeq != NULL);
+      assert(substeq != nullptr);
       equation = substeq;
     }
 }
@@ -5516,14 +5516,14 @@ DynamicModel::detrendEquations()
     for (auto & equation : equations)
       {
         auto *substeq = dynamic_cast<BinaryOpNode *>(equation->detrend(it->first, it->second.first, it->second.second));
-        assert(substeq != NULL);
+        assert(substeq != nullptr);
         equation = dynamic_cast<BinaryOpNode *>(substeq);
       }
 
   for (auto & equation : equations)
     {
       BinaryOpNode *substeq = dynamic_cast<BinaryOpNode *>(equation->removeTrendLeadLag(trend_symbols_map));
-      assert(substeq != NULL);
+      assert(substeq != nullptr);
       equation = dynamic_cast<BinaryOpNode *>(substeq);
     }
 }
@@ -5534,7 +5534,7 @@ DynamicModel::removeTrendVariableFromEquations()
   for (auto & equation : equations)
     {
       auto *substeq = dynamic_cast<BinaryOpNode *>(equation->replaceTrendVar());
-      assert(substeq != NULL);
+      assert(substeq != nullptr);
       equation = dynamic_cast<BinaryOpNode *>(substeq);
     }
 }
@@ -5553,7 +5553,7 @@ DynamicModel::fillEvalContext(eval_context_t &eval_context) const
     {
       assert(aux_equation->get_op_code() == oEqual);
       auto *auxvar = dynamic_cast<VariableNode *>(aux_equation->get_arg1());
-      assert(auxvar != NULL);
+      assert(auxvar != nullptr);
       try
         {
           double val = aux_equation->get_arg2()->eval(eval_context);
@@ -5604,7 +5604,7 @@ void
 DynamicModel::addStaticOnlyEquation(expr_t eq, int lineno, const vector<pair<string, string> > &eq_tags)
 {
   auto *beq = dynamic_cast<BinaryOpNode *>(eq);
-  assert(beq != NULL && beq->get_op_code() == oEqual);
+  assert(beq != nullptr && beq->get_op_code() == oEqual);
 
   vector<pair<string, string> > soe_eq_tags;
   for (const auto & eq_tag : eq_tags)

src/ModFile.cc

@@ -382,7 +382,7 @@ ModFile::transformPass(bool nostrict, bool stochastic, bool compute_xrefs, const
        it != statements.end(); it++)
     {
       auto *vms = dynamic_cast<VarModelStatement *>(*it);
-      if (vms != NULL)
+      if (vms != nullptr)
         {
           string var_model_name;
           vms->getVarModelInfo(var_model_name, var_model_info_var_expectation, var_model_eq_tags);
@@ -404,7 +404,7 @@ ModFile::transformPass(bool nostrict, bool stochastic, bool compute_xrefs, const
                       make_pair(make_pair(max_lag, nonstationary), eqnumber));
         }
       auto *pms = dynamic_cast<PacModelStatement *>(*it);
-      if (pms != NULL)
+      if (pms != nullptr)
          {
            pair<string, pair<string, pair<string, pair<int, map<string, int> > > > >
              pac_model_info_pac_expectation;
@@ -459,14 +459,14 @@ ModFile::transformPass(bool nostrict, bool stochastic, bool compute_xrefs, const
   mod_file_struct.orig_eq_nbr = dynamic_model.equation_number();
   if (mod_file_struct.ramsey_model_present)
     {
-      StaticModel *planner_objective = NULL;
+      StaticModel *planner_objective = nullptr;
       for (auto & statement : statements)
         {
           auto *pos = dynamic_cast<PlannerObjectiveStatement *>(statement);
-          if (pos != NULL)
+          if (pos != nullptr)
             planner_objective = pos->getPlannerObjective();
         }
-      assert(planner_objective != NULL);
+      assert(planner_objective != nullptr);
 
       /*
         clone the model then clone the new equations back to the original because
@@ -524,7 +524,7 @@ ModFile::transformPass(bool nostrict, bool stochastic, bool compute_xrefs, const
        it != statements.end(); it++)
     {
       auto *vms = dynamic_cast<VarModelStatement *>(*it);
-      if (vms != NULL)
+      if (vms != nullptr)
         {
           string var_model_name;
           vms->getVarModelInfo(var_model_name, var_model_info_var_expectation, var_model_eq_tags);
@@ -598,7 +598,7 @@ ModFile::transformPass(bool nostrict, bool stochastic, bool compute_xrefs, const
     for (auto & statement : statements)
       {
         auto *rps = dynamic_cast<RamseyPolicyStatement *>(statement);
-        if (rps != NULL)
+        if (rps != nullptr)
           rps->checkRamseyPolicyList();
       }
 
@@ -989,7 +989,7 @@ ModFile::writeOutputFiles(const string &basename, bool clear_all, bool clear_glo
       /* Special treatment for initval block: insert initial values for the
          auxiliary variables and initialize exo det */
       auto *ivs = dynamic_cast<InitValStatement *>(statement);
-      if (ivs != NULL)
+      if (ivs != nullptr)
         {
           static_model.writeAuxVarInitval(mOutputFile, oMatlabOutsideModel);
           ivs->writeOutputPostInit(mOutputFile);
@@ -997,7 +997,7 @@ ModFile::writeOutputFiles(const string &basename, bool clear_all, bool clear_glo
 
       // Special treatment for endval block: insert initial values for the auxiliary variables
       auto *evs = dynamic_cast<EndValStatement *>(statement);
-      if (evs != NULL)
+      if (evs != nullptr)
         static_model.writeAuxVarInitval(mOutputFile, oMatlabOutsideModel);
 
       // Special treatment for load params and steady state statement: insert initial values for the auxiliary variables
@@ -1007,7 +1007,7 @@ ModFile::writeOutputFiles(const string &basename, bool clear_all, bool clear_glo
 
       // Special treatement for Var Models
       auto *vms = dynamic_cast<VarModelStatement *>(statement);
-      if (vms != NULL)
+      if (vms != nullptr)
         vms->createVarModelMFunction(mOutputFile, dynamic_model.getVarExpectationFunctionsToWrite());
     }
 

src/ModelTree.cc

@@ -204,7 +204,7 @@ ModelTree::computeNonSingularNormalization(jacob_map_t &contemporaneous_jacobian
               if (static_jacobian.find(make_pair(it->first.first, it->first.second)) == static_jacobian.end())
                 static_jacobian[make_pair(it->first.first, it->first.second)] = 0;
               if (dynamic_jacobian.find(make_pair(0, make_pair(it->first.first, it->first.second))) == dynamic_jacobian.end())
-                dynamic_jacobian[make_pair(0, make_pair(it->first.first, it->first.second))] = 0;
+                dynamic_jacobian[make_pair(0, make_pair(it->first.first, it->first.second))] = nullptr;
               if (contemporaneous_jacobian.find(make_pair(it->first.first, it->first.second)) == contemporaneous_jacobian.end())
                 contemporaneous_jacobian[make_pair(it->first.first, it->first.second)] = 0;
               try
@@ -235,7 +235,7 @@ ModelTree::computeNormalizedEquations(multimap<int, int> &endo2eqs) const
   for (size_t i = 0; i < equations.size(); i++)
     {
       auto *lhs = dynamic_cast<VariableNode *>(equations[i]->get_arg1());
-      if (lhs == NULL)
+      if (lhs == nullptr)
         continue;
 
       int symb_id = lhs->get_symb_id();
@@ -1224,7 +1224,7 @@ ModelTree::writeTemporaryTerms(const temporary_terms_t &tt,
   for (auto it = tt.begin();
        it != tt.end(); it++)
     {
-      if (dynamic_cast<AbstractExternalFunctionNode *>(*it) != NULL)
+      if (dynamic_cast<AbstractExternalFunctionNode *>(*it) != nullptr)
         (*it)->writeExternalFunctionOutput(output, output_type, tt2, tt_idxs, tef_terms);
 
       if (IS_C(output_type))
@@ -1257,7 +1257,7 @@ ModelTree::writeJsonTemporaryTerms(const temporary_terms_t &tt, const temporary_
   for (auto it : tt)
     if (ttm1.find(it) == ttm1.end())
       {
-        if (dynamic_cast<AbstractExternalFunctionNode *>(it) != NULL)
+        if (dynamic_cast<AbstractExternalFunctionNode *>(it) != nullptr)
           {
             if (wrote_term)
               output << ", ";
@@ -1429,7 +1429,7 @@ ModelTree::compileTemporaryTerms(ostream &code_file, unsigned int &instruction_n
   deriv_node_temp_terms_t tef_terms;
   for (auto it : tt)
     {
-      if (dynamic_cast<AbstractExternalFunctionNode *>(it) != NULL)
+      if (dynamic_cast<AbstractExternalFunctionNode *>(it) != nullptr)
         {
           it->compileExternalFunctionOutput(code_file, instruction_number, false, tt2, map_idx, dynamic, steady_dynamic, tef_terms);
         }
@@ -1734,7 +1734,7 @@ void
 ModelTree::addEquation(expr_t eq, int lineno)
 {
   auto *beq = dynamic_cast<BinaryOpNode *>(eq);
-  assert(beq != NULL && beq->get_op_code() == oEqual);
+  assert(beq != nullptr && beq->get_op_code() == oEqual);
 
   equations.push_back(beq);
   equations_lineno.push_back(lineno);
@@ -1753,7 +1753,7 @@ void
 ModelTree::addAuxEquation(expr_t eq)
 {
   auto *beq = dynamic_cast<BinaryOpNode *>(eq);
-  assert(beq != NULL && beq->get_op_code() == oEqual);
+  assert(beq != nullptr && beq->get_op_code() == oEqual);
 
   aux_equations.push_back(beq);
 }

src/NumericalConstants.cc

@@ -37,7 +37,7 @@ NumericalConstants::AddNonNegativeConstant(const string &iConst)
   mNumericalConstants.push_back(iConst);
   numConstantsIndex[iConst] = id;
 
-  double val = strtod(iConst.c_str(), NULL);
+  double val = strtod(iConst.c_str(), nullptr);
 
   /* Note that we allow underflows (will be converted to 0) and overflows (will
      be converted to Inf), as MATLAB and Octave do. */

src/NumericalInitialization.cc

@@ -495,7 +495,7 @@ HomotopyStatement::writeOutput(ostream &output, const string &basename, bool min
       const int tsid = symbol_table.getTypeSpecificID(symb_id) + 1;
 
       output << "options_.homotopy_values = vertcat(options_.homotopy_values, [ " << type << ", " << tsid << ", ";
-      if (expression1 != NULL)
+      if (expression1 != nullptr)
         expression1->writeOutput(output);
       else
         output << "NaN";

src/ParsingDriver.cc

@@ -187,13 +187,13 @@ ParsingDriver::declare_symbol(const string *name, SymbolType type, const string
 {
   try
     {
-      if (tex_name == NULL && partition_value == NULL)
+      if (tex_name == nullptr && partition_value == nullptr)
         mod_file->symbol_table.addSymbol(*name, type);
       else
-        if (tex_name == NULL)
+        if (tex_name == nullptr)
           mod_file->symbol_table.addSymbol(*name, type, "", partition_value);
-        else if (partition_value == NULL)
-          mod_file->symbol_table.addSymbol(*name, type, *tex_name, NULL);
+        else if (partition_value == nullptr)
+          mod_file->symbol_table.addSymbol(*name, type, *tex_name, nullptr);
         else
           mod_file->symbol_table.addSymbol(*name, type, *tex_name, partition_value);
     }
@@ -211,9 +211,9 @@ ParsingDriver::declare_endogenous(string *name, string *tex_name, vector<pair<st
 {
   declare_symbol(name, eEndogenous, tex_name, partition_value);
   delete name;
-  if (tex_name != NULL)
+  if (tex_name != nullptr)
     delete tex_name;
-  if (partition_value != NULL)
+  if (partition_value != nullptr)
     {
       for (auto & it : *partition_value)
         {
@@ -238,7 +238,7 @@ ParsingDriver::declare_var_endogenous(string *name)
       return;
     }
 
-  declare_symbol(name, eEndogenousVAR, NULL, NULL);
+  declare_symbol(name, eEndogenousVAR, nullptr, nullptr);
   add_in_symbol_list(name);
 }
 
@@ -247,9 +247,9 @@ ParsingDriver::declare_exogenous(string *name, string *tex_name, vector<pair<str
 {
   declare_symbol(name, eExogenous, tex_name, partition_value);
   delete name;
-  if (tex_name != NULL)
+  if (tex_name != nullptr)
     delete tex_name;
-  if (partition_value != NULL)
+  if (partition_value != nullptr)
     {
       for (auto & it : *partition_value)
         {
@@ -266,9 +266,9 @@ ParsingDriver::declare_exogenous_det(string *name, string *tex_name, vector<pair
 {
   declare_symbol(name, eExogenousDet, tex_name, partition_value);
   delete name;
-  if (tex_name != NULL)
+  if (tex_name != nullptr)
     delete tex_name;
-  if (partition_value != NULL)
+  if (partition_value != nullptr)
     {
       for (auto & it : *partition_value)
         {
@@ -285,9 +285,9 @@ ParsingDriver::declare_parameter(string *name, string *tex_name, vector<pair<str
 {
   declare_symbol(name, eParameter, tex_name, partition_value);
   delete name;
-  if (tex_name != NULL)
+  if (tex_name != nullptr)
     delete tex_name;
-  if (partition_value != NULL)
+  if (partition_value != nullptr)
     {
       for (auto & it : *partition_value)
         {
@@ -305,7 +305,7 @@ ParsingDriver::declare_statement_local_variable(string *name)
   if (mod_file->symbol_table.exists(*name))
     error("Symbol " + *name + " cannot be assigned within a statement "
           +"while being assigned elsewhere in the modfile");
-  declare_symbol(name, eStatementDeclaredVariable, NULL, NULL);
+  declare_symbol(name, eStatementDeclaredVariable, nullptr, nullptr);
   delete name;
 }
 
@@ -314,7 +314,7 @@ ParsingDriver::declare_optimal_policy_discount_factor_parameter(expr_t exprnode)
 {
   string *optimalParName_declare = new string("optimal_policy_discount_factor");
   string *optimalParName_init = new string("optimal_policy_discount_factor");
-  declare_parameter(optimalParName_declare, NULL);
+  declare_parameter(optimalParName_declare, nullptr);
   init_param(optimalParName_init, exprnode);
 }
 
@@ -327,10 +327,10 @@ ParsingDriver::begin_trend()
 void
 ParsingDriver::declare_trend_var(bool log_trend, string *name, string *tex_name)
 {
-  declare_symbol(name, log_trend ? eLogTrend : eTrend, tex_name, NULL);
+  declare_symbol(name, log_trend ? eLogTrend : eTrend, tex_name, nullptr);
   declared_trend_vars.push_back(mod_file->symbol_table.getID(*name));
   delete name;
-  if (tex_name != NULL)
+  if (tex_name != nullptr)
     delete tex_name;
 }
 
@@ -481,10 +481,10 @@ ParsingDriver::add_model_variable(int symb_id, int lag)
   if (type == eModelLocalVariable && lag != 0)
     error("Model local variable " + mod_file->symbol_table.getName(symb_id) + " cannot be given a lead or a lag.");
 
-  if (dynamic_cast<StaticModel *>(model_tree) != NULL && lag != 0)
+  if (dynamic_cast<StaticModel *>(model_tree) != nullptr && lag != 0)
     error("Leads and lags on variables are forbidden in 'planner_objective'.");
 
-  if (dynamic_cast<StaticModel *>(model_tree) != NULL && type == eModelLocalVariable)
+  if (dynamic_cast<StaticModel *>(model_tree) != nullptr && type == eModelLocalVariable)
     error("Model local variable " + mod_file->symbol_table.getName(symb_id) + " cannot be used in 'planner_objective'.");
 
   // It makes sense to allow a lead/lag on parameters: during steady state calibration, endogenous and parameters can be swapped
@@ -519,12 +519,12 @@ ParsingDriver::add_expression_variable(string *name)
 void
 ParsingDriver::declare_nonstationary_var(string *name, string *tex_name, vector<pair<string *, string *> *> *partition_value)
 {
-  if (tex_name == NULL && partition_value == NULL)
+  if (tex_name == nullptr && partition_value == nullptr)
     declare_endogenous(new string(*name));
   else
-    if (tex_name == NULL)
-      declare_endogenous(new string(*name), NULL, partition_value);
-    else if (partition_value == NULL)
+    if (tex_name == nullptr)
+      declare_endogenous(new string(*name), nullptr, partition_value);
+    else if (partition_value == nullptr)
       declare_endogenous(new string(*name), tex_name);
     else
       declare_endogenous(new string(*name), tex_name, partition_value);
@@ -609,13 +609,13 @@ void
 ParsingDriver::add_VAR_restriction_coeff(string *name1, string *name2, string *lagstr)
 {
   int symb_id1 = mod_file->symbol_table.getID(*name1);
-  int symb_id2 = name2 == NULL ? -1 : mod_file->symbol_table.getID(*name2);
+  int symb_id2 = name2 == nullptr ? -1 : mod_file->symbol_table.getID(*name2);
   int lag = atoi(lagstr->c_str());
 
   var_restriction_coeff = make_pair(symb_id1, make_pair(symb_id2, lag));
 
   delete name1;
-  if (name2 != NULL)
+  if (name2 != nullptr)
     delete name2;
   delete lagstr;
 }
@@ -633,7 +633,7 @@ ParsingDriver::add_VAR_restriction_equation_or_crossequation(string *numberstr)
   double number = atof(numberstr->c_str());
   if (var_restriction_eq_or_crosseq.size() == 1)
     var_restriction_equation_or_crossequation = make_pair(make_pair(var_restriction_eq_or_crosseq[0],
-                                                                    make_pair(make_pair(-1, make_pair(-1, -1)), (expr_t) NULL)),
+                                                                    make_pair(make_pair(-1, make_pair(-1, -1)), (expr_t) nullptr)),
                                                           number);
   else
     var_restriction_equation_or_crossequation = make_pair(make_pair(var_restriction_eq_or_crosseq[0],
@@ -654,7 +654,7 @@ ParsingDriver::multiply_arg2_by_neg_one()
 void
 ParsingDriver::add_VAR_restriction_equation_or_crossequation_final(string *name)
 {
-  if (name != NULL)
+  if (name != nullptr)
     {
       int symb_id = mod_file->symbol_table.getID(*name);
       equation_restrictions[symb_id] = var_restriction_equation_or_crossequation;
@@ -2576,7 +2576,7 @@ void
 ParsingDriver::plot_conditional_forecast(string *periods)
 {
   int nperiods;
-  if (periods == NULL)
+  if (periods == nullptr)
     nperiods = -1;
   else
     {
@@ -2647,9 +2647,9 @@ ParsingDriver::add_model_equal_with_zero_rhs(expr_t arg)
 void
 ParsingDriver::declare_model_local_variable(string *name, string *tex_name)
 {
-  declare_symbol(name, eModelLocalVariable, tex_name, NULL);
+  declare_symbol(name, eModelLocalVariable, tex_name, nullptr);
   delete name;
-  if (tex_name != NULL)
+  if (tex_name != nullptr)
     delete tex_name;
 }
 
@@ -3060,7 +3060,7 @@ ParsingDriver::external_function_option(const string &name_option, const string
     {
       if (opt.empty())
         error("An argument must be passed to the 'name' option of the external_function() statement.");
-      declare_symbol(&opt, eExternalFunction, NULL, NULL);
+      declare_symbol(&opt, eExternalFunction, nullptr, nullptr);
       current_external_function_id = mod_file->symbol_table.getID(opt);
     }
   else if (name_option == "first_deriv_provided")
@@ -3069,7 +3069,7 @@ ParsingDriver::external_function_option(const string &name_option, const string