/*
 * Copyright (C) 2007-2013 Dynare Team
 *
 * This file is part of Dynare.
 *
 * Dynare is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Dynare is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef _EXPR_NODE_HH
#define _EXPR_NODE_HH

using namespace std;

#include <set>
#include <map>
#include <vector>
#include <ostream>

#include "SymbolTable.hh"
#include "CodeInterpreter.hh"
#include "ExternalFunctionsTable.hh"

class DataTree;
class VariableNode;
class BinaryOpNode;

typedef class ExprNode *expr_t;

struct Model_Block;

struct ExprNodeLess;

//! Type for set of temporary terms
/*! They are ordered by index number thanks to ExprNodeLess */
typedef set<expr_t, ExprNodeLess> temporary_terms_t;

//! set of temporary terms used in a block
typedef set<int> temporary_terms_inuse_t;

typedef map<int, int> map_idx_t;

//! Type for evaluation contexts
/*! The key is a symbol id. Lags are assumed to be null */
typedef map<int, double> eval_context_t;

//! Type for tracking first/second derivative functions that have already been written as temporary terms
typedef map<pair<int, vector<expr_t> >, int> deriv_node_temp_terms_t;

//! Possible types of output when writing ExprNode(s)
enum ExprNodeOutputType
  {
    oMatlabStaticModel,                           //!< Matlab code, static model
    oMatlabDynamicModel,                          //!< Matlab code, dynamic model
    oMatlabStaticModelSparse,                     //!< Matlab code, static block decomposed model
    oMatlabDynamicModelSparse,                    //!< Matlab code, dynamic block decomposed model
    oCDynamicModel,                               //!< C code, dynamic model
    oCStaticModel,                                //!< C code, static model
    oMatlabOutsideModel,                          //!< Matlab code, outside model block (for example in initval)
    oLatexStaticModel,                            //!< LaTeX code, static model
    oLatexDynamicModel,                           //!< LaTeX code, dynamic model
    oLatexDynamicSteadyStateOperator,             //!< LaTeX code, dynamic model, inside a steady state operator
    oMatlabDynamicSteadyStateOperator,            //!< Matlab code, dynamic model, inside a steady state operator
    oMatlabDynamicSparseSteadyStateOperator,      //!< Matlab code, dynamic block decomposed model, inside a steady state operator
    oCDynamicSteadyStateOperator,                 //!< C code, dynamic model, inside a steady state operator
    oSteadyStateFile                              //!< Matlab code, in the generated steady state file
  };

#define IS_MATLAB(output_type) ((output_type) == oMatlabStaticModel     \
                                || (output_type) == oMatlabDynamicModel \
                                || (output_type) == oMatlabOutsideModel \
                                || (output_type) == oMatlabStaticModelSparse \
                                || (output_type) == oMatlabDynamicModelSparse \
                                || (output_type) == oMatlabDynamicSteadyStateOperator \
                                || (output_type) == oMatlabDynamicSparseSteadyStateOperator \
                                || (output_type) == oSteadyStateFile)

#define IS_C(output_type) ((output_type) == oCDynamicModel || (output_type) == oCStaticModel || (output_type) == oCDynamicSteadyStateOperator)

#define IS_LATEX(output_type) ((output_type) == oLatexStaticModel       \
                               || (output_type) == oLatexDynamicModel   \
                               || (output_type) == oLatexDynamicSteadyStateOperator)

/* Equal to 1 for Matlab langage, or to 0 for C language. Not defined for LaTeX.
   In Matlab, array indexes begin at 1, while they begin at 0 in C */
#define ARRAY_SUBSCRIPT_OFFSET(output_type) ((int) IS_MATLAB(output_type))

// Left and right array subscript delimiters: '(' and ')' for Matlab, '[' and ']' for C
#define LEFT_ARRAY_SUBSCRIPT(output_type) (IS_MATLAB(output_type) ? '(' : '[')
#define RIGHT_ARRAY_SUBSCRIPT(output_type) (IS_MATLAB(output_type) ? ')' : ']')

// Left and right parentheses
#define LEFT_PAR(output_type) (IS_LATEX(output_type) ? "\\left(" : "(")
#define RIGHT_PAR(output_type) (IS_LATEX(output_type) ? "\\right)" : ")")

// Computing cost above which a node can be declared a temporary term
#define MIN_COST_MATLAB (40*90)
#define MIN_COST_C (40*4)
#define MIN_COST(is_matlab) ((is_matlab) ? MIN_COST_MATLAB : MIN_COST_C)

//! Base class for expression nodes
class ExprNode
{
  friend class DataTree;
  friend class DynamicModel;
  friend class StaticModel;
  friend class ModelTree;
  friend struct ExprNodeLess;
  friend class NumConstNode;
  friend class VariableNode;
  friend class UnaryOpNode;
  friend class BinaryOpNode;
  friend class TrinaryOpNode;
  friend class ExternalFunctionNode;
private:
  //! Computes derivative w.r. to a derivation ID (but doesn't store it in derivatives map)
  /*! You shoud use getDerivative() to get the benefit of symbolic a priori and of caching */
  virtual expr_t computeDerivative(int deriv_id) = 0;

protected:
  //! Reference to the enclosing DataTree
  DataTree &datatree;

  //! Index number
  int idx;

  //! Is the data member non_null_derivatives initialized ?
  bool preparedForDerivation;

  //! Set of derivation IDs with respect to which the derivative is potentially non-null
  set<int> non_null_derivatives;

  //! Used for caching of first order derivatives (when non-null)
  map<int, expr_t> derivatives;

  //! Cost of computing current node
  /*! Nodes included in temporary_terms are considered having a null cost */
  virtual int cost(const temporary_terms_t &temporary_terms, bool is_matlab) const;

public:
  ExprNode(DataTree &datatree_arg);
  virtual ~ExprNode();

  //! Initializes data member non_null_derivatives
  virtual void prepareForDerivation() = 0;

  //! Returns derivative w.r. to derivation ID
  /*! Uses a symbolic a priori to pre-detect null derivatives, and caches the result for other derivatives (to avoid computing it several times)
    For an equal node, returns the derivative of lhs minus rhs */
  expr_t getDerivative(int deriv_id);

  //! Computes derivatives by applying the chain rule for some variables
  /*!
    \param deriv_id The derivation ID with respect to which we are derivating
    \param recursive_variables Contains the derivation ID for which chain rules must be applied. Keys are derivation IDs, values are equations of the form x=f(y) where x is the key variable and x doesn't appear in y
  */
  virtual expr_t getChainRuleDerivative(int deriv_id, const map<int, expr_t> &recursive_variables) = 0;

  //! Returns precedence of node
  /*! Equals 100 for constants, variables, unary ops, and temporary terms */
  virtual int precedence(ExprNodeOutputType output_t, const temporary_terms_t &temporary_terms) const;

  //! Fills temporary_terms set, using reference counts
  /*! A node will be marked as a temporary term if it is referenced at least two times (i.e. has at least two parents), and has a computing cost (multiplied by reference count) greater to datatree.min_cost */
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count, temporary_terms_t &temporary_terms, bool is_matlab) const;

  //! Writes output of node, using a Txxx notation for nodes in temporary_terms, and specifiying the set of already written external functions
  /*!
    \param[in] output the output stream
    \param[in] output_type the type of output (MATLAB, C, LaTeX...)
    \param[in] temporary_terms the nodes that are marked as temporary terms
    \param[in,out] tef_terms the set of already written external function nodes
  */
  virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const = 0;

  //! Writes output of node (with no temporary terms and with "outside model" output type)
  void writeOutput(ostream &output) const;

  //! Writes output of node (with no temporary terms)
  void writeOutput(ostream &output, ExprNodeOutputType output_type) const;

  //! Writes output of node, using a Txxx notation for nodes in temporary_terms
  void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms) const;

  //! Writes the output for an external function, ensuring that the external function is called as few times as possible using temporary terms
  virtual void writeExternalFunctionOutput(ostream &output, ExprNodeOutputType output_type,
                                           const temporary_terms_t &temporary_terms,
                                           deriv_node_temp_terms_t &tef_terms) const;

  virtual void compileExternalFunctionOutput(ostream &CompileCode, unsigned int &instruction_number,
                                             bool lhs_rhs, const temporary_terms_t &temporary_terms,
                                             const map_idx_t &map_idx, bool dynamic, bool steady_dynamic,
                                             deriv_node_temp_terms_t &tef_terms) const;

  //! Computes the set of all variables of a given symbol type in the expression (with information on lags)
  /*!
    Variables are stored as integer pairs of the form (symb_id, lag).
    They are added to the set given in argument.
    Note that model local variables are substituted by their expression in the computation
    (and added if type_arg = ModelLocalVariable).
  */
  virtual void collectDynamicVariables(SymbolType type_arg, set<pair<int, int> > &result) const = 0;

  //! Computes the set of all variables of a given symbol type in the expression (without information on lags)
  /*!
    Variables are stored as symb_id.
    They are added to the set given in argument.
    Note that model local variables are substituted by their expression in the computation
    (and added if type_arg = ModelLocalVariable).
  */
  void collectVariables(SymbolType type_arg, set<int> &result) const;

  //! Computes the set of endogenous variables in the expression
  /*!
    Endogenous are stored as integer pairs of the form (type_specific_id, lag).
    They are added to the set given in argument.
    Note that model local variables are substituted by their expression in the computation.
  */
  virtual void collectEndogenous(set<pair<int, int> > &result) const;

  //! Computes the set of exogenous variables in the expression
  /*!
    Exogenous are stored as integer pairs of the form (type_specific_id, lag).
    They are added to the set given in argument.
    Note that model local variables are substituted by their expression in the computation.
  */
  virtual void collectExogenous(set<pair<int, int> > &result) const;

  virtual void collectTemporary_terms(const temporary_terms_t &temporary_terms, temporary_terms_inuse_t &temporary_terms_inuse, int Curr_Block) const = 0;

  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count,
                                     temporary_terms_t &temporary_terms,
                                     map<expr_t, pair<int, int> > &first_occurence,
                                     int Curr_block,
                                     vector< vector<temporary_terms_t> > &v_temporary_terms,
                                     int equation) const;

  class EvalException

  {
  };

  class EvalExternalFunctionException : public EvalException

  {
  };

  virtual double eval(const eval_context_t &eval_context) const throw (EvalException, EvalExternalFunctionException) = 0;
  virtual void compile(ostream &CompileCode, unsigned int &instruction_number, bool lhs_rhs, const temporary_terms_t &temporary_terms, const map_idx_t &map_idx, bool dynamic, bool steady_dynamic, deriv_node_temp_terms_t &tef_terms) const = 0;
  void compile(ostream &CompileCode, unsigned int &instruction_number, bool lhs_rhs, const temporary_terms_t &temporary_terms, const map_idx_t &map_idx, bool dynamic, bool steady_dynamic) const;
  //! Creates a static version of this node
  /*!
    This method duplicates the current node by creating a similar node from which all leads/lags have been stripped,
    adds the result in the static_datatree argument (and not in the original datatree), and returns it.
  */
  virtual expr_t toStatic(DataTree &static_datatree) const = 0;
  //! Try to normalize an equation linear in its endogenous variable
  virtual pair<int, expr_t> normalizeEquation(int symb_id_endo, vector<pair<int, pair<expr_t, expr_t> > > &List_of_Op_RHS) const = 0;

  //! Returns the maximum lead of endogenous in this expression
  /*! Always returns a non-negative value */
  virtual int maxEndoLead() const = 0;

  //! Returns the maximum lead of exogenous in this expression
  /*! Always returns a non-negative value */
  virtual int maxExoLead() const = 0;

  //! Returns the maximum lag of endogenous in this expression
  /*! Always returns a non-negative value */
  virtual int maxEndoLag() const = 0;

  //! Returns the maximum lag of exogenous in this expression
  /*! Always returns a non-negative value */
  virtual int maxExoLag() const = 0;

  //! Returns the relative period of the most forward term in this expression
  /*! A negative value means that the expression contains only lagged variables */
  virtual int maxLead() const = 0;

  //! Returns a new expression where all the leads/lags have been shifted backwards by the same amount
  /*!
    Only acts on endogenous, exogenous, exogenous det
    \param[in] n The number of lags by which to shift
    \return The same expression except that leads/lags have been shifted backwards
  */
  virtual expr_t decreaseLeadsLags(int n) const = 0;

  //! Type for the substitution map used in the process of creating auxiliary vars for leads >= 2
  typedef map<const ExprNode *, const VariableNode *> subst_table_t;

  //! Creates auxiliary endo lead variables corresponding to this expression
  /*!
    If maximum endogenous lead >= 3, this method will also create intermediary auxiliary var, and will add the equations of the form aux1 = aux2(+1) to the substitution table.
    \pre This expression is assumed to have maximum endogenous lead >= 2
    \param[in,out] subst_table The table to which new auxiliary variables and their correspondance will be added
    \param[out] neweqs Equations to be added to the model to match the creation of auxiliary variables.
    \return The new variable node corresponding to the current expression
  */
  VariableNode *createEndoLeadAuxiliaryVarForMyself(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;

  //! Creates auxiliary exo lead variables corresponding to this expression
  /*!
    If maximum exogenous lead >= 2, this method will also create intermediary auxiliary var, and will add the equations of the form aux1 = aux2(+1) to the substitution table.
    \pre This expression is assumed to have maximum exogenous lead >= 1
    \param[in,out] subst_table The table to which new auxiliary variables and their correspondance will be added
    \param[out] neweqs Equations to be added to the model to match the creation of auxiliary variables.
    \return The new variable node corresponding to the current expression
  */
  VariableNode *createExoLeadAuxiliaryVarForMyself(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;

  //! Constructs a new expression where sub-expressions with max endo lead >= 2 have been replaced by auxiliary variables
  /*!
    \param[in,out] subst_table Map used to store expressions that have already be substituted and their corresponding variable, in order to avoid creating two auxiliary variables for the same sub-expr.
    \param[out] neweqs Equations to be added to the model to match the creation of auxiliary variables.

    If the method detects a sub-expr which needs to be substituted, two cases are possible:
    - if this expr is in the table, then it will use the corresponding variable and return the substituted expression
    - if this expr is not in the table, then it will create an auxiliary endogenous variable, add the substitution in the table and return the substituted expression

    \return A new equivalent expression where sub-expressions with max endo lead >= 2 have been replaced by auxiliary variables
  */
  virtual expr_t substituteEndoLeadGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const = 0;

  //! Constructs a new expression where endo variables with max endo lag >= 2 have been replaced by auxiliary variables
  /*!
    \param[in,out] subst_table Map used to store expressions that have already be substituted and their corresponding variable, in order to avoid creating two auxiliary variables for the same sub-expr.
    \param[out] neweqs Equations to be added to the model to match the creation of auxiliary variables.
  */
  virtual expr_t substituteEndoLagGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const = 0;

  //! Constructs a new expression where exogenous variables with a lead have been replaced by auxiliary variables
  /*!
    \param[in,out] subst_table Map used to store expressions that have already be substituted and their corresponding variable, in order to avoid creating two auxiliary variables for the same sub-expr.
    \param[out] neweqs Equations to be added to the model to match the creation of auxiliary variables.
  */
  virtual expr_t substituteExoLead(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const = 0;
  //! Constructs a new expression where exogenous variables with a lag have been replaced by auxiliary variables
  /*!
    \param[in,out] subst_table Map used to store expressions that have already be substituted and their corresponding variable, in order to avoid creating two auxiliary variables for the same sub-expr.
    \param[out] neweqs Equations to be added to the model to match the creation of auxiliary variables.
  */
  virtual expr_t substituteExoLag(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const = 0;

  //! Constructs a new expression where the expectation operator has been replaced by auxiliary variables
  /*!
    \param[in,out] subst_table Map used to store expressions that have already be substituted and their corresponding variable, in order to avoid creating two auxiliary variables for the same sub-expr.
    \param[out] neweqs Equations to be added to the model to match the creation of auxiliary variables.
    \param[in] partial_information_model Are we substituting in a partial information model?
  */
  virtual expr_t substituteExpectation(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool partial_information_model) const = 0;

  virtual expr_t decreaseLeadsLagsPredeterminedVariables() const = 0;

  //! Constructs a new expression where forward variables (supposed to be at most in t+1) have been replaced by themselves at t, plus a new aux var representing their (time) differentiate
  /*!
    \param[in] subset variables to which to limit the transformation; transform
    all fwrd vars if empty
    \param[in,out] subst_table Map used to store mapping between a given
    forward variable and the aux var that contains its differentiate
    \param[out] neweqs Equations to be added to the model to match the creation of auxiliary variables.
  */
  virtual expr_t differentiateForwardVars(const vector<string> &subset, subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const = 0;

  //! Return true if the nodeID is a numerical constant equal to value and false otherwise
  /*!
    \param[in] value of the numerical constante
    \param[out] the boolean equal to true if NodeId is a constant equal to value
  */
  virtual bool isNumConstNodeEqualTo(double value) const = 0;

  //! Returns true if the expression contains one or several endogenous variable
  virtual bool containsEndogenous(void) const = 0;

  //! Return true if the nodeID is a variable withe a type equal to type_arg, a specific variable id aqual to varfiable_id and a lag equal to lag_arg and false otherwise
  /*!
    \param[in] the type (type_arg), specifique variable id (variable_id and the lag (lag_arg)
    \param[out] the boolean equal to true if NodeId is the variable
  */
  virtual bool isVariableNodeEqualTo(SymbolType type_arg, int variable_id, int lag_arg) const = 0;

  //! Replaces the Trend var with datatree.One
  virtual expr_t replaceTrendVar() const = 0;

  //! Constructs a new expression where the variable indicated by symb_id has been detrended
  /*!
    \param[in] symb_id indicating the variable to be detrended
    \param[in] log_trend indicates if the trend is in log
    \param[in] trend indicating the trend
    \return the new binary op pointing to a detrended variable
  */
  virtual expr_t detrend(int symb_id, bool log_trend, expr_t trend) const = 0;

  //! Add ExprNodes to the provided datatree
  virtual expr_t cloneDynamic(DataTree &dynamic_datatree) const = 0;

  //! Move a trend variable with lag/lead to time t by dividing/multiplying by its growth factor
  virtual expr_t removeTrendLeadLag(map<int, expr_t> trend_symbols_map) const = 0;

  //! Returns true if the expression is in static form (no lead, no lag, no expectation, no STEADY_STATE)
  virtual bool isInStaticForm() const = 0;
};

//! Object used to compare two nodes (using their indexes)
struct ExprNodeLess
{
  bool
  operator()(expr_t arg1, expr_t arg2) const
  {
    return arg1->idx < arg2->idx;
  }
};

//! Numerical constant node
/*! The constant is necessarily non-negative (this is enforced at the NumericalConstants class level) */
class NumConstNode : public ExprNode
{
private:
  //! Id from numerical constants table
  const int id;
  virtual expr_t computeDerivative(int deriv_id);
public:
  NumConstNode(DataTree &datatree_arg, int id_arg);
  int
  get_id() const
  {
    return id;
  };
  virtual void prepareForDerivation();
  virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
  virtual void collectDynamicVariables(SymbolType type_arg, set<pair<int, int> > &result) const;
  virtual void collectTemporary_terms(const temporary_terms_t &temporary_terms, temporary_terms_inuse_t &temporary_terms_inuse, int Curr_Block) const;
  virtual double eval(const eval_context_t &eval_context) const throw (EvalException, EvalExternalFunctionException);
  virtual void compile(ostream &CompileCode, unsigned int &instruction_number, bool lhs_rhs, const temporary_terms_t &temporary_terms, const map_idx_t &map_idx, bool dynamic, bool steady_dynamic, deriv_node_temp_terms_t &tef_terms) const;
  virtual expr_t toStatic(DataTree &static_datatree) const;
  virtual pair<int, expr_t> normalizeEquation(int symb_id_endo, vector<pair<int, pair<expr_t, expr_t> > >  &List_of_Op_RHS) const;
  virtual expr_t getChainRuleDerivative(int deriv_id, const map<int, expr_t> &recursive_variables);
  virtual int maxEndoLead() const;
  virtual int maxExoLead() const;
  virtual int maxEndoLag() const;
  virtual int maxExoLag() const;
  virtual int maxLead() const;
  virtual expr_t decreaseLeadsLags(int n) const;
  virtual expr_t substituteEndoLeadGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  virtual expr_t substituteEndoLagGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExoLead(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  virtual expr_t substituteExoLag(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExpectation(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool partial_information_model) const;
  virtual expr_t decreaseLeadsLagsPredeterminedVariables() const;
  virtual expr_t differentiateForwardVars(const vector<string> &subset, subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual bool isNumConstNodeEqualTo(double value) const;
  virtual bool containsEndogenous(void) const;
  virtual bool isVariableNodeEqualTo(SymbolType type_arg, int variable_id, int lag_arg) const;
  virtual expr_t replaceTrendVar() const;
  virtual expr_t detrend(int symb_id, bool log_trend, expr_t trend) const;
  virtual expr_t cloneDynamic(DataTree &dynamic_datatree) const;
  virtual expr_t removeTrendLeadLag(map<int, expr_t> trend_symbols_map) const;
  virtual bool isInStaticForm() const;
};

//! Symbol or variable node
class VariableNode : public ExprNode
{
  friend class UnaryOpNode;
private:
  //! Id from the symbol table
  const int symb_id;
  const SymbolType type;
  //! A positive value is a lead, a negative is a lag
  const int lag;
  virtual expr_t computeDerivative(int deriv_id);
public:
  VariableNode(DataTree &datatree_arg, int symb_id_arg, int lag_arg);
  virtual void prepareForDerivation();
  virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
  virtual void collectDynamicVariables(SymbolType type_arg, set<pair<int, int> > &result) const;
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count,
                                     temporary_terms_t &temporary_terms,
                                     map<expr_t, pair<int, int> > &first_occurence,
                                     int Curr_block,
                                     vector< vector<temporary_terms_t> > &v_temporary_terms,
                                     int equation) const;
  virtual void collectTemporary_terms(const temporary_terms_t &temporary_terms, temporary_terms_inuse_t &temporary_terms_inuse, int Curr_Block) const;
  virtual double eval(const eval_context_t &eval_context) const throw (EvalException, EvalExternalFunctionException);
  virtual void compile(ostream &CompileCode, unsigned int &instruction_number, bool lhs_rhs, const temporary_terms_t &temporary_terms, const map_idx_t &map_idx, bool dynamic, bool steady_dynamic, deriv_node_temp_terms_t &tef_terms) const;
  virtual expr_t toStatic(DataTree &static_datatree) const;
  SymbolType
  get_type() const
  {
    return type;
  };
  int
  get_symb_id() const
  {
    return symb_id;
  };
  int get_lag() const { return lag; };
  virtual pair<int, expr_t> normalizeEquation(int symb_id_endo, vector<pair<int, pair<expr_t, expr_t> > >  &List_of_Op_RHS) const;
  virtual expr_t getChainRuleDerivative(int deriv_id, const map<int, expr_t> &recursive_variables);
  virtual int maxEndoLead() const;
  virtual int maxExoLead() const;
  virtual int maxEndoLag() const;
  virtual int maxExoLag() const;
  virtual int maxLead() const;
  virtual expr_t decreaseLeadsLags(int n) const;
  virtual expr_t substituteEndoLeadGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  virtual expr_t substituteEndoLagGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExoLead(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  virtual expr_t substituteExoLag(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExpectation(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool partial_information_model) const;
  virtual expr_t decreaseLeadsLagsPredeterminedVariables() const;
  virtual expr_t differentiateForwardVars(const vector<string> &subset, subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual bool isNumConstNodeEqualTo(double value) const;
  virtual bool containsEndogenous(void) const;
  virtual bool isVariableNodeEqualTo(SymbolType type_arg, int variable_id, int lag_arg) const;
  virtual expr_t replaceTrendVar() const;
  virtual expr_t detrend(int symb_id, bool log_trend, expr_t trend) const;
  virtual expr_t cloneDynamic(DataTree &dynamic_datatree) const;
  virtual expr_t removeTrendLeadLag(map<int, expr_t> trend_symbols_map) const;
  virtual bool isInStaticForm() const;
};

//! Unary operator node
class UnaryOpNode : public ExprNode
{
private:
  const expr_t arg;
  //! Stores the information set. Only used for expectation operator
  const int expectation_information_set;
  //! Only used for oSteadyStateParamDeriv and oSteadyStateParam2ndDeriv
  const int param1_symb_id, param2_symb_id;
  const UnaryOpcode op_code;
  virtual expr_t computeDerivative(int deriv_id);
  virtual int cost(const temporary_terms_t &temporary_terms, bool is_matlab) const;
  //! Returns the derivative of this node if darg is the derivative of the argument
  expr_t composeDerivatives(expr_t darg, int deriv_id);
public:
  UnaryOpNode(DataTree &datatree_arg, UnaryOpcode op_code_arg, const expr_t arg_arg, int expectation_information_set_arg, int param1_symb_id_arg, int param2_symb_id_arg);
  virtual void prepareForDerivation();
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count, temporary_terms_t &temporary_terms, bool is_matlab) const;
  virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
  virtual void writeExternalFunctionOutput(ostream &output, ExprNodeOutputType output_type,
                                           const temporary_terms_t &temporary_terms,
                                           deriv_node_temp_terms_t &tef_terms) const;
  virtual void compileExternalFunctionOutput(ostream &CompileCode, unsigned int &instruction_number,
                                             bool lhs_rhs, const temporary_terms_t &temporary_terms,
                                             const map_idx_t &map_idx, bool dynamic, bool steady_dynamic,
                                             deriv_node_temp_terms_t &tef_terms) const;
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count,
                                     temporary_terms_t &temporary_terms,
                                     map<expr_t, pair<int, int> > &first_occurence,
                                     int Curr_block,
                                     vector< vector<temporary_terms_t> > &v_temporary_terms,
                                     int equation) const;
  virtual void collectDynamicVariables(SymbolType type_arg, set<pair<int, int> > &result) const;
  virtual void collectTemporary_terms(const temporary_terms_t &temporary_terms, temporary_terms_inuse_t &temporary_terms_inuse, int Curr_Block) const;
  static double eval_opcode(UnaryOpcode op_code, double v) throw (EvalException, EvalExternalFunctionException);
  virtual double eval(const eval_context_t &eval_context) const throw (EvalException, EvalExternalFunctionException);
  virtual void compile(ostream &CompileCode, unsigned int &instruction_number, bool lhs_rhs, const temporary_terms_t &temporary_terms, const map_idx_t &map_idx, bool dynamic, bool steady_dynamic, deriv_node_temp_terms_t &tef_terms) const;
  //! Returns operand
  expr_t
  get_arg() const
  {
    return (arg);
  };
  //! Returns op code
  UnaryOpcode
  get_op_code() const
  {
    return (op_code);
  };
  virtual expr_t toStatic(DataTree &static_datatree) const;
  virtual pair<int, expr_t> normalizeEquation(int symb_id_endo, vector<pair<int, pair<expr_t, expr_t> > >  &List_of_Op_RHS) const;
  virtual expr_t getChainRuleDerivative(int deriv_id, const map<int, expr_t> &recursive_variables);
  virtual int maxEndoLead() const;
  virtual int maxExoLead() const;
  virtual int maxEndoLag() const;
  virtual int maxExoLag() const;
  virtual int maxLead() const;
  virtual expr_t decreaseLeadsLags(int n) const;
  virtual expr_t substituteEndoLeadGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  //! Creates another UnaryOpNode with the same opcode, but with a possibly different datatree and argument
  expr_t buildSimilarUnaryOpNode(expr_t alt_arg, DataTree &alt_datatree) const;
  virtual expr_t substituteEndoLagGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExoLead(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  virtual expr_t substituteExoLag(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExpectation(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool partial_information_model) const;
  virtual expr_t decreaseLeadsLagsPredeterminedVariables() const;
  virtual expr_t differentiateForwardVars(const vector<string> &subset, subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual bool isNumConstNodeEqualTo(double value) const;
  virtual bool containsEndogenous(void) const;
  virtual bool isVariableNodeEqualTo(SymbolType type_arg, int variable_id, int lag_arg) const;
  virtual expr_t replaceTrendVar() const;
  virtual expr_t detrend(int symb_id, bool log_trend, expr_t trend) const;
  virtual expr_t cloneDynamic(DataTree &dynamic_datatree) const;
  virtual expr_t removeTrendLeadLag(map<int, expr_t> trend_symbols_map) const;
  virtual bool isInStaticForm() const;
};

//! Binary operator node
class BinaryOpNode : public ExprNode
{
private:
  const expr_t arg1, arg2;
  const BinaryOpcode op_code;
  virtual expr_t computeDerivative(int deriv_id);
  virtual int cost(const temporary_terms_t &temporary_terms, bool is_matlab) const;
  //! Returns the derivative of this node if darg1 and darg2 are the derivatives of the arguments
  expr_t composeDerivatives(expr_t darg1, expr_t darg2);
  const int powerDerivOrder;
public:
  BinaryOpNode(DataTree &datatree_arg, const expr_t arg1_arg,
               BinaryOpcode op_code_arg, const expr_t arg2_arg);
  BinaryOpNode(DataTree &datatree_arg, const expr_t arg1_arg,
               BinaryOpcode op_code_arg, const expr_t arg2_arg, int powerDerivOrder);
  virtual void prepareForDerivation();
  virtual int precedence(ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms) const;
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count, temporary_terms_t &temporary_terms, bool is_matlab) const;
  virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
  virtual void writeExternalFunctionOutput(ostream &output, ExprNodeOutputType output_type,
                                           const temporary_terms_t &temporary_terms,
                                           deriv_node_temp_terms_t &tef_terms) const;
  virtual void compileExternalFunctionOutput(ostream &CompileCode, unsigned int &instruction_number,
                                             bool lhs_rhs, const temporary_terms_t &temporary_terms,
                                             const map_idx_t &map_idx, bool dynamic, bool steady_dynamic,
                                             deriv_node_temp_terms_t &tef_terms) const;
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count,
                                     temporary_terms_t &temporary_terms,
                                     map<expr_t, pair<int, int> > &first_occurence,
                                     int Curr_block,
                                     vector< vector<temporary_terms_t> > &v_temporary_terms,
                                     int equation) const;
  virtual void collectDynamicVariables(SymbolType type_arg, set<pair<int, int> > &result) const;
  virtual void collectTemporary_terms(const temporary_terms_t &temporary_terms, temporary_terms_inuse_t &temporary_terms_inuse, int Curr_Block) const;
  static double eval_opcode(double v1, BinaryOpcode op_code, double v2, int derivOrder) throw (EvalException, EvalExternalFunctionException);
  virtual double eval(const eval_context_t &eval_context) const throw (EvalException, EvalExternalFunctionException);
  virtual void compile(ostream &CompileCode, unsigned int &instruction_number, bool lhs_rhs, const temporary_terms_t &temporary_terms, const map_idx_t &map_idx, bool dynamic, bool steady_dynamic, deriv_node_temp_terms_t &tef_terms) const;
  virtual expr_t Compute_RHS(expr_t arg1, expr_t arg2, int op, int op_type) const;
  //! Returns first operand
  expr_t
  get_arg1() const
  {
    return (arg1);
  };
  //! Returns second operand
  expr_t
  get_arg2() const
  {
    return (arg2);
  };
  //! Returns op code
  BinaryOpcode
  get_op_code() const
  {
    return (op_code);
  };
  int
  get_power_deriv_order() const
  {
    return powerDerivOrder;
  }
  virtual expr_t toStatic(DataTree &static_datatree) const;
  virtual pair<int, expr_t> normalizeEquation(int symb_id_endo, vector<pair<int, pair<expr_t, expr_t> > >  &List_of_Op_RHS) const;
  virtual expr_t getChainRuleDerivative(int deriv_id, const map<int, expr_t> &recursive_variables);
  virtual int maxEndoLead() const;
  virtual int maxExoLead() const;
  virtual int maxEndoLag() const;
  virtual int maxExoLag() const;
  virtual int maxLead() const;
  virtual expr_t decreaseLeadsLags(int n) const;
  virtual expr_t substituteEndoLeadGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  //! Creates another BinaryOpNode with the same opcode, but with a possibly different datatree and arguments
  expr_t buildSimilarBinaryOpNode(expr_t alt_arg1, expr_t alt_arg2, DataTree &alt_datatree) const;
  virtual expr_t substituteEndoLagGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExoLead(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  virtual expr_t substituteExoLag(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExpectation(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool partial_information_model) const;
  virtual expr_t decreaseLeadsLagsPredeterminedVariables() const;
  virtual expr_t differentiateForwardVars(const vector<string> &subset, subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual bool isNumConstNodeEqualTo(double value) const;
  virtual bool containsEndogenous(void) const;
  virtual bool isVariableNodeEqualTo(SymbolType type_arg, int variable_id, int lag_arg) const;
  virtual expr_t replaceTrendVar() const;
  virtual expr_t detrend(int symb_id, bool log_trend, expr_t trend) const;
  virtual expr_t cloneDynamic(DataTree &dynamic_datatree) const;
  virtual expr_t removeTrendLeadLag(map<int, expr_t> trend_symbols_map) const;
  //! Function to write out the oPowerNode in expr_t terms as opposed to writing out the function itself
  expr_t unpackPowerDeriv() const;
  //! Returns MULT_i*(lhs-rhs) = 0, creating multiplier MULT_i
  expr_t addMultipliersToConstraints(int i);
  //! Returns the non-zero hand-side of an equation (that must have a hand side equal to zero)
  expr_t getNonZeroPartofEquation() const;
  virtual bool isInStaticForm() const;
};

//! Trinary operator node
class TrinaryOpNode : public ExprNode
{
  friend class ModelTree;
private:
  const expr_t arg1, arg2, arg3;
  const TrinaryOpcode op_code;
  virtual expr_t computeDerivative(int deriv_id);
  virtual int cost(const temporary_terms_t &temporary_terms, bool is_matlab) const;
  //! Returns the derivative of this node if darg1, darg2 and darg3 are the derivatives of the arguments
  expr_t composeDerivatives(expr_t darg1, expr_t darg2, expr_t darg3);
public:
  TrinaryOpNode(DataTree &datatree_arg, const expr_t arg1_arg,
                TrinaryOpcode op_code_arg, const expr_t arg2_arg, const expr_t arg3_arg);
  virtual void prepareForDerivation();
  virtual int precedence(ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms) const;
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count, temporary_terms_t &temporary_terms, bool is_matlab) const;
  virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
  virtual void writeExternalFunctionOutput(ostream &output, ExprNodeOutputType output_type,
                                           const temporary_terms_t &temporary_terms,
                                           deriv_node_temp_terms_t &tef_terms) const;
  virtual void compileExternalFunctionOutput(ostream &CompileCode, unsigned int &instruction_number,
                                             bool lhs_rhs, const temporary_terms_t &temporary_terms,
                                             const map_idx_t &map_idx, bool dynamic, bool steady_dynamic,
                                             deriv_node_temp_terms_t &tef_terms) const;
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count,
                                     temporary_terms_t &temporary_terms,
                                     map<expr_t, pair<int, int> > &first_occurence,
                                     int Curr_block,
                                     vector< vector<temporary_terms_t> > &v_temporary_terms,
                                     int equation) const;
  virtual void collectDynamicVariables(SymbolType type_arg, set<pair<int, int> > &result) const;
  virtual void collectTemporary_terms(const temporary_terms_t &temporary_terms, temporary_terms_inuse_t &temporary_terms_inuse, int Curr_Block) const;
  static double eval_opcode(double v1, TrinaryOpcode op_code, double v2, double v3) throw (EvalException, EvalExternalFunctionException);
  virtual double eval(const eval_context_t &eval_context) const throw (EvalException, EvalExternalFunctionException);
  virtual void compile(ostream &CompileCode, unsigned int &instruction_number, bool lhs_rhs, const temporary_terms_t &temporary_terms, const map_idx_t &map_idx, bool dynamic, bool steady_dynamic, deriv_node_temp_terms_t &tef_terms) const;
  virtual expr_t toStatic(DataTree &static_datatree) const;
  virtual pair<int, expr_t> normalizeEquation(int symb_id_endo, vector<pair<int, pair<expr_t, expr_t> > >  &List_of_Op_RHS) const;
  virtual expr_t getChainRuleDerivative(int deriv_id, const map<int, expr_t> &recursive_variables);
  virtual int maxEndoLead() const;
  virtual int maxExoLead() const;
  virtual int maxEndoLag() const;
  virtual int maxExoLag() const;
  virtual int maxLead() const;
  virtual expr_t decreaseLeadsLags(int n) const;
  virtual expr_t substituteEndoLeadGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  //! Creates another TrinaryOpNode with the same opcode, but with a possibly different datatree and arguments
  expr_t buildSimilarTrinaryOpNode(expr_t alt_arg1, expr_t alt_arg2, expr_t alt_arg3, DataTree &alt_datatree) const;
  virtual expr_t substituteEndoLagGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExoLead(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  virtual expr_t substituteExoLag(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExpectation(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool partial_information_model) const;
  virtual expr_t decreaseLeadsLagsPredeterminedVariables() const;
  virtual expr_t differentiateForwardVars(const vector<string> &subset, subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual bool isNumConstNodeEqualTo(double value) const;
  virtual bool containsEndogenous(void) const;
  virtual bool isVariableNodeEqualTo(SymbolType type_arg, int variable_id, int lag_arg) const;
  virtual expr_t replaceTrendVar() const;
  virtual expr_t detrend(int symb_id, bool log_trend, expr_t trend) const;
  virtual expr_t cloneDynamic(DataTree &dynamic_datatree) const;
  virtual expr_t removeTrendLeadLag(map<int, expr_t> trend_symbols_map) const;
  virtual bool isInStaticForm() const;
};

//! External function node
class ExternalFunctionNode : public ExprNode
{
private:
  virtual expr_t computeDerivative(int deriv_id);
  virtual expr_t composeDerivatives(const vector<expr_t> &dargs);
protected:
  //! Thrown when trying to access an unknown entry in external_function_node_map
  class UnknownFunctionNameAndArgs
  {
  };
  const int symb_id;
  const vector<expr_t> arguments;
  //! Returns true if the given external function has been written as a temporary term
  bool alreadyWrittenAsTefTerm(int the_symb_id, deriv_node_temp_terms_t &tef_terms) const;
  //! Returns the index in the tef_terms map of this external function
  int getIndxInTefTerms(int the_symb_id, deriv_node_temp_terms_t &tef_terms) const throw (UnknownFunctionNameAndArgs);
  //! Helper function to write output arguments of any given external function
  void writeExternalFunctionArguments(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
public:
  ExternalFunctionNode(DataTree &datatree_arg, int symb_id_arg,
                       const vector<expr_t> &arguments_arg);
  virtual void prepareForDerivation();
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count, temporary_terms_t &temporary_terms, bool is_matlab) const;
  virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
  virtual void writeExternalFunctionOutput(ostream &output, ExprNodeOutputType output_type,
                                           const temporary_terms_t &temporary_terms,
                                           deriv_node_temp_terms_t &tef_terms) const;
  virtual void compileExternalFunctionOutput(ostream &CompileCode, unsigned int &instruction_number,
                                             bool lhs_rhs, const temporary_terms_t &temporary_terms,
                                             const map_idx_t &map_idx, bool dynamic, bool steady_dynamic,
                                             deriv_node_temp_terms_t &tef_terms) const;
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count,
                                     temporary_terms_t &temporary_terms,
                                     map<expr_t, pair<int, int> > &first_occurence,
                                     int Curr_block,
                                     vector< vector<temporary_terms_t> > &v_temporary_terms,
                                     int equation) const;
  virtual void collectDynamicVariables(SymbolType type_arg, set<pair<int, int> > &result) const;
  virtual void collectTemporary_terms(const temporary_terms_t &temporary_terms, temporary_terms_inuse_t &temporary_terms_inuse, int Curr_Block) const;
  virtual double eval(const eval_context_t &eval_context) const throw (EvalException, EvalExternalFunctionException);
  unsigned int compileExternalFunctionArguments(ostream &CompileCode, unsigned int &instruction_number,
                                                bool lhs_rhs, const temporary_terms_t &temporary_terms,
                                                const map_idx_t &map_idx, bool dynamic, bool steady_dynamic,
                                                deriv_node_temp_terms_t &tef_terms) const;

  virtual void compile(ostream &CompileCode, unsigned int &instruction_number, bool lhs_rhs, const temporary_terms_t &temporary_terms, const map_idx_t &map_idx, bool dynamic, bool steady_dynamic, deriv_node_temp_terms_t &tef_terms) const;
  virtual expr_t toStatic(DataTree &static_datatree) const;
  virtual pair<int, expr_t> normalizeEquation(int symb_id_endo, vector<pair<int, pair<expr_t, expr_t> > >  &List_of_Op_RHS) const;
  virtual expr_t getChainRuleDerivative(int deriv_id, const map<int, expr_t> &recursive_variables);
  virtual int maxEndoLead() const;
  virtual int maxExoLead() const;
  virtual int maxEndoLag() const;
  virtual int maxExoLag() const;
  virtual int maxLead() const;
  virtual expr_t decreaseLeadsLags(int n) const;
  virtual expr_t substituteEndoLeadGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  virtual expr_t substituteEndoLagGreaterThanTwo(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExoLead(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool deterministic_model) const;
  virtual expr_t substituteExoLag(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual expr_t substituteExpectation(subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs, bool partial_information_model) const;
  virtual expr_t buildSimilarExternalFunctionNode(vector<expr_t> &alt_args, DataTree &alt_datatree) const;
  virtual expr_t decreaseLeadsLagsPredeterminedVariables() const;
  virtual expr_t differentiateForwardVars(const vector<string> &subset, subst_table_t &subst_table, vector<BinaryOpNode *> &neweqs) const;
  virtual bool isNumConstNodeEqualTo(double value) const;
  virtual bool containsEndogenous(void) const;
  virtual bool isVariableNodeEqualTo(SymbolType type_arg, int variable_id, int lag_arg) const;
  virtual void writePrhs(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms, const string &ending) const;
  virtual expr_t replaceTrendVar() const;
  virtual expr_t detrend(int symb_id, bool log_trend, expr_t trend) const;
  virtual expr_t cloneDynamic(DataTree &dynamic_datatree) const;
  virtual expr_t removeTrendLeadLag(map<int, expr_t> trend_symbols_map) const;
  virtual bool isInStaticForm() const;
};

class FirstDerivExternalFunctionNode : public ExternalFunctionNode
{
private:
  const int inputIndex;
  virtual expr_t composeDerivatives(const vector<expr_t> &dargs);
public:
  FirstDerivExternalFunctionNode(DataTree &datatree_arg,
                                 int top_level_symb_id_arg,
                                 const vector<expr_t> &arguments_arg,
                                 int inputIndex_arg);
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count, temporary_terms_t &temporary_terms, bool is_matlab) const;
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count,
                                     temporary_terms_t &temporary_terms,
                                     map<expr_t, pair<int, int> > &first_occurence,
                                     int Curr_block,
                                     vector< vector<temporary_terms_t> > &v_temporary_terms,
                                     int equation) const;
  virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
  virtual void compile(ostream &CompileCode, unsigned int &instruction_number,
                       bool lhs_rhs, const temporary_terms_t &temporary_terms,
                       const map_idx_t &map_idx, bool dynamic, bool steady_dynamic,
                       deriv_node_temp_terms_t &tef_terms) const;
  virtual void writeExternalFunctionOutput(ostream &output, ExprNodeOutputType output_type,
                                           const temporary_terms_t &temporary_terms,
                                           deriv_node_temp_terms_t &tef_terms) const;
  virtual void compileExternalFunctionOutput(ostream &CompileCode, unsigned int &instruction_number,
                                             bool lhs_rhs, const temporary_terms_t &temporary_terms,
                                             const map_idx_t &map_idx, bool dynamic, bool steady_dynamic,
                                             deriv_node_temp_terms_t &tef_terms) const;
};

class SecondDerivExternalFunctionNode : public ExternalFunctionNode
{
private:
  const int inputIndex1;
  const int inputIndex2;
  virtual expr_t computeDerivative(int deriv_id);
public:
  SecondDerivExternalFunctionNode(DataTree &datatree_arg,
                                  int top_level_symb_id_arg,
                                  const vector<expr_t> &arguments_arg,
                                  int inputIndex1_arg,
                                  int inputIndex2_arg);
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count, temporary_terms_t &temporary_terms, bool is_matlab) const;
  virtual void computeTemporaryTerms(map<expr_t, int> &reference_count,
                                     temporary_terms_t &temporary_terms,
                                     map<expr_t, pair<int, int> > &first_occurence,
                                     int Curr_block,
                                     vector< vector<temporary_terms_t> > &v_temporary_terms,
                                     int equation) const;
  virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
  virtual void writeExternalFunctionOutput(ostream &output, ExprNodeOutputType output_type,
                                           const temporary_terms_t &temporary_terms,
                                           deriv_node_temp_terms_t &tef_terms) const;
};

#endif
