ExprNode.hh

/*
 * Copyright © 2007-2023 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 <https://www.gnu.org/licenses/>.
 */

#ifndef EXPR_NODE_HH
#define EXPR_NODE_HH

#include <functional>
#include <map>
#include <optional>
#include <ostream>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

#include "Bytecode.hh"
#include "CommonEnums.hh"
#include "ExternalFunctionsTable.hh"

class DataTree;
class NumConstNode;
class VariableNode;
class UnaryOpNode;
class BinaryOpNode;
class PacExpectationNode;

using expr_t = class ExprNode*;

struct ExprNodeLess;

//! Type for set of temporary terms
/*! The ExprNodeLess ordering is important for the temporary terms algorithm,
  see the definition of ExprNodeLess */
using temporary_terms_t = set<expr_t, ExprNodeLess>;
/*! Keeps track of array indices of temporary_terms for writing */
using temporary_terms_idxs_t = unordered_map<expr_t, int>;

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

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

//! Type for the substitution map used for creating aux. vars for diff and unary_ops
/*! Let ≅ be the equivalence relationship such that two expressions e₁ and e₂
    are equivalent iff e₁ can be obtained from e₂ by shifting all leads/lags by
    the same number of periods (e.g. x₋₁+y₂≅x₁+y₄).

    For each equivalence class, we select a representative element, which is