MathExpr.hpp

Go to the documentation of this file.

// SPDX-License-Identifier: Apache-2.0
//
// Copyright 2026 Caleb Buahin
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

 
#ifndef OPENSWMM_MATHEXPR_HPP
#define OPENSWMM_MATHEXPR_HPP
 
#include <string>
#include <vector>
#include <functional>
 
namespace openswmm {
namespace mathexpr {
 
// ============================================================================
// Token types
// ============================================================================
 
enum class TokenType : int {
    NUMBER   = 0,
    VARIABLE = 1,
    ADD      = 2,
    SUB      = 3,
    MUL      = 4,
    DIV      = 5,
    POW      = 6,
    NEG      = 7,
    LPAREN   = 8,
    RPAREN   = 9,
    FUNC_ABS  = 10,
    FUNC_SGN  = 11,
    FUNC_SQRT = 12,
    FUNC_LOG  = 13,
    FUNC_EXP  = 14,
    FUNC_SIN  = 15,
    FUNC_COS  = 16,
    FUNC_TAN  = 17,
    FUNC_ASIN = 18,
    FUNC_ACOS = 19,
    FUNC_ATAN = 20,
    FUNC_STEP = 21,
    FUNC_MIN  = 22,
    FUNC_MAX  = 23,
    COMMA     = 24,
    // Legacy mathexpr.c functions not in original refactor (Gap 49)
    FUNC_COT   = 25,  
    FUNC_SINH  = 26,  
    FUNC_COSH  = 27,  
    FUNC_TANH  = 28,  
    FUNC_COTH  = 29,  
    FUNC_LOG10 = 30,  
    FUNC_ACOT  = 31   
};
 
struct Token {
    TokenType type = TokenType::NUMBER;
    double    value = 0.0;      
    int       var_idx = -1;     
    std::string var_name;       
};
 
// ============================================================================
// Compiled expression (postfix token list)
// ============================================================================
 
struct Expression {
    std::vector<Token> postfix;  
    bool valid = false;
};
 
// ============================================================================
// Parser (Shunting-yard)
// ============================================================================

int parse(const std::string& expr_str, Expression& result);

const std::vector<std::string>& function_names();
 
// ============================================================================
// Variable binding (Tier 1 optimization)
// ============================================================================

int bind_variables(Expression& expr,
                   const char* const* name_table, int n_vars);

int compute_max_stack_depth(const Expression& expr);
 
// ============================================================================
// Evaluator
// ============================================================================

double evaluate(const Expression& expr,
                const std::function<double(const std::string&)>& var_lookup);

double evaluate(const Expression& expr, const double* vars, int n_vars);

double evaluate_fast(const Expression& expr, const double* vars) noexcept;
 
} // namespace mathexpr
} // namespace openswmm
 
#endif // OPENSWMM_MATHEXPR_HPP