expression.hpp

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#pragma once
 
// Expression — simple math expression evaluator.
// Supports: +, -, *, /, ^, (), variables, and common functions (sin, cos, sqrt, abs, min, max).
// No external dependencies (no exprtk).
 
#include <string>
#include <string_view>
#include <map>
#include <optional>
#include <functional>
 
namespace pulp::runtime {

std::optional<double> evaluate(std::string_view expression,
                                const std::map<std::string, double>& variables = {});

class ExpressionEvaluator {
public:
    ExpressionEvaluator() = default;

    void set(std::string_view name, double value);

    std::optional<double> get(std::string_view name) const;

    std::optional<double> evaluate(std::string_view expression) const;

    void register_function(std::string_view name, std::function<double(double)> fn);

    void clear_variables();
 
private:
    std::map<std::string, double, std::less<>> variables_;
    std::map<std::string, std::function<double(double)>, std::less<>> custom_functions_;
};
 
}  // namespace pulp::runtime