41 lines
1.2 KiB
C++
41 lines
1.2 KiB
C++
#pragma once
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#include <memory>
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#include <string>
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// Forward declaration so tinyexpr.h stays out of this header.
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struct te_expr;
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// Compiled single-variable expression. The bound variable is named x.
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// Compile once at config load; evaluate many times at simulation time.
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// tinyexpr bakes the address of the bound variable into the compiled tree, so
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// we keep x on the heap to preserve that pointer across moves.
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class Formula
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{
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public:
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Formula() = default;
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Formula(const Formula&) = delete;
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Formula& operator=(const Formula&) = delete;
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Formula(Formula&& other) noexcept;
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Formula& operator=(Formula&& other) noexcept;
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~Formula();
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// Parses source and returns a ready-to-evaluate Formula.
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// Throws std::runtime_error with the source and error position on failure.
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static Formula compile(const std::string& source);
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// Evaluates the expression at the given x. Requires a compiled formula.
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double evaluate(double x) const;
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const std::string& source() const { return m_source; }
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bool isValid() const { return m_expr != nullptr; }
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private:
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std::string m_source;
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std::unique_ptr<double> m_x;
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te_expr* m_expr = nullptr;
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};
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