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#ifndef MBGL_STYLE_FUNCTION_PROPERTIES
#define MBGL_STYLE_FUNCTION_PROPERTIES
#include <mbgl/util/variant.hpp>
#include <vector>
namespace mbgl {
template <typename T>
struct ConstantFunction {
inline ConstantFunction(const T &value) : value(value) {}
inline T evaluate(float) const { return value; }
private:
const T value;
};
template <typename T>
struct LinearFunction {
inline LinearFunction(const T &value, float z_base, float slope, const T &min, const T &max)
: value(value), min(min), max(max), z_base(z_base), slope(slope) {}
T evaluate(float z) const;
private:
const T value, min, max;
const float z_base, slope;
};
template <typename T>
struct ExponentialFunction {
inline ExponentialFunction(const T &value, float z_base, float exp_base, float slope, const T &min,
const T &max)
: value(value), min(min), max(max), z_base(z_base), exp_base(exp_base), slope(slope) {}
T evaluate(float z) const;
private:
const T value, min, max;
const float z_base, exp_base, slope;
};
template <typename T>
struct StopsFunction {
inline StopsFunction(const std::vector<std::pair<float, T>> &values) : values(values) {}
T evaluate(float z) const;
private:
const std::vector<std::pair<float, T>> values;
};
template <typename T>
using Function = util::variant<
std::false_type,
ConstantFunction<T>,
LinearFunction<T>,
ExponentialFunction<T>,
StopsFunction<T>
>;
template <typename T>
struct FunctionEvaluator {
typedef T result_type;
inline FunctionEvaluator(float z) : z(z) {}
inline result_type operator()(const std::false_type &) {
return result_type();
}
template <template <typename> class Fn>
inline result_type operator()(const Fn<T>& fn) {
return fn.evaluate(z);
}
private:
float z;
};
}
#endif
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