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MapLibreParticleLab/include/mln/style/property_value.hpp
Bart Louwers 2a8ebc4906 core: rename mbgl directories to mln (#4511)
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
2026-08-22 20:50:14 +02:00

79 lines
2.7 KiB
C++

#pragma once
#include <mln/util/variant.hpp>
#include <mln/style/undefined.hpp>
#include <mln/style/property_expression.hpp>
namespace mln {
namespace style {
template <class T>
class PropertyValue {
private:
using Value = variant<Undefined, T, PropertyExpression<T>>;
Value value;
friend bool operator==(const PropertyValue& lhs, const PropertyValue& rhs) noexcept {
return lhs.value == rhs.value;
}
friend bool operator!=(const PropertyValue& lhs, const PropertyValue& rhs) noexcept { return !(lhs == rhs); }
public:
PropertyValue() = default;
PropertyValue(T constant)
: value(std::forward<T>(constant)) {}
PropertyValue(PropertyExpression<T> expression) noexcept
: value(std::move(expression)) {}
bool isUndefined() const noexcept { return value.template is<Undefined>(); }
bool isConstant() const noexcept { return value.template is<T>(); }
bool isExpression() const noexcept { return value.template is<PropertyExpression<T>>(); }
bool isDataDriven() const noexcept {
return value.match([](const Undefined&) { return false; },
[](const T&) { return false; },
[](const PropertyExpression<T>& fn) { return !fn.isFeatureConstant(); });
}
bool isZoomConstant() const noexcept {
return value.match([](const Undefined&) { return true; },
[](const T&) { return true; },
[](const PropertyExpression<T>& fn) { return fn.isZoomConstant(); });
}
const T& asConstant() const noexcept { return value.template get<T>(); }
PropertyExpression<T>& asExpression() noexcept { return value.template get<PropertyExpression<T>>(); }
const PropertyExpression<T>& asExpression() const noexcept { return value.template get<PropertyExpression<T>>(); }
template <class... Ts>
auto match(Ts&&... ts) const {
return value.match(std::forward<Ts>(ts)...);
}
template <typename Evaluator>
auto evaluate(const Evaluator& evaluator, TimePoint = {}) const {
return Value::visit(value, evaluator);
}
bool hasDataDrivenPropertyDifference(const PropertyValue<T>& other) const noexcept {
return *this != other && (isDataDriven() || other.isDataDriven());
}
using Dependency = style::expression::Dependency;
Dependency getDependencies() const noexcept {
return value.match([](const Undefined&) { return Dependency::None; },
[](const T&) { return Dependency::None; },
[](const PropertyExpression<T>& ex) { return ex.getDependencies(); });
}
};
} // namespace style
} // namespace mln