78 lines
2.5 KiB
C++
78 lines
2.5 KiB
C++
#pragma once
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#include <mbgl/style/expression/is_constant.hpp>
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#include <mbgl/style/function/convert.hpp>
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#include <mbgl/style/function/exponential_stops.hpp>
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#include <mbgl/style/function/interval_stops.hpp>
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#include <mbgl/style/function/categorical_stops.hpp>
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#include <mbgl/style/function/identity_stops.hpp>
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#include <mbgl/util/interpolate.hpp>
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#include <mbgl/util/variant.hpp>
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#include <string>
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namespace mbgl {
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namespace style {
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template <class T>
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class SourceFunction {
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public:
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using Stops = std::conditional_t<
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util::Interpolatable<T>::value,
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variant<
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ExponentialStops<T>,
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IntervalStops<T>,
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CategoricalStops<T>,
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IdentityStops<T>>,
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variant<
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IntervalStops<T>,
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CategoricalStops<T>,
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IdentityStops<T>>>;
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SourceFunction(std::unique_ptr<expression::Expression> expression_)
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: expression(std::move(expression_))
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{
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assert(expression::isZoomConstant(*expression));
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assert(!expression::isFeatureConstant(*expression));
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}
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SourceFunction(std::string property_, Stops stops_, optional<T> defaultValue_ = {})
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: property(std::move(property_)),
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stops(std::move(stops_)),
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defaultValue(std::move(defaultValue_)),
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expression(stops.match([&] (const IdentityStops<T>&) {
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return expression::Convert::fromIdentityFunction(expression::valueTypeToExpressionType<T>(), property);
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}, [&] (const auto& s) {
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return expression::Convert::toExpression(property, s);
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}))
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{}
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template <class Feature>
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T evaluate(const Feature& feature, T finalDefaultValue) const {
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const expression::EvaluationResult result = expression->evaluate(expression::EvaluationContext(&feature));
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if (result) {
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const optional<T> typed = expression::fromExpressionValue<T>(*result);
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return typed ? *typed : defaultValue ? *defaultValue : finalDefaultValue;
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}
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return defaultValue ? *defaultValue : finalDefaultValue;
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}
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friend bool operator==(const SourceFunction& lhs,
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const SourceFunction& rhs) {
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return *lhs.expression == *rhs.expression;
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}
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bool useIntegerZoom = false;
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// retained for compatibility with pre-expression function API
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std::string property;
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Stops stops;
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optional<T> defaultValue;
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private:
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std::shared_ptr<expression::Expression> expression;
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};
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} // namespace style
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} // namespace mbgl
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