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#pragma once
#include <mbgl/style/property_value.hpp>
#include <mbgl/style/data_driven_property_value.hpp>
#include <mbgl/style/property_evaluator.hpp>
#include <mbgl/style/data_driven_property_evaluator.hpp>
#include <mbgl/util/indexed_tuple.hpp>
namespace mbgl {
namespace style {
class PropertyEvaluationParameters;
template <class T>
class LayoutProperty {
public:
using UnevaluatedType = PropertyValue<T>;
using EvaluatorType = PropertyEvaluator<T>;
using PossiblyEvaluatedType = T;
using Type = T;
};
template <class T>
class DataDrivenLayoutProperty {
public:
using UnevaluatedType = DataDrivenPropertyValue<T>;
using EvaluatorType = DataDrivenPropertyEvaluator<T>;
using PossiblyEvaluatedType = PossiblyEvaluatedPropertyValue<T>;
using Type = T;
};
template <class... Ps>
class LayoutProperties {
public:
using Properties = TypeList<Ps...>;
template <class TypeList>
using Tuple = IndexedTuple<Properties, TypeList>;
/*
For layout properties we implement a two step evaluation process: if you have a zoom level,
you can evaluate a set of unevaluated property values, producing a set of possibly evaluated
values, where undefined, constant, or camera function values have been fully evaluated, and
source or composite function values have not.
Once you also have a particular feature, you can evaluate that set of possibly evaluated values
fully, producing a set of fully evaluated values.
This is in theory maximally efficient in terms of avoiding repeated evaluation of camera
functions, though it's more of a historical accident than a purposeful optimization.
*/
using UnevaluatedTypes = TypeList<typename Ps::UnevaluatedType...>;
using PossiblyEvaluatedTypes = TypeList<typename Ps::PossiblyEvaluatedType...>;
using EvaluatedTypes = TypeList<typename Ps::Type...>;
class Evaluated : public Tuple<EvaluatedTypes> {
public:
using Tuple<EvaluatedTypes>::Tuple;
};
class PossiblyEvaluated : public Tuple<PossiblyEvaluatedTypes> {
public:
using Tuple<PossiblyEvaluatedTypes>::Tuple;
template <class T>
static T evaluate(float, const GeometryTileFeature&, const T& t, const T&) {
return t;
}
template <class T>
static T evaluate(float z, const GeometryTileFeature& feature,
const PossiblyEvaluatedPropertyValue<T>& v, const T& defaultValue) {
return v.match(
[&] (const T& t) {
return t;
},
[&] (const SourceFunction<T>& t) {
return t.evaluate(feature, defaultValue);
},
[&] (const CompositeFunction<T>& t) {
return t.evaluate(z, feature, defaultValue);
});
}
template <class P>
auto evaluate(float z, const GeometryTileFeature& feature) const {
return evaluate(z, feature, this->template get<P>(), P::defaultValue());
}
Evaluated evaluate(float z, const GeometryTileFeature& feature) const {
return Evaluated {
evaluate<Ps>(z, feature)...
};
}
};
class Unevaluated : public Tuple<UnevaluatedTypes> {
public:
using Tuple<UnevaluatedTypes>::Tuple;
};
template <class P>
auto evaluate(const PropertyEvaluationParameters& parameters) const {
using Evaluator = typename P::EvaluatorType;
return unevaluated.template get<P>()
.evaluate(Evaluator(parameters, P::defaultValue()));
}
PossiblyEvaluated evaluate(const PropertyEvaluationParameters& parameters) const {
return PossiblyEvaluated {
evaluate<Ps>(parameters)...
};
}
Unevaluated unevaluated;
};
} // namespace style
} // namespace mbgl
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