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#pragma once
#include <mbgl/style/expression/expression.hpp>
#include <mbgl/style/expression/value.hpp>
#include <mbgl/style/expression/is_constant.hpp>
#include <mbgl/style/expression/interpolate.hpp>
#include <mbgl/style/expression/step.hpp>
#include <mbgl/style/expression/find_zoom_curve.hpp>
#include <mbgl/util/range.hpp>
namespace mbgl {
namespace style {
template <class T>
class PropertyExpression {
public:
// Second parameter to be used only for conversions from legacy functions.
PropertyExpression(std::unique_ptr<expression::Expression> expression_, optional<T> defaultValue_ = {})
: expression(std::move(expression_)),
defaultValue(std::move(defaultValue_)),
zoomCurve(expression::findZoomCurveChecked(expression.get())) {
}
bool isZoomConstant() const { return expression::isZoomConstant(*expression); }
bool isFeatureConstant() const { return expression::isFeatureConstant(*expression); }
T evaluate(float zoom) const {
assert(isFeatureConstant());
const expression::EvaluationResult result = expression->evaluate(expression::EvaluationContext(zoom, nullptr));
if (result) {
const optional<T> typed = expression::fromExpressionValue<T>(*result);
return typed ? *typed : defaultValue ? *defaultValue : T();
}
return defaultValue ? *defaultValue : T();
}
template <class Feature>
T evaluate(const Feature& feature, T finalDefaultValue) const {
assert(isZoomConstant());
assert(!isFeatureConstant());
const expression::EvaluationResult result = expression->evaluate(expression::EvaluationContext(&feature));
if (result) {
const optional<T> typed = expression::fromExpressionValue<T>(*result);
return typed ? *typed : defaultValue ? *defaultValue : finalDefaultValue;
}
return defaultValue ? *defaultValue : finalDefaultValue;
}
template <class Feature>
T evaluate(float zoom, const Feature& feature, T finalDefaultValue) const {
assert(!isFeatureConstant());
const expression::EvaluationResult result = expression->evaluate(expression::EvaluationContext({zoom}, &feature));
if (result) {
const optional<T> typed = expression::fromExpressionValue<T>(*result);
return typed ? *typed : defaultValue ? *defaultValue : finalDefaultValue;
}
return defaultValue ? *defaultValue : finalDefaultValue;
}
float interpolationFactor(const Range<float>& inputLevels, const float inputValue) const {
return zoomCurve.match(
[](std::nullptr_t) {
assert(false);
return 0.0f;
},
[&](const expression::Interpolate* z) {
return z->interpolationFactor(Range<double> { inputLevels.min, inputLevels.max }, inputValue);
},
[&](const expression::Step*) {
return 0.0f;
}
);
}
Range<float> getCoveringStops(const float lower, const float upper) const {
return zoomCurve.match(
[](std::nullptr_t) {
assert(false);
return Range<float>(0.0f, 0.0f);
},
[&](auto z) {
return z->getCoveringStops(lower, upper);
}
);
}
// Return the range obtained by evaluating the function at each of the zoom levels in zoomRange
template <class Feature>
Range<T> evaluate(const Range<float>& zoomRange, const Feature& feature, T finalDefaultValue) {
return Range<T> {
evaluate(zoomRange.min, feature, finalDefaultValue),
evaluate(zoomRange.max, feature, finalDefaultValue)
};
}
std::vector<optional<T>> possibleOutputs() const {
return expression::fromExpressionValues<T>(expression->possibleOutputs());
}
const expression::Expression& getExpression() const { return *expression; }
bool useIntegerZoom = false;
friend bool operator==(const PropertyExpression& lhs,
const PropertyExpression& rhs) {
return *lhs.expression == *rhs.expression;
}
private:
std::shared_ptr<const expression::Expression> expression;
optional<T> defaultValue;
variant<std::nullptr_t, const expression::Interpolate*, const expression::Step*> zoomCurve;
};
} // namespace style
} // namespace mbgl
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