fe2a26225f
This paves the way for updates to filter and layout properties to trigger a source reload, without each SDK having to participate in the implementation.
54 lines
1.6 KiB
C++
54 lines
1.6 KiB
C++
#pragma once
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#include <mbgl/util/variant.hpp>
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#include <mbgl/style/function.hpp>
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namespace mbgl {
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namespace style {
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class Undefined {};
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inline bool operator==(const Undefined&, const Undefined&) { return true; }
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inline bool operator!=(const Undefined&, const Undefined&) { return false; }
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template <class T>
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class PropertyValue {
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private:
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using Value = variant<Undefined, T, Function<T>>;
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Value value;
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template <class S> friend bool operator==(const PropertyValue<S>&, const PropertyValue<S>&);
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public:
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PropertyValue() : value() {}
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PropertyValue( T constant) : value(constant) {}
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PropertyValue(Function<T> function) : value(function) {}
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bool isUndefined() const { return value.which() == 0; }
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bool isConstant() const { return value.which() == 1; }
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bool isFunction() const { return value.which() == 2; }
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const T & asConstant() const { return value.template get< T >(); }
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const Function<T>& asFunction() const { return value.template get<Function<T>>(); }
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explicit operator bool() const { return !isUndefined(); };
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template <typename Visitor>
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static auto visit(const PropertyValue<T>& value, Visitor&& visitor) {
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return Value::visit(value.value, visitor);
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}
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};
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template <class T>
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bool operator==(const PropertyValue<T>& lhs, const PropertyValue<T>& rhs) {
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return lhs.value == rhs.value;
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}
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template <class T>
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bool operator!=(const PropertyValue<T>& lhs, const PropertyValue<T>& rhs) {
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return !(lhs == rhs);
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}
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} // namespace style
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} // namespace mbgl
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