coalesce.hpp

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#pragma once
 
#include <mbgl/style/expression/expression.hpp>
#include <mbgl/style/expression/parsing_context.hpp>
#include <mbgl/style/conversion.hpp>
 
#include <memory>
#include <map>
 
namespace mbgl {
namespace style {
namespace expression {
 
class Coalesce : public Expression {
public:
    using Args = std::vector<std::unique_ptr<Expression>>;
    Coalesce(const type::Type& type_, Args args_) :
        Expression(Kind::Coalesce, type_),
        args(std::move(args_))
    {}
 
    static ParseResult parse(const mbgl::style::conversion::Convertible& value, ParsingContext& ctx);
 
 
    EvaluationResult evaluate(const EvaluationContext& params) const override;
    
    void eachChild(const std::function<void(const Expression&)>& visit) const override;
 
    bool operator==(const Expression& e) const override;
 
    std::vector<std::optional<Value>> possibleOutputs() const override;
 
    std::size_t getLength() const {
        return args.size();
    }
    
    Expression* getChild(std::size_t i) const {
        return args.at(i).get();
    }
    
    std::string getOperator() const override { return "coalesce"; }
private:
    Args args;
};
 
} // namespace expression
} // namespace style
} // namespace mbgl