1 #pragma once
2 
3 #include <mbgl/style/expression/expression.hpp>
4 #include <mbgl/style/conversion.hpp>
5 
6 #include <memory>
7 #include <vector>
8 
9 namespace mbgl {
10 namespace style {
11 namespace expression {
12 
13 /**
14  * Special form for error-coalescing coercion expressions "to-number",
15  * "to-color".  Since these coercions can fail at runtime, they accept multiple
16  * arguments, only evaluating one at a time until one succeeds.
17  */
18 class Coercion : public Expression  {
19 public:
20     Coercion(type::Type type_, std::vector<std::unique_ptr<Expression>> inputs_);
21 
22     static ParseResult parse(const mbgl::style::conversion::Convertible& value, ParsingContext& ctx);
23 
24     EvaluationResult evaluate(const EvaluationContext& params) const override;
25     void eachChild(const std::function<void(const Expression&)>& visit) const override;
26 
27     bool operator==(const Expression& e) const override;
28 
29     std::vector<optional<Value>> possibleOutputs() const override;
30 
31     std::string getOperator() const override;
32 private:
33     EvaluationResult (*coerceSingleValue) (const Value& v);
34     std::vector<std::unique_ptr<Expression>> inputs;
35 };
36 
37 } // namespace expression
38 } // namespace style
39 } // namespace mbgl
40 
41