is_constant.hpp

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#pragma once
 
#include <mbgl/style/expression/expression.hpp>
#include <mbgl/style/expression/compound_expression.hpp>
 
namespace mbgl {
namespace style {
namespace expression {
 
template <typename T>
bool isGlobalPropertyConstant(const Expression& expression, const T& properties) {
    if (expression.getKind() == Kind::CompoundExpression) {
        auto e = static_cast<const CompoundExpression*>(&expression);
        for (const std::string& property : properties) {
            if (e->getOperator() == property) {
                return false;
            }
        }
    }
 
    bool isConstant = true;
    expression.eachChild([&](const Expression& e) {
        if (isConstant && !isGlobalPropertyConstant(e, properties)) {
            isConstant = false;
        }
    });
    return isConstant;
}
 
bool isFeatureConstant(const Expression& expression);
bool isZoomConstant(const Expression& e);
 
bool isRuntimeConstant(const Expression& e);
 
} // namespace expression
} // namespace style
} // namespace mbgl