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#include <mbgl/style/expression/find_zoom_curve.hpp>
#include <mbgl/style/expression/compound_expression.hpp>
#include <mbgl/style/expression/let.hpp>
#include <mbgl/style/expression/coalesce.hpp>
#include <mbgl/style/expression/is_constant.hpp>
#include <mbgl/util/variant.hpp>
#include <mbgl/util/optional.hpp>
namespace mbgl {
namespace style {
namespace expression {
optional<variant<const Interpolate*, const Step*, ParsingError>> findZoomCurve(const expression::Expression* e) {
optional<variant<const Interpolate*, const Step*, ParsingError>> result;
switch (e->getKind()) {
case Kind::Let: {
auto let = static_cast<const Let*>(e);
result = findZoomCurve(let->getResult());
break;
}
case Kind::Coalesce: {
auto coalesce = static_cast<const Coalesce*>(e);
std::size_t length = coalesce->getLength();
for (std::size_t i = 0; i < length; i++) {
result = findZoomCurve(coalesce->getChild(i));
if (result) {
break;
}
}
break;
}
case Kind::Interpolate: {
auto curve = static_cast<const Interpolate*>(e);
if (curve->getInput()->getKind() == Kind::CompoundExpression) {
auto z = static_cast<CompoundExpression*>(curve->getInput().get());
if (z && z->getOperator() == "zoom") {
result = {curve};
}
}
break;
}
case Kind::Step: {
auto step = static_cast<const Step*>(e);
if (step->getInput()->getKind() == Kind::CompoundExpression) {
auto z = static_cast<CompoundExpression*>(step->getInput().get());
if (z && z->getOperator() == "zoom") {
result = {step};
}
}
break;
}
default:
break;
}
if (result && result->is<ParsingError>()) {
return result;
}
e->eachChild([&](const Expression& child) {
optional<variant<const Interpolate*, const Step*, ParsingError>> childResult(findZoomCurve(&child));
if (childResult) {
if (childResult->is<ParsingError>()) {
result = childResult;
} else if (!result && childResult) {
result = {ParsingError {
R"("zoom" expression may only be used as input to a top-level "step" or "interpolate" expression.)", ""
}};
} else if (result && childResult && result != childResult) {
result = {ParsingError {
R"(Only one zoom-based "step" or "interpolate" subexpression may be used in an expression.)", ""
}};
}
}
});
return result;
}
variant<std::nullptr_t, const Interpolate*, const Step*> findZoomCurveChecked(const expression::Expression* e) {
if (isZoomConstant(*e)) {
return nullptr;
}
return findZoomCurve(e)->match(
[](const ParsingError&) -> variant<std::nullptr_t, const Interpolate*, const Step*> {
assert(false);
return nullptr;
},
[](auto zoomCurve) -> variant<std::nullptr_t, const Interpolate*, const Step*> {
return zoomCurve;
}
);
}
} // namespace expression
} // namespace style
} // namespace mbgl
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