diff options
Diffstat (limited to 'src/mbgl/style/expression/find_zoom_curve.cpp')
-rw-r--r-- | src/mbgl/style/expression/find_zoom_curve.cpp | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/src/mbgl/style/expression/find_zoom_curve.cpp b/src/mbgl/style/expression/find_zoom_curve.cpp new file mode 100644 index 0000000000..5d39e0791e --- /dev/null +++ b/src/mbgl/style/expression/find_zoom_curve.cpp @@ -0,0 +1,76 @@ +#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/util/variant.hpp> +#include <mbgl/util/optional.hpp> + +namespace mbgl { +namespace style { +namespace expression { + +optional<variant<const InterpolateBase*, const Step*, ParsingError>> findZoomCurve(const expression::Expression* e) { + optional<variant<const InterpolateBase*, const Step*, ParsingError>> result; + + if (auto let = dynamic_cast<const Let*>(e)) { + result = findZoomCurve(let->getResult()); + } else if (auto coalesce = dynamic_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; + } + } + } else if (auto curve = dynamic_cast<const InterpolateBase*>(e)) { + auto z = dynamic_cast<CompoundExpressionBase*>(curve->getInput().get()); + if (z && z->getName() == "zoom") { + result = {curve}; + } + } else if (auto step = dynamic_cast<const Step*>(e)) { + auto z = dynamic_cast<CompoundExpressionBase*>(step->getInput().get()); + if (z && z->getName() == "zoom") { + result = {step}; + } + } + + if (result && result->is<ParsingError>()) { + return result; + } + + e->eachChild([&](const Expression& child) { + optional<variant<const InterpolateBase*, 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<const InterpolateBase*, const Step*> findZoomCurveChecked(const expression::Expression* e) { + return findZoomCurve(e)->match( + [](const ParsingError&) -> variant<const InterpolateBase*, const Step*> { + assert(false); + return {}; + }, + [](auto zoomCurve) -> variant<const InterpolateBase*, const Step*> { + return {std::move(zoomCurve)}; + } + ); +} + +} // namespace expression +} // namespace style +} // namespace mbgl |