1 files changed, 68 insertions, 0 deletions
diff --git a/src/mbgl/style/property_expression.cpp b/src/mbgl/style/property_expression.cpp
new file mode 100644
index 0000000000..9ebecc4b40
--- /dev/null
+++ b/src/mbgl/style/property_expression.cpp
@@ -0,0 +1,68 @@
+#include <mbgl/style/property_expression.hpp>
+
+namespace mbgl {
+namespace style {
+
+PropertyExpressionBase::PropertyExpressionBase(std::unique_ptr<expression::Expression> expression_)
+    : expression(std::move(expression_)),
+      zoomCurve(expression::findZoomCurveChecked(expression.get())) {
+    isZoomConstant_ = expression::isZoomConstant(*expression);
+    isFeatureConstant_ = expression::isFeatureConstant(*expression);
+}
+
+bool PropertyExpressionBase::isZoomConstant() const noexcept {
+    return isZoomConstant_;
+}
+
+bool PropertyExpressionBase::isFeatureConstant() const noexcept {
+    return isFeatureConstant_;
+}
+
+bool PropertyExpressionBase::canEvaluateWith(const expression::EvaluationContext& context) const noexcept {
+    if (context.zoom) {
+        if (context.feature != nullptr) {
+            return !isFeatureConstant();
+        }
+        return !isZoomConstant() && isFeatureConstant();
+    }
+
+    if (context.feature != nullptr) {
+        return isZoomConstant() && !isFeatureConstant();
+    }
+
+    return true;
+}
+
+float PropertyExpressionBase::interpolationFactor(const Range<float>& inputLevels, const float inputValue) const noexcept {
+    return zoomCurve.match(
+        [](std::nullptr_t) {
+            assert(false);
+            return 0.0f;
+        },
+        [&](const expression::Interpolate* z) {
+            return z->interpolationFactor(Range<double> { inputLevels.min, inputLevels.max }, inputValue);
+        },
+        [](const expression::Step*) {
+            return 0.0f;
+        }
+    );
+}
+
+Range<float> PropertyExpressionBase::getCoveringStops(const float lower, const float upper) const noexcept {
+    return zoomCurve.match(
+        [](std::nullptr_t) {
+            assert(false);
+            return Range<float>(0.0f, 0.0f);
+        },
+        [&](auto z) {
+            return z->getCoveringStops(lower, upper);
+        }
+    );
+}
+
+const expression::Expression& PropertyExpressionBase::getExpression() const noexcept {
+    return *expression;
+}
+
+} // namespace style
+} // namespace mbgl