1 files changed, 75 insertions, 0 deletions
diff --git a/include/mbgl/style/filter_expression_private.hpp b/include/mbgl/style/filter_expression_private.hpp
new file mode 100644
index 0000000000..9379d250ba
--- /dev/null
+++ b/include/mbgl/style/filter_expression_private.hpp
@@ -0,0 +1,75 @@
+#ifndef MBGL_STYLE_FILTER_EXPRESSION_PRIVATE
+#define MBGL_STYLE_FILTER_EXPRESSION_PRIVATE
+
+#include "filter_expression.hpp"
+#include "filter_comparison_private.hpp"
+
+namespace mbgl {
+
+template <typename Extractor>
+bool FilterExpression::compare(const Extractor &extractor) const {
+    if (type != GeometryType::Any && extractor.getType() != type && extractor.getType() != GeometryType::Any) {
+        return false;
+    }
+
+    switch (op) {
+    case Operator::And:
+        for (const FilterComparison &comparison : comparisons) {
+            if (!comparison.compare(extractor)) {
+                return false;
+            }
+        }
+        for (const FilterExpression &expression: expressions) {
+            if (!expression.compare(extractor)) {
+                return false;
+            }
+        }
+        return true;
+    case Operator::Or:
+        for (const FilterComparison &comparison : comparisons) {
+            if (comparison.compare(extractor)) {
+                return true;
+            }
+        }
+        for (const FilterExpression &expression: expressions) {
+            if (expression.compare(extractor)) {
+                return true;
+            }
+        }
+        return false;
+    case Operator::Xor: {
+        int count = 0;
+        for (const FilterComparison &comparison : comparisons) {
+            count += comparison.compare(extractor);
+            if (count > 1) {
+                return false;
+            }
+        }
+        for (const FilterExpression &expression: expressions) {
+            count += expression.compare(extractor);
+            if (count > 1) {
+                return false;
+            }
+        }
+        return count == 1;
+    }
+    case Operator::Nor:
+        for (const FilterComparison &comparison : comparisons) {
+            if (comparison.compare(extractor)) {
+                return false;
+            }
+        }
+        for (const FilterExpression &expression: expressions) {
+            if (expression.compare(extractor)) {
+                return false;
+            }
+        }
+        return true;
+    default:
+        return true;
+    }
+}
+
+}
+
+#endif