1 files changed, 66 insertions, 0 deletions
diff --git a/include/mbgl/style/expression/parse/case.hpp b/include/mbgl/style/expression/parse/case.hpp
new file mode 100644
index 0000000000..8dfa390328
--- /dev/null
+++ b/include/mbgl/style/expression/parse/case.hpp
@@ -0,0 +1,66 @@
+#pragma once
+
+#include <mbgl/style/conversion.hpp>
+#include <mbgl/style/expression/case.hpp>
+#include <mbgl/style/expression/parsing_context.hpp>
+#include <mbgl/style/expression/type.hpp>
+
+namespace mbgl {
+namespace style {
+namespace expression {
+
+struct ParseCase {
+    template <class V>
+    static ParseResult parse(const V& value, ParsingContext ctx) {
+        using namespace mbgl::style::conversion;
+        
+        assert(isArray(value));
+        auto length = arrayLength(value);
+        if (length < 4) {
+            ctx.error("Expected at least 3 arguments, but found only " + std::to_string(length - 1) + ".");
+            return ParseResult();
+        }
+        
+        // Expect even-length array: ["case", 2 * (n pairs)..., otherwise]
+        if (length % 2 != 0) {
+            ctx.error("Expected an odd number of arguments");
+            return ParseResult();
+        }
+        
+        optional<type::Type> outputType = ctx.expected;
+
+        std::vector<Case::Branch> branches;
+        for (size_t i = 1; i + 1 < length; i += 2) {
+            auto test = parseExpression(arrayMember(value, i), ParsingContext(ctx, i, {type::Boolean}));
+            if (!test) {
+                return test;
+            }
+
+            auto output = parseExpression(arrayMember(value, i + 1), ParsingContext(ctx, i + 1, outputType));
+            if (!output) {
+                return output;
+            }
+            
+            if (!outputType) {
+                outputType = (*output)->getType();
+            }
+
+            branches.push_back(std::make_pair(std::move(*test), std::move(*output)));
+        }
+        
+        assert(outputType);
+        
+        auto otherwise = parseExpression(arrayMember(value, length - 1), ParsingContext(ctx, length - 1, outputType));
+        if (!otherwise) {
+            return otherwise;
+        }
+        
+        return ParseResult(std::make_unique<Case>(*outputType,
+                                      std::move(branches),
+                                      std::move(*otherwise)));
+    }
+};
+
+} // namespace expression
+} // namespace style
+} // namespace mbgl