diff options
Diffstat (limited to 'src/mbgl/style/expression/check_subtype.cpp')
-rw-r--r-- | src/mbgl/style/expression/check_subtype.cpp | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/src/mbgl/style/expression/check_subtype.cpp b/src/mbgl/style/expression/check_subtype.cpp new file mode 100644 index 0000000000..04a1643f0c --- /dev/null +++ b/src/mbgl/style/expression/check_subtype.cpp @@ -0,0 +1,60 @@ +#include <string> +#include <mbgl/style/expression/check_subtype.hpp> + +namespace mbgl { +namespace style { +namespace expression { +namespace type { + +std::string errorMessage(const Type& expected, const Type& t) { + return {"Expected " + toString(expected) + " but found " + toString(t) + " instead."}; +} + +optional<std::string> checkSubtype(const Type& expected, const Type& t) { + if (t.is<ErrorType>()) return {}; + + optional<std::string> result = expected.match( + [&] (const Array& expectedArray) -> optional<std::string> { + if (!t.is<Array>()) { return {errorMessage(expected, t)}; } + const auto& actualArray = t.get<Array>(); + const auto err = checkSubtype(expectedArray.itemType, actualArray.itemType); + if (err) return { errorMessage(expected, t) }; + if (expectedArray.N && expectedArray.N != actualArray.N) return { errorMessage(expected, t) }; + return {}; + }, + [&] (const ValueType&) -> optional<std::string> { + if (t.is<ValueType>()) return {}; + + const Type members[] = { + Null, + Boolean, + Number, + String, + Object, + Color, + Array(Value) + }; + + for (const auto& member : members) { + const auto err = checkSubtype(member, t); + if (!err) { + return {}; + } + } + return { errorMessage(expected, t) }; + }, + [&] (const auto&) -> optional<std::string> { + if (expected != t) { + return { errorMessage(expected, t) }; + } + return {}; + } + ); + + return result; +} + +} // namespace type +} // namespace expression +} // namespace style +} // namespace mbgl |