diff options
Diffstat (limited to 'include/mbgl/style')
22 files changed, 335 insertions, 393 deletions
diff --git a/include/mbgl/style/conversion.hpp b/include/mbgl/style/conversion.hpp index 71c2cec237..2c83d1561b 100644 --- a/include/mbgl/style/conversion.hpp +++ b/include/mbgl/style/conversion.hpp @@ -1,306 +1,26 @@ #pragma once -#include <mbgl/util/optional.hpp> -#include <mbgl/util/feature.hpp> -#include <mbgl/util/geojson.hpp> - #include <string> namespace mbgl { namespace style { namespace conversion { -/* - The `conversion` namespace defines conversions from JSON structures conforming to the schema defined by - the Mapbox Style Specification, to the various C++ types that form the C++ model of that domain: - - * `std::unique_ptr<Source>` - * `std::unique_ptr<Layer>` - * `Filter` - * `PropertyValue<T>` - - A single template function serves as the public interface: - - template <class T> - optional<T> convert(const Convertible& input, Error& error); - - Where `T` is one of the above types. If the conversion fails, the result is empty, and the - error parameter includes diagnostic text suitable for presentation to a library user. Otherwise, - a filled optional is returned. - - `Convertible` is a type that encapsulates a special form of polymorphism over various underlying types that - can serve as input to the conversion algorithm. For instance, on macOS, we need to support - conversion from both RapidJSON types, and a JSON structure represented with `NSArray`/`NSDictionary`/etc. - On Qt, we need to support conversion from RapidJSON types and QVariant. - - We don't want to use traditional forms of polymorphism to accomplish this: - - * Compile time polymorphism using a template parameter for the actual value type leads to - excessive code bloat and long compile times. - * Runtime polymorphism using virtual methods requires extra heap allocation and ubiquitous - use of std::unique_ptr, unsuitable for this performance-sensitive code. - - Therefore, we're using a custom implementation of runtime polymorphism where we manually create and - dispatch through a table of function pointers (vtable), while keeping the storage for any of the possible - underlying types inline on the stack, using `std::aligned_storage`. - - For a given underlying type T, an explicit specialization of `ConversionTraits<T>` must be provided. This - specialization must provide the following static methods: - - * `isUndefined(v)` -- returns a boolean indication whether `v` is undefined or a JSON null - - * `isArray(v)` -- returns a boolean indicating whether `v` represents a JSON array - * `arrayLength(v)` -- called only if `isArray(v)`; returns a size_t length - * `arrayMember(v)` -- called only if `isArray(v)`; returns `V` or `V&` - - * `isObject(v)` -- returns a boolean indicating whether `v` represents a JSON object - * `objectMember(v, name)` -- called only if `isObject(v)`; `name` is `const char *`; return value: - * is true when evaluated in a boolean context iff the named member exists - * is convertable to a `V` or `V&` when dereferenced - * `eachMember(v, [] (const std::string&, const V&) -> optional<Error> {...})` -- called - only if `isObject(v)`; calls the provided lambda once for each key and value of the object; - short-circuits if any call returns an `Error` - - * `toBool(v)` -- returns `optional<bool>`, absence indicating `v` is not a JSON boolean - * `toNumber(v)` -- returns `optional<float>`, absence indicating `v` is not a JSON number - * `toDouble(v)` -- returns `optional<double>`, absence indicating `v` is not a JSON number - * `toString(v)` -- returns `optional<std::string>`, absence indicating `v` is not a JSON string - * `toValue(v)` -- returns `optional<Value>`, a variant type, for generic conversion, - absence indicating `v` is not a boolean, number, or string. Numbers should be converted to - unsigned integer, signed integer, or floating point, in descending preference. - - In addition, the type T must be move-constructable. And finally, `Convertible::Storage`, a typedef for - `std::aligned_storage_t`, must be large enough to satisfy the memory requirements for any of the - possible underlying types. (A static assert will fail if this is not the case.) - - `Convertible` itself is movable, but not copyable. A moved-from `Convertible` is in an invalid state; - you must not do anything with it except let it go out of scope. -*/ +// This is a forward-declaration only header intended to minimize dependencies and to improve +// compilation speed. In order to specialize implementations and get access to the actual +// implementation, include <mbgl/style/conversion_impl.hpp>. struct Error { std::string message; }; template <typename T> class ConversionTraits; -class Convertible { -public: - template <typename T> - Convertible(T&& value) : vtable(vtableForType<std::decay_t<T>>()) { - static_assert(sizeof(Storage) >= sizeof(std::decay_t<T>), "Storage must be large enough to hold value type"); - new (static_cast<void*>(&storage)) std::decay_t<T>(std::forward<T>(value)); - } - - Convertible(Convertible&& v) - : vtable(v.vtable) - { - if (vtable) { - vtable->move(std::move(v.storage), this->storage); - } - } - - ~Convertible() { - if (vtable) { - vtable->destroy(storage); - } - } - - Convertible& operator=(Convertible&& v) { - if (vtable) { - vtable->destroy(storage); - } - vtable = v.vtable; - if (vtable) { - vtable->move(std::move(v.storage), this->storage); - } - v.vtable = nullptr; - return *this; - } - - Convertible() = delete; - Convertible(const Convertible&) = delete; - Convertible& operator=(const Convertible&) = delete; - - friend inline bool isUndefined(const Convertible& v) { - assert(v.vtable); - return v.vtable->isUndefined(v.storage); - } - - friend inline bool isArray(const Convertible& v) { - assert(v.vtable); - return v.vtable->isArray(v.storage); - } - - friend inline std::size_t arrayLength(const Convertible& v) { - assert(v.vtable); - return v.vtable->arrayLength(v.storage); - } - - friend inline Convertible arrayMember(const Convertible& v, std::size_t i) { - assert(v.vtable); - return v.vtable->arrayMember(v.storage, i); - } - - friend inline bool isObject(const Convertible& v) { - assert(v.vtable); - return v.vtable->isObject(v.storage); - } - - friend inline optional<Convertible> objectMember(const Convertible& v, const char * name) { - assert(v.vtable); - return v.vtable->objectMember(v.storage, name); - } - - friend inline optional<Error> eachMember(const Convertible& v, const std::function<optional<Error> (const std::string&, const Convertible&)>& fn) { - assert(v.vtable); - return v.vtable->eachMember(v.storage, fn); - } - - friend inline optional<bool> toBool(const Convertible& v) { - assert(v.vtable); - return v.vtable->toBool(v.storage); - } - - friend inline optional<float> toNumber(const Convertible& v) { - assert(v.vtable); - return v.vtable->toNumber(v.storage); - } - - friend inline optional<double> toDouble(const Convertible& v) { - assert(v.vtable); - return v.vtable->toDouble(v.storage); - } - - friend inline optional<std::string> toString(const Convertible& v) { - assert(v.vtable); - return v.vtable->toString(v.storage); - } - - friend inline optional<Value> toValue(const Convertible& v) { - assert(v.vtable); - return v.vtable->toValue(v.storage); - } - - friend inline optional<GeoJSON> toGeoJSON(const Convertible& v, Error& error) { - assert(v.vtable); - return v.vtable->toGeoJSON(v.storage, error); - } - -private: -#if __ANDROID__ - // Android: JSValue* or mbgl::android::Value - using Storage = std::aligned_storage_t<32, 8>; -#elif __QT__ - // Qt: JSValue* or QVariant - using Storage = std::aligned_storage_t<32, 8>; -#else - // Node: JSValue* or v8::Local<v8::Value> - // iOS/macOS: JSValue* or id - using Storage = std::aligned_storage_t<8, 8>; -#endif - - struct VTable { - void (*move) (Storage&& src, Storage& dest); - void (*destroy) (Storage&); - - bool (*isUndefined) (const Storage&); - - bool (*isArray) (const Storage&); - std::size_t (*arrayLength) (const Storage&); - Convertible (*arrayMember) (const Storage&, std::size_t); - - bool (*isObject) (const Storage&); - optional<Convertible> (*objectMember) (const Storage&, const char *); - optional<Error> (*eachMember) (const Storage&, const std::function<optional<Error> (const std::string&, const Convertible&)>&); - - optional<bool> (*toBool) (const Storage&); - optional<float> (*toNumber) (const Storage&); - optional<double> (*toDouble) (const Storage&); - optional<std::string> (*toString) (const Storage&); - optional<Value> (*toValue) (const Storage&); - - // https://github.com/mapbox/mapbox-gl-native/issues/5623 - optional<GeoJSON> (*toGeoJSON) (const Storage&, Error&); - }; - - // Extracted this function from the table below to work around a GCC bug with differing - // visibility settings for capturing lambdas: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80947 - template <typename T> - static auto vtableEachMember(const Storage& s, const std::function<optional<Error>(const std::string&, const Convertible&)>& fn) { - return ConversionTraits<T>::eachMember(reinterpret_cast<const T&>(s), [&](const std::string& k, T&& v) { - return fn(k, Convertible(std::move(v))); - }); - } - - template <typename T> - static VTable* vtableForType() { - using Traits = ConversionTraits<T>; - static VTable vtable = { - [] (Storage&& src, Storage& dest) { - auto srcValue = reinterpret_cast<T&&>(src); - new (static_cast<void*>(&dest)) T(std::move(srcValue)); - srcValue.~T(); - }, - [] (Storage& s) { - reinterpret_cast<T&>(s).~T(); - }, - [] (const Storage& s) { - return Traits::isUndefined(reinterpret_cast<const T&>(s)); - }, - [] (const Storage& s) { - return Traits::isArray(reinterpret_cast<const T&>(s)); - }, - [] (const Storage& s) { - return Traits::arrayLength(reinterpret_cast<const T&>(s)); - }, - [] (const Storage& s, std::size_t i) { - return Convertible(Traits::arrayMember(reinterpret_cast<const T&>(s), i)); - }, - [] (const Storage& s) { - return Traits::isObject(reinterpret_cast<const T&>(s)); - }, - [] (const Storage& s, const char * key) { - optional<T> member = Traits::objectMember(reinterpret_cast<const T&>(s), key); - if (member) { - return optional<Convertible>(Convertible(std::move(*member))); - } else { - return optional<Convertible>(); - } - }, - vtableEachMember<T>, - [] (const Storage& s) { - return Traits::toBool(reinterpret_cast<const T&>(s)); - }, - [] (const Storage& s) { - return Traits::toNumber(reinterpret_cast<const T&>(s)); - }, - [] (const Storage& s) { - return Traits::toDouble(reinterpret_cast<const T&>(s)); - }, - [] (const Storage& s) { - return Traits::toString(reinterpret_cast<const T&>(s)); - }, - [] (const Storage& s) { - return Traits::toValue(reinterpret_cast<const T&>(s)); - }, - [] (const Storage& s, Error& err) { - return Traits::toGeoJSON(reinterpret_cast<const T&>(s), err); - } - }; - return &vtable; - } - - VTable* vtable; - Storage storage; -}; +class Convertible; template <class T, class Enable = void> struct Converter; -template <class T, class...Args> -optional<T> convert(const Convertible& value, Error& error, Args&&...args) { - return Converter<T>()(value, error, std::forward<Args>(args)...); -} - } // namespace conversion } // namespace style } // namespace mbgl + diff --git a/include/mbgl/style/conversion/constant.hpp b/include/mbgl/style/conversion/constant.hpp index 7d74ec42ce..40657528c4 100644 --- a/include/mbgl/style/conversion/constant.hpp +++ b/include/mbgl/style/conversion/constant.hpp @@ -1,6 +1,7 @@ #pragma once #include <mbgl/style/conversion.hpp> +#include <mbgl/style/types.hpp> #include <mbgl/util/color.hpp> #include <mbgl/util/enum.hpp> #include <mbgl/util/string.hpp> @@ -30,21 +31,7 @@ struct Converter<std::string> { template <class T> struct Converter<T, typename std::enable_if_t<std::is_enum<T>::value>> { - optional<T> operator()(const Convertible& value, Error& error) const { - optional<std::string> string = toString(value); - if (!string) { - error.message = "value must be a string"; - return nullopt; - } - - const auto result = Enum<T>::toEnum(*string); - if (!result) { - error.message = "value must be a valid enumeration value"; - return nullopt; - } - - return *result; - } + optional<T> operator()(const Convertible& value, Error& error) const; }; template <> @@ -54,23 +41,7 @@ struct Converter<Color> { template <size_t N> struct Converter<std::array<float, N>> { - optional<std::array<float, N>> operator()(const Convertible& value, Error& error) const { - if (!isArray(value) || arrayLength(value) != N) { - error.message = "value must be an array of " + util::toString(N) + " numbers"; - return nullopt; - } - - std::array<float, N> result; - for (size_t i = 0; i < N; i++) { - optional<float> n = toNumber(arrayMember(value, i)); - if (!n) { - error.message = "value must be an array of " + util::toString(N) + " numbers"; - return nullopt; - } - result[i] = *n; - } - return result; - } + optional<std::array<float, N>> operator()(const Convertible& value, Error& error) const; }; template <> diff --git a/include/mbgl/style/conversion/coordinate.hpp b/include/mbgl/style/conversion/coordinate.hpp index e11db5e32f..1346ed738a 100644 --- a/include/mbgl/style/conversion/coordinate.hpp +++ b/include/mbgl/style/conversion/coordinate.hpp @@ -2,6 +2,7 @@ #include <mbgl/style/conversion.hpp> #include <mbgl/util/geo.hpp> +#include <mbgl/util/optional.hpp> namespace mbgl { namespace style { diff --git a/include/mbgl/style/conversion/custom_geometry_source_options.hpp b/include/mbgl/style/conversion/custom_geometry_source_options.hpp index f0f505e54f..090e5b6239 100644 --- a/include/mbgl/style/conversion/custom_geometry_source_options.hpp +++ b/include/mbgl/style/conversion/custom_geometry_source_options.hpp @@ -2,6 +2,7 @@ #include <mbgl/style/conversion.hpp> #include <mbgl/style/sources/custom_geometry_source.hpp> +#include <mbgl/util/optional.hpp> namespace mbgl { namespace style { diff --git a/include/mbgl/style/conversion/filter.hpp b/include/mbgl/style/conversion/filter.hpp index 9daf6ea7a4..2d7ad0afc7 100644 --- a/include/mbgl/style/conversion/filter.hpp +++ b/include/mbgl/style/conversion/filter.hpp @@ -2,6 +2,7 @@ #include <mbgl/style/filter.hpp> #include <mbgl/style/conversion.hpp> +#include <mbgl/util/optional.hpp> namespace mbgl { namespace style { diff --git a/include/mbgl/style/conversion/function.hpp b/include/mbgl/style/conversion/function.hpp index 49825a3410..ba9acd7a3b 100644 --- a/include/mbgl/style/conversion/function.hpp +++ b/include/mbgl/style/conversion/function.hpp @@ -1,8 +1,8 @@ #pragma once #include <mbgl/style/property_expression.hpp> -#include <mbgl/style/conversion.hpp> #include <mbgl/style/conversion/constant.hpp> +#include <mbgl/style/conversion.hpp> #include <mbgl/style/expression/expression.hpp> #include <mbgl/style/expression/value.hpp> @@ -16,25 +16,7 @@ std::unique_ptr<expression::Expression> convertTokenStringToExpression(const std optional<std::unique_ptr<expression::Expression>> convertFunctionToExpression(expression::type::Type, const Convertible&, Error&, bool convertTokens); template <class T> -optional<PropertyExpression<T>> convertFunctionToExpression(const Convertible& value, Error& error, bool convertTokens) { - auto expression = convertFunctionToExpression(expression::valueTypeToExpressionType<T>(), value, error, convertTokens); - if (!expression) { - return nullopt; - } - - optional<T> defaultValue; - - auto defaultValueValue = objectMember(value, "default"); - if (defaultValueValue) { - defaultValue = convert<T>(*defaultValueValue, error); - if (!defaultValue) { - error.message = R"(wrong type for "default": )" + error.message; - return nullopt; - } - } - - return PropertyExpression<T>(std::move(*expression), defaultValue); -} +optional<PropertyExpression<T>> convertFunctionToExpression(const Convertible& value, Error& error, bool convertTokens); } // namespace conversion } // namespace style diff --git a/include/mbgl/style/conversion/geojson.hpp b/include/mbgl/style/conversion/geojson.hpp index 403c5f953b..90c1d64197 100644 --- a/include/mbgl/style/conversion/geojson.hpp +++ b/include/mbgl/style/conversion/geojson.hpp @@ -1,7 +1,8 @@ #pragma once -#include <mbgl/style/conversion.hpp> #include <mbgl/util/geojson.hpp> +#include <mbgl/style/conversion.hpp> +#include <mbgl/util/optional.hpp> namespace mbgl { namespace style { diff --git a/include/mbgl/style/conversion/geojson_options.hpp b/include/mbgl/style/conversion/geojson_options.hpp index 3f625babb6..89511848dd 100644 --- a/include/mbgl/style/conversion/geojson_options.hpp +++ b/include/mbgl/style/conversion/geojson_options.hpp @@ -1,7 +1,8 @@ #pragma once -#include <mbgl/style/conversion.hpp> #include <mbgl/style/sources/geojson_source.hpp> +#include <mbgl/style/conversion.hpp> +#include <mbgl/util/optional.hpp> namespace mbgl { namespace style { diff --git a/include/mbgl/style/conversion/layer.hpp b/include/mbgl/style/conversion/layer.hpp index 2df6c9e381..9cf019378b 100644 --- a/include/mbgl/style/conversion/layer.hpp +++ b/include/mbgl/style/conversion/layer.hpp @@ -2,6 +2,7 @@ #include <mbgl/style/layer.hpp> #include <mbgl/style/conversion.hpp> +#include <mbgl/util/optional.hpp> #include <memory> diff --git a/include/mbgl/style/conversion/light.hpp b/include/mbgl/style/conversion/light.hpp index 289fca2e31..2f6f8628b8 100644 --- a/include/mbgl/style/conversion/light.hpp +++ b/include/mbgl/style/conversion/light.hpp @@ -2,6 +2,7 @@ #include <mbgl/style/light.hpp> #include <mbgl/style/conversion.hpp> +#include <mbgl/util/optional.hpp> namespace mbgl { namespace style { diff --git a/include/mbgl/style/conversion/position.hpp b/include/mbgl/style/conversion/position.hpp index 044c45862d..10db5c6ec1 100644 --- a/include/mbgl/style/conversion/position.hpp +++ b/include/mbgl/style/conversion/position.hpp @@ -1,7 +1,8 @@ #pragma once -#include <mbgl/style/conversion.hpp> #include <mbgl/style/position.hpp> +#include <mbgl/style/conversion.hpp> +#include <mbgl/util/optional.hpp> namespace mbgl { namespace style { diff --git a/include/mbgl/style/conversion/property_value.hpp b/include/mbgl/style/conversion/property_value.hpp index fa6752867b..f6f36db983 100644 --- a/include/mbgl/style/conversion/property_value.hpp +++ b/include/mbgl/style/conversion/property_value.hpp @@ -1,9 +1,9 @@ #pragma once #include <mbgl/style/property_value.hpp> -#include <mbgl/style/conversion.hpp> #include <mbgl/style/conversion/constant.hpp> #include <mbgl/style/conversion/function.hpp> +#include <mbgl/style/conversion.hpp> #include <mbgl/style/expression/value.hpp> #include <mbgl/style/expression/is_constant.hpp> #include <mbgl/style/expression/is_expression.hpp> @@ -16,53 +16,7 @@ namespace conversion { template <class T> struct Converter<PropertyValue<T>> { - optional<PropertyValue<T>> operator()(const Convertible& value, Error& error, bool allowDataExpressions, bool convertTokens) const { - using namespace mbgl::style::expression; - - if (isUndefined(value)) { - return PropertyValue<T>(); - } - - optional<PropertyExpression<T>> expression; - - if (isExpression(value)) { - ParsingContext ctx(valueTypeToExpressionType<T>()); - ParseResult parsed = ctx.parseLayerPropertyExpression(value); - if (!parsed) { - error.message = ctx.getCombinedErrors(); - return nullopt; - } - expression = PropertyExpression<T>(std::move(*parsed)); - } else if (isObject(value)) { - expression = convertFunctionToExpression<T>(value, error, convertTokens); - } else { - optional<T> constant = convert<T>(value, error); - if (!constant) { - return nullopt; - } - return convertTokens ? maybeConvertTokens(*constant) : PropertyValue<T>(*constant); - } - - if (!expression) { - return nullopt; - } else if (!allowDataExpressions && !(*expression).isFeatureConstant()) { - error.message = "data expressions not supported"; - return nullopt; - } else if (!(*expression).isFeatureConstant() || !(*expression).isZoomConstant()) { - return { std::move(*expression) }; - } else if ((*expression).getExpression().getKind() == Kind::Literal) { - optional<T> constant = fromExpressionValue<T>( - static_cast<const Literal&>((*expression).getExpression()).getValue()); - if (!constant) { - return nullopt; - } - return PropertyValue<T>(*constant); - } else { - assert(false); - error.message = "expected a literal expression"; - return nullopt; - } - } + optional<PropertyValue<T>> operator()(const Convertible& value, Error& error, bool allowDataExpressions, bool convertTokens) const; template <class S> PropertyValue<T> maybeConvertTokens(const S& t) const { diff --git a/include/mbgl/style/conversion/source.hpp b/include/mbgl/style/conversion/source.hpp index 2cf2e36da4..19bc1ce6b6 100644 --- a/include/mbgl/style/conversion/source.hpp +++ b/include/mbgl/style/conversion/source.hpp @@ -1,7 +1,8 @@ #pragma once -#include <mbgl/style/conversion.hpp> #include <mbgl/style/source.hpp> +#include <mbgl/style/conversion.hpp> +#include <mbgl/util/optional.hpp> #include <memory> diff --git a/include/mbgl/style/conversion/tileset.hpp b/include/mbgl/style/conversion/tileset.hpp index 1fb4acf70d..88661c358c 100644 --- a/include/mbgl/style/conversion/tileset.hpp +++ b/include/mbgl/style/conversion/tileset.hpp @@ -2,6 +2,7 @@ #include <mbgl/util/tileset.hpp> #include <mbgl/style/conversion.hpp> +#include <mbgl/util/optional.hpp> namespace mbgl { namespace style { diff --git a/include/mbgl/style/conversion/transition_options.hpp b/include/mbgl/style/conversion/transition_options.hpp index 0563f39ac3..a72d757d3c 100644 --- a/include/mbgl/style/conversion/transition_options.hpp +++ b/include/mbgl/style/conversion/transition_options.hpp @@ -2,6 +2,7 @@ #include <mbgl/style/transition_options.hpp> #include <mbgl/style/conversion.hpp> +#include <mbgl/util/optional.hpp> namespace mbgl { namespace style { diff --git a/include/mbgl/style/conversion_impl.hpp b/include/mbgl/style/conversion_impl.hpp new file mode 100644 index 0000000000..27b2ee1917 --- /dev/null +++ b/include/mbgl/style/conversion_impl.hpp @@ -0,0 +1,302 @@ +#pragma once + +#include <mbgl/style/conversion.hpp> +#include <mbgl/util/optional.hpp> +#include <mbgl/util/feature.hpp> +#include <mbgl/util/geojson.hpp> + +#include <string> + +namespace mbgl { +namespace style { +namespace conversion { + +/* + The `conversion` namespace defines conversions from JSON structures conforming to the schema defined by + the Mapbox Style Specification, to the various C++ types that form the C++ model of that domain: + + * `std::unique_ptr<Source>` + * `std::unique_ptr<Layer>` + * `Filter` + * `PropertyValue<T>` + + A single template function serves as the public interface: + + template <class T> + optional<T> convert(const Convertible& input, Error& error); + + Where `T` is one of the above types. If the conversion fails, the result is empty, and the + error parameter includes diagnostic text suitable for presentation to a library user. Otherwise, + a filled optional is returned. + + `Convertible` is a type that encapsulates a special form of polymorphism over various underlying types that + can serve as input to the conversion algorithm. For instance, on macOS, we need to support + conversion from both RapidJSON types, and a JSON structure represented with `NSArray`/`NSDictionary`/etc. + On Qt, we need to support conversion from RapidJSON types and QVariant. + + We don't want to use traditional forms of polymorphism to accomplish this: + + * Compile time polymorphism using a template parameter for the actual value type leads to + excessive code bloat and long compile times. + * Runtime polymorphism using virtual methods requires extra heap allocation and ubiquitous + use of std::unique_ptr, unsuitable for this performance-sensitive code. + + Therefore, we're using a custom implementation of runtime polymorphism where we manually create and + dispatch through a table of function pointers (vtable), while keeping the storage for any of the possible + underlying types inline on the stack, using `std::aligned_storage`. + + For a given underlying type T, an explicit specialization of `ConversionTraits<T>` must be provided. This + specialization must provide the following static methods: + + * `isUndefined(v)` -- returns a boolean indication whether `v` is undefined or a JSON null + + * `isArray(v)` -- returns a boolean indicating whether `v` represents a JSON array + * `arrayLength(v)` -- called only if `isArray(v)`; returns a size_t length + * `arrayMember(v)` -- called only if `isArray(v)`; returns `V` or `V&` + + * `isObject(v)` -- returns a boolean indicating whether `v` represents a JSON object + * `objectMember(v, name)` -- called only if `isObject(v)`; `name` is `const char *`; return value: + * is true when evaluated in a boolean context iff the named member exists + * is convertable to a `V` or `V&` when dereferenced + * `eachMember(v, [] (const std::string&, const V&) -> optional<Error> {...})` -- called + only if `isObject(v)`; calls the provided lambda once for each key and value of the object; + short-circuits if any call returns an `Error` + + * `toBool(v)` -- returns `optional<bool>`, absence indicating `v` is not a JSON boolean + * `toNumber(v)` -- returns `optional<float>`, absence indicating `v` is not a JSON number + * `toDouble(v)` -- returns `optional<double>`, absence indicating `v` is not a JSON number + * `toString(v)` -- returns `optional<std::string>`, absence indicating `v` is not a JSON string + * `toValue(v)` -- returns `optional<Value>`, a variant type, for generic conversion, + absence indicating `v` is not a boolean, number, or string. Numbers should be converted to + unsigned integer, signed integer, or floating point, in descending preference. + + In addition, the type T must be move-constructable. And finally, `Convertible::Storage`, a typedef for + `std::aligned_storage_t`, must be large enough to satisfy the memory requirements for any of the + possible underlying types. (A static assert will fail if this is not the case.) + + `Convertible` itself is movable, but not copyable. A moved-from `Convertible` is in an invalid state; + you must not do anything with it except let it go out of scope. +*/ + +template <typename T> +class ConversionTraits; + +class Convertible { +public: + template <typename T> + Convertible(T&& value) : vtable(vtableForType<std::decay_t<T>>()) { + static_assert(sizeof(Storage) >= sizeof(std::decay_t<T>), "Storage must be large enough to hold value type"); + new (static_cast<void*>(&storage)) std::decay_t<T>(std::forward<T>(value)); + } + + Convertible(Convertible&& v) + : vtable(v.vtable) + { + if (vtable) { + vtable->move(std::move(v.storage), this->storage); + } + } + + ~Convertible() { + if (vtable) { + vtable->destroy(storage); + } + } + + Convertible& operator=(Convertible&& v) { + if (vtable) { + vtable->destroy(storage); + } + vtable = v.vtable; + if (vtable) { + vtable->move(std::move(v.storage), this->storage); + } + v.vtable = nullptr; + return *this; + } + + Convertible() = delete; + Convertible(const Convertible&) = delete; + Convertible& operator=(const Convertible&) = delete; + + friend inline bool isUndefined(const Convertible& v) { + assert(v.vtable); + return v.vtable->isUndefined(v.storage); + } + + friend inline bool isArray(const Convertible& v) { + assert(v.vtable); + return v.vtable->isArray(v.storage); + } + + friend inline std::size_t arrayLength(const Convertible& v) { + assert(v.vtable); + return v.vtable->arrayLength(v.storage); + } + + friend inline Convertible arrayMember(const Convertible& v, std::size_t i) { + assert(v.vtable); + return v.vtable->arrayMember(v.storage, i); + } + + friend inline bool isObject(const Convertible& v) { + assert(v.vtable); + return v.vtable->isObject(v.storage); + } + + friend inline optional<Convertible> objectMember(const Convertible& v, const char * name) { + assert(v.vtable); + return v.vtable->objectMember(v.storage, name); + } + + friend inline optional<Error> eachMember(const Convertible& v, const std::function<optional<Error> (const std::string&, const Convertible&)>& fn) { + assert(v.vtable); + return v.vtable->eachMember(v.storage, fn); + } + + friend inline optional<bool> toBool(const Convertible& v) { + assert(v.vtable); + return v.vtable->toBool(v.storage); + } + + friend inline optional<float> toNumber(const Convertible& v) { + assert(v.vtable); + return v.vtable->toNumber(v.storage); + } + + friend inline optional<double> toDouble(const Convertible& v) { + assert(v.vtable); + return v.vtable->toDouble(v.storage); + } + + friend inline optional<std::string> toString(const Convertible& v) { + assert(v.vtable); + return v.vtable->toString(v.storage); + } + + friend inline optional<Value> toValue(const Convertible& v) { + assert(v.vtable); + return v.vtable->toValue(v.storage); + } + + friend inline optional<GeoJSON> toGeoJSON(const Convertible& v, Error& error) { + assert(v.vtable); + return v.vtable->toGeoJSON(v.storage, error); + } + +private: +#if __ANDROID__ + // Android: JSValue* or mbgl::android::Value + using Storage = std::aligned_storage_t<32, 8>; +#elif __QT__ + // Qt: JSValue* or QVariant + using Storage = std::aligned_storage_t<32, 8>; +#else + // Node: JSValue* or v8::Local<v8::Value> + // iOS/macOS: JSValue* or id + using Storage = std::aligned_storage_t<8, 8>; +#endif + + struct VTable { + void (*move) (Storage&& src, Storage& dest); + void (*destroy) (Storage&); + + bool (*isUndefined) (const Storage&); + + bool (*isArray) (const Storage&); + std::size_t (*arrayLength) (const Storage&); + Convertible (*arrayMember) (const Storage&, std::size_t); + + bool (*isObject) (const Storage&); + optional<Convertible> (*objectMember) (const Storage&, const char *); + optional<Error> (*eachMember) (const Storage&, const std::function<optional<Error> (const std::string&, const Convertible&)>&); + + optional<bool> (*toBool) (const Storage&); + optional<float> (*toNumber) (const Storage&); + optional<double> (*toDouble) (const Storage&); + optional<std::string> (*toString) (const Storage&); + optional<Value> (*toValue) (const Storage&); + + // https://github.com/mapbox/mapbox-gl-native/issues/5623 + optional<GeoJSON> (*toGeoJSON) (const Storage&, Error&); + }; + + // Extracted this function from the table below to work around a GCC bug with differing + // visibility settings for capturing lambdas: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80947 + template <typename T> + static auto vtableEachMember(const Storage& s, const std::function<optional<Error>(const std::string&, const Convertible&)>& fn) { + return ConversionTraits<T>::eachMember(reinterpret_cast<const T&>(s), [&](const std::string& k, T&& v) { + return fn(k, Convertible(std::move(v))); + }); + } + + template <typename T> + static VTable* vtableForType() { + using Traits = ConversionTraits<T>; + static VTable vtable = { + [] (Storage&& src, Storage& dest) { + auto srcValue = reinterpret_cast<T&&>(src); + new (static_cast<void*>(&dest)) T(std::move(srcValue)); + srcValue.~T(); + }, + [] (Storage& s) { + reinterpret_cast<T&>(s).~T(); + }, + [] (const Storage& s) { + return Traits::isUndefined(reinterpret_cast<const T&>(s)); + }, + [] (const Storage& s) { + return Traits::isArray(reinterpret_cast<const T&>(s)); + }, + [] (const Storage& s) { + return Traits::arrayLength(reinterpret_cast<const T&>(s)); + }, + [] (const Storage& s, std::size_t i) { + return Convertible(Traits::arrayMember(reinterpret_cast<const T&>(s), i)); + }, + [] (const Storage& s) { + return Traits::isObject(reinterpret_cast<const T&>(s)); + }, + [] (const Storage& s, const char * key) { + optional<T> member = Traits::objectMember(reinterpret_cast<const T&>(s), key); + if (member) { + return optional<Convertible>(Convertible(std::move(*member))); + } else { + return optional<Convertible>(); + } + }, + vtableEachMember<T>, + [] (const Storage& s) { + return Traits::toBool(reinterpret_cast<const T&>(s)); + }, + [] (const Storage& s) { + return Traits::toNumber(reinterpret_cast<const T&>(s)); + }, + [] (const Storage& s) { + return Traits::toDouble(reinterpret_cast<const T&>(s)); + }, + [] (const Storage& s) { + return Traits::toString(reinterpret_cast<const T&>(s)); + }, + [] (const Storage& s) { + return Traits::toValue(reinterpret_cast<const T&>(s)); + }, + [] (const Storage& s, Error& err) { + return Traits::toGeoJSON(reinterpret_cast<const T&>(s), err); + } + }; + return &vtable; + } + + VTable* vtable; + Storage storage; +}; + +template <class T, class...Args> +optional<T> convert(const Convertible& value, Error& error, Args&&...args) { + return Converter<T>()(value, error, std::forward<Args>(args)...); +} + +} // namespace conversion +} // namespace style +} // namespace mbgl diff --git a/include/mbgl/style/expression/assertion.hpp b/include/mbgl/style/expression/assertion.hpp index 90da16b068..239cdf2ea6 100644 --- a/include/mbgl/style/expression/assertion.hpp +++ b/include/mbgl/style/expression/assertion.hpp @@ -1,8 +1,8 @@ #pragma once #include <mbgl/style/expression/expression.hpp> -#include <mbgl/style/conversion.hpp> #include <mbgl/style/expression/parsing_context.hpp> +#include <mbgl/style/conversion.hpp> #include <memory> #include <vector> diff --git a/include/mbgl/style/expression/case.hpp b/include/mbgl/style/expression/case.hpp index 02dc3bc4c2..7cd007d3c7 100644 --- a/include/mbgl/style/expression/case.hpp +++ b/include/mbgl/style/expression/case.hpp @@ -1,8 +1,8 @@ #pragma once #include <mbgl/style/expression/expression.hpp> -#include <mbgl/style/conversion.hpp> #include <mbgl/style/expression/parsing_context.hpp> +#include <mbgl/style/conversion.hpp> #include <memory> #include <vector> diff --git a/include/mbgl/style/expression/coalesce.hpp b/include/mbgl/style/expression/coalesce.hpp index cd60cee02e..c4216f234f 100644 --- a/include/mbgl/style/expression/coalesce.hpp +++ b/include/mbgl/style/expression/coalesce.hpp @@ -1,8 +1,8 @@ #pragma once #include <mbgl/style/expression/expression.hpp> -#include <mbgl/style/conversion.hpp> #include <mbgl/style/expression/parsing_context.hpp> +#include <mbgl/style/conversion.hpp> #include <memory> #include <map> diff --git a/include/mbgl/style/expression/compound_expression.hpp b/include/mbgl/style/expression/compound_expression.hpp index ef10dadb55..b54720a258 100644 --- a/include/mbgl/style/expression/compound_expression.hpp +++ b/include/mbgl/style/expression/compound_expression.hpp @@ -1,10 +1,10 @@ #pragma once #include <mbgl/style/expression/expression.hpp> -#include <mbgl/style/conversion.hpp> #include <mbgl/style/expression/parsing_context.hpp> #include <mbgl/style/expression/type.hpp> #include <mbgl/style/expression/value.hpp> +#include <mbgl/style/conversion.hpp> #include <mbgl/util/optional.hpp> #include <memory> diff --git a/include/mbgl/style/expression/parsing_context.hpp b/include/mbgl/style/expression/parsing_context.hpp index c19974a4f7..66014e33d4 100644 --- a/include/mbgl/style/expression/parsing_context.hpp +++ b/include/mbgl/style/expression/parsing_context.hpp @@ -7,6 +7,7 @@ #include <iterator> #include <map> +#include <unordered_map> #include <string> #include <vector> #include <memory> diff --git a/include/mbgl/style/layer.hpp b/include/mbgl/style/layer.hpp index e0f71d2689..3b7969ea79 100644 --- a/include/mbgl/style/layer.hpp +++ b/include/mbgl/style/layer.hpp @@ -3,6 +3,7 @@ #include <mbgl/util/noncopyable.hpp> #include <mbgl/util/peer.hpp> #include <mbgl/util/immutable.hpp> +#include <mbgl/util/optional.hpp> #include <mbgl/style/layer_type.hpp> #include <mbgl/style/types.hpp> #include <mbgl/style/conversion.hpp> |