2 * Copyright 2016 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
20 #include <boost/iterator/iterator_adaptor.hpp>
21 #include <boost/iterator/iterator_facade.hpp>
22 #include <folly/Likely.h>
23 #include <folly/Conv.h>
24 #include <folly/Format.h>
26 //////////////////////////////////////////////////////////////////////
31 struct hash< ::folly::dynamic> {
32 size_t operator()(::folly::dynamic const& d) const {
39 //////////////////////////////////////////////////////////////////////
41 // This is a higher-order preprocessor macro to aid going from runtime
42 // types to the compile time type system.
43 #define FB_DYNAMIC_APPLY(type, apply) \
73 //////////////////////////////////////////////////////////////////////
77 struct TypeError : std::runtime_error {
78 explicit TypeError(const std::string& expected, dynamic::Type actual);
79 explicit TypeError(const std::string& expected,
80 dynamic::Type actual1, dynamic::Type actual2);
85 //////////////////////////////////////////////////////////////////////
89 // This helper is used in destroy() to be able to run destructors on
90 // types like "int64_t" without a compiler error.
92 template<class T> static void destroy(T* t) { t->~T(); }
96 * The enable_if junk here is necessary to avoid ambiguous
97 * conversions relating to bool and double when you implicitly
98 * convert an int or long to a dynamic.
100 template<class T, class Enable = void> struct ConversionHelper;
102 struct ConversionHelper<
104 typename std::enable_if<
105 std::is_integral<T>::value && !std::is_same<T,bool>::value
108 typedef int64_t type;
111 struct ConversionHelper<float> {
115 struct ConversionHelper<
117 typename std::enable_if<
118 (!std::is_integral<T>::value || std::is_same<T, bool>::value) &&
119 !std::is_same<T, float>::value &&
120 !std::is_same<T, std::nullptr_t>::value>::type> {
124 struct ConversionHelper<
126 typename std::enable_if<
127 std::is_same<T,std::nullptr_t>::value
134 * Helper for implementing numeric conversions in operators on
135 * numbers. Just promotes to double when one of the arguments is
136 * double, or throws if either is not a numeric type.
138 template<template<class> class Op>
139 dynamic numericOp(dynamic const& a, dynamic const& b) {
140 if (!a.isNumber() || !b.isNumber()) {
141 throw TypeError("numeric", a.type(), b.type());
143 if (a.type() != b.type()) {
144 auto& integ = a.isInt() ? a : b;
145 auto& nonint = a.isInt() ? b : a;
146 return Op<double>()(to<double>(integ.asInt()), nonint.asDouble());
149 return Op<double>()(a.asDouble(), b.asDouble());
151 return Op<int64_t>()(a.asInt(), b.asInt());
156 //////////////////////////////////////////////////////////////////////
159 * We're doing this instead of a simple member typedef to avoid the
160 * undefined behavior of parameterizing std::unordered_map<> with an
163 * Note: Later we may add separate order tracking here (a multi-index
166 struct dynamic::ObjectImpl : std::unordered_map<dynamic, dynamic> {};
168 //////////////////////////////////////////////////////////////////////
170 // Helper object for creating objects conveniently. See object and
171 // the dynamic::dynamic(ObjectMaker&&) ctor.
172 struct dynamic::ObjectMaker {
173 friend struct dynamic;
175 explicit ObjectMaker() : val_(dynamic::object) {}
176 explicit ObjectMaker(dynamic const& key, dynamic val)
177 : val_(dynamic::object)
179 val_.insert(key, std::move(val));
181 explicit ObjectMaker(dynamic&& key, dynamic val)
182 : val_(dynamic::object)
184 val_.insert(std::move(key), std::move(val));
187 // Make sure no one tries to save one of these into an lvalue with
188 // auto or anything like that.
189 ObjectMaker(ObjectMaker&&) = default;
190 ObjectMaker(ObjectMaker const&) = delete;
191 ObjectMaker& operator=(ObjectMaker const&) = delete;
192 ObjectMaker& operator=(ObjectMaker&&) = delete;
194 // These return rvalue-references instead of lvalue-references to allow
195 // constructs like this to moved instead of copied:
196 // dynamic a = dynamic::object("a", "b")("c", "d")
197 ObjectMaker&& operator()(dynamic const& key, dynamic val) {
198 val_.insert(key, std::move(val));
199 return std::move(*this);
202 ObjectMaker&& operator()(dynamic&& key, dynamic val) {
203 val_.insert(std::move(key), std::move(val));
204 return std::move(*this);
211 inline void dynamic::array(EmptyArrayTag) {}
213 template <class... Args>
214 inline dynamic dynamic::array(Args&& ...args) {
215 return dynamic(Array{std::forward<Args>(args)...});
218 // This looks like a case for perfect forwarding, but our use of
219 // std::initializer_list for constructing dynamic arrays makes it less
220 // functional than doing this manually.
222 // TODO(ott, 10300209): When the initializer_list constructor is gone,
224 inline dynamic::ObjectMaker dynamic::object() { return ObjectMaker(); }
225 inline dynamic::ObjectMaker dynamic::object(dynamic&& a, dynamic&& b) {
226 return ObjectMaker(std::move(a), std::move(b));
228 inline dynamic::ObjectMaker dynamic::object(dynamic const& a, dynamic&& b) {
229 return ObjectMaker(a, std::move(b));
231 inline dynamic::ObjectMaker dynamic::object(dynamic&& a, dynamic const& b) {
232 return ObjectMaker(std::move(a), b);
234 inline dynamic::ObjectMaker
235 dynamic::object(dynamic const& a, dynamic const& b) {
236 return ObjectMaker(a, b);
239 //////////////////////////////////////////////////////////////////////
241 struct dynamic::const_item_iterator
242 : boost::iterator_adaptor<dynamic::const_item_iterator,
243 dynamic::ObjectImpl::const_iterator> {
244 /* implicit */ const_item_iterator(base_type b) : iterator_adaptor_(b) { }
247 friend class boost::iterator_core_access;
250 struct dynamic::const_key_iterator
251 : boost::iterator_adaptor<dynamic::const_key_iterator,
252 dynamic::ObjectImpl::const_iterator,
254 /* implicit */ const_key_iterator(base_type b) : iterator_adaptor_(b) { }
257 dynamic const& dereference() const {
258 return base_reference()->first;
260 friend class boost::iterator_core_access;
263 struct dynamic::const_value_iterator
264 : boost::iterator_adaptor<dynamic::const_value_iterator,
265 dynamic::ObjectImpl::const_iterator,
267 /* implicit */ const_value_iterator(base_type b) : iterator_adaptor_(b) { }
270 dynamic const& dereference() const {
271 return base_reference()->second;
273 friend class boost::iterator_core_access;
276 //////////////////////////////////////////////////////////////////////
278 inline dynamic::dynamic(void (*)(EmptyArrayTag))
281 new (&u_.array) Array();
284 inline dynamic::dynamic(ObjectMaker (*)())
287 new (getAddress<ObjectImpl>()) ObjectImpl();
290 inline dynamic::dynamic(StringPiece s)
293 new (&u_.string) std::string(s.data(), s.size());
296 inline dynamic::dynamic(char const* s)
299 new (&u_.string) std::string(s);
302 inline dynamic::dynamic(std::string const& s)
305 new (&u_.string) std::string(s);
308 inline dynamic::dynamic(std::string&& s) : type_(STRING) {
309 new (&u_.string) std::string(std::move(s));
312 inline dynamic::dynamic(ObjectMaker&& maker)
315 new (getAddress<ObjectImpl>())
316 ObjectImpl(std::move(*maker.val_.getAddress<ObjectImpl>()));
319 inline dynamic::dynamic(dynamic const& o)
325 inline dynamic::dynamic(dynamic&& o) noexcept
328 *this = std::move(o);
331 inline dynamic::~dynamic() noexcept { destroy(); }
334 dynamic::dynamic(T t) {
335 typedef typename detail::ConversionHelper<T>::type U;
336 type_ = TypeInfo<U>::type;
337 new (getAddress<U>()) U(std::move(t));
340 template<class Iterator>
341 dynamic::dynamic(Iterator first, Iterator last)
344 new (&u_.array) Array(first, last);
347 //////////////////////////////////////////////////////////////////////
349 inline dynamic::const_iterator dynamic::begin() const {
350 return get<Array>().begin();
352 inline dynamic::const_iterator dynamic::end() const {
353 return get<Array>().end();
357 struct dynamic::IterableProxy {
358 typedef It const_iterator;
359 typedef typename It::value_type value_type;
361 /* implicit */ IterableProxy(const dynamic::ObjectImpl* o) : o_(o) { }
372 const dynamic::ObjectImpl* o_;
375 inline dynamic::IterableProxy<dynamic::const_key_iterator> dynamic::keys()
377 return &(get<ObjectImpl>());
380 inline dynamic::IterableProxy<dynamic::const_value_iterator> dynamic::values()
382 return &(get<ObjectImpl>());
385 inline dynamic::IterableProxy<dynamic::const_item_iterator> dynamic::items()
387 return &(get<ObjectImpl>());
390 inline bool dynamic::isString() const {
391 return get_nothrow<std::string>();
393 inline bool dynamic::isObject() const { return get_nothrow<ObjectImpl>(); }
394 inline bool dynamic::isBool() const { return get_nothrow<bool>(); }
395 inline bool dynamic::isArray() const { return get_nothrow<Array>(); }
396 inline bool dynamic::isDouble() const { return get_nothrow<double>(); }
397 inline bool dynamic::isInt() const { return get_nothrow<int64_t>(); }
398 inline bool dynamic::isNull() const { return get_nothrow<void*>(); }
399 inline bool dynamic::isNumber() const { return isInt() || isDouble(); }
401 inline dynamic::Type dynamic::type() const {
405 inline std::string dynamic::asString() const {
406 return asImpl<std::string>();
408 inline double dynamic::asDouble() const {
409 return asImpl<double>();
411 inline int64_t dynamic::asInt() const {
412 return asImpl<int64_t>();
414 inline bool dynamic::asBool() const {
415 return asImpl<bool>();
418 inline const std::string& dynamic::getString() const& {
419 return get<std::string>();
421 inline double dynamic::getDouble() const& { return get<double>(); }
422 inline int64_t dynamic::getInt() const& { return get<int64_t>(); }
423 inline bool dynamic::getBool() const& { return get<bool>(); }
425 inline std::string& dynamic::getString()& {
426 return get<std::string>();
428 inline double& dynamic::getDouble() & { return get<double>(); }
429 inline int64_t& dynamic::getInt() & { return get<int64_t>(); }
430 inline bool& dynamic::getBool() & { return get<bool>(); }
432 inline std::string&& dynamic::getString()&& {
433 return std::move(get<std::string>());
435 inline double dynamic::getDouble() && { return get<double>(); }
436 inline int64_t dynamic::getInt() && { return get<int64_t>(); }
437 inline bool dynamic::getBool() && { return get<bool>(); }
439 inline const char* dynamic::data() const& {
440 return get<std::string>().data();
442 inline const char* dynamic::c_str() const& {
443 return get<std::string>().c_str();
445 inline StringPiece dynamic::stringPiece() const {
446 return get<std::string>();
450 struct dynamic::CompareOp {
451 static bool comp(T const& a, T const& b) { return a < b; }
454 struct dynamic::CompareOp<dynamic::ObjectImpl> {
455 static bool comp(ObjectImpl const&, ObjectImpl const&) {
456 // This code never executes; it is just here for the compiler.
461 inline dynamic& dynamic::operator+=(dynamic const& o) {
462 if (type() == STRING && o.type() == STRING) {
463 *getAddress<std::string>() += *o.getAddress<std::string>();
466 *this = detail::numericOp<std::plus>(*this, o);
470 inline dynamic& dynamic::operator-=(dynamic const& o) {
471 *this = detail::numericOp<std::minus>(*this, o);
475 inline dynamic& dynamic::operator*=(dynamic const& o) {
476 *this = detail::numericOp<std::multiplies>(*this, o);
480 inline dynamic& dynamic::operator/=(dynamic const& o) {
481 *this = detail::numericOp<std::divides>(*this, o);
485 #define FB_DYNAMIC_INTEGER_OP(op) \
486 inline dynamic& dynamic::operator op(dynamic const& o) { \
487 if (!isInt() || !o.isInt()) { \
488 throw TypeError("int64", type(), o.type()); \
490 *getAddress<int64_t>() op o.asInt(); \
494 FB_DYNAMIC_INTEGER_OP(%=)
495 FB_DYNAMIC_INTEGER_OP(|=)
496 FB_DYNAMIC_INTEGER_OP(&=)
497 FB_DYNAMIC_INTEGER_OP(^=)
499 #undef FB_DYNAMIC_INTEGER_OP
501 inline dynamic& dynamic::operator++() {
506 inline dynamic& dynamic::operator--() {
511 inline dynamic const& dynamic::operator[](dynamic const& idx) const& {
515 inline dynamic&& dynamic::operator[](dynamic const& idx) && {
516 return std::move((*this)[idx]);
519 template<class K, class V> inline dynamic& dynamic::setDefault(K&& k, V&& v) {
520 auto& obj = get<ObjectImpl>();
521 return obj.insert(std::make_pair(std::forward<K>(k),
522 std::forward<V>(v))).first->second;
525 template<class K> inline dynamic& dynamic::setDefault(K&& k, dynamic&& v) {
526 auto& obj = get<ObjectImpl>();
527 return obj.insert(std::make_pair(std::forward<K>(k),
528 std::move(v))).first->second;
531 template<class K> inline dynamic& dynamic::setDefault(K&& k, const dynamic& v) {
532 auto& obj = get<ObjectImpl>();
533 return obj.insert(std::make_pair(std::forward<K>(k), v)).first->second;
536 inline dynamic* dynamic::get_ptr(dynamic const& idx) & {
537 return const_cast<dynamic*>(const_cast<dynamic const*>(this)->get_ptr(idx));
540 inline dynamic& dynamic::at(dynamic const& idx) & {
541 return const_cast<dynamic&>(const_cast<dynamic const*>(this)->at(idx));
544 inline dynamic&& dynamic::at(dynamic const& idx) && {
545 return std::move(at(idx));
548 inline bool dynamic::empty() const {
555 inline std::size_t dynamic::count(dynamic const& key) const {
556 return find(key) != items().end();
559 inline dynamic::const_item_iterator dynamic::find(dynamic const& key) const {
560 return get<ObjectImpl>().find(key);
563 template<class K, class V> inline void dynamic::insert(K&& key, V&& val) {
564 auto& obj = get<ObjectImpl>();
565 auto rv = obj.insert({ std::forward<K>(key), nullptr });
566 rv.first->second = std::forward<V>(val);
569 inline void dynamic::update(const dynamic& mergeObj) {
570 if (!isObject() || !mergeObj.isObject()) {
571 throw TypeError("object", type(), mergeObj.type());
574 for (const auto& pair : mergeObj.items()) {
575 (*this)[pair.first] = pair.second;
579 inline void dynamic::update_missing(const dynamic& mergeObj1) {
580 if (!isObject() || !mergeObj1.isObject()) {
581 throw TypeError("object", type(), mergeObj1.type());
584 // Only add if not already there
585 for (const auto& pair : mergeObj1.items()) {
586 if ((*this).find(pair.first) == (*this).items().end()) {
587 (*this)[pair.first] = pair.second;
592 inline dynamic dynamic::merge(
593 const dynamic& mergeObj1,
594 const dynamic& mergeObj2) {
596 // No checks on type needed here because they are done in update_missing
597 // Note that we do update_missing here instead of update() because
598 // it will prevent the extra writes that would occur with update()
599 auto ret = mergeObj2;
600 ret.update_missing(mergeObj1);
604 inline std::size_t dynamic::erase(dynamic const& key) {
605 auto& obj = get<ObjectImpl>();
606 return obj.erase(key);
609 inline dynamic::const_iterator dynamic::erase(const_iterator it) {
610 auto& arr = get<Array>();
611 // std::vector doesn't have an erase method that works on const iterators,
612 // even though the standard says it should, so this hack converts to a
613 // non-const iterator before calling erase.
614 return get<Array>().erase(arr.begin() + (it - arr.begin()));
617 inline dynamic::const_key_iterator dynamic::erase(const_key_iterator it) {
618 return const_key_iterator(get<ObjectImpl>().erase(it.base()));
621 inline dynamic::const_key_iterator dynamic::erase(const_key_iterator first,
622 const_key_iterator last) {
623 return const_key_iterator(get<ObjectImpl>().erase(first.base(),
627 inline dynamic::const_value_iterator dynamic::erase(const_value_iterator it) {
628 return const_value_iterator(get<ObjectImpl>().erase(it.base()));
631 inline dynamic::const_value_iterator dynamic::erase(const_value_iterator first,
632 const_value_iterator last) {
633 return const_value_iterator(get<ObjectImpl>().erase(first.base(),
637 inline dynamic::const_item_iterator dynamic::erase(const_item_iterator it) {
638 return const_item_iterator(get<ObjectImpl>().erase(it.base()));
641 inline dynamic::const_item_iterator dynamic::erase(const_item_iterator first,
642 const_item_iterator last) {
643 return const_item_iterator(get<ObjectImpl>().erase(first.base(),
647 inline void dynamic::resize(std::size_t sz, dynamic const& c) {
648 auto& arr = get<Array>();
652 inline void dynamic::push_back(dynamic const& v) {
653 auto& arr = get<Array>();
657 inline void dynamic::push_back(dynamic&& v) {
658 auto& arr = get<Array>();
659 arr.push_back(std::move(v));
662 inline void dynamic::pop_back() {
663 auto& arr = get<Array>();
667 //////////////////////////////////////////////////////////////////////
669 inline dynamic::dynamic(Array&& r) : type_(ARRAY) {
670 new (&u_.array) Array(std::move(r));
673 #define FOLLY_DYNAMIC_DEC_TYPEINFO(T, str, val) \
674 template <> struct dynamic::TypeInfo<T> { \
675 static constexpr const char* name = str; \
676 static constexpr dynamic::Type type = val; \
680 FOLLY_DYNAMIC_DEC_TYPEINFO(void*, "null", dynamic::NULLT)
681 FOLLY_DYNAMIC_DEC_TYPEINFO(bool, "boolean", dynamic::BOOL)
682 FOLLY_DYNAMIC_DEC_TYPEINFO(std::string, "string", dynamic::STRING)
683 FOLLY_DYNAMIC_DEC_TYPEINFO(dynamic::Array, "array", dynamic::ARRAY)
684 FOLLY_DYNAMIC_DEC_TYPEINFO(double, "double", dynamic::DOUBLE)
685 FOLLY_DYNAMIC_DEC_TYPEINFO(int64_t, "int64", dynamic::INT64)
686 FOLLY_DYNAMIC_DEC_TYPEINFO(dynamic::ObjectImpl, "object", dynamic::OBJECT)
688 #undef FOLLY_DYNAMIC_DEC_TYPEINFO
691 T dynamic::asImpl() const {
693 case INT64: return to<T>(*get_nothrow<int64_t>());
694 case DOUBLE: return to<T>(*get_nothrow<double>());
695 case BOOL: return to<T>(*get_nothrow<bool>());
697 return to<T>(*get_nothrow<std::string>());
699 throw TypeError("int/double/bool/string", type());
703 // Return a T* to our type, or null if we're not that type.
705 T* dynamic::get_nothrow() & noexcept {
706 if (type_ != TypeInfo<T>::type) {
709 return getAddress<T>();
713 T const* dynamic::get_nothrow() const& noexcept {
714 return const_cast<dynamic*>(this)->get_nothrow<T>();
717 // Return T* for where we can put a T, without type checking. (Memory
718 // might be uninitialized, even.)
720 T* dynamic::getAddress() noexcept {
721 return GetAddrImpl<T>::get(u_);
725 T const* dynamic::getAddress() const noexcept {
726 return const_cast<dynamic*>(this)->getAddress<T>();
729 template<class T> struct dynamic::GetAddrImpl {};
730 template<> struct dynamic::GetAddrImpl<void*> {
731 static void** get(Data& d) noexcept { return &d.nul; }
733 template<> struct dynamic::GetAddrImpl<dynamic::Array> {
734 static Array* get(Data& d) noexcept { return &d.array; }
736 template<> struct dynamic::GetAddrImpl<bool> {
737 static bool* get(Data& d) noexcept { return &d.boolean; }
739 template<> struct dynamic::GetAddrImpl<int64_t> {
740 static int64_t* get(Data& d) noexcept { return &d.integer; }
742 template<> struct dynamic::GetAddrImpl<double> {
743 static double* get(Data& d) noexcept { return &d.doubl; }
746 struct dynamic::GetAddrImpl<std::string> {
747 static std::string* get(Data& d) noexcept {
751 template<> struct dynamic::GetAddrImpl<dynamic::ObjectImpl> {
752 static_assert(sizeof(ObjectImpl) <= sizeof(Data::objectBuffer),
753 "In your implementation, std::unordered_map<> apparently takes different"
754 " amount of space depending on its template parameters. This is "
755 "weird. Make objectBuffer bigger if you want to compile dynamic.");
757 static ObjectImpl* get(Data& d) noexcept {
758 void* data = &d.objectBuffer;
759 return static_cast<ObjectImpl*>(data);
765 if (auto* p = get_nothrow<T>()) {
768 throw TypeError(TypeInfo<T>::name, type());
772 T const& dynamic::get() const {
773 return const_cast<dynamic*>(this)->get<T>();
776 //////////////////////////////////////////////////////////////////////
779 * Helper for implementing operator<<. Throws if the type shouldn't
783 struct dynamic::PrintImpl {
784 static void print(dynamic const&, std::ostream& out, T const& t) {
788 // Otherwise, null, being (void*)0, would print as 0.
790 struct dynamic::PrintImpl<void*> {
791 static void print(dynamic const& /* d */,
794 DCHECK_EQ((void*)0, nul);
799 struct dynamic::PrintImpl<dynamic::ObjectImpl> {
800 static void print(dynamic const& d,
802 dynamic::ObjectImpl const&) {
803 d.print_as_pseudo_json(out);
807 struct dynamic::PrintImpl<dynamic::Array> {
808 static void print(dynamic const& d,
810 dynamic::Array const&) {
811 d.print_as_pseudo_json(out);
815 inline void dynamic::print(std::ostream& out) const {
816 #define FB_X(T) PrintImpl<T>::print(*this, out, *getAddress<T>())
817 FB_DYNAMIC_APPLY(type_, FB_X);
821 inline std::ostream& operator<<(std::ostream& out, dynamic const& d) {
826 //////////////////////////////////////////////////////////////////////
828 // Secialization of FormatValue so dynamic objects can be formatted
830 class FormatValue<dynamic> {
832 explicit FormatValue(const dynamic& val) : val_(val) { }
834 template <class FormatCallback>
835 void format(FormatArg& arg, FormatCallback& cb) const {
836 switch (val_.type()) {
838 FormatValue<std::nullptr_t>(nullptr).format(arg, cb);
841 FormatValue<bool>(val_.asBool()).format(arg, cb);
844 FormatValue<int64_t>(val_.asInt()).format(arg, cb);
846 case dynamic::STRING:
847 FormatValue<std::string>(val_.asString()).format(arg, cb);
849 case dynamic::DOUBLE:
850 FormatValue<double>(val_.asDouble()).format(arg, cb);
853 FormatValue(val_.at(arg.splitIntKey())).format(arg, cb);
855 case dynamic::OBJECT:
856 FormatValue(val_.at(arg.splitKey().toString())).format(arg, cb);
866 class FormatValue<detail::DefaultValueWrapper<dynamic, V>> {
868 explicit FormatValue(
869 const detail::DefaultValueWrapper<dynamic, V>& val)
872 template <class FormatCallback>
873 void format(FormatArg& arg, FormatCallback& cb) const {
874 auto& c = val_.container;
879 case dynamic::STRING:
880 case dynamic::DOUBLE:
881 FormatValue<dynamic>(c).format(arg, cb);
885 int key = arg.splitIntKey();
886 if (key >= 0 && size_t(key) < c.size()) {
887 FormatValue<dynamic>(c.at(key)).format(arg, cb);
889 FormatValue<V>(val_.defaultValue).format(arg, cb);
893 case dynamic::OBJECT:
895 auto pos = c.find(arg.splitKey());
896 if (pos != c.items().end()) {
897 FormatValue<dynamic>(pos->second).format(arg, cb);
899 FormatValue<V>(val_.defaultValue).format(arg, cb);
907 const detail::DefaultValueWrapper<dynamic, V>& val_;
912 #undef FB_DYNAMIC_APPLY