X-Git-Url: http://plrg.eecs.uci.edu/git/?p=folly.git;a=blobdiff_plain;f=folly%2Fdynamic-inl.h;h=7b187d7c88509df00f6fafc1bcc459c58fa982fd;hp=1942452c5feb627366b4aa9fcfd531ea424f97c4;hb=f885995c00a27e0e440c0e5cb66ec3298fc507d4;hpb=b9836f4a8dc28c2641f027cf47c6604b7268e37f

diff --git a/folly/dynamic-inl.h b/folly/dynamic-inl.h
index 1942452c..7b187d7c 100644
--- a/folly/dynamic-inl.h
+++ b/folly/dynamic-inl.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,134 +14,122 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DYNAMIC_INL_H_
-#define FOLLY_DYNAMIC_INL_H_
+#pragma once
 
 #include <functional>
+
 #include <boost/iterator/iterator_adaptor.hpp>
 #include <boost/iterator/iterator_facade.hpp>
-#include "folly/Likely.h"
-#include "folly/Conv.h"
-#include "folly/Format.h"
+
+#include <folly/Conv.h>
+#include <folly/Format.h>
+#include <folly/Likely.h>
 
 //////////////////////////////////////////////////////////////////////
 
 namespace std {
 
-template<>
-struct hash< ::folly::dynamic> {
+template <>
+struct hash<::folly::dynamic> {
   size_t operator()(::folly::dynamic const& d) const {
     return d.hash();
   }
 };
 
-}
+} // namespace std
 
 //////////////////////////////////////////////////////////////////////
 
 // This is a higher-order preprocessor macro to aid going from runtime
 // types to the compile time type system.
-#define FB_DYNAMIC_APPLY(type, apply) do {         \
-  switch ((type)) {                             \
-  case NULLT:   apply(void*);          break;   \
-  case ARRAY:   apply(Array);          break;   \
-  case BOOL:    apply(bool);           break;   \
-  case DOUBLE:  apply(double);         break;   \
-  case INT64:   apply(int64_t);        break;   \
-  case OBJECT:  apply(ObjectImpl);     break;   \
-  case STRING:  apply(fbstring);       break;   \
-  default:      CHECK(0); abort();              \
-  }                                             \
-} while (0)
+#define FB_DYNAMIC_APPLY(type, apply) \
+  do {                                \
+    switch ((type)) {                 \
+      case NULLT:                     \
+        apply(std::nullptr_t);        \
+        break;                        \
+      case ARRAY:                     \
+        apply(Array);                 \
+        break;                        \
+      case BOOL:                      \
+        apply(bool);                  \
+        break;                        \
+      case DOUBLE:                    \
+        apply(double);                \
+        break;                        \
+      case INT64:                     \
+        apply(int64_t);               \
+        break;                        \
+      case OBJECT:                    \
+        apply(ObjectImpl);            \
+        break;                        \
+      case STRING:                    \
+        apply(std::string);           \
+        break;                        \
+      default:                        \
+        CHECK(0);                     \
+        abort();                      \
+    }                                 \
+  } while (0)
 
 //////////////////////////////////////////////////////////////////////
 
 namespace folly {
 
+struct TypeError : std::runtime_error {
+  explicit TypeError(const std::string& expected, dynamic::Type actual);
+  explicit TypeError(
+      const std::string& expected,
+      dynamic::Type actual1,
+      dynamic::Type actual2);
+  ~TypeError() override;
+};
+
+[[noreturn]] void throwTypeError_(
+    std::string const& expected,
+    dynamic::Type actual);
+[[noreturn]] void throwTypeError_(
+    std::string const& expected,
+    dynamic::Type actual1,
+    dynamic::Type actual2);
+
 //////////////////////////////////////////////////////////////////////
 
 namespace detail {
 
-  // This helper is used in destroy() to be able to run destructors on
-  // types like "int64_t" without a compiler error.
-  struct Destroy {
-    template<class T> static void destroy(T* t) { t->~T(); }
-  };
-
-  /*
-   * The enable_if junk here is necessary to avoid ambiguous
-   * conversions relating to bool and double when you implicitly
-   * convert an int or long to a dynamic.
-   */
-  template<class T, class Enable = void> struct ConversionHelper;
-  template<class T>
-  struct ConversionHelper<
-    T,
-    typename std::enable_if<
-      std::is_integral<T>::value && !std::is_same<T,bool>::value
-    >::type
-  > {
-    typedef int64_t type;
-  };
-  template<class T>
-  struct ConversionHelper<
-    T,
-    typename std::enable_if<
-      (!std::is_integral<T>::value || std::is_same<T,bool>::value) &&
-      !std::is_same<T,std::nullptr_t>::value
-    >::type
-  > {
-    typedef T type;
-  };
-  template<class T>
-  struct ConversionHelper<
-    T,
-    typename std::enable_if<
-      std::is_same<T,std::nullptr_t>::value
-    >::type
-  > {
-    typedef void* type;
-  };
-
-  /*
-   * Helper for implementing numeric conversions in operators on
-   * numbers.  Just promotes to double when one of the arguments is
-   * double, or throws if either is not a numeric type.
-   */
-  template<template<class> class Op>
-  dynamic numericOp(dynamic const& a, dynamic const& b) {
-    if (!a.isNumber() || !b.isNumber()) {
-      throw TypeError("numeric", a.type(), b.type());
-    }
-    if (a.type() != b.type()) {
-      auto& integ  = a.isInt() ? a : b;
-      auto& nonint = a.isInt() ? b : a;
-      return Op<double>()(to<double>(integ.asInt()), nonint.asDouble());
-    }
-    if (a.isDouble()) {
-      return Op<double>()(a.asDouble(), b.asDouble());
-    }
-    return Op<int64_t>()(a.asInt(), b.asInt());
+// This helper is used in destroy() to be able to run destructors on
+// types like "int64_t" without a compiler error.
+struct Destroy {
+  template <class T>
+  static void destroy(T* t) {
+    t->~T();
   }
+};
 
+/*
+ * Helper for implementing numeric conversions in operators on
+ * numbers.  Just promotes to double when one of the arguments is
+ * double, or throws if either is not a numeric type.
+ */
+template <template <class> class Op>
+dynamic numericOp(dynamic const& a, dynamic const& b) {
+  if (!a.isNumber() || !b.isNumber()) {
+    throwTypeError_("numeric", a.type(), b.type());
+  }
+  if (a.type() != b.type()) {
+    auto& integ = a.isInt() ? a : b;
+    auto& nonint = a.isInt() ? b : a;
+    return Op<double>()(to<double>(integ.asInt()), nonint.asDouble());
+  }
+  if (a.isDouble()) {
+    return Op<double>()(a.asDouble(), b.asDouble());
+  }
+  return Op<int64_t>()(a.asInt(), b.asInt());
 }
 
-//////////////////////////////////////////////////////////////////////
+} // namespace detail
 
-struct TypeError : std::runtime_error {
-  explicit TypeError(const std::string& expected, dynamic::Type actual)
-    : std::runtime_error(to<std::string>("TypeError: expected dynamic "
-        "type `", expected, '\'', ", but had type `",
-        dynamic::typeName(actual), '\''))
-  {}
-  explicit TypeError(const std::string& expected,
-      dynamic::Type actual1, dynamic::Type actual2)
-    : std::runtime_error(to<std::string>("TypeError: expected dynamic "
-        "types `", expected, '\'', ", but had types `",
-        dynamic::typeName(actual1), "' and `", dynamic::typeName(actual2),
-        '\''))
-  {}
-};
+//////////////////////////////////////////////////////////////////////
 
 /*
  * We're doing this instead of a simple member typedef to avoid the
@@ -161,12 +149,7 @@ struct dynamic::ObjectMaker {
   friend struct dynamic;
 
   explicit ObjectMaker() : val_(dynamic::object) {}
-  explicit ObjectMaker(dynamic const& key, dynamic val)
-    : val_(dynamic::object)
-  {
-    val_.insert(key, std::move(val));
-  }
-  explicit ObjectMaker(dynamic&& key, dynamic val)
+  explicit ObjectMaker(dynamic key, dynamic val)
     : val_(dynamic::object)
   {
     val_.insert(std::move(key), std::move(val));
@@ -179,34 +162,68 @@ struct dynamic::ObjectMaker {
   ObjectMaker& operator=(ObjectMaker const&) = delete;
   ObjectMaker& operator=(ObjectMaker&&) = delete;
 
-  // These return rvalue-references instead of lvalue-references to allow
-  // constructs like this to moved instead of copied:
+  // This returns an rvalue-reference instead of an lvalue-reference
+  // to allow constructs like this to moved instead of copied:
   //  dynamic a = dynamic::object("a", "b")("c", "d")
-  ObjectMaker&& operator()(dynamic const& key, dynamic val) {
-    val_.insert(key, std::move(val));
-    return std::move(*this);
-  }
-
-  ObjectMaker&& operator()(dynamic&& key, dynamic val) {
+  ObjectMaker&& operator()(dynamic key, dynamic val) {
     val_.insert(std::move(key), std::move(val));
     return std::move(*this);
   }
 
-private:
+ private:
   dynamic val_;
 };
 
-template<class... Args>
-inline dynamic::ObjectMaker dynamic::object(Args&&... args) {
-  return dynamic::ObjectMaker(std::forward<Args>(args)...);
+inline void dynamic::array(EmptyArrayTag) {}
+
+template <class... Args>
+inline dynamic dynamic::array(Args&& ...args) {
+  return dynamic(Array{std::forward<Args>(args)...});
+}
+
+inline dynamic::ObjectMaker dynamic::object() { return ObjectMaker(); }
+inline dynamic::ObjectMaker dynamic::object(dynamic a, dynamic b) {
+  return ObjectMaker(std::move(a), std::move(b));
 }
 
 //////////////////////////////////////////////////////////////////////
 
+struct dynamic::item_iterator : boost::iterator_adaptor<
+                                    dynamic::item_iterator,
+                                    dynamic::ObjectImpl::iterator> {
+  /* implicit */ item_iterator(base_type b) : iterator_adaptor_(b) {}
+
+  using object_type = dynamic::ObjectImpl;
+
+ private:
+  friend class boost::iterator_core_access;
+};
+
+struct dynamic::value_iterator : boost::iterator_adaptor<
+                                     dynamic::value_iterator,
+                                     dynamic::ObjectImpl::iterator,
+                                     dynamic> {
+  /* implicit */ value_iterator(base_type b) : iterator_adaptor_(b) {}
+
+  using object_type = dynamic::ObjectImpl;
+
+ private:
+  dynamic& dereference() const {
+    return base_reference()->second;
+  }
+  friend class boost::iterator_core_access;
+};
+
 struct dynamic::const_item_iterator
   : boost::iterator_adaptor<dynamic::const_item_iterator,
                             dynamic::ObjectImpl::const_iterator> {
   /* implicit */ const_item_iterator(base_type b) : iterator_adaptor_(b) { }
+  /* implicit */ const_item_iterator(item_iterator i)
+      : iterator_adaptor_(i.base()) {}
+  /* implicit */ const_item_iterator(dynamic::ObjectImpl::iterator i)
+      : iterator_adaptor_(i) {}
+
+  using object_type = dynamic::ObjectImpl const;
 
  private:
   friend class boost::iterator_core_access;
@@ -218,6 +235,8 @@ struct dynamic::const_key_iterator
                             dynamic const> {
   /* implicit */ const_key_iterator(base_type b) : iterator_adaptor_(b) { }
 
+  using object_type = dynamic::ObjectImpl const;
+
  private:
   dynamic const& dereference() const {
     return base_reference()->first;
@@ -230,6 +249,12 @@ struct dynamic::const_value_iterator
                             dynamic::ObjectImpl::const_iterator,
                             dynamic const> {
   /* implicit */ const_value_iterator(base_type b) : iterator_adaptor_(b) { }
+  /* implicit */ const_value_iterator(value_iterator i)
+      : iterator_adaptor_(i.base()) {}
+  /* implicit */ const_value_iterator(dynamic::ObjectImpl::iterator i)
+      : iterator_adaptor_(i) {}
+
+  using object_type = dynamic::ObjectImpl const;
 
  private:
   dynamic const& dereference() const {
@@ -240,28 +265,38 @@ struct dynamic::const_value_iterator
 
 //////////////////////////////////////////////////////////////////////
 
+inline dynamic::dynamic() : dynamic(nullptr) {}
+
+inline dynamic::dynamic(std::nullptr_t) : type_(NULLT) {}
+
+inline dynamic::dynamic(void (*)(EmptyArrayTag))
+  : type_(ARRAY)
+{
+  new (&u_.array) Array();
+}
+
 inline dynamic::dynamic(ObjectMaker (*)())
   : type_(OBJECT)
 {
   new (getAddress<ObjectImpl>()) ObjectImpl();
 }
 
-inline dynamic::dynamic(char const* s)
+inline dynamic::dynamic(StringPiece s)
   : type_(STRING)
 {
-  new (&u_.string) fbstring(s);
+  new (&u_.string) std::string(s.data(), s.size());
 }
 
-inline dynamic::dynamic(std::string const& s)
+inline dynamic::dynamic(char const* s)
   : type_(STRING)
 {
-  new (&u_.string) fbstring(s);
+  new (&u_.string) std::string(s);
 }
 
-inline dynamic::dynamic(std::initializer_list<dynamic> il)
-  : type_(ARRAY)
+inline dynamic::dynamic(std::string s)
+  : type_(STRING)
 {
-  new (&u_.array) Array(il.begin(), il.end());
+  new (&u_.string) std::string(std::move(s));
 }
 
 inline dynamic::dynamic(ObjectMaker&& maker)
@@ -277,22 +312,45 @@ inline dynamic::dynamic(dynamic const& o)
   *this = o;
 }
 
-inline dynamic::dynamic(dynamic&& o)
+inline dynamic::dynamic(dynamic&& o) noexcept
   : type_(NULLT)
 {
   *this = std::move(o);
 }
 
-inline dynamic::~dynamic() { destroy(); }
+inline dynamic::~dynamic() noexcept { destroy(); }
+
+// Integral types except bool convert to int64_t, float types to double.
+template <class T>
+struct dynamic::NumericTypeHelper<
+    T, typename std::enable_if<std::is_integral<T>::value>::type> {
+  static_assert(
+      !kIsObjC || sizeof(T) > sizeof(char),
+      "char-sized types are ambiguous in objc; cast to bool or wider type");
+  using type = int64_t;
+};
+template <>
+struct dynamic::NumericTypeHelper<bool> {
+  using type = bool;
+};
+template <>
+struct dynamic::NumericTypeHelper<float> {
+  using type = double;
+};
+template <>
+struct dynamic::NumericTypeHelper<double> {
+  using type = double;
+};
 
-template<class T>
+template <
+    class T,
+    class NumericType /* = typename NumericTypeHelper<T>::type */>
 dynamic::dynamic(T t) {
-  typedef typename detail::ConversionHelper<T>::type U;
-  type_ = TypeInfo<U>::type;
-  new (getAddress<U>()) U(std::move(t));
+  type_ = TypeInfo<NumericType>::type;
+  new (getAddress<NumericType>()) NumericType(NumericType(t));
 }
 
-template<class Iterator>
+template <class Iterator>
 dynamic::dynamic(Iterator first, Iterator last)
   : type_(ARRAY)
 {
@@ -308,11 +366,20 @@ inline dynamic::const_iterator dynamic::end() const {
   return get<Array>().end();
 }
 
+inline dynamic::iterator dynamic::begin() {
+  return get<Array>().begin();
+}
+inline dynamic::iterator dynamic::end() {
+  return get<Array>().end();
+}
+
 template <class It>
 struct dynamic::IterableProxy {
-  typedef It const_iterator;
+  typedef It iterator;
+  typedef typename It::value_type value_type;
+  typedef typename It::object_type object_type;
 
-  /* implicit */ IterableProxy(const dynamic::ObjectImpl* o) : o_(o) { }
+  /* implicit */ IterableProxy(object_type* o) : o_(o) {}
 
   It begin() const {
     return o_->begin();
@@ -323,7 +390,7 @@ struct dynamic::IterableProxy {
   }
 
  private:
-  const dynamic::ObjectImpl* o_;
+  object_type* o_;
 };
 
 inline dynamic::IterableProxy<dynamic::const_key_iterator> dynamic::keys()
@@ -341,68 +408,108 @@ inline dynamic::IterableProxy<dynamic::const_item_iterator> dynamic::items()
   return &(get<ObjectImpl>());
 }
 
-inline bool dynamic::isString() const { return get_nothrow<fbstring>(); }
-inline bool dynamic::isObject() const { return get_nothrow<ObjectImpl>(); }
-inline bool dynamic::isBool()   const { return get_nothrow<bool>(); }
-inline bool dynamic::isArray()  const { return get_nothrow<Array>(); }
-inline bool dynamic::isDouble() const { return get_nothrow<double>(); }
-inline bool dynamic::isInt()    const { return get_nothrow<int64_t>(); }
-inline bool dynamic::isNull()   const { return get_nothrow<void*>(); }
-inline bool dynamic::isNumber() const { return isInt() || isDouble(); }
+inline dynamic::IterableProxy<dynamic::value_iterator> dynamic::values() {
+  return &(get<ObjectImpl>());
+}
+
+inline dynamic::IterableProxy<dynamic::item_iterator> dynamic::items() {
+  return &(get<ObjectImpl>());
+}
+
+inline bool dynamic::isString() const {
+  return get_nothrow<std::string>() != nullptr;
+}
+inline bool dynamic::isObject() const {
+  return get_nothrow<ObjectImpl>() != nullptr;
+}
+inline bool dynamic::isBool() const {
+  return get_nothrow<bool>() != nullptr;
+}
+inline bool dynamic::isArray() const {
+  return get_nothrow<Array>() != nullptr;
+}
+inline bool dynamic::isDouble() const {
+  return get_nothrow<double>() != nullptr;
+}
+inline bool dynamic::isInt() const {
+  return get_nothrow<int64_t>() != nullptr;
+}
+inline bool dynamic::isNull() const {
+  return get_nothrow<std::nullptr_t>() != nullptr;
+}
+inline bool dynamic::isNumber() const {
+  return isInt() || isDouble();
+}
 
 inline dynamic::Type dynamic::type() const {
   return type_;
 }
 
-inline fbstring dynamic::asString() const { return asImpl<fbstring>(); }
-inline double   dynamic::asDouble() const { return asImpl<double>(); }
-inline int64_t  dynamic::asInt()    const { return asImpl<int64_t>(); }
-inline bool     dynamic::asBool()   const { return asImpl<bool>(); }
+inline std::string dynamic::asString() const {
+  return asImpl<std::string>();
+}
+inline double dynamic::asDouble() const {
+  return asImpl<double>();
+}
+inline int64_t dynamic::asInt() const {
+  return asImpl<int64_t>();
+}
+inline bool dynamic::asBool() const {
+  return asImpl<bool>();
+}
+
+inline const std::string& dynamic::getString() const& {
+  return get<std::string>();
+}
+inline double          dynamic::getDouble() const& { return get<double>(); }
+inline int64_t         dynamic::getInt()    const& { return get<int64_t>(); }
+inline bool            dynamic::getBool()   const& { return get<bool>(); }
+
+inline std::string& dynamic::getString()& {
+  return get<std::string>();
+}
+inline double&   dynamic::getDouble() & { return get<double>(); }
+inline int64_t&  dynamic::getInt()    & { return get<int64_t>(); }
+inline bool&     dynamic::getBool()   & { return get<bool>(); }
 
-template<class T>
+inline std::string&& dynamic::getString()&& {
+  return std::move(get<std::string>());
+}
+inline double   dynamic::getDouble() && { return get<double>(); }
+inline int64_t  dynamic::getInt()    && { return get<int64_t>(); }
+inline bool     dynamic::getBool()   && { return get<bool>(); }
+
+inline const char* dynamic::data() const& {
+  return get<std::string>().data();
+}
+inline const char* dynamic::c_str() const& {
+  return get<std::string>().c_str();
+}
+inline StringPiece dynamic::stringPiece() const {
+  return get<std::string>();
+}
+
+template <class T>
 struct dynamic::CompareOp {
   static bool comp(T const& a, T const& b) { return a < b; }
 };
-template<>
+template <>
 struct dynamic::CompareOp<dynamic::ObjectImpl> {
-  static bool comp(ObjectImpl const& a, ObjectImpl const& b) {
+  static bool comp(ObjectImpl const&, ObjectImpl const&) {
     // This code never executes; it is just here for the compiler.
     return false;
   }
 };
-
-inline bool dynamic::operator<(dynamic const& o) const {
-  if (UNLIKELY(type_ == OBJECT || o.type_ == OBJECT)) {
-    throw TypeError("object", type_);
-  }
-  if (type_ != o.type_) {
-    return type_ < o.type_;
-  }
-
-#define FB_X(T) return CompareOp<T>::comp(*getAddress<T>(),   \
-                                          *o.getAddress<T>())
-  FB_DYNAMIC_APPLY(type_, FB_X);
-#undef FB_X
-}
-
-inline bool dynamic::operator==(dynamic const& o) const {
-  if (type() != o.type()) {
-    if (isNumber() && o.isNumber()) {
-      auto& integ = isInt() ? *this : o;
-      auto& doubl = isInt() ? o     : *this;
-      return integ.asInt() == doubl.asDouble();
-    }
-    return false;
+template <>
+struct dynamic::CompareOp<std::nullptr_t> {
+  static bool comp(std::nullptr_t const&, std::nullptr_t const&) {
+    return true;
   }
-
-#define FB_X(T) return *getAddress<T>() == *o.getAddress<T>();
-  FB_DYNAMIC_APPLY(type_, FB_X);
-#undef FB_X
-}
+};
 
 inline dynamic& dynamic::operator+=(dynamic const& o) {
   if (type() == STRING && o.type() == STRING) {
-    *getAddress<fbstring>() += *o.getAddress<fbstring>();
+    *getAddress<std::string>() += *o.getAddress<std::string>();
     return *this;
   }
   *this = detail::numericOp<std::plus>(*this, o);
@@ -424,13 +531,13 @@ inline dynamic& dynamic::operator/=(dynamic const& o) {
   return *this;
 }
 
-#define FB_DYNAMIC_INTEGER_OP(op)                           \
-  inline dynamic& dynamic::operator op(dynamic const& o) {  \
-    if (!isInt() || !o.isInt()) {                           \
-      throw TypeError("int64", type(), o.type());           \
-    }                                                       \
-    *getAddress<int64_t>() op o.asInt();                    \
-    return *this;                                           \
+#define FB_DYNAMIC_INTEGER_OP(op)                          \
+  inline dynamic& dynamic::operator op(dynamic const& o) { \
+    if (!isInt() || !o.isInt()) {                          \
+      throwTypeError_("int64", type(), o.type());          \
+    }                                                      \
+    *getAddress<int64_t>() op o.asInt();                   \
+    return *this;                                          \
   }
 
 FB_DYNAMIC_INTEGER_OP(%=)
@@ -450,93 +557,41 @@ inline dynamic& dynamic::operator--() {
   return *this;
 }
 
-inline dynamic& dynamic::operator=(dynamic const& o) {
-  if (&o != this) {
-    destroy();
-#define FB_X(T) new (getAddress<T>()) T(*o.getAddress<T>())
-    FB_DYNAMIC_APPLY(o.type_, FB_X);
-#undef FB_X
-    type_ = o.type_;
-  }
-  return *this;
+inline dynamic const& dynamic::operator[](dynamic const& idx) const& {
+  return at(idx);
 }
 
-inline dynamic& dynamic::operator=(dynamic&& o) {
-  if (&o != this) {
-    destroy();
-#define FB_X(T) new (getAddress<T>()) T(std::move(*o.getAddress<T>()))
-    FB_DYNAMIC_APPLY(o.type_, FB_X);
-#undef FB_X
-    type_ = o.type_;
-  }
-  return *this;
+inline dynamic&& dynamic::operator[](dynamic const& idx) && {
+  return std::move((*this)[idx]);
 }
 
-inline dynamic& dynamic::operator[](dynamic const& k) {
-  if (!isObject() && !isArray()) {
-    throw TypeError("object/array", type());
-  }
-  if (isArray()) {
-    return at(k);
-  }
+template <class K, class V> inline dynamic& dynamic::setDefault(K&& k, V&& v) {
   auto& obj = get<ObjectImpl>();
-  auto ret = obj.insert({k, nullptr});
-  return ret.first->second;
-}
-
-inline dynamic const& dynamic::operator[](dynamic const& idx) const {
-  return at(idx);
+  return obj.insert(std::make_pair(std::forward<K>(k),
+                                   std::forward<V>(v))).first->second;
 }
 
-inline dynamic dynamic::getDefault(const dynamic& k, const dynamic& v) const {
+template <class K> inline dynamic& dynamic::setDefault(K&& k, dynamic&& v) {
   auto& obj = get<ObjectImpl>();
-  auto it = obj.find(k);
-  return it == obj.end() ? v : it->second;
+  return obj.insert(std::make_pair(std::forward<K>(k),
+                                   std::move(v))).first->second;
 }
 
-inline dynamic&& dynamic::getDefault(const dynamic& k, dynamic&& v) const {
+template <class K> inline dynamic& dynamic::setDefault(K&& k, const dynamic& v) {
   auto& obj = get<ObjectImpl>();
-  auto it = obj.find(k);
-  if (it != obj.end()) {
-    v = it->second;
-  }
-
-  return std::move(v);
+  return obj.insert(std::make_pair(std::forward<K>(k), v)).first->second;
 }
 
-template<class K, class V> inline dynamic& dynamic::setDefault(K&& k, V&& v) {
-  auto& obj = get<ObjectImpl>();
-  return obj.insert(std::make_pair(std::forward<K>(k),
-                                   std::forward<V>(v))).first->second;
+inline dynamic* dynamic::get_ptr(dynamic const& idx) & {
+  return const_cast<dynamic*>(const_cast<dynamic const*>(this)->get_ptr(idx));
 }
 
-inline dynamic const& dynamic::at(dynamic const& idx) const {
-  return const_cast<dynamic*>(this)->at(idx);
+inline dynamic& dynamic::at(dynamic const& idx) & {
+  return const_cast<dynamic&>(const_cast<dynamic const*>(this)->at(idx));
 }
 
-inline dynamic& dynamic::at(dynamic const& idx) {
-  if (!isObject() && !isArray()) {
-    throw TypeError("object/array", type());
-  }
-
-  if (auto* parray = get_nothrow<Array>()) {
-    if (idx >= parray->size()) {
-      throw std::out_of_range("out of range in dynamic array");
-    }
-    if (!idx.isInt()) {
-      throw TypeError("int64", idx.type());
-    }
-    return (*parray)[idx.asInt()];
-  }
-
-  auto* pobj = get_nothrow<ObjectImpl>();
-  assert(pobj);
-  auto it = find(idx);
-  if (it == items().end()) {
-    throw std::out_of_range(to<std::string>(
-        "couldn't find key ", idx.asString(), " in dynamic object"));
-  }
-  return const_cast<dynamic&>(it->second);
+inline dynamic&& dynamic::at(dynamic const& idx) && {
+  return std::move(at(idx));
 }
 
 inline bool dynamic::empty() const {
@@ -546,46 +601,64 @@ inline bool dynamic::empty() const {
   return !size();
 }
 
-inline std::size_t dynamic::size() const {
-  if (auto* ar = get_nothrow<Array>()) {
-    return ar->size();
-  }
-  if (auto* obj = get_nothrow<ObjectImpl>()) {
-    return obj->size();
-  }
-  if (auto* str = get_nothrow<fbstring>()) {
-    return str->size();
-  }
-  throw TypeError("array/object", type());
-}
-
 inline std::size_t dynamic::count(dynamic const& key) const {
-  return find(key) != items().end();
+  return find(key) != items().end() ? 1u : 0u;
 }
 
 inline dynamic::const_item_iterator dynamic::find(dynamic const& key) const {
   return get<ObjectImpl>().find(key);
 }
+inline dynamic::item_iterator dynamic::find(dynamic const& key) {
+  return get<ObjectImpl>().find(key);
+}
 
-template<class K, class V> inline void dynamic::insert(K&& key, V&& val) {
+template <class K, class V> inline void dynamic::insert(K&& key, V&& val) {
   auto& obj = get<ObjectImpl>();
-  auto rv = obj.insert(std::make_pair(std::forward<K>(key),
-                                      std::forward<V>(val)));
-  if (!rv.second) {
-    // note, the second use of std:forward<V>(val) is only correct
-    // if the first one did not result in a move. obj[key] = val
-    // would be preferrable but doesn't compile because dynamic
-    // is (intentionally) not default constructable
-    rv.first->second = std::forward<V>(val);
+  auto rv = obj.insert({ std::forward<K>(key), nullptr });
+  rv.first->second = std::forward<V>(val);
+}
+
+inline void dynamic::update(const dynamic& mergeObj) {
+  if (!isObject() || !mergeObj.isObject()) {
+    throwTypeError_("object", type(), mergeObj.type());
+  }
+
+  for (const auto& pair : mergeObj.items()) {
+    (*this)[pair.first] = pair.second;
   }
 }
 
+inline void dynamic::update_missing(const dynamic& mergeObj1) {
+  if (!isObject() || !mergeObj1.isObject()) {
+    throwTypeError_("object", type(), mergeObj1.type());
+  }
+
+  // Only add if not already there
+  for (const auto& pair : mergeObj1.items()) {
+    if ((*this).find(pair.first) == (*this).items().end()) {
+      (*this)[pair.first] = pair.second;
+    }
+  }
+}
+
+inline dynamic dynamic::merge(
+    const dynamic& mergeObj1,
+    const dynamic& mergeObj2) {
+
+  // No checks on type needed here because they are done in update_missing
+  // Note that we do update_missing here instead of update() because
+  // it will prevent the extra writes that would occur with update()
+  auto ret = mergeObj2;
+  ret.update_missing(mergeObj1);
+  return ret;
+}
+
 inline std::size_t dynamic::erase(dynamic const& key) {
   auto& obj = get<ObjectImpl>();
   return obj.erase(key);
 }
 
-inline dynamic::const_iterator dynamic::erase(const_iterator it) {
+inline dynamic::iterator dynamic::erase(const_iterator it) {
   auto& arr = get<Array>();
   // std::vector doesn't have an erase method that works on const iterators,
   // even though the standard says it should, so this hack converts to a
@@ -593,202 +666,188 @@ inline dynamic::const_iterator dynamic::erase(const_iterator it) {
   return get<Array>().erase(arr.begin() + (it - arr.begin()));
 }
 
-inline dynamic::const_iterator
-dynamic::erase(const_iterator first, const_iterator last) {
-  auto& arr = get<Array>();
-  return get<Array>().erase(
-    arr.begin() + (first - arr.begin()),
-    arr.begin() + (last - arr.begin()));
-}
-
 inline dynamic::const_key_iterator dynamic::erase(const_key_iterator it) {
   return const_key_iterator(get<ObjectImpl>().erase(it.base()));
 }
 
-inline dynamic::const_key_iterator dynamic::erase(const_key_iterator first,
-                                                  const_key_iterator last) {
+inline dynamic::const_key_iterator dynamic::erase(
+    const_key_iterator first,
+    const_key_iterator last) {
   return const_key_iterator(get<ObjectImpl>().erase(first.base(),
                                                     last.base()));
 }
 
-inline dynamic::const_value_iterator dynamic::erase(const_value_iterator it) {
-  return const_value_iterator(get<ObjectImpl>().erase(it.base()));
+inline dynamic::value_iterator dynamic::erase(const_value_iterator it) {
+  return value_iterator(get<ObjectImpl>().erase(it.base()));
 }
 
-inline dynamic::const_value_iterator dynamic::erase(const_value_iterator first,
-                                                    const_value_iterator last) {
-  return const_value_iterator(get<ObjectImpl>().erase(first.base(),
-                                                      last.base()));
+inline dynamic::value_iterator dynamic::erase(
+    const_value_iterator first,
+    const_value_iterator last) {
+  return value_iterator(get<ObjectImpl>().erase(first.base(), last.base()));
 }
 
-inline dynamic::const_item_iterator dynamic::erase(const_item_iterator it) {
-  return const_item_iterator(get<ObjectImpl>().erase(it.base()));
+inline dynamic::item_iterator dynamic::erase(const_item_iterator it) {
+  return item_iterator(get<ObjectImpl>().erase(it.base()));
 }
 
-inline dynamic::const_item_iterator dynamic::erase(const_item_iterator first,
-                                                   const_item_iterator last) {
-  return const_item_iterator(get<ObjectImpl>().erase(first.base(),
-                                                     last.base()));
+inline dynamic::item_iterator dynamic::erase(
+    const_item_iterator first,
+    const_item_iterator last) {
+  return item_iterator(get<ObjectImpl>().erase(first.base(), last.base()));
 }
 
 inline void dynamic::resize(std::size_t sz, dynamic const& c) {
-  auto& array = get<Array>();
-  array.resize(sz, c);
+  auto& arr = get<Array>();
+  arr.resize(sz, c);
 }
 
 inline void dynamic::push_back(dynamic const& v) {
-  auto& array = get<Array>();
-  array.push_back(v);
+  auto& arr = get<Array>();
+  arr.push_back(v);
 }
 
 inline void dynamic::push_back(dynamic&& v) {
-  auto& array = get<Array>();
-  array.push_back(std::move(v));
+  auto& arr = get<Array>();
+  arr.push_back(std::move(v));
 }
 
 inline void dynamic::pop_back() {
-  auto& array = get<Array>();
-  array.pop_back();
+  auto& arr = get<Array>();
+  arr.pop_back();
 }
 
-inline std::size_t dynamic::hash() const {
-  switch (type()) {
-  case OBJECT:
-  case ARRAY:
-  case NULLT:
-    throw TypeError("not null/object/array", type());
-  case INT64:
-    return std::hash<int64_t>()(asInt());
-  case DOUBLE:
-    return std::hash<double>()(asDouble());
-  case BOOL:
-    return std::hash<bool>()(asBool());
-  case STRING:
-    return std::hash<fbstring>()(asString());
-  default:
-    CHECK(0); abort();
-  }
+//////////////////////////////////////////////////////////////////////
+
+inline dynamic::dynamic(Array&& r) : type_(ARRAY) {
+  new (&u_.array) Array(std::move(r));
 }
 
-//////////////////////////////////////////////////////////////////////
+#define FOLLY_DYNAMIC_DEC_TYPEINFO(T, str, val) \
+  template <> struct dynamic::TypeInfo<T> { \
+    static constexpr const char* name = str; \
+    static constexpr dynamic::Type type = val; \
+  }; \
+  //
 
-template<class T> struct dynamic::TypeInfo {
-  static char const name[];
-  static Type const type;
-};
+FOLLY_DYNAMIC_DEC_TYPEINFO(std::nullptr_t,      "null",    dynamic::NULLT)
+FOLLY_DYNAMIC_DEC_TYPEINFO(bool,                "boolean", dynamic::BOOL)
+FOLLY_DYNAMIC_DEC_TYPEINFO(std::string,         "string",  dynamic::STRING)
+FOLLY_DYNAMIC_DEC_TYPEINFO(dynamic::Array,      "array",   dynamic::ARRAY)
+FOLLY_DYNAMIC_DEC_TYPEINFO(double,              "double",  dynamic::DOUBLE)
+FOLLY_DYNAMIC_DEC_TYPEINFO(int64_t,             "int64",   dynamic::INT64)
+FOLLY_DYNAMIC_DEC_TYPEINFO(dynamic::ObjectImpl, "object",  dynamic::OBJECT)
 
-template<class T>
+#undef FOLLY_DYNAMIC_DEC_TYPEINFO
+
+template <class T>
 T dynamic::asImpl() const {
   switch (type()) {
   case INT64:    return to<T>(*get_nothrow<int64_t>());
   case DOUBLE:   return to<T>(*get_nothrow<double>());
   case BOOL:     return to<T>(*get_nothrow<bool>());
-  case STRING:   return to<T>(*get_nothrow<fbstring>());
+  case STRING:
+    return to<T>(*get_nothrow<std::string>());
   default:
-    throw TypeError("int/double/bool/string", type());
+    throwTypeError_("int/double/bool/string", type());
   }
 }
 
 // Return a T* to our type, or null if we're not that type.
-template<class T>
-T* dynamic::get_nothrow() {
+template <class T>
+T* dynamic::get_nothrow() & noexcept {
   if (type_ != TypeInfo<T>::type) {
     return nullptr;
   }
   return getAddress<T>();
 }
 
-template<class T>
-T const* dynamic::get_nothrow() const {
+template <class T>
+T const* dynamic::get_nothrow() const& noexcept {
   return const_cast<dynamic*>(this)->get_nothrow<T>();
 }
 
 // Return T* for where we can put a T, without type checking.  (Memory
 // might be uninitialized, even.)
-template<class T>
-T* dynamic::getAddress() {
+template <class T>
+T* dynamic::getAddress() noexcept {
   return GetAddrImpl<T>::get(u_);
 }
 
-template<class T>
-T const* dynamic::getAddress() const {
+template <class T>
+T const* dynamic::getAddress() const noexcept {
   return const_cast<dynamic*>(this)->getAddress<T>();
 }
 
-template<class T> struct dynamic::GetAddrImpl {};
-template<> struct dynamic::GetAddrImpl<void*> {
-  static void** get(Data& d) { return &d.nul; }
+template <class T> struct dynamic::GetAddrImpl {};
+template <> struct dynamic::GetAddrImpl<std::nullptr_t> {
+  static std::nullptr_t* get(Data& d) noexcept { return &d.nul; }
 };
-template<> struct dynamic::GetAddrImpl<dynamic::Array> {
-  static Array* get(Data& d) { return &d.array; }
+template <> struct dynamic::GetAddrImpl<dynamic::Array> {
+  static Array* get(Data& d) noexcept { return &d.array; }
 };
-template<> struct dynamic::GetAddrImpl<bool> {
-  static bool* get(Data& d) { return &d.boolean; }
+template <> struct dynamic::GetAddrImpl<bool> {
+  static bool* get(Data& d) noexcept { return &d.boolean; }
 };
-template<> struct dynamic::GetAddrImpl<int64_t> {
-  static int64_t* get(Data& d) { return &d.integer; }
+template <> struct dynamic::GetAddrImpl<int64_t> {
+  static int64_t* get(Data& d) noexcept { return &d.integer; }
 };
-template<> struct dynamic::GetAddrImpl<double> {
-  static double* get(Data& d) { return &d.doubl; }
+template <> struct dynamic::GetAddrImpl<double> {
+  static double* get(Data& d) noexcept { return &d.doubl; }
 };
-template<> struct dynamic::GetAddrImpl<fbstring> {
-  static fbstring* get(Data& d) { return &d.string; }
+template <>
+struct dynamic::GetAddrImpl<std::string> {
+  static std::string* get(Data& d) noexcept {
+    return &d.string;
+  }
 };
-template<> struct dynamic::GetAddrImpl<dynamic::ObjectImpl> {
+template <> struct dynamic::GetAddrImpl<dynamic::ObjectImpl> {
   static_assert(sizeof(ObjectImpl) <= sizeof(Data::objectBuffer),
     "In your implementation, std::unordered_map<> apparently takes different"
     " amount of space depending on its template parameters.  This is "
     "weird.  Make objectBuffer bigger if you want to compile dynamic.");
 
-  static ObjectImpl* get(Data& d) {
+  static ObjectImpl* get(Data& d) noexcept {
     void* data = &d.objectBuffer;
     return static_cast<ObjectImpl*>(data);
   }
 };
 
-template<class T>
+template <class T>
 T& dynamic::get() {
   if (auto* p = get_nothrow<T>()) {
     return *p;
   }
-  throw TypeError(TypeInfo<T>::name, type());
+  throwTypeError_(TypeInfo<T>::name, type());
 }
 
-template<class T>
+template <class T>
 T const& dynamic::get() const {
   return const_cast<dynamic*>(this)->get<T>();
 }
 
-inline char const* dynamic::typeName(Type t) {
-#define FB_X(T) return TypeInfo<T>::name
-  FB_DYNAMIC_APPLY(t, FB_X);
-#undef FB_X
-}
-
-inline void dynamic::destroy() {
-  // This short-circuit speeds up some microbenchmarks.
-  if (type_ == NULLT) return;
-
-#define FB_X(T) detail::Destroy::destroy(getAddress<T>())
-  FB_DYNAMIC_APPLY(type_, FB_X);
-#undef FB_X
-  type_ = NULLT;
-  u_.nul = nullptr;
-}
-
 //////////////////////////////////////////////////////////////////////
 
 /*
  * Helper for implementing operator<<.  Throws if the type shouldn't
  * support it.
  */
-template<class T>
+template <class T>
 struct dynamic::PrintImpl {
   static void print(dynamic const&, std::ostream& out, T const& t) {
     out << t;
   }
 };
-template<>
+// Otherwise, null, being (void*)0, would print as 0.
+template <>
+struct dynamic::PrintImpl<std::nullptr_t> {
+  static void print(dynamic const& /* d */,
+                    std::ostream& out,
+                    std::nullptr_t const&) {
+    out << "null";
+  }
+};
+template <>
 struct dynamic::PrintImpl<dynamic::ObjectImpl> {
   static void print(dynamic const& d,
                     std::ostream& out,
@@ -796,7 +855,7 @@ struct dynamic::PrintImpl<dynamic::ObjectImpl> {
     d.print_as_pseudo_json(out);
   }
 };
-template<>
+template <>
 struct dynamic::PrintImpl<dynamic::Array> {
   static void print(dynamic const& d,
                     std::ostream& out,
@@ -837,7 +896,7 @@ class FormatValue<dynamic> {
       FormatValue<int64_t>(val_.asInt()).format(arg, cb);
       break;
     case dynamic::STRING:
-      FormatValue<fbstring>(val_.asString()).format(arg, cb);
+      FormatValue<std::string>(val_.asString()).format(arg, cb);
       break;
     case dynamic::DOUBLE:
       FormatValue<double>(val_.asDouble()).format(arg, cb);
@@ -846,7 +905,7 @@ class FormatValue<dynamic> {
       FormatValue(val_.at(arg.splitIntKey())).format(arg, cb);
       break;
     case dynamic::OBJECT:
-      FormatValue(val_.at(arg.splitKey().toFbstring())).format(arg, cb);
+      FormatValue(val_.at(arg.splitKey().toString())).format(arg, cb);
       break;
     }
   }
@@ -855,8 +914,51 @@ class FormatValue<dynamic> {
   const dynamic& val_;
 };
 
-}
+template <class V>
+class FormatValue<detail::DefaultValueWrapper<dynamic, V>> {
+ public:
+  explicit FormatValue(
+      const detail::DefaultValueWrapper<dynamic, V>& val)
+    : val_(val) { }
 
-#undef FB_DYNAMIC_APPLY
+  template <class FormatCallback>
+  void format(FormatArg& arg, FormatCallback& cb) const {
+    auto& c = val_.container;
+    switch (c.type()) {
+    case dynamic::NULLT:
+    case dynamic::BOOL:
+    case dynamic::INT64:
+    case dynamic::STRING:
+    case dynamic::DOUBLE:
+      FormatValue<dynamic>(c).format(arg, cb);
+      break;
+    case dynamic::ARRAY:
+      {
+        int key = arg.splitIntKey();
+        if (key >= 0 && size_t(key) < c.size()) {
+          FormatValue<dynamic>(c.at(key)).format(arg, cb);
+        } else{
+          FormatValue<V>(val_.defaultValue).format(arg, cb);
+        }
+      }
+      break;
+    case dynamic::OBJECT:
+      {
+        auto pos = c.find(arg.splitKey());
+        if (pos != c.items().end()) {
+          FormatValue<dynamic>(pos->second).format(arg, cb);
+        } else {
+          FormatValue<V>(val_.defaultValue).format(arg, cb);
+        }
+      }
+      break;
+    }
+  }
+
+ private:
+  const detail::DefaultValueWrapper<dynamic, V>& val_;
+};
+
+} // namespace folly
 
-#endif
+#undef FB_DYNAMIC_APPLY