X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=folly%2FDynamicConverter.h;h=e63bf842666c58ad6d19db25b262cfd736e13a6a;hb=b3aabafd2d5306d85105bcdb55b2c2422628ecaa;hp=2f0a1205888e9b15e1b1e98f61cca9abfb636add;hpb=981ed98473314f0e3df5e0c4d47c8574d9523289;p=folly.git

diff --git a/folly/DynamicConverter.h b/folly/DynamicConverter.h
index 2f0a1205..e63bf842 100644
--- a/folly/DynamicConverter.h
+++ b/folly/DynamicConverter.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.
@@ -16,12 +16,22 @@
 
 // @author Nicholas Ormrod <njormrod@fb.com>
 
-#ifndef DYNAMIC_CONVERTER_H
-#define DYNAMIC_CONVERTER_H
+#pragma once
+
+#include <iterator>
+#include <type_traits>
+
+#include <boost/iterator/iterator_adaptor.hpp>
+#include <boost/mpl/has_xxx.hpp>
+
+#include <folly/Likely.h>
+#include <folly/Optional.h>
+#include <folly/Traits.h>
+#include <folly/dynamic.h>
 
-#include "folly/dynamic.h"
 namespace folly {
   template <typename T> T convertTo(const dynamic&);
+  template <typename T> dynamic toDynamic(const T&);
 }
 
 /**
@@ -29,18 +39,14 @@ namespace folly {
  *
  * Example:
  *
- *   dynamic d = { { 1, 2, 3 }, { 4, 5 } }; // a vector of vector of int
+ *   dynamic d = dynamic::array(
+ *       dynamic::array(1, 2, 3),
+ *       dynamic::array(4, 5)); // a vector of vector of int
  *   auto vvi = convertTo<fbvector<fbvector<int>>>(d);
  *
  * See docs/DynamicConverter.md for supported types and customization
  */
 
-
-#include <type_traits>
-#include <boost/iterator/iterator_adaptor.hpp>
-#include <boost/mpl/has_xxx.hpp>
-#include "folly/Likely.h"
-
 namespace folly {
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -49,42 +55,31 @@ namespace folly {
 namespace dynamicconverter_detail {
 
 BOOST_MPL_HAS_XXX_TRAIT_DEF(value_type);
-BOOST_MPL_HAS_XXX_TRAIT_DEF(key_type);
-BOOST_MPL_HAS_XXX_TRAIT_DEF(mapped_type);
 BOOST_MPL_HAS_XXX_TRAIT_DEF(iterator);
+BOOST_MPL_HAS_XXX_TRAIT_DEF(mapped_type);
+BOOST_MPL_HAS_XXX_TRAIT_DEF(key_type);
 
-template <typename T> struct map_container_has_correct_types
-  : std::is_same<std::pair<typename std::add_const<typename T::key_type>::type,
-                           typename T::mapped_type>,
-                 typename T::value_type> {};
-
-template <typename T> struct class_is_container {
-  struct dummy {};
+template <typename T> struct iterator_class_is_container {
+  typedef std::reverse_iterator<typename T::iterator> some_iterator;
   enum { value = has_value_type<T>::value &&
-                 has_iterator<T>::value &&
-                 std::is_constructible<T, dummy, dummy>::value };
+              std::is_constructible<T, some_iterator, some_iterator>::value };
 };
 
-template <typename T> struct container_is_map
-  : std::conditional<
-      has_key_type<T>::value && has_mapped_type<T>::value,
-      map_container_has_correct_types<T>,
-      std::false_type
-    >::type {};
-
-template <typename T> struct is_container
-  : std::conditional<
-      std::is_class<T>::value,
-      class_is_container<T>,
-      std::false_type
-    >::type {};
-
-template <typename T> struct is_map_container
-  : std::conditional<
-      is_container<T>::value,
-      container_is_map<T>,
-      std::false_type
-    >::type {};
+template <typename T>
+using class_is_container =
+    Conjunction<has_iterator<T>, iterator_class_is_container<T>>;
+
+template <typename T>
+using is_range = StrictConjunction<has_value_type<T>, has_iterator<T>>;
+
+template <typename T>
+using is_container = StrictConjunction<std::is_class<T>, class_is_container<T>>;
+
+template <typename T>
+using is_map = StrictConjunction<is_range<T>, has_mapped_type<T>>;
+
+template <typename T>
+using is_associative = StrictConjunction<is_range<T>, has_key_type<T>>;
 
 } // namespace dynamicconverter_detail
 
@@ -105,53 +100,67 @@ template <typename T> struct is_map_container
 
 namespace dynamicconverter_detail {
 
+template <typename T>
+struct Dereferencer {
+  static inline void derefToCache(
+      Optional<T>* /* mem */,
+      const dynamic::const_item_iterator& /* it */) {
+    throw TypeError("array", dynamic::Type::OBJECT);
+  }
+
+  static inline void derefToCache(
+      Optional<T>* mem,
+      const dynamic::const_iterator& it) {
+    mem->emplace(convertTo<T>(*it));
+  }
+};
+
 template <typename F, typename S>
-inline void
-derefToCache(std::pair<F, S>* mem, const dynamic::const_item_iterator& it) {
-  new (mem) std::pair<F, S>(convertTo<F>(it->first), convertTo<S>(it->second));
-}
+struct Dereferencer<std::pair<F, S>> {
+  static inline void derefToCache(
+      Optional<std::pair<F, S>>* mem,
+      const dynamic::const_item_iterator& it) {
+    mem->emplace(convertTo<F>(it->first), convertTo<S>(it->second));
+  }
 
-template <typename T>
-inline void derefToCache(T* mem, const dynamic::const_iterator& it) {
-  new (mem) T(convertTo<T>(*it));
-}
+  // Intentional duplication of the code in Dereferencer
+  template <typename T>
+  static inline void derefToCache(
+      Optional<T>* mem,
+      const dynamic::const_iterator& it) {
+    mem->emplace(convertTo<T>(*it));
+  }
+};
 
 template <typename T, typename It>
-class Transformer : public boost::iterator_adaptor<
-                             Transformer<T, It>,
-                             It,
-                             typename T::value_type
-                           > {
+class Transformer
+    : public boost::
+          iterator_adaptor<Transformer<T, It>, It, typename T::value_type> {
   friend class boost::iterator_core_access;
 
   typedef typename T::value_type ttype;
 
-  mutable ttype cache_;
-  mutable bool valid_;
+  mutable Optional<ttype> cache_;
 
   void increment() {
     ++this->base_reference();
-    valid_ = false;
+    cache_ = none;
   }
 
   ttype& dereference() const {
-    if (LIKELY(!valid_)) {
-      cache_.~ttype();
-      derefToCache(&cache_, this->base_reference());
-      valid_ = true;
+    if (!cache_) {
+      Dereferencer<ttype>::derefToCache(&cache_, this->base_reference());
     }
-    return cache_;
+    return cache_.value();
   }
 
-public:
-  explicit Transformer(const It& it)
-    : Transformer::iterator_adaptor_(it), valid_(false) {}
+ public:
+  explicit Transformer(const It& it) : Transformer::iterator_adaptor_(it) {}
 };
 
 // conversion factory
 template <typename T, typename It>
-static inline std::move_iterator<Transformer<T, It>>
-conversionIterator(const It& it) {
+inline std::move_iterator<Transformer<T, It>> conversionIterator(const It& it) {
   return std::make_move_iterator(Transformer<T, It>(it));
 }
 
@@ -160,13 +169,14 @@ conversionIterator(const It& it) {
 ///////////////////////////////////////////////////////////////////////////////
 // DynamicConverter specializations
 
-template <typename T, typename Enable = void> struct DynamicConverter;
-
 /**
  * Each specialization of DynamicConverter has the function
- *     'static T convert(const dynamic& d);'
+ *     'static T convert(const dynamic&);'
  */
 
+// default - intentionally unimplemented
+template <typename T, typename Enable = void> struct DynamicConverter;
+
 // boolean
 template <>
 struct DynamicConverter<bool> {
@@ -177,20 +187,33 @@ struct DynamicConverter<bool> {
 
 // integrals
 template <typename T>
-struct DynamicConverter<T,
-    typename std::enable_if<std::is_integral<T>::value &&
-                            !std::is_same<T, bool>::value>::type> {
+struct DynamicConverter<
+    T,
+    typename std::enable_if<
+        std::is_integral<T>::value && !std::is_same<T, bool>::value>::type> {
+  static T convert(const dynamic& d) {
+    return folly::to<T>(d.asInt());
+  }
+};
+
+// enums
+template <typename T>
+struct DynamicConverter<
+    T,
+    typename std::enable_if<std::is_enum<T>::value>::type> {
   static T convert(const dynamic& d) {
-    return static_cast<T>(d.asInt());
+    using type = typename std::underlying_type<T>::type;
+    return static_cast<T>(DynamicConverter<type>::convert(d));
   }
 };
 
 // floating point
 template <typename T>
-struct DynamicConverter<T,
+struct DynamicConverter<
+    T,
     typename std::enable_if<std::is_floating_point<T>::value>::type> {
   static T convert(const dynamic& d) {
-    return static_cast<T>(d.asDouble());
+    return folly::to<T>(d.asDouble());
   }
 };
 
@@ -206,13 +229,13 @@ struct DynamicConverter<folly::fbstring> {
 template <>
 struct DynamicConverter<std::string> {
   static std::string convert(const dynamic& d) {
-    return d.asString().toStdString();
+    return d.asString();
   }
 };
 
 // std::pair
 template <typename F, typename S>
-struct DynamicConverter<std::pair<F,S>> {
+struct DynamicConverter<std::pair<F, S>> {
   static std::pair<F, S> convert(const dynamic& d) {
     if (d.isArray() && d.size() == 2) {
       return std::make_pair(convertTo<F>(d[0]), convertTo<S>(d[1]));
@@ -225,53 +248,135 @@ struct DynamicConverter<std::pair<F,S>> {
   }
 };
 
-// map containers
+// non-associative containers
 template <typename C>
-struct DynamicConverter<C,
+struct DynamicConverter<
+    C,
     typename std::enable_if<
-      dynamicconverter_detail::is_map_container<C>::value>::type> {
+        dynamicconverter_detail::is_container<C>::value &&
+        !dynamicconverter_detail::is_associative<C>::value>::type> {
   static C convert(const dynamic& d) {
-    if (LIKELY(d.isObject())) {
+    if (d.isArray()) {
+      return C(dynamicconverter_detail::conversionIterator<C>(d.begin()),
+               dynamicconverter_detail::conversionIterator<C>(d.end()));
+    } else if (d.isObject()) {
       return C(dynamicconverter_detail::conversionIterator<C>
                  (d.items().begin()),
                dynamicconverter_detail::conversionIterator<C>
                  (d.items().end()));
-    } else if (d.isArray()) {
-      return C(dynamicconverter_detail::conversionIterator<C>(d.begin()),
-               dynamicconverter_detail::conversionIterator<C>(d.end()));
     } else {
       throw TypeError("object or array", d.type());
     }
   }
 };
 
-// non-map containers
+// associative containers
 template <typename C>
-struct DynamicConverter<C,
-      typename std::enable_if<
-          dynamicconverter_detail::is_container<C>::value &&
-          !dynamicconverter_detail::is_map_container<C>::value
-        >::type
-    > {
+struct DynamicConverter<
+    C,
+    typename std::enable_if<
+        dynamicconverter_detail::is_container<C>::value &&
+        dynamicconverter_detail::is_associative<C>::value>::type> {
   static C convert(const dynamic& d) {
-    if (LIKELY(d.isArray())) {
-      return C(dynamicconverter_detail::conversionIterator<C>(d.begin()),
-               dynamicconverter_detail::conversionIterator<C>(d.end()));
+    C ret; // avoid direct initialization due to unordered_map's constructor
+           // causing memory corruption if the iterator throws an exception
+    if (d.isArray()) {
+      ret.insert(
+          dynamicconverter_detail::conversionIterator<C>(d.begin()),
+          dynamicconverter_detail::conversionIterator<C>(d.end()));
+    } else if (d.isObject()) {
+      ret.insert(
+          dynamicconverter_detail::conversionIterator<C>(d.items().begin()),
+          dynamicconverter_detail::conversionIterator<C>(d.items().end()));
     } else {
-      throw TypeError("array", d.type());
+      throw TypeError("object or array", d.type());
+    }
+    return ret;
+  }
+};
+
+///////////////////////////////////////////////////////////////////////////////
+// DynamicConstructor specializations
+
+/**
+ * Each specialization of DynamicConstructor has the function
+ *     'static dynamic construct(const C&);'
+ */
+
+// default
+template <typename C, typename Enable = void>
+struct DynamicConstructor {
+  static dynamic construct(const C& x) {
+    return dynamic(x);
+  }
+};
+
+// identity
+template <typename C>
+struct DynamicConstructor<
+    C,
+    typename std::enable_if<std::is_same<C, dynamic>::value>::type> {
+  static dynamic construct(const C& x) {
+    return x;
+  }
+};
+
+// maps
+template <typename C>
+struct DynamicConstructor<
+    C,
+    typename std::enable_if<
+        !std::is_same<C, dynamic>::value &&
+        dynamicconverter_detail::is_map<C>::value>::type> {
+  static dynamic construct(const C& x) {
+    dynamic d = dynamic::object;
+    for (const auto& pair : x) {
+      d.insert(toDynamic(pair.first), toDynamic(pair.second));
+    }
+    return d;
+  }
+};
+
+// other ranges
+template <typename C>
+struct DynamicConstructor<
+    C,
+    typename std::enable_if<
+        !std::is_same<C, dynamic>::value &&
+        !dynamicconverter_detail::is_map<C>::value &&
+        !std::is_constructible<StringPiece, const C&>::value &&
+        dynamicconverter_detail::is_range<C>::value>::type> {
+  static dynamic construct(const C& x) {
+    dynamic d = dynamic::array;
+    for (const auto& item : x) {
+      d.push_back(toDynamic(item));
     }
+    return d;
+  }
+};
+
+// pair
+template <typename A, typename B>
+struct DynamicConstructor<std::pair<A, B>, void> {
+  static dynamic construct(const std::pair<A, B>& x) {
+    dynamic d = dynamic::array;
+    d.push_back(toDynamic(x.first));
+    d.push_back(toDynamic(x.second));
+    return d;
   }
 };
 
 ///////////////////////////////////////////////////////////////////////////////
-// convertTo implementation
+// implementation
 
 template <typename T>
 T convertTo(const dynamic& d) {
   return DynamicConverter<typename std::remove_cv<T>::type>::convert(d);
 }
 
-} // namespace folly
-
-#endif // DYNAMIC_CONVERTER_H
+template <typename T>
+dynamic toDynamic(const T& x) {
+  return DynamicConstructor<typename std::remove_cv<T>::type>::construct(x);
+}
 
+} // namespace folly