From b77b203935ec8f76ac6556222e066b23a127d81b Mon Sep 17 00:00:00 2001
From: Benoit Blanchon <github@benoitblanchon.fr>
Date: Fri, 7 Dec 2018 09:16:58 +0100
Subject: [PATCH] Extracted VariantData and CollectionData classes

---
 CHANGELOG.md                                  |   1 +
 src/ArduinoJson.hpp                           |   1 +
 src/ArduinoJson/Array/ArrayFunctions.hpp      |  90 +---
 src/ArduinoJson/Array/ArrayIterator.hpp       |  25 +-
 src/ArduinoJson/Array/ArrayRef.hpp            |  65 ++-
 src/ArduinoJson/Collection/CollectionData.hpp |  68 +++
 src/ArduinoJson/Collection/CollectionImpl.hpp | 145 +++++++
 .../Deserialization/deserialize.hpp           |  53 ++-
 src/ArduinoJson/Document/JsonDocument.hpp     |  33 +-
 src/ArduinoJson/Json/JsonDeserializer.hpp     |  63 ++-
 src/ArduinoJson/Json/JsonSerializer.hpp       |  30 +-
 src/ArduinoJson/Memory/MemoryPool.hpp         |   1 -
 src/ArduinoJson/Memory/StringBuilder.hpp      |   5 +-
 .../MsgPack/MsgPackDeserializer.hpp           | 105 +++--
 src/ArduinoJson/MsgPack/MsgPackSerializer.hpp |  17 +-
 src/ArduinoJson/Object/Key.hpp                |   2 +-
 src/ArduinoJson/Object/ObjectFunctions.hpp    | 122 ++----
 src/ArduinoJson/Object/ObjectIterator.hpp     |  21 +-
 src/ArduinoJson/Object/ObjectRef.hpp          |  78 ++--
 src/ArduinoJson/Object/Pair.hpp               |   8 +-
 .../Polyfills/type_traits/is_array.hpp        |   2 +
 .../StringStorage/StringCopier.hpp            |   6 +-
 src/ArduinoJson/StringStorage/StringMover.hpp |   6 +-
 src/ArduinoJson/Strings/ArduinoString.hpp     |   4 +-
 .../Strings/FixedSizeFlashString.hpp          |   4 +-
 .../Strings/FixedSizeRamString.hpp            |   5 +-
 src/ArduinoJson/Strings/StlString.hpp         |   4 +-
 .../Strings/StringInMemoryPool.hpp            |  39 --
 src/ArduinoJson/Strings/StringTypes.hpp       |   2 +-
 .../Strings/ZeroTerminatedFlashString.hpp     |   4 +-
 .../Strings/ZeroTerminatedRamString.hpp       |   5 +-
 src/ArduinoJson/Variant/SlotFunctions.hpp     |  17 +-
 src/ArduinoJson/Variant/VariantAs.hpp         |   9 +-
 src/ArduinoJson/Variant/VariantAsImpl.hpp     |   3 +-
 src/ArduinoJson/Variant/VariantContent.hpp    |  46 +++
 src/ArduinoJson/Variant/VariantData.hpp       | 343 +++++++++++++---
 src/ArduinoJson/Variant/VariantFunctions.hpp  | 386 ++++++------------
 src/ArduinoJson/Variant/VariantImpl.hpp       | 103 ++---
 src/ArduinoJson/Variant/VariantRef.hpp        |  47 +--
 src/ArduinoJson/Variant/VariantSlot.hpp       |  54 ++-
 test/JsonArray/equals.cpp                     |  20 +-
 test/JsonObject/equals.cpp                    |  20 +-
 test/MemoryPool/StringBuilder.cpp             |  18 +-
 test/MemoryPool/clear.cpp                     |  16 +-
 test/MemoryPool/size.cpp                      |  40 +-
 45 files changed, 1129 insertions(+), 1007 deletions(-)
 create mode 100644 src/ArduinoJson/Collection/CollectionData.hpp
 create mode 100644 src/ArduinoJson/Collection/CollectionImpl.hpp
 delete mode 100644 src/ArduinoJson/Strings/StringInMemoryPool.hpp
 create mode 100644 src/ArduinoJson/Variant/VariantContent.hpp

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4c17f2bd..a6a9062f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ HEAD
 * Removed the automatic expansion of `DynamicJsonDocument`, it now has a fixed capacity.
 * Restored the monotonic allocator because the code was getting too big
 * Reduced the memory usage
+* Reduced the code size
 * Removed spurious files in the Particle library
 
 v6.6.0-beta (2018-11-13)
diff --git a/src/ArduinoJson.hpp b/src/ArduinoJson.hpp
index 07c1565a..70d1bd9f 100644
--- a/src/ArduinoJson.hpp
+++ b/src/ArduinoJson.hpp
@@ -15,6 +15,7 @@
 
 #include "ArduinoJson/Array/ArrayImpl.hpp"
 #include "ArduinoJson/Array/ArraySubscript.hpp"
+#include "ArduinoJson/Collection/CollectionImpl.hpp"
 #include "ArduinoJson/Object/ObjectImpl.hpp"
 #include "ArduinoJson/Object/ObjectSubscript.hpp"
 #include "ArduinoJson/Variant/VariantAsImpl.hpp"
diff --git a/src/ArduinoJson/Array/ArrayFunctions.hpp b/src/ArduinoJson/Array/ArrayFunctions.hpp
index 19652b45..f13984a6 100644
--- a/src/ArduinoJson/Array/ArrayFunctions.hpp
+++ b/src/ArduinoJson/Array/ArrayFunctions.hpp
@@ -4,92 +4,26 @@
 
 #pragma once
 
-#include "../Variant/SlotFunctions.hpp"
-#include "../Variant/VariantData.hpp"
+#include "../Collection/CollectionData.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
 
-inline VariantData* arrayAdd(ArrayData* arr, MemoryPool* pool) {
-  if (!arr) return 0;
-
-  VariantSlot* slot = pool->allocVariant();
-  if (!slot) return 0;
-
-  slot->init();
-
-  if (arr->tail) {
-    slot->attachTo(arr->tail);
-    arr->tail = slot;
-  } else {
-    arr->head = slot;
-    arr->tail = slot;
-  }
-
-  return slot->getData();
+inline VariantData *arrayAdd(CollectionData *arr, MemoryPool *pool) {
+  return arr ? arr->add(pool) : 0;
 }
 
-inline VariantSlot* arrayGetSlot(const ArrayData* arr, size_t index) {
-  if (!arr) return 0;
-  return arr->head->getNext(index);
-}
-
-inline VariantData* arrayGet(const ArrayData* arr, size_t index) {
-  VariantSlot* slot = arrayGetSlot(arr, index);
-  return slot ? slot->getData() : 0;
-}
-
-inline void arrayRemove(ArrayData* arr, VariantSlot* slot) {
-  if (!arr || !slot) return;
-
-  VariantSlot* prev = slot->getPrev(arr->head);
-  VariantSlot* next = slot->getNext();
-
-  if (prev)
-    prev->setNext(next);
+template <typename Visitor>
+inline void arrayAccept(const CollectionData *arr, Visitor &visitor) {
+  if (arr)
+    visitor.visitArray(*arr);
   else
-    arr->head = next;
-  if (!next) arr->tail = prev;
+    visitor.visitNull();
 }
 
-inline void arrayRemove(ArrayData* arr, size_t index) {
-  arrayRemove(arr, arrayGetSlot(arr, index));
-}
+inline bool arrayEquals(const CollectionData *lhs, const CollectionData *rhs) {
+  if (lhs == rhs) return true;
+  if (!lhs || !rhs) return false;
 
-inline void arrayClear(ArrayData* arr) {
-  if (!arr) return;
-  arr->head = 0;
-  arr->tail = 0;
-}
-
-bool variantCopy(VariantData*, const VariantData*, MemoryPool*);
-
-inline bool arrayCopy(ArrayData* dst, const ArrayData* src, MemoryPool* pool) {
-  if (!dst || !src) return false;
-  arrayClear(dst);
-  for (VariantSlot* s = src->head; s; s = s->getNext()) {
-    if (!variantCopy(arrayAdd(dst, pool), s->getData(), pool)) return false;
-  }
-  return true;
-}
-
-bool variantEquals(const VariantData*, const VariantData*);
-
-inline bool arrayEquals(const ArrayData* a1, const ArrayData* a2) {
-  if (a1 == a2) return true;
-  if (!a1 || !a2) return false;
-  VariantSlot* s1 = a1->head;
-  VariantSlot* s2 = a2->head;
-  for (;;) {
-    if (s1 == s2) return true;
-    if (!s1 || !s2) return false;
-    if (!variantEquals(s1->getData(), s2->getData())) return false;
-    s1 = s1->getNext();
-    s2 = s2->getNext();
-  }
-}
-
-inline size_t arraySize(const ArrayData* arr) {
-  if (!arr) return 0;
-  return slotSize(arr->head);
+  return lhs->equalsArray(*rhs);
 }
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Array/ArrayIterator.hpp b/src/ArduinoJson/Array/ArrayIterator.hpp
index 6bc88bbf..84b5bfb0 100644
--- a/src/ArduinoJson/Array/ArrayIterator.hpp
+++ b/src/ArduinoJson/Array/ArrayIterator.hpp
@@ -11,8 +11,7 @@ namespace ARDUINOJSON_NAMESPACE {
 
 class VariantPtr {
  public:
-  VariantPtr(MemoryPool *memoryPool, VariantData *data)
-      : _variant(memoryPool, data) {}
+  VariantPtr(MemoryPool *pool, VariantData *data) : _variant(pool, data) {}
 
   VariantRef *operator->() {
     return &_variant;
@@ -29,14 +28,14 @@ class VariantPtr {
 class ArrayIterator {
  public:
   ArrayIterator() : _slot(0) {}
-  explicit ArrayIterator(MemoryPool *memoryPool, VariantSlot *slot)
-      : _memoryPool(memoryPool), _slot(slot) {}
+  explicit ArrayIterator(MemoryPool *pool, VariantSlot *slot)
+      : _pool(pool), _slot(slot) {}
 
   VariantRef operator*() const {
-    return VariantRef(_memoryPool, _slot->getData());
+    return VariantRef(_pool, _slot->data());
   }
   VariantPtr operator->() {
-    return VariantPtr(_memoryPool, _slot->getData());
+    return VariantPtr(_pool, _slot->data());
   }
 
   bool operator==(const ArrayIterator &other) const {
@@ -48,12 +47,12 @@ class ArrayIterator {
   }
 
   ArrayIterator &operator++() {
-    _slot = _slot->getNext();
+    _slot = _slot->next();
     return *this;
   }
 
   ArrayIterator &operator+=(size_t distance) {
-    _slot = _slot->getNext(distance);
+    _slot = _slot->next(distance);
     return *this;
   }
 
@@ -62,7 +61,7 @@ class ArrayIterator {
   }
 
  private:
-  MemoryPool *_memoryPool;
+  MemoryPool *_pool;
   VariantSlot *_slot;
 };
 
@@ -88,10 +87,10 @@ class ArrayConstRefIterator {
   explicit ArrayConstRefIterator(const VariantSlot *slot) : _slot(slot) {}
 
   VariantConstRef operator*() const {
-    return VariantConstRef(_slot->getData());
+    return VariantConstRef(_slot->data());
   }
   VariantConstPtr operator->() {
-    return VariantConstPtr(_slot->getData());
+    return VariantConstPtr(_slot->data());
   }
 
   bool operator==(const ArrayConstRefIterator &other) const {
@@ -103,12 +102,12 @@ class ArrayConstRefIterator {
   }
 
   ArrayConstRefIterator &operator++() {
-    _slot = _slot->getNext();
+    _slot = _slot->next();
     return *this;
   }
 
   ArrayConstRefIterator &operator+=(size_t distance) {
-    _slot = _slot->getNext(distance);
+    _slot = _slot->next(distance);
     return *this;
   }
 
diff --git a/src/ArduinoJson/Array/ArrayRef.hpp b/src/ArduinoJson/Array/ArrayRef.hpp
index 2fc6695c..23059ffb 100644
--- a/src/ArduinoJson/Array/ArrayRef.hpp
+++ b/src/ArduinoJson/Array/ArrayRef.hpp
@@ -21,16 +21,21 @@ class ArraySubscript;
 template <typename TData>
 class ArrayRefBase {
  public:
+  template <typename Visitor>
+  FORCE_INLINE void accept(Visitor& visitor) const {
+    arrayAccept(_data, visitor);
+  }
+
   FORCE_INLINE bool isNull() const {
     return _data == 0;
   }
 
   FORCE_INLINE VariantConstRef operator[](size_t index) const {
-    return VariantConstRef(arrayGet(_data, index));
+    return VariantConstRef(_data ? _data->get(index) : 0);
   }
 
   FORCE_INLINE size_t size() const {
-    return arraySize(_data);
+    return _data ? _data->size() : 0;
   }
 
  protected:
@@ -38,24 +43,17 @@ class ArrayRefBase {
   TData* _data;
 };
 
-class ArrayConstRef : public ArrayRefBase<const ArrayData>, public Visitable {
+class ArrayConstRef : public ArrayRefBase<const CollectionData>,
+                      public Visitable {
   friend class ArrayRef;
-  typedef ArrayRefBase<const ArrayData> base_type;
+  typedef ArrayRefBase<const CollectionData> base_type;
 
  public:
   typedef ArrayConstRefIterator iterator;
 
-  template <typename Visitor>
-  FORCE_INLINE void accept(Visitor& visitor) const {
-    if (_data)
-      visitor.visitArray(*this);
-    else
-      visitor.visitNull();
-  }
-
   FORCE_INLINE iterator begin() const {
     if (!_data) return iterator();
-    return iterator(_data->head);
+    return iterator(_data->head());
   }
 
   FORCE_INLINE iterator end() const {
@@ -63,25 +61,25 @@ class ArrayConstRef : public ArrayRefBase<const ArrayData>, public Visitable {
   }
 
   FORCE_INLINE ArrayConstRef() : base_type(0) {}
-  FORCE_INLINE ArrayConstRef(const ArrayData* data) : base_type(data) {}
+  FORCE_INLINE ArrayConstRef(const CollectionData* data) : base_type(data) {}
 
   FORCE_INLINE bool operator==(ArrayConstRef rhs) const {
     return arrayEquals(_data, rhs._data);
   }
 };
 
-class ArrayRef : public ArrayRefBase<ArrayData>, public Visitable {
-  typedef ArrayRefBase<ArrayData> base_type;
+class ArrayRef : public ArrayRefBase<CollectionData>, public Visitable {
+  typedef ArrayRefBase<CollectionData> base_type;
 
  public:
   typedef ArrayIterator iterator;
 
-  FORCE_INLINE ArrayRef() : base_type(0), _memoryPool(0) {}
-  FORCE_INLINE ArrayRef(MemoryPool* pool, ArrayData* data)
-      : base_type(data), _memoryPool(pool) {}
+  FORCE_INLINE ArrayRef() : base_type(0), _pool(0) {}
+  FORCE_INLINE ArrayRef(MemoryPool* pool, CollectionData* data)
+      : base_type(data), _pool(pool) {}
 
   operator VariantRef() {
-    return VariantRef(_memoryPool, getVariantData(_data));
+    return VariantRef(_pool, reinterpret_cast<VariantData*>(_data));
   }
 
   operator ArrayConstRef() const {
@@ -110,12 +108,12 @@ class ArrayRef : public ArrayRefBase<ArrayData>, public Visitable {
   }
 
   VariantRef add() const {
-    return VariantRef(_memoryPool, arrayAdd(_data, _memoryPool));
+    return VariantRef(_pool, arrayAdd(_data, _pool));
   }
 
   FORCE_INLINE iterator begin() const {
     if (!_data) return iterator();
-    return iterator(_memoryPool, _data->head);
+    return iterator(_pool, _data->head());
   }
 
   FORCE_INLINE iterator end() const {
@@ -153,7 +151,8 @@ class ArrayRef : public ArrayRefBase<ArrayData>, public Visitable {
 
   // Copy a ArrayRef
   FORCE_INLINE bool copyFrom(ArrayRef src) const {
-    return arrayCopy(_data, src._data, _memoryPool);
+    if (!_data || !src._data) return false;
+    return _data->copyFrom(*src._data, _pool);
   }
 
   // Exports a 1D array
@@ -191,30 +190,22 @@ class ArrayRef : public ArrayRefBase<ArrayData>, public Visitable {
 
   // Gets the value at the specified index.
   FORCE_INLINE VariantRef get(size_t index) const {
-    return VariantRef(_memoryPool, arrayGet(_data, index));
+    return VariantRef(_pool, _data ? _data->get(index) : 0);
   }
 
   // Removes element at specified position.
   FORCE_INLINE void remove(iterator it) const {
-    arrayRemove(_data, it.internal());
+    if (!_data) return;
+    _data->remove(it.internal());
   }
 
   // Removes element at specified index.
   FORCE_INLINE void remove(size_t index) const {
-    arrayRemove(_data, index);
-  }
-
-  template <typename Visitor>
-  FORCE_INLINE void accept(Visitor& visitor) const {
-    ArrayConstRef(_data).accept(visitor);
+    if (!_data) return;
+    _data->remove(index);
   }
 
  private:
-  template <typename TValueRef>
-  FORCE_INLINE bool add_impl(TValueRef value) const {
-    return add().set(value);
-  }
-
-  MemoryPool* _memoryPool;
+  MemoryPool* _pool;
 };
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Collection/CollectionData.hpp b/src/ArduinoJson/Collection/CollectionData.hpp
new file mode 100644
index 00000000..54bd12b8
--- /dev/null
+++ b/src/ArduinoJson/Collection/CollectionData.hpp
@@ -0,0 +1,68 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2018
+// MIT License
+
+#pragma once
+
+namespace ARDUINOJSON_NAMESPACE {
+
+class MemoryPool;
+class VariantData;
+class VariantSlot;
+
+class CollectionData {
+  VariantSlot *_head;
+  VariantSlot *_tail;
+
+ public:
+  // Must be a POD!
+  // - no constructor
+  // - no destructor
+  // - no virtual
+  // - no inheritance
+  VariantSlot *addSlot(MemoryPool *);
+
+  VariantData *add(MemoryPool *pool);
+
+  template <typename TKey>
+  VariantData *add(TKey key, MemoryPool *pool);
+
+  void clear();
+
+  template <typename TKey>
+  bool containsKey(const TKey &key) const;
+
+  bool copyFrom(const CollectionData &src, MemoryPool *pool);
+
+  bool equalsArray(const CollectionData &other) const;
+  bool equalsObject(const CollectionData &other) const;
+
+  VariantData *get(size_t index) const;
+
+  template <typename TKey>
+  VariantData *get(TKey key) const;
+
+  VariantSlot *head() const {
+    return _head;
+  }
+
+  void remove(size_t index);
+
+  template <typename TKey>
+  void remove(TKey key) {
+    remove(getSlot(key));
+  }
+
+  void remove(VariantSlot *slot);
+
+  size_t size() const;
+
+ private:
+  VariantSlot *getSlot(size_t index) const;
+
+  template <typename TKey>
+  VariantSlot *getSlot(TKey key) const;
+
+  VariantSlot *getPreviousSlot(VariantSlot *) const;
+};
+}  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Collection/CollectionImpl.hpp b/src/ArduinoJson/Collection/CollectionImpl.hpp
new file mode 100644
index 00000000..45683a52
--- /dev/null
+++ b/src/ArduinoJson/Collection/CollectionImpl.hpp
@@ -0,0 +1,145 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2018
+// MIT License
+
+#pragma once
+
+#include "../Variant/VariantData.hpp"
+#include "CollectionData.hpp"
+
+namespace ARDUINOJSON_NAMESPACE {
+
+inline VariantSlot* CollectionData::addSlot(MemoryPool* pool) {
+  VariantSlot* slot = pool->allocVariant();
+  if (!slot) return 0;
+
+  if (_tail) {
+    _tail->setNextNotNull(slot);
+    _tail = slot;
+  } else {
+    _head = slot;
+    _tail = slot;
+  }
+
+  slot->clear();
+  return slot;
+}
+
+inline VariantData* CollectionData::add(MemoryPool* pool) {
+  return addSlot(pool)->data();
+}
+
+template <typename TKey>
+inline VariantData* CollectionData::add(TKey key, MemoryPool* pool) {
+  VariantSlot* slot = addSlot(pool);
+  if (!slotSetKey(slot, key, pool)) return 0;
+  return slot->data();
+}
+
+inline void CollectionData::clear() {
+  _head = 0;
+  _tail = 0;
+}
+
+template <typename TKey>
+inline bool CollectionData::containsKey(const TKey& key) const {
+  return getSlot(key) != 0;
+}
+
+inline bool CollectionData::copyFrom(const CollectionData& src,
+                                     MemoryPool* pool) {
+  clear();
+  for (VariantSlot* s = src._head; s; s = s->next()) {
+    VariantData* var;
+    if (s->key() != 0) {
+      if (s->ownsKey())
+        var = add(ZeroTerminatedRamString(s->key()), pool);
+      else
+        var = add(ZeroTerminatedRamStringConst(s->key()), pool);
+    } else {
+      var = add(pool);
+    }
+    if (!var) return false;
+    if (!var->copyFrom(*s->data(), pool)) return false;
+  }
+  return true;
+}
+
+inline bool CollectionData::equalsObject(const CollectionData& other) const {
+  size_t count = 0;
+  for (VariantSlot* slot = _head; slot; slot = slot->next()) {
+    VariantData* v1 = slot->data();
+    VariantData* v2 = other.get(makeString(slot->key()));
+    if (!variantEquals(v1, v2)) return false;
+    count++;
+  }
+  return count == other.size();
+}
+
+inline bool CollectionData::equalsArray(const CollectionData& other) const {
+  VariantSlot* s1 = _head;
+  VariantSlot* s2 = other._head;
+  for (;;) {
+    if (s1 == s2) return true;
+    if (!s1 || !s2) return false;
+    if (!variantEquals(s1->data(), s2->data())) return false;
+    s1 = s1->next();
+    s2 = s2->next();
+  }
+}
+
+template <typename TKey>
+inline VariantSlot* CollectionData::getSlot(TKey key) const {
+  VariantSlot* slot = _head;
+  while (slot) {
+    if (key.equals(slot->key())) break;
+    slot = slot->next();
+  }
+  return slot;
+}
+
+inline VariantSlot* CollectionData::getSlot(size_t index) const {
+  return _head->next(index);
+}
+
+inline VariantSlot* CollectionData::getPreviousSlot(VariantSlot* target) const {
+  VariantSlot* current = _head;
+  while (current) {
+    VariantSlot* next = current->next();
+    if (next == target) return current;
+    current = next;
+  }
+  return 0;
+}
+
+template <typename TKey>
+inline VariantData* CollectionData::get(TKey key) const {
+  VariantSlot* slot = getSlot(key);
+  return slot ? slot->data() : 0;
+}
+
+inline VariantData* CollectionData::get(size_t index) const {
+  VariantSlot* slot = getSlot(index);
+  return slot ? slot->data() : 0;
+}
+
+inline void CollectionData::remove(VariantSlot* slot) {
+  if (!slot) return;
+  VariantSlot* prev = getPreviousSlot(slot);
+  VariantSlot* next = slot->next();
+  if (prev)
+    prev->setNext(next);
+  else
+    _head = next;
+  if (!next) _tail = prev;
+}
+
+inline void CollectionData::remove(size_t index) {
+  remove(getSlot(index));
+}
+
+inline size_t CollectionData::size() const {
+  return slotSize(_head);
+}
+
+}  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Deserialization/deserialize.hpp b/src/ArduinoJson/Deserialization/deserialize.hpp
index d2d16da5..bf686997 100644
--- a/src/ArduinoJson/Deserialization/deserialize.hpp
+++ b/src/ArduinoJson/Deserialization/deserialize.hpp
@@ -14,63 +14,58 @@
 
 namespace ARDUINOJSON_NAMESPACE {
 
-template <template <typename, typename> class TDeserializer,
-          typename TMemoryPool, typename TReader, typename TWriter>
-TDeserializer<TReader, TWriter> makeDeserializer(TMemoryPool &memoryPool,
+template <template <typename, typename> class TDeserializer, typename TReader,
+          typename TWriter>
+TDeserializer<TReader, TWriter> makeDeserializer(MemoryPool &pool,
                                                  TReader reader, TWriter writer,
                                                  uint8_t nestingLimit) {
-  return TDeserializer<TReader, TWriter>(memoryPool, reader, writer,
-                                         nestingLimit);
+  return TDeserializer<TReader, TWriter>(pool, reader, writer, nestingLimit);
 }
 
-// DeserializationError deserialize(TDocument& doc, TString input);
-// TDocument = DynamicJsonDocument, StaticJsonDocument
+// DeserializationError deserialize(JsonDocument& doc, TString input);
 // TString = const std::string&, const String&
-template <template <typename, typename> class TDeserializer, typename TDocument,
-          typename TString>
+template <template <typename, typename> class TDeserializer, typename TString>
 typename enable_if<!is_array<TString>::value, DeserializationError>::type
-deserialize(TDocument &doc, const TString &input) {
+deserialize(JsonDocument &doc, const TString &input) {
+  doc.clear();
   return makeDeserializer<TDeserializer>(
              doc.memoryPool(), makeReader(input),
              makeStringStorage(doc.memoryPool(), input), doc.nestingLimit)
-      .parse(doc.template to<VariantRef>());
+      .parse(doc.data());
 }
 //
-// DeserializationError deserialize(TDocument& doc, TChar* input);
-// TDocument = DynamicJsonDocument, StaticJsonDocument
+// DeserializationError deserialize(JsonDocument& doc, TChar* input);
 // TChar* = char*, const char*, const FlashStringHelper*
-template <template <typename, typename> class TDeserializer, typename TDocument,
-          typename TChar>
-DeserializationError deserialize(TDocument &doc, TChar *input) {
+template <template <typename, typename> class TDeserializer, typename TChar>
+DeserializationError deserialize(JsonDocument &doc, TChar *input) {
+  doc.clear();
   return makeDeserializer<TDeserializer>(
              doc.memoryPool(), makeReader(input),
              makeStringStorage(doc.memoryPool(), input), doc.nestingLimit)
-      .parse(doc.template to<VariantRef>());
+      .parse(doc.data());
 }
 //
-// DeserializationError deserialize(TDocument& doc, TChar* input, size_t
+// DeserializationError deserialize(JsonDocument& doc, TChar* input, size_t
 // inputSize);
-// TDocument = DynamicJsonDocument, StaticJsonDocument
 // TChar* = char*, const char*, const FlashStringHelper*
-template <template <typename, typename> class TDeserializer, typename TDocument,
-          typename TChar>
-DeserializationError deserialize(TDocument &doc, TChar *input,
+template <template <typename, typename> class TDeserializer, typename TChar>
+DeserializationError deserialize(JsonDocument &doc, TChar *input,
                                  size_t inputSize) {
+  doc.clear();
   return makeDeserializer<TDeserializer>(
              doc.memoryPool(), makeReader(input, inputSize),
              makeStringStorage(doc.memoryPool(), input), doc.nestingLimit)
-      .parse(doc.template to<VariantRef>());
+      .parse(doc.data());
 }
 //
-// DeserializationError deserialize(TDocument& doc, TStream input);
-// TDocument = DynamicJsonDocument, StaticJsonDocument
+// DeserializationError deserialize(JsonDocument& doc, TStream input);
 // TStream = std::istream&, Stream&
-template <template <typename, typename> class TDeserializer, typename TDocument,
-          typename TStream>
-DeserializationError deserialize(TDocument &doc, TStream &input) {
+template <template <typename, typename> class TDeserializer, typename TStream>
+DeserializationError deserialize(JsonDocument &doc, TStream &input) {
+  doc.clear();
   return makeDeserializer<TDeserializer>(
              doc.memoryPool(), makeReader(input),
              makeStringStorage(doc.memoryPool(), input), doc.nestingLimit)
-      .parse(doc.template to<VariantRef>());
+      .parse(doc.data());
 }
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Document/JsonDocument.hpp b/src/ArduinoJson/Document/JsonDocument.hpp
index 8e003156..efec5393 100644
--- a/src/ArduinoJson/Document/JsonDocument.hpp
+++ b/src/ArduinoJson/Document/JsonDocument.hpp
@@ -30,8 +30,8 @@ class JsonDocument : public Visitable {
   }
 
   void clear() {
-    _memoryPool.clear();
-    _rootData.type = JSON_NULL;
+    _pool.clear();
+    _data.setNull();
   }
 
   template <typename T>
@@ -40,16 +40,11 @@ class JsonDocument : public Visitable {
   }
 
   size_t memoryUsage() const {
-    return _memoryPool.size();
+    return _pool.size();
   }
 
   size_t capacity() const {
-    return _memoryPool.capacity();
-  }
-
-  // for internal use only
-  MemoryPool& memoryPool() {
-    return _memoryPool;
+    return _pool.capacity();
   }
 
   template <typename T>
@@ -58,10 +53,18 @@ class JsonDocument : public Visitable {
     return getVariant().template to<T>();
   }
 
+  // for internal use only
+  MemoryPool& memoryPool() {
+    return _pool;
+  }
+
+  VariantData& data() {
+    return _data;
+  }
+
  protected:
   JsonDocument(char* buf, size_t capa)
-      : nestingLimit(ARDUINOJSON_DEFAULT_NESTING_LIMIT),
-        _memoryPool(buf, capa) {}
+      : nestingLimit(ARDUINOJSON_DEFAULT_NESTING_LIMIT), _pool(buf, capa) {}
 
   void copy(const JsonDocument& src) {
     nestingLimit = src.nestingLimit;
@@ -70,15 +73,15 @@ class JsonDocument : public Visitable {
 
  private:
   VariantRef getVariant() {
-    return VariantRef(&_memoryPool, &_rootData);
+    return VariantRef(&_pool, &_data);
   }
 
   VariantConstRef getVariant() const {
-    return VariantConstRef(&_rootData);
+    return VariantConstRef(&_data);
   }
 
-  MemoryPool _memoryPool;
-  VariantData _rootData;
+  MemoryPool _pool;
+  VariantData _data;
 };
 
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Json/JsonDeserializer.hpp b/src/ArduinoJson/Json/JsonDeserializer.hpp
index a1d14956..e69e43ca 100644
--- a/src/ArduinoJson/Json/JsonDeserializer.hpp
+++ b/src/ArduinoJson/Json/JsonDeserializer.hpp
@@ -9,7 +9,7 @@
 #include "../Numbers/isFloat.hpp"
 #include "../Numbers/isInteger.hpp"
 #include "../Polyfills/type_traits.hpp"
-#include "../Variant/VariantRef.hpp"
+#include "../Variant/VariantData.hpp"
 #include "EscapeSequence.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
@@ -18,26 +18,26 @@ template <typename TReader, typename TStringStorage>
 class JsonDeserializer {
   typedef typename remove_reference<TStringStorage>::type::StringBuilder
       StringBuilder;
-  typedef typename StringBuilder::StringType StringType;
+  typedef const char *StringType;
 
  public:
-  JsonDeserializer(MemoryPool &memoryPool, TReader reader,
+  JsonDeserializer(MemoryPool &pool, TReader reader,
                    TStringStorage stringStorage, uint8_t nestingLimit)
-      : _memoryPool(&memoryPool),
+      : _pool(&pool),
         _reader(reader),
         _stringStorage(stringStorage),
         _nestingLimit(nestingLimit),
         _loaded(false) {}
-  DeserializationError parse(VariantRef variant) {
+  DeserializationError parse(VariantData &variant) {
     DeserializationError err = skipSpacesAndComments();
     if (err) return err;
 
     switch (current()) {
       case '[':
-        return parseArray(variant);
+        return parseArray(variant.toArray());
 
       case '{':
-        return parseObject(variant);
+        return parseObject(variant.toObject());
 
       default:
         return parseValue(variant);
@@ -68,12 +68,9 @@ class JsonDeserializer {
     return true;
   }
 
-  DeserializationError parseArray(VariantRef variant) {
+  DeserializationError parseArray(CollectionData &array) {
     if (_nestingLimit == 0) return DeserializationError::TooDeep;
 
-    ArrayRef array = variant.to<ArrayRef>();
-    if (array.isNull()) return DeserializationError::NoMemory;
-
     // Check opening braket
     if (!eat('[')) return DeserializationError::InvalidInput;
 
@@ -87,12 +84,12 @@ class JsonDeserializer {
     // Read each value
     for (;;) {
       // Allocate slot in array
-      VariantRef value = array.add();
-      if (value.isInvalid()) return DeserializationError::NoMemory;
+      VariantData *value = array.add(_pool);
+      if (!value) return DeserializationError::NoMemory;
 
       // 1 - Parse value
       _nestingLimit--;
-      err = parse(value);
+      err = parse(*value);
       _nestingLimit++;
       if (err) return err;
 
@@ -106,12 +103,9 @@ class JsonDeserializer {
     }
   }
 
-  DeserializationError parseObject(VariantRef variant) {
+  DeserializationError parseObject(CollectionData &object) {
     if (_nestingLimit == 0) return DeserializationError::TooDeep;
 
-    ObjectRef object = variant.to<ObjectRef>();
-    if (object.isNull()) return DeserializationError::NoMemory;
-
     // Check opening brace
     if (!eat('{')) return DeserializationError::InvalidInput;
 
@@ -124,23 +118,24 @@ class JsonDeserializer {
 
     // Read each key value pair
     for (;;) {
+      // Allocate slot in object
+      VariantSlot *slot = object.addSlot(_pool);
+      if (!slot) return DeserializationError::NoMemory;
+
       // Parse key
       StringType key;
       err = parseKey(key);
       if (err) return err;
+      slot->setOwnedKey(key);
 
       // Skip spaces
       err = skipSpacesAndComments();
       if (err) return err;  // Colon
       if (!eat(':')) return DeserializationError::InvalidInput;
 
-      // Allocate slot in object
-      VariantRef value = object.set(key);
-      if (value.isInvalid()) return DeserializationError::NoMemory;
-
       // Parse value
       _nestingLimit--;
-      err = parse(value);
+      err = parse(*slot->data());
       _nestingLimit++;
       if (err) return err;
 
@@ -158,7 +153,7 @@ class JsonDeserializer {
     }
   }
 
-  DeserializationError parseValue(VariantRef variant) {
+  DeserializationError parseValue(VariantData &variant) {
     if (isQuote(current())) {
       return parseStringValue(variant);
     } else {
@@ -174,11 +169,11 @@ class JsonDeserializer {
     }
   }
 
-  DeserializationError parseStringValue(VariantRef variant) {
+  DeserializationError parseStringValue(VariantData &variant) {
     StringType value;
     DeserializationError err = parseQuotedString(value);
     if (err) return err;
-    variant.set(value);
+    variant.setOwnedString(value);
     return DeserializationError::Ok;
   }
 
@@ -208,7 +203,7 @@ class JsonDeserializer {
     }
 
     result = builder.complete();
-    if (result.isNull()) return DeserializationError::NoMemory;
+    if (!result) return DeserializationError::NoMemory;
     return DeserializationError::Ok;
   }
 
@@ -229,11 +224,11 @@ class JsonDeserializer {
     }
 
     result = builder.complete();
-    if (result.isNull()) return DeserializationError::NoMemory;
+    if (!result) return DeserializationError::NoMemory;
     return DeserializationError::Ok;
   }
 
-  DeserializationError parseNumericValue(VariantRef result) {
+  DeserializationError parseNumericValue(VariantData &result) {
     char buffer[64];
     uint8_t n = 0;
 
@@ -246,13 +241,13 @@ class JsonDeserializer {
     buffer[n] = 0;
 
     if (isInteger(buffer)) {
-      result.set(parseInteger<Integer>(buffer));
+      result.setInteger(parseInteger<Integer>(buffer));
     } else if (isFloat(buffer)) {
-      result.set(parseFloat<Float>(buffer));
+      result.setFloat(parseFloat<Float>(buffer));
     } else if (!strcmp(buffer, "true")) {
-      result.set(true);
+      result.setBoolean(true);
     } else if (!strcmp(buffer, "false")) {
-      result.set(false);
+      result.setBoolean(false);
     } else if (!strcmp(buffer, "null")) {
       // already null
     } else {
@@ -333,7 +328,7 @@ class JsonDeserializer {
     }
   }
 
-  MemoryPool *_memoryPool;
+  MemoryPool *_pool;
   TReader _reader;
   TStringStorage _stringStorage;
   uint8_t _nestingLimit;
diff --git a/src/ArduinoJson/Json/JsonSerializer.hpp b/src/ArduinoJson/Json/JsonSerializer.hpp
index 4b90957f..a959926c 100644
--- a/src/ArduinoJson/Json/JsonSerializer.hpp
+++ b/src/ArduinoJson/Json/JsonSerializer.hpp
@@ -20,15 +20,16 @@ class JsonSerializer {
     _writer.writeFloat(value);
   }
 
-  void visitArray(ArrayConstRef array) {
+  void visitArray(const CollectionData &array) {
     _writer.beginArray();
 
-    ArrayConstRef::iterator it = array.begin();
-    while (it != array.end()) {
-      it->accept(*this);
+    VariantSlot *slot = array.head();
 
-      ++it;
-      if (it == array.end()) break;
+    while (slot != 0) {
+      slot->data()->accept(*this);
+
+      slot = slot->next();
+      if (slot == 0) break;
 
       _writer.writeComma();
     }
@@ -36,17 +37,18 @@ class JsonSerializer {
     _writer.endArray();
   }
 
-  void visitObject(ObjectConstRef object) {
+  void visitObject(const CollectionData &object) {
     _writer.beginObject();
 
-    ObjectConstRef::iterator it = object.begin();
-    while (it != object.end()) {
-      _writer.writeString(it->key());
-      _writer.writeColon();
-      it->value().accept(*this);
+    VariantSlot *slot = object.head();
 
-      ++it;
-      if (it == object.end()) break;
+    while (slot != 0) {
+      _writer.writeString(slot->key());
+      _writer.writeColon();
+      slot->data()->accept(*this);
+
+      slot = slot->next();
+      if (slot == 0) break;
 
       _writer.writeComma();
     }
diff --git a/src/ArduinoJson/Memory/MemoryPool.hpp b/src/ArduinoJson/Memory/MemoryPool.hpp
index d894bc55..7bc09095 100644
--- a/src/ArduinoJson/Memory/MemoryPool.hpp
+++ b/src/ArduinoJson/Memory/MemoryPool.hpp
@@ -6,7 +6,6 @@
 
 #include "../Polyfills/assert.hpp"
 #include "../Polyfills/mpl/max.hpp"
-#include "../Strings/StringInMemoryPool.hpp"
 #include "../Variant/VariantSlot.hpp"
 #include "Alignment.hpp"
 #include "MemoryPool.hpp"
diff --git a/src/ArduinoJson/Memory/StringBuilder.hpp b/src/ArduinoJson/Memory/StringBuilder.hpp
index b37c8efe..14c94773 100644
--- a/src/ArduinoJson/Memory/StringBuilder.hpp
+++ b/src/ArduinoJson/Memory/StringBuilder.hpp
@@ -4,15 +4,12 @@
 
 #pragma once
 
-#include "../Strings/StringInMemoryPool.hpp"
 #include "MemoryPool.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
 
 class StringBuilder {
  public:
-  typedef StringInMemoryPool StringType;
-
   explicit StringBuilder(MemoryPool* parent) : _parent(parent), _size(0) {
     _slot = _parent->allocExpandableString();
   }
@@ -36,7 +33,7 @@ class StringBuilder {
     _slot.value[_size++] = c;
   }
 
-  StringType complete() {
+  char* complete() {
     append('\0');
     if (_slot.value) {
       _parent->freezeString(_slot, _size);
diff --git a/src/ArduinoJson/MsgPack/MsgPackDeserializer.hpp b/src/ArduinoJson/MsgPack/MsgPackDeserializer.hpp
index 7095259e..a2f6a51c 100644
--- a/src/ArduinoJson/MsgPack/MsgPackDeserializer.hpp
+++ b/src/ArduinoJson/MsgPack/MsgPackDeserializer.hpp
@@ -7,7 +7,7 @@
 #include "../Deserialization/deserialize.hpp"
 #include "../Memory/MemoryPool.hpp"
 #include "../Polyfills/type_traits.hpp"
-#include "../Variant/VariantRef.hpp"
+#include "../Variant/VariantData.hpp"
 #include "endianess.hpp"
 #include "ieee754.hpp"
 
@@ -17,27 +17,28 @@ template <typename TReader, typename TStringStorage>
 class MsgPackDeserializer {
   typedef typename remove_reference<TStringStorage>::type::StringBuilder
       StringBuilder;
-  typedef typename StringBuilder::StringType StringType;
+  typedef const char *StringType;
 
  public:
-  MsgPackDeserializer(MemoryPool &memoryPool, TReader reader,
+  MsgPackDeserializer(MemoryPool &pool, TReader reader,
                       TStringStorage stringStorage, uint8_t nestingLimit)
-      : _memoryPool(&memoryPool),
+      : _pool(&pool),
         _reader(reader),
         _stringStorage(stringStorage),
         _nestingLimit(nestingLimit) {}
 
-  DeserializationError parse(VariantRef variant) {
+  DeserializationError parse(VariantData &variant) {
     uint8_t code;
     if (!readByte(code)) return DeserializationError::IncompleteInput;
 
     if ((code & 0x80) == 0) {
-      variant.set(code);
+      variant.setUnsignedInteger(code);
       return DeserializationError::Ok;
     }
 
     if ((code & 0xe0) == 0xe0) {
-      variant.set(static_cast<int8_t>(code));
+      // TODO: add setNegativeInteger()
+      variant.setSignedInteger(static_cast<int8_t>(code));
       return DeserializationError::Ok;
     }
 
@@ -45,9 +46,13 @@ class MsgPackDeserializer {
       return readString(variant, code & 0x1f);
     }
 
-    if ((code & 0xf0) == 0x90) return readArray(variant, code & 0x0F);
+    if ((code & 0xf0) == 0x90) {
+      return readArray(variant.toArray(), code & 0x0F);
+    }
 
-    if ((code & 0xf0) == 0x80) return readObject(variant, code & 0x0F);
+    if ((code & 0xf0) == 0x80) {
+      return readObject(variant.toObject(), code & 0x0F);
+    }
 
     switch (code) {
       case 0xc0:
@@ -55,11 +60,11 @@ class MsgPackDeserializer {
         return DeserializationError::Ok;
 
       case 0xc2:
-        variant.set(false);
+        variant.setBoolean(false);
         return DeserializationError::Ok;
 
       case 0xc3:
-        variant.set(true);
+        variant.setBoolean(true);
         return DeserializationError::Ok;
 
       case 0xcc:
@@ -112,16 +117,16 @@ class MsgPackDeserializer {
         return readString<uint32_t>(variant);
 
       case 0xdc:
-        return readArray<uint16_t>(variant);
+        return readArray<uint16_t>(variant.toArray());
 
       case 0xdd:
-        return readArray<uint32_t>(variant);
+        return readArray<uint32_t>(variant.toArray());
 
       case 0xde:
-        return readObject<uint16_t>(variant);
+        return readObject<uint16_t>(variant.toObject());
 
       case 0xdf:
-        return readObject<uint32_t>(variant);
+        return readObject<uint32_t>(variant.toObject());
 
       default:
         return DeserializationError::NotSupported;
@@ -174,48 +179,48 @@ class MsgPackDeserializer {
   }
 
   template <typename T>
-  DeserializationError readInteger(VariantRef variant) {
+  DeserializationError readInteger(VariantData &variant) {
     T value;
     if (!readInteger(value)) return DeserializationError::IncompleteInput;
-    variant.set(value);
+    variant.setInteger(value);
     return DeserializationError::Ok;
   }
 
   template <typename T>
   typename enable_if<sizeof(T) == 4, DeserializationError>::type readFloat(
-      VariantRef variant) {
+      VariantData &variant) {
     T value;
     if (!readBytes(value)) return DeserializationError::IncompleteInput;
     fixEndianess(value);
-    variant.set(value);
+    variant.setFloat(value);
     return DeserializationError::Ok;
   }
 
   template <typename T>
   typename enable_if<sizeof(T) == 8, DeserializationError>::type readDouble(
-      VariantRef variant) {
+      VariantData &variant) {
     T value;
     if (!readBytes(value)) return DeserializationError::IncompleteInput;
     fixEndianess(value);
-    variant.set(value);
+    variant.setFloat(value);
     return DeserializationError::Ok;
   }
 
   template <typename T>
   typename enable_if<sizeof(T) == 4, DeserializationError>::type readDouble(
-      VariantRef variant) {
+      VariantData &variant) {
     uint8_t i[8];  // input is 8 bytes
     T value;       // output is 4 bytes
     uint8_t *o = reinterpret_cast<uint8_t *>(&value);
     if (!readBytes(i, 8)) return DeserializationError::IncompleteInput;
     doubleToFloat(i, o);
     fixEndianess(value);
-    variant.set(value);
+    variant.setFloat(value);
     return DeserializationError::Ok;
   }
 
   template <typename T>
-  DeserializationError readString(VariantRef variant) {
+  DeserializationError readString(VariantData &variant) {
     T size;
     if (!readInteger(size)) return DeserializationError::IncompleteInput;
     return readString(variant, size);
@@ -228,46 +233,40 @@ class MsgPackDeserializer {
     return readString(str, size);
   }
 
-  DeserializationError readString(VariantRef variant, size_t n) {
+  DeserializationError readString(VariantData &variant, size_t n) {
     StringType s;
     DeserializationError err = readString(s, n);
-    if (!err) variant.set(s);
+    if (!err) variant.setOwnedString(s);
     return err;
   }
 
-  DeserializationError readString(StringType &s, size_t n) {
+  DeserializationError readString(StringType &result, size_t n) {
     StringBuilder builder = _stringStorage.startString();
     for (; n; --n) {
       uint8_t c;
       if (!readBytes(c)) return DeserializationError::IncompleteInput;
       builder.append(static_cast<char>(c));
     }
-    s = builder.complete();
-    if (s.isNull()) return DeserializationError::NoMemory;
+    result = builder.complete();
+    if (!result) return DeserializationError::NoMemory;
     return DeserializationError::Ok;
   }
 
   template <typename TSize>
-  DeserializationError readArray(VariantRef variant) {
+  DeserializationError readArray(CollectionData &array) {
     TSize size;
     if (!readInteger(size)) return DeserializationError::IncompleteInput;
-    return readArray(variant, size);
+    return readArray(array, size);
   }
 
-  DeserializationError readArray(VariantRef variant, size_t n) {
-    ArrayRef array = variant.to<ArrayRef>();
-    if (array.isNull()) return DeserializationError::NoMemory;
-    return readArray(array, n);
-  }
-
-  DeserializationError readArray(ArrayRef array, size_t n) {
+  DeserializationError readArray(CollectionData &array, size_t n) {
     if (_nestingLimit == 0) return DeserializationError::TooDeep;
     --_nestingLimit;
     for (; n; --n) {
-      VariantRef value = array.add();
-      if (value.isInvalid()) return DeserializationError::NoMemory;
+      VariantData *value = array.add(_pool);
+      if (!value) return DeserializationError::NoMemory;
 
-      DeserializationError err = parse(value);
+      DeserializationError err = parse(*value);
       if (err) return err;
     }
     ++_nestingLimit;
@@ -275,31 +274,25 @@ class MsgPackDeserializer {
   }
 
   template <typename TSize>
-  DeserializationError readObject(VariantRef variant) {
+  DeserializationError readObject(CollectionData &object) {
     TSize size;
     if (!readInteger(size)) return DeserializationError::IncompleteInput;
-    return readObject(variant, size);
+    return readObject(object, size);
   }
 
-  DeserializationError readObject(VariantRef variant, size_t n) {
-    ObjectRef object = variant.to<ObjectRef>();
-    if (object.isNull()) return DeserializationError::NoMemory;
-
-    return readObject(object, n);
-  }
-
-  DeserializationError readObject(ObjectRef object, size_t n) {
+  DeserializationError readObject(CollectionData &object, size_t n) {
     if (_nestingLimit == 0) return DeserializationError::TooDeep;
     --_nestingLimit;
     for (; n; --n) {
+      VariantSlot *slot = object.addSlot(_pool);
+      if (!slot) return DeserializationError::NoMemory;
+
       StringType key;
       DeserializationError err = parseKey(key);
       if (err) return err;
+      slot->setOwnedKey(key);
 
-      VariantRef value = object.set(key);
-      if (value.isInvalid()) return DeserializationError::NoMemory;
-
-      err = parse(value);
+      err = parse(*slot->data());
       if (err) return err;
     }
     ++_nestingLimit;
@@ -327,7 +320,7 @@ class MsgPackDeserializer {
     }
   }
 
-  MemoryPool *_memoryPool;
+  MemoryPool *_pool;
   TReader _reader;
   TStringStorage _stringStorage;
   uint8_t _nestingLimit;
diff --git a/src/ArduinoJson/MsgPack/MsgPackSerializer.hpp b/src/ArduinoJson/MsgPack/MsgPackSerializer.hpp
index d9fca84d..bb48dfa3 100644
--- a/src/ArduinoJson/MsgPack/MsgPackSerializer.hpp
+++ b/src/ArduinoJson/MsgPack/MsgPackSerializer.hpp
@@ -7,7 +7,7 @@
 #include "../Polyfills/type_traits.hpp"
 #include "../Serialization/measure.hpp"
 #include "../Serialization/serialize.hpp"
-#include "../Variant/VariantRef.hpp"
+#include "../Variant/VariantData.hpp"
 #include "endianess.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
@@ -35,7 +35,7 @@ class MsgPackSerializer {
     }
   }
 
-  void visitArray(ArrayConstRef array) {
+  void visitArray(const CollectionData& array) {
     size_t n = array.size();
     if (n < 0x10) {
       writeByte(uint8_t(0x90 + array.size()));
@@ -46,12 +46,12 @@ class MsgPackSerializer {
       writeByte(0xDD);
       writeInteger(uint32_t(n));
     }
-    for (ArrayConstRef::iterator it = array.begin(); it != array.end(); ++it) {
-      it->accept(*this);
+    for (VariantSlot* slot = array.head(); slot; slot = slot->next()) {
+      slot->data()->accept(*this);
     }
   }
 
-  void visitObject(ObjectConstRef object) {
+  void visitObject(const CollectionData& object) {
     size_t n = object.size();
     if (n < 0x10) {
       writeByte(uint8_t(0x80 + n));
@@ -62,10 +62,9 @@ class MsgPackSerializer {
       writeByte(0xDF);
       writeInteger(uint32_t(n));
     }
-    for (ObjectConstRef::iterator it = object.begin(); it != object.end();
-         ++it) {
-      visitString(it->key());
-      it->value().accept(*this);
+    for (VariantSlot* slot = object.head(); slot; slot = slot->next()) {
+      visitString(slot->key());
+      slot->data()->accept(*this);
     }
   }
 
diff --git a/src/ArduinoJson/Object/Key.hpp b/src/ArduinoJson/Object/Key.hpp
index 13d52a2e..d83c64bb 100644
--- a/src/ArduinoJson/Object/Key.hpp
+++ b/src/ArduinoJson/Object/Key.hpp
@@ -15,7 +15,7 @@ class Key {
   }
 
   const char* c_str() const {
-    return _slot ? slotGetKey(_slot) : 0;
+    return _slot ? _slot->key() : 0;
   }
 
   bool isNull() const {
diff --git a/src/ArduinoJson/Object/ObjectFunctions.hpp b/src/ArduinoJson/Object/ObjectFunctions.hpp
index a06be757..abdebe24 100644
--- a/src/ArduinoJson/Object/ObjectFunctions.hpp
+++ b/src/ArduinoJson/Object/ObjectFunctions.hpp
@@ -4,116 +4,52 @@
 
 #pragma once
 
-#include "../Memory/MemoryPool.hpp"
-#include "../Variant/SlotFunctions.hpp"
-#include "../Variant/VariantData.hpp"
+#include "../Collection/CollectionData.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
 
+template <typename Visitor>
+void objectAccept(const CollectionData *obj, Visitor &visitor) {
+  if (obj)
+    visitor.visitObject(*obj);
+  else
+    visitor.visitNull();
+}
+
 template <typename TKey>
-inline VariantSlot* objectFindSlot(const ObjectData* obj, TKey key) {
+inline bool objectContainsKey(const CollectionData *obj, TKey key) {
+  return obj && obj->containsKey(key);
+}
+
+inline bool objectEquals(const CollectionData *lhs, const CollectionData *rhs) {
+  if (lhs == rhs) return true;
+  if (!lhs || !rhs) return false;
+  return lhs->equalsObject(*rhs);
+}
+
+template <typename TKey>
+inline VariantData *objectGet(const CollectionData *obj, TKey key) {
   if (!obj) return 0;
-  VariantSlot* slot = obj->head;
-  while (slot) {
-    if (key.equals(slotGetKey(slot))) break;
-    slot = slot->getNext();
-  }
-  return slot;
+  return obj->get(key);
 }
 
 template <typename TKey>
-inline bool objectContainsKey(const ObjectData* obj, const TKey& key) {
-  return objectFindSlot(obj, key) != 0;
+void objectRemove(CollectionData *obj, TKey key) {
+  if (!obj) return;
+  obj->remove(key);
 }
 
 template <typename TKey>
-inline VariantData* objectAdd(ObjectData* obj, TKey key, MemoryPool* pool) {
-  VariantSlot* slot = pool->allocVariant();
-  if (!slot) return 0;
-
-  slot->init();
-
-  if (obj->tail) {
-    slot->attachTo(obj->tail);
-    obj->tail = slot;
-  } else {
-    obj->head = slot;
-    obj->tail = slot;
-  }
-
-  if (!slotSetKey(slot, key, pool)) return 0;
-  return slot->getData();
-}
-
-template <typename TKey>
-inline VariantData* objectSet(ObjectData* obj, TKey key, MemoryPool* pool) {
+inline VariantData *objectSet(CollectionData *obj, TKey key, MemoryPool *pool) {
   if (!obj) return 0;
 
   // ignore null key
   if (key.isNull()) return 0;
 
   // search a matching key
-  VariantSlot* slot = objectFindSlot(obj, key);
-  if (slot) return slot->getData();
+  VariantData *var = obj->get(key);
+  if (var) return var;
 
-  return objectAdd(obj, key, pool);
-}
-
-template <typename TKey>
-inline VariantData* objectGet(const ObjectData* obj, TKey key) {
-  VariantSlot* slot = objectFindSlot(obj, key);
-  return slot ? slot->getData() : 0;
-}
-
-inline void objectClear(ObjectData* obj) {
-  if (!obj) return;
-  obj->head = 0;
-  obj->tail = 0;
-}
-
-inline void objectRemove(ObjectData* obj, VariantSlot* slot) {
-  if (!obj) return;
-  if (!slot) return;
-  VariantSlot* prev = slot->getPrev(obj->head);
-  VariantSlot* next = slot->getNext();
-  if (prev)
-    prev->setNext(next);
-  else
-    obj->head = next;
-  if (!next) obj->tail = prev;
-}
-
-inline size_t objectSize(const ObjectData* obj) {
-  if (!obj) return 0;
-  return slotSize(obj->head);
-}
-
-// bool variantCopy(VariantData*, const VariantData*, MemoryPool*);
-
-inline bool objectCopy(ObjectData* dst, const ObjectData* src,
-                       MemoryPool* pool) {
-  if (!dst || !src) return false;
-  objectClear(dst);
-  for (VariantSlot* s = src->head; s; s = s->getNext()) {
-    VariantData* var;
-    if (s->ownsKey())
-      var = objectAdd(dst, ZeroTerminatedRamString(s->key()), pool);
-    else
-      var = objectAdd(dst, ZeroTerminatedRamStringConst(s->key()), pool);
-    if (!variantCopy(var, s->getData(), pool)) return false;
-  }
-  return true;
-}
-
-inline bool objectEquals(const ObjectData* o1, const ObjectData* o2) {
-  if (o1 == o2) return true;
-  if (!o1 || !o2) return false;
-
-  for (VariantSlot* s = o1->head; s; s = s->getNext()) {
-    VariantData* v1 = s->getData();
-    VariantData* v2 = objectGet(o2, makeString(slotGetKey(s)));
-    if (!variantEquals(v1, v2)) return false;
-  }
-  return true;
+  return obj->add(key, pool);
 }
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Object/ObjectIterator.hpp b/src/ArduinoJson/Object/ObjectIterator.hpp
index 4d776e64..e8f72c3d 100644
--- a/src/ArduinoJson/Object/ObjectIterator.hpp
+++ b/src/ArduinoJson/Object/ObjectIterator.hpp
@@ -11,8 +11,7 @@ namespace ARDUINOJSON_NAMESPACE {
 
 class PairPtr {
  public:
-  PairPtr(MemoryPool *memoryPool, VariantSlot *slot)
-      : _pair(memoryPool, slot) {}
+  PairPtr(MemoryPool *pool, VariantSlot *slot) : _pair(pool, slot) {}
 
   const Pair *operator->() const {
     return &_pair;
@@ -30,14 +29,14 @@ class ObjectIterator {
  public:
   ObjectIterator() : _slot(0) {}
 
-  explicit ObjectIterator(MemoryPool *memoryPool, VariantSlot *slot)
-      : _memoryPool(memoryPool), _slot(slot) {}
+  explicit ObjectIterator(MemoryPool *pool, VariantSlot *slot)
+      : _pool(pool), _slot(slot) {}
 
   Pair operator*() const {
-    return Pair(_memoryPool, _slot);
+    return Pair(_pool, _slot);
   }
   PairPtr operator->() {
-    return PairPtr(_memoryPool, _slot);
+    return PairPtr(_pool, _slot);
   }
 
   bool operator==(const ObjectIterator &other) const {
@@ -49,12 +48,12 @@ class ObjectIterator {
   }
 
   ObjectIterator &operator++() {
-    _slot = _slot->getNext();
+    _slot = _slot->next();
     return *this;
   }
 
   ObjectIterator &operator+=(size_t distance) {
-    _slot = _slot->getNext(distance);
+    _slot = _slot->next(distance);
     return *this;
   }
 
@@ -63,7 +62,7 @@ class ObjectIterator {
   }
 
  private:
-  MemoryPool *_memoryPool;
+  MemoryPool *_pool;
   VariantSlot *_slot;
 };
 
@@ -105,12 +104,12 @@ class ObjectConstIterator {
   }
 
   ObjectConstIterator &operator++() {
-    _slot = _slot->getNext();
+    _slot = _slot->next();
     return *this;
   }
 
   ObjectConstIterator &operator+=(size_t distance) {
-    _slot = _slot->getNext(distance);
+    _slot = _slot->next(distance);
     return *this;
   }
 
diff --git a/src/ArduinoJson/Object/ObjectRef.hpp b/src/ArduinoJson/Object/ObjectRef.hpp
index 019d15c7..4d40788f 100644
--- a/src/ArduinoJson/Object/ObjectRef.hpp
+++ b/src/ArduinoJson/Object/ObjectRef.hpp
@@ -17,6 +17,11 @@ namespace ARDUINOJSON_NAMESPACE {
 template <typename TData>
 class ObjectRefBase {
  public:
+  template <typename Visitor>
+  FORCE_INLINE void accept(Visitor& visitor) const {
+    objectAccept(_data, visitor);
+  }
+
   // Tells weither the specified key is present and associated with a value.
   //
   // bool containsKey(TKey);
@@ -38,7 +43,7 @@ class ObjectRefBase {
   }
 
   FORCE_INLINE size_t size() const {
-    return objectSize(_data);
+    return _data ? _data->size() : 0;
   }
 
  protected:
@@ -46,28 +51,20 @@ class ObjectRefBase {
   TData* _data;
 };
 
-class ObjectConstRef : public ObjectRefBase<const ObjectData>,
+class ObjectConstRef : public ObjectRefBase<const CollectionData>,
                        public Visitable {
   friend class ObjectRef;
-  typedef ObjectRefBase<const ObjectData> base_type;
+  typedef ObjectRefBase<const CollectionData> base_type;
 
  public:
   typedef ObjectConstIterator iterator;
 
   ObjectConstRef() : base_type(0) {}
-  ObjectConstRef(const ObjectData* data) : base_type(data) {}
-
-  template <typename Visitor>
-  FORCE_INLINE void accept(Visitor& visitor) const {
-    if (_data)
-      visitor.visitObject(*this);
-    else
-      visitor.visitNull();
-  }
+  ObjectConstRef(const CollectionData* data) : base_type(data) {}
 
   FORCE_INLINE iterator begin() const {
     if (!_data) return iterator();
-    return iterator(_data->head);
+    return iterator(_data->head());
   }
 
   FORCE_INLINE iterator end() const {
@@ -122,18 +119,18 @@ class ObjectConstRef : public ObjectRefBase<const ObjectData>,
   }
 };
 
-class ObjectRef : public ObjectRefBase<ObjectData>, public Visitable {
-  typedef ObjectRefBase<ObjectData> base_type;
+class ObjectRef : public ObjectRefBase<CollectionData>, public Visitable {
+  typedef ObjectRefBase<CollectionData> base_type;
 
  public:
   typedef ObjectIterator iterator;
 
-  FORCE_INLINE ObjectRef() : base_type(0), _memoryPool(0) {}
-  FORCE_INLINE ObjectRef(MemoryPool* buf, ObjectData* data)
-      : base_type(data), _memoryPool(buf) {}
+  FORCE_INLINE ObjectRef() : base_type(0), _pool(0) {}
+  FORCE_INLINE ObjectRef(MemoryPool* buf, CollectionData* data)
+      : base_type(data), _pool(buf) {}
 
   operator VariantRef() const {
-    return VariantRef(_memoryPool, getVariantData(_data));
+    return VariantRef(_pool, reinterpret_cast<VariantData*>(_data));
   }
 
   operator ObjectConstRef() const {
@@ -142,7 +139,7 @@ class ObjectRef : public ObjectRefBase<ObjectData>, public Visitable {
 
   FORCE_INLINE iterator begin() const {
     if (!_data) return iterator();
-    return iterator(_memoryPool, _data->head);
+    return iterator(_pool, _data->head());
   }
 
   FORCE_INLINE iterator end() const {
@@ -150,11 +147,13 @@ class ObjectRef : public ObjectRefBase<ObjectData>, public Visitable {
   }
 
   void clear() const {
-    objectClear(_data);
+    if (!_data) return;
+    _data->clear();
   }
 
   FORCE_INLINE bool copyFrom(ObjectConstRef src) {
-    return objectCopy(_data, src._data, _memoryPool);
+    if (!_data || !src._data) return false;
+    return _data->copyFrom(*src._data, _pool);
   }
 
   // Creates and adds a ArrayRef.
@@ -225,7 +224,8 @@ class ObjectRef : public ObjectRefBase<ObjectData>, public Visitable {
   }
 
   FORCE_INLINE void remove(iterator it) const {
-    objectRemove(_data, it.internal());
+    if (!_data) return;
+    _data->remove(it.internal());
   }
 
   // Removes the specified key and the associated value.
@@ -234,14 +234,14 @@ class ObjectRef : public ObjectRefBase<ObjectData>, public Visitable {
   // TKey = const std::string&, const String&
   template <typename TKey>
   FORCE_INLINE void remove(const TKey& key) const {
-    remove_impl(makeString(key));
+    objectRemove(_data, makeString(key));
   }
   //
   // void remove(TKey);
   // TKey = char*, const char*, char[], const char[], const FlashStringHelper*
   template <typename TKey>
   FORCE_INLINE void remove(TKey* key) const {
-    remove_impl(makeString(key));
+    objectRemove(_data, makeString(key));
   }
 
   template <typename TKey>
@@ -254,35 +254,17 @@ class ObjectRef : public ObjectRefBase<ObjectData>, public Visitable {
     return set_impl(makeString(key));
   }
 
-  FORCE_INLINE VariantRef set(StringInMemoryPool key) const {
-    return set_impl(key);
-  }
-
-  FORCE_INLINE VariantRef set(ZeroTerminatedRamStringConst key) const {
-    return set_impl(key);
-  }
-
-  template <typename Visitor>
-  FORCE_INLINE void accept(Visitor& visitor) const {
-    ObjectConstRef(_data).accept(visitor);
-  }
-
  private:
-  template <typename TStringRef>
-  FORCE_INLINE VariantRef get_impl(TStringRef key) const {
-    return VariantRef(_memoryPool, objectGet(_data, key));
+  template <typename TKey>
+  FORCE_INLINE VariantRef get_impl(TKey key) const {
+    return VariantRef(_pool, objectGet(_data, key));
   }
 
   template <typename TKey>
   FORCE_INLINE VariantRef set_impl(TKey key) const {
-    return VariantRef(_memoryPool, objectSet(_data, key, _memoryPool));
+    return VariantRef(_pool, objectSet(_data, key, _pool));
   }
 
-  template <typename TStringRef>
-  FORCE_INLINE void remove_impl(TStringRef key) const {
-    objectRemove(_data, objectFindSlot(_data, key));
-  }
-
-  MemoryPool* _memoryPool;
+  MemoryPool* _pool;
 };
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Object/Pair.hpp b/src/ArduinoJson/Object/Pair.hpp
index 4c48ee0f..d13ea6b5 100644
--- a/src/ArduinoJson/Object/Pair.hpp
+++ b/src/ArduinoJson/Object/Pair.hpp
@@ -8,12 +8,12 @@
 #include "Key.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
-// A key value pair for ObjectData.
+// A key value pair for CollectionData.
 class Pair {
  public:
-  Pair(MemoryPool* memoryPool, VariantSlot* slot) : _key(slot) {
+  Pair(MemoryPool* pool, VariantSlot* slot) : _key(slot) {
     if (slot) {
-      _value = VariantRef(memoryPool, slot->getData());
+      _value = VariantRef(pool, slot->data());
     }
   }
 
@@ -34,7 +34,7 @@ class PairConst {
  public:
   PairConst(const VariantSlot* slot) : _key(slot) {
     if (slot) {
-      _value = VariantConstRef(slot->getData());
+      _value = VariantConstRef(slot->data());
     }
   }
 
diff --git a/src/ArduinoJson/Polyfills/type_traits/is_array.hpp b/src/ArduinoJson/Polyfills/type_traits/is_array.hpp
index 34321e56..e5e23f9f 100644
--- a/src/ArduinoJson/Polyfills/type_traits/is_array.hpp
+++ b/src/ArduinoJson/Polyfills/type_traits/is_array.hpp
@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include <stddef.h>  // size_t
+
 namespace ARDUINOJSON_NAMESPACE {
 
 template <typename T>
diff --git a/src/ArduinoJson/StringStorage/StringCopier.hpp b/src/ArduinoJson/StringStorage/StringCopier.hpp
index e6c5b7cb..6082dde2 100644
--- a/src/ArduinoJson/StringStorage/StringCopier.hpp
+++ b/src/ArduinoJson/StringStorage/StringCopier.hpp
@@ -13,13 +13,13 @@ class StringCopier {
  public:
   typedef ARDUINOJSON_NAMESPACE::StringBuilder StringBuilder;
 
-  StringCopier(MemoryPool* memoryPool) : _memoryPool(memoryPool) {}
+  StringCopier(MemoryPool* pool) : _pool(pool) {}
 
   StringBuilder startString() {
-    return StringBuilder(_memoryPool);
+    return StringBuilder(_pool);
   }
 
  private:
-  MemoryPool* _memoryPool;
+  MemoryPool* _pool;
 };
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/StringStorage/StringMover.hpp b/src/ArduinoJson/StringStorage/StringMover.hpp
index 5450e6de..5f934562 100644
--- a/src/ArduinoJson/StringStorage/StringMover.hpp
+++ b/src/ArduinoJson/StringStorage/StringMover.hpp
@@ -10,17 +10,15 @@ class StringMover {
  public:
   class StringBuilder {
    public:
-    typedef ZeroTerminatedRamStringConst StringType;
-
     StringBuilder(char** ptr) : _writePtr(ptr), _startPtr(*ptr) {}
 
     void append(char c) {
       *(*_writePtr)++ = char(c);
     }
 
-    StringType complete() const {
+    char* complete() const {
       *(*_writePtr)++ = 0;
-      return reinterpret_cast<const char*>(_startPtr);
+      return _startPtr;
     }
 
    private:
diff --git a/src/ArduinoJson/Strings/ArduinoString.hpp b/src/ArduinoJson/Strings/ArduinoString.hpp
index 30962c2d..fb3f1de8 100644
--- a/src/ArduinoJson/Strings/ArduinoString.hpp
+++ b/src/ArduinoJson/Strings/ArduinoString.hpp
@@ -12,10 +12,10 @@ class ArduinoString {
  public:
   ArduinoString(const ::String& str) : _str(&str) {}
 
-  char* save(MemoryPool* memoryPool) const {
+  char* save(MemoryPool* pool) const {
     if (isNull()) return NULL;
     size_t n = _str->length() + 1;
-    char* dup = memoryPool->allocFrozenString(n);
+    char* dup = pool->allocFrozenString(n);
     if (dup) memcpy(dup, _str->c_str(), n);
     return dup;
   }
diff --git a/src/ArduinoJson/Strings/FixedSizeFlashString.hpp b/src/ArduinoJson/Strings/FixedSizeFlashString.hpp
index f9b75fc6..afa76fc5 100644
--- a/src/ArduinoJson/Strings/FixedSizeFlashString.hpp
+++ b/src/ArduinoJson/Strings/FixedSizeFlashString.hpp
@@ -21,9 +21,9 @@ class FixedSizeFlashString {
     return !_str;
   }
 
-  char* save(MemoryPool* memoryPool) const {
+  char* save(MemoryPool* pool) const {
     if (!_str) return NULL;
-    char* dup = memoryPool->allocFrozenString(_size);
+    char* dup = pool->allocFrozenString(_size);
     if (!dup) memcpy_P(dup, (const char*)_str, _size);
     return dup;
   }
diff --git a/src/ArduinoJson/Strings/FixedSizeRamString.hpp b/src/ArduinoJson/Strings/FixedSizeRamString.hpp
index 90beaecc..00da6503 100644
--- a/src/ArduinoJson/Strings/FixedSizeRamString.hpp
+++ b/src/ArduinoJson/Strings/FixedSizeRamString.hpp
@@ -22,10 +22,9 @@ class FixedSizeRamString {
     return !_str;
   }
 
-  template <typename TMemoryPool>
-  char* save(TMemoryPool* memoryPool) const {
+  char* save(MemoryPool* pool) const {
     if (!_str) return NULL;
-    char* dup = memoryPool->allocFrozenString(_size);
+    char* dup = pool->allocFrozenString(_size);
     if (dup) memcpy(dup, _str, _size);
     return dup;
   }
diff --git a/src/ArduinoJson/Strings/StlString.hpp b/src/ArduinoJson/Strings/StlString.hpp
index fd0c63ec..12457ec3 100644
--- a/src/ArduinoJson/Strings/StlString.hpp
+++ b/src/ArduinoJson/Strings/StlString.hpp
@@ -12,9 +12,9 @@ class StlString {
  public:
   StlString(const std::string& str) : _str(&str) {}
 
-  char* save(MemoryPool* memoryPool) const {
+  char* save(MemoryPool* pool) const {
     size_t n = _str->length() + 1;
-    char* dup = memoryPool->allocFrozenString(n);
+    char* dup = pool->allocFrozenString(n);
     if (dup) memcpy(dup, _str->c_str(), n);
     return dup;
   }
diff --git a/src/ArduinoJson/Strings/StringInMemoryPool.hpp b/src/ArduinoJson/Strings/StringInMemoryPool.hpp
deleted file mode 100644
index ee79b988..00000000
--- a/src/ArduinoJson/Strings/StringInMemoryPool.hpp
+++ /dev/null
@@ -1,39 +0,0 @@
-// ArduinoJson - arduinojson.org
-// Copyright Benoit Blanchon 2014-2018
-// MIT License
-
-#pragma once
-
-#include <string.h>
-#include "../Memory/MemoryPool.hpp"
-
-namespace ARDUINOJSON_NAMESPACE {
-
-class StringInMemoryPool {
- public:
-  StringInMemoryPool(char* s = 0) : _value(s) {}
-
-  bool equals(const char* expected) const {
-    if (!_value) return expected == 0;
-    const char* actual = _value;
-    if (actual == expected) return true;
-    return strcmp(actual, expected) == 0;
-  }
-
-  char* save(void*) {
-    return _value;
-  }
-
-  bool isNull() const {
-    return !_value;
-  }
-
-  const char* c_str() const {
-    return _value;
-  }
-
- protected:
-  char* _value;
-};
-
-}  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Strings/StringTypes.hpp b/src/ArduinoJson/Strings/StringTypes.hpp
index 0f055563..82481180 100644
--- a/src/ArduinoJson/Strings/StringTypes.hpp
+++ b/src/ArduinoJson/Strings/StringTypes.hpp
@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include "../Memory/MemoryPool.hpp"
 #include "../Polyfills/type_traits.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
@@ -18,7 +19,6 @@ struct IsString<T&> : IsString<T> {};
 }  // namespace ARDUINOJSON_NAMESPACE
 
 #include "FixedSizeRamString.hpp"
-#include "StringInMemoryPool.hpp"
 #include "ZeroTerminatedRamString.hpp"
 #include "ZeroTerminatedRamStringConst.hpp"
 
diff --git a/src/ArduinoJson/Strings/ZeroTerminatedFlashString.hpp b/src/ArduinoJson/Strings/ZeroTerminatedFlashString.hpp
index 93d0d19e..cf3f22ab 100644
--- a/src/ArduinoJson/Strings/ZeroTerminatedFlashString.hpp
+++ b/src/ArduinoJson/Strings/ZeroTerminatedFlashString.hpp
@@ -20,10 +20,10 @@ class ZeroTerminatedFlashString {
     return !_str;
   }
 
-  char* save(MemoryPool* memoryPool) const {
+  char* save(MemoryPool* pool) const {
     if (!_str) return NULL;
     size_t n = size() + 1;  // copy the terminator
-    char* dup = memoryPool->allocFrozenString(n);
+    char* dup = pool->allocFrozenString(n);
     if (dup) memcpy_P(dup, reinterpret_cast<const char*>(_str), n);
     return dup;
   }
diff --git a/src/ArduinoJson/Strings/ZeroTerminatedRamString.hpp b/src/ArduinoJson/Strings/ZeroTerminatedRamString.hpp
index fac8cf04..db4384fd 100644
--- a/src/ArduinoJson/Strings/ZeroTerminatedRamString.hpp
+++ b/src/ArduinoJson/Strings/ZeroTerminatedRamString.hpp
@@ -13,11 +13,10 @@ class ZeroTerminatedRamString : public ZeroTerminatedRamStringConst {
   ZeroTerminatedRamString(const char* str)
       : ZeroTerminatedRamStringConst(str) {}
 
-  template <typename TMemoryPool>
-  char* save(TMemoryPool* memoryPool) const {
+  char* save(MemoryPool* pool) const {
     if (!_str) return NULL;
     size_t n = size() + 1;
-    char* dup = memoryPool->allocFrozenString(n);
+    char* dup = pool->allocFrozenString(n);
     if (dup) memcpy(dup, _str, n);
     return dup;
   }
diff --git a/src/ArduinoJson/Variant/SlotFunctions.hpp b/src/ArduinoJson/Variant/SlotFunctions.hpp
index e083943d..5e86b720 100644
--- a/src/ArduinoJson/Variant/SlotFunctions.hpp
+++ b/src/ArduinoJson/Variant/SlotFunctions.hpp
@@ -13,32 +13,25 @@ namespace ARDUINOJSON_NAMESPACE {
 
 template <typename TKey>
 inline bool slotSetKey(VariantSlot* var, TKey key, MemoryPool* pool) {
+  if (!var) return false;
   char* dup = key.save(pool);
   if (!dup) return false;
-  var->setKey(dup, true);
+  var->setOwnedKey(dup);
   return true;
 }
 
 inline bool slotSetKey(VariantSlot* var, ZeroTerminatedRamStringConst key,
                        MemoryPool*) {
-  var->setKey(key.c_str(), false);
+  if (!var) return false;
+  var->setLinkedKey(key.c_str());
   return true;
 }
 
-inline bool slotSetKey(VariantSlot* var, StringInMemoryPool key, MemoryPool*) {
-  var->setKey(key.c_str(), true);
-  return true;
-}
-
-inline const char* slotGetKey(const VariantSlot* var) {
-  return var->key();
-}
-
 inline size_t slotSize(const VariantSlot* var) {
   size_t n = 0;
   while (var) {
     n++;
-    var = var->getNext();
+    var = var->next();
   }
   return n;
 }
diff --git a/src/ArduinoJson/Variant/VariantAs.hpp b/src/ArduinoJson/Variant/VariantAs.hpp
index d5d3dfb3..2212e714 100644
--- a/src/ArduinoJson/Variant/VariantAs.hpp
+++ b/src/ArduinoJson/Variant/VariantAs.hpp
@@ -5,7 +5,6 @@
 #pragma once
 
 #include "../Serialization/DynamicStringWriter.hpp"
-#include "VariantFunctions.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
 
@@ -55,19 +54,19 @@ struct VariantConstAs<ArrayRef> {
 template <typename T>
 inline typename enable_if<is_integral<T>::value, T>::type variantAs(
     const VariantData* _data) {
-  return variantAsIntegral<T>(_data);
+  return _data != 0 ? _data->asIntegral<T>() : T(0);
 }
 
 template <typename T>
 inline typename enable_if<is_same<T, bool>::value, T>::type variantAs(
     const VariantData* _data) {
-  return variantAsBoolean(_data);
+  return _data != 0 ? _data->asBoolean() : false;
 }
 
 template <typename T>
 inline typename enable_if<is_floating_point<T>::value, T>::type variantAs(
     const VariantData* _data) {
-  return variantAsFloat<T>(_data);
+  return _data != 0 ? _data->asFloat<T>() : T(0);
 }
 
 template <typename T>
@@ -75,7 +74,7 @@ inline typename enable_if<is_same<T, const char*>::value ||
                               is_same<T, char*>::value,
                           const char*>::type
 variantAs(const VariantData* _data) {
-  return variantAsString(_data);
+  return _data != 0 ? _data->asString() : 0;
 }
 
 template <typename T>
diff --git a/src/ArduinoJson/Variant/VariantAsImpl.hpp b/src/ArduinoJson/Variant/VariantAsImpl.hpp
index 72230f2c..8836a9fd 100644
--- a/src/ArduinoJson/Variant/VariantAsImpl.hpp
+++ b/src/ArduinoJson/Variant/VariantAsImpl.hpp
@@ -5,7 +5,6 @@
 #pragma once
 
 #include "../Serialization/DynamicStringWriter.hpp"
-#include "VariantFunctions.hpp"
 #include "VariantRef.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
@@ -19,7 +18,7 @@ variantAs(const VariantData* _data) {
 template <typename T>
 inline typename enable_if<IsWriteableString<T>::value, T>::type variantAs(
     const VariantData* _data) {
-  const char* cstr = variantAsString(_data);
+  const char* cstr = _data != 0 ? _data->asString() : 0;
   if (cstr) return T(cstr);
   T s;
   serializeJson(VariantConstRef(_data), s);
diff --git a/src/ArduinoJson/Variant/VariantContent.hpp b/src/ArduinoJson/Variant/VariantContent.hpp
new file mode 100644
index 00000000..aac4a538
--- /dev/null
+++ b/src/ArduinoJson/Variant/VariantContent.hpp
@@ -0,0 +1,46 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2018
+// MIT License
+
+#pragma once
+
+#include <stddef.h>  // size_t
+
+#include "../Collection/CollectionData.hpp"
+#include "../Numbers/Float.hpp"
+#include "../Numbers/Integer.hpp"
+
+namespace ARDUINOJSON_NAMESPACE {
+
+enum {
+  VALUE_IS_NULL = 0,
+  VALUE_IS_LINKED_RAW,
+  VALUE_IS_OWNED_RAW,
+  VALUE_IS_LINKED_STRING,
+  VALUE_IS_OWNED_STRING,
+  VALUE_IS_BOOLEAN,
+  VALUE_IS_POSITIVE_INTEGER,
+  VALUE_IS_NEGATIVE_INTEGER,
+  VALUE_IS_ARRAY,
+  VALUE_IS_OBJECT,
+  VALUE_IS_FLOAT,
+  VALUE_MASK = 0x7F,
+  KEY_IS_OWNED = 0x80
+};
+
+struct RawData {
+  const char *data;
+  size_t size;
+};
+
+union VariantContent {
+  Float asFloat;
+  UInt asInteger;
+  CollectionData asCollection;
+  const char *asString;
+  struct {
+    const char *data;
+    size_t size;
+  } asRaw;
+};
+}  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Variant/VariantData.hpp b/src/ArduinoJson/Variant/VariantData.hpp
index 88e14b34..969dc937 100644
--- a/src/ArduinoJson/Variant/VariantData.hpp
+++ b/src/ArduinoJson/Variant/VariantData.hpp
@@ -4,78 +4,285 @@
 
 #pragma once
 
-#include <stddef.h>  // ptrdiff_t, size_t
-
-#include "../Numbers/Float.hpp"
-#include "../Numbers/Integer.hpp"
+#include "../Misc/SerializedValue.hpp"
+#include "VariantContent.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
 
-class VariantSlot;
+class VariantData {
+  VariantContent _content;  // must be first to allow cast from array to variant
+  uint8_t _flags;
 
-enum VariantType {
-  JSON_NULL,
-  JSON_LINKED_RAW,
-  JSON_OWNED_RAW,
-  JSON_LINKED_STRING,
-  JSON_OWNED_STRING,
-  JSON_BOOLEAN,
-  JSON_POSITIVE_INTEGER,
-  JSON_NEGATIVE_INTEGER,
-  JSON_ARRAY,
-  JSON_OBJECT,
-  JSON_FLOAT
+ public:
+  // Must be a POD!
+  // - no constructor
+  // - no destructor
+  // - no virtual
+  // - no inheritance
+
+  template <typename Visitor>
+  void accept(Visitor &visitor) const {
+    switch (type()) {
+      case VALUE_IS_FLOAT:
+        return visitor.visitFloat(_content.asFloat);
+
+      case VALUE_IS_ARRAY:
+        return visitor.visitArray(_content.asCollection);
+
+      case VALUE_IS_OBJECT:
+        return visitor.visitObject(_content.asCollection);
+
+      case VALUE_IS_LINKED_STRING:
+      case VALUE_IS_OWNED_STRING:
+        return visitor.visitString(_content.asString);
+
+      case VALUE_IS_OWNED_RAW:
+      case VALUE_IS_LINKED_RAW:
+        return visitor.visitRawJson(_content.asRaw.data, _content.asRaw.size);
+
+      case VALUE_IS_NEGATIVE_INTEGER:
+        return visitor.visitNegativeInteger(_content.asInteger);
+
+      case VALUE_IS_POSITIVE_INTEGER:
+        return visitor.visitPositiveInteger(_content.asInteger);
+
+      case VALUE_IS_BOOLEAN:
+        return visitor.visitBoolean(_content.asInteger != 0);
+
+      default:
+        return visitor.visitNull();
+    }
+  }
+
+  template <typename T>
+  T asIntegral() const;
+
+  template <typename T>
+  T asFloat() const;
+
+  const char *asString() const;
+
+  bool asBoolean() const {
+    return asIntegral<int>() != 0;
+  }
+
+  CollectionData *asArray() {
+    if (type() == VALUE_IS_ARRAY)
+      return &_content.asCollection;
+    else
+      return 0;
+  }
+
+  const CollectionData *asArray() const {
+    return const_cast<VariantData *>(this)->asArray();
+  }
+
+  CollectionData *asObject() {
+    if (type() == VALUE_IS_OBJECT)
+      return &_content.asCollection;
+    else
+      return 0;
+  }
+
+  const CollectionData *asObject() const {
+    return const_cast<VariantData *>(this)->asObject();
+  }
+
+  bool copyFrom(const VariantData &src, MemoryPool *pool) {
+    switch (src.type()) {
+      case VALUE_IS_ARRAY:
+        return toArray().copyFrom(src._content.asCollection, pool);
+      case VALUE_IS_OBJECT:
+        return toObject().copyFrom(src._content.asCollection, pool);
+      case VALUE_IS_OWNED_STRING:
+        return setOwnedString(ZeroTerminatedRamString(src._content.asString),
+                              pool);
+      case VALUE_IS_OWNED_RAW:
+        return setOwnedRaw(
+            serialized(src._content.asRaw.data, src._content.asRaw.size), pool);
+      default:
+        setType(src.type());
+        _content = src._content;
+        return true;
+    }
+  }
+
+  bool equals(const VariantData &other) const {
+    if (type() != other.type()) return false;
+
+    switch (type()) {
+      case VALUE_IS_LINKED_STRING:
+      case VALUE_IS_OWNED_STRING:
+        return !strcmp(_content.asString, other._content.asString);
+
+      case VALUE_IS_LINKED_RAW:
+      case VALUE_IS_OWNED_RAW:
+        return _content.asRaw.size == other._content.asRaw.size &&
+               !memcmp(_content.asRaw.data, other._content.asRaw.data,
+                       _content.asRaw.size);
+
+      case VALUE_IS_BOOLEAN:
+      case VALUE_IS_POSITIVE_INTEGER:
+      case VALUE_IS_NEGATIVE_INTEGER:
+        return _content.asInteger == other._content.asInteger;
+
+      case VALUE_IS_ARRAY:
+        return _content.asCollection.equalsArray(other._content.asCollection);
+
+      case VALUE_IS_OBJECT:
+        return _content.asCollection.equalsObject(other._content.asCollection);
+
+      case VALUE_IS_FLOAT:
+        return _content.asFloat == other._content.asFloat;
+
+      case VALUE_IS_NULL:
+      default:
+        return true;
+    }
+  }
+
+  bool isArray() const {
+    return type() == VALUE_IS_ARRAY;
+  }
+
+  bool isBoolean() const {
+    return type() == VALUE_IS_BOOLEAN;
+  }
+
+  bool isInteger() const {
+    return type() == VALUE_IS_POSITIVE_INTEGER ||
+           type() == VALUE_IS_NEGATIVE_INTEGER;
+  }
+
+  bool isFloat() const {
+    return type() == VALUE_IS_FLOAT || type() == VALUE_IS_POSITIVE_INTEGER ||
+           type() == VALUE_IS_NEGATIVE_INTEGER;
+  }
+
+  bool isString() const {
+    return (type() == VALUE_IS_LINKED_STRING ||
+            type() == VALUE_IS_OWNED_STRING);
+  }
+
+  bool isObject() const {
+    return type() == VALUE_IS_OBJECT;
+  }
+
+  bool isNull() const {
+    return type() == VALUE_IS_NULL;
+  }
+
+  void setBoolean(bool value) {
+    setType(VALUE_IS_BOOLEAN);
+    _content.asInteger = static_cast<UInt>(value);
+  }
+
+  void setFloat(Float value) {
+    setType(VALUE_IS_FLOAT);
+    _content.asFloat = value;
+  }
+
+  void setLinkedRaw(SerializedValue<const char *> value) {
+    setType(VALUE_IS_LINKED_RAW);
+    _content.asRaw.data = value.data();
+    _content.asRaw.size = value.size();
+  }
+
+  template <typename T>
+  bool setOwnedRaw(SerializedValue<T> value, MemoryPool *pool) {
+    char *dup = makeString(value.data(), value.size()).save(pool);
+    if (dup) {
+      setType(VALUE_IS_OWNED_RAW);
+      _content.asRaw.data = dup;
+      _content.asRaw.size = value.size();
+      return true;
+    } else {
+      setType(VALUE_IS_NULL);
+      return false;
+    }
+  }
+
+  template <typename T>
+  typename enable_if<is_unsigned<T>::value>::type setInteger(T value) {
+    setUnsignedInteger(value);
+  }
+
+  template <typename T>
+  typename enable_if<is_signed<T>::value>::type setInteger(T value) {
+    setSignedInteger(value);
+  }
+
+  template <typename T>
+  void setSignedInteger(T value) {
+    if (value >= 0) {
+      setType(VALUE_IS_POSITIVE_INTEGER);
+      _content.asInteger = static_cast<UInt>(value);
+    } else {
+      setType(VALUE_IS_NEGATIVE_INTEGER);
+      _content.asInteger = ~static_cast<UInt>(value) + 1;
+    }
+  }
+
+  void setLinkedString(const char *value) {
+    setType(VALUE_IS_LINKED_STRING);
+    _content.asString = value;
+  }
+
+  void setNull() {
+    setType(VALUE_IS_NULL);
+  }
+
+  void setOwnedString(const char *s) {
+    setType(VALUE_IS_OWNED_STRING);
+    _content.asString = s;
+  }
+
+  template <typename T>
+  bool setOwnedString(T value, MemoryPool *pool) {
+    char *dup = value.save(pool);
+    if (dup) {
+      setType(VALUE_IS_OWNED_STRING);
+      _content.asString = dup;
+      return true;
+    } else {
+      setType(VALUE_IS_NULL);
+      return false;
+    }
+  }
+
+  void setUnsignedInteger(UInt value) {
+    setType(VALUE_IS_POSITIVE_INTEGER);
+    _content.asInteger = static_cast<UInt>(value);
+  }
+
+  CollectionData &toArray() {
+    setType(VALUE_IS_ARRAY);
+    _content.asCollection.clear();
+    return _content.asCollection;
+  }
+
+  CollectionData &toObject() {
+    setType(VALUE_IS_OBJECT);
+    _content.asCollection.clear();
+    return _content.asCollection;
+  }
+
+  size_t size() const {
+    if (type() == VALUE_IS_OBJECT || type() == VALUE_IS_ARRAY)
+      return _content.asCollection.size();
+    else
+      return 0;
+  }
+
+ private:
+  uint8_t type() const {
+    return _flags & VALUE_MASK;
+  }
+
+  void setType(uint8_t t) {
+    _flags &= KEY_IS_OWNED;
+    _flags |= t;
+  }
 };
 
-struct ObjectData {
-  VariantSlot *head;
-  VariantSlot *tail;
-};
-
-struct ArrayData {
-  VariantSlot *head;
-  VariantSlot *tail;
-};
-
-struct RawData {
-  const char *data;
-  size_t size;
-};
-
-// A union that defines the actual content of a VariantData.
-// The enum VariantType determines which member is in use.
-union VariantContent {
-  Float asFloat;
-  UInt asInteger;
-  ArrayData asArray;
-  ObjectData asObject;
-  const char *asString;
-  struct {
-    const char *data;
-    size_t size;
-  } asRaw;
-};
-
-// this struct must be a POD type to prevent error calling offsetof on clang
-struct VariantData {
-  VariantContent content;
-  bool keyIsOwned : 1;
-  VariantType type : 7;
-};
-
-inline VariantData *getVariantData(ArrayData *arr) {
-  const ptrdiff_t offset =
-      offsetof(VariantData, content) - offsetof(VariantContent, asArray);
-  if (!arr) return 0;
-  return reinterpret_cast<VariantData *>(reinterpret_cast<char *>(arr) -
-                                         offset);
-}
-
-inline VariantData *getVariantData(ObjectData *obj) {
-  const ptrdiff_t offset =
-      offsetof(VariantData, content) - offsetof(VariantContent, asObject);
-  if (!obj) return 0;
-  return reinterpret_cast<VariantData *>(reinterpret_cast<char *>(obj) -
-                                         offset);
-}
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Variant/VariantFunctions.hpp b/src/ArduinoJson/Variant/VariantFunctions.hpp
index 7d85c617..3c965b66 100644
--- a/src/ArduinoJson/Variant/VariantFunctions.hpp
+++ b/src/ArduinoJson/Variant/VariantFunctions.hpp
@@ -4,292 +4,142 @@
 
 #pragma once
 
-#include "../Array/ArrayFunctions.hpp"
-#include "../Misc/SerializedValue.hpp"
-#include "../Numbers/parseFloat.hpp"
-#include "../Numbers/parseInteger.hpp"
-#include "../Object/ObjectFunctions.hpp"
 #include "VariantData.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
-template <typename T>
-inline T variantAsIntegral(const VariantData* var) {
-  if (!var) return 0;
-  switch (var->type) {
-    case JSON_POSITIVE_INTEGER:
-    case JSON_BOOLEAN:
-      return T(var->content.asInteger);
-    case JSON_NEGATIVE_INTEGER:
-      return T(~var->content.asInteger + 1);
-    case JSON_LINKED_STRING:
-    case JSON_OWNED_STRING:
-      return parseInteger<T>(var->content.asString);
-    case JSON_FLOAT:
-      return T(var->content.asFloat);
-    default:
-      return 0;
-  }
-}
 
-inline bool variantAsBoolean(const VariantData* var) {
-  return variantAsIntegral<int>(var) != 0;
-}
-
-// T = float/double
-template <typename T>
-inline T variantAsFloat(const VariantData* var) {
-  if (!var) return 0;
-  switch (var->type) {
-    case JSON_POSITIVE_INTEGER:
-    case JSON_BOOLEAN:
-      return static_cast<T>(var->content.asInteger);
-    case JSON_NEGATIVE_INTEGER:
-      return -static_cast<T>(var->content.asInteger);
-    case JSON_LINKED_STRING:
-    case JSON_OWNED_STRING:
-      return parseFloat<T>(var->content.asString);
-    case JSON_FLOAT:
-      return static_cast<T>(var->content.asFloat);
-    default:
-      return 0;
-  }
-}
-
-inline const char* variantAsString(const VariantData* var) {
-  if (!var) return 0;
-  switch (var->type) {
-    case JSON_LINKED_STRING:
-    case JSON_OWNED_STRING:
-      return var->content.asString;
-    default:
-      return 0;
-  }
-}
-
-inline ArrayData* variantAsArray(VariantData* var) {
-  if (var && var->type == JSON_ARRAY)
-    return &var->content.asArray;
+template <typename Visitor>
+inline void variantAccept(const VariantData *var, Visitor &visitor) {
+  if (var != 0)
+    var->accept(visitor);
   else
-    return 0;
+    visitor.visitNull();
 }
 
-inline const ArrayData* variantAsArray(const VariantData* var) {
-  if (var && var->type == JSON_ARRAY)
-    return &var->content.asArray;
-  else
-    return 0;
+inline const CollectionData *variantAsObject(const VariantData *var) {
+  return var != 0 ? var->asObject() : 0;
 }
 
-inline ObjectData* variantAsObject(VariantData* var) {
-  if (var && var->type == JSON_OBJECT)
-    return &var->content.asObject;
-  else
-    return 0;
+inline CollectionData *variantAsObject(VariantData *var) {
+  return var != 0 ? var->asObject() : 0;
 }
 
-inline const ObjectData* variantAsObject(const VariantData* var) {
-  if (var && var->type == JSON_OBJECT)
-    return &var->content.asObject;
-  else
-    return 0;
-}
-
-inline bool variantSetBoolean(VariantData* var, bool value) {
-  if (!var) return false;
-  var->type = JSON_BOOLEAN;
-  var->content.asInteger = static_cast<UInt>(value);
-  return true;
-}
-
-inline bool variantSetFloat(VariantData* var, Float value) {
-  if (!var) return false;
-  var->type = JSON_FLOAT;
-  var->content.asFloat = value;
-  return true;
-}
-
-template <typename T>
-inline bool variantSetSignedInteger(VariantData* var, T value) {
-  if (!var) return false;
-  if (value >= 0) {
-    var->type = JSON_POSITIVE_INTEGER;
-    var->content.asInteger = static_cast<UInt>(value);
-  } else {
-    var->type = JSON_NEGATIVE_INTEGER;
-    var->content.asInteger = ~static_cast<UInt>(value) + 1;
-  }
-  return true;
-}
-
-inline bool variantSetUnsignedInteger(VariantData* var, UInt value) {
-  if (!var) return false;
-  var->type = JSON_POSITIVE_INTEGER;
-  var->content.asInteger = static_cast<UInt>(value);
-  return true;
-}
-
-inline bool variantSetLinkedRaw(VariantData* var,
-                                SerializedValue<const char*> value) {
-  if (!var) return false;
-  var->type = JSON_LINKED_RAW;
-  var->content.asRaw.data = value.data();
-  var->content.asRaw.size = value.size();
-  return true;
-}
-
-template <typename T>
-inline bool variantSetOwnedRaw(VariantData* var, SerializedValue<T> value,
-                               MemoryPool* pool) {
-  if (!var) return false;
-  char* dup = makeString(value.data(), value.size()).save(pool);
-  if (dup) {
-    var->type = JSON_OWNED_RAW;
-    var->content.asRaw.data = dup;
-    var->content.asRaw.size = value.size();
-    return true;
-  } else {
-    var->type = JSON_NULL;
-    return false;
-  }
-}
-
-template <typename T>
-inline bool variantSetString(VariantData* var, T value, MemoryPool* pool) {
-  if (!var) return false;
-  char* dup = value.save(pool);
-  if (dup) {
-    var->type = JSON_OWNED_STRING;
-    var->content.asString = dup;
-    return true;
-  } else {
-    var->type = JSON_NULL;
-    return false;
-  }
-}
-
-inline bool variantSetOwnedString(VariantData* var, char* s) {
-  if (!var) return false;
-  var->type = JSON_OWNED_STRING;
-  var->content.asString = s;
-  return true;
-}
-
-inline bool variantSetString(VariantData* var, const char* value) {
-  if (!var) return false;
-  var->type = JSON_LINKED_STRING;
-  var->content.asString = value;
-  return true;
-}
-
-inline void variantSetNull(VariantData* var) {
-  if (!var) return;
-  var->type = JSON_NULL;
-}
-
-inline ArrayData* variantToArray(VariantData* var) {
-  if (!var) return 0;
-  var->type = JSON_ARRAY;
-  var->content.asArray.head = 0;
-  var->content.asArray.tail = 0;
-  return &var->content.asArray;
-}
-
-inline ObjectData* variantToObject(VariantData* var) {
-  if (!var) return 0;
-  var->type = JSON_OBJECT;
-  var->content.asObject.head = 0;
-  var->content.asObject.tail = 0;
-  return &var->content.asObject;
-}
-
-inline bool variantCopy(VariantData* dst, const VariantData* src,
-                        MemoryPool* pool) {
+inline bool variantCopyFrom(VariantData *dst, const VariantData *src,
+                            MemoryPool *pool) {
   if (!dst) return false;
   if (!src) {
-    dst->type = JSON_NULL;
+    dst->setNull();
     return true;
   }
-  switch (src->type) {
-    case JSON_ARRAY:
-      return arrayCopy(variantToArray(dst), &src->content.asArray, pool);
-    case JSON_OBJECT:
-      return objectCopy(variantToObject(dst), &src->content.asObject, pool);
-    case JSON_OWNED_STRING:
-      return variantSetString(
-          dst, ZeroTerminatedRamString(src->content.asString), pool);
-    case JSON_OWNED_RAW:
-      return variantSetOwnedRaw(
-          dst, serialized(src->content.asRaw.data, src->content.asRaw.size),
-          pool);
-    default:
-      // caution: don't override keyIsOwned
-      dst->type = src->type;
-      dst->content = src->content;
-      return true;
-  }
+  return dst->copyFrom(*src, pool);
 }
 
-inline bool variantIsInteger(const VariantData* var) {
-  return var && (var->type == JSON_POSITIVE_INTEGER ||
-                 var->type == JSON_NEGATIVE_INTEGER);
-}
-
-inline bool variantIsFloat(const VariantData* var) {
-  return var &&
-         (var->type == JSON_FLOAT || var->type == JSON_POSITIVE_INTEGER ||
-          var->type == JSON_NEGATIVE_INTEGER);
-}
-
-inline bool variantIsString(const VariantData* var) {
-  return var &&
-         (var->type == JSON_LINKED_STRING || var->type == JSON_OWNED_STRING);
-}
-
-inline bool variantIsArray(const VariantData* var) {
-  return var && var->type == JSON_ARRAY;
-}
-
-inline bool variantIsObject(const VariantData* var) {
-  return var && var->type == JSON_OBJECT;
-}
-
-inline bool variantIsNull(const VariantData* var) {
-  return var == 0 || var->type == JSON_NULL;
-}
-
-inline bool variantEquals(const VariantData* a, const VariantData* b) {
+inline bool variantEquals(const VariantData *a, const VariantData *b) {
   if (a == b) return true;
   if (!a || !b) return false;
-  if (a->type != b->type) return false;
-
-  switch (a->type) {
-    case JSON_LINKED_STRING:
-    case JSON_OWNED_STRING:
-      return !strcmp(a->content.asString, b->content.asString);
-
-    case JSON_LINKED_RAW:
-    case JSON_OWNED_RAW:
-      return a->content.asRaw.size == b->content.asRaw.size &&
-             !memcmp(a->content.asRaw.data, b->content.asRaw.data,
-                     a->content.asRaw.size);
-
-    case JSON_BOOLEAN:
-    case JSON_POSITIVE_INTEGER:
-    case JSON_NEGATIVE_INTEGER:
-      return a->content.asInteger == b->content.asInteger;
-
-    case JSON_ARRAY:
-      return arrayEquals(&a->content.asArray, &b->content.asArray);
-
-    case JSON_OBJECT:
-      return objectEquals(&a->content.asObject, &b->content.asObject);
-
-    case JSON_FLOAT:
-      return a->content.asFloat == b->content.asFloat;
-
-    case JSON_NULL:
-    default:
-      return true;
-  }
+  return a->equals(*b);
 }
+
+inline bool variantIsArray(const VariantData *var) {
+  return var && var->isArray();
+}
+
+inline bool variantIsBoolean(const VariantData *var) {
+  return var && var->isBoolean();
+}
+
+inline bool variantIsInteger(const VariantData *var) {
+  return var && var->isInteger();
+}
+
+inline bool variantIsFloat(const VariantData *var) {
+  return var && var->isFloat();
+}
+
+inline bool variantIsString(const VariantData *var) {
+  return var && var->isString();
+}
+
+inline bool variantIsObject(const VariantData *var) {
+  return var && var->isObject();
+}
+
+inline bool variantIsNull(const VariantData *var) {
+  return var == 0 || var->isNull();
+}
+
+inline bool variantSetBoolean(VariantData *var, bool value) {
+  if (!var) return false;
+  var->setBoolean(value);
+  return true;
+}
+
+inline bool variantSetFloat(VariantData *var, Float value) {
+  if (!var) return false;
+  var->setFloat(value);
+  return true;
+}
+
+inline bool variantSetLinkedRaw(VariantData *var,
+                                SerializedValue<const char *> value) {
+  if (!var) return false;
+  var->setLinkedRaw(value);
+  return true;
+}
+
+template <typename T>
+inline bool variantSetOwnedRaw(VariantData *var, SerializedValue<T> value,
+                               MemoryPool *pool) {
+  return var != 0 && var->setOwnedRaw(value, pool);
+}
+
+template <typename T>
+inline bool variantSetSignedInteger(VariantData *var, T value) {
+  if (!var) return false;
+  var->setSignedInteger(value);
+  return true;
+}
+
+inline bool variantSetLinkedString(VariantData *var, const char *value) {
+  if (!var) return false;
+  var->setLinkedString(value);
+  return true;
+}
+
+inline void variantSetNull(VariantData *var) {
+  if (!var) return;
+  var->setNull();
+}
+
+inline bool variantSetOwnedString(VariantData *var, char *value) {
+  if (!var) return false;
+  var->setOwnedString(value);
+  return true;
+}
+
+template <typename T>
+inline bool variantSetOwnedString(VariantData *var, T value, MemoryPool *pool) {
+  return var != 0 && var->setOwnedString(value, pool);
+}
+
+inline bool variantSetUnsignedInteger(VariantData *var, UInt value) {
+  if (!var) return false;
+  var->setUnsignedInteger(value);
+  return true;
+}
+
+inline size_t variantSize(const VariantData *var) {
+  return var != 0 ? var->size() : 0;
+}
+
+inline CollectionData *variantToArray(VariantData *var) {
+  if (!var) return 0;
+  return &var->toArray();
+}
+
+inline CollectionData *variantToObject(VariantData *var) {
+  if (!var) return 0;
+  return &var->toObject();
+}
+
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Variant/VariantImpl.hpp b/src/ArduinoJson/Variant/VariantImpl.hpp
index d808bf22..e5e53d21 100644
--- a/src/ArduinoJson/Variant/VariantImpl.hpp
+++ b/src/ArduinoJson/Variant/VariantImpl.hpp
@@ -13,6 +13,53 @@
 
 namespace ARDUINOJSON_NAMESPACE {
 
+template <typename T>
+inline T VariantData::asIntegral() const {
+  switch (type()) {
+    case VALUE_IS_POSITIVE_INTEGER:
+    case VALUE_IS_BOOLEAN:
+      return T(_content.asInteger);
+    case VALUE_IS_NEGATIVE_INTEGER:
+      return T(~_content.asInteger + 1);
+    case VALUE_IS_LINKED_STRING:
+    case VALUE_IS_OWNED_STRING:
+      return parseInteger<T>(_content.asString);
+    case VALUE_IS_FLOAT:
+      return T(_content.asFloat);
+    default:
+      return 0;
+  }
+}
+
+// T = float/double
+template <typename T>
+inline T VariantData::asFloat() const {
+  switch (type()) {
+    case VALUE_IS_POSITIVE_INTEGER:
+    case VALUE_IS_BOOLEAN:
+      return static_cast<T>(_content.asInteger);
+    case VALUE_IS_NEGATIVE_INTEGER:
+      return -static_cast<T>(_content.asInteger);
+    case VALUE_IS_LINKED_STRING:
+    case VALUE_IS_OWNED_STRING:
+      return parseFloat<T>(_content.asString);
+    case VALUE_IS_FLOAT:
+      return static_cast<T>(_content.asFloat);
+    default:
+      return 0;
+  }
+}
+
+inline const char* VariantData::asString() const {
+  switch (type()) {
+    case VALUE_IS_LINKED_STRING:
+    case VALUE_IS_OWNED_STRING:
+      return _content.asString;
+    default:
+      return 0;
+  }
+}
+
 inline bool VariantRef::set(ArrayRef array) const {
   return to<ArrayRef>().copyFrom(array);
 }
@@ -31,35 +78,35 @@ inline bool VariantRef::set(const ObjectSubscript<TString>& value) const {
 }
 
 inline bool VariantRef::set(VariantConstRef value) const {
-  return variantCopy(_data, value._data, _memoryPool);
+  return variantCopyFrom(_data, value._data, _pool);
 }
 
 inline bool VariantRef::set(VariantRef value) const {
-  return variantCopy(_data, value._data, _memoryPool);
+  return variantCopyFrom(_data, value._data, _pool);
 }
 
 template <typename T>
 inline typename enable_if<is_same<T, ArrayRef>::value, T>::type VariantRef::as()
     const {
-  return ArrayRef(_memoryPool, variantAsArray(_data));
+  return ArrayRef(_pool, _data != 0 ? _data->asArray() : 0);
 }
 
 template <typename T>
 inline typename enable_if<is_same<T, ObjectRef>::value, T>::type
 VariantRef::as() const {
-  return ObjectRef(_memoryPool, variantAsObject(_data));
+  return ObjectRef(_pool, variantAsObject(_data));
 }
 
 template <typename T>
 inline typename enable_if<is_same<T, ArrayRef>::value, ArrayRef>::type
 VariantRef::to() const {
-  return ArrayRef(_memoryPool, variantToArray(_data));
+  return ArrayRef(_pool, variantToArray(_data));
 }
 
 template <typename T>
 typename enable_if<is_same<T, ObjectRef>::value, ObjectRef>::type
 VariantRef::to() const {
-  return ObjectRef(_memoryPool, variantToObject(_data));
+  return ObjectRef(_pool, variantToObject(_data));
 }
 
 template <typename T>
@@ -69,50 +116,8 @@ VariantRef::to() const {
   return *this;
 }
 
-template <typename Visitor>
-inline void VariantRef::accept(Visitor& visitor) const {
-  return VariantConstRef(_data).accept(visitor);
-}
-
-template <typename Visitor>
-inline void VariantConstRef::accept(Visitor& visitor) const {
-  if (!_data) return visitor.visitNull();
-
-  switch (_data->type) {
-    case JSON_FLOAT:
-      return visitor.visitFloat(_data->content.asFloat);
-
-    case JSON_ARRAY:
-      return visitor.visitArray(ArrayConstRef(&_data->content.asArray));
-
-    case JSON_OBJECT:
-      return visitor.visitObject(ObjectConstRef(&_data->content.asObject));
-
-    case JSON_LINKED_STRING:
-    case JSON_OWNED_STRING:
-      return visitor.visitString(_data->content.asString);
-
-    case JSON_OWNED_RAW:
-    case JSON_LINKED_RAW:
-      return visitor.visitRawJson(_data->content.asRaw.data,
-                                  _data->content.asRaw.size);
-
-    case JSON_NEGATIVE_INTEGER:
-      return visitor.visitNegativeInteger(_data->content.asInteger);
-
-    case JSON_POSITIVE_INTEGER:
-      return visitor.visitPositiveInteger(_data->content.asInteger);
-
-    case JSON_BOOLEAN:
-      return visitor.visitBoolean(_data->content.asInteger != 0);
-
-    default:
-      return visitor.visitNull();
-  }
-}
-
 inline VariantConstRef VariantConstRef::operator[](size_t index) const {
-  return ArrayConstRef(variantAsArray(_data))[index];
+  return ArrayConstRef(_data != 0 ? _data->asArray() : 0)[index];
 }
 
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Variant/VariantRef.hpp b/src/ArduinoJson/Variant/VariantRef.hpp
index 77a768af..01ba5dff 100644
--- a/src/ArduinoJson/Variant/VariantRef.hpp
+++ b/src/ArduinoJson/Variant/VariantRef.hpp
@@ -14,7 +14,6 @@
 #include "../Operators/VariantOperators.hpp"
 #include "../Polyfills/type_traits.hpp"
 #include "VariantAs.hpp"
-#include "VariantData.hpp"
 #include "VariantFunctions.hpp"
 #include "VariantRef.hpp"
 
@@ -58,7 +57,7 @@ class VariantRefBase {
   template <typename T>
   FORCE_INLINE typename enable_if<is_same<T, bool>::value, bool>::type is()
       const {
-    return _data && _data->type == JSON_BOOLEAN;
+    return variantIsBoolean(_data);
   }
   //
   // bool is<const char*>() const;
@@ -96,13 +95,8 @@ class VariantRefBase {
     return variantIsNull(_data);
   }
 
-  FORCE_INLINE bool isInvalid() const {
-    return _data == 0;
-  }
-
   size_t size() const {
-    return objectSize(variantAsObject(_data)) +
-           arraySize(variantAsArray(_data));
+    return variantSize(_data);
   }
 
  protected:
@@ -125,11 +119,11 @@ class VariantRef : public VariantRefBase<VariantData>,
 
  public:
   // Intenal use only
-  FORCE_INLINE VariantRef(MemoryPool *memoryPool, VariantData *data)
-      : base_type(data), _memoryPool(memoryPool) {}
+  FORCE_INLINE VariantRef(MemoryPool *pool, VariantData *data)
+      : base_type(data), _pool(pool) {}
 
   // Creates an uninitialized VariantRef
-  FORCE_INLINE VariantRef() : base_type(0), _memoryPool(0) {}
+  FORCE_INLINE VariantRef() : base_type(0), _pool(0) {}
 
   // set(bool value)
   FORCE_INLINE bool set(bool value) const {
@@ -180,7 +174,7 @@ class VariantRef : public VariantRefBase<VariantData>,
   FORCE_INLINE bool set(
       SerializedValue<T> value,
       typename enable_if<!is_same<const char *, T>::value>::type * = 0) const {
-    return variantSetOwnedRaw(_data, value, _memoryPool);
+    return variantSetOwnedRaw(_data, value, _pool);
   }
 
   // set(const std::string&)
@@ -189,28 +183,20 @@ class VariantRef : public VariantRefBase<VariantData>,
   FORCE_INLINE bool set(
       const T &value,
       typename enable_if<IsString<T>::value>::type * = 0) const {
-    return variantSetString(_data, makeString(value), _memoryPool);
+    return variantSetOwnedString(_data, makeString(value), _pool);
   }
 
   // set(char*)
+  // set(const __FlashStringHelper*)
   template <typename T>
   FORCE_INLINE bool set(
       T *value, typename enable_if<IsString<T *>::value>::type * = 0) const {
-    return variantSetString(_data, makeString(value), _memoryPool);
+    return variantSetOwnedString(_data, makeString(value), _pool);
   }
 
   // set(const char*);
   FORCE_INLINE bool set(const char *value) const {
-    return variantSetString(_data, value);
-  }
-
-  // for internal use only
-  FORCE_INLINE bool set(StringInMemoryPool value) const {
-    return variantSetOwnedString(_data,
-                                 value.save(_memoryPool));  // TODO: remove?
-  }
-  FORCE_INLINE bool set(ZeroTerminatedRamStringConst value) const {
-    return variantSetString(_data, value.c_str());
+    return variantSetLinkedString(_data, value);
   }
 
   bool set(VariantConstRef value) const;
@@ -255,7 +241,9 @@ class VariantRef : public VariantRefBase<VariantData>,
   }
 
   template <typename Visitor>
-  void accept(Visitor &visitor) const;
+  void accept(Visitor &visitor) const {
+    variantAccept(_data, visitor);
+  }
 
   FORCE_INLINE bool operator==(VariantRef lhs) const {
     return variantEquals(_data, lhs._data);
@@ -281,7 +269,7 @@ class VariantRef : public VariantRefBase<VariantData>,
       const;
 
  private:
-  MemoryPool *_memoryPool;
+  MemoryPool *_pool;
 };
 
 class VariantConstRef : public VariantRefBase<const VariantData>,
@@ -296,7 +284,9 @@ class VariantConstRef : public VariantRefBase<const VariantData>,
   VariantConstRef(VariantRef var) : base_type(var._data) {}
 
   template <typename Visitor>
-  void accept(Visitor &visitor) const;
+  void accept(Visitor &visitor) const {
+    variantAccept(_data, visitor);
+  }
 
   // Get the variant as the specified type.
   //
@@ -323,7 +313,8 @@ class VariantConstRef : public VariantRefBase<const VariantData>,
   FORCE_INLINE
       typename enable_if<IsString<TString *>::value, VariantConstRef>::type
       operator[](TString *key) const {
-    return VariantConstRef(objectGet(variantAsObject(_data), makeString(key)));
+    const CollectionData *obj = variantAsObject(_data);
+    return VariantConstRef(obj ? obj->get(makeString(key)) : 0);
   }
 };
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Variant/VariantSlot.hpp b/src/ArduinoJson/Variant/VariantSlot.hpp
index 5ffcfd78..8264fa6e 100644
--- a/src/ArduinoJson/Variant/VariantSlot.hpp
+++ b/src/ArduinoJson/Variant/VariantSlot.hpp
@@ -5,7 +5,9 @@
 #pragma once
 
 #include "../Polyfills/type_traits.hpp"
-#include "../Variant/VariantData.hpp"
+#include "../Variant/VariantContent.hpp"
+
+#include <stdint.h>  // int8_t, int16_t
 
 namespace ARDUINOJSON_NAMESPACE {
 
@@ -16,8 +18,7 @@ class VariantSlot {
   // we cannot use composition because it adds padding
   // (+20% on ESP8266 for example)
   VariantContent _content;
-  bool _keyIsOwned : 1;
-  VariantType _type : 7;
+  uint8_t _flags;
   VariantSlotDiff _next;
   const char* _key;
 
@@ -28,23 +29,23 @@ class VariantSlot {
   // - no virtual
   // - no inheritance
 
-  VariantData* getData() {
+  VariantData* data() {
     return reinterpret_cast<VariantData*>(&_content);
   }
 
-  const VariantData* getData() const {
+  const VariantData* data() const {
     return reinterpret_cast<const VariantData*>(&_content);
   }
 
-  VariantSlot* getNext() {
+  VariantSlot* next() {
     return _next ? this + _next : 0;
   }
 
-  const VariantSlot* getNext() const {
-    return const_cast<VariantSlot*>(this)->getNext();
+  const VariantSlot* next() const {
+    return const_cast<VariantSlot*>(this)->next();
   }
 
-  VariantSlot* getNext(size_t distance) {
+  VariantSlot* next(size_t distance) {
     VariantSlot* slot = this;
     while (distance--) {
       if (!slot->_next) return 0;
@@ -53,29 +54,26 @@ class VariantSlot {
     return slot;
   }
 
-  VariantSlot* getPrev(VariantSlot* head) {
-    while (head) {
-      VariantSlot* nxt = head->getNext();
-      if (nxt == this) return head;
-      head = nxt;
-    }
-    return head;
-  }
-
-  const VariantSlot* getNext(size_t distance) const {
-    return const_cast<VariantSlot*>(this)->getNext(distance);
+  const VariantSlot* next(size_t distance) const {
+    return const_cast<VariantSlot*>(this)->next(distance);
   }
 
   void setNext(VariantSlot* slot) {
     _next = VariantSlotDiff(slot ? slot - this : 0);
   }
 
-  void attachTo(VariantSlot* tail) {
-    tail->_next = VariantSlotDiff(this - tail);
+  void setNextNotNull(VariantSlot* slot) {
+    ARDUINOJSON_ASSERT(slot != 0);
+    _next = VariantSlotDiff(slot - this);
   }
 
-  void setKey(const char* k, bool owned) {
-    _keyIsOwned = owned;
+  void setOwnedKey(const char* k) {
+    _flags |= KEY_IS_OWNED;
+    _key = k;
+  }
+
+  void setLinkedKey(const char* k) {
+    _flags &= VALUE_MASK;
     _key = k;
   }
 
@@ -84,13 +82,13 @@ class VariantSlot {
   }
 
   bool ownsKey() const {
-    return _keyIsOwned;
+    return (_flags & KEY_IS_OWNED) != 0;
   }
 
-  void init() {
+  void clear() {
     _next = 0;
-    _type = JSON_NULL;
-    _keyIsOwned = false;
+    _flags = 0;
+    _key = 0;
   }
 };
 
diff --git a/test/JsonArray/equals.cpp b/test/JsonArray/equals.cpp
index b7ca9e97..9559933e 100644
--- a/test/JsonArray/equals.cpp
+++ b/test/JsonArray/equals.cpp
@@ -22,7 +22,25 @@ TEST_CASE("JsonArray::operator==()") {
     REQUIRE_FALSE(array1c == array2c);
   }
 
-  SECTION("should return false when arrays differ") {
+  SECTION("should return false when LHS has more elements") {
+    array1.add(1);
+    array1.add(2);
+    array2.add(1);
+
+    REQUIRE_FALSE(array1 == array2);
+    REQUIRE_FALSE(array1c == array2c);
+  }
+
+  SECTION("should return false when RKS has more elements") {
+    array1.add(1);
+    array2.add(1);
+    array2.add(2);
+
+    REQUIRE_FALSE(array1 == array2);
+    REQUIRE_FALSE(array1c == array2c);
+  }
+
+  SECTION("should return true when arrays equal") {
     array1.add("coucou");
     array2.add("coucou");
 
diff --git a/test/JsonObject/equals.cpp b/test/JsonObject/equals.cpp
index 0d49a289..41d3d46a 100644
--- a/test/JsonObject/equals.cpp
+++ b/test/JsonObject/equals.cpp
@@ -22,7 +22,25 @@ TEST_CASE("JsonObject::operator==()") {
     REQUIRE_FALSE(obj1c == obj2c);
   }
 
-  SECTION("should return false when objs differ") {
+  SECTION("should return false when LHS has more elements") {
+    obj1["hello"] = "coucou";
+    obj1["world"] = 666;
+    obj2["hello"] = "coucou";
+
+    REQUIRE_FALSE(obj1 == obj2);
+    REQUIRE_FALSE(obj1c == obj2c);
+  }
+
+  SECTION("should return false when RKS has more elements") {
+    obj1["hello"] = "coucou";
+    obj2["hello"] = "coucou";
+    obj2["world"] = 666;
+
+    REQUIRE_FALSE(obj1 == obj2);
+    REQUIRE_FALSE(obj1c == obj2c);
+  }
+
+  SECTION("should return true when objs equal") {
     obj1["hello"] = "world";
     obj1["anwser"] = 42;
     // insert in different order
diff --git a/test/MemoryPool/StringBuilder.cpp b/test/MemoryPool/StringBuilder.cpp
index 0fc9b02b..ced1a600 100644
--- a/test/MemoryPool/StringBuilder.cpp
+++ b/test/MemoryPool/StringBuilder.cpp
@@ -12,30 +12,30 @@ static char buffer[4096];
 
 TEST_CASE("StringBuilder") {
   SECTION("Works when buffer is big enough") {
-    MemoryPool memoryPool(buffer, addPadding(JSON_STRING_SIZE(6)));
+    MemoryPool pool(buffer, addPadding(JSON_STRING_SIZE(6)));
 
-    StringBuilder str(&memoryPool);
+    StringBuilder str(&pool);
     str.append("hello");
 
-    REQUIRE(str.complete().equals("hello"));
+    REQUIRE(str.complete() == std::string("hello"));
   }
 
   SECTION("Returns null when too small") {
-    MemoryPool memoryPool(buffer, sizeof(void*));
+    MemoryPool pool(buffer, sizeof(void*));
 
-    StringBuilder str(&memoryPool);
+    StringBuilder str(&pool);
     str.append("hello world!");
 
-    REQUIRE(str.complete().isNull());
+    REQUIRE(str.complete() == 0);
   }
 
   SECTION("Increases size of memory pool") {
-    MemoryPool memoryPool(buffer, addPadding(JSON_STRING_SIZE(6)));
+    MemoryPool pool(buffer, addPadding(JSON_STRING_SIZE(6)));
 
-    StringBuilder str(&memoryPool);
+    StringBuilder str(&pool);
     str.append('h');
     str.complete();
 
-    REQUIRE(JSON_STRING_SIZE(2) == memoryPool.size());
+    REQUIRE(JSON_STRING_SIZE(2) == pool.size());
   }
 }
diff --git a/test/MemoryPool/clear.cpp b/test/MemoryPool/clear.cpp
index aff70485..51bf5ed2 100644
--- a/test/MemoryPool/clear.cpp
+++ b/test/MemoryPool/clear.cpp
@@ -11,21 +11,21 @@ static const size_t poolCapacity = 512;
 
 TEST_CASE("MemoryPool::clear()") {
   char buffer[poolCapacity];
-  MemoryPool memoryPool(buffer, sizeof(buffer));
+  MemoryPool pool(buffer, sizeof(buffer));
 
   SECTION("Discards allocated variants") {
-    memoryPool.allocVariant();
+    pool.allocVariant();
 
-    memoryPool.clear();
-    REQUIRE(memoryPool.size() == 0);
+    pool.clear();
+    REQUIRE(pool.size() == 0);
   }
 
   SECTION("Discards allocated strings") {
-    memoryPool.allocFrozenString(10);
-    REQUIRE(memoryPool.size() > 0);
+    pool.allocFrozenString(10);
+    REQUIRE(pool.size() > 0);
 
-    memoryPool.clear();
+    pool.clear();
 
-    REQUIRE(memoryPool.size() == 0);
+    REQUIRE(pool.size() == 0);
   }
 }
diff --git a/test/MemoryPool/size.cpp b/test/MemoryPool/size.cpp
index 96e5ff6b..2e277af8 100644
--- a/test/MemoryPool/size.cpp
+++ b/test/MemoryPool/size.cpp
@@ -11,48 +11,48 @@ char buffer[4096];
 
 TEST_CASE("MemoryPool::capacity()") {
   const size_t capacity = 64;
-  MemoryPool memoryPool(buffer, capacity);
-  REQUIRE(capacity == memoryPool.capacity());
+  MemoryPool pool(buffer, capacity);
+  REQUIRE(capacity == pool.capacity());
 }
 
 TEST_CASE("MemoryPool::size()") {
-  MemoryPool memoryPool(buffer, sizeof(buffer));
+  MemoryPool pool(buffer, sizeof(buffer));
 
   SECTION("Initial size is 0") {
-    REQUIRE(0 == memoryPool.size());
+    REQUIRE(0 == pool.size());
   }
 
   SECTION("size() == capacity() after allocExpandableString()") {
-    memoryPool.allocExpandableString();
-    REQUIRE(memoryPool.size() == memoryPool.capacity());
+    pool.allocExpandableString();
+    REQUIRE(pool.size() == pool.capacity());
   }
 
   SECTION("Decreases after freezeString()") {
-    StringSlot a = memoryPool.allocExpandableString();
-    memoryPool.freezeString(a, 1);
-    REQUIRE(memoryPool.size() == JSON_STRING_SIZE(1));
+    StringSlot a = pool.allocExpandableString();
+    pool.freezeString(a, 1);
+    REQUIRE(pool.size() == JSON_STRING_SIZE(1));
 
-    StringSlot b = memoryPool.allocExpandableString();
-    memoryPool.freezeString(b, 1);
-    REQUIRE(memoryPool.size() == 2 * JSON_STRING_SIZE(1));
+    StringSlot b = pool.allocExpandableString();
+    pool.freezeString(b, 1);
+    REQUIRE(pool.size() == 2 * JSON_STRING_SIZE(1));
   }
 
   SECTION("Increases after allocFrozenString()") {
-    memoryPool.allocFrozenString(0);
-    REQUIRE(memoryPool.size() == JSON_STRING_SIZE(0));
+    pool.allocFrozenString(0);
+    REQUIRE(pool.size() == JSON_STRING_SIZE(0));
 
-    memoryPool.allocFrozenString(0);
-    REQUIRE(memoryPool.size() == 2 * JSON_STRING_SIZE(0));
+    pool.allocFrozenString(0);
+    REQUIRE(pool.size() == 2 * JSON_STRING_SIZE(0));
   }
 
   SECTION("Doesn't grow when memory pool is full") {
     const size_t variantCount = sizeof(buffer) / sizeof(VariantSlot);
 
-    for (size_t i = 0; i < variantCount; i++) memoryPool.allocVariant();
-    size_t size = memoryPool.size();
+    for (size_t i = 0; i < variantCount; i++) pool.allocVariant();
+    size_t size = pool.size();
 
-    memoryPool.allocVariant();
+    pool.allocVariant();
 
-    REQUIRE(size == memoryPool.size());
+    REQUIRE(size == pool.size());
   }
 }