Separate string adapter from storage policy

extras/tests/Cpp17/string_view.cpp

@@ -92,10 +92,9 @@ TEST_CASE("StringViewAdapter") {
   std::string_view str("bravoXXX", 5);
   auto adapter = adaptString(str);
 
-  CHECK(adapter.compare(NULL) > 0);
-  CHECK(adapter.compare("alpha") > 0);
-  CHECK(adapter.compare("bravo") == 0);
-  CHECK(adapter.compare("charlie") < 0);
+  CHECK(stringCompare(adapter, adaptString("alpha", 5)) > 0);
+  CHECK(stringCompare(adapter, adaptString("bravo", 5)) == 0);
+  CHECK(stringCompare(adapter, adaptString("charlie", 7)) < 0);
 
   CHECK(adapter.size() == 5);
 }

extras/tests/Misc/StringAdapters.cpp

@@ -15,106 +15,75 @@
 
 using namespace ARDUINOJSON_NAMESPACE;
 
-TEST_CASE("const char*") {
+TEST_CASE("ZeroTerminatedRamString") {
   SECTION("null") {
-    StringAdapter<const char*> adapter(NULL);
+    ZeroTerminatedRamString s = adaptString(static_cast<const char*>(0));
 
-    CHECK(adapter.compare("bravo") < 0);
-    CHECK(adapter.compare(NULL) == 0);
-
-    CHECK(adapter.size() == 0);
+    CHECK(s.isNull() == true);
+    CHECK(s.size() == 0);
   }
 
   SECTION("non-null") {
-    StringAdapter<const char*> adapter("bravo");
+    ZeroTerminatedRamString s = adaptString("bravo");
 
-    CHECK(adapter.compare(NULL) > 0);
-    CHECK(adapter.compare("alpha") > 0);
-    CHECK(adapter.compare("bravo") == 0);
-    CHECK(adapter.compare("charlie") < 0);
-
-    CHECK(adapter.size() == 5);
+    CHECK(s.isNull() == false);
+    CHECK(s.size() == 5);
   }
 }
 
-TEST_CASE("const char* + size") {
+TEST_CASE("SizedRamString") {
   SECTION("null") {
-    StringAdapter<const char*, true> adapter(NULL, 10);
+    SizedRamString s = adaptString(static_cast<const char*>(0), 10);
 
-    CHECK(adapter.compare("bravo") < 0);
-    CHECK(adapter.compare(NULL) == 0);
-
-    CHECK(adapter.size() == 10);
+    CHECK(s.isNull() == true);
   }
 
   SECTION("non-null") {
-    StringAdapter<const char*, true> adapter("bravo", 5);
+    SizedRamString s = adaptString("bravo", 5);
 
-    CHECK(adapter.compare(NULL) > 0);
-    CHECK(adapter.compare("alpha") > 0);
-    CHECK(adapter.compare("bravo") == 0);
-    CHECK(adapter.compare("charlie") < 0);
-
-    CHECK(adapter.size() == 5);
+    CHECK(s.isNull() == false);
+    CHECK(s.size() == 5);
   }
 }
 
-TEST_CASE("const __FlashStringHelper*") {
+TEST_CASE("FlashString") {
   SECTION("null") {
-    StringAdapter<const __FlashStringHelper*> adapter(NULL);
+    FlashString s = adaptString(static_cast<const __FlashStringHelper*>(0));
 
-    CHECK(adapter.compare("bravo") < 0);
-    CHECK(adapter.compare(NULL) == 0);
-
-    CHECK(adapter.size() == 0);
+    CHECK(s.isNull() == true);
+    CHECK(s.size() == 0);
   }
 
   SECTION("non-null") {
-    StringAdapter<const __FlashStringHelper*> adapter = adaptString(F("bravo"));
+    FlashString s = adaptString(F("bravo"));
 
-    CHECK(adapter.compare(NULL) > 0);
-    CHECK(adapter.compare("alpha") > 0);
-    CHECK(adapter.compare("bravo") == 0);
-    CHECK(adapter.compare("charlie") < 0);
-
-    CHECK(adapter.size() == 5);
+    CHECK(s.isNull() == false);
+    CHECK(s.size() == 5);
   }
 }
 
 TEST_CASE("std::string") {
-  std::string str("bravo");
-  StringAdapter<std::string> adapter(str);
+  std::string orig("bravo");
+  SizedRamString s = adaptString(orig);
 
-  CHECK(adapter.compare(NULL) > 0);
-  CHECK(adapter.compare("alpha") > 0);
-  CHECK(adapter.compare("bravo") == 0);
-  CHECK(adapter.compare("charlie") < 0);
-
-  CHECK(adapter.size() == 5);
+  CHECK(s.isNull() == false);
+  CHECK(s.size() == 5);
 }
 
 TEST_CASE("Arduino String") {
-  ::String str("bravo");
-  StringAdapter< ::String> adapter(str);
+  ::String orig("bravo");
+  SizedRamString s = adaptString(orig);
 
-  CHECK(adapter.compare(NULL) > 0);
-  CHECK(adapter.compare("alpha") > 0);
-  CHECK(adapter.compare("bravo") == 0);
-  CHECK(adapter.compare("charlie") < 0);
-
-  CHECK(adapter.size() == 5);
+  CHECK(s.isNull() == false);
+  CHECK(s.size() == 5);
 }
 
 TEST_CASE("custom_string") {
-  custom_string str("bravo");
-  StringAdapter<custom_string> adapter(str);
+  custom_string orig("bravo");
+  SizedRamString s = adaptString(orig);
 
-  CHECK(adapter.compare(NULL) > 0);
-  CHECK(adapter.compare("alpha") > 0);
-  CHECK(adapter.compare("bravo") == 0);
-  CHECK(adapter.compare("charlie") < 0);
-
-  CHECK(adapter.size() == 5);
+  CHECK(s.isNull() == false);
+  CHECK(s.size() == 5);
 }
 
 TEST_CASE("IsString<T>") {
@@ -142,3 +111,93 @@ TEST_CASE("IsString<T>") {
     CHECK(IsString<const char[8]>::value == true);
   }
 }
+
+TEST_CASE("stringCompare") {
+  SECTION("ZeroTerminatedRamString vs ZeroTerminatedRamString") {
+    CHECK(stringCompare(adaptString("bravo"), adaptString("alpha")) > 0);
+    CHECK(stringCompare(adaptString("bravo"), adaptString("bravo")) == 0);
+    CHECK(stringCompare(adaptString("bravo"), adaptString("charlie")) < 0);
+  }
+
+  SECTION("ZeroTerminatedRamString vs SizedRamString") {
+    CHECK(stringCompare(adaptString("bravo"), adaptString("alpha?", 5)) > 0);
+    CHECK(stringCompare(adaptString("bravo"), adaptString("bravo?", 4)) > 0);
+    CHECK(stringCompare(adaptString("bravo"), adaptString("bravo?", 5)) == 0);
+    CHECK(stringCompare(adaptString("bravo"), adaptString("bravo?", 6)) < 0);
+    CHECK(stringCompare(adaptString("bravo"), adaptString("charlie?", 7)) < 0);
+  }
+
+  SECTION("SizedRamString vs SizedRamString") {
+    // clang-format off
+    CHECK(stringCompare(adaptString("bravo!", 5), adaptString("alpha?", 5)) > 0);
+    CHECK(stringCompare(adaptString("bravo!", 5), adaptString("bravo?", 5)) == 0);
+    CHECK(stringCompare(adaptString("bravo!", 5), adaptString("charlie?", 7)) < 0);
+
+    CHECK(stringCompare(adaptString("bravo!", 5), adaptString("bravo!", 4)) > 0);
+    CHECK(stringCompare(adaptString("bravo!", 5), adaptString("bravo!", 5)) == 0);
+    CHECK(stringCompare(adaptString("bravo!", 5), adaptString("bravo!", 6)) < 0);
+    // clang-format on
+  }
+
+  SECTION("FlashString vs FlashString") {
+    // clang-format off
+    CHECK(stringCompare(adaptString(F("bravo")), adaptString(F("alpha"))) > 0);
+    CHECK(stringCompare(adaptString(F("bravo")), adaptString(F("bravo"))) == 0);
+    CHECK(stringCompare(adaptString(F("bravo")), adaptString(F("charlie"))) < 0);
+    // clang-format on
+  }
+
+  SECTION("FlashString vs SizedRamString") {
+    // clang-format off
+    CHECK(stringCompare(adaptString(F("bravo")), adaptString("alpha?", 5)) > 0);
+    CHECK(stringCompare(adaptString(F("bravo")), adaptString("bravo?", 5)) == 0);
+    CHECK(stringCompare(adaptString(F("bravo")), adaptString("charlie?", 7)) < 0);
+
+    CHECK(stringCompare(adaptString(F("bravo")), adaptString("bravo!", 4)) > 0);
+    CHECK(stringCompare(adaptString(F("bravo")), adaptString("bravo!", 5)) == 0);
+    CHECK(stringCompare(adaptString(F("bravo")), adaptString("bravo!", 6)) < 0);
+    // clang-format on
+  }
+
+  SECTION("ZeroTerminatedRamString vs FlashString") {
+    // clang-format off
+    CHECK(stringCompare(adaptString("bravo"), adaptString(F("alpha?"), 5)) > 0);
+    CHECK(stringCompare(adaptString("bravo"), adaptString(F("bravo?"), 4)) > 0);
+    CHECK(stringCompare(adaptString("bravo"), adaptString(F("bravo?"), 5)) == 0);
+    CHECK(stringCompare(adaptString("bravo"), adaptString(F("bravo?"), 6)) < 0);
+    CHECK(stringCompare(adaptString("bravo"), adaptString(F("charlie?"), 7)) < 0);
+    // clang-format on
+  }
+}
+
+TEST_CASE("stringEquals()") {
+  SECTION("ZeroTerminatedRamString vs ZeroTerminatedRamString") {
+    CHECK(stringEquals(adaptString("bravo"), adaptString("brav")) == false);
+    CHECK(stringEquals(adaptString("bravo"), adaptString("bravo")) == true);
+    CHECK(stringEquals(adaptString("bravo"), adaptString("bravo!")) == false);
+  }
+
+  SECTION("ZeroTerminatedRamString vs SizedRamString") {
+    // clang-format off
+    CHECK(stringEquals(adaptString("bravo"), adaptString("bravo!", 4)) == false);
+    CHECK(stringEquals(adaptString("bravo"), adaptString("bravo!", 5)) == true);
+    CHECK(stringEquals(adaptString("bravo"), adaptString("bravo!", 6)) == false);
+    // clang-format on
+  }
+
+  SECTION("FlashString vs SizedRamString") {
+    // clang-format off
+    CHECK(stringEquals(adaptString(F("bravo")), adaptString("bravo!", 4)) == false);
+    CHECK(stringEquals(adaptString(F("bravo")), adaptString("bravo!", 5)) == true);
+    CHECK(stringEquals(adaptString(F("bravo")), adaptString("bravo!", 6)) == false);
+    // clang-format on
+  }
+
+  SECTION("SizedRamString vs SizedRamString") {
+    // clang-format off
+    CHECK(stringEquals(adaptString("bravo?", 5), adaptString("bravo!", 4)) == false);
+    CHECK(stringEquals(adaptString("bravo?", 5), adaptString("bravo!", 5)) == true);
+    CHECK(stringEquals(adaptString("bravo?", 5), adaptString("bravo!", 6)) == false);
+    // clang-format on
+  }
+}

src/ArduinoJson/Collection/CollectionData.hpp

@@ -40,14 +40,15 @@ class CollectionData {
 
   // Object only
 
-  template <typename TAdaptedString>
-  VariantData *addMember(TAdaptedString key, MemoryPool *pool);
+  template <typename TAdaptedString, typename TStoragePolicy>
+  VariantData *addMember(TAdaptedString key, MemoryPool *pool, TStoragePolicy);
 
   template <typename TAdaptedString>
   VariantData *getMember(TAdaptedString key) const;
 
-  template <typename TAdaptedString>
-  VariantData *getOrAddMember(TAdaptedString key, MemoryPool *pool);
+  template <typename TAdaptedString, typename TStoragePolicy>
+  VariantData *getOrAddMember(TAdaptedString key, MemoryPool *pool,
+                              TStoragePolicy);
 
   template <typename TAdaptedString>
   void removeMember(TAdaptedString key) {

src/ArduinoJson/Collection/CollectionImpl.hpp

@@ -5,6 +5,8 @@
 #pragma once
 
 #include <ArduinoJson/Collection/CollectionData.hpp>
+#include <ArduinoJson/Strings/StoragePolicy.hpp>
+#include <ArduinoJson/Strings/StringAdapters.hpp>
 #include <ArduinoJson/Variant/VariantData.hpp>
 
 namespace ARDUINOJSON_NAMESPACE {
@@ -34,11 +36,12 @@ inline VariantData* CollectionData::addElement(MemoryPool* pool) {
   return slotData(addSlot(pool));
 }
 
-template <typename TAdaptedString>
+template <typename TAdaptedString, typename TStoragePolicy>
 inline VariantData* CollectionData::addMember(TAdaptedString key,
-                                              MemoryPool* pool) {
+                                              MemoryPool* pool,
+                                              TStoragePolicy storage) {
   VariantSlot* slot = addSlot(pool);
-  if (!slotSetKey(slot, key, pool)) {
+  if (!slotSetKey(slot, key, pool, storage)) {
     removeSlot(slot);
     return 0;
   }
@@ -61,10 +64,8 @@ inline bool CollectionData::copyFrom(const CollectionData& src,
   for (VariantSlot* s = src._head; s; s = s->next()) {
     VariantData* var;
     if (s->key() != 0) {
-      if (s->ownsKey())
-        var = addMember(adaptString(const_cast<char*>(s->key())), pool);
-      else
-        var = addMember(adaptString(s->key()), pool);
+      String key(s->key(), !s->ownsKey());
+      var = addMember(adaptString(key), pool, getStringStoragePolicy(key));
     } else {
       var = addElement(pool);
     }
@@ -105,9 +106,11 @@ inline bool CollectionData::equalsArray(const CollectionData& other) const {
 
 template <typename TAdaptedString>
 inline VariantSlot* CollectionData::getSlot(TAdaptedString key) const {
+  if (key.isNull())
+    return 0;
   VariantSlot* slot = _head;
   while (slot) {
-    if (key.compare(slot->key()) == 0)
+    if (stringEquals(key, adaptString(slot->key())))
       break;
     slot = slot->next();
   }
@@ -137,9 +140,9 @@ inline VariantData* CollectionData::getMember(TAdaptedString key) const {
   return slot ? slot->data() : 0;
 }
 
-template <typename TAdaptedString>
-inline VariantData* CollectionData::getOrAddMember(TAdaptedString key,
-                                                   MemoryPool* pool) {
+template <typename TAdaptedString, typename TStoragePolicy>
+inline VariantData* CollectionData::getOrAddMember(
+    TAdaptedString key, MemoryPool* pool, TStoragePolicy storage_policy) {
   // ignore null key
   if (key.isNull())
     return 0;
@@ -149,7 +152,7 @@ inline VariantData* CollectionData::getOrAddMember(TAdaptedString key,
   if (slot)
     return slot->data();
 
-  return addMember(key, pool);
+  return addMember(key, pool, storage_policy);
 }
 
 inline VariantData* CollectionData::getElement(size_t index) const {

src/ArduinoJson/Document/JsonDocument.hpp

@@ -8,6 +8,7 @@
 #include <ArduinoJson/Memory/MemoryPool.hpp>
 #include <ArduinoJson/Object/MemberProxy.hpp>
 #include <ArduinoJson/Object/ObjectRef.hpp>
+#include <ArduinoJson/Strings/StoragePolicy.hpp>
 #include <ArduinoJson/Variant/VariantRef.hpp>
 #include <ArduinoJson/Variant/VariantTo.hpp>
 
@@ -244,14 +245,18 @@ class JsonDocument : public Visitable {
   // getOrAddMember(const __FlashStringHelper*)
   template <typename TChar>
   FORCE_INLINE VariantRef getOrAddMember(TChar* key) {
-    return VariantRef(&_pool, _data.getOrAddMember(adaptString(key), &_pool));
+    return VariantRef(&_pool,
+                      _data.getOrAddMember(adaptString(key), &_pool,
+                                           getStringStoragePolicy(key)));
   }
 
   // getOrAddMember(const std::string&)
   // getOrAddMember(const String&)
   template <typename TString>
   FORCE_INLINE VariantRef getOrAddMember(const TString& key) {
-    return VariantRef(&_pool, _data.getOrAddMember(adaptString(key), &_pool));
+    return VariantRef(&_pool,
+                      _data.getOrAddMember(adaptString(key), &_pool,
+                                           getStringStoragePolicy(key)));
   }
 
   FORCE_INLINE VariantRef addElement() {

src/ArduinoJson/Memory/MemoryPool.hpp

@@ -60,7 +60,7 @@ class MemoryPool {
   }
 
   template <typename TAdaptedString>
-  const char* saveString(const TAdaptedString& str) {
+  const char* saveString(TAdaptedString str) {
     if (str.isNull())
       return CopiedString();
 
@@ -74,7 +74,7 @@ class MemoryPool {
 
     char* newCopy = allocString(n + 1);
     if (newCopy) {
-      str.copyTo(newCopy, n);
+      stringGetChars(str, newCopy, n);
       newCopy[n] = 0;  // force null-terminator
     }
     return CopiedString(newCopy, n);
@@ -165,22 +165,11 @@ class MemoryPool {
   }
 
 #if ARDUINOJSON_ENABLE_STRING_DEDUPLICATION
-  template <typename TAdaptedString>
-  static bool stringEquals(const char* p, size_t n, const TAdaptedString& s) {
-    if (p[n])  // check terminator first
-      return false;
-    for (size_t i = 0; i < n; i++) {
-      if (p[i] != s[i])
-        return false;
-    }
-    return true;
-  }
-
   template <typename TAdaptedString>
   const char* findString(const TAdaptedString& str) const {
     size_t n = str.size();
     for (char* next = _begin; next + n < _left; ++next) {
-      if (stringEquals(next, n, str))
+      if (next[n] == '\0' && stringEquals(str, adaptString(next, n)))
         return next;
 
       // jump to next terminator

src/ArduinoJson/Object/ObjectFunctions.hpp

@@ -40,12 +40,13 @@ void objectRemove(CollectionData *obj, TAdaptedString key) {
   obj->removeMember(key);
 }
 
-template <typename TAdaptedString>
+template <typename TAdaptedString, typename TStoragePolicy>
 inline VariantData *objectGetOrAddMember(CollectionData *obj,
-                                         TAdaptedString key, MemoryPool *pool) {
+                                         TAdaptedString key, MemoryPool *pool,
+                                         TStoragePolicy storage_policy) {
   if (!obj)
     return 0;
 
-  return obj->getOrAddMember(key, pool);
+  return obj->getOrAddMember(key, pool, storage_policy);
 }
 }  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Object/ObjectRef.hpp

@@ -196,7 +196,8 @@ class ObjectRef : public ObjectRefBase<CollectionData>,
   template <typename TString>
   FORCE_INLINE VariantRef getOrAddMember(const TString& key) const {
     return VariantRef(_pool,
-                      objectGetOrAddMember(_data, adaptString(key), _pool));
+                      objectGetOrAddMember(_data, adaptString(key), _pool,
+                                           getStringStoragePolicy(key)));
   }
 
   // getOrAddMember(char*) const
@@ -205,7 +206,8 @@ class ObjectRef : public ObjectRefBase<CollectionData>,
   template <typename TChar>
   FORCE_INLINE VariantRef getOrAddMember(TChar* key) const {
     return VariantRef(_pool,
-                      objectGetOrAddMember(_data, adaptString(key), _pool));
+                      objectGetOrAddMember(_data, adaptString(key), _pool,
+                                           getStringStoragePolicy(key)));
   }
 
   FORCE_INLINE bool operator==(ObjectRef rhs) const {

src/ArduinoJson/Polyfills/pgmspace.hpp

@@ -65,6 +65,22 @@ inline int strcmp_P(const char* a, ARDUINOJSON_NAMESPACE::pgm_p b) {
 }
 #endif
 
+#ifndef memcmp_P
+inline int memcmp_P(const void* a, ARDUINOJSON_NAMESPACE::pgm_p b, size_t n) {
+  const uint8_t* p1 = reinterpret_cast<const uint8_t*>(a);
+  const char* p2 = b.address;
+  ARDUINOJSON_ASSERT(p1 != NULL);
+  ARDUINOJSON_ASSERT(p2 != NULL);
+  while (n-- > 0) {
+    uint8_t v1 = *p1++;
+    uint8_t v2 = pgm_read_byte(p2++);
+    if (v1 != v2)
+      return v1 - v2;
+  }
+  return 0;
+}
+#endif
+
 #ifndef memcpy_P
 inline void* memcpy_P(void* dst, ARDUINOJSON_NAMESPACE::pgm_p src, size_t n) {
   uint8_t* d = reinterpret_cast<uint8_t*>(dst);

src/ArduinoJson/Polyfills/safe_strcmp.hpp

@@ -1,33 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright Benoit Blanchon 2014-2021
-// MIT License
-
-#pragma once
-
-#include <ArduinoJson/Namespace.hpp>
-
-#include <stdint.h>  // int8_t
-#include <string.h>  // strcmp
-
-namespace ARDUINOJSON_NAMESPACE {
-
-inline int safe_strcmp(const char* a, const char* b) {
-  if (a == b)
-    return 0;
-  if (!a)
-    return -1;
-  if (!b)
-    return 1;
-  return strcmp(a, b);
-}
-
-inline int safe_strncmp(const char* a, const char* b, size_t n) {
-  if (a == b)
-    return 0;
-  if (!a)
-    return -1;
-  if (!b)
-    return 1;
-  return strncmp(a, b, n);
-}
-}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/ArduinoString.hpp

@@ -0,0 +1,24 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright Benoit Blanchon 2014-2021
+// MIT License
+
+#pragma once
+
+#include <Arduino.h>
+
+#include <ArduinoJson/Strings/Adapters/RamString.hpp>
+#include <ArduinoJson/Strings/IsString.hpp>
+
+namespace ARDUINOJSON_NAMESPACE {
+
+inline SizedRamString adaptString(const ::String& s) {
+  return SizedRamString(s.c_str(), s.length());
+}
+
+template <>
+struct IsString< ::String> : true_type {};
+
+template <>
+struct IsString< ::StringSumHelper> : true_type {};
+
+}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/ArduinoStringAdapter.hpp

@@ -1,56 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright Benoit Blanchon 2014-2021
-// MIT License
-
-#pragma once
-
-#include <Arduino.h>
-
-#include <ArduinoJson/Polyfills/safe_strcmp.hpp>
-#include <ArduinoJson/Strings/StoragePolicy.hpp>
-#include <ArduinoJson/Strings/StringAdapter.hpp>
-
-namespace ARDUINOJSON_NAMESPACE {
-
-template <>
-class StringAdapter< ::String> {
- public:
-  StringAdapter(const ::String& str) : _str(&str) {}
-
-  void copyTo(char* p, size_t n) const {
-    memcpy(p, _str->c_str(), n);
-  }
-
-  bool isNull() const {
-    // Arduino's String::c_str() can return NULL
-    return !_str->c_str();
-  }
-
-  int compare(const char* other) const {
-    // Arduino's String::c_str() can return NULL
-    const char* me = _str->c_str();
-    return safe_strcmp(me, other);
-  }
-
-  char operator[](size_t i) const {
-    ARDUINOJSON_ASSERT(_str != 0);
-    return _str->operator[](static_cast<unsigned int>(i));
-  }
-
-  size_t size() const {
-    return _str->length();
-  }
-
-  typedef storage_policies::store_by_copy storage_policy;
-
- private:
-  const ::String* _str;
-};
-
-template <>
-class StringAdapter< ::StringSumHelper> : public StringAdapter< ::String> {
- public:
-  StringAdapter(const ::String& s) : StringAdapter< ::String>(s) {}
-};
-
-}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/ConstRamStringAdapter.hpp

@@ -1,58 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright Benoit Blanchon 2014-2021
-// MIT License
-
-#pragma once
-
-#include <stddef.h>  // size_t
-#include <string.h>  // strcmp
-
-#include <ArduinoJson/Polyfills/assert.hpp>
-#include <ArduinoJson/Polyfills/safe_strcmp.hpp>
-#include <ArduinoJson/Strings/StoragePolicy.hpp>
-#include <ArduinoJson/Strings/StringAdapter.hpp>
-
-namespace ARDUINOJSON_NAMESPACE {
-
-template <>
-class StringAdapter<const char*> {
- public:
-  StringAdapter(const char* str = 0) : _str(str) {}
-
-  int compare(const char* other) const {
-    return safe_strcmp(_str, other);
-  }
-
-  bool isNull() const {
-    return !_str;
-  }
-
-  size_t size() const {
-    if (!_str)
-      return 0;
-    return strlen(_str);
-  }
-
-  char operator[](size_t i) const {
-    ARDUINOJSON_ASSERT(_str != 0);
-    ARDUINOJSON_ASSERT(i <= size());
-    return _str[i];
-  }
-
-  const char* data() const {
-    return _str;
-  }
-
-  typedef storage_policies::store_by_address storage_policy;
-
- protected:
-  const char* _str;
-};
-
-template <int N>
-class StringAdapter<const char[N]> : public StringAdapter<const char*> {
- public:
-  StringAdapter(const char* s) : StringAdapter<const char*>(s) {}
-};
-
-}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/FlashString.hpp

@@ -0,0 +1,80 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright Benoit Blanchon 2014-2021
+// MIT License
+
+#pragma once
+
+#include <Arduino.h>
+
+#include <ArduinoJson/Polyfills/pgmspace.hpp>
+#include <ArduinoJson/Strings/IsString.hpp>
+
+namespace ARDUINOJSON_NAMESPACE {
+
+class FlashString {
+ public:
+  static const size_t typeSortKey = 1;
+
+  FlashString(const __FlashStringHelper* str, size_t sz)
+      : _str(reinterpret_cast<const char*>(str)), _size(sz) {}
+
+  bool isNull() const {
+    return !_str;
+  }
+
+  char operator[](size_t i) const {
+    ARDUINOJSON_ASSERT(_str != 0);
+    ARDUINOJSON_ASSERT(i <= _size);
+    return static_cast<char>(pgm_read_byte(_str + i));
+  }
+
+  size_t size() const {
+    return _size;
+  }
+
+  friend bool stringEquals(FlashString a, SizedRamString b) {
+    ARDUINOJSON_ASSERT(a.typeSortKey < b.typeSortKey);
+    ARDUINOJSON_ASSERT(!a.isNull());
+    ARDUINOJSON_ASSERT(!b.isNull());
+    if (a.size() != b.size())
+      return false;
+    return ::memcmp_P(b.data(), a._str, a._size) == 0;
+  }
+
+  friend int stringCompare(FlashString a, SizedRamString b) {
+    ARDUINOJSON_ASSERT(a.typeSortKey < b.typeSortKey);
+    ARDUINOJSON_ASSERT(!a.isNull());
+    ARDUINOJSON_ASSERT(!b.isNull());
+    size_t minsize = a.size() < b.size() ? a.size() : b.size();
+    int res = ::memcmp_P(b.data(), a._str, minsize);
+    if (res)
+      return -res;
+    if (a.size() < b.size())
+      return -1;
+    if (a.size() > b.size())
+      return 1;
+    return 0;
+  }
+
+  friend void stringGetChars(FlashString s, char* p, size_t n) {
+    ARDUINOJSON_ASSERT(s.size() <= n);
+    ::memcpy_P(p, s._str, n);
+  }
+
+ private:
+  const char* _str;
+  size_t _size;
+};
+
+inline FlashString adaptString(const __FlashStringHelper* s) {
+  return FlashString(s, s ? strlen_P(reinterpret_cast<const char*>(s)) : 0);
+}
+
+inline FlashString adaptString(const __FlashStringHelper* s, size_t n) {
+  return FlashString(s, n);
+}
+
+template <>
+struct IsString<const __FlashStringHelper*> : true_type {};
+
+}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/FlashStringAdapter.hpp

@@ -1,55 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright Benoit Blanchon 2014-2021
-// MIT License
-
-#pragma once
-
-#include <ArduinoJson/Polyfills/pgmspace.hpp>
-#include <ArduinoJson/Strings/StoragePolicy.hpp>
-#include <ArduinoJson/Strings/StringAdapter.hpp>
-
-namespace ARDUINOJSON_NAMESPACE {
-
-template <>
-class StringAdapter<const __FlashStringHelper*> {
- public:
-  StringAdapter(const __FlashStringHelper* str) : _str(str) {}
-
-  int compare(const char* other) const {
-    if (!other && !_str)
-      return 0;
-    if (!_str)
-      return -1;
-    if (!other)
-      return 1;
-    return -strcmp_P(other, reinterpret_cast<const char*>(_str));
-  }
-
-  bool isNull() const {
-    return !_str;
-  }
-
-  void copyTo(char* p, size_t n) const {
-    memcpy_P(p, reinterpret_cast<const char*>(_str), n);
-  }
-
-  size_t size() const {
-    if (!_str)
-      return 0;
-    return strlen_P(reinterpret_cast<const char*>(_str));
-  }
-
-  char operator[](size_t i) const {
-    ARDUINOJSON_ASSERT(_str != 0);
-    ARDUINOJSON_ASSERT(i <= size());
-    return static_cast<char>(
-        pgm_read_byte(reinterpret_cast<const char*>(_str) + i));
-  }
-
-  typedef storage_policies::store_by_copy storage_policy;
-
- private:
-  const __FlashStringHelper* _str;
-};
-
-}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/JsonString.hpp

@@ -0,0 +1,20 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright Benoit Blanchon 2014-2021
+// MIT License
+
+#pragma once
+
+#include <ArduinoJson/Strings/Adapters/RamString.hpp>
+#include <ArduinoJson/Strings/IsString.hpp>
+#include <ArduinoJson/Strings/String.hpp>
+
+namespace ARDUINOJSON_NAMESPACE {
+
+inline SizedRamString adaptString(const String& s) {
+  return SizedRamString(s.c_str(), s.size());
+}
+
+template <>
+struct IsString<String> : true_type {};
+
+}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/JsonStringAdapter.hpp

@@ -1,27 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright Benoit Blanchon 2014-2021
-// MIT License
-
-#pragma once
-
-#include <ArduinoJson/Strings/Adapters/RamStringAdapter.hpp>
-#include <ArduinoJson/Strings/String.hpp>
-
-namespace ARDUINOJSON_NAMESPACE {
-
-template <>
-class StringAdapter<String> : public StringAdapter<char*> {
- public:
-  StringAdapter(const String& str)
-      : StringAdapter<char*>(str.c_str()), _isStatic(str.isStatic()) {}
-
-  bool isStatic() const {
-    return _isStatic;
-  }
-
-  typedef storage_policies::decide_at_runtime storage_policy;
-
- private:
-  bool _isStatic;
-};
-}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/RamString.hpp

@@ -0,0 +1,119 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright Benoit Blanchon 2014-2021
+// MIT License
+
+#pragma once
+
+#include <stddef.h>  // size_t
+#include <string.h>  // strcmp
+
+#include <ArduinoJson/Polyfills/assert.hpp>
+#include <ArduinoJson/Strings/IsString.hpp>
+
+namespace ARDUINOJSON_NAMESPACE {
+
+class ZeroTerminatedRamString {
+ public:
+  static const size_t typeSortKey = 3;
+
+  ZeroTerminatedRamString(const char* str) : _str(str) {}
+
+  bool isNull() const {
+    return !_str;
+  }
+
+  size_t size() const {
+    return _str ? ::strlen(_str) : 0;
+  }
+
+  char operator[](size_t i) const {
+    ARDUINOJSON_ASSERT(_str != 0);
+    ARDUINOJSON_ASSERT(i <= size());
+    return _str[i];
+  }
+
+  const char* data() const {
+    return _str;
+  }
+
+  friend int stringCompare(ZeroTerminatedRamString a,
+                           ZeroTerminatedRamString b) {
+    ARDUINOJSON_ASSERT(!a.isNull());
+    ARDUINOJSON_ASSERT(!b.isNull());
+    return ::strcmp(a._str, b._str);
+  }
+
+  friend bool stringEquals(ZeroTerminatedRamString a,
+                           ZeroTerminatedRamString b) {
+    return stringCompare(a, b) == 0;
+  }
+
+ protected:
+  const char* _str;
+};
+
+template <>
+struct IsString<char*> : true_type {};
+
+inline ZeroTerminatedRamString adaptString(const char* s) {
+  return ZeroTerminatedRamString(s);
+}
+
+template <>
+struct IsString<unsigned char*> : true_type {};
+
+inline ZeroTerminatedRamString adaptString(const unsigned char* s) {
+  return adaptString(reinterpret_cast<const char*>(s));
+}
+
+template <>
+struct IsString<signed char*> : true_type {};
+
+inline ZeroTerminatedRamString adaptString(const signed char* s) {
+  return adaptString(reinterpret_cast<const char*>(s));
+}
+
+class SizedRamString {
+ public:
+  static const size_t typeSortKey = 2;
+
+  SizedRamString(const char* str, size_t sz) : _str(str), _size(sz) {}
+
+  bool isNull() const {
+    return !_str;
+  }
+
+  size_t size() const {
+    return _size;
+  }
+
+  char operator[](size_t i) const {
+    ARDUINOJSON_ASSERT(_str != 0);
+    ARDUINOJSON_ASSERT(i <= size());
+    return _str[i];
+  }
+
+  const char* data() const {
+    return _str;
+  }
+
+ protected:
+  const char* _str;
+  size_t _size;
+};
+
+inline SizedRamString adaptString(const char* s, size_t n) {
+  return SizedRamString(s, n);
+}
+
+template <int N>
+struct IsString<char[N]> : true_type {};
+
+template <int N>
+struct IsString<const char[N]> : true_type {};
+
+template <int N>
+inline SizedRamString adaptString(char s[N]) {
+  return SizedRamString(s, strlen(s));
+}
+}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/RamStringAdapter.hpp

@@ -1,29 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright Benoit Blanchon 2014-2021
-// MIT License
-
-#pragma once
-
-#include <ArduinoJson/Polyfills/type_traits.hpp>
-#include <ArduinoJson/Strings/StoragePolicy.hpp>
-#include <ArduinoJson/Strings/StringAdapter.hpp>
-
-namespace ARDUINOJSON_NAMESPACE {
-
-template <typename TChar>
-class StringAdapter<TChar*, false,
-                    typename enable_if<sizeof(TChar) == 1 &&
-                                       !is_same<TChar, void>::value>::type>
-    : public StringAdapter<const char*> {
- public:
-  StringAdapter(const TChar* str)
-      : StringAdapter<const char*>(reinterpret_cast<const char*>(str)) {}
-
-  void copyTo(char* p, size_t n) const {
-    memcpy(p, _str, n);
-  }
-
-  typedef ARDUINOJSON_NAMESPACE::storage_policies::store_by_copy storage_policy;
-};
-
-}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/SizedFlashStringAdapter.hpp

@@ -1,56 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright Benoit Blanchon 2014-2021
-// MIT License
-
-#pragma once
-
-#include <ArduinoJson/Namespace.hpp>
-#include <ArduinoJson/Strings/StoragePolicy.hpp>
-#include <ArduinoJson/Strings/StringAdapter.hpp>
-
-namespace ARDUINOJSON_NAMESPACE {
-
-template <>
-class StringAdapter<const __FlashStringHelper*, true> {
- public:
-  StringAdapter(const __FlashStringHelper* str, size_t sz)
-      : _str(str), _size(sz) {}
-
-  int compare(const char* other) const {
-    if (!other && !_str)
-      return 0;
-    if (!_str)
-      return -1;
-    if (!other)
-      return 1;
-    return -strncmp_P(other, reinterpret_cast<const char*>(_str), _size);
-  }
-
-  bool isNull() const {
-    return !_str;
-  }
-
-  void copyTo(char* p, size_t n) const {
-    memcpy_P(p, reinterpret_cast<const char*>(_str), n);
-  }
-
-  // TODO: not covered by the tests
-  char operator[](size_t i) const {
-    ARDUINOJSON_ASSERT(_str != 0);
-    ARDUINOJSON_ASSERT(i <= _size);
-    return static_cast<char>(
-        pgm_read_byte(reinterpret_cast<const char*>(_str) + i));
-  }
-
-  size_t size() const {
-    return _size;
-  }
-
-  typedef storage_policies::store_by_copy storage_policy;
-
- private:
-  const __FlashStringHelper* _str;
-  size_t _size;
-};
-
-}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/SizedRamStringAdapter.hpp

@@ -1,49 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright Benoit Blanchon 2014-2021
-// MIT License
-
-#pragma once
-
-#include <ArduinoJson/Namespace.hpp>
-#include <ArduinoJson/Strings/StoragePolicy.hpp>
-#include <ArduinoJson/Strings/StringAdapter.hpp>
-
-#include <string.h>  // strcmp
-
-namespace ARDUINOJSON_NAMESPACE {
-
-template <typename TChar>
-class StringAdapter<TChar*, true> {
- public:
-  StringAdapter(const char* str, size_t n) : _str(str), _size(n) {}
-
-  int compare(const char* other) const {
-    return safe_strncmp(_str, other, _size);
-  }
-
-  bool isNull() const {
-    return !_str;
-  }
-
-  void copyTo(char* p, size_t n) const {
-    memcpy(p, _str, n);
-  }
-
-  size_t size() const {
-    return _size;
-  }
-
-  char operator[](size_t i) const {
-    ARDUINOJSON_ASSERT(_str != 0);
-    ARDUINOJSON_ASSERT(i <= _size);
-    return _str[i];
-  }
-
-  typedef storage_policies::store_by_copy storage_policy;
-
- private:
-  const char* _str;
-  size_t _size;
-};
-
-}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/StdString.hpp

@@ -0,0 +1,23 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright Benoit Blanchon 2014-2021
+// MIT License
+
+#pragma once
+
+#include <ArduinoJson/Strings/Adapters/RamString.hpp>
+
+#include <string>
+
+namespace ARDUINOJSON_NAMESPACE {
+
+template <typename TCharTraits, typename TAllocator>
+inline SizedRamString adaptString(
+    const std::basic_string<char, TCharTraits, TAllocator>& s) {
+  return SizedRamString(s.c_str(), s.size());
+}
+
+template <typename TCharTraits, typename TAllocator>
+struct IsString<std::basic_string<char, TCharTraits, TAllocator> > : true_type {
+};
+
+}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/StdStringAdapter.hpp

@@ -1,51 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright Benoit Blanchon 2014-2021
-// MIT License
-
-#pragma once
-
-#include <ArduinoJson/Namespace.hpp>
-#include <ArduinoJson/Strings/StoragePolicy.hpp>
-#include <ArduinoJson/Strings/StringAdapter.hpp>
-
-#include <string>
-
-namespace ARDUINOJSON_NAMESPACE {
-
-template <typename TCharTraits, typename TAllocator>
-class StringAdapter<std::basic_string<char, TCharTraits, TAllocator> > {
- public:
-  typedef std::basic_string<char, TCharTraits, TAllocator> string_type;
-
-  StringAdapter(const string_type& str) : _str(&str) {}
-
-  void copyTo(char* p, size_t n) const {
-    memcpy(p, _str->c_str(), n);
-  }
-
-  bool isNull() const {
-    return false;
-  }
-
-  int compare(const char* other) const {
-    if (!other)
-      return 1;
-    return _str->compare(other);
-  }
-
-  char operator[](size_t i) const {
-    ARDUINOJSON_ASSERT(i <= size());
-    return _str->operator[](i);
-  }
-
-  size_t size() const {
-    return _str->size();
-  }
-
-  typedef storage_policies::store_by_copy storage_policy;
-
- private:
-  const string_type* _str;
-};
-
-}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/StringView.hpp

@@ -0,0 +1,20 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright Benoit Blanchon 2014-2021
+// MIT License
+
+#pragma once
+
+#include <ArduinoJson/Strings/Adapters/RamString.hpp>
+
+#include <string_view>
+
+namespace ARDUINOJSON_NAMESPACE {
+
+inline SizedRamString adaptString(const std::string_view& s) {
+  return SizedRamString(s.data(), s.size());
+}
+
+template <>
+struct IsString<std::string_view> : true_type {};
+
+}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/Adapters/StringViewAdapter.hpp

@@ -1,49 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright Benoit Blanchon 2014-2021
-// MIT License
-
-#pragma once
-
-#include <ArduinoJson/Namespace.hpp>
-#include <ArduinoJson/Strings/StoragePolicy.hpp>
-#include <ArduinoJson/Strings/StringAdapter.hpp>
-
-#include <string_view>
-
-namespace ARDUINOJSON_NAMESPACE {
-
-template <>
-class StringAdapter<std::string_view> {
- public:
-  StringAdapter(std::string_view str) : _str(str) {}
-
-  void copyTo(char* p, size_t n) const {
-    memcpy(p, _str.data(), n);
-  }
-
-  bool isNull() const {
-    return false;
-  }
-
-  int compare(const char* other) const {
-    if (!other)
-      return 1;
-    return _str.compare(other);
-  }
-
-  char operator[](size_t i) const {
-    ARDUINOJSON_ASSERT(i <= size());
-    return _str[i];
-  }
-
-  size_t size() const {
-    return _str.size();
-  }
-
-  typedef storage_policies::store_by_copy storage_policy;
-
- private:
-  std::string_view _str;
-};
-
-}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/IsString.hpp

@@ -0,0 +1,17 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright Benoit Blanchon 2014-2021
+// MIT License
+
+#pragma once
+
+#include <ArduinoJson/Polyfills/type_traits.hpp>
+
+namespace ARDUINOJSON_NAMESPACE {
+
+template <typename T, typename Enable = void>
+struct IsString : false_type {};
+
+template <typename TChar>
+struct IsString<const TChar*> : IsString<TChar*> {};
+
+}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/StoragePolicy.hpp

@@ -4,12 +4,56 @@
 
 #pragma once
 
+#include <ArduinoJson/Memory/MemoryPool.hpp>
+#include <ArduinoJson/Strings/StoredString.hpp>
+#include <ArduinoJson/Strings/String.hpp>
+
 namespace ARDUINOJSON_NAMESPACE {
 
-namespace storage_policies {
-struct store_by_address {};
-struct store_by_copy {};
-struct decide_at_runtime {};
-}  // namespace storage_policies
+struct LinkStringStoragePolicy {
+  template <typename TAdaptedString, typename TCallback>
+  bool store(TAdaptedString str, MemoryPool *, TCallback callback) {
+    LinkedString storedString(str.data(), str.size());
+    callback(storedString);
+    return !str.isNull();
+  }
+};
+
+struct CopyStringStoragePolicy {
+  typedef CopiedString TResult;
+
+  template <typename TAdaptedString, typename TCallback>
+  bool store(TAdaptedString str, MemoryPool *pool, TCallback callback);
+};
+
+class LinkOrCopyStringStoragePolicy : LinkStringStoragePolicy,
+                                      CopyStringStoragePolicy {
+ public:
+  LinkOrCopyStringStoragePolicy(bool link) : _link(link) {}
+
+  template <typename TAdaptedString, typename TCallback>
+  bool store(TAdaptedString str, MemoryPool *pool, TCallback callback) {
+    if (_link)
+      return LinkStringStoragePolicy::store(str, pool, callback);
+    else
+      return CopyStringStoragePolicy::store(str, pool, callback);
+  }
+
+ private:
+  bool _link;
+};
+
+template <typename T>
+inline CopyStringStoragePolicy getStringStoragePolicy(const T &) {
+  return CopyStringStoragePolicy();
+}
+
+inline LinkStringStoragePolicy getStringStoragePolicy(const char *) {
+  return LinkStringStoragePolicy();
+}
+
+inline LinkOrCopyStringStoragePolicy getStringStoragePolicy(const String &s) {
+  return LinkOrCopyStringStoragePolicy(s.isStatic());
+}
 
 }  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/StoredString.hpp

@@ -4,12 +4,9 @@
 
 #pragma once
 
-#include <ArduinoJson/Polyfills/safe_strcmp.hpp>
-#include <ArduinoJson/Strings/StoragePolicy.hpp>
-
 namespace ARDUINOJSON_NAMESPACE {
 
-template <typename TStoragePolicy>
+template <bool linked>
 class StoredString {
  public:
   StoredString() : _data(0), _size(0) {}
@@ -32,7 +29,7 @@ class StoredString {
   size_t _size;
 };
 
-typedef StoredString<storage_policies::store_by_address> LinkedString;
-typedef StoredString<storage_policies::store_by_copy> CopiedString;
+typedef StoredString<true> LinkedString;
+typedef StoredString<false> CopiedString;
 
 }  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/StringAdapter.hpp

@@ -1,32 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright Benoit Blanchon 2014-2021
-// MIT License
-
-#pragma once
-
-#include <ArduinoJson/Polyfills/type_traits.hpp>
-
-namespace ARDUINOJSON_NAMESPACE {
-
-template <typename T, bool bounded = false, typename Enable = void>
-class StringAdapter;
-
-template <typename T>
-inline StringAdapter<T, false> adaptString(const T& str) {
-  return StringAdapter<T, false>(str);
-}
-
-template <typename T>
-inline StringAdapter<T, true> adaptString(const T& str, size_t sz) {
-  return StringAdapter<T, true>(str, sz);
-}
-
-template <typename T, typename Enable = void>
-struct IsString : false_type {};
-
-template <typename T>
-struct IsString<
-    T, typename make_void<typename StringAdapter<T>::storage_policy>::type>
-    : true_type {};
-
-}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/StringAdapters.hpp

@@ -4,24 +4,85 @@
 
 #pragma once
 
-#include <ArduinoJson/Strings/Adapters/ConstRamStringAdapter.hpp>
-#include <ArduinoJson/Strings/Adapters/JsonStringAdapter.hpp>
-#include <ArduinoJson/Strings/Adapters/RamStringAdapter.hpp>
-#include <ArduinoJson/Strings/Adapters/SizedRamStringAdapter.hpp>
+#include <ArduinoJson/Polyfills/type_traits.hpp>
+#include <ArduinoJson/Strings/Adapters/JsonString.hpp>
+#include <ArduinoJson/Strings/Adapters/RamString.hpp>
 
 #if ARDUINOJSON_ENABLE_STD_STRING
-#  include <ArduinoJson/Strings/Adapters/StdStringAdapter.hpp>
+#  include <ArduinoJson/Strings/Adapters/StdString.hpp>
 #endif
 
 #if ARDUINOJSON_ENABLE_STRING_VIEW
-#  include <ArduinoJson/Strings/Adapters/StringViewAdapter.hpp>
+#  include <ArduinoJson/Strings/Adapters/StringView.hpp>
 #endif
 
 #if ARDUINOJSON_ENABLE_ARDUINO_STRING
-#  include <ArduinoJson/Strings/Adapters/ArduinoStringAdapter.hpp>
+#  include <ArduinoJson/Strings/Adapters/ArduinoString.hpp>
 #endif
 
 #if ARDUINOJSON_ENABLE_PROGMEM
-#  include <ArduinoJson/Strings/Adapters/FlashStringAdapter.hpp>
-#  include <ArduinoJson/Strings/Adapters/SizedFlashStringAdapter.hpp>
+#  include <ArduinoJson/Strings/Adapters/FlashString.hpp>
 #endif
+
+namespace ARDUINOJSON_NAMESPACE {
+
+template <typename TAdaptedString1, typename TAdaptedString2>
+typename enable_if<TAdaptedString1::typeSortKey <= TAdaptedString2::typeSortKey,
+                   int>::type
+stringCompare(TAdaptedString1 s1, TAdaptedString2 s2) {
+  ARDUINOJSON_ASSERT(!s1.isNull());
+  ARDUINOJSON_ASSERT(!s2.isNull());
+  size_t size1 = s1.size();
+  size_t size2 = s2.size();
+  size_t n = size1 < size2 ? size1 : size2;
+  for (size_t i = 0; i < n; i++) {
+    if (s1[i] != s2[i])
+      return s1[i] - s2[i];
+  }
+  if (size1 < size2)
+    return -1;
+  if (size1 > size2)
+    return 1;
+  return 0;
+}
+
+template <typename TAdaptedString1, typename TAdaptedString2>
+typename enable_if<
+    (TAdaptedString1::typeSortKey > TAdaptedString2::typeSortKey), int>::type
+stringCompare(TAdaptedString1 s1, TAdaptedString2 s2) {
+  return -stringCompare(s2, s1);
+}
+
+template <typename TAdaptedString1, typename TAdaptedString2>
+typename enable_if<TAdaptedString1::typeSortKey <= TAdaptedString2::typeSortKey,
+                   bool>::type
+stringEquals(TAdaptedString1 s1, TAdaptedString2 s2) {
+  ARDUINOJSON_ASSERT(!s1.isNull());
+  ARDUINOJSON_ASSERT(!s2.isNull());
+  size_t size1 = s1.size();
+  size_t size2 = s2.size();
+  if (size1 != size2)
+    return false;
+  for (size_t i = 0; i < size1; i++) {
+    if (s1[i] != s2[i])
+      return false;
+  }
+  return true;
+}
+
+template <typename TAdaptedString1, typename TAdaptedString2>
+typename enable_if<
+    (TAdaptedString1::typeSortKey > TAdaptedString2::typeSortKey), bool>::type
+stringEquals(TAdaptedString1 s1, TAdaptedString2 s2) {
+  return stringEquals(s2, s1);
+}
+
+template <typename TAdaptedString>
+static void stringGetChars(TAdaptedString s, char* p, size_t n) {
+  ARDUINOJSON_ASSERT(s.size() <= n);
+  for (size_t i = 0; i < n; i++) {
+    p[i] = s[i];
+  }
+}
+
+}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Variant/ConverterImpl.hpp

@@ -115,7 +115,8 @@ struct Converter<T, typename enable_if<is_floating_point<T>::value>::type> {
 template <>
 struct Converter<const char*> {
   static void toJson(const char* src, VariantRef dst) {
-    variantSetString(getData(dst), adaptString(src), getPool(dst));
+    variantSetString(getData(dst), adaptString(src), getPool(dst),
+                     getStringStoragePolicy(src));
   }
 
   static const char* fromJson(VariantConstRef src) {
@@ -132,7 +133,8 @@ struct Converter<const char*> {
 template <>
 struct Converter<String> {
   static void toJson(String src, VariantRef dst) {
-    variantSetString(getData(dst), adaptString(src), getPool(dst));
+    variantSetString(getData(dst), adaptString(src), getPool(dst),
+                     getStringStoragePolicy(src));
   }
 
   static String fromJson(VariantConstRef src) {
@@ -151,7 +153,8 @@ inline typename enable_if<IsString<T>::value, bool>::type convertToJson(
     const T& src, VariantRef dst) {
   VariantData* data = getData(dst);
   MemoryPool* pool = getPool(dst);
-  return variantSetString(data, adaptString(src), pool);
+  return variantSetString(data, adaptString(src), pool,
+                          getStringStoragePolicy(src));
 }
 
 template <>

src/ArduinoJson/Variant/SlotFunctions.hpp

@@ -9,40 +9,24 @@
 
 namespace ARDUINOJSON_NAMESPACE {
 
-template <typename TAdaptedString>
-inline bool slotSetKey(VariantSlot* var, TAdaptedString key, MemoryPool* pool) {
-  if (!var)
-    return false;
-  return slotSetKey(var, key, pool, typename TAdaptedString::storage_policy());
+struct SlotKeySetter {
+  SlotKeySetter(VariantSlot* instance) : _instance(instance) {}
+
+  template <typename TStoredString>
+  void operator()(TStoredString s) {
+    if (!s)
+      return;
+    ARDUINOJSON_ASSERT(_instance != 0);
+    _instance->setKey(s);
   }
 
-template <typename TAdaptedString>
+  VariantSlot* _instance;
+};
+
+template <typename TAdaptedString, typename TStoragePolicy>
 inline bool slotSetKey(VariantSlot* var, TAdaptedString key, MemoryPool* pool,
-                       storage_policies::decide_at_runtime) {
-  if (key.isStatic()) {
-    return slotSetKey(var, key, pool, storage_policies::store_by_address());
-  } else {
-    return slotSetKey(var, key, pool, storage_policies::store_by_copy());
-  }
-}
-
-template <typename TAdaptedString>
-inline bool slotSetKey(VariantSlot* var, TAdaptedString key, MemoryPool*,
-                       storage_policies::store_by_address) {
-  ARDUINOJSON_ASSERT(var);
-  var->setKey(LinkedString(key.data(), key.size()));
-  return true;
-}
-
-template <typename TAdaptedString>
-inline bool slotSetKey(VariantSlot* var, TAdaptedString key, MemoryPool* pool,
-                       storage_policies::store_by_copy) {
-  CopiedString dup(pool->saveString(key), key.size());
-  if (!dup)
-    return false;
-  ARDUINOJSON_ASSERT(var);
-  var->setKey(dup);
-  return true;
+                       TStoragePolicy storage) {
+  return storage.store(key, pool, SlotKeySetter(var));
 }
 
 inline size_t slotSize(const VariantSlot* var) {

src/ArduinoJson/Variant/VariantCompare.hpp

@@ -8,7 +8,7 @@
 #include <ArduinoJson/Misc/Visitable.hpp>
 #include <ArduinoJson/Numbers/arithmeticCompare.hpp>
 #include <ArduinoJson/Polyfills/type_traits.hpp>
-#include <ArduinoJson/Strings/StringAdapter.hpp>
+#include <ArduinoJson/Strings/StringAdapters.hpp>
 #include <ArduinoJson/Variant/Visitor.hpp>
 
 namespace ARDUINOJSON_NAMESPACE {
@@ -23,12 +23,12 @@ struct Comparer;
 template <typename T>
 struct Comparer<T, typename enable_if<IsString<T>::value>::type>
     : ComparerBase {
-  T rhs;
+  T rhs;  // TODO: store adapted string?
 
   explicit Comparer(T value) : rhs(value) {}
 
-  CompareResult visitString(const char *lhs, size_t) {
-    int i = adaptString(rhs).compare(lhs);
+  CompareResult visitString(const char *lhs, size_t n) {
+    int i = stringCompare(adaptString(rhs), adaptString(lhs, n));
     if (i < 0)
       return COMPARE_RESULT_GREATER;
     else if (i > 0)

src/ArduinoJson/Variant/VariantData.hpp

@@ -99,27 +99,7 @@ class VariantData {
     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 storeString(
-            adaptString(const_cast<char *>(src._content.asString.data),
-                        src._content.asString.size),
-            pool);
-      case VALUE_IS_OWNED_RAW:
-        return storeOwnedRaw(
-            serialized(src._content.asString.data, src._content.asString.size),
-            pool);
-      default:
-        setType(src.type());
-        _content = src._content;
-        return true;
-    }
-  }
+  bool copyFrom(const VariantData &src, MemoryPool *pool);
 
   bool isArray() const {
     return (_flags & VALUE_IS_ARRAY) != 0;
@@ -242,11 +222,6 @@ class VariantData {
     _content.asString.size = s.size();
   }
 
-  template <typename TAdaptedString>
-  bool storeString(TAdaptedString value, MemoryPool *pool) {
-    return storeString(value, pool, typename TAdaptedString::storage_policy());
-  }
-
   CollectionData &toArray() {
     setType(VALUE_IS_ARRAY);
     _content.asCollection.clear();
@@ -307,13 +282,14 @@ class VariantData {
     return isObject() ? _content.asCollection.getMember(key) : 0;
   }
 
-  template <typename TAdaptedString>
-  VariantData *getOrAddMember(TAdaptedString key, MemoryPool *pool) {
+  template <typename TAdaptedString, typename TStoragePolicy>
+  VariantData *getOrAddMember(TAdaptedString key, MemoryPool *pool,
+                              TStoragePolicy storage_policy) {
     if (isNull())
       toObject();
     if (!isObject())
       return 0;
-    return _content.asCollection.getOrAddMember(key, pool);
+    return _content.asCollection.getOrAddMember(key, pool, storage_policy);
   }
 
   void movePointers(ptrdiff_t stringDistance, ptrdiff_t variantDistance) {
@@ -327,46 +303,36 @@ class VariantData {
     return _flags & VALUE_MASK;
   }
 
+  template <typename TAdaptedString, typename TStoragePolicy>
+  inline bool storeString(TAdaptedString value, MemoryPool *pool,
+                          TStoragePolicy storage) {
+    if (value.isNull()) {
+      setNull();
+      return true;
+    }
+
+    return storage.store(value, pool, VariantStringSetter(this));
+  }
+
  private:
   void setType(uint8_t t) {
     _flags &= OWNED_KEY_BIT;
     _flags |= t;
   }
 
-  template <typename TAdaptedString>
-  inline bool storeString(TAdaptedString value, MemoryPool *pool,
-                          storage_policies::decide_at_runtime) {
-    if (value.isStatic())
-      return storeString(value, pool, storage_policies::store_by_address());
+  struct VariantStringSetter {
+    VariantStringSetter(VariantData *instance) : _instance(instance) {}
+
+    template <typename TStoredString>
+    void operator()(TStoredString s) {
+      if (s)
+        _instance->setString(s);
       else
-      return storeString(value, pool, storage_policies::store_by_copy());
+        _instance->setNull();
     }
 
-  template <typename TAdaptedString>
-  inline bool storeString(TAdaptedString value, MemoryPool *,
-                          storage_policies::store_by_address) {
-    if (value.isNull())
-      setNull();
-    else
-      setString(LinkedString(value.data(), value.size()));
-    return true;
-  }
-
-  template <typename TAdaptedString>
-  inline bool storeString(TAdaptedString value, MemoryPool *pool,
-                          storage_policies::store_by_copy) {
-    if (value.isNull()) {
-      setNull();
-      return true;
-    }
-    const char *copy = pool->saveString(value);
-    if (!copy) {
-      setNull();
-      return false;
-    }
-    setString(CopiedString(copy, value.size()));
-    return true;
-  }
+    VariantData *_instance;
+  };
 };
 
 }  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Variant/VariantFunctions.hpp

@@ -5,6 +5,7 @@
 #pragma once
 
 #include <ArduinoJson/Polyfills/attributes.hpp>
+#include <ArduinoJson/Strings/StoragePolicy.hpp>
 #include <ArduinoJson/Variant/VariantData.hpp>
 
 namespace ARDUINOJSON_NAMESPACE {
@@ -49,12 +50,10 @@ inline void variantSetNull(VariantData *var) {
   var->setNull();
 }
 
-template <typename TAdaptedString>
+template <typename TAdaptedString, typename TStoragePolicy>
 inline bool variantSetString(VariantData *var, TAdaptedString value,
-                             MemoryPool *pool) {
-  if (!var)
-    return false;
-  return var->storeString(value, pool);
+                             MemoryPool *pool, TStoragePolicy storage_policy) {
+  return var != 0 ? var->storeString(value, pool, storage_policy) : 0;
 }
 
 inline size_t variantSize(const VariantData *var) {
@@ -87,14 +86,18 @@ inline NO_INLINE VariantData *variantGetOrAddElement(VariantData *var,
 template <typename TChar>
 NO_INLINE VariantData *variantGetOrAddMember(VariantData *var, TChar *key,
                                              MemoryPool *pool) {
-  return var != 0 ? var->getOrAddMember(adaptString(key), pool) : 0;
+  return var != 0 ? var->getOrAddMember(adaptString(key), pool,
+                                        getStringStoragePolicy(key))
+                  : 0;
 }
 
 template <typename TString>
 NO_INLINE VariantData *variantGetOrAddMember(VariantData *var,
                                              const TString &key,
                                              MemoryPool *pool) {
-  return var != 0 ? var->getOrAddMember(adaptString(key), pool) : 0;
+  return var != 0 ? var->getOrAddMember(adaptString(key), pool,
+                                        getStringStoragePolicy(key))
+                  : 0;
 }
 
 inline bool variantIsNull(const VariantData *var) {

src/ArduinoJson/Variant/VariantImpl.hpp

@@ -81,6 +81,28 @@ inline String VariantData::asString() const {
   }
 }
 
+inline bool VariantData::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: {
+      String value = src.asString();
+      return storeString(adaptString(value), pool,
+                         getStringStoragePolicy(value));
+    }
+    case VALUE_IS_OWNED_RAW:
+      return storeOwnedRaw(
+          serialized(src._content.asString.data, src._content.asString.size),
+          pool);
+    default:
+      setType(src.type());
+      _content = src._content;
+      return true;
+  }
+}
+
 template <typename T>
 inline typename enable_if<is_same<T, ArrayRef>::value, ArrayRef>::type
 VariantRef::to() const {
@@ -146,4 +168,15 @@ inline VariantConstRef operator|(VariantConstRef preferedValue,
 inline bool VariantRef::set(char value) const {
   return set<signed char>(value);
 }
+
+// TODO: move somewhere else
+template <typename TAdaptedString, typename TCallback>
+bool CopyStringStoragePolicy::store(TAdaptedString str, MemoryPool *pool,
+                                    TCallback callback) {
+  const char *copy = pool->saveString(str);
+  CopiedString storedString(copy, str.size());
+  callback(storedString);
+  return copy != 0;
+}
+
 }  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Variant/VariantSlot.hpp

@@ -7,7 +7,6 @@
 #include <ArduinoJson/Polyfills/integer.hpp>
 #include <ArduinoJson/Polyfills/limits.hpp>
 #include <ArduinoJson/Polyfills/type_traits.hpp>
-#include <ArduinoJson/Strings/StoragePolicy.hpp>
 #include <ArduinoJson/Strings/StoredString.hpp>
 #include <ArduinoJson/Variant/VariantContent.hpp>