Separate string adapter from storage policy

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