Added comments

include/ArduinoJson/Internals/List.hpp

@@ -13,6 +13,9 @@
 namespace ArduinoJson {
 namespace Internals {
 
+// A singly linked list of T.
+// The linked list is composed of ListNode<T>.
+// It is derived by JsonArray and JsonObject
 template <typename T>
 class List {
  public:
@@ -21,9 +24,21 @@ class List {
   typedef ListIterator<T> iterator;
   typedef ListConstIterator<T> const_iterator;
 
+  // Creates an empty List<T> attached to a JsonBuffer.
+  // The JsonBuffer allows to allocate new nodes.
+  // When buffer is NULL, the List is not able to grow and success() returns
+  // false. This is used to identify bad memory allocations and parsing
+  // failures.
   explicit List(JsonBuffer *buffer) : _buffer(buffer), _firstNode(NULL) {}
 
+  // Returns true if the object is valid
+  // Would return false in the following situation:
+  // - the memory allocation failed (StaticJsonBuffer was too small)
+  // - the JSON parsing failed
   bool success() const { return _buffer != NULL; }
+
+  // Returns the numbers of elements in the list.
+  // For a JsonObject, it would return the number of key-value pairs
   int size() const;
 
   iterator begin() { return iterator(_firstNode); }