libdeng2: Convenience templates for Reader and Writer

(De)serializing a list of objects, and reading values using a different
type than the destination (e.g., with enums).

doomsday/libdeng2/include/de/data/reader.h

@@ -165,6 +165,40 @@ class DENG2_PUBLIC Reader
     /// Reads a serializable object from the source buffer.
     Reader &operator >> (IReadable &readable);
 
+    /**
+     * Reads a list of objects. ListType is expected to be an iterable
+     * list containing pointers to IReadable objects. The list will
+     * own the read instances.
+     *
+     * @param list  List of objects.
+     */
+    template <typename ObjectType, typename ListType>
+    Reader &readObjects(ListType &list) {
+        duint32 count;
+        *this >> count;
+        while(count-- > 0) {
+            std::auto_ptr<ObjectType> entry(new ObjectType);
+            *this >> *entry.get();
+            list.push_back(entry.release());
+        }
+        return *this;
+    }
+
+    /**
+     * Reads something from the source and converts it to another type before
+     * assigning to the destination. Use this for instance when reading an
+     * enumerated type that has been written as an integer.
+     *
+     * @param value  Value to read.
+     */
+    template <typename SerializedType, typename Type>
+    Reader &readAs(Type &value) {
+        SerializedType t;
+        *this >> t;
+        value = Type(t);
+        return *this;
+    }
+
     /**
      * Reads bytes from the source buffer until a specified delimiter value is
      * encountered. The delimiter is included as part of the read data. The end

doomsday/libdeng2/include/de/data/writer.h

@@ -168,6 +168,19 @@ class DENG2_PUBLIC Writer
     /// Writes a writable object into the destination buffer.
     Writer &operator << (IWritable const &writable);
 
+    /**
+     * Writes a list of objects. ListType is expected to be an iterable
+     * list containing pointers to IWritable objects.
+     *
+     * @param list  List of objects.
+     */
+    template <typename ListType>
+    Writer &writeObjects(ListType const &list) {
+        *this << duint32(list.size());
+        DENG2_FOR_EACH_CONST(typename ListType, i, list) *this << **i;
+        return *this;
+    }
+
     /**
      * Returns the destination byte array used by the writer.
      */