[24616] Add context to Cdr

include/fastcdr/Cdr.h

@@ -22,6 +22,7 @@
 #include <cstring>
 #include <functional>
 #include <map>
+#include <memory>
 #include <string>
 #include <type_traits>
 #include <utility>
@@ -69,6 +70,20 @@ class Cdr
 {
 public:
 
+    /**
+     * @brief This structure represents the context of a CDR serialization.
+     *
+     * Can be used by external (de)serialization functions to customize the serialization of a type.
+     * The Cdr object can be instantiated with a shared pointer to a Context object, and a getter for the context is
+     * provided in the Cdr class so it can be accessed from the external (de)serialization functions.
+     */
+    struct Cdr_DllAPI Context
+    {
+        // Default virtual destructor to allow proper cleanup of derived classes, and to make sure the class
+        // is polymorphic so it can be used with dynamic_pointer_cast.
+        virtual ~Context() = default;
+    };
+
     /*!
      * @brief This enumeration represents endianness types.
      */
@@ -167,6 +182,21 @@ class Cdr
             const Endianness endianness = DEFAULT_ENDIAN,
             const CdrVersion cdr_version = XCDRv2);
 
+    /*!
+     * @brief This constructor creates an eprosima::fastcdr::Cdr object that can serialize/deserialize
+     * the assigned buffer with a specific context.
+     * @param cdr_buffer A reference to the buffer that contains (or will contain) the CDR representation.
+     * @param context A shared pointer to the context that will be used for serialization/deserialization.
+     * @param endianness The initial endianness that will be used. The default value is the endianness of the system.
+     * @param cdr_version Represents the type of encoding algorithm that will be used for the encoding.
+     * The default value is CdrVersion::XCDRv2.
+     */
+    Cdr_DllAPI Cdr(
+            FastBuffer& cdr_buffer,
+            const std::shared_ptr<Context>& context,
+            const Endianness endianness = DEFAULT_ENDIAN,
+            const CdrVersion cdr_version = XCDRv2);
+
     /*!
      * @brief This function reads the encapsulation of the CDR stream.
      *        If the CDR stream contains an encapsulation, then this function should be called before starting to deserialize.
@@ -235,6 +265,12 @@ class Cdr
      */
     Cdr_DllAPI Endianness endianness() const;
 
+    /*!
+     * @brief This function returns the context used by the CDR type.
+     * @return The context.
+     */
+    Cdr_DllAPI std::shared_ptr<Context> get_context() const;
+
     /*!
      * @brief This function skips a number of bytes in the CDR stream buffer.
      * @param num_bytes The number of bytes that will be jumped.
@@ -3588,6 +3624,9 @@ class Cdr
     //! Whether the encapsulation was serialized.
     bool encapsulation_serialized_ {false};
 
+    //! Custom serialization context.
+    std::shared_ptr<Context> context_;
+
 
     uint32_t get_long_lc(
             SerializedMemberSizeForNextInt serialized_member_size);

src/cpp/Cdr.cpp

@@ -14,6 +14,7 @@
 
 #include <cstring>
 #include <limits>
+#include <memory>
 
 #include <fastcdr/Cdr.h>
 
@@ -134,6 +135,15 @@ Cdr::Cdr(
         FastBuffer& cdr_buffer,
         const Endianness endianness,
         const CdrVersion cdr_version)
+    : Cdr(cdr_buffer, nullptr, endianness, cdr_version)
+{
+}
+
+Cdr::Cdr(
+        FastBuffer& cdr_buffer,
+        const std::shared_ptr<Context>& context,
+        const Endianness endianness,
+        const CdrVersion cdr_version)
     : cdr_buffer_(cdr_buffer)
     , cdr_version_(cdr_version)
     , endianness_(endianness)
@@ -142,6 +152,7 @@ Cdr::Cdr(
     , origin_(cdr_buffer.begin())
     , end_(cdr_buffer.end())
     , initial_state_(*this)
+    , context_(context)
 {
     switch (cdr_version_)
     {
@@ -263,7 +274,8 @@ Cdr& Cdr::read_encapsulation()
                 }
                 break;
             default:
-                throw BadParamException("Unexpected encoding algorithm received in Cdr::read_encapsulation for DDS CDR");
+                throw BadParamException(
+                          "Unexpected encoding algorithm received in Cdr::read_encapsulation for DDS CDR");
         }
         reset_callbacks();
 
@@ -417,6 +429,11 @@ Cdr::Endianness Cdr::endianness() const
     return static_cast<Endianness>(endianness_);
 }
 
+std::shared_ptr<Cdr::Context> Cdr::get_context() const
+{
+    return context_;
+}
+
 bool Cdr::jump(
         size_t num_bytes)
 {

versions.md

@@ -1,6 +1,9 @@
 # v2.4.0
 
+* Add context to `Cdr` class to allow for customization of external (de)serialization methods.
+
 # v2.3.0
+
 * Fix symbol visibility for exception classes
 
     `Exception` changed to be a base class without inheriting from `std::exception`.