enabled default constructor in WriteBatch and AsyncEngine

include/hepnos/AsyncEngine.hpp

@@ -49,6 +49,8 @@ class AsyncEngine {
 
     public:
 
+    AsyncEngine() = default;
+
     /**
      * @brief Constructor.
      *

include/hepnos/WriteBatch.hpp

@@ -52,6 +52,11 @@ class WriteBatch {
 
     public:
 
+    /**
+     * @brief Default constructor.
+     */
+    WriteBatch() = default;
+
     /**
      * @brief Constructor.
      *

src/AsyncEngine.cpp

@@ -8,11 +8,16 @@ AsyncEngine::AsyncEngine(DataStore& ds, size_t num_threads)
 : m_impl(std::make_shared<AsyncEngineImpl>(ds.m_impl, num_threads)) {}
 
 void AsyncEngine::wait() {
-    m_impl->wait();
+    if(m_impl)
+        m_impl->wait();
 }
 
 const std::vector<std::string>& AsyncEngine::errors() const {
-    return m_impl->m_errors;
+    static std::vector<std::string> _default;
+    if(m_impl)
+        return m_impl->m_errors;
+    else
+        return _default;
 }
 
 }

src/WriteBatch.cpp

@@ -18,10 +18,13 @@ WriteBatch::WriteBatch(AsyncEngine& async, unsigned max_batch_size)
 WriteBatch::~WriteBatch() {}
 
 void WriteBatch::flush() {
-    m_impl->flush();
+    if(m_impl)
+        m_impl->flush();
 }
 
 void WriteBatch::activateStatistics(bool activate) {
+    if(!m_impl)
+        throw Exception("Invalid WriteBatch");
     if(activate) {
         if(m_impl->m_stats) return;
         m_impl->m_stats = std::make_unique<WriteBatchStatistics>();
@@ -31,7 +34,8 @@ void WriteBatch::activateStatistics(bool activate) {
 }
 
 void WriteBatch::collectStatistics(WriteBatchStatistics& stats) const {
-    m_impl->collectStatistics(stats);
+    if(m_impl)
+        m_impl->collectStatistics(stats);
 }
 
 }