VariantIterator: remove unnecessary move construction

gamgee/variant_iterator.cpp

@@ -16,22 +16,17 @@ VariantIterator::VariantIterator(vcfFile* variant_file_ptr, const std::shared_pt
   m_variant_file_ptr {variant_file_ptr},
   m_variant_header_ptr {variant_header_ptr},
   m_variant_record_ptr {utils::make_shared_variant(bcf_init1())},      ///< important to initialize the record buffer in the constructor so we can reuse it across the iterator
-  m_variant_record {fetch_next_record()}
-{}
-
-VariantIterator::VariantIterator(VariantIterator&& original) :
-  m_variant_file_ptr   {move(original.m_variant_file_ptr)},
-  m_variant_header_ptr {move(original.m_variant_header_ptr)},
-  m_variant_record_ptr {move(original.m_variant_record_ptr)},
-  m_variant_record     {move(original.m_variant_record)}
-{}
+  m_variant_record {m_variant_header_ptr, m_variant_record_ptr}
+{
+    fetch_next_record();
+}
 
 Variant& VariantIterator::operator*() {
   return m_variant_record;
 }
 
 Variant& VariantIterator::operator++() {
-  m_variant_record = fetch_next_record();
+  fetch_next_record();
   return m_variant_record;
 }
 
@@ -47,12 +42,11 @@ bool VariantIterator::empty() {
  * @brief pre-fetches the next variant record
  * @warning we're reusing the existing htslib memory, so users should be aware that all objects from the previous iteration are now stale unless a deep copy has been performed
  */
-Variant VariantIterator::fetch_next_record() {
+void VariantIterator::fetch_next_record() {
  if (bcf_read1(m_variant_file_ptr, m_variant_header_ptr.get(), m_variant_record_ptr.get()) < 0) {
     m_variant_file_ptr = nullptr;
-    return Variant{};
+    m_variant_record = Variant{};
   }
-  return Variant{m_variant_header_ptr, m_variant_record_ptr};
 }
 
 }

gamgee/variant_iterator.h

@@ -31,7 +31,12 @@ class VariantIterator {
   /**
    * @brief a VariantIterator move constructor guarantees all objects will have the same state.
    */
-  VariantIterator(VariantIterator&&);
+  VariantIterator(VariantIterator&&) = default;
+
+  /**
+   * @brief a VariantIterator move assignment operator guarantees all objects will have the same state.
+   */
+  VariantIterator& operator= (VariantIterator&&) = default;
 
   /**
    * @brief inequality operator (needed by for-each loop)
@@ -71,7 +76,7 @@ class VariantIterator {
   std::shared_ptr<bcf1_t> m_variant_record_ptr;    ///< pointer to the internal structure of the variant record. Useful to only allocate it once.
   Variant m_variant_record;                        ///< temporary record to hold between fetch (operator++) and serve (operator*)
 
-  Variant fetch_next_record();                     ///< fetches next Variant record into existing htslib memory without making a copy
+  void fetch_next_record();                        ///< fetches next Variant record into existing htslib memory without making a copy
 };
 
 }  // end namespace gamgee