Allow using `BufferSearch` without callback

* Allow callback to be an empty `std::function`
* Add function to access result

io/buffersearch.cpp

@@ -48,7 +48,9 @@ const std::string_view::value_type *BufferSearch::process(const std::string_view
                 }
             }
             if (m_hasResult) {
-                m_callback(*this, std::move(m_result));
+                if (m_callback) {
+                    m_callback(*this, std::move(m_result));
+                }
                 return i;
             }
             m_result += currentChar;

io/buffersearch.h

@@ -23,6 +23,8 @@ public:
     const std::string_view::value_type *process(std::string_view buffer);
     const std::string_view::value_type *process(const std::string_view::value_type *buffer, std::size_t bufferSize);
     void reset();
+    std::string &result();
+    const std::string &result() const;
 
 private:
     const std::string_view m_searchTerm;
@@ -79,6 +81,22 @@ inline const std::string_view::value_type *BufferSearch::process(std::string_vie
     return process(buffer.data(), buffer.size());
 }
 
+/*!
+ * \brief Returns the search result at this point.
+ */
+inline std::string &BufferSearch::result()
+{
+    return m_result;
+}
+
+/*!
+ * \brief Returns the search result at this point.
+ */
+inline const std::string &BufferSearch::result() const
+{
+    return m_result;
+}
+
 } // namespace CppUtilities
 
 #endif // IOUTILITIES_BUFFER_SEARCH_H