[GitHub] [nifi-minifi-cpp] fgerlits commented on a diff in pull request #1584: MINIFICPP-1755 - Use std::span instead of gsl::span

["fgerlits (via GitHub)" <gi...@apache.org>]

fgerlits commented on code in PR #1584:
URL: https://github.com/apache/nifi-minifi-cpp/pull/1584#discussion_r1221440952


##########
libminifi/src/utils/LineByLineInputOutputStreamCallback.cpp:
##########
@@ -67,7 +67,7 @@ void LineByLineInputOutputStreamCallback::readLine() {
   if (end_of_line != input_.end()) { ++end_of_line; }
 
   current_line_ = next_line_;
-  next_line_ = utils::span_to<std::string>(gsl::make_span(&*current_pos_, &*end_of_line).as_span<char>());
+  next_line_ = utils::span_to<std::string>(utils::as_span<char>(std::span(&*current_pos_, &*end_of_line)));

Review Comment:
   I think we could remove the `&*`s:
   ```suggestion
     next_line_ = utils::span_to<std::string>(utils::as_span<char>(std::span(current_pos_, end_of_line)));
   ```
   as there is a `span` constructor which takes a pair of iterators



##########
libminifi/include/utils/gsl.h:
##########
@@ -32,18 +33,23 @@ using remove_cvref_t = typename std::remove_cv<typename std::remove_reference<T>
 }  // namespace detail
 
 template<typename Container, typename T>
-Container span_to(gsl::span<T> span) {
+Container span_to(std::span<T> span) {
   static_assert(std::is_constructible<Container, typename gsl::span<T>::iterator, typename gsl::span<T>::iterator>::value,
       "The destination container must have an iterator (pointer) range constructor");
   return Container(std::begin(span), std::end(span));
 }
 template<template<typename...> class Container, typename T>
-Container<detail::remove_cvref_t<T>> span_to(gsl::span<T> span) {
+Container<detail::remove_cvref_t<T>> span_to(std::span<T> span) {
   static_assert(std::is_constructible<Container<detail::remove_cvref_t<T>>, typename gsl::span<T>::iterator, typename gsl::span<T>::iterator>::value,
       "The destination container must have an iterator (pointer) range constructor");
   return span_to<Container<detail::remove_cvref_t<T>>>(span);
 }
 
+template<typename T, typename U>
+std::span<T> as_span(std::span<U> value) {
+  return std::span{reinterpret_cast<T*>(value.data()), value.size_bytes() / sizeof(T)};
+}

Review Comment:
   the `span_to` and `as_span` functions could be moved to a new file, eg. `utils/span.h`, as they don't belong in `gsl.h` any longer



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