4.12 sdds::Reader creation

• name:
  Reader::open, Reader::openHeaderless, Reader::fromStdin, Reader::fromSource, Reader::fromHeaderlessSource
• description:
  Create a move-only streaming reader from a path, standard input, or caller supplied byte source. Headerless input requires a validated layout describing the data bytes. Path input with Compression::Auto selects compression from the path; custom sources require an explicit compression choice.
• synopsis:
  static sdds::Reader open(const std::filesystem::path &path,  
                           sdds::ReaderOptions options = {});  
  static sdds::Reader openHeaderless(const std::filesystem::path &path,  
                                     sdds::Layout layout,  
                                     sdds::ReaderOptions options = {});  
  static sdds::Reader fromStdin(sdds::ReaderOptions options = {});  
  static sdds::Reader fromSource(std::unique_ptr<sdds::InputSource> source,  
                                 std::string sourceName = {},  
                                 sdds::ReaderOptions options = {});  
  static sdds::Reader fromHeaderlessSource(  
      std::unique_ptr<sdds::InputSource> source, sdds::Layout layout,  
      std::string sourceName = {}, sdds::ReaderOptions options = {});

• arguments:
  • path — Input path.
  • source — Owned source adapter; ownership moves to the reader.
  • layout — Validated headerless-data layout.
  • sourceName — Diagnostic name included in error context.
  • options — Per-reader configuration and limits.
• return value:
  An open, move-only sdds::Reader. Its layout() method returns the parsed or caller-supplied layout.
• exceptions:
  sdds::IoError for source failures, sdds::FormatError for malformed headers, or another sdds::Error-derived exception with available path and byte-offset context.
• see also:
  Sections 4.11, 4.13, and 4.16.