ctmacuser / internetlines

Parse CRLF-terminated lines from raw data or other character code points

InternetLines

Parse CRLF-terminated lines from raw data or other character code points.

Installation

The library is designed to be used with the Swift Package Manager. Add this library's Git URL as a dependency to your SPM project. Otherwise, manually add the files in the "Sources/InternetLines/" sub-directory to your project.

Usage

The main support type is LineTerminatorSearchTargets, which specifies which line-breaking sequences should be searched for. It's an OptionSet, so multiple sequences can be searched for at once. The current search targets are:

• CRLF, carriage-return followed by line-feed: The terminator used for text lines passed along for various Internet protocols. It's also used for text files for the Windows operating system family.
• LF, line-feed only: The terminator used for text files for Unix (and related) operating systems.
• CR, carriage-return only: A terminator used for text files only for some ancient operating systems, like pre-NeXT macOS.
• CRCRLF, two carriage-returns and a line-feed: It's not an official terminator, but can appear by mistake when writing text files on Windows systems.

The main functionality is expressed through types that wrap a Sequence or Collection with the right Element type. The element type can be either UnicodeScalar or one of the default integer types. A wrapper object can be obtained through helper methods added as Sequence or Collection extensions:

• Sequence.parsedLines(considering:) returns a LineSequence, which parses then vends each line from the source sequence as a (data: [Element], terminator: [Element]), where the main part of the line is separated from the terminator upon return. At most one part of a returned tuple is empty.
• Collection.lineLocations(considering:) returns a LineLocations, which is an (optionally bi-directional) collection that vends (start: Base.Index, border: Base.Index, end: Base.Index), which is a tuple that returns the start and end of each parsed line in the source along with the border between the main part of the line and its terminator.
• Collection.lineTerminatorLocations(considering:) returns a LineTerminatorLocations, which is an (optionally bi-directional) collection that vends a Range<Base.Index> for each line-breaking sequence within the source, specifying the terminator's location.