package eol import ( "io" "sourcecode.social/reiver/go-opt" ) // ReadEOL tries to read an end-of-line sequence. // // The end-of-line sequences it supports are: // // line-feed (LF) (U+000A) ('\n') // carriage-return (CR) (U+000D) ('\r') // carriage-return, line-feed ("\r\n") // next-line (NEL) (U+0085) // line-separator (LS) (U+2028) // // If successful, ReadEOL return the end-of-line sequence it found and the number-of-bytes read (to read in end-of-line sequence it found). // // Example usage: /// // eolSequence, size: err := eol.ReadEOL(runescanner) func ReadEOL(runescanner io.RuneScanner) (endofline string, size int, err error) { if nil == runescanner { return "", 0, errNilRuneScanner } var r0 rune var size0 int { var err error r0, size0, err = runescanner.ReadRune() if nil != err { const characterNumber uint64 = 1 var eolSequence opt.Optional[string] // = opt.Nothing[string]() // i.e., unknown var circumstance internalCircumstance = specifyCircumstance(eolSequence, characterNumber) return "", size0, errProblemReadingRune(circumstance, err) } } switch r0 { case lf: return LF, size0, nil case cr: // Nothing here. case nel: return NEL, size0, nil case ls: return LS, size0, nil default: err := runescanner.UnreadRune() if nil != err { const characterNumber uint64 = 1 var eolSequence opt.Optional[string] // = opt.Nothing[string]() // i.e., unknown var circumstance internalCircumstance = specifyCircumstance(eolSequence, characterNumber) return "", size0, errProblemUnreadingRune(circumstance, err, r0) } return "", 0, errNotEOL(r0) } // if we got here, then we had a CR var r1 rune var size1 int { var err error r1, size1, err = runescanner.ReadRune() if io.EOF == err { return CR, size0, nil } if nil != err { const characterNumber uint64 = 2 var eolSequence opt.Optional[string] // = opt.Nothing[string]() // i.e., unknown var circumstance internalCircumstance = specifyCircumstance(eolSequence, characterNumber) return "", size1+size0, errProblemReadingRune(circumstance, err) } } switch r1 { case lf: return CRLF, size1+size0, nil default: err := runescanner.UnreadRune() if nil != err { const characterNumber uint64 = 2 var eolSequence opt.Optional[string] // = opt.Nothing[string]() // i.e., unknown var circumstance internalCircumstance = specifyCircumstance(eolSequence, characterNumber) return "", size1+size0, errProblemUnreadingRune(circumstance, err, r1) } return CR, size0, nil } }