just unfold everything beforehand and use a scanner

vcf2fritzbox.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bufio"
 	"encoding/xml"
 	"fmt"
 	"io"
@@ -11,10 +12,6 @@ import (
 	"time"
 )
 
-func complain(s string) {
-	fmt.Fprintln(os.Stderr, s)
-}
-
 func optExit(err error) {
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
@@ -22,46 +19,8 @@ func optExit(err error) {
 	}
 }
 
-// the vCard RFC says, a single logical line can be "folded" to multiple physical lines,
+func unfold(s string) string {
-// so this shit must be done
+	return strings.ReplaceAll(strings.ReplaceAll(s, "\r\n ", ""), "\r\n\t", "")
-type UnfoldingReader struct {
-	buf []byte
-	i   int
-	j   int
-}
-
-func NewUnfoldingReader(buf []byte) *UnfoldingReader {
-	return &UnfoldingReader{buf, 0, 0}
-}
-
-func replaceFold(s string) string {
-	// Yes, I know and I don't care
-	return strings.TrimSpace(strings.ReplaceAll(strings.ReplaceAll(s, "\r\n ", ""), "\r\n\t", ""))
-}
-
-func (r *UnfoldingReader) ReadLine() (string, bool) {
-	readCR := false
-	readCRLF := false
-	for r.j = r.i; r.j < len(r.buf); r.j++ {
-		if r.buf[r.j] == '\r' {
-			readCR = true
-		} else if readCR && r.buf[r.j] == '\n' {
-			readCRLF = true
-		} else if readCRLF && r.buf[r.j] != ' ' && r.buf[r.j] != '\t' {
-			break
-		} else {
-			readCRLF = false
-		}
-	}
-	var s string
-	if r.i < len(r.buf) {
-		s = replaceFold(string(r.buf[r.i:r.j]))
-	} else {
-		s = ""
-	}
-	notEOB := (r.i < len(r.buf))
-	r.i = r.j
-	return s, notEOB
 }
 
 func vCardValue(line string) string {
@@ -185,9 +144,11 @@ func (n *Number) WriteFritzboxXML(s io.Writer, i int) {
 }
 
 func GetContacts(buf []byte) (c ContactSet) {
-	r := NewUnfoldingReader(buf)
+	s := unfold(string(buf))
+	scanner := bufio.NewScanner(strings.NewReader(s))
 	var current *Contact
-	for l, ok := r.ReadLine(); ok; l, ok = r.ReadLine() {
+	for scanner.Scan() {
+		l := strings.TrimSpace(scanner.Text())
 		if l == "BEGIN:VCARD" {
 			current = &Contact{}
 		} else if l == "END:VCARD" {
@@ -197,6 +158,7 @@ func GetContacts(buf []byte) (c ContactSet) {
 			current.setValue(l)
 		}
 	}
+	optExit(scanner.Err())
 	if current != nil {
 		c = append(c, *current)
 	}