ExpectString and ExpectOneOfString implemented

errors.go

@@ -6,4 +6,5 @@ import (
 
 var (
 	ErrNothingToUnread = adverr.NewErrTmpl("ErrNothingToUnread", "Unreading failed because there wasn't any Read yet")
+	ErrNoMatchFound    = adverr.NewErrTmpl("ErrNoMatchFound", "no match found")
 )

reader.go

@@ -204,6 +204,48 @@ func (r *Reader) ExpectRune(f ...RuneFunc) (bool, error) {
 	return findFirstTrue(rn, f), nil
 }
 
+// ExpectString calls ExpectRune for each rune in str successively.
+// If the expected string was not found, all read runes will be unread
+func (r *Reader) ExpectString(str string) (bool, error) {
+	read := 0
+	for _, rn := range str {
+		ok, err := r.ExpectRune(Is(rn))
+		if err != nil {
+			return false, err
+		}
+
+		read++
+
+		if !ok {
+			if err := r.UnreadRunes(read); err != nil {
+				return false, err
+			}
+			return false, nil
+		}
+	}
+
+	return true, nil
+}
+
+// ExpectOneOfString calls ExpectString for each string successively
+// and returns the string which first matched.
+// The returned string will not be unread.
+// If no string matches, ErrNoMatchFound is returned
+func (r *Reader) ExpectOneOfString(str ...string) (string, error) {
+	for _, s := range str {
+		ok, err := r.ExpectString(s)
+		if err != nil {
+			return "", err
+		}
+
+		if ok {
+			return s, nil
+		}
+	}
+
+	return "", ErrNoMatchFound
+}
+
 // Commit clears the internal buffer and therefore removes all data which were already read.
 // After calling Commit any unreads will return ErrNothingToUnread until another read occured.
 func (r *Reader) Commit() {