positions introduced

reader.go

@@ -9,22 +9,36 @@ import (
 )
 
 type Reader struct {
-	buf *dstruct.Stack[rune]
+	buf *dstruct.Stack[posRune]
 	src *bufio.Reader
+	pos *Position
 }
 
 func NewReader(r io.Reader) *Reader {
 	return &Reader{
-		buf: new(dstruct.Stack[rune]),
+		buf: new(dstruct.Stack[posRune]),
 		src: bufio.NewReader(r),
+		pos: &Position{},
 	}
 }
 
+func (r *Reader) psrn(rn rune) posRune {
+	return posRune{
+		Rune: rn,
+		Pos:  *r.pos,
+	}
+}
+
+func (r *Reader) Pos() (index, line, column int) {
+	return r.pos.Index, r.pos.Line, r.pos.Column
+}
+
 // Rune returns the next rune in r
 func (r *Reader) Rune() (rune, error) {
 	rn, _, err := r.src.ReadRune()
 	if err == nil {
-		r.buf.Push(rn)
+		r.buf.Push(r.psrn(rn))
+		r.pos.Advance(rn)
 	}
 	return rn, err
 }
@@ -38,9 +52,12 @@ func (r *Reader) UnreadRune() error {
 	}
 
 	if err := r.src.UnreadRune(); err == nil {
-		r.buf.Pop()
+		rn := r.buf.Pop()
+		*r.pos = rn.Pos
 	} else {
-		r.src = prependRune(r.buf.Pop(), r.src)
+		rn := r.buf.Pop()
+		*r.pos = rn.Pos
+		r.src = prependRune(rn.Rune, r.src)
 	}
 
 	return nil