fixed column indexing

position.go

@@ -10,7 +10,7 @@ func (p *Position) Advance(rn rune) {
 	p.Index++
 	if rn == '\n' {
 		p.Line++
-		p.Column = 0
+		p.Column = 1
 	} else {
 		p.Column++
 	}

reader.go

@@ -14,14 +14,18 @@ type Reader struct {
 	pos *Position
 }
 
-func NewReader(r io.Reader) *Reader {
+func New(r io.Reader) *Reader {
 	return &Reader{
 		buf: ds.NewArrayStack[posRune](),
 		src: bufio.NewReader(r),
-		pos: &Position{},
+		pos: &Position{Index: 0, Line: 1, Column: 1},
 	}
 }
 
+func NewFromString(str string) *Reader {
+	return New(strings.NewReader(str))
+}
+
 func (r *Reader) psrn(rn rune) posRune {
 	return posRune{
 		Rune: rn,
@@ -149,12 +153,6 @@ func (r *Reader) PeekStringWhile(f ...RuneFunc) (string, error) {
 	return str, nil
 }
 
-// SkipStringWhile acts as StringWhile but discards the string
-func (r *Reader) SkipStringWhile(f ...RuneFunc) error {
-	_, err := r.StringWhile(f...)
-	return err
-}
-
 // StringUntil reads runes and calls all functions for each one.
 // It returns all runes as a string for which all functions returned true.
 // It stops when any function returns false or an error occured.
@@ -177,10 +175,33 @@ func (r *Reader) PeekStringUntil(f ...RuneFunc) (string, error) {
 	return str, nil
 }
 
-// SkipStringUntil acts as StringUntil but discards the string
+// SkipUntil acts as StringUntil but discards the string
-func (r *Reader) SkipStringUntil(f ...RuneFunc) error {
+// The rune for which that function returned false will be unread.
+func (r *Reader) SkipUntil(f ...RuneFunc) error {
 	_, err := r.StringUntil(f...)
-	return err
+	if err != nil {
+		return err
+	}
+	return r.UnreadRune()
+}
+
+// SkipWhile acts as StringWhile but discards the string.
+// The rune for which that function returned false will be unread.
+func (r *Reader) SkipWhile(f ...RuneFunc) error {
+	_, err := r.StringWhile(f...)
+	if err != nil {
+		return err
+	}
+	return r.UnreadRune()
+}
+
+// ExpectRune returns true if any function returns true for the next rune read from r
+func (r *Reader) ExpectRune(f ...RuneFunc) (bool, error) {
+	rn, err := r.Rune()
+	if err != nil {
+		return false, err
+	}
+	return findFirstTrue(rn, f), nil
 }
 
 // Commit clears the internal buffer and therefore removes all data which were already read.

reader_test.go

@@ -7,7 +7,7 @@ import (
 )
 
 func TestPos(t *testing.T) {
-	r := NewReader(strings.NewReader("hello world\nsecond line"))
+	r := New(strings.NewReader("hello world\nsecond line"))
 
 	unread := false
 	for rn, err := r.Rune(); err == nil; rn, err = r.Rune() {
@@ -24,7 +24,7 @@ func TestPos(t *testing.T) {
 }
 
 func TestEOF(t *testing.T) {
-	r := NewReader(strings.NewReader("hello world\nasddsa"))
+	r := New(strings.NewReader("hello world\nasddsa"))
 
 	var line string
 	var err error