Merge pull request 'lexer: introduce a Position (Line, Column) handler' (#8)

Reviewed-on: #8

lexer/lexer.go

@@ -1,17 +1,2 @@
 // Package lexer provides basic helpers to implement parsers
 package lexer
-
-// StateFn is a State Function of the parser
-type StateFn func() (StateFn, error)
-
-// Run runs a state machine until the state function either
-// returns nil or an error
-func Run(fn StateFn) error {
-	var err error
-
-	for fn != nil && err == nil {
-		fn, err = fn()
-	}
-
-	return err
-}

lexer/position.go

@@ -41,28 +41,26 @@ func (p *Position) Step() {
 	p.Column++
 }
 
-// Next returns a new Position one rune forward
-// on the line
-func (p Position) Next() Position {
+// StepN moves the column N places forward
+func (p *Position) StepN(n int) {
 	if p.Line == 0 {
 		p.Reset()
 	}
 
-	return Position{
-		Line:   p.Line,
-		Column: p.Column + 1,
+	switch {
+	case n > 0:
+		p.Column += n
+	default:
+		panic(fmt.Errorf("invalid %v increment", n))
 	}
 }
 
-// NextLine returns a new Position at the begining of the next
-// line.
-func (p Position) NextLine() Position {
+// StepLine moves position to the start of the next line
+func (p *Position) StepLine() {
 	if p.Line == 0 {
 		p.Reset()
 	}
 
-	return Position{
-		Line:   p.Line + 1,
-		Column: 1,
-	}
+	p.Line++
+	p.Column = 1
 }

lexer/reader.go

@@ -198,41 +198,6 @@ func (b *Reader) PeekRune() (rune, int, error) {
 	return r, l, err
 }
 
-// Accept consumes a rune from the source if it meets the condition.
-// it returns true if the condition was met and false if it wasn't.
-func (b *Reader) Accept(cond func(r rune) bool) bool {
-	r, _, err := b.ReadRune()
-	switch {
-	case err != nil:
-		return false
-	case cond(r):
-		return true
-	default:
-		_ = b.UnreadRune()
-		return false
-	}
-}
-
-// AcceptAll consumes runes from the source as long as they meet the
-// condition. it returns true if the condition was met for at least one rune,
-// and false if it wasn't.
-func (b *Reader) AcceptAll(cond func(r rune) bool) bool {
-	var accepted bool
-
-	for {
-		r, _, err := b.ReadRune()
-		switch {
-		case err != nil:
-			return accepted
-		case cond(r):
-			accepted = true
-		default:
-			_ = b.UnreadRune()
-			return accepted
-		}
-	}
-}
-
 // NewReader creates a new runes [Reader] using the given [io.Reader]
 func NewReader(r io.Reader) *Reader {
 	if r == nil {