[refactoring] remove scanner token

pkg/position/pool.go

@@ -0,0 +1,29 @@
+package position
+
+const DefaultBlockSize = 1024
+
+type Pool struct {
+	block []Position
+	off   int
+}
+
+func NewPool(blockSize int) *Pool {
+	return &Pool{
+		block: make([]Position, blockSize),
+	}
+}
+
+func (p *Pool) Get() *Position {
+	if len(p.block) == 0 {
+		return nil
+	}
+
+	if len(p.block) == p.off {
+		p.block = make([]Position, len(p.block))
+		p.off = 0
+	}
+
+	p.off++
+
+	return &p.block[p.off-1]
+}