feat(cassandra): add CQL parser with full Cassandra 4.1 grammar support

cassandra/ast/walk.go

@@ -0,0 +1,35 @@
+package ast
+
+// Visitor defines the interface for AST traversal.
+type Visitor interface {
+	Visit(node Node) Visitor
+}
+
+// Walk traverses an AST in depth-first order. It calls v.Visit(node); if that
+// returns a non-nil Visitor w, Walk recurses into the children of node with w,
+// then calls w.Visit(nil).
+func Walk(v Visitor, node Node) {
+	if node == nil {
+		return
+	}
+	if v = v.Visit(node); v == nil {
+		return
+	}
+	walkChildren(v, node)
+	v.Visit(nil)
+}
+
+// Inspect traverses an AST in depth-first order, calling f for each node.
+// If f returns true, Inspect recurses into the children of node.
+func Inspect(node Node, f func(Node) bool) {
+	Walk(inspector(f), node)
+}
+
+type inspector func(Node) bool
+
+func (f inspector) Visit(node Node) Visitor {
+	if node == nil || !f(node) {
+		return nil
+	}
+	return f
+}