Adding cdp.Node.WriteTo method

gen/gogen.go

@@ -186,8 +186,17 @@ func (fb fileBuffers) get(s string, pkgName string, d *pdl.Domain, domains []*pd
 		"github.com/mailru/easyjson/jwriter": "",
 		"github.com/chromedp/sysutil":        "",
 	}
+	// add io only for cdp package
+	if pkgName == "cdp" {
+		importMap["io"] = ""
+	}
 	for _, d := range domains {
-		importMap[basePkg+"/"+genutil.PackageName(d)] = ""
+		pn := genutil.PackageName(d)
+		// skip adding cdproto/io package to cdp package
+		if pkgName == "cdp" && pn == "io" {
+			continue
+		}
+		importMap[basePkg+"/"+pn] = ""
 	}
 	gotpl.StreamFileImportTemplate(w, importMap)
 

gen/gotpl/extra.qtpl

@@ -182,64 +182,121 @@ func (n *Node) FullXPath() string {
 	return n.xpath(false, false)
 }
 
-// Dump builds a printable string representation of the node and its children.
-func (n *Node) Dump(prefix, indent string, nodeIDs bool) string {
+// WriteTo writes a readable representation of the node and all its children to w.
+func (n *Node) WriteTo(w io.Writer, prefix, indent string, nodeIDs bool) (int, error) {
 	if n == nil {
-		return prefix + "<nil>"
+		return w.Write([]byte(prefix + "<nil>"))
 	}
 
 	n.RLock()
 	defer n.RUnlock()
 
-	s := n.LocalName
-	if s == "" {
-		s = n.NodeName
+	var err error
+	var nn, c int
+
+	// prefix
+	if c, err = w.Write([]byte(prefix)); err != nil {
+		return nn + c, err
 	}
+	nn += c
 
+	// node name
+	if n.LocalName != "" {
+		if c, err = w.Write([]byte(n.LocalName)); err != nil {
+			return nn + c, err
+		}
+		nn += c
+	} else {
+		if c, err = w.Write([]byte(n.NodeName)); err != nil {
+			return nn + c, err
+		}
+		nn += c
+	}
+
+	// add #id
+	var hasID int
 	for i := 0; i < len(n.Attributes); i += 2 {
 		if strings.ToLower(n.Attributes[i]) == "id" {
-			s += "#" + n.Attributes[i+1]
+			if c, err = w.Write([]byte("#" + n.Attributes[i+1])); err != nil {
+				return nn + c, err
+			}
+			nn += c
+			hasID = 2
 			break
 		}
 	}
 
+	// node type
 	if n.NodeType != NodeTypeElement && n.NodeType != NodeTypeText {
-		s += fmt.Sprintf(" <%s>", n.NodeType)
+		if c, err = fmt.Fprintf(w, " <%s>", n.NodeType); err != nil {
+			return nn + c, err
+		}
+		nn += c
 	}
 
+	// node value
 	if n.NodeType == NodeTypeText {
 		v := n.NodeValue
 		if len(v) > 15 {
 			v = v[:15] + "..."
 		}
-		s += fmt.Sprintf(" %q", v)
+		if c, err = fmt.Fprintf(w, " %q", v); err != nil {
+			return nn + c, err
+		}
+		nn += c
 	}
 
-	if n.NodeType == NodeTypeElement && len(n.Attributes) > 0 {
-		attrs := ""
-		for i := 0; i < len(n.Attributes); i += 2 {
+	// attributes
+	if n.NodeType == NodeTypeElement && len(n.Attributes) > hasID {
+		if c, err = w.Write([]byte(" [")); err != nil {
+			return nn + c, err
+		}
+		nn += c
+		for i, space := 0, ""; i < len(n.Attributes); i += 2 {
 			if strings.ToLower(n.Attributes[i]) == "id" {
 				continue
 			}
-			if attrs != "" {
-				attrs += " "
+			if c, err = fmt.Fprintf(w, "%s%s=%q", space, n.Attributes[i], n.Attributes[i+1]); err != nil {
+				return nn + c, err
+			}
+			nn += c
+			if space == "" {
+				space = " "
 			}
-			attrs += fmt.Sprintf("%s=%q", n.Attributes[i], n.Attributes[i+1])
 		}
-		if attrs != "" {
-			s += " [" + attrs + "]"
+		if c, err = w.Write([]byte{']'}); err != nil {
+			return nn + c, err
 		}
+		nn += c
 	}
 
+	// node id
 	if nodeIDs {
-		s += fmt.Sprintf(" (%d)", n.NodeID)
+		if c, err = fmt.Fprintf(w, " (%d)", n.NodeID); err != nil {
+			return nn + c, err
+		}
+		nn += c
 	}
 
+	// children
 	for i := 0; i < len(n.Children); i++ {
-		s += "\n" + n.Children[i].Dump(prefix+indent, indent, nodeIDs)
+		if c, err = fmt.Fprintln(w); err != nil {
+			return nn + c, err
+		}
+		nn += c
+		if c, err = n.Children[i].WriteTo(w, prefix+indent, indent, nodeIDs); err != nil {
+			return nn + c, err
+		}
+		nn += c
 	}
+	return nn, nil
+}
 
-	return prefix + s
+// Dump builds a printable string representation of the node and its children.
+func (n *Node) Dump(prefix, indent string, nodeIDs bool) string {
+	var buf bytes.Buffer
+	_, _ = n.WriteTo(&buf, prefix, indent, nodeIDs)
+	return buf.String()
 }
 
 // NodeState is the state of a DOM node.