Golang go/printer.CommentedNode type example

package go/printer

A CommentedNode bundles an AST node and corresponding comments. It may be provided as argument to any of the Fprint functions.

Golang go/printer.CommentedNode type usage example

 func (lp *linePrinter) printWithComments(n ast.Node) {
  nfirst := lp.fset.Position(n.Pos()).Line
  nlast := lp.fset.Position(n.End()).Line
  for _, g := range lp.fnode.Comments {
 cfirst := lp.fset.Position(g.Pos()).Line
 clast := lp.fset.Position(g.End()).Line
 if clast == nfirst-1 && lp.fset.Position(n.Pos()).Column == lp.fset.Position(g.Pos()).Column {
 for _, c := range g.List {
 lp.output.WriteString(c.Text)
 lp.output.WriteByte('\n')
 }
 }
 if cfirst >= nfirst && cfirst <= nlast && n.End() <= g.List[0].Slash {
 // The printer will not include the comment if it starts past
 // the node itself. Trick it into printing by overlapping the
 // slash with the end of the statement.
 g.List[0].Slash = n.End() - 1
 }
  }
  node := &printer.CommentedNode{n, lp.fnode.Comments} // <-- here
  lp.config.Fprint(&lp.output, lp.fset, node)
 }

References :

https://github.com/adjust/gocheck/blob/master/printer.go

http://golang.org/pkg/go/printer/#CommentedNode