xast provides Walk()/WalkNode() functions, similar to astrewrite.Walk from the
astrewrite package. The main difference is that the passed walk function can also
check a node's parent.
Also deleting a node will automatically remove any assocociated comments with it.
Note that this is similar to https://go-review.googlesource.com/c/go/+/55790 but the API itself is a lot simpler.
package main
import (
"bytes"
"fmt"
"go/ast"
"go/parser"
"go/printer"
"go/token"
"github.com/OneOfOne/xast"
)
func main() {
src := `package main
// Foo is a foo!
type Foo struct{}
// NotFoo is not a foo!
type NotFoo struct{}
`
fset := token.NewFileSet()
file, err := parser.ParseFile(fset, "foo.go", src, parser.ParseComments)
if err != nil {
panic(err)
}
rewriteFn := func(n *xast.Node) *xast.Node {
switch x := n.Node().(type) {
case *ast.TypeSpec:
if x.Name.Name == "Foo" {
x.Name.Name = "Bar"
}
case *ast.CommentGroup:
// check n.Text()?
x.List = nil
return n.Break() // don't delete the node but don't go down it's children list.
// or if you want to remove a single comment out of a group
case *ast.Comment: // won't ever get here since we return n.Break() from case *ast.CommentGroup.
panic("can't get here now")
return n.Nil() // delete this node
}
return n
}
var buf bytes.Buffer
printer.Fprint(&buf, fset, xast.Walk(file, rewriteFn))
fmt.Println(buf.String())
}