xast

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.

Example

package main
import (
"bytes""fmt""go/ast""go/parser""go/printer""go/token""github.com/OneOfOne/xast"
)
funcmain() {
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)
iferr!=nil {
panic(err)
}
rewriteFn:=func(n*xast.Node) *xast.Node {
switchx:=n.Node().(type) {
case*ast.TypeSpec:
ifx.Name.Name=="Foo" {
x.Name.Name="Bar"
}
case*ast.CommentGroup:
// check n.Text()?x.List=nilreturnn.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 groupcase*ast.Comment: // won't ever get here since we return n.Break() from case *ast.CommentGroup.panic("can't get here now")
returnn.Nil() // delete this node
}
returnn
}
varbuf bytes.Bufferprinter.Fprint(&buf, fset, xast.Walk(file, rewriteFn))
fmt.Println(buf.String())
}