go-toolsmith / astcopy Goto Github PK

The problem: astcopy functions do not copy ast.Object fields because some projects may not care about them at all (go/types.Object is better and deprecates ast.Object). But if for whatever reason user must copy objects, there will be troubles.

I'm proposing this functions:

func IdentObjects(dst, src *ast.Ident) {/**/}
func ScopeObjects(dst, src *ast.Scope) {/**/}
func PackageObjects(dst, src *ast.Package) {/**/}

So, copy of *ast.Ident with objects may be done this way:

y := astcopy.Ident(x)
astcopy.IdentObjects(y, x)

This can be wrapped by user into simple function:

func copyIdent(x) *ast.Ident {
  y := astcopy.Ident(x)
  astcopy.IdentObjects(y, x)
  return y
}

This way, we avoid quite expensive copy that may be unnecessary in a first place and provide a way to copy objects if they are required.

Note that copying objects may be non-trivial.
It needs some investigation and problem overview beforehand.

I've come across a problem where I want to copy everything except the position.
To solve this problem I cloned astcopy.go and made changes to all functions.

For example, this is how the UnaryExpr is now copied:

func UnaryExpr(x *ast.UnaryExpr) *ast.UnaryExpr {
	if x == nil {
		return nil
	}
	return &ast.UnaryExpr{
		Op: x.Op,
		X:  copyExpr(x.X),
	}
}

Is this something you would like to incorporate into this repo. Otherwise I will clone this repo and make an alternative version of it.