Thanks for looking at it :smile: Could you elaborate more on how the `SetLines` would work on a `token.FileSet`? I thought that `SetLines` is only for the `os.File` types :sweat: Do you mean that I should create offsets (using SetLines) before I create the FileSet out of it?
reference code: https://github.com/tjgurwara99/constr/blob/0e0f8952c652b7a7a10b7238daed90132b924084/construct.go#L31 On Tuesday, 25 October 2022 at 01:07:23 UTC+1 david....@gmail.com wrote: > On Sat, Oct 22, 2022 at 10:00 PM Tajmeet Singh <tjgur...@gmail.com> wrote: > >> Hello, >> >> I've been working on a utility to generate constructors for me when I >> provide it with a path to the file containing the struct and it `Ident`. >> The idea was that I would just create a ast.Node (FuncDecl) with all the >> necessary fields but I'm not able to figure out the positioning of the >> commas. >> >> The function that I'm working on looks something like this: >> >> ```Go >> func generateConstructor(typeName string, fields ...*ast.Field) >> *ast.FuncDecl { >> var elts []ast.Expr >> >> for _, field := range fields { >> elts = append(elts, &ast.KeyValueExpr{ >> Key: field.Names[0], >> Value: field.Names[0], >> }) >> } >> return &ast.FuncDecl{ >> Doc: nil, >> Recv: nil, >> Name: ast.NewIdent("New" + typeName), >> Type: &ast.FuncType{ >> TypeParams: nil, >> Params: &ast.FieldList{ >> List: fields, >> }, >> Results: nil, >> }, >> Body: &ast.BlockStmt{ >> Lbrace: 1, >> List: []ast.Stmt{ >> &ast.ReturnStmt{ >> Results: []ast.Expr{ >> &ast.UnaryExpr{ >> Op: token.AND, >> X: &ast.CompositeLit{ >> Type: ast.NewIdent(typeName), >> Elts: elts, >> Rbrace: 1, >> }, >> }, >> }, >> }, >> }, >> Rbrace: 2, >> }, >> } >> } >> ``` >> >> And when I provide it with a struct like this: >> >> ```Go >> type Data struct { >> something string >> data string >> dd int >> } >> ``` >> I get this when I do `format.Node` on the generated node `functionDecl`. >> >> ```Go >> func NewData(something string, >> data string, >> dd int) { >> return &Data{something: something, >> data: data, >> dd: dd} >> } >> ``` >> >> However, I was thinking that it would look something like this. >> >> ```Go >> func NewData(something string, >> data string, >> dd int, >> ) { >> return &Data{something: something, >> data: data, >> dd: dd, >> } >> } >> ``` >> (wishful thinking :joy:) >> >> Anyways, I tried to figure out how the `token.COMMA` is used in the >> parser and how the ast is affected but I couldn't figure it out. Maybe it >> is related to the `Lbrace` and `Rbrace` values which I'm deliberately >> missing. Any help would be much appreciated :smile: :pray: >> > > Looking at the code, I think you're on the right track with Rbrace's > location being the determining factor when to insert a comma and move put > the closing brace on a new line. > My recommendation would be to use `SetLines` > <https://pkg.go.dev/go/token@go1.19.2#File.SetLines> on the (hopefully > clean) `token.FileSet` you're passing to `format.Node` to declare some > new-line offsets. I don't think the offsets have to make sense as they > would in a file that was parsed, but the formatter needs to see the last > expression and close brace as being on different lines > > The type-switch line that handles CompositeLit's call handling insertions: > https://cs.opensource.google/go/go/+/refs/tags/go1.19.2:src/go/printer/nodes.go;l=1021;drc=7e72d384d66f48a78289edc6a7d1dc6ab878f990 > The lines that handle making the decision about inserting a new line: > https://cs.opensource.google/go/go/+/refs/tags/go1.19.2:src/go/printer/nodes.go;l=297-299;drc=a1901f898bc05aac966edd247ff122f52fbb8d2e > >> >> PS: I'm not aware of any utility out there so have to roll my own :joy: >> and learn whilst at it; if people are aware of it, please let me know and >> I'll inspect their code and figure things out :smile: >> >> -- >> You received this message because you are subscribed to the Google Groups >> "golang-nuts" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to golang-nuts...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/ffa312d0-5652-4c2d-9c71-c74bc4bfc56bn%40googlegroups.com >> >> <https://groups.google.com/d/msgid/golang-nuts/ffa312d0-5652-4c2d-9c71-c74bc4bfc56bn%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/ca7fa4ed-247c-42fa-baa3-81a905ae1ecdn%40googlegroups.com.
