I am not sure what "import external packages" means.
Apart dot imports (which I have never seen used for real) why would you
need to load the imported packages?
On Saturday, 16 October 2021 at 20:34:17 UTC+1 Steven Hartland wrote:
> Thanks Richard, that allowed me to replace a hand rolled universe scope 👍
>
> My importer varies from yours in that for correct lookups for versioned
> packages or those with '-' in I had to copy ImportPathToAssumedName from
> x/tools/internal/imports/fix.go.
>
> func simpleImporter(imports map[string]*ast.Object, path string)
> (*ast.Object, error) {
> pkg := imports[path]
> if pkg == nil {
> pkg = ast.NewObj(ast.Pkg, ImportPathToAssumedName(path))
> pkg.Data = ast.NewScope(nil) // required by ast.NewPackage
> for dot-import
> imports[path] = pkg
> }
> return pkg, nil
> }
>
> This now works for all cases which don't import external packages. So now
> I just need to do the on demand load of packages, which I suspect will lead
> me right back to packages.Load.
>
> On Sat, 16 Oct 2021 at 15:59, 'Richard Oudkerk' via golang-nuts <
> golan...@googlegroups.com> wrote:
>
>> You could try building the universe scope for ast.NewPackage from
>> types.Universe. For example
>>
>> https://play.golang.org/p/1E5Iu4vW3g9
>>
>> func NewPackage(fset *token.FileSet, files map[string]*ast.File)
>> (*ast.Package, error) {
>> univ, err := universe()
>> if err != nil {
>> return nil, err
>> }
>> return ast.NewPackage(fset, files, dummyImporter, univ)
>> }
>>
>> func dummyImporter(imports map[string]*ast.Object, importPath string)
>> (*ast.Object, error) {
>> pkg := imports[importPath]
>> if pkg == nil {
>> pkg = ast.NewObj(ast.Pkg, path.Base(importPath))
>> pkg.Data = ast.NewScope(nil)
>> imports[importPath] = pkg
>> }
>> return pkg, nil
>> }
>>
>> func universe() (*ast.Scope, error) {
>> u := ast.NewScope(nil)
>> for _, name := range types.Universe.Names() {
>> o := types.Universe.Lookup(name)
>> if o == nil {
>> return nil, fmt.Errorf("failed to lookup %s in universe scope", name)
>> }
>> var objKind ast.ObjKind
>> switch o.(type) {
>> case *types.Const, *types.Nil:
>> objKind = ast.Con
>> case *types.TypeName:
>> objKind = ast.Typ
>> case *types.Builtin:
>> objKind = ast.Fun
>> default:
>> return nil, fmt.Errorf("unexpected builtin %s of type %T", o.Name(), o)
>> }
>> obj := ast.NewObj(objKind, name)
>> if u.Insert(obj) != nil {
>> return nil, fmt.Errorf("types internal error: double declaration")
>> }
>> obj.Decl = u
>> }
>> return u, nil
>> }
>>
>> On Saturday, 16 October 2021 at 14:38:43 UTC+1 eli...@gmail.com wrote:
>>
>>> On Fri, Oct 15, 2021 at 2:13 PM Steven Hartland <ste...@multiplay.co.uk>
>>> wrote:
>>>
>>>> I converted my code to x/tools/go/packages
>>>> <https://pkg.go.dev/golang.org/x/tools@v0.1.7/go/packages> and while
>>>> it did solve the problem it's VERY slow in comparison.
>>>>
>>>> I have a set of 21 tests operating on a single package which has at
>>>> most two very basic types, no imports and using go/parser
>>>> <https://pkg.go.dev/go/parser> they take 0.011s but with go/packages
>>>> <https://pkg.go.dev/golang.org/x/tools@v0.1.7/go/packages> that
>>>> increases to 3.548s a 300x slow down.
>>>>
>>>> I'm setting a basic mode: packages.NeedName | packages.NeedSyntax
>>>>
>>>> The package.Load call takes ~220ms whereas ast.NewPackage only
>>>> takes 2.7µs.
>>>>
>>>
>>> Could you post a reproducer of your target package and analysis
>>> somewhere? 220ms for packages.Load sounds like a lot. It's true that
>>> packages does a lot more work than just the parser (*), but it's not
>>> supposed to be that slow. In my tests a simple Load with more functionality
>>> takes 60-70ms
>>>
>>> (*) The type checking takes a bit of time over just parsing to AST, but
>>> the biggest difference is loading multiple files from imports. For type
>>> checking you need to know, when you see:
>>>
>>> import foo
>>>
>>> x := foo.Foo()
>>>
>>> What the type of `x` is, so go/packages has to analyze the `foo` package
>>> as well.
>>>
>>>
>>>
>>>>
>>>> As the resulting ast.File's are pretty much the same, I'm wondering if
>>>> for my use case packages.Load is doing way more than I need?
>>>>
>>>> Another downside is for tests run in a temporary directory outside of
>>>> the package space package.Load fails with:
>>>> directory /tmp/tests76985775 outside available modules
>>>>
>>>> I fixed it by calling ioutil.TempDir with "." but that's not ideal.
>>>>
>>>> Thoughts?
>>>>
>>>> On Tue, 12 Oct 2021 at 13:42, Steven Hartland <ste...@multiplay.co.uk>
>>>> wrote:
>>>>
>>>>> Thanks David, much appreciated, I will have a look at both.
>>>>>
>>>>> When migrating from go/ast to go/types did you hit anything of note I
>>>>> should look out for?
>>>>>
>>>>> On Mon, 11 Oct 2021 at 17:06, David Finkel <david....@gmail.com>
>>>>> wrote:
>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, Oct 11, 2021 at 5:48 AM Steven Hartland <
>>>>>> ste...@multiplay.co.uk> wrote:
>>>>>>
>>>>>>> If the ast.Files passed to ast.NewPackage includes built in types
>>>>>>> such as int it returns an error e.g.
>>>>>>> file1.go:5:6: undeclared name: int
>>>>>>>
>>>>>>> Is there a way to prevent that?
>>>>>>>
>>>>>>
>>>>>> Generally, I always add the `builtin` package to the list of packages
>>>>>> I'm parsing.
>>>>>> I wrote a little library for exactly this kind of package loading a
>>>>>> few years ago:
>>>>>> https://gitlab.com/dfinkel/goastpkg/-/blob/master/go_ast_parser.go
>>>>>> (https://pkg.go.dev/golang.spin-2.net/astpkg)
>>>>>>
>>>>>>>
>>>>>>> Playground example: https://play.golang.org/p/Yg30TTzoLHP
>>>>>>>
>>>>>>> My goal is to take multiple files, resolve inter file dependencies
>>>>>>> e.g. a type referencing another type in a different file and process
>>>>>>> the
>>>>>>> resulting ast.Files. So if there is a better way to achieve this I'm
>>>>>>> all
>>>>>>> ears.
>>>>>>>
>>>>>>
>>>>>> In general, I've stopped using the `go/ast` internal references as
>>>>>> much and have started using resolved `go/types` references as they're
>>>>>> more
>>>>>> reliable and better-specified.
>>>>>> (golang.org/x/tools/go/packages
>>>>>> <https://pkg.go.dev/golang.org/x/tools@v0.1.7/go/packages> has a
>>>>>> LoadMode flag for generating `go/types.Info` (NeedTypesInfo
>>>>>> <https://pkg.go.dev/golang.org/x/tools@v0.1.7/go/packages#NeedTypesInfo>
>>>>>> ))
>>>>>>
>>>>>>>
>>>>>>> Regards
>>>>>>> Steve
>>>>>>>
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>>>>>>>
>>>>>>> <https://groups.google.com/d/msgid/golang-nuts/CAHEMsqbJoJxuo3c-mofMtzXXJhYCzV2skW2ZB3ZPY6WtA8%2BxHw%40mail.gmail.com?utm_medium=email&utm_source=footer>
>>>>>>> .
>>>>>>>
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