Support 1.23 iterator

[amikai]

Hi @itchyny,

The goquery package itself has already implemented the Iter interface. Have you considered supporting the 1.23 iterator, allowing users to directly use for-range on it?

goquery has already implemented its own Iter. Directly switching to iter.Seq or iter.Seq2 in version 1.23 is not practical. Therefore, my idea is to implement an adapter to convert it to iter.Seq or iter.Seq2.

Here is my rough idea.

package gojq

func ToSeq2(it Iter) iter.Seq2[any, error] {
	return func(yield func(x any, err error) bool) {
		for {
			v, ok := it.Next()
			if !ok {
				break
			}
			if err, ok := v.(error); ok {
				if !yield(nil, err) {
					break
				}
			} else {
				if !yield(v, nil) {
					break
				}
			}
		}
	}
}

The client will use it like this. Here is the code from the readme example, modified to use ToSeq2:

query, err := gojq.Parse(".foo | ..")
if err != nil {
	log.Fatalln(err)
}
input := map[string]any{"foo": []any{1, 2, 3}}
for val, err := range gojq.ToSeq2(query.Run(input)) {
	if err != nil {
		if err, ok := err.(*gojq.HaltError); ok && err.Value() == nil {
			break
		}
		log.Fatalln(err)
	}
	fmt.Printf("%#v\n", val)
}

[itchyny]

Yes, this is on my todo list and I have a patch locally. I will gradually update the Go version carefully, while watching the reactions to the new features. Please wait.

[amikai]

Hi @itchyny, we can use the following function signature to avoid upgrading the go.mod version:

func ToSeq2(it Iter) func(yield func(K, V) bool)

For users on Go 1.23 or later, they can use for-range to iterate over it while keeping the original go.mod version, ensuring backward compatibility with the original API.

NOTE: If you think our discussion and ideas are mature enough, feel free to ask me to open a PR.

[itchyny]

I'm thinking of adding RunSeq and RunSeqWithContext returning iter.Seq2[any, error]. Thoughts?