Function paginateList

mcp/server.go:1575–1611

paginateList is a generic helper that returns a paginated slice of items from a featureSet. It populates the provided result res with the items and sets its next cursor for subsequent pages. If there are no more pages, the next cursor within the result will be an empty string.

(fs *featureSet[T], pageSize int, params P, res R, setFunc func(R, []T))

// and sets its next cursor for subsequent pages.
// If there are no more pages, the next cursor within the result will be an empty string.
func paginateList[P listParams, R listResult[T], T any](fs *featureSet[T], pageSize int, params P, res R, setFunc func(R, []T)) (R, error) {
	var seq iter.Seq[T]
	if params.cursorPtr() == nil || *params.cursorPtr() == "" {
		seq = fs.all()
	} else {
		pageToken, err := decodeCursor(*params.cursorPtr())
		// According to the spec, invalid cursors should return Invalid params.
		if err != nil {
			var zero R
			return zero, jsonrpc2.ErrInvalidParams
		}
		seq = fs.above(pageToken.LastUID)
	}
	var count int
	var features []T
	for f := range seq {
		count++
		// If we've seen pageSize + 1 elements, we've gathered enough info to determine
		// if there's a next page. Stop processing the sequence.
		if count == pageSize+1 {
			break
		}
		features = append(features, f)
	}
	setFunc(res, features)
	// No remaining pages.
	if count < pageSize+1 {
		return res, nil
	}
	nextCursor, err := encodeCursor(fs.uniqueID(features[len(features)-1]))
	if err != nil {
		var zero R
		return zero, err
	}
	*res.nextCursorPtr() = nextCursor
	return res, nil
}