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listdbopt.go
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listdbopt.go
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package listdbopt
import (
"reflect"
"github.com/mongodb/mongo-go-driver/core/option"
"github.com/mongodb/mongo-go-driver/core/session"
)
var listDatabasesBundle = new(ListDatabasesBundle)
// ListDatabases represents all possible params for the listDatabases() function.
type ListDatabases interface {
listDatabases()
}
// ListDatabasesOption represents the options for the listDatabases() function.
type ListDatabasesOption interface {
ListDatabases
ConvertListDatabasesOption() option.ListDatabasesOptioner
}
// ListDatabasesSession is the session for the ListDatabases() function.
type ListDatabasesSession interface {
ListDatabases
ConvertListDatabasesSession() *session.Client
}
// ListDatabasesBundle is a bundle of ListDatabases options
type ListDatabasesBundle struct {
option ListDatabases
next *ListDatabasesBundle
}
// Implement the ListDatabases interface
func (lcb *ListDatabasesBundle) listDatabases() {}
// ConvertListDatabasesOption implements the ListDatabases interface
func (lcb *ListDatabasesBundle) ConvertListDatabasesOption() option.ListDatabasesOptioner {
return nil
}
// BundleListDatabases bundles ListDatabases options
func BundleListDatabases(opts ...ListDatabases) *ListDatabasesBundle {
head := listDatabasesBundle
for _, opt := range opts {
newBundle := ListDatabasesBundle{
option: opt,
next: head,
}
head = &newBundle
}
return head
}
// NameOnly adds an option to specify whether to return only the collection names.
func (lcb *ListDatabasesBundle) NameOnly(b bool) *ListDatabasesBundle {
bundle := &ListDatabasesBundle{
option: NameOnly(b),
next: lcb,
}
return bundle
}
// Unbundle transforms a bundle into a slice of options, optionally deduplicating.
func (lcb *ListDatabasesBundle) Unbundle(deduplicate bool) ([]option.ListDatabasesOptioner, *session.Client, error) {
options, sess, err := lcb.unbundle()
if err != nil {
return nil, nil, err
}
if !deduplicate {
return options, sess, nil
}
// iterate backwards and make dedup slice
optionsSet := make(map[reflect.Type]struct{})
for i := len(options) - 1; i >= 0; i-- {
currOption := options[i]
optionType := reflect.TypeOf(currOption)
if _, ok := optionsSet[optionType]; ok {
// option already found
options = append(options[:i], options[i+1:]...)
continue
}
optionsSet[optionType] = struct{}{}
}
return options, sess, nil
}
// Calculates the total length of a bundle, accounting for nested bundles.
func (lcb *ListDatabasesBundle) bundleLength() int {
if lcb == nil {
return 0
}
bundleLen := 0
for ; lcb != nil; lcb = lcb.next {
if lcb.option == nil {
continue
}
if converted, ok := lcb.option.(*ListDatabasesBundle); ok {
// nested bundle
bundleLen += converted.bundleLength()
continue
}
if _, ok := lcb.option.(ListDatabasesSessionOpt); !ok {
bundleLen++
}
}
return bundleLen
}
// Helper that recursively unwraps bundle into slice of options
func (lcb *ListDatabasesBundle) unbundle() ([]option.ListDatabasesOptioner, *session.Client, error) {
if lcb == nil {
return nil, nil, nil
}
var sess *session.Client
listLen := lcb.bundleLength()
options := make([]option.ListDatabasesOptioner, listLen)
index := listLen - 1
for listHead := lcb; listHead != nil; listHead = listHead.next {
if listHead.option == nil {
continue
}
// if the current option is a nested bundle, Unbundle it and add its options to the current array
if converted, ok := listHead.option.(*ListDatabasesBundle); ok {
nestedOptions, s, err := converted.unbundle()
if err != nil {
return nil, nil, err
}
if s != nil && sess == nil {
sess = s
}
// where to start inserting nested options
startIndex := index - len(nestedOptions) + 1
// add nested options in order
for _, nestedOp := range nestedOptions {
options[startIndex] = nestedOp
startIndex++
}
index -= len(nestedOptions)
continue
}
switch t := listHead.option.(type) {
case ListDatabasesOption:
options[index] = t.ConvertListDatabasesOption()
index--
case ListDatabasesSession:
if sess == nil {
sess = t.ConvertListDatabasesSession()
}
}
}
return options, sess, nil
}
// String implements the Stringer interface
func (lcb *ListDatabasesBundle) String() string {
if lcb == nil {
return ""
}
str := ""
for head := lcb; head != nil && head.option != nil; head = head.next {
if converted, ok := head.option.(*ListDatabasesBundle); ok {
str += converted.String()
continue
}
if conv, ok := head.option.(ListDatabasesOption); !ok {
str += conv.ConvertListDatabasesOption().String() + "\n"
}
}
return str
}
// NameOnly specifies whether to return only the collection names.
func NameOnly(b bool) OptNameOnly {
return OptNameOnly(b)
}
// OptNameOnly specifies whether to return only the collection names.
type OptNameOnly option.OptNameOnly
func (OptNameOnly) listDatabases() {}
// ConvertListDatabasesOption implements the ListDatabases interface.
func (opt OptNameOnly) ConvertListDatabasesOption() option.ListDatabasesOptioner {
return option.OptNameOnly(opt)
}
// ListDatabasesSessionOpt is a listDatabases session option.
type ListDatabasesSessionOpt struct{}
func (ListDatabasesSessionOpt) listDatabases() {}
// ConvertListDatabasesSession implements the ListDatabasesSession interface.
func (ListDatabasesSessionOpt) ConvertListDatabasesSession() *session.Client {
return nil
}