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distinctopt.go
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distinctopt.go
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// Copyright (C) MongoDB, Inc. 2017-present.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
package distinctopt
import (
"reflect"
"time"
"github.com/mongodb/mongo-go-driver/core/option"
"github.com/mongodb/mongo-go-driver/core/session"
"github.com/mongodb/mongo-go-driver/mongo/mongoopt"
)
var distinctBundle = new(DistinctBundle)
// Distinct represents all passable params for the distinct() function.
type Distinct interface {
distinct()
}
// DistinctOption represents the options for the distinct() function.
type DistinctOption interface {
Distinct
ConvertDistinctOption() option.DistinctOptioner
}
// DistinctSession is the session for the distinct() function
type DistinctSession interface {
Distinct
ConvertDistinctSession() *session.Client
}
// DistinctBundle is a bundle of Distinct options.
type DistinctBundle struct {
option Distinct
next *DistinctBundle
}
func (db *DistinctBundle) distinct() {}
// ConvertDistinctOption implements the Distinct interface
func (db *DistinctBundle) ConvertDistinctOption() option.DistinctOptioner { return nil }
// BundleDistinct bundles Distinct options.
func BundleDistinct(opts ...Distinct) *DistinctBundle {
head := distinctBundle
for _, opt := range opts {
newBundle := DistinctBundle{
option: opt,
next: head,
}
head = &newBundle
}
return head
}
// Collation adds an option to specify a collation.
func (db *DistinctBundle) Collation(collation *mongoopt.Collation) *DistinctBundle {
bundle := &DistinctBundle{
option: Collation(collation),
next: db,
}
return bundle
}
// MaxTime adds an option to specify the maximum amount of time to allow the query to run.
func (db *DistinctBundle) MaxTime(d time.Duration) *DistinctBundle {
bundle := &DistinctBundle{
option: MaxTime(d),
next: db,
}
return bundle
}
// Unbundle transofrms a bundle into a slice of DistinctOptioner, optionally deduplicating.
func (db *DistinctBundle) Unbundle(deduplicate bool) ([]option.DistinctOptioner, *session.Client, error) {
options, sess, err := db.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 (db *DistinctBundle) bundleLength() int {
if db == nil {
return 0
}
bundleLen := 0
for ; db != nil; db = db.next {
if db.option == nil {
continue
}
if converted, ok := db.option.(*DistinctBundle); ok {
// nested bundle
bundleLen += converted.bundleLength()
continue
}
if _, ok := db.option.(DistinctSessionOpt); !ok {
bundleLen++
}
}
return bundleLen
}
// Helper that recursively unwraps bundle into slice of options
func (db *DistinctBundle) unbundle() ([]option.DistinctOptioner, *session.Client, error) {
if db == nil {
return nil, nil, nil
}
var sess *session.Client
listLen := db.bundleLength()
options := make([]option.DistinctOptioner, listLen)
index := listLen - 1
for listHead := db; 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.(*DistinctBundle); 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 DistinctOption:
options[index] = t.ConvertDistinctOption()
index--
case DistinctSession:
if sess == nil {
sess = t.ConvertDistinctSession()
}
}
}
return options, sess, nil
}
// String implements the Stringer interface
func (db *DistinctBundle) String() string {
if db == nil {
return ""
}
str := ""
for head := db; head != nil && head.option != nil; head = head.next {
if converted, ok := head.option.(*DistinctBundle); ok {
str += converted.String()
continue
}
if conv, ok := head.option.(DistinctOption); !ok {
str += conv.ConvertDistinctOption().String() + "\n"
}
}
return str
}
// Collation specifies a collation.
func Collation(collation *mongoopt.Collation) OptCollation {
return OptCollation{
Collation: collation.Convert(),
}
}
// MaxTime adds an optin to specify the maximum amount of time to allow the query to run.
func MaxTime(d time.Duration) OptMaxTime {
return OptMaxTime(d)
}
// OptCollation specifies a collation
type OptCollation option.OptCollation
func (OptCollation) distinct() {}
// ConvertDistinctOption implements the Distinct interface.
func (opt OptCollation) ConvertDistinctOption() option.DistinctOptioner {
return option.OptCollation(opt)
}
// OptMaxTime specifies the maximum amount of time to allow the query to run.
type OptMaxTime option.OptMaxTime
func (OptMaxTime) distinct() {}
// ConvertDistinctOption implements the Distinct interface.
func (opt OptMaxTime) ConvertDistinctOption() option.DistinctOptioner {
return option.OptMaxTime(opt)
}
// DistinctSessionOpt is an distinct session option.
type DistinctSessionOpt struct{}
func (DistinctSessionOpt) distinct() {}
// ConvertDistinctSession implements the DistinctSession interface.
func (DistinctSessionOpt) ConvertDistinctSession() *session.Client {
return nil
}