route/vendor/github.com/asdine/storm/index/unique.go

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2017-04-28 23:28:25 +00:00
package index
import (
"bytes"
"github.com/asdine/storm/internal"
"github.com/boltdb/bolt"
)
// NewUniqueIndex loads a UniqueIndex
func NewUniqueIndex(parent *bolt.Bucket, indexName []byte) (*UniqueIndex, error) {
var err error
b := parent.Bucket(indexName)
if b == nil {
if !parent.Writable() {
return nil, ErrNotFound
}
b, err = parent.CreateBucket(indexName)
if err != nil {
return nil, err
}
}
return &UniqueIndex{
IndexBucket: b,
Parent: parent,
}, nil
}
// UniqueIndex is an index that references unique values and the corresponding ID.
type UniqueIndex struct {
Parent *bolt.Bucket
IndexBucket *bolt.Bucket
}
// Add a value to the unique index
func (idx *UniqueIndex) Add(value []byte, targetID []byte) error {
if value == nil || len(value) == 0 {
return ErrNilParam
}
if targetID == nil || len(targetID) == 0 {
return ErrNilParam
}
exists := idx.IndexBucket.Get(value)
if exists != nil {
if bytes.Equal(exists, targetID) {
return nil
}
return ErrAlreadyExists
}
return idx.IndexBucket.Put(value, targetID)
}
// Remove a value from the unique index
func (idx *UniqueIndex) Remove(value []byte) error {
return idx.IndexBucket.Delete(value)
}
// RemoveID removes an ID from the unique index
func (idx *UniqueIndex) RemoveID(id []byte) error {
c := idx.IndexBucket.Cursor()
for val, ident := c.First(); val != nil; val, ident = c.Next() {
if bytes.Equal(ident, id) {
return idx.Remove(val)
}
}
return nil
}
// Get the id corresponding to the given value
func (idx *UniqueIndex) Get(value []byte) []byte {
return idx.IndexBucket.Get(value)
}
// All returns all the ids corresponding to the given value
func (idx *UniqueIndex) All(value []byte, opts *Options) ([][]byte, error) {
id := idx.IndexBucket.Get(value)
if id != nil {
return [][]byte{id}, nil
}
return nil, nil
}
// AllRecords returns all the IDs of this index
func (idx *UniqueIndex) AllRecords(opts *Options) ([][]byte, error) {
var list [][]byte
c := internal.Cursor{C: idx.IndexBucket.Cursor(), Reverse: opts != nil && opts.Reverse}
for val, ident := c.First(); val != nil; val, ident = c.Next() {
if opts != nil && opts.Skip > 0 {
opts.Skip--
continue
}
if opts != nil && opts.Limit == 0 {
break
}
if opts != nil && opts.Limit > 0 {
opts.Limit--
}
list = append(list, ident)
}
return list, nil
}
// Range returns the ids corresponding to the given range of values
func (idx *UniqueIndex) Range(min []byte, max []byte, opts *Options) ([][]byte, error) {
var list [][]byte
c := internal.RangeCursor{
C: idx.IndexBucket.Cursor(),
Reverse: opts != nil && opts.Reverse,
Min: min,
Max: max,
CompareFn: func(val, limit []byte) int {
return bytes.Compare(val, limit)
},
}
for val, ident := c.First(); val != nil && c.Continue(val); val, ident = c.Next() {
if opts != nil && opts.Skip > 0 {
opts.Skip--
continue
}
if opts != nil && opts.Limit == 0 {
break
}
if opts != nil && opts.Limit > 0 {
opts.Limit--
}
list = append(list, ident)
}
return list, nil
}
// first returns the first ID of this index
func (idx *UniqueIndex) first() []byte {
c := idx.IndexBucket.Cursor()
for val, ident := c.First(); val != nil; val, ident = c.Next() {
return ident
}
return nil
}