route/vendor/github.com/asdine/storm/internal/boltdb.go

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2017-04-28 23:28:25 +00:00
package internal
import "github.com/boltdb/bolt"
// Cursor that can be reversed
type Cursor struct {
C *bolt.Cursor
Reverse bool
}
// First element
func (c *Cursor) First() ([]byte, []byte) {
if c.Reverse {
return c.C.Last()
}
return c.C.First()
}
// Next element
func (c *Cursor) Next() ([]byte, []byte) {
if c.Reverse {
return c.C.Prev()
}
return c.C.Next()
}
// RangeCursor that can be reversed
type RangeCursor struct {
C *bolt.Cursor
Reverse bool
Min []byte
Max []byte
CompareFn func([]byte, []byte) int
}
// First element
func (c *RangeCursor) First() ([]byte, []byte) {
if c.Reverse {
return c.C.Seek(c.Max)
}
return c.C.Seek(c.Min)
}
// Next element
func (c *RangeCursor) Next() ([]byte, []byte) {
if c.Reverse {
return c.C.Prev()
}
return c.C.Next()
}
// Continue tells if the loop needs to continue
func (c *RangeCursor) Continue(val []byte) bool {
if c.Reverse {
return val != nil && c.CompareFn(val, c.Min) >= 0
}
return val != nil && c.CompareFn(val, c.Max) <= 0
}