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package sophia
import (
"errors"
"unsafe"
)
// Order string type of sophia cursor order
type Order string
// Constants for sophia cursor order
// They are used while creating cursor to select it's direction
const (
GreaterThan Order = ">"
GT Order = GreaterThan
GreaterThanEqual Order = ">="
GTE Order = GreaterThanEqual
LessThan Order = "<"
LT Order = LessThan
LessThanEqual Order = "<="
LTE Order = LessThanEqual
)
const (
// CursorPrefix uses for setting cursor prefix
CursorPrefix = "prefix"
// CursorOrder uses for setting cursor order
CursorOrder = "order"
)
// ErrCursorClosed will be returned in case of closed cursor usage
var ErrCursorClosed = errors.New("usage of closed Cursor")
// Cursor iterates over key-values in a database.
type Cursor struct {
ptr unsafe.Pointer
doc *Document
closed bool
}
// Close closes the cursor. If a cursor is not closed, future operations
// on the database can hang indefinitely.
// Cursor won't be accessible after this
func (cur *Cursor) Close() error {
if cur.closed {
return ErrCursorClosed
}
cur.doc.Free()
cur.closed = true
if !spDestroy(cur.ptr) {
return errors.New("cursor: failed to close")
}
return nil
}
// Next fetches the next row for the cursor
// Returns next row if it exists else it will return nil
func (cur *Cursor) Next() *Document {
if cur.closed {
return nil
}
ptr := spGet(cur.ptr, cur.doc.ptr)
if ptr == nil {
return nil
}
cur.doc.ptr = ptr
return cur.doc
}
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