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Ensure a cursor can continue to iterate elements in reverse direction by call Next when it has already reached the beginning
Signed-off-by: Benjamin Wang <benjamin.ahrtr@gmail.com>
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parent
e457711987
commit
6967960a72
11
cursor.go
11
cursor.go
@ -74,7 +74,7 @@ func (c *Cursor) Last() (key []byte, value []byte) {
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// If this is an empty page (calling Delete may result in empty pages)
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// we call prev to find the last page that is not empty
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for len(c.stack) > 0 && c.stack[len(c.stack)-1].count() == 0 {
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for len(c.stack) > 1 && c.stack[len(c.stack)-1].count() == 0 {
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c.prev()
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}
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@ -257,6 +257,15 @@ func (c *Cursor) prev() (key []byte, value []byte, flags uint32) {
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elem.index--
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break
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}
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// If we've hit the beginning, we should stop moving the cursor,
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// and stay at the first element, so that users can continue to
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// iterate over the elements in reverse direction by calling `Next`.
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// We should return nil in such case.
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// Refer to https://github.com/etcd-io/bbolt/issues/733
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if len(c.stack) == 1 {
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c.first()
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return nil, nil, 0
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}
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c.stack = c.stack[:i]
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}
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