clone

vendor/github.com/asdine/storm/v3/internal/boltdb.go

@@ -0,0 +1,121 @@
+package internal
+
+import (
+	"bytes"
+
+	bolt "go.etcd.io/bbolt"
+)
+
+// 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 {
+		k, v := c.C.Seek(c.Max)
+
+		// If Seek doesn't find a key it goes to the next.
+		// If so, we need to get the previous one to avoid
+		// including bigger values. #218
+		if !bytes.HasPrefix(k, c.Max) && k != nil {
+			k, v = c.C.Prev()
+		}
+
+		return k, v
+	}
+
+	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
+}
+
+// PrefixCursor that can be reversed
+type PrefixCursor struct {
+	C       *bolt.Cursor
+	Reverse bool
+	Prefix  []byte
+}
+
+// First element
+func (c *PrefixCursor) First() ([]byte, []byte) {
+	var k, v []byte
+
+	for k, v = c.C.First(); k != nil && !bytes.HasPrefix(k, c.Prefix); k, v = c.C.Next() {
+	}
+
+	if k == nil {
+		return nil, nil
+	}
+
+	if c.Reverse {
+		kc, vc := k, v
+		for ; kc != nil && bytes.HasPrefix(kc, c.Prefix); kc, vc = c.C.Next() {
+			k, v = kc, vc
+		}
+		if kc != nil {
+			k, v = c.C.Prev()
+		}
+	}
+
+	return k, v
+}
+
+// Next element
+func (c *PrefixCursor) Next() ([]byte, []byte) {
+	if c.Reverse {
+		return c.C.Prev()
+	}
+
+	return c.C.Next()
+}
+
+// Continue tells if the loop needs to continue
+func (c *PrefixCursor) Continue(val []byte) bool {
+	return val != nil && bytes.HasPrefix(val, c.Prefix)
+}