Commit 8e90f62f authored by Kirill Smelkov's avatar Kirill Smelkov

go/zodb/btree: Add KeyRange type

KeyRange represents [lo,hi) key range. It simplifies working with ranges
of keys. We will use it in the next commit.

KeyRange originated in WCFS and was copied from there:

https://lab.nexedi.com/kirr/wendelin.core/blob/57be0126/wcfs/internal/xbtree/blib/keyrange.go
parent e829e4c8
......@@ -102,6 +102,12 @@ type BucketEntry struct {
value interface{}
}
// KeyRange represents [lo,hi) key range.
type KeyRange struct {
Lo KEY
Hi_ KEY // NOTE _not_ hi) to avoid overflow at ∞; hi = hi_ + 1
}
const _KeyMin KEY = math.Min<Key>
const _KeyMax KEY = math.Max<Key>
......@@ -641,3 +647,44 @@ func init() {
zodb.RegisterClass("BTrees.BTree.BTree", t(BTree{}), t(btreeState{}))
zodb.RegisterClass("BTrees.BTree.Bucket", t(Bucket{}), t(bucketState{}))
}
// ---- misc ----
// Has returns whether key k belongs to the range.
func (r *KeyRange) Has(k KEY) bool {
return (r.Lo <= k && k <= r.Hi_)
}
// Empty returns whether key range is empty.
func (r *KeyRange) Empty() bool {
hi := r.Hi_
if hi == _KeyMax {
// [x,∞] cannot be empty because max x is ∞ and [∞,∞] has one element: ∞
return false
}
hi++ // no overflow
return r.Lo >= hi
}
func (r KeyRange) String() string {
var shi string
if r.Hi_ == _KeyMax {
shi = kstr(r.Hi_) // ∞
} else {
shi = fmt.Sprintf("%d", r.Hi_+1)
}
return fmt.Sprintf("[%s,%s)", kstr(r.Lo), shi)
}
// kstr formats key as string.
func kstr(k KEY) string {
if k == _KeyMin {
return "-∞"
}
if k == _KeyMax {
return "∞"
}
return fmt.Sprintf("%d", k)
}
......@@ -29,6 +29,7 @@ kind=${KIND,,} # IO -> io
Key=${KEY^}
KEYKIND=${KIND:0:1} # IO -> I
keykind=${KEYKIND,,} # I -> i
input=$(dirname $0)/btree.go.in
......@@ -49,4 +50,6 @@ sed \
-e "s/\bbucketState\b/${kind}bucketState/g" \
-e "s/\b_KeyMin\b/_${KEYKIND}KeyMin/g" \
-e "s/\b_KeyMax\b/_${KEYKIND}KeyMax/g" \
-e "s/\bKeyRange\b/${KEYKIND}KeyRange/g" \
-e "s/\bkstr\b/${keykind}kstr/g" \
$input >>$out
......@@ -104,6 +104,12 @@ type IOBucketEntry struct {
value interface{}
}
// IKeyRange represents [lo,hi) key range.
type IKeyRange struct {
Lo int32
Hi_ int32 // NOTE _not_ hi) to avoid overflow at ∞; hi = hi_ + 1
}
const _IKeyMin int32 = math.MinInt32
const _IKeyMax int32 = math.MaxInt32
......@@ -643,3 +649,44 @@ func init() {
zodb.RegisterClass("BTrees.IOBTree.IOBTree", t(IOBTree{}), t(iobtreeState{}))
zodb.RegisterClass("BTrees.IOBTree.IOBucket", t(IOBucket{}), t(iobucketState{}))
}
// ---- misc ----
// Has returns whether key k belongs to the range.
func (r *IKeyRange) Has(k int32) bool {
return (r.Lo <= k && k <= r.Hi_)
}
// Empty returns whether key range is empty.
func (r *IKeyRange) Empty() bool {
hi := r.Hi_
if hi == _IKeyMax {
// [x,∞] cannot be empty because max x is ∞ and [∞,∞] has one element: ∞
return false
}
hi++ // no overflow
return r.Lo >= hi
}
func (r IKeyRange) String() string {
var shi string
if r.Hi_ == _IKeyMax {
shi = ikstr(r.Hi_) // ∞
} else {
shi = fmt.Sprintf("%d", r.Hi_+1)
}
return fmt.Sprintf("[%s,%s)", ikstr(r.Lo), shi)
}
// ikstr formats key as string.
func ikstr(k int32) string {
if k == _IKeyMin {
return "-∞"
}
if k == _IKeyMax {
return "∞"
}
return fmt.Sprintf("%d", k)
}
......@@ -104,6 +104,12 @@ type LOBucketEntry struct {
value interface{}
}
// LKeyRange represents [lo,hi) key range.
type LKeyRange struct {
Lo int64
Hi_ int64 // NOTE _not_ hi) to avoid overflow at ∞; hi = hi_ + 1
}
const _LKeyMin int64 = math.MinInt64
const _LKeyMax int64 = math.MaxInt64
......@@ -643,3 +649,44 @@ func init() {
zodb.RegisterClass("BTrees.LOBTree.LOBTree", t(LOBTree{}), t(lobtreeState{}))
zodb.RegisterClass("BTrees.LOBTree.LOBucket", t(LOBucket{}), t(lobucketState{}))
}
// ---- misc ----
// Has returns whether key k belongs to the range.
func (r *LKeyRange) Has(k int64) bool {
return (r.Lo <= k && k <= r.Hi_)
}
// Empty returns whether key range is empty.
func (r *LKeyRange) Empty() bool {
hi := r.Hi_
if hi == _LKeyMax {
// [x,∞] cannot be empty because max x is ∞ and [∞,∞] has one element: ∞
return false
}
hi++ // no overflow
return r.Lo >= hi
}
func (r LKeyRange) String() string {
var shi string
if r.Hi_ == _LKeyMax {
shi = lkstr(r.Hi_) // ∞
} else {
shi = fmt.Sprintf("%d", r.Hi_+1)
}
return fmt.Sprintf("[%s,%s)", lkstr(r.Lo), shi)
}
// lkstr formats key as string.
func lkstr(k int64) string {
if k == _LKeyMin {
return "-∞"
}
if k == _LKeyMax {
return "∞"
}
return fmt.Sprintf("%d", k)
}
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment