.

wcfs/internal/xbtree/pptreesubset.go

@@ -131,7 +131,16 @@ func (S PPTreeSubSet) AddPath(path []zodb.Oid) {
 	}
 }
 
-// ---- Union/Difference ----
+// ---- Union/Difference/Intersetctior ----
+
+// Union returns U = PP(A.leafs | B.leafs)
+//
+// In other words it returns sum of A and B.
+func (A PPTreeSubSet) Union(B PPTreeSubSet) PPTreeSubSet {
+	U := A.Clone()
+	U.UnionInplace(B)
+	return U
+}
 
 // UnionInplace sets A = PP(A.leafs | B.leafs)
 //
@@ -151,6 +160,8 @@ func (A PPTreeSubSet) UnionInplace(B PPTreeSubSet) {
 	A.xUnionInplace(B)
 }
 
+// XXX Difference
+
 // DifferenceInplace sets A = PP(A.leafs \ B.leafs)
 //
 // In other words it removes B nodes from A while still maintaining A as PP-connected.
@@ -169,6 +180,8 @@ func (A PPTreeSubSet) DifferenceInplace(B PPTreeSubSet) {
 	A.xDifferenceInplace(B)
 }
 
+// XXX Intersection
+
 func (A PPTreeSubSet) xUnionInplace(B PPTreeSubSet) {
 	if debugPPSet {
 		fmt.Printf("\n\n  xUnionInplace:\n")

wcfs/internal/xbtree/pptreesubset_test.go

@@ -33,8 +33,8 @@ func TestPPTreeSubSetOps(t *testing.T) {
 		d
 		ø = zodb.InvalidOid
 	)
-	type  S = PPTreeSubSet
-	type  testEntry struct {
+	type S = PPTreeSubSet
+	type testEntry struct {
 		A, B       S
 		Union      S
 		Difference S

wcfs/internal/xbtree/rangeset.go

+// Copyright (C) 2021  Nexedi SA and Contributors.
+//                     Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+package xbtree
+// set of [lo,hi) Key ranges.
+
+// Range represents [lo,hi) Key range.
+type Range struct {
+	lo  Key
+	hi_ Key // NOTE _not_ hi) to avoid overflow at ∞;  hi = hi_ + 1
+}
+
+// RangeSet is set of non-overlapping Key ranges.
+type RangeSet struct {
+	// TODO use BTree lo->hi_ instead
+	rangev []Range // lo↑
+}
+
+// Add adds Range r to the set of keys.
+func (S *RangeSet) Add(r Range) {
+	panic("TODO")	// XXX
+}
+
+// Del removes Range r from the set of keys.
+func (S *RangeSet) Del(r Range) {
+	panic("TODO")	// XXX
+}
+
+
+// XXX Has?
+
+
+// XXX AddKey ?
+// XXX DelKey ?
+// XXX HasKey
+
+// Union returns RangeSet(A.keys | B.keys).
+func (A *RangeSet) Union(B *RangeSet) *RangeSet {
+	U := A.Clone()
+	U.UnionInplace(B)
+	return U
+}
+
+// Difference returns RangeSet(A.keys \ B.keys).
+func (A *RangeSet) Difference(B *RangeSet) *RangeSet {
+	D := A.Clone()
+	D.DifferenceInplace(B)
+	return D
+}
+
+// XXX Intersection
+
+
+// --------
+
+// XXX RangeSet.verify to check ranges are not overlapping and ↑
+
+
+func (r Range) String() string {
+        slo  := "-∞";  if rn.lo  > KeyMin { slo = fmt.Sprintf("%v", rn.lo) }
+        shi  := "∞";   if rn.hi_ < KeyMax { shi = fmt.Sprintf("%v", rn.hi_+1) }
+	return fmt.Sprintf("[%s,%s)", slo, shi)
+}
+
+func (S RangeSet) String() string {
+	s := "{"
+	for i, r := range S.rangev {
+		if i > 0 {
+			s += " "
+		}
+		s += r.String()
+	}
+	s += "}"
+	return s
+}

wcfs/internal/xbtree/rangeset_test.go

+// Copyright (C) 2021  Nexedi SA and Contributors.
+//                     Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+package xbtree
+
+import (
+	"testing"
+)
+
+func TestRangeSet(t *testing.T) {
+	const (
+		oo  = KeyMax
+		noo = KeyMin
+	)
+
+	type testEntry struct {
+		A, B       *RangeSet
+		Union      *RangeSet
+		Difference *RangeSet
+	}
+	E := func(A, B, U, D *RangeSet) testEntry {
+		return testEntry{A, B, U, D}
+	}
+
+	// S is shorthand to create RangeSet, e.g. S(1,2, 4,5) will return {[1,2) [4,5)}
+	S := func(kv ...Key) *RangeSet {
+		l := len(kv)
+		if l % 2 != 0 {
+			panic("odd number of keys")
+		}
+		S := &RangeSet{}
+		for i := 0; i < l/2; i++ {
+			S.Add(Range{kv[2*i], kv[2*i+1]})
+		}
+		return S
+	}
+
+	testv := testEntry{
+		E(
+			S(),	// A
+			S(),	// B
+				S(),	// U
+				S()),	// D
+
+		E(
+			S(1,2),	// A
+			S(1,2),	// B
+				S(1,2),	// U
+				S()),	// D
+
+		// XXX
+	}
+}