add union/intersection for ValueSubkeyRange lists, and some tests

veilid-flutter/lib/value_subkey_range.dart

@@ -15,6 +15,10 @@ class ValueSubkeyRange with _$ValueSubkeyRange {
 
   factory ValueSubkeyRange.single(int val) =>
       ValueSubkeyRange(low: val, high: val);
+  factory ValueSubkeyRange.make(int low, int high) =>
+      ValueSubkeyRange(low: low, high: high);
+  factory ValueSubkeyRange.fromIntPair((int, int) pair) =>
+      ValueSubkeyRange(low: pair.$1, high: pair.$2);
 
   factory ValueSubkeyRange.fromJson(dynamic json) =>
       _$ValueSubkeyRangeFromJson(json as Map<String, dynamic>);
@@ -49,9 +53,20 @@ extension ValueSubkeyRangeExt on ValueSubkeyRange {
     return ValueSubkeyRange(
         low: max(low, other.low), high: min(high, other.high));
   }
+
+  ValueSubkeyRange? union(ValueSubkeyRange other) {
+    if (high < (other.low - 1) || low > (other.high + 1)) {
+      return null;
+    }
+    return ValueSubkeyRange(
+        low: min(low, other.low), high: max(high, other.high));
+  }
 }
 
 extension ListValueSubkeyRangeExt on List<ValueSubkeyRange> {
+  static List<ValueSubkeyRange> fromIntPairs(List<(int, int)> x) =>
+      x.map(ValueSubkeyRange.fromIntPair).toList();
+
   void validate() {
     int? lastHigh;
     for (final r in this) {
@@ -107,4 +122,32 @@ extension ListValueSubkeyRangeExt on List<ValueSubkeyRange> {
     }
     return out;
   }
+
+  List<ValueSubkeyRange> unionSubkeys(List<ValueSubkeyRange> other) {
+    final out = <ValueSubkeyRange>[];
+    ValueSubkeyRange? current;
+    for (var i = 0, j = 0; i < length || j < other.length;) {
+      if (i == length) {
+        current = other[j];
+        j++;
+      } else if (j == other.length) {
+        current = this[i];
+        i++;
+      } else if (this[i].low < other[j].low) {
+        current = this[i];
+        i++;
+      } else {
+        current = other[j];
+        j++;
+      }
+
+      if (out.isNotEmpty && out.last.high >= (current.low - 1)) {
+        out[out.length - 1] = ValueSubkeyRange(
+            low: out.last.low, high: max(out.last.high, current.high));
+      } else {
+        out.add(current);
+      }
+    }
+    return out;
+  }
 }

veilid-flutter/test/test_value_subkey_range.dart

@@ -0,0 +1,69 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:veilid/value_subkey_range.dart';
+
+void expectCommute<T>(T? Function(T, T) func, T a, T b, T? c) {
+  expect(func(a, b), c);
+  expect(func(b, a), c);
+}
+
+ValueSubkeyRange? vsrUnion(ValueSubkeyRange a, ValueSubkeyRange b) =>
+    a.union(b);
+
+ValueSubkeyRange? vsrIntersect(ValueSubkeyRange a, ValueSubkeyRange b) =>
+    a.intersect(b);
+
+List<ValueSubkeyRange> lvsrUnion(
+        List<ValueSubkeyRange> a, List<ValueSubkeyRange> b) =>
+    a.unionSubkeys(b);
+
+List<ValueSubkeyRange> lvsrIntersect(
+        List<ValueSubkeyRange> a, List<ValueSubkeyRange> b) =>
+    a.intersectSubkeys(b);
+
+Future<void> testValueSubkeyRange() async {
+  final a = ValueSubkeyRange.single(1);
+  const b = ValueSubkeyRange(low: 2, high: 3);
+  const c = ValueSubkeyRange(low: 3, high: 4);
+
+  expectCommute(vsrUnion, a, a, a);
+  expectCommute(vsrUnion, a, b, const ValueSubkeyRange(low: 1, high: 3));
+  expectCommute<ValueSubkeyRange>(vsrUnion, a, c, null);
+  expectCommute(vsrUnion, b, c, const ValueSubkeyRange(low: 2, high: 4));
+
+  const d = ValueSubkeyRange(low: 0, high: 3);
+
+  expectCommute<ValueSubkeyRange>(vsrIntersect, a, b, null);
+  expectCommute(vsrIntersect, c, d, ValueSubkeyRange.single(3));
+  expectCommute(vsrIntersect, d, d, d);
+}
+
+Future<void> testValueSubkeyRangeList() async {
+  final a = [ValueSubkeyRange.single(1)];
+  final b = [ValueSubkeyRange.fromIntPair((2, 3))];
+  final c = [ValueSubkeyRange.make(3, 4)];
+
+  expectCommute(lvsrUnion, a, a, a);
+  expectCommute(lvsrUnion, a, b, [const ValueSubkeyRange(low: 1, high: 3)]);
+  expectCommute<List<ValueSubkeyRange>>(
+      lvsrUnion, a, c, ListValueSubkeyRangeExt.fromIntPairs([(1, 1), (3, 4)]));
+  expectCommute(lvsrUnion, b, c, [const ValueSubkeyRange(low: 2, high: 4)]);
+
+  const d = [ValueSubkeyRange(low: 0, high: 3)];
+
+  expectCommute(lvsrIntersect, a, b, <ValueSubkeyRange>[]);
+  expectCommute(lvsrIntersect, c, d, [ValueSubkeyRange.single(3)]);
+  expectCommute(lvsrIntersect, d, d, d);
+
+  final e = ListValueSubkeyRangeExt.fromIntPairs([(1, 5), (10, 14), (16, 18)]);
+  final f = ListValueSubkeyRangeExt.fromIntPairs([(2, 6), (8, 10), (12, 20)]);
+  final g = ListValueSubkeyRangeExt.fromIntPairs([(1, 6), (8, 20)]);
+
+  expectCommute(lvsrUnion, e, f, g);
+
+  final h = ListValueSubkeyRangeExt.fromIntPairs(
+      [(2, 5), (10, 10), (12, 14), (16, 18)]);
+  expectCommute(lvsrIntersect, e, f, h);
+
+  expectCommute<List<ValueSubkeyRange>>(lvsrUnion, [], [], []);
+  expectCommute<List<ValueSubkeyRange>>(lvsrIntersect, [], [], []);
+}

veilid-flutter/test/veilid_test.dart

@@ -1,5 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'test_encoding.dart';
+import 'test_value_subkey_range.dart';
 
 void main() {
   TestWidgetsFlutterBinding.ensureInitialized();
@@ -11,4 +12,7 @@ void main() {
   test('testEncodingKnownVectors', testEncodingKnownVectors);
   test('testEncodeDecodeGarbage', testEncodeDecodeGarbage);
   test('testEncodeDecodeGarbagePad', testEncodeDecodeGarbagePad);
+
+  test('testVSR', testValueSubkeyRange);
+  test('test List<ValueSubkeyRange>', testValueSubkeyRangeList);
 }