RandomSelection select(boolean narrow, boolean mixInNotPresentItems, boolean permitReversal) {
ThreadLocalRandom random = ThreadLocalRandom.current();
NavigableSet<Integer> canonicalSet = this.canonical;
BTreeSet<Integer> testAsSet = this.test;
List<Integer> canonicalList = new ArrayList<>(canonicalSet);
BTreeSet<Integer> testAsList = this.test;
Assert.assertEquals(canonicalSet.size(), testAsSet.size());
Assert.assertEquals(canonicalList.size(), testAsList.size());
// sometimes select keys first, so we cover full range
List<Integer> allKeys = randomKeys(canonical, mixInNotPresentItems);
List<Integer> keys = allKeys;
int narrowCount = random.nextInt(3);
while (narrow && canonicalList.size() > 10 && keys.size() > 10 && narrowCount-- > 0) {
boolean useLb = random.nextBoolean();
boolean useUb = random.nextBoolean();
if (!(useLb | useUb)) continue;
// select a range smaller than the total span when we have more narrowing iterations left
int indexRange = keys.size() / (narrowCount + 1);
boolean lbInclusive = true;
Integer lbKey = canonicalList.get(0);
int lbKeyIndex = 0, lbIndex = 0;
boolean ubInclusive = true;
Integer ubKey = canonicalList.get(canonicalList.size() - 1);
int ubKeyIndex = keys.size(), ubIndex = canonicalList.size();
if (useLb) {
lbKeyIndex = random.nextInt(0, indexRange - 1);
Integer candidate = keys.get(lbKeyIndex);
if (useLb = (candidate > lbKey && candidate <= ubKey)) {
lbInclusive = random.nextBoolean();
lbKey = keys.get(lbKeyIndex);
lbIndex = Collections.binarySearch(canonicalList, lbKey);
if (lbIndex >= 0 && !lbInclusive) lbIndex++;
else if (lbIndex < 0) lbIndex = -1 - lbIndex;
}
}
if (useUb) {
ubKeyIndex =
random.nextInt(Math.max(lbKeyIndex, keys.size() - indexRange), keys.size() - 1);
Integer candidate = keys.get(ubKeyIndex);
if (useUb = (candidate < ubKey && candidate >= lbKey)) {
ubInclusive = random.nextBoolean();
ubKey = keys.get(ubKeyIndex);
ubIndex = Collections.binarySearch(canonicalList, ubKey);
if (ubIndex >= 0 && ubInclusive) {
ubIndex++;
} else if (ubIndex < 0) ubIndex = -1 - ubIndex;
}
}
if (ubIndex < lbIndex) {
ubIndex = lbIndex;
ubKey = lbKey;
ubInclusive = false;
}
canonicalSet =
!useLb
? canonicalSet.headSet(ubKey, ubInclusive)
: !useUb
? canonicalSet.tailSet(lbKey, lbInclusive)
: canonicalSet.subSet(lbKey, lbInclusive, ubKey, ubInclusive);
testAsSet =
!useLb
? testAsSet.headSet(ubKey, ubInclusive)
: !useUb
? testAsSet.tailSet(lbKey, lbInclusive)
: testAsSet.subSet(lbKey, lbInclusive, ubKey, ubInclusive);
keys = keys.subList(lbKeyIndex, ubKeyIndex);
canonicalList = canonicalList.subList(lbIndex, ubIndex);
testAsList = testAsList.subList(lbIndex, ubIndex);
Assert.assertEquals(canonicalSet.size(), testAsSet.size());
Assert.assertEquals(canonicalList.size(), testAsList.size());
}
// possibly restore full set of keys, to test case where we are provided existing keys that
// are out of bounds
if (keys != allKeys && random.nextBoolean()) keys = allKeys;
Comparator<Integer> comparator = naturalOrder();
if (permitReversal && random.nextBoolean()) {
if (allKeys != keys) keys = new ArrayList<>(keys);
if (canonicalSet != canonical) canonicalList = new ArrayList<>(canonicalList);
Collections.reverse(keys);
Collections.reverse(canonicalList);
testAsList = testAsList.descendingSet();
canonicalSet = canonicalSet.descendingSet();
testAsSet = testAsSet.descendingSet();
comparator = reverseOrder();
}
Assert.assertEquals(canonicalSet.size(), testAsSet.size());
Assert.assertEquals(canonicalList.size(), testAsList.size());
if (!canonicalSet.isEmpty()) {
Assert.assertEquals(canonicalSet.first(), canonicalList.get(0));
Assert.assertEquals(canonicalSet.last(), canonicalList.get(canonicalList.size() - 1));
Assert.assertEquals(canonicalSet.first(), testAsSet.first());
Assert.assertEquals(canonicalSet.last(), testAsSet.last());
Assert.assertEquals(canonicalSet.first(), testAsList.get(0));
Assert.assertEquals(canonicalSet.last(), testAsList.get(testAsList.size() - 1));
}
return new RandomSelection(
keys, canonicalSet, testAsSet, canonicalList, testAsList, comparator);
}
