#228 Implementation of equals/hashCode of CubeId is fixed

core/src/main/scala/io/qbeast/core/model/CubeId.scala

@@ -6,7 +6,6 @@ package io.qbeast.core.model
 import io.qbeast.core.model.CubeId.{ChildrenIterator, Codec}
 
 import java.nio.ByteBuffer
-import java.util.Arrays
 import scala.collection.immutable.BitSet
 import scala.collection.mutable
 
@@ -95,20 +94,6 @@ object CubeId {
     containers(point).drop(depth).next()
   }
 
-  private def trimBitMask(bitMask: Array[Long]): Array[Long] = {
-    var last = bitMask.length - 1
-    while (last >= 0 && bitMask(last) == 0) {
-      last -= 1
-    }
-    if (last < bitMask.length - 1) {
-      val trimmedBitMask = new Array[Long](last + 1)
-      Array.copy(bitMask, 0, trimmedBitMask, 0, trimmedBitMask.length)
-      trimmedBitMask
-    } else {
-      bitMask
-    }
-  }
-
   private class ContainersIterator(point: Point, parent: Option[CubeId])
       extends Iterator[CubeId] {
 
@@ -270,14 +255,17 @@ case class CubeId(dimensionCount: Int, depth: Int, bitMask: Array[Long])
    *         is less than, equal to, or greater than the other CubeId.
    */
   override def compare(that: CubeId): Int = {
-    val thisBitset = BitSet.fromBitMaskNoCopy(bitMask)
-    val thatBitset = BitSet.fromBitMaskNoCopy(that.bitMask)
-    val commonDepth = math.min(depth, that.depth)
-    for (depthOffset <- 0.until(commonDepth * dimensionCount)) {
-      val firstBit = thisBitset.contains(depthOffset)
-      val secondBit = thatBitset.contains(depthOffset)
-      if (firstBit != secondBit) {
-        if (firstBit) {
+    require(
+      that.dimensionCount == dimensionCount,
+      "The two cubes must have the same dimension count.")
+    val thisBits = BitSet.fromBitMaskNoCopy(bitMask)
+    val thatBits = BitSet.fromBitMaskNoCopy(that.bitMask)
+    val end = dimensionCount * math.min(depth, that.depth)
+    for (i <- (0 until end)) {
+      val thisBit = thisBits.contains(i)
+      val thatBit = thatBits.contains(i)
+      if (thisBit != thatBit) {
+        if (thisBit) {
           return 1
         } else {
           return -1
@@ -302,14 +290,13 @@ case class CubeId(dimensionCount: Int, depth: Int, bitMask: Array[Long])
     require(
       other.dimensionCount == dimensionCount,
       "The two cubes must have the same dimension count.")
-
     if (depth > other.depth) {
-      false
-    } else {
-      val end = dimensionCount * depth
-      val ancestorBitMask = BitSet.fromBitMaskNoCopy(other.bitMask).until(end).toBitMask
-      Arrays.equals(CubeId.trimBitMask(bitMask), CubeId.trimBitMask(ancestorBitMask))
+      return false
     }
+    val end = dimensionCount * depth
+    val bits = BitSet.fromBitMaskNoCopy(bitMask)
+    val otherBits = BitSet.fromBitMask(other.bitMask).until(end)
+    bits == otherBits
   }
 
   /**
@@ -402,9 +389,8 @@ case class CubeId(dimensionCount: Int, depth: Int, bitMask: Array[Long])
 
   override def equals(obj: Any): Boolean = obj match {
     case other: CubeId =>
-      dimensionCount == other.dimensionCount && depth == other.depth && Arrays.equals(
-        CubeId.trimBitMask(bitMask),
-        CubeId.trimBitMask(other.bitMask))
+      dimensionCount == other.dimensionCount && depth == other.depth && BitSet.fromBitMaskNoCopy(
+        bitMask) == BitSet.fromBitMaskNoCopy(other.bitMask)
     case _ => false
   }
 
@@ -413,7 +399,7 @@ case class CubeId(dimensionCount: Int, depth: Int, bitMask: Array[Long])
     var result = 1
     result = prime * result + dimensionCount
     result = prime * result + depth
-    result = prime * result + Arrays.hashCode(CubeId.trimBitMask(bitMask))
+    result = prime * result + BitSet.fromBitMaskNoCopy(bitMask).hashCode()
     result
   }
 

core/src/test/scala/io/qbeast/core/model/CubeIdTest.scala

@@ -28,6 +28,10 @@ class CubeIdTest extends AnyFlatSpec with Matchers {
     val id7 =
       CubeId(2, "wQwwwQwwQwwQwwwwwQwQwwwQQwwwwQQwQwwwQwwQwwQwwwwwQwwQQQQQQQQQQQQQ")
     id6 == id7 shouldBe true
+    val id8 =
+      CubeId(1, 4, Array(9L)).parent.get.parent.get.parent.get
+    val id9 = CubeId(1, 1, Array(1L))
+    id8 == id9 shouldBe true
   }
 
   it should "implement hashCode correctly" in {
@@ -153,6 +157,13 @@ class CubeIdTest extends AnyFlatSpec with Matchers {
     id4.nextSibling shouldBe None
   }
 
+  it should "implement children iterator throwing NoSuchElementException after last child" in {
+    val children = CubeId.root(1).children
+    children.next() shouldBe CubeId.root(1).firstChild
+    children.next() shouldBe CubeId.root(1).firstChild.nextSibling.get
+    assertThrows[NoSuchElementException](children.next())
+  }
+
   it should "return a correct container with specified depth" in {
     val point = Point(0.66, 0.83)
     val id = CubeId.container(point, 2)

core/src/test/scala/io/qbeast/core/model/JSONSerializationTests.scala

@@ -1,6 +1,11 @@
 package io.qbeast.core.model
 
-import io.qbeast.core.transform.{HashTransformation, LinearTransformation, Transformation, Transformer}
+import io.qbeast.core.transform.{
+  HashTransformation,
+  LinearTransformation,
+  Transformation,
+  Transformer
+}
 import org.scalatest.flatspec.AnyFlatSpec
 import org.scalatest.matchers.should.Matchers