Don't store collection reference in DeckTreeNode

Pass it in to processChildren() instead, which is cleaner, and will
work better with the move to a backend method.

AnkiDroid/src/main/java/com/ichi2/libanki/sched/AbstractDeckTreeNode.kt

@@ -32,7 +32,6 @@ import java.util.*
  * [processChildren] should be called if the children of this node are modified.
  */
 abstract class AbstractDeckTreeNode(
-    val col: Collection,
     /**
      * @return The full deck name, e.g. "A::B::C"
      */
@@ -68,7 +67,7 @@ abstract class AbstractDeckTreeNode(
         )
     }
 
-    abstract fun processChildren(children: List<AbstractDeckTreeNode>, addRev: Boolean)
+    abstract fun processChildren(col: Collection, children: List<AbstractDeckTreeNode>, addRev: Boolean)
 
     override fun toString(): String {
         val buf = StringBuffer()

AnkiDroid/src/main/java/com/ichi2/libanki/sched/DeckDueTreeNode.kt

@@ -34,7 +34,7 @@ import kotlin.math.min
  */
 @KotlinCleanup("maybe possible to remove gettres for revCount/lrnCount")
 @KotlinCleanup("rename name -> fullDeckName")
-class DeckDueTreeNode(col: Collection, name: String, did: Long, override var revCount: Int, override var lrnCount: Int, override var newCount: Int) : AbstractDeckTreeNode(col, name, did) {
+class DeckDueTreeNode(name: String, did: Long, override var revCount: Int, override var lrnCount: Int, override var newCount: Int) : AbstractDeckTreeNode(name, did) {
     override fun toString(): String {
         return String.format(
             Locale.US, "%s, %d, %d, %d, %d",
@@ -50,7 +50,7 @@ class DeckDueTreeNode(col: Collection, name: String, did: Long, override var rev
         newCount = max(0, min(newCount, limit))
     }
 
-    override fun processChildren(children: List<AbstractDeckTreeNode>, addRev: Boolean) {
+    override fun processChildren(col: Collection, children: List<AbstractDeckTreeNode>, addRev: Boolean) {
         // tally up children counts
         for (ch in children) {
             lrnCount += ch.lrnCount

AnkiDroid/src/main/java/com/ichi2/libanki/sched/DeckTreeNode.kt

@@ -16,11 +16,11 @@
 package com.ichi2.libanki.sched
 
 import com.ichi2.libanki.Collection
-import com.ichi2.utils.KotlinCleanup
+import net.ankiweb.rsdroid.RustCleanup
 
-@KotlinCleanup("confusing nullability for col, verify real nullability after code related to scheduling is fully migrated to kotlin")
-class DeckTreeNode(col: Collection, name: String, did: Long) : AbstractDeckTreeNode(col, name, did) {
-    override fun processChildren(children: List<AbstractDeckTreeNode>, addRev: Boolean) {
+@RustCleanup("processChildren() can be removed after migrating to backend implementation")
+class DeckTreeNode(name: String, did: Long) : AbstractDeckTreeNode(name, did) {
+    override fun processChildren(col: Collection, children: List<AbstractDeckTreeNode>, addRev: Boolean) {
         // intentionally blank
     }
 }

AnkiDroid/src/main/java/com/ichi2/libanki/sched/Sched.java

@@ -242,7 +242,7 @@ private void unburyCardsForDeck(@NonNull List<Long> allDecks) {
             // reviews
             int rev = _revForDeck(deck.getLong("id"), rlim);
             // save to list
-            deckNodes.add(new DeckDueTreeNode(getCol(), deck.getString("name"), deck.getLong("id"), rev, lrn, _new));
+            deckNodes.add(new DeckDueTreeNode(deck.getString("name"), deck.getLong("id"), rev, lrn, _new));
             // add deck as a parent
             lims.put(Decks.normalizeName(deck.getString("name")), new Integer[]{nlim, rlim});
         }

AnkiDroid/src/main/java/com/ichi2/libanki/sched/SchedV2.java

@@ -561,7 +561,7 @@ protected int _walkingCount(@NonNull LimitMethod limFn, @NonNull CountMethod cnt
             int rlim = _deckRevLimitSingle(deck, plim, false);
             int rev = _revForDeck(deck.getLong("id"), rlim, childMap);
             // save to list
-            deckNodes.add(new DeckDueTreeNode(getCol(), deck.getString("name"), deck.getLong("id"), rev, lrn, _new));
+            deckNodes.add(new DeckDueTreeNode(deck.getString("name"), deck.getLong("id"), rev, lrn, _new));
             // add deck as a parent
             lims.put(Decks.normalizeName(deck.getString("name")), new Integer[]{nlim, rlim});
         }
@@ -580,7 +580,7 @@ protected int _walkingCount(@NonNull LimitMethod limFn, @NonNull CountMethod cnt
         // Similar to deckDueList
         ArrayList<DeckTreeNode> allDecksSorted = new ArrayList<>();
         for (JSONObject deck : getCol().getDecks().allSorted()) {
-            DeckTreeNode g = new DeckTreeNode(getCol(), deck.getString("name"), deck.getLong("id"));
+            DeckTreeNode g = new DeckTreeNode(deck.getString("name"), deck.getLong("id"));
             allDecksSorted.add(g);
         }
         // End of the similar part.
@@ -666,7 +666,7 @@ public List<TreeNode<DeckDueTreeNode>> deckDueTree(@Nullable CancelListener canc
             TreeNode<T> toAdd = new TreeNode<>(child);
             toAdd.getChildren().addAll(childrenNode);
             List<T> childValues = childrenNode.stream().map(TreeNode::getValue).collect(Collectors.toList());
-            child.processChildren(childValues, "std".equals(getName()));
+            child.processChildren(mCol, childValues, "std".equals(getName()));
 
             sortedChildren.add(toAdd);
         }

AnkiDroid/src/test/java/com/ichi2/libanki/sched/SchedV2Test.java

@@ -112,16 +112,16 @@ protected static List<TreeNode<DeckDueTreeNode>> expectedTree(Collection col, bo
         // These matched the previous Java data
         // These may want to be changed back
         List<TreeNode<DeckDueTreeNode>> expected = new ArrayList<>();
-        DeckDueTreeNode caz = new DeckDueTreeNode(col, "cmxieunwoogyxsctnjmv::abcdefgh::ZYXW", 1596783600480L, 0, 0, 0);
-        DeckDueTreeNode ca = new DeckDueTreeNode(col, "cmxieunwoogyxsctnjmv::abcdefgh", 1596783600460L, 0, 0, 0);
-        DeckDueTreeNode ci = new DeckDueTreeNode(col, "cmxieunwoogyxsctnjmv::INSBGDS", 1596783600500L, 0, 0, 0);
-        DeckDueTreeNode c = new DeckDueTreeNode(col, "cmxieunwoogyxsctnjmv", 1596783600440L, 0, 0, 0);
-        DeckDueTreeNode defaul = new DeckDueTreeNode(col, "Default", 1, 0, 0, 0);
-        DeckDueTreeNode s = new DeckDueTreeNode(col, "scxipjiyozczaaczoawo", 1596783600420L, 0, 0, 0);
-        DeckDueTreeNode f = new DeckDueTreeNode(col, "blank::foobar", 1596783600540L, 0, 0, 0);
-        DeckDueTreeNode b = new DeckDueTreeNode(col, "blank", 1596783600520L, 0, 0, 0);
-        DeckDueTreeNode aBlank = new DeckDueTreeNode(col, "A::blank", 1596783600580L, 0, 0, 0);
-        DeckDueTreeNode a = new DeckDueTreeNode(col, "A", 1596783600560L, 0, 0, 0);
+        DeckDueTreeNode caz = new DeckDueTreeNode("cmxieunwoogyxsctnjmv::abcdefgh::ZYXW", 1596783600480L, 0, 0, 0);
+        DeckDueTreeNode ca = new DeckDueTreeNode("cmxieunwoogyxsctnjmv::abcdefgh", 1596783600460L, 0, 0, 0);
+        DeckDueTreeNode ci = new DeckDueTreeNode("cmxieunwoogyxsctnjmv::INSBGDS", 1596783600500L, 0, 0, 0);
+        DeckDueTreeNode c = new DeckDueTreeNode("cmxieunwoogyxsctnjmv", 1596783600440L, 0, 0, 0);
+        DeckDueTreeNode defaul = new DeckDueTreeNode("Default", 1, 0, 0, 0);
+        DeckDueTreeNode s = new DeckDueTreeNode("scxipjiyozczaaczoawo", 1596783600420L, 0, 0, 0);
+        DeckDueTreeNode f = new DeckDueTreeNode("blank::foobar", 1596783600540L, 0, 0, 0);
+        DeckDueTreeNode b = new DeckDueTreeNode("blank", 1596783600520L, 0, 0, 0);
+        DeckDueTreeNode aBlank = new DeckDueTreeNode("A::blank", 1596783600580L, 0, 0, 0);
+        DeckDueTreeNode a = new DeckDueTreeNode("A", 1596783600560L, 0, 0, 0);
 
 
         TreeNode<DeckDueTreeNode> cazNode = new TreeNode<>(caz);
@@ -135,23 +135,23 @@ protected static List<TreeNode<DeckDueTreeNode>> expectedTree(Collection col, bo
 
         // add "caz" to "ca"
         caNode.getChildren().add(cazNode);
-        caNode.getValue().processChildren(Collections.singletonList(cazNode.getValue()), addRev);
+        caNode.getValue().processChildren(col, Collections.singletonList(cazNode.getValue()), addRev);
 
         // add "ca" and "ci" to "c"
         cNode.getChildren().add(caNode);
         cNode.getChildren().add(ciNode);
         ArrayList<DeckDueTreeNode> cChildren = new ArrayList<>();
         cChildren.add(caNode.getValue());
         cChildren.add(ciNode.getValue());
-        cNode.getValue().processChildren(cChildren, addRev);
+        cNode.getValue().processChildren(col, cChildren, addRev);
 
         // add "f" to "b"
         bNode.getChildren().add(fNode);
-        bNode.getValue().processChildren(Collections.singletonList(fNode.getValue()), addRev);
+        bNode.getValue().processChildren(col, Collections.singletonList(fNode.getValue()), addRev);
 
         // add "A::" to "A"
         aNode.getChildren().add(aBlankNode);
-        aNode.getValue().processChildren(Collections.singletonList(aBlankNode.getValue()), addRev);
+        aNode.getValue().processChildren(col, Collections.singletonList(aBlankNode.getValue()), addRev);
 
         expected.add(aNode);
         expected.add(bNode);