perf: 优化列表操作预测算法

DUpdateSystem · Sep 22, 2020 · 55a4dfd · 55a4dfd
1 parent b6ab52a
commit 55a4dfd
Showing 1 changed file with 23 additions and 5 deletions.
diff --git a/app/src/main/java/net/xzos/upgradeall/utils/ListUtils.kt b/app/src/main/java/net/xzos/upgradeall/utils/ListUtils.kt
@@ -25,28 +25,46 @@ fun <E> list1ToList2(list1: List<E>, list2: List<E>): List<ListOperationStepBase
     }
     val tmpList = list1.toMutableList()
     val operationSteps = mutableListOf<ListOperationStepBase>()
+    // 删除多余项
     for (item in delList) {
         val index = tmpList.indexOf(item)
         operationSteps.add(ListDelOperationStep(index))
         tmpList.removeAt(index)
     }
+    // 添加缺失项
+    val addItemMap = hashMapOf<E, Int>()
     for (item in addList) {
         val index = list2.indexOf(item)
         if (index < tmpList.size) {
             tmpList.add(index, item)
-            operationSteps.add(ListAddOperationStep(index, item))
+            addItemMap[item] = index
         } else {
             tmpList.add(item)
-            operationSteps.add(ListAddOperationStep(tmpList.size - 1, item))
+            addItemMap[item] = tmpList.size - 1
         }
     }
+    // 还原位置
+    val swapItemMap = mutableMapOf<E, Pair<Int, Int>>()
     for (i in tmpList.indices) {
         val item = tmpList[i]
         val newIndex = list2.indexOf(item)
-        if (i != newIndex && newIndex < tmpList.size) {
+        if (i != newIndex) {
             tmpList[i] = tmpList[newIndex].also { tmpList[newIndex] = tmpList[i] }
-            operationSteps.add((ListSwapOperationStep(i, newIndex)))
+            if (item in addItemMap) {
+                addItemMap[item] = newIndex
+            } else {
+                swapItemMap[item]?.let {
+                    swapItemMap[item] = Pair(it.first, newIndex)
+                } ?: run { swapItemMap[item] = Pair(i, newIndex) }
+            }
         }
     }
+    val sorted = addItemMap.toList().sortedBy { (_, value) -> value }.toMap()
+    for ((item, index) in sorted.entries) {
+        operationSteps.add(ListAddOperationStep(index, item))
+    }
+    for ((_, index) in swapItemMap) {
+        operationSteps.add((ListSwapOperationStep(index.first, index.second)))
+    }
     return operationSteps
-}
+}