pref(runtime-vapor): add fast path for append rows

Author: johnsoncodehk

packages/runtime-vapor/src/apiCreateFor.ts

@@ -198,84 +198,92 @@ export const createFor = (
           pendingNews[l1++] = [i, item, key]
         }
 
-        pendingNews.length = l1
-        oldKeyToIndex.length = l2
+        if (!l1 && !l2) {
+          for (let i = prepareLength; i < newLength - right; i++) {
+            const item = getItem(source, i)
+            const key = getKey.apply(null, item)
+            mount(source, i, item, key, defaultAnchor)
+          }
+        } else {
+          pendingNews.length = l1
+          oldKeyToIndex.length = l2
+
+          const oldKeyToIndexMap = new Map(oldKeyToIndex)
+          const pendingMounts: [
+            index: number,
+            item: ReturnType<typeof getItem>,
+            key: any,
+            anchorIndex: number,
+          ][] = []
+          const moveOrMount = (
+            index: number,
+            item: ReturnType<typeof getItem>,
+            key: any,
+            anchorIndex: number,
+          ) => {
+            const oldIndex = oldKeyToIndexMap.get(key)
+            if (oldIndex !== undefined) {
+              const block = (newBlocks[index] = oldBlocks[oldIndex])
+              update(block, ...item)
+              insert(
+                block,
+                parent!,
+                anchorIndex === -1
+                  ? defaultAnchor
+                  : normalizeAnchor(newBlocks[anchorIndex].nodes),
+              )
+              oldKeyToIndexMap.delete(key)
+            } else {
+              pendingMounts.push([index, item, key, anchorIndex])
+            }
+          }
 
-        const oldKeyToIndexMap = new Map(oldKeyToIndex)
-        const pendingMounts: [
-          index: number,
-          item: ReturnType<typeof getItem>,
-          key: any,
-          anchorIndex: number,
-        ][] = []
-        const moveOrMount = (
-          index: number,
-          item: ReturnType<typeof getItem>,
-          key: any,
-          anchorIndex: number,
-        ) => {
-          const oldIndex = oldKeyToIndexMap.get(key)
-          if (oldIndex !== undefined) {
-            const block = (newBlocks[index] = oldBlocks[oldIndex])
-            update(block, ...item)
-            insert(
-              block,
-              parent!,
-              anchorIndex === -1
-                ? defaultAnchor
-                : normalizeAnchor(newBlocks[anchorIndex].nodes),
+          for (let i = pendingNews.length - 1; i >= 0; i--) {
+            const [index, item, key] = pendingNews[i]
+            moveOrMount(
+              index,
+              item,
+              key,
+              index < prepareLength - 1 ? index + 1 : -1,
             )
-            oldKeyToIndexMap.delete(key)
-          } else {
-            pendingMounts.push([index, item, key, anchorIndex])
           }
-        }
 
-        for (let i = pendingNews.length - 1; i >= 0; i--) {
-          const [index, item, key] = pendingNews[i]
-          moveOrMount(
-            index,
-            item,
-            key,
-            index < prepareLength - 1 ? index + 1 : -1,
-          )
-        }
-
-        for (let i = prepareLength; i < newLength - right; i++) {
-          const item = getItem(source, i)
-          const key = getKey.apply(null, item)
-          moveOrMount(i, item, key, -1)
-        }
+          for (let i = prepareLength; i < newLength - right; i++) {
+            const item = getItem(source, i)
+            const key = getKey.apply(null, item)
+            moveOrMount(i, item, key, -1)
+          }
 
-        const shouldUseFastRemove = pendingMounts.length === newLength
+          const shouldUseFastRemove = pendingMounts.length === newLength
 
-        for (const i of oldKeyToIndexMap.values()) {
-          unmount(
-            oldBlocks[i],
-            !(shouldUseFastRemove && canUseFastRemove),
-            !shouldUseFastRemove,
-          )
-        }
-        if (shouldUseFastRemove) {
-          for (const selector of selectors) {
-            selector.cleanup()
+          for (const i of oldKeyToIndexMap.values()) {
+            unmount(
+              oldBlocks[i],
+              !(shouldUseFastRemove && canUseFastRemove),
+              !shouldUseFastRemove,
+            )
           }
-          if (canUseFastRemove) {
-            parent!.textContent = ''
-            parent!.appendChild(parentAnchor)
+          if (shouldUseFastRemove) {
+            for (const selector of selectors) {
+              selector.cleanup()
+            }
+            if (canUseFastRemove) {
+              parent!.textContent = ''
+              parent!.appendChild(parentAnchor)
+            }
           }
-        }
 
-        for (const [index, item, key, anchorIndex] of pendingMounts) {
-          mount(
-            source,
-            index,
-            item,
-            key,
-            anchorIndex === -1
-              ? defaultAnchor
-              : normalizeAnchor(newBlocks[anchorIndex].nodes),
-          )
+          for (const [index, item, key, anchorIndex] of pendingMounts) {
+            mount(
+              source,
+              index,
+              item,
+              key,
+              anchorIndex === -1
+                ? defaultAnchor
+                : normalizeAnchor(newBlocks[anchorIndex].nodes),
+            )
+          }
         }
       }
     }