perf(grid): scan all-null columns once

apps/desktop/src/lib/dataGrid/dataGridColumnVisibility.ts

@@ -53,7 +53,22 @@ export function invertedHiddenColumnIndexes(availableIndexes: number[], hiddenIn
 
 export function allNullColumnIndexes(rows: ReadonlyArray<ReadonlyArray<unknown>>, availableIndexes: number[]): number[] {
   if (rows.length === 0) return [];
-  return availableIndexes.filter((index) => rows.every((row) => row[index] === null));
+  // 单遍行扫描 + 候选原地压缩：列一旦见到非 null 即永久剔除，候选清空提前
+  // 返回。最坏复杂度同为 O(列×行)（全 null 时无法避免），改进在于常数项：
+  // 原实现逐列 rows.every 各自从头扫外层 rows 并逐格调用回调，这里每个
+  // 单元格至多访问一次且无闭包调用
+  const candidates = [...availableIndexes];
+  let count = candidates.length;
+  for (const row of rows) {
+    let write = 0;
+    for (let read = 0; read < count; read++) {
+      if (row[candidates[read]!] === null) candidates[write++] = candidates[read]!;
+    }
+    count = write;
+    if (count === 0) return [];
+  }
+  candidates.length = count;
+  return candidates;
 }
 
 export function hiddenColumnIndexesWithAllNullColumns(options: { availableIndexes: number[]; hiddenIndexes: ReadonlySet<number>; allNullIndexes: ReadonlySet<number> }): { hiddenIndexes: Set<number>; autoHiddenIndexes: Set<number> } {

packages/app-tests/dataGridColumnVisibility.test.ts

@@ -97,6 +97,22 @@ test("finds columns where every row is NULL", () => {
   assert.deepEqual(indexes, [1, 2]);
 });
 
+test("all-null scan handles sparse, ragged and non-candidate columns", () => {
+  // 前缀多 null 但尾行非 null 的列必须被剔除；availableIndexes 之外的列不参与
+  const rows = [
+    [null, 1, null, null],
+    [null, null, null, null],
+    [null, null, 2, null],
+  ];
+  assert.deepEqual(allNullColumnIndexes(rows, [0, 1, 2]), [0]);
+  // 不等宽行：短行缺失的单元格为 undefined ≠ null，剔除该列（与原实现一致）
+  assert.deepEqual(allNullColumnIndexes([[null, null], [null]], [0, 1]), [0]);
+  // 全部候选都非 null：提前收敛返回空
+  assert.deepEqual(allNullColumnIndexes([[1, 2]], [0, 1]), []);
+  // 乱序候选：返回顺序保持 availableIndexes 原序
+  assert.deepEqual(allNullColumnIndexes([[null, 1, null]], [2, 0]), [2, 0]);
+});
+
 test("does not treat empty results as all-null columns", () => {
   assert.deepEqual(allNullColumnIndexes([], [0, 1, 2]), []);
 });