iter(g269): 新增文本差异对比组件

2026-10-26 22:53:49 +08:00
parent dccf79bb01
commit 368d47cbca
12 changed files with 304 additions and 11 deletions
@@ -0,0 +1,85 @@
+import { h } from '@ui-arch/frame';
+import type { DiffViewProps } from './types.js';
+
+// 一条差异：same 原样、add 只在右边、del 只在左边
+type DiffOp = { type: 'same' | 'add' | 'del'; text: string };
+// LCS 计算上限：中间段行数乘积超过这个值就退化为「整段替换」，避免大文件把主线程卡住
+const DP_LIMIT = 400_000;
+
+/*** 切行：末尾换行不产生一行空内容（否则每个文件都会多出一条假的空行差异） ***/
+function toLines(text: string): string[] {
+  const lines = text.split(/\r?\n/);
+  if (lines.length > 1 && lines[lines.length - 1] === '') lines.pop(); // 尾部换行忽略
+  return lines;
+}
+
+/*** 中间段做 LCS 对齐：先剪掉公共前后缀，剩下的才真算，日常改动只占几行 ***/
+function alignMiddle(a: string[], b: string[]): DiffOp[] {
+  if (!a.length || !b.length) return [...a.map((text) => ({ type: 'del' as const, text })), ...b.map((text) => ({ type: 'add' as const, text }))];
+  if (a.length * b.length > DP_LIMIT) return [...a.map((text) => ({ type: 'del' as const, text })), ...b.map((text) => ({ type: 'add' as const, text }))]; // 超限：整段替换，语义仍正确
+  const dp: number[][] = Array.from({ length: a.length + 1 }, () => new Array<number>(b.length + 1).fill(0)); // dp[i][j]：a 前 i 行与 b 前 j 行的 LCS 长度
+  for (let i = a.length - 1; i >= 0; i -= 1) {
+    for (let j = b.length - 1; j >= 0; j -= 1) {
+      dp[i][j] = a[i] === b[j] ? dp[i + 1][j + 1] + 1 : Math.max(dp[i + 1][j], dp[i][j + 1]);
+    }
+  }
+  const ops: DiffOp[] = [];
+  let i = 0;
+  let j = 0;
+  while (i < a.length && j < b.length) {
+    if (a[i] === b[j]) { ops.push({ type: 'same', text: a[i] }); i += 1; j += 1; continue; }
+    if (dp[i + 1][j] >= dp[i][j + 1]) { ops.push({ type: 'del', text: a[i] }); i += 1; continue; }
+    ops.push({ type: 'add', text: b[j] }); j += 1;
+  }
+  for (; i < a.length; i += 1) ops.push({ type: 'del', text: a[i] });
+  for (; j < b.length; j += 1) ops.push({ type: 'add', text: b[j] });
+  return ops;
+}
+
+/*** 逐行差异：剪公共前后缀后对齐中间段，输出完整 same / add / del 序列 ***/
+function diffLines(before: string, after: string): DiffOp[] {
+  const a = toLines(before);
+  const b = toLines(after);
+  let head = 0;
+  while (head < a.length && head < b.length && a[head] === b[head]) head += 1; // 公共前缀
+  let tail = 0;
+  while (tail < a.length - head && tail < b.length - head && a[a.length - 1 - tail] === b[b.length - 1 - tail]) tail += 1; // 公共后缀
+  const midA = a.slice(head, a.length - tail);
+  const midB = b.slice(head, b.length - tail);
+  return [
+    ...a.slice(0, head).map((text) => ({ type: 'same' as const, text })),
+    ...alignMiddle(midA, midB),
+    ...a.slice(a.length - tail).map((text) => ({ type: 'same' as const, text })),
+  ];
+}
+
+/*** 文本差异对比：行级对齐 + 增删着色 + 双行号列，超限时退化为整段替换（只影响精度不影响语义） ***/
+export function diffView(props: DiffViewProps): HTMLElement {
+  const ops = diffLines(props.before, props.after);
+  const added = ops.filter((o) => o.type === 'add').length; // 新增行数：统计条与读屏共用
+  const removed = ops.filter((o) => o.type === 'del').length; // 删除行数
+  let oldNo = 0;
+  let newNo = 0;
+  const rows = ops.map((op) => {
+    if (op.type !== 'add') oldNo += 1; // same 与 del 占旧行号
+    if (op.type !== 'del') newNo += 1; // same 与 add 占新行号
+    const sign = op.type === 'add' ? '+' : op.type === 'del' ? '−' : ' ';
+    return h(
+      'div',
+      { class: `ua-diff-row is-${op.type}` },
+      h('span', { class: 'ua-diff-no' }, op.type === 'add' ? '' : String(oldNo)),
+      h('span', { class: 'ua-diff-no' }, op.type === 'del' ? '' : String(newNo)),
+      h('span', { class: 'ua-diff-sign', 'aria-hidden': 'true' }, sign),
+      h('span', { class: 'ua-diff-text' }, op.text || ' '),
+    );
+  });
+  const stats = props.showStats === false
+    ? null
+    : h('div', { class: 'ua-diff-stats' }, h('span', { class: 'ua-diff-add' }, `+${added}`), h('span', { class: 'ua-diff-del' }, `−${removed}`));
+  return h(
+    'div',
+    { class: 'ua-diff', role: 'group', 'aria-label': props.ariaLabel ?? `文本差异：新增 ${added} 行，删除 ${removed} 行` },
+    stats,
+    h('div', { class: 'ua-diff-body' }, ...rows),
+  );
+}
@@ -78,3 +78,4 @@ export { highlight } from './highlight.js';
 export { inputTag } from './inputTag.js';
 export { layout } from './layout.js';
 export { jsonViewer } from './jsonViewer.js';
+export { diffView } from './diffView.js';
@@ -1030,3 +1030,11 @@ export interface JsonViewerProps {
  maxHeight?: number;              // 最高高度（px），超出在框内滚动；缺省不限高
  ariaLabel?: string;              // 可访问名；缺省「JSON 数据」
 }
+
+/*** 文本差异对比入参 ***/
+export interface DiffViewProps {
+  before: string;                  // 旧文本（按行比对，CRLF 与 LF 等价）
+  after: string;                   // 新文本
+  showStats?: boolean;             // 是否在顶部显示 +N / −N 统计条；缺省 true
+  ariaLabel?: string;              // 可访问名；缺省自动播报「新增 N 行，删除 M 行」
+}