Files
jiang13-bbs/frontend/lib/smartDiff.ts
freefire 5270fee2b7 feat: 评论/帖子编辑历史与编辑标记,内容锁定
- 新增 smartDiff 差异计算与 EditHistoryModal 编辑历史弹窗,替换原 CommentEditHistoryModal
- 新增 PostEditedMark 编辑标记展示
- 新增内容锁定机制(content_lock)防止并发编辑冲突
- 审核与通知服务适配
2026-09-25 23:41:45 +08:00

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/**
* smartDiff —— 面向可读性的结构化行级 diff(自研,无第三方依赖)。
*
* 四层处理:
* 1. 预处理:CRLF/CR → LF(仅用于比较与展示),行尾空白在比较时忽略(展示保留原文)。
* 2. 算法选择:行级相似度(difflib ratio 思路:2M/(a+b),M 为多重集交集)低于阈值时
* 判定「整段替换」,输出一个 block-replace,跳过逐行对齐——避免把毫无对应关系的
* 两段文本切成几十对 -/+ 碎片;否则用 Patience diff(锚定双方唯一行,LIS 选链),
* 无锚点/超大规模/超深递归的子区间回退为 LCS 或整块替换。
* 3. 后处理:相邻同向变更合并为一个块(del 在前 ins 在后),消除 LCS 的交叉配对;
* 上下文折叠(默认 3 行,头/尾块只保留单侧上下文)。
* 4. 行内细分:replace 块内按下标配对的行对,先分词(CJK 单字、西文单词、空白、符号),
* 词级 LCS 相似度 > 阈值时输出变更片段的字符偏移(segments),否则整行视为变更。
*
* 输出为结构化块数组,供 diff 视图组件渲染;segments 直接挂在对应行上
* (start/end 为该行文本的 UTF-16 偏移),UI 只高亮变更部分。
*/
export type LineOp = "equal" | "del" | "ins";
export type BlockType = "equal" | "insert" | "delete" | "replace" | "block-replace";
/** 行内变更片段:start/end 为行文本的 UTF-16 偏移,type 为该行视角下的变更方向 */
export interface InlineSegment {
start: number;
end: number;
type: "del" | "ins";
}
export interface DiffLine {
op: LineOp;
/** 原始行文本(保留行尾空白,供展示) */
text: string;
/** 仅 replace 块中被判定为「修改」的行对附带;缺省表示整行变更 */
segments?: InlineSegment[];
}
export interface DiffBlock {
type: BlockType;
lines: DiffLine[];
}
export interface DiffStats {
adds: number;
dels: number;
}
export interface DiffResult {
blocks: DiffBlock[];
stats: DiffStats;
}
export interface SmartDiffOptions {
/** 行级相似度低于该值判定整段替换(默认 0.2;仅任一侧 ≥2 行时生效) */
replaceThreshold?: number;
/** 行对词级相似度高于该值才做行内细分(默认 0.6) */
inlineThreshold?: number;
}
// 行级 LCS 回退的规模上限(超出则该区间整块替换,避免 O(n·m) 爆炸)
const MAX_REGION_CELLS = 400_000;
// 行内词级 LCS 的 token 数上限
const MAX_INLINE_CELLS = 20_000;
// 行对合计字符数超过则跳过行内细分
const MAX_INLINE_CHARS = 4_000;
// Patience 递归深度上限(超过直接整块替换,防御构造性深递归)
const MAX_PATIENCE_DEPTH = 32;
/* ---------------- 第一层:预处理 ---------------- */
interface SplitText {
raw: string[];
/** 归一化后的行(比较用):行尾空白已去除 */
cmp: string[];
}
function splitLines(text: string): SplitText {
const norm = text.replace(/\r\n?/g, "\n");
const raw = norm === "" ? [] : norm.split("\n");
return { raw, cmp: raw.map((l) => l.replace(/\s+$/, "")) };
}
/* ---------------- 第二层:相似度与算法选择 ---------------- */
/** 行级相似度:difflib ratio 思路,2M/(a+b),M 为行多重集交集大小 */
function lineSimilarity(a: string[], b: string[]): number {
if (a.length === 0 && b.length === 0) return 1;
const freq = new Map<string, number>();
for (const l of a) freq.set(l, (freq.get(l) ?? 0) + 1);
let m = 0;
for (const l of b) {
const c = freq.get(l) ?? 0;
if (c > 0) {
m += 1;
freq.set(l, c - 1);
}
}
return (2 * m) / (a.length + b.length);
}
type RawOp = { op: LineOp; ai: number; bi: number };
/**
* Patience diff:在区间内找到「双方都恰好出现一次」的公共行作锚点,
* 对锚点按 i 升序求 j 的最长递增子序列(patience sorting,O(k log k))作骨架,
* 骨架之间的间隙递归;无锚点/超深的区间回退 fallbackRegion。
*/
function patienceDiff(
cmpA: string[],
cmpB: string[],
loA: number,
hiA: number,
loB: number,
hiB: number,
out: RawOp[],
depth: number
): void {
if (loA >= hiA && loB >= hiB) return;
const countA = new Map<string, number>();
for (let i = loA; i < hiA; i++) countA.set(cmpA[i], (countA.get(cmpA[i]) ?? 0) + 1);
const countB = new Map<string, number>();
for (let j = loB; j < hiB; j++) countB.set(cmpB[j], (countB.get(cmpB[j]) ?? 0) + 1);
const posA = new Map<string, number>();
for (let i = loA; i < hiA; i++) {
if (countA.get(cmpA[i]) === 1) posA.set(cmpA[i], i);
}
const anchors: Array<{ i: number; j: number }> = [];
for (let j = loB; j < hiB; j++) {
if (countB.get(cmpB[j]) === 1) {
const i = posA.get(cmpB[j]);
if (i !== undefined) anchors.push({ i, j });
}
}
if (anchors.length === 0 || depth >= MAX_PATIENCE_DEPTH) {
fallbackRegion(cmpA, cmpB, loA, hiA, loB, hiB, out);
return;
}
anchors.sort((x, y) => x.i - y.i);
const tails: number[] = [];
const prev = new Array<number>(anchors.length).fill(-1);
for (let k = 0; k < anchors.length; k++) {
const j = anchors[k].j;
let lo = 0;
let hi = tails.length;
while (lo < hi) {
const mid = (lo + hi) >> 1;
if (anchors[tails[mid]].j < j) lo = mid + 1;
else hi = mid;
}
if (lo > 0) prev[k] = tails[lo - 1];
if (lo === tails.length) tails.push(k);
else tails[lo] = k;
}
const chain: number[] = [];
for (let k = tails[tails.length - 1]; k !== -1; k = prev[k]) chain.push(k);
chain.reverse();
let ai = loA;
let bi = loB;
for (const k of chain) {
const { i, j } = anchors[k];
patienceDiff(cmpA, cmpB, ai, i, bi, j, out, depth + 1);
out.push({ op: "equal", ai: i, bi: j });
ai = i + 1;
bi = j + 1;
}
patienceDiff(cmpA, cmpB, ai, hiA, bi, hiB, out, depth + 1);
}
/** 无锚点区间:无公共行或规模超限时整块替换;否则 LCS 细对齐 */
function fallbackRegion(
cmpA: string[],
cmpB: string[],
loA: number,
hiA: number,
loB: number,
hiB: number,
out: RawOp[]
): void {
const n = hiA - loA;
const m = hiB - loB;
if (n === 0 && m === 0) return;
if (n === 0) {
for (let j = loB; j < hiB; j++) out.push({ op: "ins", ai: loA, bi: j });
return;
}
if (m === 0) {
for (let i = loA; i < hiA; i++) out.push({ op: "del", ai: i, bi: loB });
return;
}
if (n * m > MAX_REGION_CELLS || !hasCommonLine(cmpA, cmpB, loA, hiA, loB, hiB)) {
for (let i = loA; i < hiA; i++) out.push({ op: "del", ai: i, bi: loB });
for (let j = loB; j < hiB; j++) out.push({ op: "ins", ai: hiA, bi: j });
return;
}
lcsRegion(cmpA, cmpB, loA, hiA, loB, hiB, out);
}
function hasCommonLine(
cmpA: string[],
cmpB: string[],
loA: number,
hiA: number,
loB: number,
hiB: number
): boolean {
const set = new Set<string>();
for (let i = loA; i < hiA; i++) set.add(cmpA[i]);
for (let j = loB; j < hiB; j++) {
if (set.has(cmpB[j])) return true;
}
return false;
}
/** 行级 LCS(规模已由调用方限制),供无锚点但有公共行的区间使用 */
function lcsRegion(
cmpA: string[],
cmpB: string[],
loA: number,
hiA: number,
loB: number,
hiB: number,
out: RawOp[]
): void {
const n = hiA - loA;
const m = hiB - loB;
const width = m + 1;
const dp = new Uint32Array((n + 1) * width);
for (let i = n - 1; i >= 0; i--) {
const aLine = cmpA[loA + i];
for (let j = m - 1; j >= 0; j--) {
dp[i * width + j] =
aLine === cmpB[loB + j]
? dp[(i + 1) * width + (j + 1)] + 1
: Math.max(dp[(i + 1) * width + j], dp[i * width + (j + 1)]);
}
}
let i = 0;
let j = 0;
while (i < n && j < m) {
if (cmpA[loA + i] === cmpB[loB + j]) {
out.push({ op: "equal", ai: loA + i, bi: loB + j });
i += 1;
j += 1;
} else if (dp[(i + 1) * width + j] >= dp[i * width + (j + 1)]) {
out.push({ op: "del", ai: loA + i, bi: loB + j });
i += 1;
} else {
out.push({ op: "ins", ai: loA + i, bi: loB + j });
j += 1;
}
}
while (i < n) {
out.push({ op: "del", ai: loA + i, bi: loB + j });
i += 1;
}
while (j < m) {
out.push({ op: "ins", ai: loA + i, bi: loB + j });
j += 1;
}
}
/* ---------------- 第三层:后处理(块构建 + 上下文折叠) ---------------- */
/**
* 把扁平 op 序列整理成块:
* - 连续 equal → equal 块(展示用旧文本原文)
* - 连续非 equal 合并为一个变更区域:del 按原顺序在前、ins 按新顺序在后,
* 两侧都有 → replace(后续做行内细分),单侧 → delete / insert。
* 这一步消除了 LCS 可能出现的 -/+ 交叉碎片(del,ins,del,ins → 一个 replace 块)。
*/
function buildBlocks(ops: RawOp[], rawA: string[], rawB: string[]): DiffBlock[] {
const blocks: DiffBlock[] = [];
let k = 0;
while (k < ops.length) {
if (ops[k].op === "equal") {
const lines: DiffLine[] = [];
while (k < ops.length && ops[k].op === "equal") {
lines.push({ op: "equal", text: rawA[ops[k].ai] });
k += 1;
}
blocks.push({ type: "equal", lines });
continue;
}
const dels: DiffLine[] = [];
const inss: DiffLine[] = [];
while (k < ops.length && ops[k].op !== "equal") {
const o = ops[k];
if (o.op === "del") dels.push({ op: "del", text: rawA[o.ai] });
else inss.push({ op: "ins", text: rawB[o.bi] });
k += 1;
}
const type: BlockType =
dels.length > 0 && inss.length > 0 ? "replace" : dels.length > 0 ? "delete" : "insert";
blocks.push({ type, lines: [...dels, ...inss] });
}
return blocks;
}
export type FoldedRow =
| { kind: "line"; op: LineOp; text: string; segments?: InlineSegment[] }
| { kind: "fold"; count: number };
/**
* 上下文折叠:超过 context*2+2 行的 equal 块只保留变更两侧各 context 行,
* 头/尾 equal 块只保留单侧;返回渲染用的行序列(fold 为折叠标记)。
*/
export function toFoldedRows(blocks: DiffBlock[], context = 3): FoldedRow[] {
const rows: FoldedRow[] = [];
const pushLine = (l: DiffLine) =>
rows.push({ kind: "line", op: l.op, text: l.text, segments: l.segments });
blocks.forEach((b, bi) => {
if (!(b.type === "equal" && b.lines.length > context * 2 + 2)) {
b.lines.forEach(pushLine);
return;
}
const isHead = bi === 0;
const isTail = bi === blocks.length - 1;
if (isHead && isTail) {
// 整个 diff 都是相同内容:不折叠
b.lines.forEach(pushLine);
return;
}
const head = isHead ? 0 : context;
const tail = isTail ? 0 : context;
for (let i = 0; i < head; i++) pushLine(b.lines[i]);
rows.push({ kind: "fold", count: b.lines.length - head - tail });
for (let i = b.lines.length - tail; i < b.lines.length; i++) pushLine(b.lines[i]);
});
return rows;
}
/* ---------------- 第四层:行内细分(词级 diff) ---------------- */
// CJK 逐字成 token(中文无词边界),西文按单词,空白连续,其余单字符
const TOKEN_RE = /[\p{Script=Han}\p{Script=Hiragana}\p{Script=Katakana}\p{Script=Hangul}]|[A-Za-z0-9_]+|\s+|[^\s]/gu;
interface Tokens {
tokens: string[];
starts: number[];
ends: number[];
}
function tokenize(line: string): Tokens {
const tokens: string[] = [];
const starts: number[] = [];
const ends: number[] = [];
for (const m of line.matchAll(TOKEN_RE)) {
const start = m.index;
if (start === undefined) continue;
tokens.push(m[0]);
starts.push(start);
ends.push(start + m[0].length);
}
return { tokens, starts, ends };
}
function lcsTokenLen(a: string[], b: string[]): number {
const n = a.length;
const m = b.length;
const width = m + 1;
const dp = new Uint32Array((n + 1) * width);
for (let i = n - 1; i >= 0; i--) {
for (let j = m - 1; j >= 0; j--) {
dp[i * width + j] =
a[i] === b[j]
? dp[(i + 1) * width + (j + 1)] + 1
: Math.max(dp[(i + 1) * width + j], dp[i * width + (j + 1)]);
}
}
return dp[0];
}
/** X 视角下的变更片段:词级 LCS 中未被匹配的连续 token 合并为一个字符区间 */
function changedSegments(
t: Tokens,
ops: Array<{ op: "equal" | "chg"; idx: number }>,
type: "del" | "ins"
): InlineSegment[] {
const segs: InlineSegment[] = [];
let cur: InlineSegment | null = null;
for (const o of ops) {
if (o.op === "equal") {
cur = null;
continue;
}
const start = t.starts[o.idx];
const end = t.ends[o.idx];
if (cur && cur.end === start) {
cur.end = end;
} else {
cur = { start, end, type };
segs.push(cur);
}
}
return segs;
}
/** 词级 LCS 回溯,产出 X/Y 各自的 equal/chg 序列(idx 为各自 token 下标) */
function tokenOps(x: Tokens, y: Tokens): {
xOps: Array<{ op: "equal" | "chg"; idx: number }>;
yOps: Array<{ op: "equal" | "chg"; idx: number }>;
} {
const n = x.tokens.length;
const m = y.tokens.length;
const width = m + 1;
const dp = new Uint32Array((n + 1) * width);
for (let i = n - 1; i >= 0; i--) {
for (let j = m - 1; j >= 0; j--) {
dp[i * width + j] =
x.tokens[i] === y.tokens[j]
? dp[(i + 1) * width + (j + 1)] + 1
: Math.max(dp[(i + 1) * width + j], dp[i * width + (j + 1)]);
}
}
const xOps: Array<{ op: "equal" | "chg"; idx: number }> = [];
const yOps: Array<{ op: "equal" | "chg"; idx: number }> = [];
let i = 0;
let j = 0;
while (i < n && j < m) {
if (x.tokens[i] === y.tokens[j]) {
xOps.push({ op: "equal", idx: i });
yOps.push({ op: "equal", idx: j });
i += 1;
j += 1;
} else if (dp[(i + 1) * width + j] >= dp[i * width + (j + 1)]) {
xOps.push({ op: "chg", idx: i });
i += 1;
} else {
yOps.push({ op: "chg", idx: j });
j += 1;
}
}
while (i < n) {
xOps.push({ op: "chg", idx: i });
i += 1;
}
while (j < m) {
yOps.push({ op: "chg", idx: j });
j += 1;
}
return { xOps, yOps };
}
/** 对 replace 块内按下标配对的行对做词级细分;相似度不足则整行变更、不产出 segments */
function annotateInline(blocks: DiffBlock[], inlineThreshold: number): void {
for (const b of blocks) {
if (b.type !== "replace") continue;
const dels = b.lines.filter((l) => l.op === "del");
const inss = b.lines.filter((l) => l.op === "ins");
const n = Math.min(dels.length, inss.length);
for (let i = 0; i < n; i++) {
const delLine = dels[i];
const insLine = inss[i];
if (delLine.text.length + insLine.text.length > MAX_INLINE_CHARS) continue;
const x = tokenize(delLine.text);
const y = tokenize(insLine.text);
if (x.tokens.length === 0 || y.tokens.length === 0) continue;
if (x.tokens.length * y.tokens.length > MAX_INLINE_CELLS) continue;
const ratio = (2 * lcsTokenLen(x.tokens, y.tokens)) / (x.tokens.length + y.tokens.length);
if (!(ratio > inlineThreshold)) continue;
const { xOps, yOps } = tokenOps(x, y);
const delSegs = changedSegments(x, xOps, "del");
const insSegs = changedSegments(y, yOps, "ins");
if (delSegs.length > 0) delLine.segments = delSegs;
if (insSegs.length > 0) insLine.segments = insSegs;
}
}
}
/* ---------------- 入口 ---------------- */
export function smartDiff(
oldText: string,
newText: string,
options: SmartDiffOptions = {}
): DiffResult {
const replaceThreshold = options.replaceThreshold ?? 0.2;
const inlineThreshold = options.inlineThreshold ?? 0.6;
const a = splitLines(oldText);
const b = splitLines(newText);
const ops: RawOp[] = [];
let wholeReplace = false;
if (a.cmp.length === 0 && b.cmp.length === 0) {
// 两侧皆空:无块
} else if (a.cmp.length === 0 || b.cmp.length === 0) {
// 单侧为空:整体删除/新增
if (a.cmp.length > 0) {
for (let i = 0; i < a.cmp.length; i++) ops.push({ op: "del", ai: i, bi: 0 });
} else {
for (let j = 0; j < b.cmp.length; j++) ops.push({ op: "ins", ai: 0, bi: j });
}
} else if (
a.cmp.length >= 2 &&
b.cmp.length >= 2 &&
lineSimilarity(a.cmp, b.cmp) < replaceThreshold
) {
// 整段替换:跳过逐行对齐,输出一个大删除块 + 一个大新增块
wholeReplace = true;
for (let i = 0; i < a.cmp.length; i++) ops.push({ op: "del", ai: i, bi: 0 });
for (let j = 0; j < b.cmp.length; j++) ops.push({ op: "ins", ai: 0, bi: j });
} else {
patienceDiff(a.cmp, b.cmp, 0, a.cmp.length, 0, b.cmp.length, ops, 0);
}
const blocks = buildBlocks(ops, a.raw, b.raw);
if (wholeReplace) {
// 相似度低于阈值判定为整段替换:唯一变更块标记为 block-replace,
// 不做行内细分(两侧内容无对应关系,细对齐只会产出噪音)
const blk = blocks.find((x) => x.type === "replace");
if (blk) blk.type = "block-replace";
}
annotateInline(blocks, inlineThreshold);
let dels = 0;
let adds = 0;
for (const blk of blocks) {
for (const l of blk.lines) {
if (l.op === "del") dels += 1;
else if (l.op === "ins") adds += 1;
}
}
return { blocks, stats: { adds, dels } };
}