332 lines
10 KiB
JavaScript
332 lines
10 KiB
JavaScript
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/**
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* 极简 YAML front matter 子集：解析 + 序列化（零依赖）。
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*
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* 为什么不用 gray-matter / js-yaml：
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* 这个后端只服务「编辑自己的 Hugo 文章」这一件事，语料是固定的 100 多篇
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* Markdown。为此拖进一棵依赖树不值得，镜像也能小一圈。
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*
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* 覆盖的形态（Hugo front matter 实际会用到的全部）：
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* key: 标量 key: '单引号' key: "双引号"
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* key: 123 / true key: [a, b] key: []
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* key: （空值 → null）
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* - a
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* - b （列表，缩进两格）
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* key: | / |- / |+ / > / >- / >+ （块标量）
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* key:
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* sub: 1 （一层嵌套 map，Hugo 的 params 会用到）
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*
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* 遇到覆盖不到的结构一律 **抛错**，由调用方降级为「原文照存」——
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* 宁可少解析，绝不猜错后把用户文章写坏。
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*/
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const OPEN = /^---[ \t]*\n/;
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/**
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* 把整篇文本切成 front matter 原文 / 正文 / 原文件换行风格。
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*
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* ★ 换行符必须原样保留：仓库 `.gitattributes` 是 `* text=auto`，
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* 仓库里存的是 LF，但 Windows 工作区检出是 CRLF。如果写回时统一成 LF，
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* 在 Windows 侧就会产生「整文件换行变更」的巨型 diff。所以这里记住原风格，
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* 交给 joinFrontMatter 还原。
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*
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* body **保留**它前面的空行，这样 join 出来的结果与原文件逐字节相同。
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*/
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export function splitFrontMatter(text) {
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const eol = text.includes('\r\n') ? '\r\n' : '\n';
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const norm = text.replace(/\r\n/g, '\n');
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const open = OPEN.exec(norm);
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if (!open) return { raw: null, body: norm, eol };
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const rest = norm.slice(open[0].length);
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const lines = rest.split('\n');
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for (let i = 0; i < lines.length; i++) {
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if (lines[i].trim() === '---') {
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return {
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raw: lines.slice(0, i).join('\n'),
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body: lines.slice(i + 1).join('\n'),
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eol,
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};
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}
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}
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return { raw: null, body: norm, eol };
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}
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/** 组装回整篇文本（raw 为 null 表示本来就没有 front matter） */
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export function joinFrontMatter(raw, body, eol = '\n') {
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const s = raw == null ? body : '---\n' + raw.replace(/[ \t]+$/, '') + '\n---\n' + body;
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return eol === '\n' ? s : s.replace(/\n/g, eol);
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}
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// ---------------------------------------------------------------- 解析
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export function parse(raw) {
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const lines = raw.split('\n');
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const out = {};
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let i = 0;
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while (i < lines.length) {
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const line = lines[i];
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if (line.trim() === '' || line.trimStart().startsWith('#')) {
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i++;
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continue;
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}
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if (/^[ \t]/.test(line)) {
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throw new Error('顶层出现意外缩进: ' + JSON.stringify(line));
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}
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const m = /^([^:\s][^:]*):(.*)$/.exec(line);
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if (!m) throw new Error('无法解析的行: ' + JSON.stringify(line));
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const key = m[1].trim();
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const rest = m[2].trim();
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i++;
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// 空值：看后面有没有缩进块
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if (rest === '') {
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const block = [];
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while (i < lines.length && (lines[i].trim() === '' || /^[ \t]/.test(lines[i]))) {
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block.push(lines[i]);
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i++;
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}
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while (block.length && block[block.length - 1].trim() === '') block.pop();
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if (!block.length) {
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out[key] = null;
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} else if (/^-[ \t]?/.test(block[0].trimStart())) {
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out[key] = parseList(block);
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} else {
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out[key] = parseMap(block);
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}
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continue;
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}
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// 块标量
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if (/^[|>][+-]?$/.test(rest)) {
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const block = [];
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while (i < lines.length && (lines[i].trim() === '' || /^[ \t]/.test(lines[i]))) {
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block.push(lines[i]);
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i++;
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}
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out[key] = parseBlockScalar(block, rest);
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continue;
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}
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out[key] = parseScalar(rest);
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}
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return out;
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}
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function dedent(block) {
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let min = Infinity;
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for (const l of block) {
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if (l.trim() === '') continue;
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const n = l.match(/^[ \t]*/)[0].replace(/\t/g, ' ').length;
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if (n < min) min = n;
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}
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if (!isFinite(min)) min = 0;
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return block.map((l) => (l.trim() === '' ? '' : l.replace(/\t/g, ' ').slice(min)));
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}
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function parseBlockScalar(block, header) {
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const lines = dedent(block);
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while (lines.length && lines[lines.length - 1] === '') lines.pop();
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let text;
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if (header[0] === '|') {
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text = lines.join('\n');
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} else {
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// 折叠：单个换行变空格，空行保留为换行
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let acc = '';
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for (const l of lines) {
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if (l === '') {
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acc += '\n';
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continue;
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}
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if (acc !== '' && !acc.endsWith('\n')) acc += ' ';
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acc += l;
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}
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text = acc;
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}
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const chomp = header[1];
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if (chomp === '-') return text.replace(/\n+$/, '');
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if (chomp === '+') return text + '\n';
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return text.replace(/\n+$/, '') + '\n';
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}
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function parseList(block) {
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const lines = dedent(block);
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const out = [];
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for (let i = 0; i < lines.length; i++) {
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const l = lines[i];
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if (l.trim() === '') continue;
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const m = /^-[ \t]?(.*)$/.exec(l);
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if (!m) throw new Error('列表中出现了非列表项: ' + JSON.stringify(l));
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if (/^[ \t]/.test(l)) throw new Error('不支持多级列表');
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out.push(parseScalar(m[1]));
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}
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return out;
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}
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function parseMap(block) {
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const lines = dedent(block);
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const out = {};
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for (const l of lines) {
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if (l.trim() === '') continue;
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const m = /^([^:\s][^:]*):(.*)$/.exec(l);
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if (!m) throw new Error('嵌套 map 中出现无法解析的行: ' + JSON.stringify(l));
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out[m[1].trim()] = parseScalar(m[2].trim());
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}
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return out;
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}
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function parseScalar(s) {
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s = s.trim();
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if (s === '' || s === '~' || s === 'null') return null;
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if (s === 'true') return true;
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if (s === 'false') return false;
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if (/^'.*'$/.test(s)) return s.slice(1, -1).replace(/''/g, "'");
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if (/^".*"$/.test(s)) {
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try {
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return JSON.parse(s);
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} catch {
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// JSON.parse 不认 YAML 专属的 \Uxxxxxxxx（8 位）与 \xXX 转义 ——
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// 仓库里就有这种标题（Telegram bot 写入的 emoji，如 \U0001F605）。
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// 先把它们解成真实字符，再交给 JSON.parse 处理其余转义（\n、\" 等）。
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const pre = s
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.slice(1, -1)
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.replace(/\\U([0-9a-fA-F]{8})/g, (_, h) => String.fromCodePoint(parseInt(h, 16)))
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.replace(/\\x([0-9a-fA-F]{2})/g, (_, h) => String.fromCodePoint(parseInt(h, 16)));
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try {
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return JSON.parse('"' + pre + '"');
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} catch {
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return pre;
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}
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}
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}
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if (s.startsWith('[') && s.endsWith(']')) return parseInlineList(s);
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if (/^-?\d+$/.test(s)) return parseInt(s, 10);
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if (/^-?\d+\.\d+$/.test(s)) return parseFloat(s);
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return s;
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}
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function parseInlineList(s) {
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const inner = s.slice(1, -1).trim();
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if (!inner) return [];
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const out = [];
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let cur = '';
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let quote = null;
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for (const ch of inner) {
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if (quote) {
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cur += ch;
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if (ch === quote) quote = null;
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continue;
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}
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if (ch === "'" || ch === '"') {
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quote = ch;
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cur += ch;
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continue;
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}
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if (ch === ',') {
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out.push(parseScalar(cur));
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cur = '';
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continue;
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}
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cur += ch;
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}
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if (cur.trim() !== '') out.push(parseScalar(cur));
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return out;
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}
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// ---------------------------------------------------------------- 序列化
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const PLAIN_OK = /^[^\s\-?:,[\]{}#&*!|>'"%@`][^:#\n]*$/;
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function toYamlScalar(v) {
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if (v === null || v === undefined) return '';
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if (typeof v === 'boolean') return v ? 'true' : 'false';
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if (typeof v === 'number') return String(v);
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const s = String(v);
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if (s === '') return "''";
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// 这些形态不引起来会被 YAML 当成别的类型
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if (/^(true|false|null|~|yes|no|on|off)$/i.test(s)) return "'" + s + "'";
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if (/^-?\d+(\.\d+)?$/.test(s)) return s; // 纯数字：保持裸写，与现有语料一致
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if (s.includes('\n')) return null; // 交给调用方走块标量
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if (PLAIN_OK.test(s) && !s.startsWith(' ') && !s.endsWith(' ')) return s;
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return "'" + s.replace(/'/g, "''") + "'";
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}
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export function stringify(obj) {
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const out = [];
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for (const key of Object.keys(obj)) {
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const v = obj[key];
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if (v === null || v === undefined) {
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out.push(key + ':');
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continue;
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}
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if (Array.isArray(v)) {
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if (v.length === 0) {
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out.push(key + ': []');
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continue;
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}
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out.push(key + ':');
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for (const item of v) {
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const one = toYamlScalar(item);
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if (one === null) throw new Error('列表项不支持多行内容: ' + key);
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out.push(' - ' + one);
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}
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continue;
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}
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if (typeof v === 'object') {
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out.push(key + ':');
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for (const sub of Object.keys(v)) {
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const one = toYamlScalar(v[sub]);
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if (one === null) throw new Error('嵌套对象不支持多行内容: ' + key + '.' + sub);
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out.push(' ' + sub + ': ' + one);
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}
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continue;
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}
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if (typeof v === 'string' && v.includes('\n')) {
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// 块标量必须带上正确的 chomping 记号，否则值会变：
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// | clip —— 保留结尾的一个换行（YAML 默认，Hugo 语料里的 >- 折叠块就是这个）
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// |- strip —— 结尾不要换行
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// |+ keep —— 保留全部结尾换行
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// 漏了这一步，「值 = "xxx\n"」会被写成「值 = "xxx"」，是实打实的语义改动。
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const trailing = (/\n+$/.exec(v) || [''])[0].length;
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const header = trailing === 0 ? '|-' : trailing === 1 ? '|' : '|+';
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out.push(key + ': ' + header);
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for (const line of v.replace(/\n+$/, '').split('\n')) {
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out.push(' ' + line);
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}
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continue;
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}
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const one = toYamlScalar(v);
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if (one === null) throw new Error('无法序列化: ' + key);
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out.push(key + ': ' + one);
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}
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return out.join('\n');
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}
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/** 深比较：用来判断「用户到底动没动 front matter」 */
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export function deepEqual(a, b) {
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if (a === b) return true;
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if (a === null || b === null || typeof a !== 'object' || typeof b !== 'object') {
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return String(a) === String(b);
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}
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if (Array.isArray(a) !== Array.isArray(b)) return false;
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const ka = Object.keys(a);
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const kb = Object.keys(b);
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|
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if (ka.length !== kb.length) return false;
|
|||
|
|
for (const k of ka) {
|
|||
|
|
if (!Object.prototype.hasOwnProperty.call(b, k)) return false;
|
|||
|
|
if (!deepEqual(a[k], b[k])) return false;
|
|||
|
|
}
|
|||
|
|
return true;
|
|||
|
|
}
|