@diplodoc/transform/lib/frontmatter.js

A simple transformer of text in YFM (Yandex Flavored Markdown) to HTML

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.composeFrontMatter = exports.extractFrontMatter = void 0;
const js_yaml_1 = require("js-yaml");
const ts_dedent_1 = require("ts-dedent");
const cloneDeepWith_1 = __importDefault(require("lodash/cloneDeepWith"));
const log_1 = require("./log");
const SEP = '---';
/**
 * Temporary workaround to enable parsing YAML metadata from potentially
 * Liquid-aware source files
 * @param content Input string which could contain Liquid-style substitution syntax (which clashes with YAML
 * object syntax)
 * @returns String with `{}` escaped, ready to be parsed with `js-yaml`
 */
const escapeLiquid = (content) => content.replace(/{{/g, '(({{').replace(/}}/g, '}}))');
/**
 * Inverse of a workaround defined above.
 * @see `escapeLiquid`
 * @param escapedContent Input string with `{}` escaped with backslashes
 * @returns Unescaped string
 */
const unescapeLiquid = (escapedContent) => escapedContent.replace(/\(\({{/g, '{{').replace(/}}\)\)/g, '}}');
const matchMetadata = (fileContent) => {
    if (!fileContent.startsWith(SEP)) {
        return null;
    }
    const closeStart = fileContent.indexOf('\n' + SEP, SEP.length);
    const closeEnd = fileContent.indexOf('\n', closeStart + 1);
    if (closeStart === -1) {
        return null;
    }
    return [fileContent.slice(SEP.length, closeStart).trim(), fileContent.slice(closeEnd + 1)];
};
const duplicateKeysCompatibleLoad = (yaml, filePath) => {
    try {
        return (0, js_yaml_1.load)(yaml);
    }
    catch (e) {
        if (e instanceof js_yaml_1.YAMLException) {
            const duplicateKeysDeprecationWarning = (0, ts_dedent_1.dedent) `
                In ${filePath !== null && filePath !== void 0 ? filePath : '(unknown)'}: Encountered a YAML parsing exception when processing file metadata: ${e.reason}.
                It's highly possible the input file contains duplicate mapping keys.
                Will retry processing with necessary compatibility flags.
                Please note that this behaviour is DEPRECATED and WILL be removed in a future version
                without further notice, so the build WILL fail when supplied with YAML-incompatible meta.
            `;
            log_1.log.warn(duplicateKeysDeprecationWarning);
            return (0, js_yaml_1.load)(yaml, { json: true });
        }
        throw e;
    }
};
const extractFrontMatter = (fileContent, filePath) => {
    const matches = matchMetadata(fileContent);
    if (matches) {
        const [metadata, strippedContent] = matches;
        return [
            (0, cloneDeepWith_1.default)(duplicateKeysCompatibleLoad(escapeLiquid(metadata), filePath), (v) => (typeof v === 'string' ? unescapeLiquid(v) : undefined)),
            strippedContent,
        ];
    }
    return [{}, fileContent];
};
exports.extractFrontMatter = extractFrontMatter;
const composeFrontMatter = (frontMatter, strippedContent) => {
    const dumped = (0, js_yaml_1.dump)(frontMatter, { lineWidth: -1 }).trim();
    // This empty object check is a bit naive
    // The other option would be to check if all own fields are `undefined`,
    // since we exploit passing in `undefined` to remove a field quite a bit
    if (dumped === '{}') {
        return strippedContent;
    }
    return `${SEP}\n${dumped}\n${SEP}\n${strippedContent}`;
};
exports.composeFrontMatter = composeFrontMatter;
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