feat(engines) barebone markdown example implementation for dependency avoidance
This commit is contained in:
Benjamin Wegener
208
src/Views/Markdown.js
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208
src/Views/Markdown.js
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import Placekeeper from '../Utils/Placekeeper.js';
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/**
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* symbolic markdown engine implementation for illustrational purposes
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* @note at this point its preferable to avoid dependencies for as long as possible
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* @class
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*/
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export default class MarkdownEngine {
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#internalCache = new Map();
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constructor() {}
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/**
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* Handles the specified file by loading its content, parsing sections and variables,
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* and caching the result.
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*
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* @param {string} filepath - The path of the file to handle.
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* @returns {Object} - An object with a `parse` method that can be used to parse the file.
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* @throws {Error} - If the file is not found.
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*/
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async handle(filepath) {
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const file = Bun.file(filepath);
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if (!(await file.exists())) throw new Error('file not found');
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if (!file) throw new Error('something went wrong');
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const rawContent = await file.text();
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let { metadata, content } = await this.extractFrontMatter(rawContent);
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content = this.toHtml(content);
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const { sections, variables } = Placekeeper.init(content);
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this.#internalCache.set(
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filepath,
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new Map([
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['content', content],
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['sections', sections],
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['variables', variables],
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['metadata', metadata],
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['mimeType', file.type || 'text/html'],
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['size', file.size],
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])
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);
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console.log(filepath, this.#internalCache.get(filepath));
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return {
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parse: (data = null, options = {}) =>
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this.parse(filepath, data, options),
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};
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}
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/**
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* Parses the specified identifier using the provided data and options.
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* @param {string} identifier - The identifier of the file to parse.
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* @param {Object} [data={}] - The data object to replace placeholders in the file content.
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* @param {Object} [options={}] - The options object.
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* @returns {Response} - The parsed response object.
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* @throws {Error} - If the file is not found.
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*/
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async parse(identifier, data = {}, options = {}) {
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if (!this.#internalCache.has(identifier)) {
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throw new Error('file not found');
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}
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const view = this.#internalCache.get(identifier);
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let parsed = Placekeeper.parse(
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view.get('content'),
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view.get('sections')
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);
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for (const [key, value] of Object.entries(data)) {
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parsed = parsed.replace(
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new RegExp(`{{${key}}}`, 'g'),
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value.toString()
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);
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}
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return new Response(view.get('content'), {
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...(options || {}),
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headers: {
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...(options.headers || {}),
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'Content-Type': 'text/html', //view.get('mimeType'),
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'Content-Length': view.get(),
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},
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});
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}
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async extractFrontMatter(content) {
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/**
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* Parses a value and returns the appropriate data type.
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* @param {string} value - The value to be parsed.
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* @returns {string|boolean|number|array} - The parsed value.
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*/
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function parseValue(value) {
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console.log(value);
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value = value.trim();
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if (value.startsWith('"') && value.endsWith('"'))
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return value.substring(1, value.length - 1);
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if (value === 'true' || value === 'false') return value === 'true';
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if (!isNaN(value)) return Number(value);
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if (value.startsWith('[') && value.endsWith(']'))
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return value
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.substring(1, value.length - 1)
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.split(',')
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.map((v) => parseValue(v.trim()));
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return value;
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}
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let lines = content.split('\n');
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let isFrontMatter = false;
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const variables = new Map();
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let idx = 0;
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while (lines.length > 0) {
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const line = lines.shift().toString().trim();
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if (
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line === '' || // ignore empty lines
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line.startsWith('#') // ignore comments
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) {
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idx++;
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continue;
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}
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if (line === '---') {
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if (isFrontMatter) break;
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isFrontMatter = true;
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idx++;
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continue;
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}
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if (isFrontMatter && line.indexOf(':') === -1) continue; // ignore invalid lines
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const key = line.substring(0, line.indexOf(':')).trim();
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let value = line.substring(line.indexOf(':') + 1).trim();
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if (value == '') {
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idx++;
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continue;
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}
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value = parseValue(value);
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variables.set(key, value);
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idx++;
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}
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return {
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metadata: variables,
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content: lines.join('\n'),
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};
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}
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/**
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* retrieves the content of a markdown file and returns it as html
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*/
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toHtml(content) {
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let html = '';
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let lines = content.split('\n');
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while (lines.length > 0) {
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const line = lines.shift().toString().trim();
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if (line === '') continue;
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if (line.startsWith('#')) {
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const level = line.indexOf(' ');
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html += `<h${level}>${line
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.substring(level)
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.trim()}</h${level}>`;
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} else {
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if (line.startsWith('- ') || line.startsWith('1.')) {
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const numerical = line.startsWith('1.');
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html += numerical ? '<ol>' : '<ul>';
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while (
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lines.length > 0 &&
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(lines[0].startsWith('-') ||
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lines[0].startsWith('\t') ||
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lines[0].startsWith('1.') ||
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lines[0].startsWith(' '.repeat(4)))
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) {
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const item = lines.shift().toString().trim();
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html += `<li>${item
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.substring(item.indexOf(' ') + 1)
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.trim()}</li>`;
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}
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html += numerical ? '</ol>' : '</ul>';
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} else if (line.startsWith('```')) {
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const lang = line.substring(3).trim();
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let code = '';
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while (lines.length > 0 && !lines[0].startsWith('```')) {
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code += lines.shift().toString().trim() + '\n';
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}
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let attr = '';
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if (lang) attr = ` class="language-${lang}"`;
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html += `<pre><code${attr}>${code}</code></pre>`;
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} else if (line.startsWith('---')) {
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html += '<div class="hr"><hr></div>';
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} else if (line.startsWith('> ')) {
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let item = line;
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html += '<blockquote>';
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while (lines.length > 0 && lines[0].startsWith('>')) {
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html += lines
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.shift()
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.toString()
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.trim()
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.substring(2)
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.trim();
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}
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html += '</blockquote>';
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} else {
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html += `<p>${line}</p>`;
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}
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}
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}
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return html;
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}
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}
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