mirror of
https://github.com/bendtherules/ask262.git
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331 lines
8.6 KiB
TypeScript
331 lines
8.6 KiB
TypeScript
import type * as cheerio from "cheerio";
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/**
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* List of block-level HTML elements that should have newlines added after them
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* to preserve document structure during text extraction.
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*/
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export const BLOCK_ELEMENTS = [
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"p",
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"div",
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"h1",
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"h2",
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"h3",
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"h4",
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"h5",
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"h6",
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"li",
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"td",
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"th",
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"pre",
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"blockquote",
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"section",
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"emu-clause",
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"emu-note",
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"emu-example",
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"emu-table",
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"figure",
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"figcaption",
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"ul",
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"ol",
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"dl",
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"dt",
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"dd",
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"emu-production",
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"emu-rhs",
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];
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export interface FormatConfig {
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codeBlocks: {
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block: string[];
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inline: string[];
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grammar: string[];
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};
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links: string[];
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lists: {
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ordered: string[];
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unordered: string[];
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};
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tables: string[];
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}
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export const DEFAULT_CONFIG: FormatConfig = {
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codeBlocks: {
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block: ["pre>code", "emu-eqn:not([class*='inline'])"],
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inline: ["var", "emu-val", "emu-const", "emu-eqn.inline", "code"],
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grammar: ["emu-grammar"],
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},
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links: ["emu-xref a"],
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lists: {
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ordered: ["ol"],
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unordered: ["ul"],
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},
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tables: ["table", "emu-table"],
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};
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export function convertLinksToMarkdown(
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$: cheerio.CheerioAPI,
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selector: string = "emu-xref a[href]",
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): void {
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$(selector).each((_, elem) => {
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const $a = $(elem);
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const href = $a.attr("href") ?? "";
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// Skip external links
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if (href.startsWith("http")) return;
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// Strip filename prefix: "abstract-operations.html#sec-tonumber" → "#sec-tonumber"
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const hash = href.includes("#") ? `#${href.split("#")[1]}` : href;
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const text = $a.text().trim();
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if (!text || !hash) return;
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$a.replaceWith($(`<span class="link-markdown">[${text}](${hash})</span>`));
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});
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}
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export function convertInlineCodeToMarkdown(
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$: cheerio.CheerioAPI,
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tags: string[],
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): void {
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for (const tag of tags) {
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$(tag).each((_, elem) => {
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// Skip <code> inside <pre> (handled by block converter)
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if (
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"name" in elem &&
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elem.name === "code" &&
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$(elem).parent("pre").length > 0
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)
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return;
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const text = $(elem).text().trim();
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if (!text) return;
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$(elem).replaceWith($(`<span class="inline-code">\`${text}\`</span>`));
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});
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}
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}
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function extractLanguage(codeClass: string | undefined): string {
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// "javascript hljs" → "javascript", "python hljs" → "python"
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if (!codeClass) return "";
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const match = codeClass.match(/^(\w+)/);
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return match?.[1] ?? "";
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}
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export function convertBlockCodeToMarkdown(
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$: cheerio.CheerioAPI,
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tags: string[],
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): void {
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const selectors = tags.join(", ");
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if (!selectors) return;
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$(selectors).each((_, elem) => {
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const $elem = $(elem);
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const lang = extractLanguage($elem.attr("class"));
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const text = $elem.text().trim();
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$elem.replaceWith(
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$(`<pre class="code-markdown">\`\`\`${lang}\n${text}\n\`\`\`</pre>`),
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);
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});
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}
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/**
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* Returns the markdown list item prefix based on list type and nesting depth.
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* Alternates markers to visually distinguish nesting levels:
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* - Ordered lists: `1.` at even depth, `A.` at odd depth
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* - Unordered lists: `-` at even depth, `*` at odd depth
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*
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* @param isOrdered - Whether the list is ordered (ol) or unordered (ul)
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* @param depth - Nesting depth (0 = top-level)
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* @param index - Zero-based item index within its list
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* @returns Prefix string like "1. ", "A. ", "- ", or "* "
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*/
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function getListItemPrefix(
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isOrdered: boolean,
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depth: number,
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index: number,
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): string {
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if (isOrdered) {
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return depth % 2 === 0
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? `${index + 1}. `
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: `${String.fromCharCode(65 + index)}. `;
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}
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return depth % 2 === 0 ? "- " : "* ";
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}
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function listToMarkdown(
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$: cheerio.CheerioAPI,
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elem: any,
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depth: number = 0,
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): string {
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const $elem = $(elem);
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const isOrdered = elem.name === "ol";
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const indent = " ".repeat(depth);
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const lines: string[] = [];
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$elem.children("li").each((i, li) => {
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const prefix = getListItemPrefix(isOrdered, depth, i);
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const $li = $(li);
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const nestedLists: string[] = [];
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// Recurse into nested lists first (depth-first)
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$li.children("ol, ul").each((_, nested) => {
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const nestedMarkdown = listToMarkdown($, nested, depth + 1);
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nestedLists.push(nestedMarkdown);
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$(nested).remove();
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});
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// Now get full text
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const itemText = $li.text().trim().replace(/\s+/g, " ");
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lines.push(`${indent}${prefix}${itemText}`);
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for (const nested of nestedLists) {
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lines.push(nested);
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}
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});
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return lines.join("\n");
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}
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export function convertListsToMarkdown(
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$: cheerio.CheerioAPI,
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ordered: string[] = ["ol"],
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unordered: string[] = ["ul"],
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): void {
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const selectors = [...ordered, ...unordered].join(", ");
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if (!selectors) return;
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// Process from outermost — recursion handles depth-first nesting
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$(selectors).each((_, elem) => {
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// Skip if already processed (parent already handled this)
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if ($(elem).hasClass("list-markdown") || $(elem).hasClass("list-processed"))
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return;
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const markdown = listToMarkdown($, elem, 0);
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$(elem).replaceWith($(`<pre class="list-markdown">\n${markdown}\n</pre>`));
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});
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}
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export function convertGrammarToMarkdown(
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$: cheerio.CheerioAPI,
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selector: string = "emu-grammar",
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): void {
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if (!selector) return;
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$(selector).each((_, grammar) => {
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const text = $(grammar).text().trim();
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$(grammar).replaceWith(
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$(`<pre class="code-markdown">\`\`\`bnf\n${text}\n\`\`\`</pre>`),
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);
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});
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}
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/**
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* Converts HTML tables to markdown table format.
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* This preserves table structure when extracting text from HTML.
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* Replaces the original table with a <pre> element containing the markdown.
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*
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* @param $ - Cheerio API instance
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*/
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export function convertTablesToMarkdown($: cheerio.CheerioAPI): void {
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$("table, emu-table").each((_, tableElem) => {
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const $table = $(tableElem);
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const rows: string[][] = [];
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// Extract header rows
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$table.find("thead tr").each((_, rowElem) => {
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const row: string[] = [];
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$(rowElem)
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.find("th, td")
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.each((_, cellElem) => {
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row.push($(cellElem).text().trim().replace(/\|/g, "\\|"));
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});
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if (row.length > 0) rows.push(row);
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});
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// Extract body rows
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$table.find("tbody tr, tr").each((_, rowElem) => {
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// Skip if already processed as header
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if ($(rowElem).parent("thead").length > 0) return;
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const row: string[] = [];
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$(rowElem)
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.find("td, th")
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.each((_, cellElem) => {
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row.push($(cellElem).text().trim().replace(/\|/g, "\\|"));
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});
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if (row.length > 0) rows.push(row);
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});
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if (rows.length === 0) return;
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// Determine max columns
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const maxCols = Math.max(...rows.map((r) => r.length));
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// Build markdown table
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const mdLines: string[] = [];
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// Header row
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if (rows.length > 0) {
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const header = rows[0].concat(Array(maxCols - rows[0].length).fill(""));
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mdLines.push("| " + header.join(" | ") + " |");
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}
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// Separator
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mdLines.push("|" + Array(maxCols).fill(" --- ").join("|") + "|");
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// Data rows (skip header if we have more rows)
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const dataRows = rows.length > 1 ? rows.slice(1) : [];
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for (const row of dataRows) {
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const padded = row.concat(Array(maxCols - row.length).fill(""));
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mdLines.push("| " + padded.join(" | ") + " |");
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}
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// Replace table with markdown
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const markdown = mdLines.join("\n");
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$table.replaceWith($(`<pre class="table-markdown">\n${markdown}\n</pre>`));
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});
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}
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/**
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* Adds newlines after specified block elements to preserve document structure.
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* This helps text splitters maintain paragraph/section boundaries.
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*
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* @param $ - Cheerio API instance
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* @param elements - Array of element tag names to add newlines after
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*/
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export function addNewlinesAfterBlocks(
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$: cheerio.CheerioAPI,
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elements: string[] = BLOCK_ELEMENTS,
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): void {
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for (const tag of elements) {
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$.root()
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.find(tag)
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.each((_, el) => {
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$(el).append("\n");
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});
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}
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}
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export function formatForIngestion(
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$: cheerio.CheerioAPI,
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config: Partial<FormatConfig> = {},
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): void {
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const cfg = { ...DEFAULT_CONFIG, ...config };
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// 1. Inject newlines globally (affects li, p, pre, emu-production, emu-rhs, etc.)
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addNewlinesAfterBlocks($);
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// 2. Inline leaves (links first — must be before lists/code destroy DOM)
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convertLinksToMarkdown($, cfg.links.join(", "));
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// 3. Inline code
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convertInlineCodeToMarkdown($, cfg.codeBlocks.inline);
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// 4. Block leaves (fenced code)
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convertBlockCodeToMarkdown($, cfg.codeBlocks.block);
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// 5. Structural parents (grammar, lists, tables)
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convertGrammarToMarkdown($, cfg.codeBlocks.grammar.join(", "));
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convertListsToMarkdown($, cfg.lists.ordered, cfg.lists.unordered);
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convertTablesToMarkdown($);
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}
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