add support for breadcrumb navs

src/breadcrumb-nav.ts

@@ -0,0 +1,60 @@
+
+import { marked } from 'marked';
+import { ParsedAttributes, parse_attributes } from './attrs';
+import { MarkdownOptions } from './render';
+
+export interface BreadcrumbNavToken extends marked.Tokens.Generic {
+	text: string;
+	attrs: ParsedAttributes;
+	items: marked.Token[][];
+}
+
+export function breadcrumb_nav_ext(renderer: marked.Renderer, opts: MarkdownOptions) : marked.TokenizerExtension & marked.RendererExtension {
+	return {
+		name: 'breadcrumb_nav',
+		level: 'block',
+		start: (src) => src.match(/^\/\/\//)?.index,
+		tokenizer(src, tokens) {
+			const rule = /^\/\/\/(\/*)([^\n]+)?(?:\n)((?:[^\/]|\/\/?(?!\/\1))+)\/\/\/\1/;
+			const match = rule.exec(src);
+
+			if (match) {
+				const token: BreadcrumbNavToken = {
+					type: 'breadcrumb_nav',
+					raw: match[0],
+					text: match[3],
+					attrs: parse_attributes(match[2] || ''),
+					tokens: [ ],
+					items: [ ],
+				};
+
+				const lines = match[3].trim().split('\n');
+
+				for (const line of lines) {
+					const tokens = this.lexer.inlineTokens(line, [ ]);
+					token.tokens.push(...tokens);
+					token.items.push(tokens);
+				}
+
+				return token;
+			}
+		},
+		renderer(token: BreadcrumbNavToken) {
+			return `<nav aria-label="breadcrumbs" ${token.attrs.html_attrs.join(' ')}>\n`
+				+ `\t<ol>\n`
+				+ '\t\t'
+					+ token.items.map((tokens, index) =>{ 
+						let item = '<li>';
+
+						if (index) {
+							item += '<span class="separator" aria-hidden="true">/</span> ';
+						}
+
+						return item + this.parser.parseInline(tokens, renderer) + '</li>';
+					}).join('\n\t\t')
+				+ '\n'
+				+ `\t</ol>\n`
+				+ `</nav>`;
+		}
+	};
+}

src/render.ts

@@ -9,6 +9,7 @@ import { katex_block_ext, katex_inline_ext } from './katex';
 import { footnote_list_ext, footnote_ref_ext } from './footnotes';
 import { description_list_ext } from './description-list';
 import { resolve_async_bindings } from './async-steps';
+import { breadcrumb_nav_ext } from './breadcrumb-nav';
 
 export interface MarkdownOptions {
 	base_url?: string;
@@ -40,6 +41,7 @@ export async function render_markdown_to_html(markdown: string, options: Markdow
 			description_list_ext(marked_options.renderer, options),
 			section_ext(marked_options.renderer, options),
 			icon_ext(marked_options.renderer, options),
+			breadcrumb_nav_ext(marked_options.renderer, options),
 			...(options.extensions || [ ]).map((ext) => {
 				return ext(marked_options.renderer, options);
 			}),