work in progress

src/core/create_template.ts

@@ -0,0 +1,74 @@
+import * as fs from 'fs';
+import chalk from 'chalk';
+import framer from 'code-frame';
+import { locate } from 'locate-character';
+
+function error(e: any) {
+	if (e.title) console.error(chalk.bold.red(e.title));
+	if (e.body) console.error(chalk.red(e.body));
+	if (e.url) console.error(chalk.cyan(e.url));
+	if (e.frame) console.error(chalk.grey(e.frame));
+
+	process.exit(1);
+}
+
+export default function create_templates() {
+	const template = fs.readFileSync(`app/template.html`, 'utf-8');
+
+	const index = template.indexOf('%sapper.main%');
+	if (index !== -1) {
+		// TODO remove this in a future version
+		const { line, column } = locate(template, index, { offsetLine: 1 });
+		const frame = framer(template, line, column);
+
+		error({
+			title: `app/template.html`,
+			body: `<script src='%sapper.main%'> is unsupported — use %sapper.scripts% (without the <script> tag) instead`,
+			url: 'https://github.com/sveltejs/sapper/issues/86',
+			frame
+		});
+	}
+
+	return {
+		render: (data: Record<string, string>) => {
+			return template.replace(/%sapper\.(\w+)%/g, (match, key) => {
+				return key in data ? data[key] : '';
+			});
+		},
+		stream: (res: any, data: Record<string, string | Promise<string>>) => {
+			let i = 0;
+
+			function stream_inner(): Promise<void> {
+				if (i >= template.length) {
+					return;
+				}
+
+				const start = template.indexOf('%sapper', i);
+
+				if (start === -1) {
+					res.end(template.slice(i));
+					return;
+				}
+
+				res.write(template.slice(i, start));
+
+				const end = template.indexOf('%', start + 1);
+				if (end === -1) {
+					throw new Error(`Bad template`); // TODO validate ahead of time
+				}
+
+				const tag = template.slice(start + 1, end);
+				const match = /sapper\.(\w+)/.exec(tag);
+				if (!match || !(match[1] in data)) throw new Error(`Bad template`); // TODO ditto
+
+				return Promise.resolve(data[match[1]]).then(datamatch => {
+					res.write(datamatch);
+					i = end + 1;
+					return stream_inner();
+				});
+			}
+
+			return Promise.resolve().then(stream_inner);
+		}
+	};
+}