stream responses - fixes #19

lib/templates.js

@@ -26,10 +26,36 @@ function create_templates() {
 			return {
 				test: status => pattern.test(status),
 				specificity,
-				render(data) {
+				render: data => {
 					return template.replace(/%sapper\.(\w+)%/g, (match, key) => {
 						return key in data ? data[key] : '';
 					});
+				},
+				stream: async (res, data) => {
+					let i = 0;
+
+					do {
+						const start = template.indexOf('%sapper', i);
+
+						if (start === -1) {
+							res.end(template.slice(start));
+							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
+
+						res.write(await data[match[1]]);
+						i = end + 1;
+					} while (i < template.length);
 				}
 			}
 		})
@@ -52,5 +78,12 @@ exports.render = (status, data) => {
 	const template = templates.find(template => template.test(status));
 	if (template) return template.render(data);
 
+	return `Missing template for status code ${status}`;
+};
+
+exports.stream = (res, status, data) => {
+	const template = templates.find(template => template.test(status));
+	if (template) return template.stream(res, data);
+
 	return `Missing template for status code ${status}`;
 };