From 3c61655e93ac12455ffd162c3d14169e7eadd5fd Mon Sep 17 00:00:00 2001
From: Alan Palazzolo <alan.palazzolo@startribune.com>
Date: Tue, 20 Mar 2018 13:45:47 -0500
Subject: [PATCH] Add option preserve comments in SSR rendering.

---
 README.md                                     |  1 +
 .../server-side-rendering/visitors/Comment.ts | 11 +++-
 src/interfaces.ts                             |  4 ++
 .../samples/ssr-preserve-comments/_config.js  |  6 ++
 .../ssr-preserve-comments/expected-bundle.js  | 59 ++++++++++++++++++
 .../samples/ssr-preserve-comments/expected.js | 62 +++++++++++++++++++
 .../samples/ssr-preserve-comments/input.html  |  3 +
 7 files changed, 144 insertions(+), 2 deletions(-)
 create mode 100644 test/js/samples/ssr-preserve-comments/_config.js
 create mode 100644 test/js/samples/ssr-preserve-comments/expected-bundle.js
 create mode 100644 test/js/samples/ssr-preserve-comments/expected.js
 create mode 100644 test/js/samples/ssr-preserve-comments/input.html

diff --git a/README.md b/README.md
index 95b352e16a..6a9c5455f5 100644
--- a/README.md
+++ b/README.md
@@ -93,6 +93,7 @@ The Svelte compiler optionally takes a second argument, an object of configurati
 | `filename` | `string` | The filename to use in sourcemaps and compiler error and warning messages. | `'SvelteComponent.html'` |
 | `amd`.`id` | `string` | The AMD module ID to use for the `'amd'` and `'umd'` output formats. | `undefined` |
 | `globals` | `object`, `function` | When outputting to the `'umd'`, `'iife'` or `'eval'` formats, an object or function mapping the names of imported dependencies to the names of global variables. | `{}` |
+| `preserveComments` | `boolean` | Include comments in rendering.  Currently, only applies to SSR rendering | `false` |
 | | | |
 | `onerror` | `function` | Specify a callback for when Svelte encounters an error while compiling the component. Passed two arguments: the error object, and another function that is Svelte's default onerror handling. | (exception is thrown) |
 | `onwarn` | `function` | Specify a callback for when Svelte encounters a non-fatal warning while compiling the component. Passed two arguments: the warning object, and another function that is Svelte's default onwarn handling. | (warning is logged to console) |
diff --git a/src/generators/server-side-rendering/visitors/Comment.ts b/src/generators/server-side-rendering/visitors/Comment.ts
index ad10d20aa5..84d5c0fa7f 100644
--- a/src/generators/server-side-rendering/visitors/Comment.ts
+++ b/src/generators/server-side-rendering/visitors/Comment.ts
@@ -1,3 +1,10 @@
-export default function visitComment() {
-	// do nothing
+export default function visitComment(
+	generator: SsrGenerator,
+	block: Block,
+	node: Node
+) {
+	// Allow option to preserve comments, otherwise ignore
+	if (generator && generator.options && generator.options.preserveComments) {
+		generator.append(`<!--${node.data}-->`);
+	}
 }
diff --git a/src/interfaces.ts b/src/interfaces.ts
index de187da71d..36c0ff2863 100644
--- a/src/interfaces.ts
+++ b/src/interfaces.ts
@@ -62,6 +62,10 @@ export interface CompileOptions {
 	css?: boolean;
 	store?: boolean;
 
+	ssr?: {
+		preserveComments?: boolean | false;
+	};
+
 	onerror?: (error: Error) => void;
 	onwarn?: (warning: Warning) => void;
 }
diff --git a/test/js/samples/ssr-preserve-comments/_config.js b/test/js/samples/ssr-preserve-comments/_config.js
new file mode 100644
index 0000000000..9e62c8d192
--- /dev/null
+++ b/test/js/samples/ssr-preserve-comments/_config.js
@@ -0,0 +1,6 @@
+export default {
+	options: {
+		generate: 'ssr',
+		preserveComments: true
+	}
+};
diff --git a/test/js/samples/ssr-preserve-comments/expected-bundle.js b/test/js/samples/ssr-preserve-comments/expected-bundle.js
new file mode 100644
index 0000000000..19461df020
--- /dev/null
+++ b/test/js/samples/ssr-preserve-comments/expected-bundle.js
@@ -0,0 +1,59 @@
+var SvelteComponent = {};
+SvelteComponent.data = function() {
+	return {};
+};
+
+SvelteComponent.render = function(state, options = {}) {
+	var components = new Set();
+
+	function addComponent(component) {
+		components.add(component);
+	}
+
+	var result = { head: '', addComponent };
+	var html = SvelteComponent._render(result, state, options);
+
+	var cssCode = Array.from(components).map(c => c.css && c.css.code).filter(Boolean).join('\n');
+
+	return {
+		html,
+		head: result.head,
+		css: { code: cssCode, map: null },
+		toString() {
+			return html;
+		}
+	};
+};
+
+SvelteComponent._render = function(__result, state, options) {
+	__result.addComponent(SvelteComponent);
+
+	state = Object.assign({}, state);
+
+	return `<div>content</div>
+<!-- comment -->
+<div>more content</div>`;
+};
+
+SvelteComponent.css = {
+	code: '',
+	map: null
+};
+
+var warned = false;
+SvelteComponent.renderCss = function() {
+	if (!warned) {
+		console.error('Component.renderCss(...) is deprecated and will be removed in v2 — use Component.render(...).css instead');
+		warned = true;
+	}
+
+	var components = [];
+
+	return {
+		css: components.map(x => x.css).join('\n'),
+		map: null,
+		components
+	};
+};
+
+module.exports = SvelteComponent;
diff --git a/test/js/samples/ssr-preserve-comments/expected.js b/test/js/samples/ssr-preserve-comments/expected.js
new file mode 100644
index 0000000000..eff9344154
--- /dev/null
+++ b/test/js/samples/ssr-preserve-comments/expected.js
@@ -0,0 +1,62 @@
+"use strict";
+
+var SvelteComponent = {};;
+
+SvelteComponent.data = function() {
+	return {};
+};
+
+SvelteComponent.render = function(state, options = {}) {
+	var components = new Set();
+
+	function addComponent(component) {
+		components.add(component);
+	}
+
+	var result = { head: '', addComponent };
+	var html = SvelteComponent._render(result, state, options);
+
+	var cssCode = Array.from(components).map(c => c.css && c.css.code).filter(Boolean).join('\n');
+
+	return {
+		html,
+		head: result.head,
+		css: { code: cssCode, map: null },
+		toString() {
+			return html;
+		}
+	};
+}
+
+SvelteComponent._render = function(__result, state, options) {
+	__result.addComponent(SvelteComponent);
+
+	state = Object.assign({}, state);
+
+	return `<div>content</div>
+<!-- comment -->
+<div>more content</div>`;
+};
+
+SvelteComponent.css = {
+	code: '',
+	map: null
+};
+
+var warned = false;
+SvelteComponent.renderCss = function() {
+	if (!warned) {
+		console.error('Component.renderCss(...) is deprecated and will be removed in v2 — use Component.render(...).css instead');
+		warned = true;
+	}
+
+	var components = [];
+
+	return {
+		css: components.map(x => x.css).join('\n'),
+		map: null,
+		components
+	};
+};
+
+module.exports = SvelteComponent;
diff --git a/test/js/samples/ssr-preserve-comments/input.html b/test/js/samples/ssr-preserve-comments/input.html
new file mode 100644
index 0000000000..7f7e291caa
--- /dev/null
+++ b/test/js/samples/ssr-preserve-comments/input.html
@@ -0,0 +1,3 @@
+<div>content</div>
+<!-- comment -->
+<div>more content</div>