godoc: make 'Overview' section collapsable

This makes packages with lengthly package comments easier to browse.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5901055

doc/godocs.js

@@ -164,21 +164,26 @@ function getElementsByClassName(base, clazz) {
   return foundElements;
 }
 
-function godocs_bindExampleToggle(eg) {
-  var heading = getElementsByClassName(eg, "exampleHeading");
+function godocs_bindToggle(el) {
+  var button = getElementsByClassName(el, "toggleButton");
   var callback = function() {
-    if (eg.className == "example") {
-      eg.className = "exampleVisible";
+    if (el.className == "toggle") {
+      el.className = "toggleVisible";
     } else {
-      eg.className = "example";
+      el.className = "toggle";
     }
   };
-  for (var i = 0; i < heading.length; i++) {
-    bindEvent(heading[i], "click", callback);
+  for (var i = 0; i < button.length; i++) {
+    bindEvent(button[i], "click", callback);
   }
 }
-function godocs_bindExampleLink(l) {
-  var prefix = "example_";
+function godocs_bindToggles(className) {
+  var els = getElementsByClassName(document, className);
+  for (var i = 0; i < els.length; i++) {
+    godocs_bindToggle(els[i]);
+  }
+}
+function godocs_bindToggleLink(l, prefix) {
   bindEvent(l, "click", function() {
     var i = l.href.indexOf("#"+prefix);
     if (i < 0) {
@@ -186,24 +191,23 @@ function godocs_bindExampleLink(l) {
     }
     var id = prefix + l.href.slice(i+1+prefix.length);
     var eg = document.getElementById(id);
-    eg.className = "exampleVisible";
+    eg.className = "toggleVisible";
   });
 }
-function godocs_bindExamples() {
-  var examples = getElementsByClassName(document, "example");
-  for (var i = 0; i < examples.length; i++) {
-    godocs_bindExampleToggle(examples[i]);
-  }
-  var links = getElementsByClassName(document, "exampleLink");
+function godocs_bindToggleLinks(className, prefix) {
+  var links = getElementsByClassName(document, className);
   for (i = 0; i < links.length; i++) {
-    godocs_bindExampleLink(links[i]);
+    godocs_bindToggleLink(links[i], prefix);
   }
 }
 
 function godocs_onload() {
   godocs_bindSearchEvents();
   godocs_generateTOC();
-  godocs_bindExamples();
+  godocs_bindToggles("toggle");
+  godocs_bindToggles("toggleVisible");
+  godocs_bindToggleLinks("exampleLink", "example_");
+  godocs_bindToggleLinks("overviewLink", "");
 }
 
 bindEvent(window, 'load', godocs_onload);

doc/style.css

@@ -364,11 +364,11 @@ div#blog .read {
 	text-align: right;
 }
 
-.exampleHeading { cursor: pointer; }
-.example .collapsed { display: block; }
-.example .expanded { display: none; }
-.exampleVisible .collapsed { display: none; }
-.exampleVisible .expanded { display: block; }
+.toggleButton { cursor: pointer; }
+.toggle .collapsed { display: block; }
+.toggle .expanded { display: none; }
+.toggleVisible .collapsed { display: none; }
+.toggleVisible .expanded { display: block; }
 
 table.codetable { margin-left: auto; margin-right: auto; border-style: none; }
 hr { border-style: none; border-top: 1px solid black; }

lib/godoc/example.html

-<div id="example_{{.Name}}" class="example">
+<div id="example_{{.Name}}" class="toggle">
 	<div class="collapsed">
-		<p class="exampleHeading">▹ <span class="text">Example{{example_suffix .Name}}</span></p>
+		<p class="exampleHeading toggleButton">▹ <span class="text">Example{{example_suffix .Name}}</span></p>
 	</div>
 	<div class="expanded">
-		<p class="exampleHeading">▾ <span class="text">Example{{example_suffix .Name}}</span></p>
+		<p class="exampleHeading toggleButton">▾ <span class="text">Example{{example_suffix .Name}}</span></p>
 		{{with .Doc}}<p>{{html .}}</p>{{end}}
 		<p>Code:</p>
 		<pre class="code">{{.Code}}</pre>

lib/godoc/package.html

@@ -10,7 +10,7 @@
 			<dd><code>import "{{html .ImportPath}}"</code></dd>
 			</dl>
 			<dl>
-			<dd><a href="#overview">Overview</a></dd>
+			<dd><a href="#overview" class="overviewLink">Overview</a></dd>
 			<dd><a href="#index">Index</a></dd>
 			{{if $.Examples}}
 				<dd><a href="#examples">Examples</a></dd>
@@ -20,9 +20,16 @@
 			{{end}}
 			</dl>
 		</div>
-		<h2 id="overview">Overview</h2>
 		<!-- The package's Name is printed as title by the top-level template -->
+		<div id="overview" class="toggleVisible">
+			<div class="collapsed">
+				<h2 class="toggleButton" title="Click to show Overview section">Overview ▹</h2>
+			</div>
+			<div class="expanded">
+				<h2 class="toggleButton" title="Click to hide Overview section">Overview ▾</h2>
 				{{comment_html .Doc}}
+			</div>
+		</div>
 		{{example_html "" $.Examples $.FSet}}
 	
 		<h2 id="index">Index</h2>