godoc: support for package examples, display example suffixes

Fixes #2896.

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/5677047

lib/godoc/example.html

 <div id="example_{{.Name}}" class="example">
 	<div class="collapsed">
-		<p class="exampleHeading">▹ Example</p>
+		<p class="exampleHeading">▹ Example{{example_suffix .Name}}</p>
 	</div>
 	<div class="expanded">
-		<p class="exampleHeading">▾ Example</p>
+		<p class="exampleHeading">▾ Example{{example_suffix .Name}}</p>
 		<p>Code:</p>
 		<pre class="code">{{.Code}}</pre>
 		{{if .Output}}

lib/godoc/package.html

@@ -20,6 +20,7 @@
 		<h2 id="overview">Overview</h2>
 		<!-- The package's Name is printed as title by the top-level template -->
 		{{comment_html .Doc}}
+		{{example_html "" $.Examples $.FSet}}
 	
 		<h2 id="index">Index</h2>
 		<!-- Table of contents for API; must be named manual-nav to turn off auto nav. -->
@@ -56,7 +57,7 @@
 			<h4>Examples</h4>
 			<dl>
 			{{range $.Examples}}
-			<dd><a class="exampleLink" href="#example_{{.Name}}">{{.Name}}</a></dd>
+			<dd><a class="exampleLink" href="#example_{{.Name}}">{{example_name .Name}}</a></dd>
 			{{end}}
 			</dl>
 		{{end}}

src/cmd/godoc/godoc.go

@@ -526,7 +526,7 @@ func example_htmlFunc(funcName string, examples []*doc.Example, fset *token.File
 
 		err := exampleHTML.Execute(&buf, struct {
 			Name, Code, Output string
-		}{name, code, eg.Output})
+		}{eg.Name, code, eg.Output})
 		if err != nil {
 			log.Print(err)
 		}
@@ -534,6 +534,38 @@ func example_htmlFunc(funcName string, examples []*doc.Example, fset *token.File
 	return buf.String()
 }
 
+// example_nameFunc takes an example function name and returns its display
+// name. For example, "Foo_Bar_quux" becomes "Foo.Bar (Quux)".
+func example_nameFunc(s string) string {
+	name, suffix := splitExampleName(s)
+	// replace _ with . for method names
+	name = strings.Replace(name, "_", ".", 1)
+	// use "Package" if no name provided
+	if name == "" {
+		name = "Package"
+	}
+	return name + suffix
+}
+
+// example_suffixFunc takes an example function name and returns its suffix in
+// parenthesized form. For example, "Foo_Bar_quux" becomes " (Quux)".
+func example_suffixFunc(name string) string {
+	_, suffix := splitExampleName(name)
+	return suffix
+
+}
+
+func splitExampleName(s string) (name, suffix string) {
+	i := strings.LastIndex(s, "_")
+	if 0 <= i && i < len(s)-1 && !startsWithUppercase(s[i+1:]) {
+		name = s[:i]
+		suffix = " (" + strings.Title(s[i+1:]) + ")"
+		return
+	}
+	name = s
+	return
+}
+
 func pkgLinkFunc(path string) string {
 	relpath := relativeURL(path)
 	// because of the irregular mapping under goroot
@@ -610,7 +642,9 @@ var fmap = template.FuncMap{
 	"posLink_url": posLink_urlFunc,
 
 	// formatting of Examples
-	"example_html": example_htmlFunc,
+	"example_html":   example_htmlFunc,
+	"example_name":   example_nameFunc,
+	"example_suffix": example_suffixFunc,
 }
 
 func readTemplate(name string) *template.Template {

src/pkg/container/heap/example_test.go

@@ -58,10 +58,7 @@ func (pq *PriorityQueue) Pop() interface{} {
 }
 
 // 99:seven 88:five 77:zero 66:nine 55:three 44:two 33:six 22:one 11:four 00:eight
-func ExampleInterface() {
-	// The full code of this example, including the methods that implement
-	// heap.Interface, is in the file src/pkg/container/heap/example_test.go.
-
+func Example() {
 	const nItem = 10
 	// Random priorities for the items (a permutation of 0..9, times 11)).
 	priorities := [nItem]int{