go.tools/present: add Raw content to Code for new go-tour.

R=adg
CC=golang-dev
https://golang.org/cl/26390044

present/code.go

@@ -32,6 +32,7 @@ type Code struct {
 	Text template.HTML
 	Play bool   // runnable code
 	Ext  string // file extension
+	Raw  []byte // content of the file
 }
 
 func (c Code) TemplateName() string { return "code" }
@@ -130,6 +131,7 @@ func parseCode(ctx *Context, sourceFile string, sourceLine int, cmd string) (Ele
 		Text: template.HTML(buf.String()),
 		Play: play,
 		Ext:  filepath.Ext(filename),
+		Raw:  textBytes,
 	}, nil
 }
 

present/parse.go

@@ -41,6 +41,16 @@ func (d *Doc) Render(w io.Writer, t *template.Template) error {
 	return t.ExecuteTemplate(w, "root", data)
 }
 
+// Render renders the section to the given writer using the provided template.
+func (s *Section) Render(w io.Writer, t *template.Template) error {
+	data := struct {
+		*Section
+		Template    *template.Template
+		PlayEnabled bool
+	}{s, t, PlayEnabled}
+	return t.ExecuteTemplate(w, "section", data)
+}
+
 type ParseFunc func(ctx *Context, fileName string, lineNumber int, inputLine string) (Elem, error)
 
 // Register binds the named action, which does not begin with a period, to the