Experimental AsciiDoc support with external helpers

See gohugoio#470

 * Based on existing support for reStructuredText files

 * Handles content files with extensions `.asciidoc` and `.ad`

 * Pipes content through `asciidoctor --safe -`.
   If `asciidoctor` is not installed, then `asciidoc --safe -`.

 * To make sure `asciidoctor` or `asciidoc` is found, after adding
   a piece of AsciiDoc content, run `hugo` with the `-v` flag
   and look for this message:

        INFO: 2015/01/23 Rendering with /usr/bin/asciidoctor ...

Caveats:

 * The final "Last updated" timestamp is currently not stripped.

 * When `hugo` is run with `-v`, you may see a lot of these messages

        INFO: 2015/01/23 Rendering with /usr/bin/asciidoctor ...

   if you have lots of `*.ad`, `*.adoc` or `*.asciidoc` files.

 * Some versions of `asciidoc` may have trouble with its safe mode.
   To test if you are affected, try this:

        $ echo "Hello" | asciidoc --safe -
        asciidoc: ERROR: unsafe: ifeval invalid
        asciidoc: FAILED: ifeval invalid safe document

   If so, I recommend that you install `asciidoctor` instead.

Feedback and patches welcome!

Ideally, we should be using https://github.com/VonC/asciidocgo,
@VonC's wonderful Go implementation of Asciidoctor.  However,
there is still a bit of work needed for asciidocgo to expose
its API so that Hugo can actually use it.

Until then, hope this "experimental AsciiDoc support through external
helpers" can serve as a stopgap solution for our community. :-)

2015-01-30: Updated for the replaceShortcodeTokens() syntax change
2015-02-21: Add `.adoc` extension as suggested by @Fale

Conflicts:
	helpers/content.go

helpers/content.go

@@ -230,6 +230,8 @@ func RenderBytesWithTOC(ctx *RenderingContext) []byte {
 		return markdownRenderWithTOC(ctx)
 	case "markdown":
 		return markdownRenderWithTOC(ctx)
+	case "asciidoc":
+		return []byte(GetAsciidocContent(ctx.Content))
 	case "rst":
 		return []byte(GetRstContent(ctx.Content))
 	}
@@ -242,6 +244,8 @@ func RenderBytes(ctx *RenderingContext) []byte {
 		return markdownRender(ctx)
 	case "markdown":
 		return markdownRender(ctx)
+	case "asciidoc":
+		return []byte(GetAsciidocContent(ctx.Content))
 	case "rst":
 		return []byte(GetRstContent(ctx.Content))
 	}
@@ -299,6 +303,39 @@ func TruncateWordsToWholeSentence(words []string, max int) (string, bool) {
 	return strings.Join(words[:max], " "), true
 }
 
+// GetAsciidocContent calls asciidoctor or asciidoc as an external helper
+// to convert AsciiDoc content to HTML.
+func GetAsciidocContent(content []byte) string {
+	cleanContent := bytes.Replace(content, SummaryDivider, []byte(""), 1)
+
+	path, err := exec.LookPath("asciidoctor")
+	if err != nil {
+		path, err = exec.LookPath("asciidoc")
+		if err != nil {
+			jww.ERROR.Println("asciidoctor / asciidoc not found in $PATH: Please install.\n",
+				"                 Leaving AsciiDoc content unrendered.")
+			return (string(content))
+		}
+	}
+
+	jww.INFO.Println("Rendering with", path, "...")
+	cmd := exec.Command(path, "--safe", "-")
+	cmd.Stdin = bytes.NewReader(cleanContent)
+	var out bytes.Buffer
+	cmd.Stdout = &out
+	if err := cmd.Run(); err != nil {
+		jww.ERROR.Println(err)
+	}
+
+	asciidocLines := strings.Split(out.String(), "\n")
+	for i, line := range asciidocLines {
+		if strings.HasPrefix(line, "<body") {
+			asciidocLines = (asciidocLines[i+1 : len(asciidocLines)-3])
+		}
+	}
+	return strings.Join(asciidocLines, "\n")
+}
+
 // GetRstContent calls the Python script rst2html as an external helper
 // to convert reStructuredText content to HTML.
 func GetRstContent(content []byte) string {

helpers/general.go

@@ -63,6 +63,8 @@ func GuessType(in string) string {
 	switch strings.ToLower(in) {
 	case "md", "markdown", "mdown":
 		return "markdown"
+	case "asciidoc", "adoc", "ad":
+		return "asciidoc"
 	case "rst":
 		return "rst"
 	case "html", "htm":

helpers/general_test.go

@@ -15,6 +15,9 @@ func TestGuessType(t *testing.T) {
 		{"md", "markdown"},
 		{"markdown", "markdown"},
 		{"mdown", "markdown"},
+		{"asciidoc", "asciidoc"},
+		{"adoc", "asciidoc"},
+		{"ad", "asciidoc"},
 		{"rst", "rst"},
 		{"html", "html"},
 		{"htm", "html"},

hugolib/handler_page.go

@@ -95,7 +95,22 @@ func (h asciidocHandler) Extensions() []string { return []string{"asciidoc", "ad
 func (h asciidocHandler) PageConvert(p *Page, t tpl.Template) HandledResult {
 	p.ProcessShortcodes(t)
 
-	// TODO(spf13) Add Ascii Doc Logic here
+	// TODO(spf13) Add/Refactor AsciiDoc Logic here
+	tmpContent, tmpTableOfContents := helpers.ExtractTOC(p.renderContent(helpers.RemoveSummaryDivider(p.rawContent)))
+
+	if len(p.contentShortCodes) > 0 {
+		tmpContentWithTokensReplaced, err := replaceShortcodeTokens(tmpContent, shortcodePlaceholderPrefix, true, p.contentShortCodes)
+
+		if err != nil {
+			jww.FATAL.Printf("Fail to replace short code tokens in %s:\n%s", p.BaseFileName(), err.Error())
+			return HandledResult{err: err}
+		} else {
+			tmpContent = tmpContentWithTokensReplaced
+		}
+	}
+
+	p.Content = helpers.BytesToHTML(tmpContent)
+	p.TableOfContents = helpers.BytesToHTML(tmpTableOfContents)
 
 	//err := p.Convert()
 	return HandledResult{page: p, err: nil}