Add support for EXCLUDE_TAGS and :noexport:

org/document.go

@@ -80,7 +80,8 @@ func NewDocument() *Document {
 		MaxEmphasisNewLines: 1,
 		BufferSettings:      map[string]string{},
 		DefaultSettings: map[string]string{
-			"TODO": "TODO | DONE",
+			"TODO":         "TODO | DONE",
+			"EXCLUDE_TAGS": "noexport",
 		},
 		Log: log.New(os.Stderr, "go-org: ", 0),
 	}

org/html.go

@@ -16,6 +16,7 @@ type HTMLWriter struct {
 	HighlightCodeBlock    func(source, lang string) string
 	FootnotesHeadingTitle string
 	htmlEscape            bool
+	excludeTags           []string
 	log                   *log.Logger
 }
 
@@ -65,6 +66,7 @@ func (w *HTMLWriter) nodesAsString(nodes ...Node) string {
 }
 
 func (w *HTMLWriter) before(d *Document) {
+	w.excludeTags = strings.Fields(d.Get("EXCLUDE_TAGS"))
 	w.log = d.Log
 }
 
@@ -207,6 +209,13 @@ func (w *HTMLWriter) writeHeadline(h Headline) {
 	if h.Lvl == 1 && title == w.FootnotesHeadingTitle {
 		return
 	}
+	for _, excludeTag := range w.excludeTags {
+		for _, tag := range h.Tags {
+			if excludeTag == tag {
+				return
+			}
+		}
+	}
 
 	if id, ok := h.Properties.Get("CUSTOM_ID"); ok {
 		w.WriteString(fmt.Sprintf(`<h%d id="%s">`, h.Lvl, id) + "\n")

org/testdata/headlines.html

@@ -55,5 +55,6 @@ it&#39;s possible to use <code class="verbatim">#+SETUPFILE</code> - in this cas
 <div class="highlight">
 <pre>
 #+TODO: TODO DONE CUSTOM
+#+EXCLUDE_TAGS: noexport custom_noexport
 </pre>
 </div>

org/testdata/headlines.org

@@ -23,3 +23,7 @@ Still outside the drawer
 it's possible to use =#+SETUPFILE= - in this case the setup file contains the following
 
 #+INCLUDE: "setup_file_org" src org
+* excluded headline                                                :custom_noexport:
+this headline and it's content are not exported as it is marked with an =EXCLUDE_TAGS= tag.
+By default =EXCLUDE_TAGS= is just =:noexport:=.
+

org/testdata/headlines.pretty_org

@@ -23,3 +23,7 @@ Still outside the drawer
 it's possible to use =#+SETUPFILE= - in this case the setup file contains the following
 
 #+INCLUDE: "setup_file_org" src org
+* excluded headline                                         :custom_noexport:
+this headline and it's content are not exported as it is marked with an =EXCLUDE_TAGS= tag.
+By default =EXCLUDE_TAGS= is just =:noexport:=.
+

org/testdata/misc.html

@@ -68,6 +68,9 @@ Still outside the drawer
 it's possible to use =#+SETUPFILE= - in this case the setup file contains the following
 
 #+INCLUDE: "setup_file_org" src org
+* excluded headline                                                :custom_noexport:
+this headline and it's content are not exported as it is marked with an =EXCLUDE_TAGS= tag.
+By default =EXCLUDE_TAGS= is just =:noexport:=.
 </pre>
 </div>
 </li>

org/testdata/setup_file_org

@@ -1 +1,2 @@
 #+TODO: TODO DONE CUSTOM
+#+EXCLUDE_TAGS: noexport custom_noexport