Add option to disable section label in html (#533)

book-example/src/format/config.md

@@ -84,6 +84,9 @@ The following configuration options are available:
   removing the current behaviour, you can specify a set of javascript files
   that will be loaded alongside the default one.
 - **playpen:** A subtable for configuring various playpen settings.
+- **no-section-label**: mdBook by defaults adds section label in table of
+  contents column. For example, "1.", "2.1". Set this option to true to
+  disable those labels. Defaults to `false`.
 
 **book.toml**
 ```toml

src/config.rs

@@ -326,6 +326,7 @@ pub struct HtmlConfig {
     /// This config item *should not be edited* by the end user.
     #[doc(hidden)]
     pub livereload_url: Option<String>,
+    pub no_section_label: bool,
 }
 
 /// Configuration for tweaking how the the HTML renderer handles the playpen.

src/renderer/html_handlebars/hbs_renderer.rs

@@ -239,8 +239,8 @@ impl HtmlHandlebars {
                     json!(utils::fs::path_to_root(Path::new("print.md"))));
     }
 
-    fn register_hbs_helpers(&self, handlebars: &mut Handlebars) {
+    fn register_hbs_helpers(&self, handlebars: &mut Handlebars, html_config: &HtmlConfig) {
-        handlebars.register_helper("toc", Box::new(helpers::toc::RenderToc));
+        handlebars.register_helper("toc", Box::new(helpers::toc::RenderToc {no_section_label: html_config.no_section_label}));
         handlebars.register_helper("previous", Box::new(helpers::navigation::previous));
         handlebars.register_helper("next", Box::new(helpers::navigation::next));
     }
@@ -307,7 +307,7 @@ impl Renderer for HtmlHandlebars {
         )?;
 
         debug!("[*]: Register handlebars helpers");
-        self.register_hbs_helpers(&mut handlebars);
+        self.register_hbs_helpers(&mut handlebars, &html_config);
 
         let mut data = make_data(&ctx.root, &book, &ctx.config, &html_config)?;
 

src/renderer/html_handlebars/helpers/toc.rs

@@ -7,7 +7,9 @@ use pulldown_cmark::{html, Event, Parser, Tag};
 
 // Handlebars helper to construct TOC
 #[derive(Clone, Copy)]
-pub struct RenderToc;
+pub struct RenderToc {
+    pub no_section_label: bool
+}
 
 impl HelperDef for RenderToc {
     fn call(&self, _h: &Helper, _: &Handlebars, rc: &mut RenderContext) -> Result<(), RenderError> {
@@ -91,12 +93,14 @@ impl HelperDef for RenderToc {
                 false
             };
 
+            if !self.no_section_label {
                 // Section does not necessarily exist
                 if let Some(section) = item.get("section") {
                     rc.writer.write_all(b"<strong>")?;
                     rc.writer.write_all(section.as_bytes())?;
                     rc.writer.write_all(b"</strong> ")?;
                 }
+            }
 
             if let Some(name) = item.get("name") {
                 // Render only inline code blocks