Add tag handler for collecting crate items from rustdoc output (#12903)

This PR adds a tag handler for collecting crate items from rustdoc's
HTML output.

This will serve as the foundation for getting more insight into a
crate's contents.

Release Notes:

- N/A

crates/assistant/src/slash_command/fetch_command.rs

@@ -1,3 +1,5 @@
+use std::cell::RefCell;
+use std::rc::Rc;
 use std::sync::atomic::AtomicBool;
 use std::sync::Arc;
 
@@ -5,7 +7,7 @@ use anyhow::{anyhow, bail, Context, Result};
 use assistant_slash_command::{SlashCommand, SlashCommandOutput, SlashCommandOutputSection};
 use futures::AsyncReadExt;
 use gpui::{AppContext, Task, WeakView};
-use html_to_markdown::{convert_html_to_markdown, markdown, HandleTag};
+use html_to_markdown::{convert_html_to_markdown, markdown, TagHandler};
 use http::{AsyncBody, HttpClient, HttpClientWithUrl};
 use language::LspAdapterDelegate;
 use ui::{prelude::*, ButtonLike, ElevationIndex};
@@ -59,24 +61,26 @@ impl FetchSlashCommand {
 
         match content_type {
             ContentType::Html => {
-                let mut handlers: Vec<Box<dyn HandleTag>> = vec![
-                    Box::new(markdown::ParagraphHandler),
-                    Box::new(markdown::HeadingHandler),
-                    Box::new(markdown::ListHandler),
-                    Box::new(markdown::TableHandler::new()),
-                    Box::new(markdown::StyledTextHandler),
+                let mut handlers: Vec<TagHandler> = vec![
+                    Rc::new(RefCell::new(markdown::ParagraphHandler)),
+                    Rc::new(RefCell::new(markdown::HeadingHandler)),
+                    Rc::new(RefCell::new(markdown::ListHandler)),
+                    Rc::new(RefCell::new(markdown::TableHandler::new())),
+                    Rc::new(RefCell::new(markdown::StyledTextHandler)),
                 ];
                 if url.contains("wikipedia.org") {
                     use html_to_markdown::structure::wikipedia;
 
-                    handlers.push(Box::new(wikipedia::WikipediaChromeRemover));
-                    handlers.push(Box::new(wikipedia::WikipediaInfoboxHandler));
-                    handlers.push(Box::new(wikipedia::WikipediaCodeHandler::new()));
+                    handlers.push(Rc::new(RefCell::new(wikipedia::WikipediaChromeRemover)));
+                    handlers.push(Rc::new(RefCell::new(wikipedia::WikipediaInfoboxHandler)));
+                    handlers.push(Rc::new(
+                        RefCell::new(wikipedia::WikipediaCodeHandler::new()),
+                    ));
                 } else {
-                    handlers.push(Box::new(markdown::CodeHandler));
+                    handlers.push(Rc::new(RefCell::new(markdown::CodeHandler)));
                 }
 
-                convert_html_to_markdown(&body[..], handlers)
+                convert_html_to_markdown(&body[..], &mut handlers)
             }
             ContentType::Plaintext => Ok(std::str::from_utf8(&body)?.to_owned()),
             ContentType::Json => {

crates/assistant/src/slash_command/rustdoc_command.rs

@@ -42,10 +42,9 @@ impl RustdocSlashCommand {
             local_cargo_doc_path.push("index.html");
 
             if let Ok(contents) = fs.load(&local_cargo_doc_path).await {
-                return Ok((
-                    RustdocSource::Local,
-                    convert_rustdoc_to_markdown(contents.as_bytes())?,
-                ));
+                let (markdown, _items) = convert_rustdoc_to_markdown(contents.as_bytes())?;
+
+                return Ok((RustdocSource::Local, markdown));
             }
         }
 
@@ -78,10 +77,9 @@ impl RustdocSlashCommand {
             );
         }
 
-        Ok((
-            RustdocSource::DocsDotRs,
-            convert_rustdoc_to_markdown(&body[..])?,
-        ))
+        let (markdown, _items) = convert_rustdoc_to_markdown(&body[..])?;
+
+        Ok((RustdocSource::DocsDotRs, markdown))
     }
 
     fn path_to_cargo_toml(project: Model<Project>, cx: &mut AppContext) -> Option<Arc<Path>> {