assistant: Add /rustdoc slash command (#12453)

This PR adds a `/rustdoc` slash command for retrieving and inserting
rustdoc docs into the Assistant.

Right now the command accepts the crate name as an argument and will
return the top-level docs from `docs.rs`.

Release Notes:

- N/A

crates/rustdoc_to_markdown/src/markdown_writer.rs

@@ -36,12 +36,6 @@ impl MarkdownWriter {
             .any(|parent_element| parent_element.tag == tag)
     }
 
-    fn is_inside_heading(&self) -> bool {
-        ["h1", "h2", "h3", "h4", "h5", "h6"]
-            .into_iter()
-            .any(|heading| self.is_inside(heading))
-    }
-
     /// Appends the given string slice onto the end of the Markdown output.
     fn push_str(&mut self, str: &str) {
         self.markdown.push_str(str);
@@ -135,16 +129,14 @@ impl MarkdownWriter {
                 }
             }
             "div" | "span" => {
-                if tag.attrs.borrow().iter().any(|attr| {
-                    attr.name.local.to_string() == "class"
-                        && attr.value.to_string() == "sidebar-elems"
-                }) {
-                    return StartTagOutcome::Skip;
-                }
+                let classes_to_skip = ["nav-container", "sidebar-elems", "out-of-band"];
 
                 if tag.attrs.borrow().iter().any(|attr| {
                     attr.name.local.to_string() == "class"
-                        && attr.value.to_string() == "out-of-band"
+                        && attr
+                            .value
+                            .split(' ')
+                            .any(|class| classes_to_skip.contains(&class.trim()))
                 }) {
                     return StartTagOutcome::Skip;
                 }
@@ -189,10 +181,6 @@ impl MarkdownWriter {
             return Ok(());
         }
 
-        if self.is_inside_heading() && self.is_inside("a") {
-            return Ok(());
-        }
-
         let trimmed_text = text.trim_matches(|char| char == '\n' || char == '\r' || char == '§');
         self.push_str(trimmed_text);
 

crates/rustdoc_to_markdown/src/rustdoc_to_markdown.rs

@@ -4,6 +4,8 @@
 
 mod markdown_writer;
 
+use std::io::Read;
+
 use anyhow::{Context, Result};
 use html5ever::driver::ParseOpts;
 use html5ever::parse_document;
@@ -14,7 +16,7 @@ use markup5ever_rcdom::RcDom;
 use crate::markdown_writer::MarkdownWriter;
 
 /// Converts the provided rustdoc HTML to Markdown.
-pub fn convert_rustdoc_to_markdown(html: &str) -> Result<String> {
+pub fn convert_rustdoc_to_markdown(mut html: impl Read) -> Result<String> {
     let parse_options = ParseOpts {
         tree_builder: TreeBuilderOpts {
             drop_doctype: true,
@@ -24,7 +26,7 @@ pub fn convert_rustdoc_to_markdown(html: &str) -> Result<String> {
     };
     let dom = parse_document(RcDom::default(), parse_options)
         .from_utf8()
-        .read_from(&mut html.as_bytes())
+        .read_from(&mut html)
         .context("failed to parse rustdoc HTML")?;
 
     let markdown_writer = MarkdownWriter::new();