Clone-less toc making

components/rendering/src/markdown.rs

@@ -12,7 +12,7 @@ use context::RenderContext;
 use errors::{Error, Result};
 use front_matter::InsertAnchor;
 use link_checker::check_url;
-use table_of_contents::{Header, make_table_of_contents, TempHeader};
+use table_of_contents::{Header, make_table_of_contents};
 use utils::site::resolve_internal_link;
 use utils::vec::InsertMany;
 
@@ -140,7 +140,7 @@ pub fn markdown_to_html(content: &str, context: &RenderContext) -> Result<Render
     let mut highlighter: Option<(HighlightLines, bool)> = None;
 
     let mut inserted_anchors: Vec<String> = vec![];
-    let mut headers: Vec<TempHeader> = vec![];
+    let mut headers: Vec<Header> = vec![];
 
     let mut opts = Options::empty();
     let mut has_summary = false;
@@ -253,8 +253,8 @@ pub fn markdown_to_html(content: &str, context: &RenderContext) -> Result<Render
 
             // record header to make table of contents
             let permalink = format!("{}#{}", context.current_page_permalink, id);
-            let temp_header = TempHeader { level: header_ref.level, id, permalink, title };
-            headers.push(temp_header);
+            let h = Header { level: header_ref.level, id, permalink, title, children: Vec::new() };
+            headers.push(h);
         }
 
         if context.insert_anchor != InsertAnchor::None {
@@ -270,7 +270,7 @@ pub fn markdown_to_html(content: &str, context: &RenderContext) -> Result<Render
         Ok(Rendered {
             summary_len: if has_summary { html.find(CONTINUE_READING) } else { None },
             body: html,
-            toc: make_table_of_contents(&headers),
+            toc: make_table_of_contents(headers),
         })
     }
 }

components/rendering/src/table_of_contents.rs

@@ -1,112 +1,59 @@
+/// Populated while receiving events from the markdown parser
 #[derive(Debug, PartialEq, Clone, Serialize)]
 pub struct Header {
     #[serde(skip_serializing)]
     pub level: i32,
     pub id: String,
-    pub title: String,
     pub permalink: String,
+    pub title: String,
     pub children: Vec<Header>,
 }
 
 impl Header {
-    pub fn from_temp_header(tmp: &TempHeader, children: Vec<Header>) -> Header {
+    pub fn new(level: i32) -> Header {
         Header {
-            level: tmp.level,
-            id: tmp.id.clone(),
-            title: tmp.title.clone(),
-            permalink: tmp.permalink.clone(),
-            children,
-        }
-    }
-}
-
-/// Populated while receiving events from the markdown parser
-#[derive(Debug, PartialEq, Clone)]
-pub struct TempHeader {
-    pub level: i32,
-    pub id: String,
-    pub permalink: String,
-    pub title: String,
-}
-
-impl TempHeader {
-    pub fn new(level: i32) -> TempHeader {
-        TempHeader {
             level,
             id: String::new(),
             permalink: String::new(),
             title: String::new(),
+            children: Vec::new(),
         }
     }
 }
 
-impl Default for TempHeader {
+impl Default for Header {
     fn default() -> Self {
-        TempHeader::new(0)
-    }
-}
-
-/// Recursively finds children of a header
-fn find_children(
-    parent_level: i32,
-    start_at: usize,
-    temp_headers: &[TempHeader],
-) -> (usize, Vec<Header>) {
-    let mut headers = vec![];
-
-    let mut start_at = start_at;
-    // If we have children, we will need to skip some headers since they are already inserted
-    let mut to_skip = 0;
-
-    for h in &temp_headers[start_at..] {
-        // stop when we encounter a title at the same level or higher
-        // than the parent one. Here a lower integer is considered higher as we are talking about
-        // HTML headers: h1, h2, h3, h4, h5 and h6
-        if h.level <= parent_level {
-            return (start_at, headers);
-        }
-
-        // Do we need to skip some headers?
-        if to_skip > 0 {
-            to_skip -= 1;
-            continue;
-        }
-
-        let (end, children) = find_children(h.level, start_at + 1, temp_headers);
-        headers.push(Header::from_temp_header(h, children));
-
-        // we didn't find any children
-        if end == start_at {
-            start_at += 1;
-            to_skip = 0;
-        } else {
-            // calculates how many we need to skip. Since the find_children start_at starts at 1,
-            // we need to remove 1 to ensure correctness
-            to_skip = end - start_at - 1;
-            start_at = end;
-        }
-
-        // we don't want to index out of bounds
-        if start_at + 1 > temp_headers.len() {
-            return (start_at, headers);
-        }
+        Header::new(0)
     }
-
-    (start_at, headers)
 }
 
 /// Converts the flat temp headers into a nested set of headers
 /// representing the hierarchy
-pub fn make_table_of_contents(temp_headers: &[TempHeader]) -> Vec<Header> {
+pub fn make_table_of_contents(headers: Vec<Header>) -> Vec<Header> {
     let mut toc = vec![];
-    let mut start_idx = 0;
-    for (i, h) in temp_headers.iter().enumerate() {
-        if i < start_idx {
+    'parent: for header in headers {
+        if toc.is_empty() {
+            toc.push(header);
             continue;
         }
-        let (end_idx, children) = find_children(h.level, start_idx + 1, temp_headers);
-        start_idx = end_idx;
-        toc.push(Header::from_temp_header(h, children));
+
+        // See if we have to insert as a child of a previous header
+        for h in toc.iter_mut().rev() {
+            // Look in its children first
+            for child in h.children.iter_mut().rev() {
+                if header.level > child.level {
+                    child.children.push(header);
+                    continue 'parent;
+                }
+            }
+            if header.level > h.level {
+                h.children.push(header);
+                continue 'parent;
+            }
+        }
+
+        // Nop, just insert it
+        toc.push(header)
     }
 
     toc
@@ -118,25 +65,25 @@ mod tests {
 
     #[test]
     fn can_make_basic_toc() {
-        let input = vec![TempHeader::new(1), TempHeader::new(1), TempHeader::new(1)];
-        let toc = make_table_of_contents(&input);
+        let input = vec![Header::new(1), Header::new(1), Header::new(1)];
+        let toc = make_table_of_contents(input);
         assert_eq!(toc.len(), 3);
     }
 
     #[test]
     fn can_make_more_complex_toc() {
         let input = vec![
-            TempHeader::new(1),
-            TempHeader::new(2),
-            TempHeader::new(2),
-            TempHeader::new(3),
-            TempHeader::new(2),
-            TempHeader::new(1),
-            TempHeader::new(2),
-            TempHeader::new(3),
-            TempHeader::new(3),
+            Header::new(1),
+            Header::new(2),
+            Header::new(2),
+            Header::new(3),
+            Header::new(2),
+            Header::new(1),
+            Header::new(2),
+            Header::new(3),
+            Header::new(3),
         ];
-        let toc = make_table_of_contents(&input);
+        let toc = make_table_of_contents(input);
         assert_eq!(toc.len(), 2);
         assert_eq!(toc[0].children.len(), 3);
         assert_eq!(toc[1].children.len(), 1);
@@ -147,15 +94,16 @@ mod tests {
     #[test]
     fn can_make_messy_toc() {
         let input = vec![
-            TempHeader::new(3),
-            TempHeader::new(2),
-            TempHeader::new(2),
-            TempHeader::new(3),
-            TempHeader::new(2),
-            TempHeader::new(1),
-            TempHeader::new(4),
+            Header::new(3),
+            Header::new(2),
+            Header::new(2),
+            Header::new(3),
+            Header::new(2),
+            Header::new(1),
+            Header::new(4),
         ];
-        let toc = make_table_of_contents(&input);
+        let toc = make_table_of_contents(input);
+        println!("{:#?}", toc);
         assert_eq!(toc.len(), 5);
         assert_eq!(toc[2].children.len(), 1);
         assert_eq!(toc[4].children.len(), 1);