zola/components/rendering/src/table_of_contents.rs

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#[derive(Debug, PartialEq, Clone, Serialize)]
pub struct Header {
#[serde(skip_serializing)]
pub level: i32,
pub id: String,
pub title: String,
pub permalink: String,
pub children: Vec<Header>,
}
impl Header {
pub fn from_temp_header(tmp: &TempHeader, children: Vec<Header>) -> Header {
Header {
level: tmp.level,
id: tmp.id.clone(),
title: tmp.title.clone(),
permalink: tmp.permalink.clone(),
children,
}
}
}
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/// Populated while receiving events from the markdown parser
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#[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(),
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}
}
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}
impl Default for TempHeader {
fn default() -> Self {
TempHeader::new(0)
}
}
/// Recursively finds children of a header
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fn find_children(
parent_level: i32,
start_at: usize,
temp_headers: &[TempHeader],
) -> (usize, Vec<Header>) {
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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;
}
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let (end, children) = find_children(h.level, start_at + 1, temp_headers);
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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);
}
}
(start_at, headers)
}
/// Converts the flat temp headers into a nested set of headers
/// representing the hierarchy
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pub fn make_table_of_contents(temp_headers: &[TempHeader]) -> Vec<Header> {
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let mut toc = vec![];
let mut start_idx = 0;
for (i, h) in temp_headers.iter().enumerate() {
if i < start_idx {
continue;
}
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let (end_idx, children) = find_children(h.level, start_idx + 1, temp_headers);
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start_idx = end_idx;
toc.push(Header::from_temp_header(h, children));
}
toc
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn can_make_basic_toc() {
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let input = vec![TempHeader::new(1), TempHeader::new(1), TempHeader::new(1)];
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let toc = make_table_of_contents(&input);
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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),
];
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let toc = make_table_of_contents(&input);
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assert_eq!(toc.len(), 2);
assert_eq!(toc[0].children.len(), 3);
assert_eq!(toc[1].children.len(), 1);
assert_eq!(toc[0].children[1].children.len(), 1);
assert_eq!(toc[1].children[0].children.len(), 2);
}
#[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),
];
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let toc = make_table_of_contents(&input);
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assert_eq!(toc.len(), 5);
assert_eq!(toc[2].children.len(), 1);
assert_eq!(toc[4].children.len(), 1);
}
}