Markdown TOC

use markdown_toc.qweruse toc_headings, toc_markdown from markdown_toc      // Quillo 0.6: only these

pulldown-cmark = { version = "0.12", default-features = false, features = ["html"] }

// A documentation page with its table of contents beside it, and links that jump to each heading.////   quillo run markdown_toc.qwe      then open http://localhost:8080/docsuse "markdown_toc.qwer"let DOC = read_file("markdown_toc_sample.md")?route GET /docs {    let toc = toc_markdown(DOC, 2, 3)?    respond(200, `<nav>${str(markdown(toc))}</nav><main>${toc_html(DOC)?}</main>`, { "content-type": "text/html; charset=utf-8" })}route GET /toc = { markdown: toc_markdown(DOC, 2, 3)?, headings: toc_headings(DOC)? | map((h) => `${h.level} ${h.anchor} (line ${h.line})`) }route GET /tree = toc_tree(DOC)?

//! Tables of contents for Markdown: the headings as a list or a tree with GitHub-style anchors, a ready-made TOC in Markdown, and the page's HTML with those ids on its headings.//! version: 1.0.0//!//! [dependencies]//! pulldown-cmark = { version = "0.12", default-features = false, features = ["html"] }use pulldown_cmark::{CowStr, Event, HeadingLevel, Options, Parser, Tag, TagEnd};use serde_json::{json, Value};use std::collections::HashMap;/// Texts up to 10 MB are read.const MAX: usize = 10 * 1024 * 1024;struct Heading {    level: usize,    text: String,    anchor: String,    line: usize,}fn options() -> Options {    Options::ENABLE_TABLES | Options::ENABLE_STRIKETHROUGH | Options::ENABLE_TASKLISTS | Options::ENABLE_HEADING_ATTRIBUTES | Options::ENABLE_FOOTNOTES}fn level(l: HeadingLevel) -> usize {    match l {        HeadingLevel::H1 => 1,        HeadingLevel::H2 => 2,        HeadingLevel::H3 => 3,        HeadingLevel::H4 => 4,        HeadingLevel::H5 => 5,        HeadingLevel::H6 => 6,    }}/// GitHub's anchor: lower case, punctuation dropped (but `-` and `_`), spaces as `-`.fn slug(text: &str) -> String {    text.trim().to_lowercase().chars().filter_map(|c| {        if c.is_alphanumeric() || c == '-' || c == '_' { Some(c) } else if c == ' ' { Some('-') } else { None }    }).collect()}fn headings(text: &str) -> Result<Vec<Heading>, String> {    if text.len() > MAX {        return Err("Markdown texts up to 10 MB".into());    }    let mut out = vec![];    let mut used: HashMap<String, usize> = HashMap::new();    let mut cur: Option<(usize, Option<String>, String, usize)> = None;    for (ev, range) in Parser::new_ext(text, options()).into_offset_iter() {        match ev {            Event::Start(Tag::Heading { level: l, id, .. }) => {                let line = text[..range.start].matches('\n').count() + 1;                cur = Some((level(l), id.map(|i| i.to_string()), String::new(), line));            }            Event::Text(t) | Event::Code(t) => {                if let Some(c) = cur.as_mut() {                    c.2.push_str(&t);                }            }            Event::End(TagEnd::Heading(_)) => {                if let Some((lvl, id, t, line)) = cur.take() {                    let base = id.unwrap_or_else(|| slug(&t));                    let n = used.entry(base.clone()).or_insert(0);                    let anchor = if *n == 0 { base.clone() } else { format!("{}-{}", base, n) };                    *n += 1;                    out.push(Heading { level: lvl, text: t.trim().to_string(), anchor, line });                }            }            _ => {}        }    }    Ok(out)}/// The headings of `markdown`, in order: `{ level, text, anchor, line }`. `anchor` is the id GitHub (and toc_html) gives the/// heading: `## Getting started` is `getting-started`, a second one `getting-started-1`; `## Setup {#install}` keeps `install`./// `line` counts from 1. Headings inside code blocks are not headings.pub fn toc_headings(markdown: &str) -> Result<Vec<Value>, String> {    Ok(headings(markdown)?.iter().map(|h| json!({ "level": h.level, "text": h.text, "anchor": h.anchor, "line": h.line })).collect())}/// A table of contents in Markdown, a nested list of links to the headings from level `min_level` to `max_level` (1 to 6;/// 2 and 3 skip the page's title and keep it short): `- [Getting started](#getting-started)`.pub fn toc_markdown(markdown: &str, min_level: i64, max_level: i64) -> Result<String, String> {    let (lo, hi) = (min_level.clamp(1, 6) as usize, max_level.clamp(1, 6) as usize);    let hs: Vec<Heading> = headings(markdown)?.into_iter().filter(|h| h.level >= lo && h.level <= hi).collect();    let top = hs.iter().map(|h| h.level).min().unwrap_or(lo);    let mut out = String::new();    for h in &hs {        let label = h.text.replace('[', "\\[").replace(']', "\\]");        out.push_str(&format!("{}- [{}](#{})\n", "  ".repeat(h.level - top), label, h.anchor));    }    Ok(out)}/// The headings as a tree: `{ level, text, anchor, children }`, each heading under the nearest one above it of a smaller level.pub fn toc_tree(markdown: &str) -> Result<Vec<Value>, String> {    fn take(hs: &[Heading], i: &mut usize, parent: usize) -> Vec<Value> {        let mut out = vec![];        while *i < hs.len() && hs[*i].level > parent {            let h = &hs[*i];            *i += 1;            let children = take(hs, i, h.level);            out.push(json!({ "level": h.level, "text": h.text, "anchor": h.anchor, "children": children }));        }        out    }    let hs = headings(markdown)?;    let mut i = 0;    Ok(take(&hs, &mut i, 0))}/// The page as HTML with each heading's `id` set to its anchor, so the table of contents' links work. HTML written inside/// the Markdown is shown as text, not run, so the page is safe for what visitors write; tables, task lists, strikethrough/// and footnotes are on.pub fn toc_html(markdown: &str) -> Result<String, String> {    let hs = headings(markdown)?;    let mut ids = hs.iter().map(|h| h.anchor.clone());    let events = Parser::new_ext(markdown, options()).map(|ev| match ev {        Event::Start(Tag::Heading { level, classes, attrs, .. }) => Event::Start(Tag::Heading { level, id: ids.next().map(CowStr::from), classes, attrs }),        Event::Html(h) | Event::InlineHtml(h) => Event::Text(h),        other => other,    });    let mut out = String::new();    pulldown_cmark::html::push_html(&mut out, events);    Ok(out)}