docs_build.rs

#!/usr/bin/env run-cargo-script
//! This is a regular crate doc comment, but it also contains a partial
//! Cargo manifest.  Note the use of a *fenced* code block, and the
//! `cargo` "language".
//!
//! ```cargo
//! [dependencies]
//! heck = "0.3.1"
//! pulldown-cmark = "0.5.2"
//! ```

extern crate heck;
extern crate pulldown_cmark;

use heck::KebabCase;
use pulldown_cmark::{html, CowStr, Event, Options, Parser, Tag};
use std::fs::File;
use std::io::prelude::*;
use std::io::BufReader;

fn main() -> std::io::Result<()> {
    let file = File::open("README.md")?;
    let mut buf_reader = BufReader::new(file);
    let mut contents = String::new();
    buf_reader.read_to_string(&mut contents)?;

    let options = Options::all();
    let parser = Parser::new_ext(contents.as_str(), options);
    let mut in_header_level = 0;
    let parser = parser.map(|event| match event {
        Event::Start(Tag::Header(num)) => {
            in_header_level = num;
            Event::Html(CowStr::Borrowed(""))
        }
        Event::Text(text) => {
            if in_header_level > 0 {
                let result_html = format!(
                    "<h{} id=\"{}\">{}</h{}>",
                    in_header_level,
                    text.to_kebab_case(),
                    text,
                    in_header_level
                );
                Event::Html(result_html.into())
            } else {
                Event::Text(text)
            }
        }
        Event::End(Tag::Header(_)) => {
            in_header_level = 0;
            event
        }
        _ => event,
    });

    // Write to String buffer.
    let mut html_output = String::new();
    html::push_html(&mut html_output, parser);

    let template = File::open("docs_template.html")?;
    let mut contents = String::new();
    buf_reader = BufReader::new(template);
    buf_reader.read_to_string(&mut contents)?;
    contents = contents.replace("%%content%%", &html_output);

    let mut file = File::create("docs/index.html")?;
    file.write_all(contents.as_bytes())
}