Crabler - Web crawler for Crabs

Structures as asynchronous web crawlers.

Example

use crabweb::*;

#[derive(WebScraper)]
#[on_response(response_handler)]
#[on_html("a[href]", print_handler)]
#[on_html("td.title > a.storylink[href]", follow_handler)]
struct Scraper {}

impl Scraper {
    async fn response_handler(&self, response: Response) -> Result<()> {
        println!("Status {}", response.status);
        Ok(())
    }

    async fn print_handler(&self, response: Response, a: Element) -> Result<()> {
        if let Some(href) = a.attr("href") {
            println!("Found link {} on {}", href, response.url);
        }

        Ok(())
    }

    async fn follow_handler(&self, mut response: Response, a: Element) -> Result<()> {
        if let Some(href) = a.attr("href") {
            response.navigate(href).await?;
        }

        Ok(())
    }
}

#[tokio::main]
async fn main() -> Result<()> {
    let scraper = Scraper { };

    let mut crabweb = CrabWeb::new(scraper);

    // Queue navigation task
    crabweb.navigate("https://news.ycombinator.com/").await?;

    // Create bunch of http workers
    for _ in 0..20 {
        crabweb.start_worker();
    }

    // Run main scraper loop
    crabweb.run().await?;

    Ok(())
}