# Crabler - Web crawler for Crabs
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[mit-url]: LICENSE
Structures as asynchronous web crawlers.
Goal of this library is to help crabs with web crawling.
## Example
```rust
extern crate crabler;
use crabler::*;
#[derive(WebScraper)]
#[on_response(response_handler)]
#[on_html("a[href]", print_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_std::main]
async fn main() -> Result<()> {
let scraper = Scraper {};
// Run scraper starting from given url and using 20 worker threads
scraper.run(Opts::new().with_urls(vec!["https://news.ycombinator.com/"]).with_threads(20)).await
}
```