// A crawler which checks whether there+ −
// are problems with links in web-pages+ −
+ −
import io.Source+ −
import scala.util.matching.Regex+ −
import scala.util._+ −
+ −
// gets the first 10K of a web-page+ −
def get_page(url: String) : String = {+ −
Try(Source.fromURL(url).take(10000).mkString) getOrElse + −
{ println(s" Problem with: $url"); ""}+ −
}+ −
+ −
// regex for URLs+ −
val http_pattern = """\"https?://[^\"]*\"""".r+ −
+ −
// drops the first and last character from a string+ −
def unquote(s: String) = s.drop(1).dropRight(1)+ −
+ −
def get_all_URLs(page: String) : Set[String] = {+ −
http_pattern.findAllIn(page).map(unquote).toSet+ −
}+ −
+ −
// naive version - seraches until a given depth+ −
// visits pages potentially more than once+ −
def crawl(url: String, n: Int) : Unit = {+ −
if (n == 0) ()+ −
else {+ −
println(s"Visiting: $n $url")+ −
for (u <- get_all_URLs(get_page(url))) crawl(u, n - 1)+ −
}+ −
}+ −
+ −
// staring URL for the crawler+ −
val startURL = """http://www.inf.kcl.ac.uk/staff/urbanc/"""+ −
//val startURL = """http://www.inf.kcl.ac.uk/staff/mml/"""+ −
+ −
crawl(startURL, 2)+ −
+ −