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import io.Source
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import scala.util.matching.Regex
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// gets the first ~10K of a page
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def get_page(url: String) : String = {
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try {
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Source.fromURL(url).take(10000).mkString
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}
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catch {
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case e => {
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println(" Problem with: " + url)
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""
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}
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}
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}
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// staring URL for the crawler
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val startURL = """http://www.inf.kcl.ac.uk/staff/urbanc/"""
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// regex for URLs
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val http_pattern = """\"https?://[^\"]*\"""".r
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val my_urls = """urbanc""".r
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def unquote(s: String) = s.drop(1).dropRight(1)
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def get_all_URLs(page: String) : Set[String] = {
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(http_pattern.findAllIn(page)).map { unquote(_) }.toSet
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}
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// naive version - seraches until a given depth
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// visits pages potentially more than once
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def crawl(url: String, n: Int) : Unit = {
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if (n == 0) ()
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else if (my_urls.findFirstIn(url) == None) ()
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else {
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println("Visiting: " + n + " " + url)
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for (u <- get_all_URLs(get_page(url))) crawl(u, n - 1)
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}
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}
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// can now deal with depth 3
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3
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// start on command line
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7
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crawl(startURL, 4)
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1
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