Script Library: 1222 scripts
 

webcrawler.r

REBOL [ Title: "REBOL Web Crawler" Date: 16-Sep-1999 File: %webcrawler.r Author: "Bohdan Lechnowsky" Purpose: { To crawl the web starting from any site. Does not record duplicate visits. Saves all links found in 'newlinks. } Email: %bo--rebol--com Comments: { Based on my previous script, %rebol-web-miner.r } library: [ level: 'advanced platform: none type: 'tool domain: [web other-net] tested-under: none support: none license: none see-also: none ] ] find-links: func [ "Finds 'href' links and outputs them as a block" url [url!] "The site currently being checked" html [string!] "The HTML text to parse" ][ links: make block! 0 site: tail form url while [(copy/part site: back site 1) <> "/"][] site: to-url head clear next site while [html: find html "href"] [ link: (trim (copy/part (next (find html "=")) (html: find html ">"))) if not found? find link "mailto:" [ link: trim/with link {"} if (copy/part form link 7) <> "http://" [ link: head clean-path join site link ] append links to-url link ] ] return links ] urls: [http://www.rebol.com/] newlinks: make block! 0 sites: make block! 0 while [true] [ foreach url urls [ either find sites url [ print [url "already visited"] ][ print [" READING" url] append newlinks url append sites url either not error? try [read-url: read url] [ foreach link find-links url read-url [ if none? find newlinks link [ append newlinks link ] ] ][ print [" Error reading" url] ] ] ] urls: newlinks ]
halt ;; to terminate script if DO'ne from webpage
Notes
  • email address(es) have been munged to protect them from spam harvesters. If you are a Library member, you can log on and view this script without the munging.
  • (bo:rebol:com)