Strings on web pages

Strings on web pages

What if we want to collect links from web pages:

method findLinks(txt: String) -> String {
  var tagStart: Number
  var tagEnd: Number := 0
  def lowerPage: String = html.asLower
  var tag: String
  var links: String := ""
  var fullPage := txt ++">"  // make sure end search succeeds
  var done: Boolean := false
  while {true} do {
    tagStart := lowerPage.indexOf("<a ")startingAt(tagEnd+1)ifAbsent{
      return links
    }
    tagEnd := lowerPage.indexOf(">")startingAt(tagStart+3) ifAbsent{
      return links
    }
    tag := fullPage.substringFrom(tagStart)to(tagEnd)
    links := links++tag++"\n"
  }
}

Notice how in the above, we search through a version of the string that is all lower case (to make it easy to detect "<a " even if capitalized, but report the string from the original.

Finally, if we want to determine whether something is composed only of digits - i.e., represents an integer:

method isInteger(word:String) -> Boolean {
  for(word) do {letter: String ->
    if (("0" > letter) || (letter > "9")) then {
      return false
    }
  }
  true
}

Strings on web pages