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Finished homework 3

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This commit is contained in:
beauvill 2019-10-08 11:31:01 +02:00
parent 4f98102c94
commit 55a05ea736
1 changed files with 29 additions and 10 deletions
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39
src/main/scala/objsets/TweetSet.scala
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@ -41,12 +41,13 @@ abstract class TweetSet extends TweetSetInterface {
* Question: Can we implment this method here, or should it remain abstract * Question: Can we implment this method here, or should it remain abstract
* and be implemented in the subclasses? * and be implemented in the subclasses?
*/ */
def filter(p: Tweet => Boolean): TweetSet = ??? def filter(p: Tweet => Boolean): TweetSet = filterAcc(p, new Empty)
/** /**
* This is a helper method for `filter` that propagetes the accumulated tweets. * This is a helper method for `filter` that propagetes the accumulated tweets.
*/ */
def filterAcc(p: Tweet => Boolean, acc: TweetSet): TweetSet def filterAcc(p: Tweet => Boolean, acc: TweetSet): TweetSet
/** /**
* Returns a new `TweetSet` that is the union of `TweetSet`s `this` and `that`. * Returns a new `TweetSet` that is the union of `TweetSet`s `this` and `that`.
@ -54,7 +55,7 @@ abstract class TweetSet extends TweetSetInterface {
* Question: Should we implment this method here, or should it remain abstract * Question: Should we implment this method here, or should it remain abstract
* and be implemented in the subclasses? * and be implemented in the subclasses?
*/ */
def union(that: TweetSet): TweetSet = ??? def union(that: TweetSet): TweetSet = that.filterAcc(elem => true, this)
/** /**
* Returns the tweet from this set which has the greatest retweet count. * Returns the tweet from this set which has the greatest retweet count.
@ -65,7 +66,7 @@ abstract class TweetSet extends TweetSetInterface {
* Question: Should we implment this method here, or should it remain abstract * Question: Should we implment this method here, or should it remain abstract
* and be implemented in the subclasses? * and be implemented in the subclasses?
*/ */
def mostRetweeted: Tweet = ??? def mostRetweeted: Tweet
/** /**
* Returns a list containing all tweets of this set, sorted by retweet count * Returns a list containing all tweets of this set, sorted by retweet count
@ -76,7 +77,7 @@ abstract class TweetSet extends TweetSetInterface {
* Question: Should we implment this method here, or should it remain abstract * Question: Should we implment this method here, or should it remain abstract
* and be implemented in the subclasses? * and be implemented in the subclasses?
*/ */
def descendingByRetweet: TweetList = ??? def descendingByRetweet: TweetList
/** /**
* The following methods are already implemented * The following methods are already implemented
@ -107,7 +108,11 @@ abstract class TweetSet extends TweetSetInterface {
} }
class Empty extends TweetSet { class Empty extends TweetSet {
def filterAcc(p: Tweet => Boolean, acc: TweetSet): TweetSet = ??? def filterAcc(p: Tweet => Boolean, acc: TweetSet): TweetSet = acc
def mostRetweeted: Tweet = throw new java.util.NoSuchElementException
def descendingByRetweet: TweetList = Nil
/** /**
* The following methods are already implemented * The following methods are already implemented
@ -124,8 +129,22 @@ class Empty extends TweetSet {
class NonEmpty(elem: Tweet, left: TweetSet, right: TweetSet) extends TweetSet { class NonEmpty(elem: Tweet, left: TweetSet, right: TweetSet) extends TweetSet {
def filterAcc(p: Tweet => Boolean, acc: TweetSet): TweetSet = ??? def filterAcc(p: Tweet => Boolean, acc: TweetSet): TweetSet =
if (p(elem)) then
left.filterAcc(p, right.filterAcc(p, acc.incl(elem)))
else
left.filterAcc(p, right.filterAcc(p, acc))
def mostRetweeted: Tweet = {
var mostRet: Tweet = elem
(left union right).foreach(t => if (t.retweets > mostRet.retweets) then mostRet = t)
mostRet
}
def descendingByRetweet: TweetList = {
val mostRet: Tweet = mostRetweeted
new Cons(mostRet,remove(mostRet).descendingByRetweet)
}
/** /**
* The following methods are already implemented * The following methods are already implemented
@ -185,14 +204,14 @@ object GoogleVsApple {
val google = List("android", "Android", "galaxy", "Galaxy", "nexus", "Nexus") val google = List("android", "Android", "galaxy", "Galaxy", "nexus", "Nexus")
val apple = List("ios", "iOS", "iphone", "iPhone", "ipad", "iPad") val apple = List("ios", "iOS", "iphone", "iPhone", "ipad", "iPad")
lazy val googleTweets: TweetSet = ??? lazy val googleTweets: TweetSet = TweetReader.allTweets.filter(tweet => google.exists(elem => tweet.text.contains(elem)))
lazy val appleTweets: TweetSet = ??? lazy val appleTweets: TweetSet = TweetReader.allTweets.filter(tweet => apple.exists(elem => tweet.text.contains(elem)))
/** /**
* A list of all tweets mentioning a keyword from either apple or google, * A list of all tweets mentioning a keyword from either apple or google,
* sorted by the number of retweets. * sorted by the number of retweets.
*/ */
lazy val trending: TweetList = ??? lazy val trending: TweetList = googleTweets.union(appleTweets).descendingByRetweet
} }
object Main extends App { object Main extends App {