From 55a05ea736087fc6f9282466e0789b745679dd37 Mon Sep 17 00:00:00 2001
From: beauvill <charles.beauville@epfl.ch>
Date: Tue, 8 Oct 2019 11:31:01 +0200
Subject: [PATCH] Finished homework 3

---
 src/main/scala/objsets/TweetSet.scala | 39 ++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/src/main/scala/objsets/TweetSet.scala b/src/main/scala/objsets/TweetSet.scala
index ac88c95..a4c1b4f 100644
--- a/src/main/scala/objsets/TweetSet.scala
+++ b/src/main/scala/objsets/TweetSet.scala
@@ -41,12 +41,13 @@ abstract class TweetSet extends TweetSetInterface {
    * Question: Can we implment this method here, or should it remain abstract
    * 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.
    */
-  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`.
@@ -54,7 +55,7 @@ abstract class TweetSet extends TweetSetInterface {
    * Question: Should we implment this method here, or should it remain abstract
    * 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.
@@ -65,7 +66,7 @@ abstract class TweetSet extends TweetSetInterface {
    * Question: Should we implment this method here, or should it remain abstract
    * 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
@@ -76,7 +77,7 @@ abstract class TweetSet extends TweetSetInterface {
    * Question: Should we implment this method here, or should it remain abstract
    * and be implemented in the subclasses?
    */
-  def descendingByRetweet: TweetList = ???
+  def descendingByRetweet: TweetList
 
   /**
    * The following methods are already implemented
@@ -107,7 +108,11 @@ abstract class TweetSet extends TweetSetInterface {
 }
 
 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
@@ -124,8 +129,22 @@ class Empty 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
@@ -185,14 +204,14 @@ object GoogleVsApple {
   val google = List("android", "Android", "galaxy", "Galaxy", "nexus", "Nexus")
   val apple = List("ios", "iOS", "iphone", "iPhone", "ipad", "iPad")
 
-  lazy val googleTweets: TweetSet = ???
-  lazy val appleTweets: TweetSet = ???
+  lazy val googleTweets: TweetSet = TweetReader.allTweets.filter(tweet => google.exists(elem => tweet.text.contains(elem)))
+  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,
    * sorted by the number of retweets.
    */
-  lazy val trending: TweetList = ???
+  lazy val trending: TweetList = googleTweets.union(appleTweets).descendingByRetweet
 }
 
 object Main extends App {