1 files changed, 120 insertions, 0 deletions
diff --git a/main/api/src/mill/api/AggWrapper.scala b/main/api/src/mill/api/AggWrapper.scala
new file mode 100644
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+++ b/main/api/src/mill/api/AggWrapper.scala
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+package mill.api
+
+
+
+import scala.collection.mutable
+object Strict extends AggWrapper(true)
+object Loose extends AggWrapper(false)
+
+sealed class AggWrapper(strictUniqueness: Boolean){
+  /**
+    * A collection with enforced uniqueness, fast contains and deterministic
+    * ordering. Raises an exception if a duplicate is found; call
+    * `toSeq.distinct` if you explicitly want to make it swallow duplicates
+    */
+  trait Agg[V] extends TraversableOnce[V]{
+    def contains(v: V): Boolean
+    def items: Iterator[V]
+    def indexed: IndexedSeq[V]
+    def flatMap[T](f: V => TraversableOnce[T]): Agg[T]
+    def map[T](f: V => T): Agg[T]
+    def filter(f: V => Boolean): Agg[V]
+    def withFilter(f: V => Boolean): Agg[V]
+    def collect[T](f: PartialFunction[V, T]): Agg[T]
+    def zipWithIndex: Agg[(V, Int)]
+    def reverse: Agg[V]
+    def zip[T](other: Agg[T]): Agg[(V, T)]
+    def ++[T >: V](other: TraversableOnce[T]): Agg[T]
+    def length: Int
+  }
+
+  object Agg{
+    def empty[V]: Agg[V] = new Agg.Mutable[V]
+    implicit def jsonFormat[T: upickle.default.ReadWriter]: upickle.default.ReadWriter[Agg[T]] =
+      upickle.default.readwriter[Seq[T]].bimap[Agg[T]](
+        _.toList,
+        Agg.from(_)
+      )
+
+    def apply[V](items: V*) = from(items)
+
+    implicit def from[V](items: TraversableOnce[V]): Agg[V] = {
+      val set = new Agg.Mutable[V]()
+      items.foreach(set.append)
+      set
+    }
+
+
+    class Mutable[V]() extends Agg[V]{
+
+      private[this] val set0 = mutable.LinkedHashSet.empty[V]
+      def contains(v: V) = set0.contains(v)
+      def append(v: V) = if (!contains(v)){
+        set0.add(v)
+
+      }else if (strictUniqueness){
+        throw new Exception("Duplicated item inserted into OrderedSet: " + v)
+      }
+      def appendAll(vs: Seq[V]) = vs.foreach(append)
+      def items = set0.iterator
+      def indexed: IndexedSeq[V] = items.toIndexedSeq
+      def set: collection.Set[V] = set0
+
+      def map[T](f: V => T): Agg[T] = {
+        val output = new Agg.Mutable[T]
+        for(i <- items) output.append(f(i))
+        output
+      }
+      def flatMap[T](f: V => TraversableOnce[T]): Agg[T] = {
+        val output = new Agg.Mutable[T]
+        for(i <- items) for(i0 <- f(i)) output.append(i0)
+        output
+      }
+      def filter(f: V => Boolean): Agg[V] = {
+        val output = new Agg.Mutable[V]
+        for(i <- items) if (f(i)) output.append(i)
+        output
+      }
+      def withFilter(f: V => Boolean): Agg[V] = filter(f)
+
+      def collect[T](f: PartialFunction[V, T]) = this.filter(f.isDefinedAt).map(x => f(x))
+
+      def zipWithIndex = {
+        var i = 0
+        this.map{ x =>
+          i += 1
+          (x, i-1)
+        }
+      }
+
+      def reverse = Agg.from(indexed.reverseIterator)
+
+      def zip[T](other: Agg[T]) = Agg.from(items.zip(other.items))
+      def ++[T >: V](other: TraversableOnce[T]) = Agg.from(items ++ other)
+      def length: Int = set0.size
+
+      // Members declared in scala.collection.GenTraversableOnce
+      def isTraversableAgain: Boolean = items.isTraversableAgain
+      def toIterator: Iterator[V] = items.toIterator
+      def toStream: Stream[V] = items.toStream
+
+      // Members declared in scala.collection.TraversableOnce
+      def copyToArray[B >: V](xs: Array[B], start: Int,len: Int): Unit = items.copyToArray(xs, start, len)
+      def exists(p: V => Boolean): Boolean = items.exists(p)
+      def find(p: V => Boolean): Option[V] = items.find(p)
+      def forall(p: V => Boolean): Boolean = items.forall(p)
+      def foreach[U](f: V => U): Unit = items.foreach(f)
+      def hasDefiniteSize: Boolean = items.hasDefiniteSize
+      def isEmpty: Boolean = items.isEmpty
+      def seq: scala.collection.TraversableOnce[V] = items
+      def toTraversable: Traversable[V] = items.toTraversable
+
+      override def hashCode() = items.map(_.hashCode()).sum
+      override def equals(other: Any) = other match{
+        case s: Agg[_] => items.sameElements(s.items)
+        case _ => super.equals(other)
+      }
+      override def toString = items.mkString("Agg(", ", ", ")")
+    }
+  }
+}