Made SimpleMap non-variant in key type and added map2 method.

Better type for foreachKey that way.

1 files changed, 32 insertions, 16 deletions

diff --git a/src/dotty/tools/dotc/util/SimpleMap.scala b/src/dotty/tools/dotc/util/SimpleMap.scala
index 3acc5c4b8..f4f238c5e 100644
--- a/src/dotty/tools/dotc/util/SimpleMap.scala
+++ b/src/dotty/tools/dotc/util/SimpleMap.scala
@@ -1,17 +1,31 @@
 package dotty.tools.dotc.util
 
-abstract class SimpleMap[-K, +V >: Null] {
+import collection.mutable.ListBuffer
+
+abstract class SimpleMap[K, +V >: Null] {
   def apply(k: K): V
   def remove(k: K): SimpleMap[K, V]
   def updated[V1 >: V](k: K, v: V1): SimpleMap[K, V1]
   def contains(k: K): Boolean = apply(k) != null
   def mapValues[V1 >: V](f: V1 => V1): SimpleMap[K, V1]
-  def foreachKey(f: Any => Unit): Unit
+  def foreachKey(f: K => Unit): Unit
+  def map2[T](f: (K, V) => T): List[T] = {
+    val buf = new ListBuffer[T]
+    foreachKey { key =>
+      val k = key.asInstanceOf[K]
+      buf += f(k, this(k))
+    }
+    buf.toList
+  }
+  override def toString = {
+    def assocToString(key: K, value: V) = s"$key -> $value"
+    map2(assocToString) mkString ("(", ", ", ")")
+  }
 }
 
 object SimpleMap {
 
-  object Empty extends SimpleMap[Any, Null] {
+  private object myEmpty extends SimpleMap[Any, Null] {
     def apply(k: Any) = null
     def remove(k: Any) = this
     def updated[V1 >: Null](k: Any, v: V1) = new Map1(k, v)
@@ -19,22 +33,24 @@ object SimpleMap {
     def foreachKey(f: Any => Unit) = ()
   }
 
-  class Map1[-K, +V >: Null] (k1: K, v1: V) extends SimpleMap[K, V] {
+  def Empty[K] = myEmpty.asInstanceOf[SimpleMap[K, Null]]
+
+  class Map1[K, +V >: Null] (k1: K, v1: V) extends SimpleMap[K, V] {
     def apply(k: K) =
       if (k == k1) v1
       else null
     def remove(k: K) =
-      if (k == k1) Empty
+      if (k == k1) Empty.asInstanceOf[SimpleMap[K, V]]
       else this
     def updated[V1 >: V](k: K, v: V1) =
       if (k == k1) new Map1(k, v)
       else new Map2(k1, v1, k, v)
     def mapValues[V1 >: V](f: V1 => V1) =
       new Map1(k1, f(v1))
-    def foreachKey(f: Any => Unit) = f(k1)
+    def foreachKey(f: K => Unit) = f(k1)
   }
 
-  class Map2[-K, +V >: Null] (k1: K, v1: V, k2: K, v2: V) extends SimpleMap[K, V] {
+  class Map2[K, +V >: Null] (k1: K, v1: V, k2: K, v2: V) extends SimpleMap[K, V] {
     def apply(k: K) =
       if (k == k1) v1
       else if (k == k2) v2
@@ -49,10 +65,10 @@ object SimpleMap {
       else new Map3(k1, v1, k2, v2, k, v)
     def mapValues[V1 >: V](f: V1 => V1) =
       new Map2(k1, f(v1), k2, f(v2))
-    def foreachKey(f: Any => Unit) = { f(k1); f(k2) }
+    def foreachKey(f: K => Unit) = { f(k1); f(k2) }
   }
 
-  class Map3[-K, +V >: Null] (k1: K, v1: V, k2: K, v2: V, k3: K, v3: V) extends SimpleMap[K, V] {
+  class Map3[K, +V >: Null] (k1: K, v1: V, k2: K, v2: V, k3: K, v3: V) extends SimpleMap[K, V] {
     def apply(k: K) =
       if (k == k1) v1
       else if (k == k2) v2
@@ -70,10 +86,10 @@ object SimpleMap {
       else new Map4(k1, v1, k2, v2, k3, v3, k, v)
     def mapValues[V1 >: V](f: V1 => V1) =
       new Map3(k1, f(v1), k2, f(v2), k3, f(v3))
-    def foreachKey(f: Any => Unit) = { f(k1); f(k2); f(k3) }
+    def foreachKey(f: K => Unit) = { f(k1); f(k2); f(k3) }
   }
 
-  class Map4[-K, +V >: Null] (k1: K, v1: V, k2: K, v2: V, k3: K, v3: V, k4: K, v4: V) extends SimpleMap[K, V] {
+  class Map4[K, +V >: Null] (k1: K, v1: V, k2: K, v2: V, k3: K, v3: V, k4: K, v4: V) extends SimpleMap[K, V] {
     def apply(k: K) =
       if (k == k1) v1
       else if (k == k2) v2
@@ -94,10 +110,10 @@ object SimpleMap {
       else new Map5(k1, v1, k2, v2, k3, v3, k4, v4, k, v)
     def mapValues[V1 >: V](f: V1 => V1) =
       new Map4(k1, f(v1), k2, f(v2), k3, f(v3), k4, f(v4))
-    def foreachKey(f: Any => Unit) = { f(k1); f(k2); f(k3); f(k4) }
+    def foreachKey(f: K => Unit) = { f(k1); f(k2); f(k3); f(k4) }
   }
 
-  class Map5[-K, +V >: Null] (k1: K, v1: V, k2: K, v2: V, k3: K, v3: V, k4: K, v4: V, k5: K, v5: V) extends SimpleMap[K, V] {
+  class Map5[K, +V >: Null] (k1: K, v1: V, k2: K, v2: V, k3: K, v3: V, k4: K, v4: V, k5: K, v5: V) extends SimpleMap[K, V] {
     def apply(k: K) =
       if (k == k1) v1
       else if (k == k2) v2
@@ -121,10 +137,10 @@ object SimpleMap {
       else new MapMore(Map(k1 -> v1, k2 -> v2, k3 -> v3, k4 -> v4, k5 -> v5, k -> v))
     def mapValues[V1 >: V](f: V1 => V1) =
       new Map5(k1, f(v1), k2, f(v2), k3, f(v3), k4, f(v4), k5, f(v5))
-    def foreachKey(f: Any => Unit) = { f(k1); f(k2); f(k3); f(k4); f(k5) }
+    def foreachKey(f: K => Unit) = { f(k1); f(k2); f(k3); f(k4); f(k5) }
   }
 
-  class MapMore[-K, +V >: Null] (m: Map[K, V]) extends SimpleMap[K, V] {
+  class MapMore[K, +V >: Null] (m: Map[K, V]) extends SimpleMap[K, V] {
     def apply(k: K) = m get k match {
       case Some(v) => v
       case None => null
@@ -142,6 +158,6 @@ object SimpleMap {
     override def contains(k: K) = m contains k
     def mapValues[V1 >: V](f: V1 => V1) =
       new MapMore(m mapValues f)
-    def foreachKey(f: Any => Unit) = { m.keysIterator foreach f }
+    def foreachKey(f: K => Unit) = { m.keysIterator foreach f }
   }
 }