Flehsed out constraints, with more efficient maps.

1 files changed, 125 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/util/SimpleMap.scala b/src/dotty/tools/dotc/util/SimpleMap.scala
new file mode 100644
index 000000000..f54ae8022
--- /dev/null
+++ b/src/dotty/tools/dotc/util/SimpleMap.scala
@@ -0,0 +1,125 @@
+package dotty.tools.dotc.util
+
+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
+}
+
+object SimpleMap {
+
+  object Empty 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)
+  }
+
+  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
+      else this
+    def updated[V1 >: V](k: K, v: V1) =
+      if (k == k1) new Map1(k, v)
+      else new Map2(k1, v1, 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
+      else null
+    def remove(k: K) =
+      if (k == k1) new Map1(k2, v2)
+      else if (k == k2) new Map1(k1, v1)
+      else this
+    def updated[V1 >: V](k: K, v: V1) =
+      if (k == k1) new Map2(k, v, k2, v2)
+      else if (k == k2) new Map2(k1, v1, k, v)
+      else new Map3(k1, v1, k2, v2, 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
+      else if (k == k3) v3
+      else null
+    def remove(k: K) =
+      if (k == k1) new Map2(k2, v2, k3, v3)
+      else if (k == k2) new Map2(k1, v1, k3, v3)
+      else if (k == k3) new Map2(k1, v1, k2, v2)
+      else this
+    def updated[V1 >: V](k: K, v: V1) =
+      if (k == k1) new Map3(k, v, k2, v2, k3, v3)
+      else if (k == k2) new Map3(k1, v1, k, v, k3, v3)
+      else if (k == k3) new Map3(k1, v1, k2, v2, k, v)
+      else new Map4(k1, v1, k2, v2, k3, v3, 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
+      else if (k == k3) v3
+      else if (k == k4) v4
+      else null
+    def remove(k: K) =
+      if (k == k1) new Map3(k2, v2, k3, v3, k4, v4)
+      else if (k == k2) new Map3(k1, v1, k3, v3, k4, v4)
+      else if (k == k3) new Map3(k1, v1, k2, v2, k4, v4)
+      else if (k == k4) new Map3(k1, v1, k2, v2, k3, v3)
+      else this
+    def updated[V1 >: V](k: K, v: V1) =
+      if (k == k1) new Map4(k, v, k2, v2, k3, v3, k4, v4)
+      else if (k == k2) new Map4(k1, v1, k, v, k3, v3, k4, v4)
+      else if (k == k3) new Map4(k1, v1, k2, v2, k, v, k4, v4)
+      else if (k == k4) new Map4(k1, v1, k2, v2, k3, v3, k, v)
+      else new Map5(k1, v1, k2, v2, k3, v3, k4, v4, 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
+      else if (k == k3) v3
+      else if (k == k4) v4
+      else if (k == k5) v5
+      else null
+    def remove(k: K) =
+      if (k == k1) new Map4(k2, v2, k3, v3, k4, v4, k5, v5)
+      else if (k == k2) new Map4(k1, v1, k3, v3, k4, v4, k5, v5)
+      else if (k == k3) new Map4(k1, v1, k2, v2, k4, v4, k5, v5)
+      else if (k == k4) new Map4(k1, v1, k2, v2, k3, v3, k5, v5)
+      else if (k == k5) new Map4(k1, v1, k2, v2, k3, v3, k4, v4)
+      else this
+    def updated[V1 >: V](k: K, v: V1) =
+      if (k == k1) new Map5(k, v, k2, v2, k3, v3, k4, v4, k5, v5)
+      else if (k == k2) new Map5(k1, v1, k, v, k3, v3, k4, v4, k5, v5)
+      else if (k == k3) new Map5(k1, v1, k2, v2, k, v, k4, v4, k5, v5)
+      else if (k == k4) new Map5(k1, v1, k2, v2, k3, v3, k, v, k5, v5)
+      else if (k == k5) new Map5(k1, v1, k2, v2, k3, v3, k4, v4, k, v)
+      else new MapMore(Map(k1 -> v1, k2 -> v2, k3 -> v3, k4 -> v4, k5 -> v5, 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
+    }
+    def remove(k: K) = {
+      val m1 = m - k
+      if (m1.size > 5) new MapMore(m1)
+      else {
+        val List((k1, v1), (k2, v2), (k3, v3), (k4, v4), (k5, v5)) = m1.toList
+        new Map5(k1, v1, k2, v2, k3, v3, k4, v4, k5, v5)
+      }
+    }
+    def updated[V1 >: V](k: K, v: V1) =
+      new MapMore(m.updated(k, v))
+    override def contains(k: K) = m contains k
+  }
+}