Polish map and set API in dotc.util

 - Rename Map to MutableMap, in order to avoid confusion with the
   default immutable map
 - Rename Set to MutableSet
 - Rename `apply` to `lookup` in LinearMap
 - Drop >: Null lower bound for keys

Author: odersky

compiler/src/dotty/tools/dotc/Run.scala

@@ -14,7 +14,7 @@ import io.{AbstractFile, PlainFile}
 import Phases.unfusedPhases
 
 import scala.io.Codec
-import util.{Set => _, _}
+import util._
 import reporting.Reporter
 import rewrites.Rewrites
 import java.io.{BufferedWriter, OutputStreamWriter}

compiler/src/dotty/tools/dotc/core/Names.scala

@@ -185,7 +185,7 @@ object Names {
     private var derivedNames: LinearMap[NameInfo, DerivedName] = LinearMap.Empty
 
     private def add(info: NameInfo): TermName = synchronized {
-      derivedNames(info) match
+      derivedNames.lookup(info) match
         case null =>
           val derivedName = new DerivedName(this, info)
           derivedNames = derivedNames.updated(info, derivedName)

compiler/src/dotty/tools/dotc/util/GenericHashMap.scala

@@ -22,9 +22,9 @@ object GenericHashMap:
  *                           However, a table of size up to DenseLimit will be re-sized only
  *                           once the number of elements reaches the table's size.
  */
-abstract class GenericHashMap[Key >: Null <: AnyRef, Value >: Null <: AnyRef]
+abstract class GenericHashMap[Key <: AnyRef, Value >: Null <: AnyRef]
     (protected val initialCapacity: Int = 8,
-     protected val capacityMultiple: Int = 3) extends Map[Key, Value]:
+     protected val capacityMultiple: Int = 3) extends MutableMap[Key, Value]:
   import GenericHashMap.DenseLimit
 
   protected var used: Int = _

compiler/src/dotty/tools/dotc/util/HashMap.scala

@@ -3,7 +3,7 @@ package dotty.tools.dotc.util
 /** A specialized implementation of GenericHashMap with standard hashCode and equals
  *  as comparison
  */
-class HashMap[Key >: Null <: AnyRef, Value >: Null <: AnyRef]
+class HashMap[Key <: AnyRef, Value >: Null <: AnyRef]
     (initialCapacity: Int = 8, capacityMultiple: Int = 3)
 extends GenericHashMap[Key, Value](initialCapacity, capacityMultiple):
   import GenericHashMap.DenseLimit

compiler/src/dotty/tools/dotc/util/HashSet.scala

@@ -2,7 +2,7 @@ package dotty.tools.dotc.util
 
 /** A hash set that allows some privileged protected access to its internals
  */
-class HashSet[T >: Null <: AnyRef](powerOfTwoInitialCapacity: Int, loadFactor: Float = 0.25f) extends Set[T] {
+class HashSet[T >: Null <: AnyRef](powerOfTwoInitialCapacity: Int = 16, loadFactor: Float = 0.25f) extends MutableSet[T] {
   private var used: Int = _
   private var limit: Int = _
   private var table: Array[AnyRef] = _

compiler/src/dotty/tools/dotc/util/IdentityHashMap.scala

@@ -3,7 +3,7 @@ package dotty.tools.dotc.util
 /** A specialized implementation of GenericHashMap with identity hash and `eq`
  *  as comparison
  */
-class IdentityHashMap[Key >: Null <: AnyRef, Value >: Null <: AnyRef]
+class IdentityHashMap[Key <: AnyRef, Value >: Null <: AnyRef]
     (initialCapacity: Int = 8, capacityMultiple: Int = 3)
 extends GenericHashMap[Key, Value](initialCapacity, capacityMultiple):
   import GenericHashMap.DenseLimit

compiler/src/dotty/tools/dotc/util/LinearMap.scala

@@ -17,23 +17,23 @@ object LinearMap:
 
   extension [K <: AnyRef, V >: Null <: AnyRef](m: LinearMap[K, V]):
 
-    def apply(key: K): V /*| Null*/ = m match
+    def lookup(key: K): V /*| Null*/ = m match
       case m: immutable.Map[K, V] @unchecked =>
         if m.contains(key) then m(key) else null
       case m: HashMap[K, V] @unchecked =>
-        m.get(key)
+        m.lookup(key)
 
     def updated(key: K, value: V): LinearMap[K, V] = m match
       case m: immutable.Map[K, V] @unchecked =>
         if m.size < 4 then
           m.updated(key, value)
         else
           val m1 = HashMap[K, V]()
-          m.foreach(m1.put(_, _))
-          m1.put(key, value)
+          m.foreach(m1(_) = _)
+          m1(key) = value
           m1
       case m: HashMap[K, V] @unchecked =>
-        m.put(key, value)
+        m(key) = value
         m
 
     def size = m match

compiler/src/dotty/tools/dotc/util/Map.scala renamed to compiler/src/dotty/tools/dotc/util/MutableMap.scala

@@ -2,7 +2,7 @@ package dotty.tools.dotc.util
 
 /** A common class for lightweight mutable maps.
  */
-abstract class Map[Key >: Null <: AnyRef, Value >: Null <: AnyRef]:
+abstract class MutableMap[Key <: AnyRef, Value >: Null <: AnyRef]:
 
   def lookup(x: Key): Value /* | Null */
 
@@ -17,3 +17,4 @@ abstract class Map[Key >: Null <: AnyRef, Value >: Null <: AnyRef]:
   def iterator: Iterator[(Key, Value)]
 
   def get(x: Key): Option[Value] = Option(lookup(x))
+

compiler/src/dotty/tools/dotc/util/Set.scala renamed to compiler/src/dotty/tools/dotc/util/MutableSet.scala

@@ -1,8 +1,8 @@
 package dotty.tools.dotc.util
 
-/** A common class for lightweight sets.
+/** A common class for lightweight mutable sets.
  */
-abstract class Set[T >: Null] {
+abstract class MutableSet[T >: Null] {
 
   def findEntry(x: T): T
 

language-server/src/dotty/tools/languageserver/DottyLanguageServer.scala

@@ -23,7 +23,7 @@ import Comments._, Constants._, Contexts._, Flags._, Names._, NameOps._, Symbols
 import classpath.ClassPathEntries
 import reporting._
 import typer.Typer
-import util.{Set => _, _}
+import util._
 import interactive._, interactive.InteractiveDriver._
 import decompiler.IDEDecompilerDriver
 import Interactive.Include