Generalize buffering for Name construction from substring

Author: liufengyun

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

@@ -89,16 +89,6 @@ object Contexts {
   inline def withoutMode[T](mode: Mode)(inline op: Context ?=> T)(using ctx: Context): T =
     inMode(ctx.mode &~ mode)(op)
 
-  private[dotc] inline def withNameBuffer(inline op: Array[Char] => Int)(using ctx: Context): Names.TermName = {
-    val base = ctx.base
-    var len = op(base.nameCharBuffer)
-    while(len == -1) {
-      base.nameCharBuffer = new Array[Char](base.nameCharBuffer.length * 2)
-      len = op(base.nameCharBuffer)
-    }
-    Names.termName(base.nameCharBuffer, 0, len)
-  }
-
   /** A context is passed basically everywhere in dotc.
    *  This is convenient but carries the risk of captured contexts in
    *  objects that turn into space leaks. To combat this risk, here are some

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

@@ -644,6 +644,19 @@ object Names {
   /** Create a type name from a string, without encoding operators */
   def typeName(s: String): TypeName = typeName(s.toCharArray, 0, s.length)
 
+  def termName(s: String, from: Int, len: Int)(using ctx: Contexts.Context): TermName = {
+    val base = ctx.base
+
+    while (len > base.nameCharBuffer.length)
+      base.nameCharBuffer = new Array[Char](base.nameCharBuffer.length * 2)
+
+    s.getChars(from, from + len, base.nameCharBuffer, 0)
+    termName(base.nameCharBuffer, 0, len)
+  }
+
+  def typeName(s: String, from: Int, len: Int)(using ctx: Contexts.Context): TypeName =
+    termName(s, from, len).toTypeName
+
   table(0) = new SimpleName(-1, 0, null)
 
   /** The term name represented by the empty string */

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

@@ -205,7 +205,7 @@ object SymbolLoaders {
     src.lastModified >= bin.lastModified
 
   private def nameOf(classRep: ClassRepresentation)(using Context): TermName =
-    withNameBuffer(classRep.nameChars)
+    termName(classRep.fileName, 0, classRep.nameLength)
 
   /** Load contents of a package
    */

compiler/src/dotty/tools/io/ClassPath.scala

@@ -175,16 +175,13 @@ trait ClassRepresentation {
   def binary: Option[AbstractFile]
   def source: Option[AbstractFile]
 
-  /** Low level way to extract the entry name without allocation. */
-  final def nameChars(buffer: Array[Char]): Int = {
+  /** returns the length of `name` by stripping the extension of `fileName`
+   *
+   *  Used to avoid creating String instance of `name`.
+   */
+  final def nameLength: Int = {
     val ix = fileName.lastIndexOf('.')
-    val nameLength = if (ix < 0) fileName.length else ix
-    if (nameLength > buffer.length)
-      -1
-    else {
-      fileName.getChars(0, nameLength, buffer, 0)
-      nameLength
-    }
+    if (ix < 0) fileName.length else ix
   }
 }