Worksheet mode in Dotty IDE

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

@@ -548,6 +548,7 @@ object StdNames {
     val wait_ : N               = "wait"
     val withFilter: N           = "withFilter"
     val withFilterIfRefutable: N = "withFilterIfRefutable$"
+    val WorksheetWrapper: N     = "WorksheetWrapper"
     val wrap: N                 = "wrap"
     val zero: N                 = "zero"
     val zip: N                  = "zip"

compiler/src/dotty/tools/dotc/interactive/Interactive.scala

@@ -265,12 +265,12 @@ object Interactive {
       namedTrees(trees, (include & Include.references) != 0, matchSymbol(_, sym, include))
 
   /** Find named trees with a non-empty position whose name contains `nameSubstring` in `trees`.
-   *
-   *  @param includeReferences  If true, include references and not just definitions
    */
-  def namedTrees(trees: List[SourceTree], includeReferences: Boolean, nameSubstring: String)
-   (implicit ctx: Context): List[SourceTree] =
-    namedTrees(trees, includeReferences, _.show.toString.contains(nameSubstring))
+  def namedTrees(trees: List[SourceTree], nameSubstring: String)
+   (implicit ctx: Context): List[SourceTree] = {
+    val predicate: NameTree => Boolean = _.name.toString.contains(nameSubstring)
+    namedTrees(trees, includeReferences = false, predicate)
+  }
 
   /** Find named trees with a non-empty position satisfying `treePredicate` in `trees`.
    *
@@ -322,7 +322,7 @@ object Interactive {
     val includeLinkedClass = (includes & Include.linkedClass) != 0
     val predicate: NameTree => Boolean = tree =>
       (  tree.pos.isSourceDerived
-      && !tree.symbol.isConstructor
+      && !tree.symbol.isPrimaryConstructor
       && (includeDeclaration || !Interactive.isDefinition(tree))
       && (  Interactive.matchSymbol(tree, symbol, includes)
          || (  includeDeclaration

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -1404,7 +1404,8 @@ object Parsers {
           val (impl, missingBody) = template(emptyConstructor)
           impl.parents match {
             case parent :: Nil if missingBody =>
-              if (parent.isType) ensureApplied(wrapNew(parent)) else parent
+              if (parent.isType) ensureApplied(wrapNew(parent))
+              else parent.withPos(Position(start, in.lastOffset))
             case _ =>
               New(impl.withPos(Position(start, in.lastOffset)))
           }

compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorMessageID.java

@@ -135,7 +135,8 @@ public enum ErrorMessageID {
     CaseClassCannotExtendEnumID,
     ValueClassParameterMayNotBeCallByNameID,
     NotAnExtractorID,
-    MemberWithSameNameAsStaticID
+    MemberWithSameNameAsStaticID,
+    PureExpressionInStatementPositionID
     ;
 
     public int errorNumber() {

compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala

@@ -2139,4 +2139,14 @@ object messages {
     override def kind: String = "Syntax"
     override def explanation: String = ""
   }
+
+  case class PureExpressionInStatementPosition(stat: untpd.Tree, exprOwner: Symbol)(implicit ctx: Context)
+    extends Message(PureExpressionInStatementPositionID) {
+
+    val kind = "Potential Issue"
+    val msg = "a pure expression does nothing in statement position; you may be omitting necessary parentheses"
+    val explanation =
+      hl"""The pure expression `$stat` doesn't have any side effect and its result is not assigned elsewhere.
+          |It can be removed without changing the semantics of the program. This may indicate an error.""".stripMargin
+  }
 }

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -2013,7 +2013,7 @@ class Typer extends Namer
         val stat1 = typed(stat)(ctx.exprContext(stat, exprOwner))
         if (!ctx.isAfterTyper && isPureExpr(stat1) &&
             !stat1.tpe.isRef(defn.UnitClass) && !isSelfOrSuperConstrCall(stat1))
-          ctx.warning(em"a pure expression does nothing in statement position", stat.pos)
+          ctx.warning(PureExpressionInStatementPosition(stat, exprOwner), stat.pos)
         buf += stat1
         traverse(rest)
       case nil =>

compiler/src/dotty/tools/repl/JLineTerminal.scala

@@ -13,12 +13,13 @@ import org.jline.reader.impl.history.DefaultHistory
 import org.jline.terminal.TerminalBuilder
 import org.jline.utils.AttributedString
 
-final class JLineTerminal extends java.io.Closeable {
+final class JLineTerminal(needsTerminal: Boolean) extends java.io.Closeable {
   // import java.util.logging.{Logger, Level}
   // Logger.getLogger("org.jline").setLevel(Level.FINEST)
 
-  private val terminal = TerminalBuilder.builder()
-    .dumb(false) // fail early if not able to create a terminal
+  private val terminal =
+    TerminalBuilder.builder()
+    .dumb(!needsTerminal) // fail early if we need a terminal and can't create one
     .build()
   private val history = new DefaultHistory
 

compiler/src/dotty/tools/repl/Main.scala

@@ -3,5 +3,10 @@ package dotty.tools.repl
 /** Main entry point to the REPL */
 object Main {
   def main(args: Array[String]): Unit =
-    new ReplDriver(args).runUntilQuit()
+    new ReplDriver(args).runUntilQuit(needsTerminal = true)
+}
+
+object WorksheetMain {
+  def main(args: Array[String]): Unit =
+    new ReplDriver(args).runUntilQuit(needsTerminal = false)
 }

compiler/src/dotty/tools/repl/ReplDriver.scala

@@ -102,8 +102,8 @@ class ReplDriver(settings: Array[String],
    *  observable outside of the CLI, for this reason, most helper methods are
    *  `protected final` to facilitate testing.
    */
-  final def runUntilQuit(initialState: State = initialState): State = {
-    val terminal = new JLineTerminal()
+  final def runUntilQuit(needsTerminal: Boolean, initialState: State = initialState): State = {
+    val terminal = new JLineTerminal(needsTerminal)
 
     /** Blockingly read a line, getting back a parse result */
     def readLine(state: State): ParseResult = {
@@ -285,7 +285,12 @@ class ReplDriver(settings: Array[String],
       .foreach { sym =>
         // FIXME syntax highlighting on comment is currently not working
         // out.println(SyntaxHighlighting.highlight("// defined " + sym.showUser))
-        out.println(SyntaxHighlighting.CommentColor + "// defined " + sym.showUser + SyntaxHighlighting.NoColor)
+        val message = "// defined " + sym.showUser
+        if (ctx.settings.color.value != "never") {
+          println(SyntaxHighlighting.CommentColor + message + SyntaxHighlighting.NoColor)
+        } else {
+          println(message)
+        }
       }
 
 

compiler/test-resources/repl/errmsgs

@@ -25,9 +25,9 @@ scala> val z: (List[String], List[Int]) = (List(1), List("a"))
   |
 scala> val a: Inv[String] = new Inv(new Inv(1))
 1 | val a: Inv[String] = new Inv(new Inv(1))
-  |                                  ^^^^^^
-  |                                  found:    Inv[Int]
-  |                                  required: String
+  |                              ^^^^^^^^^^
+  |                              found:    Inv[Int]
+  |                              required: String
   |
 scala> val b: Inv[String] = new Inv(1)
 1 | val b: Inv[String] = new Inv(1)