add -e <expression> eval to command line

Author: philwalk

compiler/src/dotty/tools/MainGenericRunner.scala

@@ -81,6 +81,9 @@ case class Settings(
   def withSave: Settings =
     this.copy(save = true)
 
+  def noSave: Settings =
+    this.copy(save = false)
+
   def withModeShouldBePossibleRun: Settings =
     this.copy(modeShouldBePossibleRun = true)
 
@@ -144,6 +147,13 @@ object MainGenericRunner {
       process(remainingArgs, settings)
     case (o @ colorOption(_*)) :: tail =>
       process(tail, settings.withScalaArgs(o))
+    case "-e" :: expression :: tail =>
+      val tempScript = writeFile(s"@main def main(args: String *): Unit =\n  ${expression}")
+      settings
+        .withExecuteMode(ExecuteMode.Script)
+        .withTargetScript(tempScript)
+        .withScriptArgs(tail*)
+        .noSave // useless
     case arg :: tail =>
       val line = Try(Source.fromFile(arg).getLines.toList).toOption.flatMap(_.headOption)
       lazy val hasScalaHashbang = { val s = line.getOrElse("") ; s.startsWith("#!") && s.contains("scala") }
@@ -156,6 +166,7 @@ object MainGenericRunner {
         val newSettings = if arg.startsWith("-") then settings else settings.withPossibleEntryPaths(arg).withModeShouldBePossibleRun
         process(tail, newSettings.withResidualArgs(arg))
 
+      
   def main(args: Array[String]): Unit =
     val scalaOpts = envOrNone("SCALA_OPTS").toArray.flatMap(_.split(" ")).filter(_.nonEmpty)
     val allArgs = scalaOpts ++ args
@@ -244,4 +255,11 @@ object MainGenericRunner {
     e.foreach(_.printStackTrace())
     !isFailure
   }
+  def writeFile(contents: String): String = {
+    val file = Files.createTempFile("exec", ".scala")
+    file.toFile.deleteOnExit()
+    Files.write(file, contents.getBytes)
+    file.toString.replace('\\', '/')
+  }
+
 }

compiler/test/dotty/tools/scripting/BashScriptsTests.scala

@@ -188,3 +188,18 @@ class BashScriptsTests:
       if valid then printf(s"\n===> success: classpath begins with %s, as reported by [%s]\n", workingDirectory, scriptFile.getName)
       assert(valid, s"script ${scriptFile.absPath} did not report valid java.class.path first entry")
 
+  /*
+   * verify -e println("yo!") works.
+   */
+  @Test def verifyCommandLineExpression =
+    printf("===> verify -e <expression> is properly handled by `dist/bin/scala`\n")
+    val expected = "9"
+    val expression = s"println(3*3)"
+    val cmd = s"bin/scala -e $expression"
+    val (validTest, exitCode, stdout, stderr) = bashCommand(s"""bin/scala -e '$expression'""")
+    val result = stdout.filter(_.nonEmpty).mkString("")
+    printf("stdout: %s\n", result)
+    printf("stderr: %s\n", stderr.mkString("\n","\n",""))
+    if verifyValid(validTest) then
+      assert(result.contains(expected), s"expression [$expression] did not send [$expected] to stdout")
+