runBefore in scripts (#177)

Author: mpollmeier

README.md

@@ -20,28 +20,31 @@ srp
 Prerequisite: jdk11+
 
 ## TOC
+<!-- generated with:
+markdown-toc --maxdepth 3 README.md|tail -n +4 
+-->
 - [Benefits over / comparison with](#benefits-over--comparison-with)
   * [Regular Scala REPL](#regular-scala-repl)
   * [Ammonite](#ammonite)
   * [scala-cli](#scala-cli)
 - [Prerequisite for all of the below: run `sbt stage` or download the latest release](#prerequisite-for-all-of-the-below-run-sbt-stage-or-download-the-latest-release)
-- [REPL](#repl)
+- [Usage](#usage)
   * [run with defaults](#run-with-defaults)
   * [execute code at the start with `--runBefore`](#execute-code-at-the-start-with---runbefore)
-  * [`--predef`: code that is compiled but not executed](#--predef-code-that-is-compiled-but-not-executed)
+  * [`--predef`: add source files to the classpath](#--predef-add-source-files-to-the-classpath)
   * [Operators: Redirect to file, pipe to external command](#operators-redirect-to-file-pipe-to-external-command)
   * [Add dependencies with maven coordinates](#add-dependencies-with-maven-coordinates)
   * [Importing additional script files interactively](#importing-additional-script-files-interactively)
   * [Adding classpath entries](#adding-classpath-entries)
+- [REPL](#repl)
   * [Rendering of output](#rendering-of-output)
   * [Exiting the REPL](#exiting-the-repl)
   * [customize prompt, greeting and exit code](#customize-prompt-greeting-and-exit-code)
   * [Looking up the current terminal width](#looking-up-the-current-terminal-width)
 - [Scripting](#scripting)
   * [Simple "Hello world" script](#simple-hello-world-script)
-  * [Predef file(s) used in script](#predef-files-used-in-script)
-  * [Importing files / scripts](#importing-files--scripts)
-  * [Dependencies](#dependencies)
+  * [Importing other files / scripts with `using file` directive](#importing-other-files--scripts-with-using-file-directive)
+  * [Dependencies with `using dep` directive](#dependencies-with-using-dep-directive)
   * [@main entrypoints](#main-entrypoints)
   * [multiple @main entrypoints](#multiple-main-entrypoints)
   * [named parameters](#named-parameters)
@@ -64,6 +67,7 @@ Prerequisite: jdk11+
 - [Fineprint](#fineprint)
 
 
+
 ## Benefits over / comparison with
 
 ### Regular Scala REPL
@@ -93,7 +97,8 @@ scala-cli wraps and invokes the regular Scala REPL (by default; or optionally Am
 
 ## Prerequisite for all of the below: run `sbt stage` or download the latest release
 
-## REPL
+## Usage
+The below features are all demonstrated using the REPL but also work when running scripts. 
 
 ### run with defaults
 ```bash
@@ -265,6 +270,8 @@ println(new Foo().foo)' > myScript.sc
 ./srp --script myScript.sc
 ```
 
+## REPL
+
 ### Rendering of output
 
 Unlike the stock Scala REPL, srp does _not_ truncate the output by default. You can optionally specify the maxHeight parameter though:
@@ -327,18 +334,7 @@ echo 'println("Hello!")' > test-simple.sc
 cat out.txt # prints 'i was here'
 ```
 
-### Predef file(s) used in script
-```bash
-echo 'val foo = "Hello, predef file"' > test-predef-file.sc
-echo 'println(foo)' > test-predef.sc
-```
-
-```bash
-./srp --script test-predef.sc --predef test-predef-file.sc
-```
-To import multiple scripts, you can specify this parameter multiple times.
-
-### Importing files / scripts
+### Importing other files / scripts with `using file` directive
 ```bash
 echo 'val foo = 42' > foo.sc
 
@@ -348,7 +344,7 @@ println(foo)' > test.sc
 ./srp --script test.sc
 ```
 
-### Dependencies
+### Dependencies with `using dep` directive
 Dependencies can be added via `//> using dep` syntax (like in scala-cli).
 
 ```bash

core/src/main/scala/replpp/scripting/NonForkingScriptRunner.scala

@@ -36,13 +36,11 @@ object NonForkingScriptRunner {
       commandArgs ++ parameterArgs
     }
 
-    if (config.runBefore.nonEmpty)
-      println(s"[WARNING] ScriptingDriver does not support `runBefore` code, the given ${config.runBefore.size} statements will be ignored")
-
     val verboseEnabled = replpp.verboseEnabled(config)
     new ScriptingDriver(
       compilerArgs = replpp.compilerArgs(config) :+ "-nowarn",
       predefFiles = allPredefFiles(config),
+      runBeforeSourceLines = config.runBefore,
       scriptFile = scriptFile,
       scriptArgs = scriptArgs.toArray,
       verbose = verboseEnabled

core/src/main/scala/replpp/scripting/ScriptingDriver.scala

@@ -20,8 +20,13 @@ import scala.util.{Failure, Try}
   * Main difference: we don't (need to) recursively look for main method entry points in the entire classpath,
   * because we have a fixed class and method name that ScriptRunner uses when it embeds the script and predef code.
   * */
-class ScriptingDriver(compilerArgs: Array[String], predefFiles: Seq[Path], scriptFile: Path, scriptArgs: Array[String], verbose: Boolean) {
-  private val wrappingResult = WrapForMainArgs(Files.readString(scriptFile))
+class ScriptingDriver(compilerArgs: Array[String], 
+                      predefFiles: Seq[Path], 
+                      runBeforeSourceLines: Seq[String], 
+                      scriptFile: Path, 
+                      scriptArgs: Array[String], 
+                      verbose: Boolean) {
+  private val wrappingResult = WrapForMainArgs(Files.readString(scriptFile), runBeforeSourceLines)
   private val wrappedScript = Files.createTempFile("wrapped-script", ".sc")
   private val tempFiles = Seq.newBuilder[Path]
   private var executed = false

core/src/main/scala/replpp/scripting/WrapForMainArgs.scala

@@ -7,21 +7,36 @@ object WrapForMainArgs {
   /** linesBeforeWrappedCode: allows us to adjust line numbers in error reporting... */
   case class WrappingResult(fullScript: String, linesBeforeWrappedCode: Int)
 
-  def apply(scriptCode: String): WrappingResult = {
-    var linesBeforeWrappedCode = 0
+  def apply(scriptCode: String, runBeforeAsSourceLines: Seq[String]): WrappingResult = {
+    val runBeforeCode = runBeforeAsSourceLines.mkString("\n")
+
+    val wrapperCodeStart =
+      s"""import replpp.shaded.mainargs
+         |import mainargs.main // intentionally shadow any potentially given @main
+         |
+         |// ScriptingDriver expects an object with a predefined name and a main entrypoint method
+         |object ${ScriptingDriver.MainClassName} {
+         |// runBeforeCode START
+         |$runBeforeCode
+         |// runBeforeCode END
+         |""".stripMargin
+
+    var linesBeforeWrappedCode = 0 // to adjust line number reporting
+
     val mainImpl =
-      if (scriptCode.contains("@main")) {
+      if (scriptCode.contains("@main"))
         scriptCode
-      } else {
-        linesBeforeWrappedCode += 1
+      else {
+        linesBeforeWrappedCode += 1 // because we added the following line _before_ the wrapped script code
         s"""@main def _execMain(): Unit = {
            |$scriptCode
            |}""".stripMargin
       }
 
-    linesBeforeWrappedCode += codeBefore.lines().count().toInt
+    linesBeforeWrappedCode += wrapperCodeStart.lines().count().toInt
+    linesBeforeWrappedCode += 1 // for the line break after $wrapperCodeStart
     val fullScript =
-      s"""$codeBefore
+      s"""$wrapperCodeStart
          |$mainImpl
          |
          |  def ${ScriptingDriver.MainMethodName}(args: Array[String]): Unit = {
@@ -33,11 +48,4 @@ object WrapForMainArgs {
     WrappingResult(fullScript, linesBeforeWrappedCode)
   }
 
-  private val codeBefore =
-    s"""import replpp.shaded.mainargs
-       |import mainargs.main // intentionally shadow any potentially given @main
-       |
-       |// ScriptingDriver expects an object with a predefined name and a main entrypoint method
-       |object ${ScriptingDriver.MainClassName} {""".stripMargin
-
 }

core/src/test/scala/replpp/scripting/ScriptRunnerTests.scala

@@ -66,6 +66,34 @@ class ScriptRunnerTests extends AnyWordSpec with Matchers {
       }.get shouldBe "iwashere-predefFile"
     }
 
+    "runBeforeCode" in {
+      execTest { testOutputPath =>
+        TestSetup(
+          s"""import java.nio.file.*
+             |val string = MaxValue + ";" + fromRunBeforeCode
+             |Files.writeString(Path.of("$testOutputPath"), string)""".stripMargin,
+          adaptConfig = _.copy(runBefore = List(
+            "import Byte.MaxValue",
+            "val fromRunBeforeCode = \"iwashere-runBeforeCode\""
+          ))
+        )
+      }.get shouldBe "127;iwashere-runBeforeCode"
+    }
+
+    "predefFiles and runBeforeCode" in {
+      execTest { testOutputPath =>
+        val predefFile = os.temp("""val bar = "iwashere-predefFile"""").toNIO
+        TestSetup(
+          s"""import java.nio.file.*
+             |val string = MinValue + ";" + bar
+             |Files.writeString(Path.of("$testOutputPath"), string)""".stripMargin,
+          adaptConfig = _.copy(
+            predefFiles = List(predefFile),
+            runBefore = List("import Byte.MinValue"))
+        )
+      }.get shouldBe "-128;iwashere-predefFile"
+    }
+
     "additional dependencies" in {
       execTest { testOutputPath =>
         TestSetup(
@@ -204,7 +232,7 @@ class ScriptRunnerTests extends AnyWordSpec with Matchers {
         // TODO: this isn't the case yet: note: if we intercepted the stdout/stderr, we could/should observe that the error is reported in line 1
       }
 
-      "error is in imported file" in {
+      "error in imported file" in {
         ensureErrors { () =>
           val additionalScript = os.temp()
           os.write.over(additionalScript,
@@ -220,12 +248,12 @@ class ScriptRunnerTests extends AnyWordSpec with Matchers {
         // note: if we intercepted the stdout/stderr, we could/should observe that the error is reported in line 2
       }
 
-      "error is in predef file" in {
+      "error in predef file" in {
         ensureErrors { () =>
           val predefFile = os.temp()
           os.write.over(predefFile,
             s"""val foo = 42
-               |val thisWillNotCompile: Int = "because we need an Int"
+               |val thisWillNotCompile: Int = "because this a String and not an Int"
                |""".stripMargin)
           TestSetup(
             "val bar = 34".stripMargin,
@@ -235,6 +263,27 @@ class ScriptRunnerTests extends AnyWordSpec with Matchers {
         // note: if we intercepted the stdout/stderr, we could/should observe that the error is reported in line 2
       }
 
+      "error in runBeforeCode" in {
+        ensureErrors { () =>
+          TestSetup(
+            "val bar = 34".stripMargin,
+            adaptConfig = _.copy(runBefore = Seq("val thisWillNotCompile: Int = \"because this a String and not an Int\""))
+          )
+        }
+      }
+
+      "error in script with given runBeforeCode" in {
+        ensureErrors { () =>
+          TestSetup(
+            s"""val foo = 42
+               |val thisWillNotCompile: Int = "because this a String and not an Int"
+               |""".stripMargin,
+            adaptConfig = _.copy(runBefore = Seq("val bar = 34"))
+          )
+          // note: if we intercepted the stdout/stderr, we could/should observe that the error is reported in line 2
+        }
+      }
+
     }
   }