Add option for NIR file deserialization to scala-native-p (#8)

* Add option for NIR file deserialization to scala-native-p

* Add simple test for file deserialization

* Address review comments

* Remove repeated iterations

Author: jchyb

cli/src/main/scala/scala/scalanative/cli/ScalaNativeP.scala

@@ -9,6 +9,12 @@ import scala.scalanative.cli.options._
 import scala.scalanative.nir.Global
 import scala.scalanative.build.Config
 import scala.scalanative.linker.ClassLoader
+import java.nio.file.Path
+import scala.scalanative.io.VirtualDirectory
+import scala.scalanative.nir.serialization.deserializeBinary
+import scala.scalanative.nir.Defn
+import scala.annotation.tailrec
+import java.nio.ByteBuffer
 
 object ScalaNativeP extends CaseApp[POptions] {
 
@@ -19,7 +25,10 @@ object ScalaNativeP extends CaseApp[POptions] {
     }
 
     if (args.all.isEmpty) {
-      System.err.println("Required NIR file not specified.")
+      if (options.fromPath)
+        System.err.println("Required NIR file not specified.")
+      else
+        System.err.println("Required class/object not specified.")
       exit(1)
     }
 
@@ -32,29 +41,81 @@ object ScalaNativeP extends CaseApp[POptions] {
       System.err.println(s"Ignoring non existing path: $path")
     }
 
+    if (options.fromPath) printFromFiles(classpath, args.all)
+    else printFromNames(classpath, args.all)
+  }
+
+  private def printFromNames(
+      classpath: List[Path],
+      args: Seq[String]
+  ): Unit = {
     Scope { implicit scope =>
       val classLoader =
         ClassLoader.fromDisk {
           Config.empty.withClassPath(classpath)
         }
 
       for {
-        fileName <- args.all
+        className <- args
       } {
-        classLoader.load(Global.Top(fileName)) match {
-          case Some(defns) =>
-            defns
-              .sortBy(_.name.mangle)
-              .foreach { d =>
-                println(d.show)
-                println()
-              }
-          case None => fail(s"Not found class/object with name `${fileName}`")
+        classLoader.load(Global.Top(className)) match {
+          case Some(defns) => printNIR(defns)
+          case None => fail(s"Not found class/object with name `${className}`")
         }
       }
     }
   }
 
+  private def printFromFiles(
+      classpath: List[Path],
+      args: Seq[String]
+  ): Unit = {
+
+    Scope { implicit scope =>
+      val cp = classpath.toStream.map(VirtualDirectory.real(_))
+      def virtualDirPathMatches(
+          virtualPath: Path,
+          regularPath: Path
+      ): Boolean = {
+        // Paths in jars are always using Unix path denotation
+        val relativeInJar = virtualPath.toString().stripPrefix("/")
+        relativeInJar == regularPath.toString()
+      }
+      @tailrec
+      def findAndRead(
+          classpath: Stream[VirtualDirectory],
+          path: Path
+      ): Option[ByteBuffer] = {
+        classpath match {
+          case Stream.Empty => None
+          case dir #:: tail =>
+            val found = dir.files
+              .find(virtualDirPathMatches(_, path))
+              .map(dir.read(_))
+            if (found.isEmpty) findAndRead(tail, path)
+            else found
+        }
+      }
+      for {
+        fileName <- args
+        path = Paths.get(fileName).normalize()
+        content <- findAndRead(cp, path)
+          .orElse(fail(s"Not found file with name `${fileName}`"))
+      } {
+        val defns = deserializeBinary(content, fileName)
+        printNIR(defns)
+      }
+    }
+  }
+
+  private def printNIR(defns: Seq[Defn]) =
+    defns
+      .sortBy(_.name.mangle)
+      .foreach { d =>
+        println(d.show)
+        println()
+      }
+
   private def fail(msg: String): Nothing = {
     Console.err.println(msg)
     exit(1)

cli/src/main/scala/scala/scalanative/cli/options/POptions.scala

@@ -9,6 +9,10 @@ case class POptions(
     @ExtraName("cp")
     @ValueDescription("<path>")
     classpath: List[String] = "." :: Nil,
+    @HelpMessage(
+      "Instead of passing class/object names, pass NIR file paths."
+    )
+    fromPath: Boolean = false,
     @Recurse
     misc: MiscOptions
 )

cli/src/sbt-test/integration/standalone/test

@@ -9,6 +9,13 @@ $ exists Foo$.nir
 
 -> runScript scala-native-p not.existing.Class
 
+> runScript scala-native-p --from-path Foo.nir
+-> runScript scala-native-p --from-path notExisting.nir
+
+> runExec jar cf inside.jar Foo.class Foo.nir Foo$.class Foo$.nir
+> runScript scala-native-p --cp inside.jar --from-path Foo.nir Foo$.nir
+-> runScript scala-native-p --cp inside.jar --from-path Main$.nir
+
 > runScript scala-native-ld --main Main . -o scala-native-out.exe -v -v
 $ exists scala-native-out.exe
 > runExec ./scala-native-out.exe