From 7dc655155019f25ae087f2599c82b59694f968d1 Mon Sep 17 00:00:00 2001
From: Jakob Odersky <jakob@odersky.com>
Date: Mon, 3 Jul 2017 20:08:36 -0700
Subject: Add javah plugin

---
 plugins/javah/Javah.scala       | 97 +++++++++++++++++++++++++++++++++++++++++
 plugins/javah/build/build.scala |  9 ++++
 stage2/plugins.scala            |  1 +
 3 files changed, 107 insertions(+)
 create mode 100644 plugins/javah/Javah.scala
 create mode 100644 plugins/javah/build/build.scala

diff --git a/plugins/javah/Javah.scala b/plugins/javah/Javah.scala
new file mode 100644
index 0000000..cc8aec1
--- /dev/null
+++ b/plugins/javah/Javah.scala
@@ -0,0 +1,97 @@
+package cbt
+
+import java.io.{ File, FileInputStream, Closeable }
+import java.nio.file._
+import scala.collection.JavaConverters._
+import scala.collection.mutable.{ HashSet }
+import scala.sys.process._
+
+import org.objectweb.asm.{ ClassReader, ClassVisitor, MethodVisitor, Opcodes }
+
+trait Javah extends BaseBuild {
+
+  def javah = Javah.apply(lib, println _).config(
+    (target / "include").toPath,
+    exportedClasspath.files ++ dependencyClasspath.files,
+    exportedClasspath.files
+      .flatMap(file => Files.walk(file.toPath).iterator().asScala.toSeq)
+      .toSet
+      .filter(Files.isRegularFile(_))
+      .flatMap(Javah.findNativeClasses)
+  )
+
+}
+
+object Javah {
+
+  case class apply(lib: Lib, log: (String) => Unit) {
+    case class config(target: Path, classpath: Seq[File], nativeClasses: Set[String]) {
+      def apply: Set[String] = {
+        val cp = classpath.mkString(sys.props("path.separator"))
+        if (!Files.exists(target)) {
+          log("creating file")
+        }
+        if (!nativeClasses.isEmpty) {
+          log(s"headers will be generated in $target")
+        }
+        for (clazz <- nativeClasses) yield {
+          log(s"generating header for $clazz")
+          val parts = Seq(
+            "javah",
+            "-d", target.toString,
+            "-classpath", cp,
+            clazz
+          )
+          val cmd = parts.mkString(" ")
+          Process(cmd).!!
+        }
+      }
+    }
+  }
+
+
+  private class NativeFinder extends ClassVisitor(Opcodes.ASM5) {
+
+    // classes found to contain at least one @native def
+    val _nativeClasses = new HashSet[String]
+    def nativeClasses = _nativeClasses.toSet
+
+    private var fullyQualifiedName: String = ""
+
+    override def visit(version: Int, access: Int, name: String, signature: String,
+      superName: String, interfaces: Array[String]): Unit = {
+      fullyQualifiedName = name.replaceAll("/", ".")
+    }
+
+    override def visitMethod(access: Int, name: String, desc: String,
+      signature: String, exceptions: Array[String]): MethodVisitor = {
+
+      val isNative = (access & Opcodes.ACC_NATIVE) != 0
+
+      if (isNative) {
+        _nativeClasses += fullyQualifiedName
+      }
+
+      null //return null, do not visit method further
+    }
+
+  }
+
+  /** Finds classes containing native implementations.
+    * @param classFile java class file from which classes are read
+    * @return all fully qualified names of classes that contain at least one member annotated
+    * with @native
+    */
+  def findNativeClasses(classFile: Path): Set[String]  = {
+    val in = Files.newInputStream(classFile)
+    try {
+      val reader = new ClassReader(in)
+      val finder = new NativeFinder
+      reader.accept(finder, 0)
+      finder.nativeClasses
+    } finally {
+      in.close()
+    }
+  }
+
+}
diff --git a/plugins/javah/build/build.scala b/plugins/javah/build/build.scala
new file mode 100644
index 0000000..64e25eb
--- /dev/null
+++ b/plugins/javah/build/build.scala
@@ -0,0 +1,9 @@
+package javah_build
+
+import cbt._
+
+class Build(val context: Context) extends Plugin {
+  override def dependencies = super.dependencies ++ Resolver(mavenCentral).bind(
+    MavenDependency("org.ow2.asm", "asm", "5.0.4")
+  )
+}
diff --git a/stage2/plugins.scala b/stage2/plugins.scala
index ea1aa74..3efc1d7 100644
--- a/stage2/plugins.scala
+++ b/stage2/plugins.scala
@@ -7,6 +7,7 @@ class plugins( context: Context, scalaVersion: String ) {
     ),
     None
   )
+  final lazy val javah = plugin( "javah" )
   final lazy val googleJavaFormat = plugin( "google-java-format" )
   final lazy val proguard = plugin( "proguard" )
   final lazy val sbtLayout = plugin( "sbt_layout" )
-- 
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