Add support for partially-shared src dirs

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/build.sbt

@@ -0,0 +1,5 @@
+import sbtcrossproject.{crossProject, CrossType}
+
+lazy val foo = crossProject(JVMPlatform, JSPlatform, NativePlatform)
+  .settings(scalaVersion := "2.11.11")
+  .jsSettings(scalaJSUseMainModuleInitializer := true)

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/foo/js-jvm/src/main/scala/JSOrJVM.scala

@@ -0,0 +1,3 @@
+object JSOrJVM {
+  def check = true
+}

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/foo/js-native/src/main/scala/JSOrNative.scala

@@ -0,0 +1,3 @@
+object JSOrNative {
+  def check = true
+}

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/foo/js/src/main/scala/JVMOrNative.scala

@@ -0,0 +1,3 @@
+object JVMOrNative {
+  def check = false
+}

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/foo/js/src/main/scala/Platform.scala

@@ -0,0 +1,5 @@
+object Platform {
+  def isJVM    = false
+  def isJS     = true
+  def isNative = false
+}

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/foo/jvm-native/src/main/scala/JVMOrNative.scala

@@ -0,0 +1,3 @@
+object JVMOrNative {
+  def check = true
+}

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/foo/jvm/src/main/scala/JSOrNative.scala

@@ -0,0 +1,3 @@
+object JSOrNative {
+  def check = false
+}

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/foo/jvm/src/main/scala/Platform.scala

@@ -0,0 +1,5 @@
+object Platform {
+  def isJVM    = true
+  def isJS     = false
+  def isNative = false
+}

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/foo/native/src/main/scala/JSOrJVM.scala

@@ -0,0 +1,3 @@
+object JSOrJVM {
+  def check = false
+}

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/foo/native/src/main/scala/Platform.scala

@@ -0,0 +1,5 @@
+object Platform {
+  def isJVM    = false
+  def isJS     = false
+  def isNative = true
+}

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/foo/shared/src/main/scala/Foo.scala

@@ -0,0 +1,13 @@
+import Platform._
+object Foo {
+  def main(args: Array[String]): Unit = {
+    assert(List(isJVM, isJS, isNative).count(identity) == 1)
+
+    if (isJVM)
+      assert(JSOrJVM.check && JVMOrNative.check && !JSOrNative.check)
+    if (isJS)
+      assert(JSOrJVM.check && !JVMOrNative.check && JSOrNative.check)
+    if (isNative)
+      assert(!JSOrJVM.check && JVMOrNative.check && JSOrNative.check)
+  }
+}

sbt-crossproject-test/src/sbt-test/new-api/partially-shared-sources/test

@@ -0,0 +1,3 @@
+> fooJVM/run
+> fooJS/run
+> fooNative/run 

sbt-crossproject/src/main/scala/sbtcrossproject/CrossProject.scala

@@ -4,6 +4,9 @@ import sbtcrossproject._
 
 import scala.language.implicitConversions
 
+import scala.collection.immutable.HashMap
+import scala.collection.immutable.ListSet
+
 import sbt._
 import Keys._
 
@@ -202,16 +205,17 @@ object CrossProject {
             ).settings(
               CrossPlugin.autoImport.crossProjectPlatform := platform,
               name := id, // #80
-              sharedSrc,
-              sharedResources
+              sharedSrc(platform),
+              sharedResources(platform)
             )
           )
         }.toMap
 
       new CrossProject(id, crossType, projects)
     }
 
-    private def sharedSrcSettings(crossType: CrossType): Seq[Setting[_]] = {
+    private def sharedSrcSettings(
+        crossType: CrossType): Map[Platform, Seq[Setting[_]]] = {
       def makeCrossSources(sharedSrcDir: Option[File],
                            scalaBinaryVersion: String,
                            cross: Boolean): Seq[File] = {
@@ -234,30 +238,89 @@ object CrossProject {
         }
       }
 
-      Seq(
-        unmanagedSourceDirectories in Compile ++= {
-          makeCrossSources(crossType.sharedSrcDir(baseDirectory.value, "main"),
-                           scalaBinaryVersion.value,
-                           crossPaths.value)
-        },
-        unmanagedSourceDirectories in Test ++= {
-          makeCrossSources(crossType.sharedSrcDir(baseDirectory.value, "test"),
-                           scalaBinaryVersion.value,
-                           crossPaths.value)
+      def makeSharedSettings(
+          key: SettingKey[Seq[File]],
+          config: String): Seq[(Platform, Seq[Setting[_]])] = {
+        val partiallyShared = makePartiallySharedSettings(platforms) {
+          platformSubset =>
+            Seq(
+              key ++= makeCrossSources(
+                crossType.partiallySharedSrcDir(baseDirectory.value,
+                                                platformSubset,
+                                                config),
+                scalaBinaryVersion.value,
+                crossPaths.value)
+            )
         }
-      )
+
+        val shared = Seq(
+          key ++= makeCrossSources(
+            crossType.sharedSrcDir(baseDirectory.value, config),
+            scalaBinaryVersion.value,
+            crossPaths.value)
+        )
+
+        partiallyShared ++ platforms.map(_ -> shared) // add shared to each platform
+      }
+
+      val compileSettings =
+        makeSharedSettings(unmanagedSourceDirectories in Compile, "main")
+      val testSettings =
+        makeSharedSettings(unmanagedSourceDirectories in Test, "test")
+
+      (compileSettings ++ testSettings) // group-reduce the settings per-platform
+        .groupBy(_._1)
+        .map(kv => kv._1 -> kv._2.flatMap(_._2))
     }
 
     private def sharedResourcesSettings(
-        crossType: CrossType): Seq[Setting[_]] = {
-      Seq(
-        unmanagedResourceDirectories in Compile ++= {
-          crossType.sharedResourcesDir(baseDirectory.value, "main")
-        },
-        unmanagedResourceDirectories in Test ++= {
-          crossType.sharedResourcesDir(baseDirectory.value, "test")
+        crossType: CrossType): Map[Platform, Seq[Setting[_]]] = {
+      def makeSharedSettings(
+          key: SettingKey[Seq[File]],
+          config: String): Seq[(Platform, Seq[Setting[_]])] = {
+        val partiallyShared = makePartiallySharedSettings(platforms) {
+          platformSubset =>
+            Seq(
+              key ++= crossType
+                .partiallySharedResourcesDir(baseDirectory.value,
+                                             platformSubset,
+                                             config)
+                .toSeq
+            )
+        }
+
+        val shared = Seq(
+          key ++= crossType
+            .sharedResourcesDir(baseDirectory.value, config)
+            .toSeq
+        )
+
+        partiallyShared ++ platforms.map(_ -> shared) // add shared to each platform
+      }
+
+      val compileSettings =
+        makeSharedSettings(unmanagedResourceDirectories in Compile, "main")
+      val testSettings =
+        makeSharedSettings(unmanagedResourceDirectories in Test, "test")
+
+      (compileSettings ++ testSettings) // group-reduce the settings per-platform
+        .groupBy(_._1)
+        .map(kv => kv._1 -> kv._2.flatMap(_._2))
+    }
+
+    private def makePartiallySharedSettings(platforms: Seq[Platform])(
+        mkSettings: Seq[Platform] => Seq[Setting[_]])
+      : Seq[(Platform, Seq[Setting[_]])] = {
+      platforms.toSet
+        .subsets()
+        .filter(_.size > 1) // skip the empty+singleton subsets
+        .filterNot(_.size == platforms.size) // skip the all-platform subset
+        .toSeq
+        .map(_.toSeq.sortBy(_.identifier)) // use a consistent ordering
+        .flatMap { platformSubset => // make the settings for this subset of platforms
+          val settings = mkSettings(platformSubset)
+          platformSubset.map(_ -> settings).toMap
         }
-      )
     }
 
   }

sbt-crossproject/src/main/scala/sbtcrossproject/CrossType.scala

@@ -37,13 +37,32 @@ abstract class CrossType {
    */
   def sharedSrcDir(projectBase: File, conf: String): Option[File]
 
+  /** The location of a partially shared source directory (if it exists)
+   *  @param projectBase the base directory of a (true sbt) Project
+   *  @param platforms non-empty seq of JSPlatform, JVMPlatform, NativePlatform, ...
+   *  @param conf name of sub-directory for the configuration (typically "main"
+   *      or "test")
+   */
+  def partiallySharedSrcDir(projectBase: File,
+                            platforms: Seq[Platform],
+                            conf: String): Option[File] = None
+
   /** The location of a shared resources directory (if it exists)
    *  @param projectBase the base directory of a (true sbt) Project
    *  @param conf name of sub-directory for the configuration (typically "main"
    *      or "test")
    */
   def sharedResourcesDir(projectBase: File, conf: String): Option[File] = None
 
+  /** The location of a partially shared resources directory (if it exists)
+   *  @param projectBase the base directory of a (true sbt) Project
+   *  @param conf name of sub-directory for the configuration (typically "main"
+   *      or "test")
+   */
+  def partiallySharedResourcesDir(projectBase: File,
+                                  platforms: Seq[Platform],
+                                  conf: String): Option[File] = None
+
 }
 
 object CrossType {
@@ -69,9 +88,26 @@ object CrossType {
     def sharedSrcDir(projectBase: File, conf: String): Option[File] =
       Some(projectBase.getParentFile / "shared" / "src" / conf / "scala")
 
+    override def partiallySharedSrcDir(projectBase: File,
+                                       platforms: Seq[Platform],
+                                       conf: String): Option[File] = {
+      val dir = platforms.map(_.identifier).mkString("-")
+      Some(projectBase.getParentFile / dir / "src" / conf / "scala")
+    }
+
     override def sharedResourcesDir(projectBase: File,
                                     conf: String): Option[File] =
       Some(projectBase.getParentFile / "shared" / "src" / conf / "resources")
+
+    override def partiallySharedResourcesDir(projectBase: File,
+                                             platforms: Seq[Platform],
+                                             conf: String): Option[File] =
+      if (platforms.isEmpty) {
+        None
+      } else {
+        val dir = platforms.map(_.identifier).mkString("-")
+        Some(projectBase.getParentFile / dir / "src" / conf / "resources")
+      }
   }
 
   /**