From 3b10725ee3a1f84855a0654c5e386bc7465816d3 Mon Sep 17 00:00:00 2001
From: Li Haoyi <haoyi.sg@gmail.com>
Date: Sat, 4 Nov 2017 09:09:02 -0700
Subject: First experiment using `Cacher interface` combined with `Caller`
 implicits to turn `def foo = T{}` into pseudo-`lazy val`s, that we can
 override in subclasses using stackable traits

---
 core/src/main/scala/forge/Discovered.scala  |  6 +++++-
 core/src/main/scala/forge/Evaluator.scala   |  1 +
 core/src/main/scala/forge/Target.scala      | 15 ++++++++++++++-
 core/src/main/scala/forge/util/Caller.scala | 12 ++++++++++++
 4 files changed, 32 insertions(+), 2 deletions(-)
 create mode 100644 core/src/main/scala/forge/util/Caller.scala

(limited to 'core/src/main')

diff --git a/core/src/main/scala/forge/Discovered.scala b/core/src/main/scala/forge/Discovered.scala
index 03577b1f..e3aa31f9 100644
--- a/core/src/main/scala/forge/Discovered.scala
+++ b/core/src/main/scala/forge/Discovered.scala
@@ -29,7 +29,11 @@ object Discovered {
     val tpe = c.weakTypeTag[T].tpe
     def rec(segments: List[String], t: c.Type): Seq[Seq[String]] = for {
       m <- t.members.toSeq
-      if m.isTerm && (m.asTerm.isGetter || m.asTerm.isLazy) || m.isModule
+      if
+        (m.isTerm && (m.asTerm.isGetter || m.asTerm.isLazy)) ||
+        m.isModule ||
+        (m.isMethod && m.typeSignature.paramLists.isEmpty && m.typeSignature.resultType <:< c.weakTypeOf[Target[_]])
+
       res <- {
         val extendedSegments = m.name.toString :: segments
         val self =
diff --git a/core/src/main/scala/forge/Evaluator.scala b/core/src/main/scala/forge/Evaluator.scala
index 50dc46d4..3ef605b7 100644
--- a/core/src/main/scala/forge/Evaluator.scala
+++ b/core/src/main/scala/forge/Evaluator.scala
@@ -105,6 +105,7 @@ class Evaluator(workspacePath: Path,
       )
 
       val args = new Args(targetInputValues, targetDestPath)
+
       val res = target.evaluate(args)
       for(targetLabel <- labeling.get(target)){
         terminalResults(target) = targetLabel
diff --git a/core/src/main/scala/forge/Target.scala b/core/src/main/scala/forge/Target.scala
index c1790960..df9d9cc3 100644
--- a/core/src/main/scala/forge/Target.scala
+++ b/core/src/main/scala/forge/Target.scala
@@ -32,6 +32,14 @@ abstract class Target[T] extends Target.Ops[T]{
 }
 
 object Target{
+  trait Cacher{
+    val cacherLazyMap = mutable.Map.empty[(Any, sourcecode.Line, sourcecode.Enclosing), Target[_]]
+    def T[T](t: T): Target[T] = macro impl[T]
+    def T[T](t: => Target[T])
+            (implicit c: forge.util.Caller, l: sourcecode.Line, e: sourcecode.Enclosing): Target[T] = {
+      cacherLazyMap.getOrElseUpdate((c, l, e), t).asInstanceOf[Target[T]]
+    }
+  }
   class Target0[T](t: T) extends Target[T]{
     lazy val t0 = t
     val inputs = Nil
@@ -68,7 +76,12 @@ object Target{
 
     val bindings = symbols.map(c.internal.valDef(_))
 
-    val embedded = q"new forge.Target.Target1(forge.zipMap(..$exprs){ (..$bindings) => $transformed })"
+    val newTargetTree = q"new forge.Target.Target1(forge.zipMap(..$exprs){ (..$bindings) => $transformed })"
+
+    val embedded =
+      if (!(c.prefix.tree.tpe <:< typeOf[Cacher])) newTargetTree
+      else q"${c.prefix}.T($newTargetTree)"
+
 
     c.Expr[Target[T]](embedded)
   }
diff --git a/core/src/main/scala/forge/util/Caller.scala b/core/src/main/scala/forge/util/Caller.scala
new file mode 100644
index 00000000..30dcb22a
--- /dev/null
+++ b/core/src/main/scala/forge/util/Caller.scala
@@ -0,0 +1,12 @@
+package forge.util
+
+import scala.reflect.macros.blackbox
+import language.experimental.macros
+case class Caller(value: Any)
+object Caller {
+  implicit def generate: Caller = macro impl
+  def impl(c: blackbox.Context): c.Tree = {
+    import c.universe._
+    q"new _root_.forge.util.Caller(this)"
+  }
+}
-- 
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