From b2574e67305954dae04947448961793fb095e161 Mon Sep 17 00:00:00 2001
From: David Denton <denton.david@gmail.com>
Date: Mon, 11 Sep 2017 08:32:16 +0100
Subject: [PATCH] started introducing lenses

---
 src/test/scala/lens/LensExtractor.scala | 17 ++++++++
 src/test/scala/lens/LensInjector.scala  | 18 ++++++++
 src/test/scala/lens/Lenses.scala        | 55 +++++++++++++++++++++++++
 3 files changed, 90 insertions(+)
 create mode 100644 src/test/scala/lens/LensExtractor.scala
 create mode 100644 src/test/scala/lens/LensInjector.scala
 create mode 100644 src/test/scala/lens/Lenses.scala

diff --git a/src/test/scala/lens/LensExtractor.scala b/src/test/scala/lens/LensExtractor.scala
new file mode 100644
index 00000000..4969e202
--- /dev/null
+++ b/src/test/scala/lens/LensExtractor.scala
@@ -0,0 +1,17 @@
+package lens
+
+trait LensExtractor[IN, OUT] extends Function[IN, OUT] {
+  /**
+    * Lens operation to get the value from the target
+    *
+    * @throws LensFailure if the value could not be retrieved from the target (missing/invalid etc)
+    */
+  override def apply(target: IN): OUT
+
+  /**
+    * Lens operation to get the value from the target. Synonym for invoke(IN)
+    *
+    * @throws LensFailure if the value could not be retrieved from the target (missing/invalid etc)
+    */
+  def extract(target: IN): OUT = apply(target)
+}
diff --git a/src/test/scala/lens/LensInjector.scala b/src/test/scala/lens/LensInjector.scala
new file mode 100644
index 00000000..ebf89293
--- /dev/null
+++ b/src/test/scala/lens/LensInjector.scala
@@ -0,0 +1,18 @@
+package lens
+
+trait LensInjector[IN, OUT] {
+  /**
+    * Lens operation to set the value into the target
+    */
+  def apply[R <: IN](value: OUT, target: R): R
+
+  /**
+    * Lens operation to set the value into the target. Synomym for invoke(OUT, IN)
+    */
+  def inject[R <: IN](value: OUT, target: R): R = apply(value, target)
+
+  /**
+    * Bind this Lens to a value, so we can set it into a target
+    */
+  def of[R <: IN](value: OUT): (R) => R = apply(value, _)
+}
diff --git a/src/test/scala/lens/Lenses.scala b/src/test/scala/lens/Lenses.scala
new file mode 100644
index 00000000..009ca595
--- /dev/null
+++ b/src/test/scala/lens/Lenses.scala
@@ -0,0 +1,55 @@
+package lens
+
+import io.fintrospect.parameters.ParamType
+
+class LensGet[IN, MID, OUT] private(private val rootFn: (String, IN) => List[MID], private val fn: (MID) => OUT) {
+  def map[NEXT](nextFn: (OUT) => NEXT): LensGet[IN, MID, NEXT] = new LensGet[IN, MID, NEXT](rootFn, (i: MID) => nextFn(fn(i)))
+}
+
+object LensGet {
+  def apply[IN, OUT](rootFn: (String, IN) => List[OUT]): LensGet[IN, OUT, OUT] = new LensGet(rootFn, (i: OUT) => i)
+}
+
+class LensSet[IN, MID, OUT] private(private val rootFn: (String, List[MID], IN) => IN, private val fn: (OUT) => MID) {
+  def map[NEXT](nextFn: (NEXT) => OUT): LensSet[IN, MID, NEXT] = new LensSet[IN, MID, NEXT](rootFn, (value: NEXT) => fn(nextFn(value)))
+}
+
+object LensSet {
+  def apply[IN, OUT](rootFn: (String, List[OUT], IN) => IN): LensSet[IN, OUT, OUT] = new LensSet(rootFn, (i: OUT) => i)
+}
+
+///**
+//  * A Lens provides the uni-directional extraction of an entity from a target.
+//  */
+// class Lens[IN, FINAL](val meta: Meta,
+//private val get: (IN) =] FINAL) : LensExtractor[IN, FINAL], Iterable[Meta] {
+//
+//  import shapeless.PolyDefns.=]
+//
+//  override defiterator(): Iterator[Meta] = listOf(meta).iterator()
+//
+//  override deftoString(): String = "${if (meta.required) "Required" else "Optional"} ${meta.location} '${meta.name}'"
+//
+//  override  definvoke(target: IN): FINAL = try {
+//  get(target)
+//} catch (e: LensFailure) {
+//  throw e
+//} catch (e: Exception) {
+//  throw LensFailure(Invalid(meta), cause = e)
+//}
+//}
+//
+//  /**
+//    * A BiDiLens provides the bi-directional extraction of an entity from a target, or the insertion of an entity
+//    * into a target.
+//    */
+//  class BiDiLens[IN, FINAL](meta: Meta,
+//  get: (IN) =] FINAL,
+//  private val set: (FINAL, IN) =] IN) : LensInjector[IN, FINAL], Lens[IN, FINAL](meta, get) {
+//
+//  @Suppress("UNCHECKED_CAST")
+//  override  def[R : IN] invoke(value: FINAL, target: R): R = set(value, target) as R
+//}
+
+
+case class Meta(required: Boolean, location: String, paramMeta: ParamType, name: String, description: Option[String] = null)
\ No newline at end of file