[WIP] simple di

src/main/scala/io/github/dreamylost/di/DiMacro.scala

+/*
+ * Copyright (c) 2021 jxnu-liguobin && contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package io.github.dreamylost.di
+
+import scala.reflect.macros.whitebox
+import annotation.tailrec
+
+/**
+ * DI Macro
+ *
+ * @author 梦境迷离
+ * @since 2021/7/22
+ * @version 1.0
+ */
+object DiMacro {
+
+  def AutoWire[T]: T = macro AutoWireMacro[T]
+
+  def AutoWireMacro[T: c.WeakTypeTag](c: whitebox.Context): c.Expr[T] = {
+    import c.universe._
+
+    // TODO: this should check if the found value uses AutoWire[]; now any value of the desired type will be returned
+    def findWiredOfType(t: Type): Option[Name] = {
+      @tailrec
+      def doFind(trees: List[Tree]): Option[Name] = trees match {
+        case Nil =>
+          c.error(c.enclosingPosition, s"Cannot find a wired value of type $t")
+          None
+        case tree :: tail => tree match {
+          // TODO: subtyping
+          case ValDef(_, name, tpt, _) if (tpt.tpe weak_<:< t) || (tpt.tpe <:< t) => Some(name.encodedName)
+          case DefDef(defDef) if (defDef._5.tpe weak_<:< t) || (defDef._5.tpe <:< t) => Some(defDef._2.decodedName)
+          case _ => doFind(tail)
+        }
+      }
+
+      val ClassDef(_, _, _, Template(_, _, body)) = c.enclosingClass
+      doFind(body)
+    }
+
+    val tType = implicitly[c.WeakTypeTag[T]]
+    val tConstructorOpt = tType.tpe.members.find(_.name.toTermName.toTermName.toString == "<init>")
+    val result = tConstructorOpt match {
+      case None =>
+        c.error(c.enclosingPosition, "Cannot find constructor for " + tType)
+        reify {
+          null.asInstanceOf[T]
+        }
+      case Some(tConstructor) =>
+        val params = tConstructor.asMethod.paramLists.flatten
+
+        val newT = Select(New(Ident(tType.tpe.typeSymbol)), termNames.CONSTRUCTOR)
+
+        val constructorParams = for (param <- params) yield {
+          val wireTo = findWiredOfType(param.typeSignature)
+            // If we cannot find a value of the given type, trying a by-name match, using the same name as the constructor's parameter.
+            .getOrElse(param.name)
+          Ident(wireTo)
+        }
+
+        val newTWithParams = Apply(newT, constructorParams)
+        c.info(c.enclosingPosition, s"Generated code: ${c.universe.show(newTWithParams)}", force = false)
+        c.Expr(newTWithParams)
+    }
+    result
+  }
+}

src/test/scala/io/github/dreamylost/DiMacroTest.scala

+/*
+ * Copyright (c) 2021 jxnu-liguobin && contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package io.github.dreamylost
+
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
+
+/**
+ *
+ * @author li.guobin@immomo.com
+ * @version 1.0,2021/7/22
+ */
+class DiMacroTest extends AnyFlatSpec with Matchers {
+
+  "wire1" should "ok" in {
+    import io.github.dreamylost.di.DiMacro._
+    class A()
+    class B()
+    class C(a: A, b: B) {
+      override def toString = s"${super.toString}($a, $b)"
+    }
+    class D(b: B, c: C) {
+      override def toString = s"${super.toString}($b, $c)"
+    }
+    trait Service {
+
+      val a = AutoWire[A]
+      val bbb = AutoWire[B]
+      val c = AutoWire[C]
+      val d = AutoWire[D]
+
+      println(a)
+      println(bbb)
+      println(c)
+      println(d)
+    }
+  }
+
+  "wire2" should "ok by parameters inherit" in {
+    import io.github.dreamylost.di.DiMacro._
+
+    class A()
+    class B() extends A
+    class B1
+    class C(b1: B1, a: A) {
+      override def toString = s"${super.toString}($b1, $a)"
+    }
+    trait Service {
+
+      //The instance required by the constructor of the class injected by autowire must be visible within the scope of the enclosingClass.
+      val b1 = AutoWire[B1]
+      val b = AutoWire[B]
+      val c = AutoWire[C]
+      println(b1)
+      println(b)
+      println(c)
+
+    }
+  }
+
+  "wire3" should "ok by lazy and def" in {
+    import io.github.dreamylost.di.DiMacro._
+
+    class A()
+    class B() extends A
+    class B1
+    class C(b1: B1, a: A) {
+      override def toString = s"${super.toString}($b1, $a)"
+    }
+    trait Service {
+
+      lazy val b1 = AutoWire[B1]
+
+      def b: B = AutoWire[B]
+
+      val c = AutoWire[C]
+      println(b1)
+      println(b)
+      println(c)
+
+    }
+  }
+
+}