Add LoggerFactory typeclass

build.sbt

@@ -1,3 +1,5 @@
+import com.typesafe.tools.mima.core._
+
 val Scala213 = "2.13.8"
 val Scala212 = "2.12.15"
 val Scala3 = "3.0.2"
@@ -45,7 +47,11 @@ lazy val core = crossProject(JSPlatform, JVMPlatform)
     name := "log4cats-core",
     libraryDependencies ++= Seq(
       "org.typelevel" %%% "cats-core" % catsV
-    )
+    ),
+    libraryDependencies ++= {
+      if (tlIsScala3.value) Seq.empty
+      else Seq("org.scala-lang" % "scala-reflect" % scalaVersion.value % Provided)
+    }
   )
 
 lazy val testing = crossProject(JSPlatform, JVMPlatform)

core/shared/src/main/scala-2/org/typelevel/log4cats/LoggerNameCompat.scala

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2018 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.log4cats
+
+import org.typelevel.log4cats.internal.LoggerNameMacro
+
+trait LoggerNameCompat {
+  implicit def name: LoggerName = macro LoggerNameMacro.getLoggerName
+}

core/shared/src/main/scala-2/org/typelevel/log4cats/internal/LoggerNameMacro.scala

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2018 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.log4cats.internal
+
+import scala.annotation.tailrec
+import scala.reflect.macros.blackbox
+
+private[log4cats] class LoggerNameMacro(val c: blackbox.Context) {
+  final def getLoggerName = SharedLoggerNameMacro.getLoggerNameImpl(c)
+}
+
+private[log4cats] object SharedLoggerNameMacro {
+
+  /** Get a logger by reflecting the enclosing class name. */
+  private[log4cats] def getLoggerNameImpl(c: blackbox.Context) = {
+    import c.universe._
+
+    @tailrec def findEnclosingClass(sym: c.universe.Symbol): c.universe.Symbol = {
+      sym match {
+        case NoSymbol =>
+          c.abort(c.enclosingPosition, s"Couldn't find an enclosing class or module for the logger")
+        case s if s.isModule || s.isClass =>
+          s
+        case other =>
+          /* We're not in a module or a class, so we're probably inside a member definition. Recurse upward. */
+          findEnclosingClass(other.owner)
+      }
+    }
+
+    val cls = findEnclosingClass(c.internal.enclosingOwner)
+
+    assert(cls.isModule || cls.isClass, "Enclosing class is always either a module or a class")
+
+    def nameBySymbol(s: Symbol) = {
+      def fullName(s: Symbol): String = {
+        @inline def isPackageObject = (
+          (s.isModule || s.isModuleClass)
+            && s.owner.isPackage
+            && s.name.decodedName.toString == termNames.PACKAGE.decodedName.toString
+        )
+
+        if (s.isModule || s.isClass) {
+          if (isPackageObject) {
+            s.owner.fullName
+          } else if (s.owner.isStatic) {
+            s.fullName
+          } else {
+            fullName(s.owner) + "." + s.name.encodedName.toString
+          }
+        } else {
+          fullName(s.owner)
+        }
+      }
+
+      q"new _root_.org.typelevel.log4cats.LoggerName(${fullName(s)})"
+    }
+
+    def nameByType(s: Symbol) = {
+      val typeSymbol: ClassSymbol = (if (s.isModule) s.asModule.moduleClass else s).asClass
+      val typeParams = typeSymbol.typeParams
+
+      if (typeParams.isEmpty) {
+        q"new _root_.org.typelevel.log4cats.LoggerName(_root_.scala.Predef.classOf[$typeSymbol].getName)"
+      } else {
+        if (typeParams.exists(_.asType.typeParams.nonEmpty)) {
+          /* We have at least one higher-kinded type: fall back to by-name logger construction, as
+           * there's no simple way to declare a higher-kinded type with an "any" parameter. */
+          nameBySymbol(s)
+        } else {
+          val typeArgs = List.fill(typeParams.length)(WildcardType)
+          val typeConstructor = tq"$typeSymbol[..${typeArgs}]"
+          q"new _root_.org.typelevel.log4cats.LoggerName(_root_.scala.Predef.classOf[$typeConstructor].getName)"
+        }
+      }
+    }
+
+    @inline def isInnerClass(s: Symbol) =
+      s.isClass && !(s.owner.isPackage)
+
+    val instanceByName =
+      (true && cls.isModule || cls.isModuleClass) || (cls.isClass && isInnerClass(
+        cls
+      ))
+
+    if (instanceByName) {
+      nameBySymbol(cls)
+    } else {
+      nameByType(cls)
+    }
+  }
+}

core/shared/src/main/scala-3/org/typelevel/log4cats/LoggerNameCompat.scala

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2018 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.log4cats
+
+import org.typelevel.log4cats.internal.LoggerNameMacro
+
+import scala.quoted.*
+
+trait LoggerNameCompat {
+  implicit inline def name: LoggerName =
+    ${ LoggerNameMacro.getLoggerName }
+}

core/shared/src/main/scala-3/org/typelevel/log4cats/internal/LoggerNameMacro.scala

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2018 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.log4cats
+package internal
+
+import scala.annotation.tailrec
+import scala.quoted.*
+
+private[log4cats] object LoggerNameMacro {
+  def getLoggerName(using qctx: Quotes): Expr[LoggerName] = {
+    val name = getLoggerNameImpl
+    '{ new LoggerName($name) }
+  }
+
+  def getLoggerNameImpl(using qctx: Quotes): Expr[String] = {
+    import qctx.reflect._
+
+    @tailrec def findEnclosingClass(sym: Symbol): Symbol = {
+      sym match {
+        case s if s.isNoSymbol =>
+          report.throwError("Couldn't find an enclosing class or module for the logger")
+        case s if s.isClassDef =>
+          s
+        case other =>
+          /* We're not in a module or a class, so we're probably inside a member definition. Recurse upward. */
+          findEnclosingClass(other.owner)
+      }
+    }
+
+    def symbolName(s: Symbol): Expr[String] = {
+      def fullName(s: Symbol): String = {
+        val flags = s.flags
+        if (flags.is(Flags.Package)) {
+          s.fullName
+        } else if (s.isClassDef) {
+          if (flags.is(Flags.Module)) {
+            if (s.name == "package$") {
+              fullName(s.owner)
+            } else {
+              val chomped = s.name.stripSuffix("$")
+              fullName(s.owner) + "." + chomped
+            }
+          } else {
+            fullName(s.owner) + "." + s.name
+          }
+        } else {
+          fullName(s.owner)
+        }
+      }
+
+      Expr(fullName(s).stripSuffix("$"))
+    }
+
+    val cls = findEnclosingClass(Symbol.spliceOwner)
+    symbolName(cls)
+  }
+}

core/shared/src/main/scala/org/typelevel/log4cats/LoggerFactory.scala

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2018 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.log4cats
+
+import scala.annotation.implicitNotFound
+
+@implicitNotFound("""
+Implicit not found for LoggerFactory[${F}].
+Information can be found here: https://log4cats.github.io/logging-capability.html
+""")
+trait LoggerFactory[F[_]] extends LoggerFactoryGen[F] {
+  type LoggerType = SelfAwareStructuredLogger[F]
+}
+
+object LoggerFactory extends LoggerFactoryGenCompanion {
+  def apply[F[_]: LoggerFactory]: LoggerFactory[F] = implicitly
+}

core/shared/src/main/scala/org/typelevel/log4cats/LoggerFactoryGen.scala

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2018 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.log4cats
+
+trait LoggerFactoryGen[F[_]] {
+  type LoggerType <: Logger[F]
+  def getLogger(implicit name: LoggerName): LoggerType = getLoggerFromName(name.value)
+  def getLoggerFromClass(clazz: Class[_]): LoggerType = getLoggerFromName(clazz.getName)
+  def create(implicit name: LoggerName): F[LoggerType] = fromName(name.value)
+  def fromClass(clazz: Class[_]): F[LoggerType] = fromName(clazz.getName)
+  def getLoggerFromName(name: String): LoggerType
+  def fromName(name: String): F[LoggerType]
+}
+
+private[log4cats] trait LoggerFactoryGenCompanion {
+  def getLogger[F[_]](implicit lf: LoggerFactoryGen[F], name: LoggerName): lf.LoggerType =
+    lf.getLogger
+  def getLoggerFromName[F[_]](name: String)(implicit lf: LoggerFactoryGen[F]): lf.LoggerType =
+    lf.getLoggerFromName(name)
+  def getLoggerFromClass[F[_]](clazz: Class[_])(implicit lf: LoggerFactoryGen[F]): lf.LoggerType =
+    lf.getLoggerFromClass(clazz)
+  def create[F[_]](implicit lf: LoggerFactoryGen[F], name: LoggerName): F[lf.LoggerType] =
+    lf.create
+  def fromName[F[_]](name: String)(implicit lf: LoggerFactoryGen[F]): F[lf.LoggerType] =
+    lf.fromName(name)
+  def fromClass[F[_]](clazz: Class[_])(implicit lf: LoggerFactoryGen[F]): F[lf.LoggerType] =
+    lf.fromClass(clazz)
+}

core/shared/src/main/scala/org/typelevel/log4cats/LoggerName.scala

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2018 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.log4cats
+
+object LoggerName extends LoggerNameCompat
+
+final case class LoggerName(value: String) extends AnyVal

core/shared/src/test/scala/org/typelevel/log4cats/LoggerNameTest.scala

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2018 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.log4cats
+
+import munit.FunSuite
+
+class LoggerNameTest extends FunSuite {
+  class FooA {
+    val name = LoggerName.name
+  }
+
+  object FooB {
+    val name = LoggerName.name
+  }
+
+  test("names") {
+    val name1 = new FooA().name
+    val name2 = FooB.name
+
+    assertEquals(name1.value, "org.typelevel.log4cats.LoggerNameTest.FooA")
+    assertEquals(name2.value, "org.typelevel.log4cats.LoggerNameTest.FooB")
+  }
+}