org.gerweck.scala.util.SupportMacros.scala Maven / Gradle / Ivy

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General utilies for Scala applications

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package org.gerweck.scala.util

import scala.reflect.macros.whitebox.Context

import org.log4s._

private[util] object SupportMacros {
  def support_simple(c: Context): c.Expr[Nothing] = {
    import c.universe._

    val callerName = getCallerName(c)

    val message = s"Method `$callerName` not supported"

    c.Expr[Nothing](q"throw new java.lang.UnsupportedOperationException($message)")
  }

  def support_complex(c: Context)(logger: c.Expr[Logger], level: c.Expr[LogLevel]): c.Expr[Nothing] = {
    import c.universe._

    val callerName = getCallerName(c)

    val exceptionMessage = s"Method `$callerName` not supported"
    val logMessage = s"Got unsupported call to `$callerName`"

    c.Expr[Nothing](q"""$logger($level)($logMessage)
                        throw new java.lang.UnsupportedOperationException($exceptionMessage)""")
  }

  // TODO: Reduce code duplication.
  def support_warn(c: Context): c.Expr[Nothing] = {
    import c.universe._

    val callerName = getCallerName(c)
    val logMessage = s"Got unsupported call to `$callerName`"
    val exceptionMessage = s"Method `$callerName` is not supported"

    c.Expr[Nothing](q"""logger.warn($logMessage)
                        throw new java.lang.UnsupportedOperationException($exceptionMessage)""")
  }

  @inline private def getCallerName(c: Context): String = {
    val own = c.internal.enclosingOwner
    own match {
      case s if s.isMethod =>
        s.asMethod.name.decodedName.toString
      case _ =>
        c.abort(c.enclosingPosition, "org.gerweck.scala.util.Support.support may only be used directly inside a named method")
    }
  }
}