fix.ObjectFinal.scala Maven / Gradle / Ivy

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package fix

import scala.meta.Defn
import scala.meta.Mod
import scala.meta.Pat
import scala.meta.Term
import scala.meta.Type
import scala.meta.XtensionClassifiable
import scala.meta.XtensionCollectionLikeUI
import scala.meta.XtensionStructure
import scalafix.Patch
import scalafix.lint.Diagnostic
import scalafix.lint.LintSeverity
import scalafix.v1.SyntacticDocument
import scalafix.v1.SyntacticRule
import scalafix.v1.XtensionSeqPatch

object ObjectFinal {
  private val constantTypes: Seq[Type] = {
    val values = Seq(
      "Boolean",
      "Byte",
      "Short",
      "Char",
      "Int",
      "Long",
      "Float",
      "Double",
    ).map(Type.Name.apply)

    Seq(
      values.flatMap { x =>
        Seq(
          x,
          Type.Select(
            Term.Name("scala"),
            x,
          ),
          Type.Select(
            Term.Select(
              Term.Name("_root_"),
              Term.Name("scala")
            ),
            x
          )
        )
      }, {
        val str = Type.Name("String")

        Seq(
          str,
          Type.Select(
            Term.Name("Predef"),
            str,
          ),
          Type.Select(
            Term.Select(
              Term.Name("scala"),
              Term.Name("Predef")
            ),
            str
          ),
          Type.Select(
            Term.Select(
              Term.Select(
                Term.Name("_root_"),
                Term.Name("scala")
              ),
              Term.Name("Predef")
            ),
            str
          ),
          Type.Select(
            Term.Select(
              Term.Name("java"),
              Term.Name("lang")
            ),
            str
          ),
          Type.Select(
            Term.Select(
              Term.Select(
                Term.Name("_root_"),
                Term.Name("java")
              ),
              Term.Name("lang")
            ),
            str
          ),
        )
      }
    ).flatten
  }

  private object FinalMod {
    def unapply(values: List[Mod]): Option[Mod] = values.find(_.is[Mod.Final])
  }
}

class ObjectFinal extends SyntacticRule("ObjectFinal") {

  override def fix(implicit doc: SyntacticDocument): Patch = {
    doc.tree.collect { case o: Defn.Object =>
      o.templ.body.stats.collect {
        case Defn.Val(
              ObjectFinal.FinalMod(m),
              List(Pat.Var(_: Term.Name)),
              Some(tpe),
              _
            ) if ObjectFinal.constantTypes.forall(_.structure != tpe.structure) =>
          Patch.lint(
            Diagnostic(
              id = "",
              message =
                "redundant `final` for val if not constant https://scala-lang.org/files/archive/spec/2.13/06-expressions.html#constant-expressions",
              position = m.pos,
              severity = LintSeverity.Warning
            )
          )
        case Defn.Def.After_4_7_3(
              ObjectFinal.FinalMod(m),
              _,
              _,
              _,
              _
            ) =>
          Patch.lint(
            Diagnostic(
              id = "",
              message = "redundant final",
              position = m.pos,
              severity = LintSeverity.Warning
            )
          )
      }.asPatch
    }.asPatch
  }
}