HeadLastTailInit

rules/src/main/scala/fix/HeadLastTailInit.scala

@@ -0,0 +1,57 @@
+package fix
+
+import scala.meta.Term
+import scalafix.Patch
+import scalafix.lint.Diagnostic
+import scalafix.lint.LintSeverity
+import scalafix.v1.ByNameType
+import scalafix.v1.MethodSignature
+import scalafix.v1.SemanticDocument
+import scalafix.v1.SemanticRule
+import scalafix.v1.TypeRef
+import scalafix.v1.ValueSignature
+import scalafix.v1.XtensionTreeScalafix
+
+class HeadLastTailInit extends SemanticRule("HeadLastTailInit") {
+  private val collectionTypePrefixs: Seq[String] = Seq(
+    "scala.package.",
+    "scala.Predef.",
+    "scala.collection."
+  )
+  private val types: Set[String] = Set(
+    "scala.Array.",
+    "scala.util.Random.shuffle.C."
+  )
+  private def maybeScalaCollection(x: String): Boolean = {
+    types(x) || collectionTypePrefixs.exists(prefix => x.startsWith(prefix))
+  }
+
+  override def fix(implicit doc: SemanticDocument): Patch = {
+    doc.tree.collect {
+      case Term.Select(
+            obj,
+            t @ Term.Name(
+              "head" | "last" | "tail" | "init" | "min" | "max" | "maxBy" | "minBy" | "reduce" | "reduceLeft"
+            )
+          ) =>
+        def p(tpe: String) = Patch.lint(
+          Diagnostic(
+            id = "",
+            message = tpe,
+            position = t.pos,
+            severity = LintSeverity.Warning
+          )
+        )
+        obj.symbol.info.flatMap { i =>
+          PartialFunction.condOpt(i.signature) {
+            case ValueSignature(t: TypeRef) if maybeScalaCollection(t.symbol.normalized.value) =>
+              p(t.symbol.normalized.value)
+            case MethodSignature(_, _, t: TypeRef) if maybeScalaCollection(t.symbol.normalized.value) =>
+              p(t.symbol.normalized.value)
+            case ValueSignature(ByNameType(t: TypeRef)) if maybeScalaCollection(t.symbol.normalized.value) =>
+              p(t.symbol.normalized.value)
+          }
+        }.asPatch
+    }.asPatch
+  }
+}