scalastyle-config.xml

<!--
 To disable scalastyle check for a block of code,

 // scalastyle:off
 ... // some block of code
 // scalastyle:on

 To disable for a single rule,

 // scalastyle:off method.name
 def ::[B >: A](x: B) = ...
 // scalastyle:on method.name

-->
<scalastyle>
  <name>Exasol Scala Scalastyle Configurations (adapted from Spark Scala Style Guide)</name>

  <!-- Check there are no tabs in a file -->
  <check level="error"
    class="org.scalastyle.file.FileTabChecker"
    enabled="true">
  </check>

  <!-- Check that the plus sign is followed by a space -->
  <check level="error"
    class="org.scalastyle.scalariform.SpacesAfterPlusChecker"
    enabled="true">
  </check>

  <!-- Check that the plus sign is preceded by a space -->
  <check level="error"
    class="org.scalastyle.scalariform.SpacesBeforePlusChecker"
    enabled="true">
  </check>

  <!-- Check that there is no trailing whitespace at the end of lines -->
  <check level="error"
    class="org.scalastyle.file.WhitespaceEndOfLineChecker"
    enabled="true">
  </check>

  <!-- Check the number of characters in a line -->
  <check level="error" class="org.scalastyle.file.FileLineLengthChecker" enabled="true">
    <parameters>
      <parameter name="maxLineLength"><![CDATA[120]]></parameter>
      <parameter name="tabSize"><![CDATA[2]]></parameter>
      <parameter name="ignoreImports">true</parameter>
    </parameters>
  </check>

  <!-- Check that class names match a regular expression -->
  <check level="error" class="org.scalastyle.scalariform.ClassNamesChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[[A-Z][A-Za-z]*]]></parameter>
    </parameters>
  </check>

  <!-- Check that object names match a regular expression -->
  <check level="error" class="org.scalastyle.scalariform.ObjectNamesChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[[A-Z][A-Za-z]*]]></parameter>
    </parameters>
  </check>

  <!-- Check that package object names match a regular expression -->
  <check level="error"
    class="org.scalastyle.scalariform.PackageObjectNamesChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[^[a-z][A-Za-z]*$]]></parameter>
    </parameters>
  </check>

  <!-- Maximum number of parameters for a method, after a certain number
       can be hard to understand and keep track
  -->
  <check level="error" class="org.scalastyle.scalariform.ParameterNumberChecker" enabled="true">
    <parameters>
      <parameter name="maxParameters"><![CDATA[8]]></parameter>
    </parameters>
  </check>

  <!-- Check that classes and objects do not define the finalize() method -->
  <check level="error"
    class="org.scalastyle.scalariform.NoFinalizeChecker"
    enabled="true">
  </check>

  <!-- Check that classes and objects do not define equals without overriding
       equals(java.lang.Object)
  -->
  <check level="error"
    class="org.scalastyle.scalariform.CovariantEqualsChecker"
    enabled="true">
  </check>

  <!-- Structural types in Scala can use reflection - this can have unexpected
       performance consequences
  -->
  <check level="error"
    class="org.scalastyle.scalariform.StructuralTypeChecker"
    enabled="true">
  </check>

  <!-- Checks that if a long literal is used, then an uppercase L is used -->
  <check level="error"
    class="org.scalastyle.scalariform.UppercaseLChecker"
    enabled="true">
  </check>

  <!-- Checks that if statements have braces -->
  <check level="error" class="org.scalastyle.scalariform.IfBraceChecker" enabled="true">
    <parameters>
      <parameter name="singleLineAllowed"><![CDATA[true]]></parameter>
      <parameter name="doubleLineAllowed"><![CDATA[false]]></parameter>
    </parameters>
  </check>

  <!-- Check that a method has an explicit return type, it is not inferred -->
  <check level="error"
    class="org.scalastyle.scalariform.PublicMethodsHaveTypeChecker" enabled="true">
    <parameters>
      <parameter name="ignoreOverride">false</parameter>
    </parameters>
  </check>

  <!-- Checks that a file ends with a newline character -->
  <check level="error"
    class="org.scalastyle.file.NewLineAtEofChecker"
    enabled="true">
  </check>

  <!-- Checks that non-ascii characters are not used. Some editors are unfriendly
       to non ascii characters.
  -->
  <check customId="nonascii"
    level="error"
    class="org.scalastyle.scalariform.NonASCIICharacterChecker"
    enabled="true">
  </check>

  <!-- Checks a space after the start of the comment -->
  <check level="error"
    class="org.scalastyle.scalariform.SpaceAfterCommentStartChecker"
    enabled="true">
  </check>

  <!-- Ensure single space before certain token(s) -->
  <check level="error"
    class="org.scalastyle.scalariform.EnsureSingleSpaceBeforeTokenChecker"
    enabled="true">
    <parameters>
      <parameter name="tokens">EQUALS, ELSE, TRY, CATCH, FINALLY, LARROW, RARROW</parameter>
    </parameters>
  </check>

  <!-- Ensure single space after certain token(s) -->
  <check level="error"
    class="org.scalastyle.scalariform.EnsureSingleSpaceAfterTokenChecker"
    enabled="true">
    <parameters>
      <parameter name="tokens">ARROW, EQUALS, COMMA, COLON, IF, ELSE, DO, WHILE, FOR, MATCH, TRY, CATCH, FINALLY, LARROW, RARROW</parameter>
    </parameters>
  </check>

  <!-- Checks '???' are not checked into the code base -->
  <check level="error"
    class="org.scalastyle.scalariform.NotImplementedErrorUsage"
    enabled="true">
  </check>

  <!-- Custom Check: 'println' should not be used -->
  <check customId="println"
    level="error" class="org.scalastyle.scalariform.TokenChecker" enabled="true">
    <parameters>
      <parameter name="regex">^println$</parameter>
    </parameters>
    <customMessage><![CDATA[
      Are you sure you want to println? If yes, wrap the code block with
      // scalastyle:off println
      println(...)
      // scalastyle:on println]]>
    </customMessage>
  </check>

  <!-- Custom Check: 'mutable.SynchronizedBuffer' should not be used -->
  <check customId="mutableSynchronizedbuffer"
    level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">mutable\.SynchronizedBuffer</parameter>
    </parameters>
    <customMessage><![CDATA[
      Are you sure that you want to use mutable.SynchronizedBuffer?
      In most cases, you should use java.util.concurrent.ConcurrentLinkedQueue instead.

      If you must use mutable.SynchronizedBuffer, wrap the code block with
      // scalastyle:off mutablesynchronizedbuffer
      mutable.SynchronizedBuffer[...]
      // scalastyle:on mutablesynchronizedbuffer]]>
    </customMessage>
  </check>

  <!-- Custom Check: 'Class.forName' should not be used -->
  <check customId="classForName"
    level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">Class\.forName</parameter>
    </parameters>
    <customMessage><![CDATA[
      Are you sure that you want to use Class.forName?
      In most cases, you should use Utils.classForName instead.

      If you must use Class.forName, wrap the code block with
      // scalastyle:off classForName
      Class.forName(...)
      // scalastyle:on classForName]]>
    </customMessage>
  </check>

  <!-- Custom Check: 'Await.result' should not be used -->
  <check customId="awaitResult"
    level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">Await\.result</parameter>
    </parameters>
    <customMessage><![CDATA[
      Are you sure that you want to use Await.result?
      In most cases, you should use ThreadUtils.awaitResult instead.

      If you must use Await.result, wrap the code block with
      // scalastyle:off awaitresult
      Await.result(...)
      // scalastyle:on awaitresult]]>
    </customMessage>
  </check>

  <!-- Custom Check: 'Await.ready' should not be used -->
  <check customId="awaitReady"
    level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">Await\.ready</parameter>
    </parameters>
    <customMessage><![CDATA[
      Are you sure that you want to use Await.ready?
      In most cases, you should use ThreadUtils.awaitReady instead.

      If you must use Await.ready, wrap the code block with
      // scalastyle:off awaitready
      Await.ready(...)
      // scalastyle:on awaitready]]>
    </customMessage>
  </check>

  <!-- Custom Check: 'JavaConverters' should be used instead of 'JavaConversions' -->
  <check customId="javaConversions"
    level="error" class="org.scalastyle.scalariform.TokenChecker" enabled="true">
    <parameters>
      <parameter name="regex">JavaConversions</parameter>
    </parameters>
    <customMessage><![CDATA[
      Instead of importing implicits in scala.collection.JavaConversions._
      use instead import scala.collection.JavaConverters._
      and use .asScala / .asJava methods]]>
    </customMessage>
  </check>

  <!-- Custom Check: 'apache.commons.lang3' should be used instead of 'apache.commons.lang' -->
  <check customId="commonsLang2"
    level="error" class="org.scalastyle.scalariform.TokenChecker" enabled="true">
    <parameters>
      <parameter name="regex">org\.apache\.commons\.lang\.</parameter>
    </parameters>
    <customMessage><![CDATA[
      Use Commons Lang 3 classes (package org.apache.commons.lang3.*)
      instead of Commons Lang 2 (package org.apache.commons.lang.*)]]>
    </customMessage>
  </check>

  <!-- Custom Check: 'jsonOption(x).map(.extract[T])' should be used
       instead of '.extractOpt[T]'
  -->
  <check customId="extractOpt"
    level="error" class="org.scalastyle.scalariform.TokenChecker" enabled="true">
    <parameters>
      <parameter name="regex">extractOpt</parameter>
    </parameters>
    <customMessage><![CDATA[
      Use jsonOption(x).map(.extract[T]) instead of .extractOpt[T],
      as the latter is slower.]]>
    </customMessage>
  </check>

  <!-- Custom Check: There should be space between ')' and '{' -->
  <check customId="singleSpaceBetweenRParenAndLCurlyBrace"
    level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">\)\{</parameter>
    </parameters>
    <customMessage><![CDATA[
      There should be a single space character between ')' and `{`]]>
    </customMessage>
  </check>

  <!-- Custom Check: JavaDoc style should be used -->
  <check customId="noScalaDoc"
    level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">(?m)^(\s*)/[*][*].*$(\r|)\n^\1  [*]</parameter>
    </parameters>
    <customMessage><![CDATA[
      Use Javadoc style indentation for multiline comments]]>
    </customMessage>
  </check>

  <!-- Custom Check: Braces should be omitted in case clauses -->
  <check customId="omitBracesInCase"
    level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">case[^\n>]*=>\s*\{</parameter>
    </parameters>
    <customMessage><![CDATA[
      Braces in case clauses should be omitted]]>
    </customMessage>
  </check>

  <!-- Custom Check: Ensure exactly one space between 'if' and '(' -->
  <check  customId="if.paren.spacing"
    level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[if\(|if\s\s+\(]]></parameter>
    </parameters>
    <customMessage><![CDATA[
      Put exactly a single space between 'if' and the following parenthesis]]>
    </customMessage>
  </check>

  <!-- Checks that imports are grouped and ordered according to the style configuration -->
  <!-- Disabled since imports are organized by Scalafix linting. -->
  <check level="error" class="org.scalastyle.scalariform.ImportOrderChecker" enabled="false">
    <parameters>
      <parameter name="groups">java,scala,exasol,others</parameter>
      <parameter name="group.java">javax?\..*</parameter>
      <parameter name="group.scala">scala\..*</parameter>
      <parameter name="group.exasol">com\.exasol\..*</parameter>
      <parameter name="group.others">.*</parameter>
    </parameters>
  </check>

  <!-- Disallow space before certain token(s) -->
  <check level="error"
    class="org.scalastyle.scalariform.DisallowSpaceBeforeTokenChecker"
    enabled="true">
    <parameters>
      <parameter name="tokens">COMMA</parameter>
    </parameters>
  </check>

  <!-- Checks that Java @Override is not used, Scala override keyword should be used instead -->
  <check level="error"
    class="org.scalastyle.scalariform.OverrideJavaChecker"
    enabled="true">
  </check>

  <!-- Checks that Java @Deprecated is not used, Scala @deprecated should be used instead -->
  <check level="error"
    class="org.scalastyle.scalariform.DeprecatedJavaChecker"
    enabled="true">
  </check>

  <!-- No whitespace before left bracket '[', this can be confusing to the reader -->
  <check level="error"
    class="org.scalastyle.scalariform.NoWhitespaceBeforeLeftBracketChecker"
    enabled="true">
  </check>

  <!-- No whitespace after left bracket '[', this can be confusing to the reader -->
  <check level="error"
    class="org.scalastyle.scalariform.NoWhitespaceAfterLeftBracketChecker"
    enabled="true">
  </check>

  <!-- Check that method names match a regular expression -->
  <check level="error" class="org.scalastyle.scalariform.MethodNamesChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[^[a-z][A-Za-z0-9]*$]]></parameter>
    </parameters>
  </check>

  <!-- Checks that methods do not exceed a maximum length -->
  <check level="warn" class="org.scalastyle.scalariform.MethodLengthChecker" enabled="true">
    <parameters>
      <parameter name="maxLength"><![CDATA[120]]></parameter>
    </parameters>
  </check>

  <!-- Check that a class / trait / object does not have too many methods -->
  <check level="error"
    class="org.scalastyle.scalariform.NumberOfMethodsInTypeChecker" enabled="true">
    <parameters>
      <parameter name="maxMethods"><![CDATA[30]]></parameter>
    </parameters>
  </check>

  <!-- Checks that the cyclomatic complexity of a method does exceed a value
       If the code is too complex, then this can make code hard to read.
  -->
  <check level="warn"
    class="org.scalastyle.scalariform.CyclomaticComplexityChecker" enabled="true">
    <parameters>
      <parameter name="maximum"><![CDATA[100]]></parameter>
    </parameters>
  </check>

  <!-- Check that if a class implements either equals or hashCode,
       it should implement the other
  -->
  <check level="error"
    class="org.scalastyle.scalariform.EqualsHashCodeChecker"
    enabled="true">
  </check>

  <!-- Checks for use of magic numbers, avoids assignments like: var baz = 4 -->
  <check level="warn" class="org.scalastyle.scalariform.MagicNumberChecker" enabled="false">
    <parameters>
      <parameter name="ignore"><![CDATA[-1,0,1,2,3,4,5,6,7]]></parameter>
    </parameters>
  </check>

  <!-- Check that return is not used -->
  <check level="error" class="org.scalastyle.scalariform.ReturnChecker" enabled="true"></check>

  <!-- Check that null is not used, prefer Option if possible -->
  <check level="error" class="org.scalastyle.scalariform.NullChecker" enabled="false"></check>

  <!-- Check that classes and objects do not define the clone() method -->
  <check level="error" class="org.scalastyle.scalariform.NoCloneChecker" enabled="true"></check>

  <!-- A boolean expression which can be simplified can make code easier to read -->
  <check level="error"
    class="org.scalastyle.scalariform.SimplifyBooleanExpressionChecker"
    enabled="true">
  </check>

  <!-- Checks that braces are used in for comprehensions -->
  <check level="error" class="org.scalastyle.scalariform.ForBraceChecker" enabled="true"/>

  <!-- Checks that if expressions are not redundant, i.e. easily replaced
       by a variant of the condition
  -->
  <check level="error" class="org.scalastyle.scalariform.RedundantIfChecker" enabled="true"/>

  <!-- Use a : Unit = for procedure declarations -->
  <check level="error"
    class="org.scalastyle.scalariform.ProcedureDeclarationChecker"
    enabled="true"/>

  <!-- Checks that there are not too many types declared in a file -->
  <check level="error" class="org.scalastyle.scalariform.NumberOfTypesChecker" enabled="true">
    <parameters>
      <parameter name="maxTypes"><![CDATA[30]]></parameter>
    </parameters>
  </check>

  <!-- Check a file lines does not exceed threshold (800 default) -->
  <check level="error" class="org.scalastyle.file.FileLengthChecker" enabled="true">
    <parameters>
      <parameter name="maxFileLength"><![CDATA[800]]></parameter>
    </parameters>
  </check>

  <!-- Check that certain classes are not imported -->
  <check level="error" class="org.scalastyle.scalariform.IllegalImportsChecker" enabled="true">
    <parameters>
      <parameter name="illegalImports"><![CDATA[sun._,java.awt._]]></parameter>
    </parameters>
  </check>

  <!-- We want the opposite of this: NewLineAtEofChecker -->
  <check level="error" class="org.scalastyle.file.NoNewLineAtEofChecker" enabled="false"></check>

</scalastyle>