scalastyle-config.xml

<!--
  Copyright 2016 LinkedIn Corp.

  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.
-->
<!--
If you wish to turn off checking for a section of code, you can put a comment in the source
before and after the section, with the following syntax:
  // scalastyle:off
  ...  // code which leads to scalastyle error
  // scalastyle:on

You can also disable only one rule, by specifying its rule id, as specified in:
  http://www.scalastyle.org/rules-1.0.0.html
  // scalastyle:off header.matches
  ...  // file header
  // scalastyle:on header.matches
-->
<scalastyle>
  <name>Scalastyle standard configuration</name>

  <!-- *********************** Issues which will be treated as errors hence enforced *********************** -->
  <!-- File should not contain tabs -->
  <check level="error" class="org.scalastyle.file.FileTabChecker" enabled="true"></check>
  <!-- Scala files should have a header like below -->
  <check level="error" class="org.scalastyle.file.HeaderMatchesChecker" enabled="true">
    <parameters>
      <parameter name="header"><![CDATA[/*
 * Copyright 2016 LinkedIn Corp.
 *
 * 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.
 */]]></parameter>
    </parameters>
  </check>

  <!-- LENGTHS -->
  <!-- Length of the file should be lesser than 2000 lines -->
  <check level="error" class="org.scalastyle.file.FileLengthChecker" enabled="true">
    <parameters>
      <parameter name="maxFileLength"><![CDATA[2000]]></parameter>
    </parameters>
  </check>
  <!-- Length of a line should not exceed 120 characters -->
  <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 level="error" class="org.scalastyle.scalariform.MethodLengthChecker" enabled="true">
    <parameters>
      <parameter name="maxLength"><![CDATA[150]]></parameter>
    </parameters>
  </check>
  <check level="error" class="org.scalastyle.scalariform.ParameterNumberChecker" enabled="true">
    <parameters>
      <parameter name="maxParameters"><![CDATA[7]]></parameter>
    </parameters>
  </check>

  <!-- NAMING CONVENTIONS. Refer to https://docs.scala-lang.org/style/naming-conventions.html -->
  <check level="error" class="org.scalastyle.scalariform.ClassNamesChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[[A-Z][A-Za-z]*]]></parameter>
    </parameters>
  </check>
  <check level="error" class="org.scalastyle.scalariform.ObjectNamesChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[[A-Z][A-Za-z]*]]></parameter>
    </parameters>
  </check>
  <check level="error" class="org.scalastyle.scalariform.MethodNamesChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[^[a-z][A-Za-z0-9]*$]]></parameter>
    </parameters>
  </check>
  <check level="error" class="org.scalastyle.scalariform.PackageObjectNamesChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[^[a-z][A-Za-z]*$]]></parameter>
    </parameters>
  </check>
  <check level="error" class="org.scalastyle.scalariform.ClassTypeParameterChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[^[A-Z_]$]]></parameter>
    </parameters>
  </check>
  <check level="error" class="org.scalastyle.scalariform.FieldNamesChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[^[a-z][A-Za-z0-9]*$]]></parameter>
      <parameter name="objectFieldRegex"><![CDATA[^[A-Z][A-Za-z0-9]*$]]></parameter>
    </parameters>
  </check>
  <check level="error" class="org.scalastyle.scalariform.PackageNamesChecker" enabled="true">
    <parameters>
      <parameter name="regex"><![CDATA[^[a-z][A-Za-z]*$]]></parameter>
    </parameters>
  </check>

  <!-- CODING -->
  <!-- Equals and hash code related rules -->
  <check level="error" class="org.scalastyle.scalariform.EqualsHashCodeChecker" enabled="true"></check>
  <check level="error" class="org.scalastyle.scalariform.CovariantEqualsChecker" enabled="true"></check>

  <check level="error" class="org.scalastyle.scalariform.PublicMethodsHaveTypeChecker" enabled="true">
    <customMessage><![CDATA[Public method declared on a type is like an API. Explicitly declare a return type to ensure
    other code which depends on it won’t break unexpectedly.]]></customMessage>
  </check>
  <check level="error" class="org.scalastyle.scalariform.StructuralTypeChecker" enabled="true">
    <customMessage><![CDATA[Structural types in Scala can use reflection which can have performance
    consequences.]]></customMessage>
  </check>
  <check level="error" class="org.scalastyle.scalariform.NonASCIICharacterChecker" enabled="true"></check>

  <!-- Do not allow a bunch of collections in the package scala.collection.mutable -->
  <check customId="mutablesynchronizedbuffer" level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">mutable\.SynchronizedBuffer</parameter>
    </parameters>
    <customMessage><![CDATA[Synchronization via traits is inherently unreliable. Consider
      java.util.concurrent.ConcurrentLinkedQueue as an alternative. If you must use mutable.SynchronizedBuffer, wrap
      the code block with:
      // scalastyle:off mutablesynchronizedbuffer
      mutable.SynchronizedBuffer[...]
      // scalastyle:on mutablesynchronizedbuffer
    ]]></customMessage>
  </check>
  <check customId="mutablesynchronizedmap" level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">mutable\.SynchronizedMap</parameter>
    </parameters>
    <customMessage><![CDATA[Synchronization via traits is inherently unreliable. Consider
      java.util.concurrent.ConcurrentHashMap as an alternative. If you must use mutable.SynchronizedMap, wrap
      the code block with:
      // scalastyle:off mutablesynchronizedmap
      mutable.SynchronizedMap[...]
      // scalastyle:on mutablesynchronizedmap
    ]]></customMessage>
  </check>
  <check customId="mutablesynchronizedset" level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">mutable\.SynchronizedSet</parameter>
    </parameters>
    <customMessage><![CDATA[Synchronization via traits is inherently unreliable. Consider
      java.util.concurrent.ConcurrentHashMap[A,Unit] as an alternative. If you must use mutable.SynchronizedSet, wrap
      the code block with:
      // scalastyle:off mutablesynchronizedset
      mutable.SynchronizedSet[...]
      // scalastyle:on mutablesynchronizedset
    ]]></customMessage>
  </check>
  <check customId="mutablesynchronizedqueue" level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">mutable\.SynchronizedQueue</parameter>
    </parameters>
    <customMessage><![CDATA[Synchronization via selective overriding of methods is inherently unreliable. Consider
      java.util.concurrent.ConcurrentLinkedQueue as an alternative. If you must use mutable.SynchronizedQueue, wrap
      the code block with:
      // scalastyle:off mutablesynchronizedqueue
      mutable.SynchronizedQueue[...]
      // scalastyle:on mutablesynchronizedqueue
    ]]></customMessage>
  </check>
  <check customId="mutablesynchronizedpriorityqueue" level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">mutable\.SynchronizedPriorityQueue</parameter>
    </parameters>
    <customMessage><![CDATA[Synchronization via selective overriding of methods is inherently unreliable. Consider
      java.util.concurrent.ConcurrentSkipListSet as an alternative. If you must use mutable.SynchronizedPriorityQueue, wrap
      the code block with:
      // scalastyle:off mutablesynchronizedpriorityqueue
      mutable.SynchronizedPriorityQueue[...]
      // scalastyle:on mutablesynchronizedpriorityqueue
    ]]></customMessage>
  </check>
  <check customId="mutablesynchronizedstack" level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">mutable\.SynchronizedStack</parameter>
    </parameters>
    <customMessage><![CDATA[Synchronization via selective overriding of methods is inherently unreliable. Consider
      java.util.concurrent.LinkedBlockingDequeue as an alternative. If you must use mutable.SynchronizedStack, wrap
      the code block with:
      // scalastyle:off mutablesynchronizedstack
      mutable.SynchronizedStack[...]
      // scalastyle:on mutablesynchronizedstack
    ]]></customMessage>
  </check>
  <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>
  <check customId="javaconversions" level="error" class="org.scalastyle.scalariform.TokenChecker" enabled="true">
    <parameters><parameter name="regex">JavaConversions</parameter></parameters>
    <customMessage>Instead of importing implicits in scala.collection.JavaConversions._, import
    scala.collection.JavaConverters._ and use .asScala / .asJava methods</customMessage>
  </check>
  <check customId="throwerror" level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
    <parameters>
      <parameter name="regex">throw new \w+Error\(</parameter>
    </parameters>
    <customMessage><![CDATA[Instead of throwing Error, you should use appropriate Exception instead.
      If you must throw Error, wrap the code block with
      // scalastyle:off throwerror
      throw new XXXError(...)
      // scalastyle:on throwerror
    ]]></customMessage>
  </check>
  <check level="error" class="org.scalastyle.scalariform.NoFinalizeChecker" enabled="true"></check>

  <!-- MISCELLANEOUS -->
  <check level="error" class="org.scalastyle.scalariform.CyclomaticComplexityChecker" enabled="true">
    <parameters>
      <parameter name="maximum"><![CDATA[15]]></parameter>
    </parameters>
  </check>
  <!-- Indentation settings -->
  <check level="error" class="org.scalastyle.file.IndentationChecker" enabled="true">
    <parameters>
      <parameter name="tabSize">2</parameter>
      <parameter name="methodParamIndentSize">2</parameter>
      <parameter name="classParamIndentSize">2</parameter>
    </parameters>
  </check>

  <!-- *********************** Issues which will be treated as warnings *********************** -->
  <!-- WHITESPACE -->
  <check level="warning" class="org.scalastyle.scalariform.SpacesAfterPlusChecker" enabled="true"></check>
  <check level="warning" class="org.scalastyle.file.WhitespaceEndOfLineChecker" enabled="true"></check>
  <check level="warning" class="org.scalastyle.scalariform.SpacesBeforePlusChecker" enabled="true"></check>
  <check level="warning" class="org.scalastyle.scalariform.NoWhitespaceBeforeLeftBracketChecker" enabled="true"></check>
  <check level="warning" class="org.scalastyle.scalariform.NoWhitespaceAfterLeftBracketChecker" enabled="true"></check>
  <check level="warning" class="org.scalastyle.scalariform.EnsureSingleSpaceBeforeTokenChecker" enabled="true">
   <parameters>
     <parameter name="tokens">ARROW, EQUALS, ELSE, TRY, CATCH, FINALLY, LARROW, RARROW</parameter>
   </parameters>
  </check>
  <check level="warning" 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>

  <!-- IMPORTS -->
  <check level="warning" class="org.scalastyle.scalariform.IllegalImportsChecker" enabled="true">
    <parameters>
      <parameter name="illegalImports"><![CDATA[sun._,java.awt._]]></parameter>
    </parameters>
  </check>

  <!-- CODING -->
  <check level="warning" class="org.scalastyle.scalariform.NullChecker" enabled="true">
    <customMessage><![CDATA[Scala discourages use of nulls. Use Option instead]]></customMessage>
  </check>
  <check level="warning" class="org.scalastyle.scalariform.MagicNumberChecker" enabled="true">
    <parameters>
      <parameter name="ignore"><![CDATA[-1,0,1,2,3]]></parameter>
    </parameters>
  </check>
  <check level="warning" class="org.scalastyle.scalariform.ReturnChecker" enabled="true"></check>
  <check level="warning" class="org.scalastyle.scalariform.NumberOfTypesChecker" enabled="true">
    <parameters>
      <parameter name="maxTypes"><![CDATA[30]]></parameter>
    </parameters>
  </check>
  <check level="warning" class="org.scalastyle.scalariform.UppercaseLChecker" enabled="true"></check>
  <check level="warning" class="org.scalastyle.scalariform.SimplifyBooleanExpressionChecker" enabled="false"></check>
  <check level="warning" class="org.scalastyle.scalariform.IfBraceChecker" enabled="true">
    <parameters>
      <parameter name="singleLineAllowed"><![CDATA[true]]></parameter>
      <parameter name="doubleLineAllowed"><![CDATA[true]]></parameter>
    </parameters>
  </check>
  <check level="warning" class="org.scalastyle.scalariform.ForBraceChecker" enabled="true"/>
  <check level="warning" class="org.scalastyle.scalariform.NoCloneChecker" enabled="true"></check>
  <!-- Use Scala @deprecated instead of Java @Deprecated -->
  <check level="warning" class="org.scalastyle.scalariform.DeprecatedJavaChecker" enabled="true"></check>
  <!-- Use Scala override instead of Java Override -->
  <check level="warning" class="org.scalastyle.scalariform.OverrideJavaChecker" enabled="true"></check>
  <check level="warning" class="org.scalastyle.scalariform.LowercasePatternMatchChecker" enabled="true"/>
  <!-- Use constants instead of multiple string literals. As there can be multiple unnecessary issues
       reported, keeping it at warning severity. Committers though should pay attention to this issue
       and ask contributors to fix wherever they deem fit -->
  <check level="warning" class="org.scalastyle.scalariform.MultipleStringLiteralsChecker" enabled="true">
    <parameters>
      <parameter name="allowed">2</parameter>
      <parameter name="ignoreRegex"><![CDATA[^(("")|(")|(", "))$]]></parameter>
    </parameters>
  </check>

  <!-- MISCELLANEOUS -->
  <check level="warning" class="org.scalastyle.scalariform.NumberOfMethodsInTypeChecker" enabled="true">
    <parameters>
      <parameter name="maxMethods"><![CDATA[30]]></parameter>
    </parameters>
  </check>

  <!-- SCALADOC related -->
  <check level="warning" class="org.scalastyle.scalariform.ScalaDocChecker" enabled="true">
    <parameters>
      <parameter name="ignoreRegex"><![CDATA[(.*Spec$)|(.*SpecIT$)]]></parameter>
      <parameter name="ignoreTokenTypes">PatDefOrDcl,TypeDefOrDcl,FunDefOrDcl,TmplDef</parameter>
      <parameter name="ignoreOverride">false</parameter>
      <parameter name="indentStyle">javadoc</parameter>
    </parameters>
  </check>

  <!-- *********************** Issues which are ignored for now *********************** -->
  <check level="warning" class="org.scalastyle.file.NewLineAtEofChecker" enabled="false"></check>
  <check level="warning" class="org.scalastyle.file.NoNewLineAtEofChecker" enabled="false"></check>
  <check level="warning" class="org.scalastyle.scalariform.BlockImportChecker" enabled="false"/>
  <check level="warning" class="org.scalastyle.scalariform.VarFieldChecker" enabled="false"/>
  <check level="warning" class="org.scalastyle.scalariform.VarLocalChecker" enabled="false"/>
  <check level="warning" class="org.scalastyle.scalariform.WhileChecker" enabled="false"/>
  <check level="warning" class="org.scalastyle.scalariform.XmlLiteralChecker" enabled="false"/>
  <check level="warning" class="org.scalastyle.scalariform.UnderscoreImportChecker" enabled="false">
    <parameters>
      <parameter name="ignoreRegex"><![CDATA[collection\.JavaConverters\._|scala\.concurrent\.duration\._]]></parameter>
    </parameters>
  </check>
</scalastyle>