scalastyle-config.xml

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  ~ Copyright (2021) Databricks, Inc.
  ~ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
  ~ INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
  ~ AND NONINFRINGEMENT.
  ~
  ~ IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  ~ LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  ~ TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
  ~ THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  ~
  ~ See the Full License for the specific language governing permissions and
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<!--

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
  ...  // stuff that breaks the styles
  // scalastyle:on

You can also disable only one rule, by specifying its rule id, as specified in:
  http://www.scalastyle.org/rules-0.7.0.html

  // scalastyle:off no.finalize
  override def finalize(): Unit = ...
  // scalastyle:on no.finalize

This file is divided into 3 sections:
 (1) rules that we enforce.
 (2) rules that we would like to enforce, but haven't cleaned up the codebase to turn on yet
     (or we need to make the scalastyle rule more configurable).
 (3) rules that we don't want to enforce.
-->

<scalastyle>
    <name>Scalastyle standard configuration</name>

    <!-- ================================================================================ -->
    <!--                               rules we enforce                                   -->
    <!-- ================================================================================ -->

    <check level="error" class="org.scalastyle.file.FileTabChecker" enabled="true"></check>

    <check level="error" class="org.scalastyle.file.HeaderMatchesChecker" enabled="true">
        <parameters>
            <parameter name="regex">true</parameter>
            <parameter name="header"><![CDATA[(?:\Q/*
 * Copyright (2021) Databricks, Inc.
 *
 * This library (the "Software") may not be used except in connection with the Licensee's use of the Databricks Platform Services pursuant
 * to an Agreement (defined below) between Licensee (defined below) and Databricks, Inc. ("Databricks"). The Object Code version of the
 * Software shall be deemed part of the Downloadable Services under the Agreement, or if the Agreement does not define Downloadable Services,
 * Subscription Services, or if neither are defined then the term in such Agreement that refers to the applicable Databricks Platform
 * Services (as defined below) shall be substituted herein for �Downloadable Services.�  Licensee's use of the Software must comply at
 * all times with any restrictions applicable to the Downlodable Services and Subscription Services, generally, and must be used in
 * accordance with any applicable documentation. For the avoidance of doubt, the Software constitutes Databricks Confidential Information
 * under the Agreement.
 *
 * Additionally, and notwithstanding anything in the Agreement to the contrary:
 * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 *   LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
 *   IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * * you may view, make limited copies of, and may compile the Source Code version of the Software into an Object Code version of the
 *   Software.  For the avoidance of doubt, you may not make derivative works of Software (or make any any changes to the Source Code
 *   version of the unless you have agreed to separate terms with Databricks permitting such modifications (e.g., a contribution license
 *   agreement)).
 *
 * If you have not agreed to an Agreement or otherwise do not agree to these terms, you may not use the Software or view, copy or compile
 * the Source Code of the Software.

 * This license terminates automatically upon the termination of the Agreement or Licensee's breach of these terms.  Additionally,
 * Databricks may terminate this license at any time on notice.  Upon termination, you must permanently delete the Software and all
 * copies thereof (including the Source Code).
 *
 * Agreement: the agreement between Databricks and Licensee governing the use of the Databricks Platform Services, which shall be, with
 * respect to Databricks, the Databricks Terms of Service located at www.databricks.com/termsofservice, and with respect to Databricks
 * Community Edition, the Community Edition Terms of Service located at www.databricks.com/ce-termsofuse, in each case unless Licensee
 * has entered into a separate written agreement with Databricks governing the use of the applicable Databricks Platform Services.
 *
 * Databricks Platform Services: the Databricks services or the Databricks Community Edition services, according to where the Software is used.
 *
 * Licensee: the user of the Software, or, if the Software is being used on behalf of a company, the company.
 *
 * Object Code: is version of the Software produced when an interpreter or a compiler translates the Source Code into recognizable and
 * executable machine code.
 *
 * Source Code: the human readable portion of the Software.
 */
\E)?\Q/*
 * Copyright (2021) Databricks, Inc.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * AND NONINFRINGEMENT.
 *
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
 * THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * See the Full License for the specific language governing permissions and
 * limitations under the License.
 */\E]]></parameter>
        </parameters>
    </check>

    <check level="error" class="org.scalastyle.scalariform.SpacesAfterPlusChecker"
           enabled="true"></check>

    <check level="error" class="org.scalastyle.scalariform.SpacesBeforePlusChecker"
           enabled="true"></check>

    <check level="error" class="org.scalastyle.file.WhitespaceEndOfLineChecker"
           enabled="true"></check>

    <check level="error" class="org.scalastyle.file.FileLineLengthChecker" enabled="true">
        <parameters>
            <parameter name="maxLineLength"><![CDATA[100]]></parameter>
            <parameter name="tabSize"><![CDATA[2]]></parameter>
            <parameter name="ignoreImports">true</parameter>
        </parameters>
    </check>

    <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[(config|[A-Z][A-Za-z]*)]]></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 customId="argcount" level="error"
           class="org.scalastyle.scalariform.ParameterNumberChecker" enabled="true">
        <parameters>
            <parameter name="maxParameters"><![CDATA[10]]></parameter>
        </parameters>
    </check>

    <check level="error" class="org.scalastyle.scalariform.NoFinalizeChecker"
           enabled="true"></check>

    <check level="error" class="org.scalastyle.scalariform.CovariantEqualsChecker"
           enabled="true"></check>

    <check level="error" class="org.scalastyle.scalariform.StructuralTypeChecker"
           enabled="true"></check>

    <check level="error" class="org.scalastyle.scalariform.UppercaseLChecker"
           enabled="true"></check>

    <check level="error" class="org.scalastyle.scalariform.IfBraceChecker" enabled="true">
        <parameters>
            <parameter name="singleLineAllowed"><![CDATA[true]]></parameter>
            <parameter name="doubleLineAllowed"><![CDATA[true]]></parameter>
        </parameters>
    </check>

    <check level="error" class="org.scalastyle.scalariform.PublicMethodsHaveTypeChecker"
           enabled="true"></check>

    <check level="error" class="org.scalastyle.file.NewLineAtEofChecker" enabled="true"></check>

    <check customId="nonascii" level="error"
           class="org.scalastyle.scalariform.NonASCIICharacterChecker" enabled="true"></check>

    <check level="error" class="org.scalastyle.scalariform.SpaceAfterCommentStartChecker"
           enabled="true"></check>

    <check level="error" class="org.scalastyle.scalariform.EnsureSingleSpaceBeforeTokenChecker"
           enabled="true">
        <parameters>
            <parameter name="tokens">ARROW, EQUALS, ELSE, TRY, CATCH, FINALLY, LARROW, RARROW
            </parameter>
        </parameters>
    </check>

    <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>

    <!-- ??? usually shouldn't be checked into the code base. -->
    <check level="error" class="org.scalastyle.scalariform.NotImplementedErrorUsage"
           enabled="true"></check>

    <!-- As of SPARK-7558, all tests in Spark should extend o.a.s.SparkFunSuite instead of FunSuite directly -->
    <check customId="funsuite" level="error" class="org.scalastyle.scalariform.TokenChecker"
           enabled="true">
        <parameters>
            <parameter name="regex">^FunSuite[A-Za-z]*$</parameter>
        </parameters>
        <customMessage>Tests must extend org.apache.spark.SparkFunSuite instead.</customMessage>
    </check>

    <!-- As of SPARK-7977 all printlns need to be wrapped in '// scalastyle:off/on println' -->
    <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="hadoopconfiguration" level="error" class="org.scalastyle.file.RegexChecker"
           enabled="true">
        <parameters>
            <parameter name="regex">spark(.sqlContext)?.sparkContext.hadoopConfiguration</parameter>
        </parameters>
        <customMessage><![CDATA[
      Are you sure that you want to use sparkContext.hadoopConfiguration? In most cases, you should use
      spark.sessionState.newHadoopConf() instead, so that the hadoop configurations specified in Spark session
      configuration will come into effect.
      If you must use sparkContext.hadoopConfiguration, wrap the code block with
      // scalastyle:off hadoopconfiguration
      spark.sparkContext.hadoopConfiguration...
      // scalastyle:on hadoopconfiguration
    ]]></customMessage>
    </check>

    <check customId="visiblefortesting" level="error" class="org.scalastyle.file.RegexChecker"
           enabled="true">
        <parameters>
            <parameter name="regex">@VisibleForTesting</parameter>
        </parameters>
        <customMessage><![CDATA[
      @VisibleForTesting causes classpath issues. Please note this in the java doc instead (SPARK-11615).
    ]]></customMessage>
    </check>

    <check customId="runtimeaddshutdownhook" level="error" class="org.scalastyle.file.RegexChecker"
           enabled="true">
        <parameters>
            <parameter name="regex">Runtime\.getRuntime\.addShutdownHook</parameter>
        </parameters>
        <customMessage><![CDATA[
      Are you sure that you want to use Runtime.getRuntime.addShutdownHook? In most cases, you should use
      ShutdownHookManager.addShutdownHook instead.
      If you must use Runtime.getRuntime.addShutdownHook, wrap the code block with
      // scalastyle:off runtimeaddshutdownhook
      Runtime.getRuntime.addShutdownHook(...)
      // scalastyle:on runtimeaddshutdownhook
    ]]></customMessage>
    </check>

    <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>

    <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>

    <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>

    <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>

    <check customId="caselocale" level="error" class="org.scalastyle.file.RegexChecker"
           enabled="true">
        <parameters>
            <parameter name="regex">(\.toUpperCase|\.toLowerCase)(?!(\(|\(Locale.ROOT\)))
            </parameter>
        </parameters>
        <customMessage><![CDATA[
      Are you sure that you want to use toUpperCase or toLowerCase without the root locale? In most cases, you
      should use toUpperCase(Locale.ROOT) or toLowerCase(Locale.ROOT) instead.
      If you must use toUpperCase or toLowerCase without the root locale, wrap the code block with
      // scalastyle:off caselocale
      .toUpperCase
      .toLowerCase
      // scalastyle:on caselocale
    ]]></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[
      Are you sure that you want to throw Error? In most cases, 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>

    <!-- As of SPARK-9613 JavaConversions should be replaced with JavaConverters -->
    <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="commonslang2" level="error" class="org.scalastyle.scalariform.TokenChecker"
           enabled="true">
        <parameters>
            <parameter name="regex">org\.apache\.commons\.lang\.</parameter>
        </parameters>
        <customMessage>Use Commons Lang 3 classes (package org.apache.commons.lang3.*) instead
            of Commons Lang 2 (package org.apache.commons.lang.*)
        </customMessage>
    </check>

    <check customId="extractopt" level="error" class="org.scalastyle.scalariform.TokenChecker"
           enabled="true">
        <parameters>
            <parameter name="regex">extractOpt</parameter>
        </parameters>
        <customMessage>Use jsonOption(x).map(.extract[T]) instead of .extractOpt[T], as the latter
            is slower.
        </customMessage>
    </check>

    <check level="error" class="org.scalastyle.scalariform.DisallowSpaceBeforeTokenChecker"
           enabled="true">
        <parameters>
            <parameter name="tokens">COMMA</parameter>
        </parameters>
    </check>

    <!-- SPARK-3854: Single Space between ')' and '{' -->
    <check customId="SingleSpaceBetweenRParenAndLCurlyBrace" level="error"
           class="org.scalastyle.file.RegexChecker" enabled="true">
        <parameters>
            <parameter name="regex">\)\{</parameter>
        </parameters>
        <customMessage><![CDATA[
      Single Space between ')' and `{`.
    ]]></customMessage>
    </check>

    <check customId="NoScalaDoc" level="error" class="org.scalastyle.file.RegexChecker"
           enabled="true">
        <parameters>
            <parameter name="regex">(?m)^(\s*)/[*][*].*$(\r|)\n^\1 [*]</parameter>
        </parameters>
        <customMessage>Use Javadoc style indentation for multiline comments</customMessage>
    </check>

    <check customId="OmitBracesInCase" level="error" class="org.scalastyle.file.RegexChecker"
           enabled="true">
        <parameters>
            <parameter name="regex">case[^\n>]*=>\s*\{</parameter>
        </parameters>
        <customMessage>Omit braces in case clauses.</customMessage>
    </check>

    <!-- SPARK-16877: Avoid Java annotations -->
    <check level="error" class="org.scalastyle.scalariform.OverrideJavaChecker"
           enabled="true"></check>

    <check level="error" class="org.scalastyle.scalariform.DeprecatedJavaChecker"
           enabled="true"></check>

    <!-- ================================================================================ -->
    <!--       rules we'd like to enforce, but haven't cleaned up the codebase yet        -->
    <!-- ================================================================================ -->

    <!-- We cannot turn the following two on, because it'd fail a lot of string interpolation use cases. -->
    <!-- Ideally the following two rules should be configurable to rule out string interpolation. -->
    <check level="error" class="org.scalastyle.scalariform.NoWhitespaceBeforeLeftBracketChecker"
           enabled="false"></check>
    <check level="error" class="org.scalastyle.scalariform.NoWhitespaceAfterLeftBracketChecker"
           enabled="false"></check>

    <!-- This breaks symbolic method names so we don't turn it on. -->
    <!-- Maybe we should update it to allow basic symbolic names, and then we are good to go. -->
    <check level="error" class="org.scalastyle.scalariform.MethodNamesChecker" enabled="false">
        <parameters>
            <parameter name="regex"><![CDATA[^[a-z][A-Za-z0-9]*$]]></parameter>
        </parameters>
    </check>

    <!-- Should turn this on, but we have a few places that need to be fixed first -->
    <check level="error" class="org.scalastyle.scalariform.EqualsHashCodeChecker"
           enabled="true"></check>

    <!-- ================================================================================ -->
    <!--                               rules we don't want                                -->
    <!-- ================================================================================ -->

    <check level="error" class="org.scalastyle.scalariform.IllegalImportsChecker" enabled="false">
        <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>

    <!-- This one complains about all kinds of random things. Disable. -->
    <check level="error" class="org.scalastyle.scalariform.SimplifyBooleanExpressionChecker"
           enabled="false"></check>

    <!-- We use return quite a bit for control flows and guards -->
    <check level="error" class="org.scalastyle.scalariform.ReturnChecker" enabled="false"></check>

    <!-- We use null a lot in low level code and to interface with 3rd party code -->
    <check level="error" class="org.scalastyle.scalariform.NullChecker" enabled="false"></check>

    <!-- Doesn't seem super big deal here ... -->
    <check level="error" class="org.scalastyle.scalariform.NoCloneChecker" enabled="false"></check>

    <!-- Doesn't seem super big deal here ... -->
    <check level="error" class="org.scalastyle.file.FileLengthChecker" enabled="false">
        <parameters>
            <parameter name="maxFileLength">800></parameter>
        </parameters>
    </check>

    <!-- Doesn't seem super big deal here ... -->
    <check level="error" class="org.scalastyle.scalariform.NumberOfTypesChecker" enabled="false">
        <parameters>
            <parameter name="maxTypes">30</parameter>
        </parameters>
    </check>

    <!-- Doesn't seem super big deal here ... -->
    <check level="error" class="org.scalastyle.scalariform.CyclomaticComplexityChecker"
           enabled="false">
        <parameters>
            <parameter name="maximum">10</parameter>
        </parameters>
    </check>

    <!-- Doesn't seem super big deal here ... -->
    <check level="error" class="org.scalastyle.scalariform.MethodLengthChecker" enabled="false">
        <parameters>
            <parameter name="maxLength">50</parameter>
        </parameters>
    </check>

    <!-- Not exactly feasible to enforce this right now. -->
    <!-- It is also infrequent that somebody introduces a new class with a lot of methods. -->
    <check level="error" class="org.scalastyle.scalariform.NumberOfMethodsInTypeChecker"
           enabled="false">
        <parameters>
            <parameter name="maxMethods"><![CDATA[30]]></parameter>
        </parameters>
    </check>

    <!-- Doesn't seem super big deal here, and we have a lot of magic numbers ... -->
    <check level="error" class="org.scalastyle.scalariform.MagicNumberChecker" enabled="false">
        <parameters>
            <parameter name="ignore">-1,0,1,2,3</parameter>
        </parameters>
    </check>

</scalastyle>