checkstyle.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  ~ Copyright (C) 2015 Google Inc.
  ~
  ~ 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.
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-->
<!DOCTYPE module PUBLIC
    "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
    "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">

<!-- This is a checkstyle configuration file. For descriptions of
what the following rules do, please see the checkstyle configuration
page at http://checkstyle.sourceforge.net/config.html -->

<module name="Checker">

  <module name="RegexpSingleline">
    <!-- Requires a Google copyright notice in each file.
      Code intended to be open-sourced may have a multi-line copyright
      notice, so that this required text appears on the second line:
      <pre>
        /*
         * Copyright 2015 Google Inc.
         *
         * (details of open-source license...)
      </pre>
    -->
    <property name="format"
        value="^(//| \*) Copyright (\([cC]\) )?[\d]{4}(\-[\d]{4})? (Google Inc\.|The Google Cloud Dataflow.*Authors).*$" />
    <property name="minimum" value="1" />
    <property name="maximum" value="10" />
    <property name="message" value="Google copyright is missing or malformed." />
    <property name="severity" value="error" />
  </module>

  <module name="FileTabCharacter">
    <!-- Checks that there are no tab characters in the file. -->
  </module>

  <module name="NewlineAtEndOfFile"/>

  <module name="RegexpSingleline">
    <!-- Checks that TODOs don't have stuff in parenthesis, e.g., username. -->
    <property name="format" value="((//.*)|(\*.*))TODO\(" />
    <property name="message" value="TODO comments must not include usernames." />
    <property name="severity" value="error" />
  </module>

  <module name="RegexpSingleline">
    <property name="format" value="[ \t]+$"/>
    <property name="message" value="Trailing whitespace"/>
    <property name="severity" value="error"/>
  </module>

  <module name="RegexpSingleline">
    <!-- Checks that FIXME is not used in comments.  -->
    <property name="format" value="((//.*)|(\*.*))FIXME" />
    <property name="message" value='FIXME should not appear in comments.' />
    <property name="severity" value="error"/>
  </module>

  <module name="RegexpSingleline">
    <!-- Checks that XXX is not used in comments.  -->
    <property name="format" value="((//.*)|(\*.*))XXX" />
    <property name="message" value='XXX should not appear in comments.' />
    <property name="severity" value="error"/>
  </module>

  <module name="RegexpSingleline">
    <!-- Checks that Throwables.propagate is not used.  -->
    <property name="format" value="Throwables.propagate\(" />
    <property name="message" value='Throwables.propagate is deprecated.' />
    <property name="severity" value="error"/>
  </module>

  <!-- Allow use of comment to suppress javadocstyle -->
  <module name="SuppressionCommentFilter">
    <property name="offCommentFormat" value="CHECKSTYLE.OFF\: ([\w\|]+)"/>
    <property name="onCommentFormat" value="CHECKSTYLE.ON\: ([\w\|]+)"/>
    <property name="checkFormat" value="$1"/>
  </module>

  <!-- All Java AST specific tests live under TreeWalker module. -->
  <module name="TreeWalker">

    <module name="TodoComment">
      <metadata name="com.atlassw.tools.eclipse.checkstyle.comment"
                value="Author tags not allowed"/>
      <property name="format" value="@author"/>
      <property name="severity" value="error"/>
    </module>

    <!--

    IMPORT CHECKS

    -->

    <module name="RedundantImport">
      <!-- Checks for redundant import statements. -->
      <property name="severity" value="error"/>
      <message key="import.redundancy"
               value="Redundant import {0}."/>
    </module>

    <module name="ImportOrder">
      <!-- Checks for out of order import statements. -->

      <property name="severity" value="error"/>
      <property name="groups" value="com.google,android,com,io,Jama,junit,net,org,sun,java,javax"/>
      <!-- This ensures that static imports go first. -->
      <property name="option" value="top"/>
      <property name="tokens" value="STATIC_IMPORT, IMPORT"/>
      <message key="import.ordering"
               value="Import {0} appears after other imports that it should precede"/>
    </module>

    <module name="AvoidStarImport">
      <property name="severity" value="error"/>
    </module>

    <module name="IllegalImport">
      <property name="illegalPkgs" value="avro.shaded, com.google.api.client.repackaged, com.google.appengine.repackaged, org.apache.beam"/>
    </module>

    <module name="RedundantModifier">
      <!-- Checks for redundant modifiers on various symbol definitions.
        See: http://checkstyle.sourceforge.net/config_modifier.html#RedundantModifier
      -->
      <property name="tokens" value="METHOD_DEF, VARIABLE_DEF, ANNOTATION_FIELD_DEF, INTERFACE_DEF, CLASS_DEF, ENUM_DEF"/>
    </module>

    <!--
        IllegalImport cannot blacklist classes, and c.g.api.client.util is used for some shaded
        code and some useful code. So we need to fall back to Regexp.
    -->
    <module name="RegexpSinglelineJava">
      <property name="format" value="com\.google\.api\.client\.util\.(ByteStreams|Charsets|Collections2|Joiner|Lists|Maps|Objects|Preconditions|Sets|Strings|Throwables)"/>
    </module>

    <!-- Require static importing from Preconditions. -->
    <module name="RegexpSinglelineJava">
      <property name="format" value="^import com.google.common.base.Preconditions;$"/>
      <property name="message" value="Static import functions from Guava Preconditions"/>
    </module>

    <module name="UnusedImports">
      <property name="severity" value="error"/>
      <property name="processJavadoc" value="true"/>
      <message key="import.unused"
               value="Unused import: {0}."/>
    </module>

    <!--

    JAVADOC CHECKS

    -->

    <!-- Checks for Javadoc comments.                     -->
    <!-- See http://checkstyle.sf.net/config_javadoc.html -->
    <module name="JavadocMethod">
      <property name="scope" value="protected"/>
      <property name="severity" value="error"/>
      <property name="allowMissingJavadoc" value="true"/>
      <property name="allowMissingParamTags" value="true"/>
      <property name="allowMissingReturnTag" value="true"/>
      <property name="allowMissingThrowsTags" value="true"/>
      <property name="allowThrowsTagsForSubclasses" value="true"/>
      <property name="allowUndeclaredRTE" value="true"/>
    </module>

    <!-- Check that paragraph tags are used correctly in Javadoc. -->
    <module name="JavadocParagraph"/>

    <module name="JavadocType">
      <property name="scope" value="protected"/>
      <property name="severity" value="error"/>
      <property name="allowMissingParamTags" value="true"/>
    </module>

    <module name="JavadocStyle">
      <property name="severity" value="error"/>
      <property name="checkHtml" value="true"/>
    </module>

    <!--

    NAMING CHECKS

    -->

    <!-- Item 38 - Adhere to generally accepted naming conventions -->

    <module name="PackageName">
      <!-- Validates identifiers for package names against the
        supplied expression. -->
      <!-- Here the default checkstyle rule restricts package name parts to
        seven characters, this is not in line with common practice at Google.
      -->
      <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]{1,})*$"/>
      <property name="severity" value="error"/>
    </module>

    <module name="TypeNameCheck">
      <!-- Validates static, final fields against the
      expression "^[A-Z][a-zA-Z0-9]*$". -->
      <metadata name="altname" value="TypeName"/>
      <property name="severity" value="error"/>
    </module>

    <module name="ConstantNameCheck">
      <!-- Validates non-private, static, final fields against the supplied
      public/package final fields "^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$". -->
      <metadata name="altname" value="ConstantName"/>
      <property name="applyToPublic" value="true"/>
      <property name="applyToProtected" value="true"/>
      <property name="applyToPackage" value="true"/>
      <property name="applyToPrivate" value="false"/>
      <property name="format" value="^([A-Z][A-Z0-9]*(_[A-Z0-9]+)*|FLAG_.*)$"/>
      <message key="name.invalidPattern"
               value="Variable ''{0}'' should be in ALL_CAPS (if it is a constant) or be private (otherwise)."/>
      <property name="severity" value="error"/>
    </module>

    <module name="StaticVariableNameCheck">
      <!-- Validates static, non-final fields against the supplied
      expression "^[a-z][a-zA-Z0-9]*_?$". -->
      <metadata name="altname" value="StaticVariableName"/>
      <property name="applyToPublic" value="true"/>
      <property name="applyToProtected" value="true"/>
      <property name="applyToPackage" value="true"/>
      <property name="applyToPrivate" value="true"/>
      <property name="format" value="^[a-z][a-zA-Z0-9]*_?$"/>
      <property name="severity" value="error"/>
    </module>

    <module name="MemberNameCheck">
      <!-- Validates non-static members against the supplied expression. -->
      <metadata name="altname" value="MemberName"/>
      <property name="applyToPublic" value="true"/>
      <property name="applyToProtected" value="true"/>
      <property name="applyToPackage" value="true"/>
      <property name="applyToPrivate" value="true"/>
      <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
      <property name="severity" value="error"/>
    </module>

    <module name="MethodNameCheck">
      <!-- Validates identifiers for method names. -->
      <metadata name="altname" value="MethodName"/>
      <property name="format" value="^[a-z][a-zA-Z0-9]*(_[a-zA-Z0-9]+)*$"/>
      <property name="severity" value="error"/>
    </module>

    <module name="ParameterName">
      <!-- Validates identifiers for method parameters against the
        expression "^[a-z][a-zA-Z0-9]*$". -->
      <property name="severity" value="error"/>
    </module>

    <module name="LocalFinalVariableName">
      <!-- Validates identifiers for local final variables against the
        expression "^[a-z][a-zA-Z0-9]*$". -->
      <property name="severity" value="error"/>
    </module>

    <module name="LocalVariableName">
      <!-- Validates identifiers for local variables against the
        expression "^[a-z][a-zA-Z0-9]*$". -->
      <property name="severity" value="error"/>
    </module>

    <!-- Type parameters must be either one of the four blessed letters
    T, K, V, W, X or else be capital-case terminated with a T,
    such as MyGenericParameterT -->
    <module name="ClassTypeParameterName">
      <property name="format" value="^(((T|K|V|W|X)[0-9]*)|([A-Z][a-z][a-zA-Z]*T))$"/>
      <property name="severity" value="error"/>
    </module>

    <module name="MethodTypeParameterName">
      <property name="format" value="^(((T|K|V|W|X)[0-9]*)|([A-Z][a-z][a-zA-Z]*T))$"/>
      <property name="severity" value="error"/>
    </module>

    <module name="InterfaceTypeParameterName">
      <property name="format" value="^(((T|K|V|W|X)[0-9]*)|([A-Z][a-z][a-zA-Z]*T))$"/>
      <property name="severity" value="error"/>
    </module>

    <!--

    LENGTH and CODING CHECKS

    -->

    <module name="LineLength">
      <!-- Checks if a line is too long. -->
      <property name="max" value="${com.puppycrawl.tools.checkstyle.checks.sizes.LineLength.max}" default="100"/>
      <property name="severity" value="error"/>

      <!--
        The default ignore pattern exempts the following elements:
          - import statements
          - long URLs inside comments
      -->

      <property name="ignorePattern"
          value="${com.puppycrawl.tools.checkstyle.checks.sizes.LineLength.ignorePattern}"
          default="^(package .*;\s*)|(import .*;\s*)|( *\* .*https?://.*)$"/>
    </module>

    <module name="LeftCurly">
      <!-- Checks for placement of the left curly brace ('{'). -->
      <property name="severity" value="error"/>
    </module>

    <module name="RightCurly">
      <!-- Checks right curlies on CATCH, ELSE, and TRY blocks are on
      the same line. e.g., the following example is fine:
      <pre>
        if {
          ...
        } else
      </pre>
      -->
      <!-- This next example is not fine:
      <pre>
        if {
          ...
        }
        else
      </pre>
      -->
      <property name="option" value="same"/>
      <property name="severity" value="error"/>
    </module>

    <!-- Checks for braces around if and else blocks -->
    <module name="NeedBraces">
      <property name="severity" value="error"/>
      <property name="tokens" value="LITERAL_IF, LITERAL_ELSE, LITERAL_FOR, LITERAL_WHILE, LITERAL_DO"/>
    </module>

    <module name="UpperEll">
      <!-- Checks that long constants are defined with an upper ell.-->
      <property name="severity" value="error"/>
    </module>

    <module name="FallThrough">
      <!-- Warn about falling through to the next case statement.  Similar to
      javac -Xlint:fallthrough, but the check is suppressed if a single-line comment
      on the last non-blank line preceding the fallen-into case contains 'fall through' (or
      some other variants that we don't publicized to promote consistency).
      -->
      <property name="reliefPattern"
       value="fall through|Fall through|fallthru|Fallthru|falls through|Falls through|fallthrough|Fallthrough|No break|NO break|no break|continue on"/>
      <property name="severity" value="error"/>
    </module>


    <!--

    MODIFIERS CHECKS

    -->

    <module name="ModifierOrder">
      <!-- Warn if modifier order is inconsistent with JLS3 8.1.1, 8.3.1, and
           8.4.3.  The prescribed order is:
           public, protected, private, abstract, static, final, transient, volatile,
           synchronized, native, strictfp
        -->
      <property name="severity" value="error"/>
    </module>


    <!--

    WHITESPACE CHECKS

    -->

    <module name="WhitespaceAround">
      <!-- Checks that various tokens are surrounded by whitespace.
           This includes most binary operators and keywords followed
           by regular or curly braces.
      -->
      <property name="tokens" value="ASSIGN, BAND, BAND_ASSIGN, BOR,
        BOR_ASSIGN, BSR, BSR_ASSIGN, BXOR, BXOR_ASSIGN, COLON, DIV, DIV_ASSIGN,
        EQUAL, GE, GT, LAND, LE, LITERAL_CATCH, LITERAL_DO, LITERAL_ELSE,
        LITERAL_FINALLY, LITERAL_FOR, LITERAL_IF, LITERAL_RETURN,
        LITERAL_SYNCHRONIZED, LITERAL_TRY, LITERAL_WHILE, LOR, LT, MINUS,
        MINUS_ASSIGN, MOD, MOD_ASSIGN, NOT_EQUAL, PLUS, PLUS_ASSIGN, QUESTION,
        SL, SL_ASSIGN, SR_ASSIGN, STAR, STAR_ASSIGN"/>
      <property name="severity" value="error"/>
    </module>

    <module name="WhitespaceAfter">
      <!-- Checks that commas, semicolons and typecasts are followed by
           whitespace.
      -->
      <property name="tokens" value="COMMA, SEMI, TYPECAST"/>
    </module>

    <module name="NoWhitespaceAfter">
      <!-- Checks that there is no whitespace after various unary operators.
           Linebreaks are allowed.
      -->
      <property name="tokens" value="BNOT, DEC, DOT, INC, LNOT, UNARY_MINUS,
        UNARY_PLUS"/>
      <property name="allowLineBreaks" value="true"/>
      <property name="severity" value="error"/>
    </module>

    <module name="NoWhitespaceBefore">
      <!-- Checks that there is no whitespace before various unary operators.
           Linebreaks are allowed.
      -->
      <property name="tokens" value="SEMI, DOT, POST_DEC, POST_INC"/>
      <property name="allowLineBreaks" value="true"/>
      <property name="severity" value="error"/>
    </module>

    <module name="OperatorWrap">
      <!-- Checks that operators like + and ? appear at newlines rather than
           at the end of the previous line.
      -->
      <property name="option" value="NL"/>
      <property name="tokens" value="BAND, BOR, BSR, BXOR, DIV, EQUAL,
        GE, GT, LAND, LE, LITERAL_INSTANCEOF, LOR, LT, MINUS, MOD,
        NOT_EQUAL, PLUS, QUESTION, SL, SR, STAR "/>
    </module>

    <module name="ParenPad">
      <!-- Checks that there is no whitespace before close parens or after
           open parens.
      -->
      <property name="severity" value="error"/>
    </module>

    <!-- Required to support SuppressWarningsComment -->
    <module name="FileContentsHolder"/>

  </module>
</module>