Package com.puppycrawl.tools.checkstyle.checks.regexp

Class RegexpMultilineCheck

java.lang.Object
com.puppycrawl.tools.checkstyle.api.AutomaticBean
com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck
com.puppycrawl.tools.checkstyle.checks.regexp.RegexpMultilineCheck
All Implemented Interfaces:
Configurable, Contextualizable, FileSetCheck
public class RegexpMultilineCheck extends AbstractFileSetCheck

Checks that a specified pattern matches across multiple lines in any file type.

Rationale: This check can be used to when the regular expression can be span multiple lines.

  • Property format - Specify the format of the regular expression to match. Type is java.util.regex.Pattern. Default value is "$.".
  • Property message - Specify the message which is used to notify about violations, if empty then default (hard-coded) message is used. Type is java.lang.String. Default value is null.
  • Property ignoreCase - Control whether to ignore case when searching. Type is boolean. Default value is false.
  • Property minimum - Specify the minimum number of matches required in each file. Type is int. Default value is 0.
  • Property maximum - Specify the maximum number of matches required in each file. Type is int. Default value is 0.
  • Property matchAcrossLines - Control whether to match expressions across multiple lines. Type is boolean. Default value is false.
  • Property fileExtensions - Specify the file type extension of files to process. Type is java.lang.String[]. Default value is "".

To run the check with its default configuration (no matches will be): 

 <module name="RegexpMultiline"/>

Example: 

 void method() {
   int i = 5; // OK
   System.out.println(i); // OK
 }

To configure the check to find calls to print to the console: 

 <module name="RegexpMultiline">
   <property name="format" value="System\.(out)|(err)\.print(ln)?\("/>
 </module>

Example: 

 void method() {
   System.out.print("Example");   // violation
   System.err.println("Example"); // violation
   System.out.print
     ("Example");                 // violation
   System.err.println
     ("Example");          // OK
   System
   .out.print("Example");  // OK
   System
   .err.println("Example");       // violation
   System.
   out.print("Example");   // OK
   System.
   err.println("Example");        // violation
 }

To configure the check to match text that spans multiple lines, like normal code in a Java file: 

 <module name="RegexpMultiline">
   <property name="matchAcrossLines" value="true"/>
   <property name="format" value="System\.out.*?print\("/>
 </module>

Example: 

 void method() {
   System.out.print("Example");  // violation
   System.err.println("Example");
   System.out.print              // violation
     ("Example");
   System.err.println
     ("Example");
   System
   .out.print("Example");
   System
   .err.println("Example");
   System.
   out.print("Example");
   System.
   err.println("Example");
 }

Note: Beware of the greedy regular expression used in the above example. .* will match as much as possible and not produce multiple violations in the file if multiple groups of lines could match the expression. To prevent an expression being too greedy, avoid overusing matching all text or allow it to be optional, like .*?. Changing the example expression to not be greedy will allow multiple violations in the example to be found in the same file.

To configure the check to match a maximum of three test strings: 

 <module name="RegexpMultiline">
   <property name="format" value="Test #[0-9]+:[A-Za-z ]+"/>
   <property name="ignoreCase" value="true"/>
   <property name="maximum" value="3"/>
 </module>

Example: 

 void method() {
   System.out.println("Test #1: this is a test string"); // OK
   System.out.println("TeSt #2: This is a test string"); // OK
   System.out.println("TEST #3: This is a test string"); // OK
   int i = 5;
   System.out.println("Value of i: " + i);
   System.out.println("Test #4: This is a test string"); // violation
   System.out.println("TEst #5: This is a test string"); // violation
 }

To configure the check to match a minimum of two test strings: 

 <module name="RegexpMultiline">
   <property name="format" value="Test #[0-9]+:[A-Za-z ]+"/>
   <property name="minimum" value="2"/>
 </module>

Example: 

 void method() {
   System.out.println("Test #1: this is a test string"); // violation
   System.out.println("TEST #2: This is a test string"); // OK, "ignoreCase" is false by default
   int i = 5;
   System.out.println("Value of i: " + i);
   System.out.println("Test #3: This is a test string"); // violation
   System.out.println("Test #4: This is a test string"); // violation
 }

To configure the check to restrict an empty file: 

 <module name="RegexpMultiline">
     <property name="format" value="^\s*$" />
     <property name="matchAcrossLines" value="true" />
     <property name="message" value="Empty file is not allowed" />
 </module>

Example of violation from the above config: 

 /var/tmp$ cat -n Test.java
 1
 2
 3
 4

Result:

 /var/tmp/Test.java // violation, a file must not be empty.

Parent is com.puppycrawl.tools.checkstyle.Checker

Violation Message Keys:

  • regexp.StackOverflowError
  • regexp.empty
  • regexp.exceeded
  • regexp.minimum
Since:
5.0

  • Field Details

    • format

      private String format
      Specify the format of the regular expression to match.

    • message

      private String message
      Specify the message which is used to notify about violations, if empty then default (hard-coded) message is used.

    • minimum

      private int minimum
      Specify the minimum number of matches required in each file.

    • maximum

      private int maximum
      Specify the maximum number of matches required in each file.

    • ignoreCase

      private boolean ignoreCase
      Control whether to ignore case when searching.

    • matchAcrossLines

      private boolean matchAcrossLines
      Control whether to match expressions across multiple lines.

    • detector

      private MultilineDetector detector
      The detector to use.

  • Constructor Details

    • RegexpMultilineCheck

      public RegexpMultilineCheck()

  • Method Details

    • beginProcessing

      public void beginProcessing(String charset)
      Description copied from interface: FileSetCheck
      Called when about to be called to process a set of files.
      Specified by:
      beginProcessing in interface FileSetCheck
      Overrides:
      beginProcessing in class AbstractFileSetCheck
      Parameters:
      charset - the character set used to read the files.

    • processFiltered

      protected void processFiltered(File file, FileText fileText)
      Description copied from class: AbstractFileSetCheck
      Called to process a file that matches the specified file extensions.
      Specified by:
      processFiltered in class AbstractFileSetCheck
      Parameters:
      file - the file to be processed
      fileText - the contents of the file.

    • getRegexCompileFlags

      private int getRegexCompileFlags()
      Retrieves the compile flags for the regular expression being built based on matchAcrossLines.
      Returns:
      The compile flags.

    • setFormat

      public void setFormat(String format)
      Setter to specify the format of the regular expression to match.
      Parameters:
      format - the format of the regular expression to match.

    • setMessage

      public void setMessage(String message)
      Setter to specify the message which is used to notify about violations, if empty then default (hard-coded) message is used.
      Parameters:
      message - the message to report for a match.

    • setMinimum

      public void setMinimum(int minimum)
      Setter to specify the minimum number of matches required in each file.
      Parameters:
      minimum - the minimum number of matches required in each file.

    • setMaximum

      public void setMaximum(int maximum)
      Setter to specify the maximum number of matches required in each file.
      Parameters:
      maximum - the maximum number of matches required in each file.

    • setIgnoreCase

      public void setIgnoreCase(boolean ignoreCase)
      Setter to control whether to ignore case when searching.
      Parameters:
      ignoreCase - whether to ignore case when searching.

    • setMatchAcrossLines

      public void setMatchAcrossLines(boolean matchAcrossLines)
      Setter to control whether to match expressions across multiple lines.
      Parameters:
      matchAcrossLines - whether to match expressions across multiple lines.