AvoidEscapedUnicodeCharactersCheck (checkstyle 9.3 API)

java.lang.Object
- com.puppycrawl.tools.checkstyle.api.AutomaticBean
- - com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
  - - com.puppycrawl.tools.checkstyle.api.AbstractCheck
    - - com.puppycrawl.tools.checkstyle.checks.AvoidEscapedUnicodeCharactersCheck

All Implemented Interfaces:: Configurable, Contextualizable

public class AvoidEscapedUnicodeCharactersCheck
extends AbstractCheck

Restricts using Unicode escapes (such as \u221e). It is possible to allow using escapes for non-printable, control characters. Also, this check can be configured to allow using escapes if trail comment is present. By the option it is possible to allow using escapes if literal contains only them.

Property allowEscapesForControlCharacters - Allow use escapes for non-printable, control characters. Type is boolean. Default value is false.
Property allowByTailComment - Allow use escapes if trail comment is present. Type is boolean. Default value is false.
Property allowIfAllCharactersEscaped - Allow if all characters in literal are escaped. Type is boolean. Default value is false.
Property allowNonPrintableEscapes - Allow use escapes for non-printable, whitespace characters. Type is boolean. Default value is false.

To configure the check:

 <module name="AvoidEscapedUnicodeCharacters"/>

Examples of using Unicode:

 String unitAbbrev = "μs";     // OK, perfectly clear even without a comment.
 String unitAbbrev = "\u03bcs";// violation, the reader has no idea what this is.
 return '\ufeff' + content;    // OK, an example of non-printable,
                               // control characters (byte order mark).

An example of how to configure the check to allow using escapes for non-printable, control characters:

 <module name="AvoidEscapedUnicodeCharacters">
   <property name="allowEscapesForControlCharacters" value="true"/>
 </module>

Example of using escapes for non-printable, control characters:

 String unitAbbrev = "μs";      // OK, a normal String
 String unitAbbrev = "\u03bcs"; // violation, "\u03bcs" is a printable character.
 return '\ufeff' + content;     // OK, non-printable control character.

An example of how to configure the check to allow using escapes if trail comment is present:

 <module name="AvoidEscapedUnicodeCharacters">
   <property name="allowByTailComment" value="true"/>
 </module>

Example of using escapes if trail comment is present:

 String unitAbbrev = "μs";      // OK, a normal String
 String unitAbbrev = "\u03bcs"; // OK, Greek letter mu, "s"
 return '\ufeff' + content;
 // -----^--------------------- violation, comment is not used within same line.

An example of how to configure the check to allow if all characters in literal are escaped.

 <module name="AvoidEscapedUnicodeCharacters">
   <property name="allowIfAllCharactersEscaped" value="true"/>
 </module>

Example of using escapes if all characters in literal are escaped:

 String unitAbbrev = "μs";      // OK, a normal String
 String unitAbbrev = "\u03bcs"; // violation, not all characters are escaped ('s').
 String unitAbbrev = "\u03bc\u03bc\u03bc"; // OK
 String unitAbbrev = "\u03bc\u03bcs";// violation, not all characters are escaped ('s').
 return '\ufeff' + content;          // OK, all control characters are escaped

An example of how to configure the check to allow using escapes for non-printable whitespace characters:

 <module name="AvoidEscapedUnicodeCharacters">
   <property name="allowNonPrintableEscapes" value="true"/>
 </module>

Example of using escapes for non-printable whitespace characters:

 String unitAbbrev = "μs";       // OK, a normal String
 String unitAbbrev1 = "\u03bcs"; // violation, printable escape character.
 String unitAbbrev2 = "\u03bc\u03bc\u03bc"; // violation, printable escape character.
 String unitAbbrev3 = "\u03bc\u03bcs";// violation, printable escape character.
 return '\ufeff' + content;           // OK, non-printable escape character.

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

forbid.escaped.unicode.char

Since:: 5.8

Nested Class Summary
- Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
  AutomaticBean.OutputStreamOptions

Field Summary

Fields
Modifier and Type	Field and Description
`private static java.util.regex.Pattern`	`ALL_ESCAPED_CHARS` Regular expression for all escaped chars.
`private boolean`	`allowByTailComment` Allow use escapes if trail comment is present.
`private boolean`	`allowEscapesForControlCharacters` Allow use escapes for non-printable, control characters.
`private boolean`	`allowIfAllCharactersEscaped` Allow if all characters in literal are escaped.
`private boolean`	`allowNonPrintableEscapes` Allow use escapes for non-printable, whitespace characters.
`private java.util.Map<java.lang.Integer,java.util.List<TextBlock>>`	`blockComments` C style comments.
`private static java.util.regex.Pattern`	`ESCAPED_BACKSLASH` Regular expression for escaped backslash.
`static java.lang.String`	`MSG_KEY` A key is pointing to the warning message text in "messages.properties" file.
`private static java.util.regex.Pattern`	`NON_PRINTABLE_CHARS` Regular expression for non-printable unicode chars.
`private java.util.Map<java.lang.Integer,TextBlock>`	`singlelineComments` Cpp style comments.
`private static java.util.regex.Pattern`	`UNICODE_CONTROL` Regular expression Unicode control characters.
`private static java.util.regex.Pattern`	`UNICODE_REGEXP` Regular expression for Unicode chars.

Constructor Summary

Constructors
Constructor and Description

AvoidEscapedUnicodeCharactersCheck()

Constructors
Constructor and Description
`AvoidEscapedUnicodeCharactersCheck()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`beginTree(DetailAST rootAST)` Called before the starting to process a tree.
`private static int`	`countMatches(java.util.regex.Pattern pattern, java.lang.String target)` Count regexp matches into String literal.
`int[]`	`getAcceptableTokens()` The configurable token set.
`int[]`	`getDefaultTokens()` Returns the default token a check is interested in.
`int[]`	`getRequiredTokens()` The tokens that this check must be registered for.
`private boolean`	`hasTrailComment(DetailAST ast)` Check if trail comment is present after ast token.
`private static boolean`	`hasUnicodeChar(java.lang.String literal)` Checks if literal has Unicode chars.
`private boolean`	`isAllCharactersEscaped(java.lang.String literal)` Checks if all characters in String literal is escaped.
`private static boolean`	`isOnlyUnicodeValidChars(java.lang.String literal, java.util.regex.Pattern pattern)` Check if String literal contains Unicode control chars.
`private static boolean`	`isTrailingBlockComment(TextBlock comment, int... codePoints)` Whether the C style comment is trailing.
`void`	`setAllowByTailComment(boolean allow)` Setter to allow use escapes if trail comment is present.
`void`	`setAllowEscapesForControlCharacters(boolean allow)` Setter to allow use escapes for non-printable, control characters.
`void`	`setAllowIfAllCharactersEscaped(boolean allow)` Setter to allow if all characters in literal are escaped.
`void`	`setAllowNonPrintableEscapes(boolean allow)` Setter to allow use escapes for non-printable, whitespace characters.
`void`	`visitToken(DetailAST ast)` Called to process a token.

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
clearViolations, destroy, finishTree, getFileContents, getLine, getLineCodePoints, getLines, getTabWidth, getTokenNames, getViolations, init, isCommentNodesRequired, leaveToken, log, log, log, setFileContents, setTabWidth, setTokens

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
finishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverity

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
configure, contextualize, getConfiguration, setupChild

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - MSG_KEY
```
public static final java.lang.String MSG_KEY
```
    A key is pointing to the warning message text in "messages.properties" file.
    
    See Also:
    
    Constant Field Values
  - UNICODE_REGEXP
```
private static final java.util.regex.Pattern UNICODE_REGEXP
```
    Regular expression for Unicode chars.
  - UNICODE_CONTROL
```
private static final java.util.regex.Pattern UNICODE_CONTROL
```
    Regular expression Unicode control characters.
    
    See Also:
    
    Appendix:Control characters
  - ALL_ESCAPED_CHARS
```
private static final java.util.regex.Pattern ALL_ESCAPED_CHARS
```
    Regular expression for all escaped chars. See "EscapeSequence" at https://docs.oracle.com/javase/specs/jls/se15/html/jls-3.html#jls-3.10.7
  - ESCAPED_BACKSLASH
```
private static final java.util.regex.Pattern ESCAPED_BACKSLASH
```
    Regular expression for escaped backslash.
  - NON_PRINTABLE_CHARS
```
private static final java.util.regex.Pattern NON_PRINTABLE_CHARS
```
    Regular expression for non-printable unicode chars.
  - singlelineComments
```
private java.util.Map<java.lang.Integer,TextBlock> singlelineComments
```
    Cpp style comments.
  - blockComments
```
private java.util.Map<java.lang.Integer,java.util.List<TextBlock>> blockComments
```
    C style comments.
  - allowEscapesForControlCharacters
```
private boolean allowEscapesForControlCharacters
```
    Allow use escapes for non-printable, control characters.
  - allowByTailComment
```
private boolean allowByTailComment
```
    Allow use escapes if trail comment is present.
  - allowIfAllCharactersEscaped
```
private boolean allowIfAllCharactersEscaped
```
    Allow if all characters in literal are escaped.
  - allowNonPrintableEscapes
```
private boolean allowNonPrintableEscapes
```
    Allow use escapes for non-printable, whitespace characters.
- Constructor Detail
  - AvoidEscapedUnicodeCharactersCheck
```
public AvoidEscapedUnicodeCharactersCheck()
```
- Method Detail
  - setAllowEscapesForControlCharacters
```
public final void setAllowEscapesForControlCharacters(boolean allow)
```
    Setter to allow use escapes for non-printable, control characters.
    
    Parameters:
    
    allow - user's value.
  - setAllowByTailComment
```
public final void setAllowByTailComment(boolean allow)
```
    Setter to allow use escapes if trail comment is present.
    
    Parameters:
    
    allow - user's value.
  - setAllowIfAllCharactersEscaped
```
public final void setAllowIfAllCharactersEscaped(boolean allow)
```
    Setter to allow if all characters in literal are escaped.
    
    Parameters:
    
    allow - user's value.
  - setAllowNonPrintableEscapes
```
public final void setAllowNonPrintableEscapes(boolean allow)
```
    Setter to allow use escapes for non-printable, whitespace characters.
    
    Parameters:
    
    allow - user's value.
  - getDefaultTokens
```
public int[] getDefaultTokens()
```
    Description copied from class: AbstractCheck
    
    Returns the default token a check is interested in. Only used if the configuration for a check does not define the tokens.
    
    Specified by:
    
    getDefaultTokens in class AbstractCheck
    
    Returns:
    
    the default tokens
    
    See Also:
    
    TokenTypes
  - getAcceptableTokens
```
public int[] getAcceptableTokens()
```
    Description copied from class: AbstractCheck
    
    The configurable token set. Used to protect Checks against malicious users who specify an unacceptable token set in the configuration file. The default implementation returns the check's default tokens.
    
    Specified by:
    
    getAcceptableTokens in class AbstractCheck
    
    Returns:
    
    the token set this check is designed for.
    
    See Also:
    
    TokenTypes
  - getRequiredTokens
```
public int[] getRequiredTokens()
```
    Description copied from class: AbstractCheck
    
    The tokens that this check must be registered for.
    
    Specified by:
    
    getRequiredTokens in class AbstractCheck
    
    Returns:
    
    the token set this must be registered for.
    
    See Also:
    
    TokenTypes
  - beginTree
```
public void beginTree(DetailAST rootAST)
```
    Description copied from class: AbstractCheck
    
    Called before the starting to process a tree. Ideal place to initialize information that is to be collected whilst processing a tree.
    
    Overrides:
    
    beginTree in class AbstractCheck
    
    Parameters:
    
    rootAST - the root of the tree
  - visitToken
```
public void visitToken(DetailAST ast)
```
    Description copied from class: AbstractCheck
    
    Called to process a token.
    
    Overrides:
    
    visitToken in class AbstractCheck
    
    Parameters:
    
    ast - the token to process
  - hasUnicodeChar
```
private static boolean hasUnicodeChar(java.lang.String literal)
```
    Checks if literal has Unicode chars.
    
    Parameters:
    
    literal - String literal.
    
    Returns:
    
    true if literal has Unicode chars.
  - isOnlyUnicodeValidChars
```
private static boolean isOnlyUnicodeValidChars(java.lang.String literal,
                                               java.util.regex.Pattern pattern)
```
    Check if String literal contains Unicode control chars.
    
    Parameters:
    
    literal - String literal.
    
    pattern - RegExp for valid characters.
    
    Returns:
    
    true, if String literal contains Unicode control chars.
  - hasTrailComment
```
private boolean hasTrailComment(DetailAST ast)
```
    Check if trail comment is present after ast token.
    
    Parameters:
    
    ast - current token.
    
    Returns:
    
    true if trail comment is present after ast token.
  - isTrailingBlockComment
```
private static boolean isTrailingBlockComment(TextBlock comment,
                                              int... codePoints)
```
    Whether the C style comment is trailing.
    
    Parameters:
    
    comment - the comment to check.
    
    codePoints - the first line of the comment, in unicode code points
    
    Returns:
    
    true if the comment is trailing.
  - countMatches
```
private static int countMatches(java.util.regex.Pattern pattern,
                                java.lang.String target)
```
    Count regexp matches into String literal.
    
    Parameters:
    
    pattern - pattern.
    
    target - String literal.
    
    Returns:
    
    count of regexp matches.
  - isAllCharactersEscaped
```
private boolean isAllCharactersEscaped(java.lang.String literal)
```
    Checks if all characters in String literal is escaped.
    
    Parameters:
    
    literal - current literal.
    
    Returns:
    
    true if all characters in String literal is escaped.

Class AvoidEscapedUnicodeCharactersCheck

Nested Class Summary

Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

Field Summary

Constructor Summary

Method Summary

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

Methods inherited from class java.lang.Object

Field Detail

MSG_KEY

UNICODE_REGEXP

UNICODE_CONTROL

ALL_ESCAPED_CHARS

ESCAPED_BACKSLASH

NON_PRINTABLE_CHARS

singlelineComments

blockComments

allowEscapesForControlCharacters

allowByTailComment

allowIfAllCharactersEscaped

allowNonPrintableEscapes

Constructor Detail

AvoidEscapedUnicodeCharactersCheck

Method Detail

setAllowEscapesForControlCharacters

setAllowByTailComment

setAllowIfAllCharactersEscaped

setAllowNonPrintableEscapes

getDefaultTokens

getAcceptableTokens

getRequiredTokens

beginTree

visitToken

hasUnicodeChar

isOnlyUnicodeValidChars

hasTrailComment

isTrailingBlockComment

countMatches

isAllCharactersEscaped