Package com.puppycrawl.tools.checkstyle.checks.coding

Class VariableDeclarationUsageDistanceCheck

java.lang.Object
com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
com.puppycrawl.tools.checkstyle.api.AbstractCheck
com.puppycrawl.tools.checkstyle.checks.coding.VariableDeclarationUsageDistanceCheck
All Implemented Interfaces:
Configurable, Contextualizable
public class VariableDeclarationUsageDistanceCheck extends AbstractCheck
Checks the distance between declaration of variable and its first usage. Note : Variable declaration/initialization statements are not counted while calculating length.
  • Property allowedDistance - Specify distance between declaration of variable and its first usage. Values should be greater than 0. Type is int. Default value is 3.
  • Property ignoreFinal - Allow to ignore variables with a 'final' modifier. Type is boolean. Default value is true.
  • Property ignoreVariablePattern - Define RegExp to ignore distance calculation for variables listed in this pattern. Type is java.util.regex.Pattern. Default value is "".
  • Property validateBetweenScopes - Allow to calculate the distance between declaration of variable and its first usage in the different scopes. Type is boolean. Default value is false.

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

  • variable.declaration.usage.distance
  • variable.declaration.usage.distance.extend
Since:
5.8

  • Field Details

    • MSG_KEY

      public static final String MSG_KEY
      Warning message key.
      See Also:

    • MSG_KEY_EXT

      public static final String MSG_KEY_EXT
      Warning message key.
      See Also:

    • DEFAULT_DISTANCE

      private static final int DEFAULT_DISTANCE
      Default value of distance between declaration of variable and its first usage.
      See Also:

    • allowedDistance

      private int allowedDistance
      Specify distance between declaration of variable and its first usage. Values should be greater than 0.

    • ignoreVariablePattern

      private Pattern ignoreVariablePattern
      Define RegExp to ignore distance calculation for variables listed in this pattern.

    • validateBetweenScopes

      private boolean validateBetweenScopes
      Allow to calculate the distance between declaration of variable and its first usage in the different scopes.

    • ignoreFinal

      private boolean ignoreFinal
      Allow to ignore variables with a 'final' modifier.

  • Constructor Details

  • Method Details

    • setAllowedDistance

      public void setAllowedDistance(int allowedDistance)
      Setter to specify distance between declaration of variable and its first usage. Values should be greater than 0.
      Parameters:
      allowedDistance - Allowed distance between declaration of variable and its first usage.
      Since:
      5.8

    • setIgnoreVariablePattern

      public void setIgnoreVariablePattern(Pattern pattern)
      Setter to define RegExp to ignore distance calculation for variables listed in this pattern.
      Parameters:
      pattern - a pattern.
      Since:
      5.8

    • setValidateBetweenScopes

      public void setValidateBetweenScopes(boolean validateBetweenScopes)
      Setter to allow to calculate the distance between declaration of variable and its first usage in the different scopes.
      Parameters:
      validateBetweenScopes - Defines if allow to calculate distance between declaration of variable and its first usage in different scopes or not.
      Since:
      5.8

    • setIgnoreFinal

      public void setIgnoreFinal(boolean ignoreFinal)
      Setter to allow to ignore variables with a 'final' modifier.
      Parameters:
      ignoreFinal - Defines if ignore variables with 'final' modifier or not.
      Since:
      5.8

    • 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:

    • 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:

    • 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:

    • 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

    • getInstanceName

      private static String getInstanceName(DetailAST methodCallAst)
      Get name of instance whose method is called.
      Parameters:
      methodCallAst - DetailAST of METHOD_CALL.
      Returns:
      name of instance.

    • isInitializationSequence

      private static boolean isInitializationSequence(DetailAST variableUsageAst, String variableName)
      Processes statements until usage of variable to detect sequence of initialization methods.
      Parameters:
      variableUsageAst - DetailAST of expression that uses variable named variableName.
      variableName - name of considered variable.
      Returns:
      true if statements between declaration and usage of variable are initialization methods.

    • calculateDistanceInSingleScope

      private static Map.Entry<DetailAST,Integer> calculateDistanceInSingleScope(DetailAST semicolonAst, DetailAST variableIdentAst)
      Calculates distance between declaration of variable and its first usage in single scope.
      Parameters:
      semicolonAst - Regular node of Ast which is checked for content of checking variable.
      variableIdentAst - Variable which distance is calculated for.
      Returns:
      entry which contains expression with variable usage and distance. If variable usage is not found, then the expression node is null, although the distance can be greater than zero.

    • getDistToVariableUsageInChildNode

      private static int getDistToVariableUsageInChildNode(DetailAST childNode, int currentDistToVarUsage)
      Returns the distance to variable usage for in the child node.
      Parameters:
      childNode - child node.
      currentDistToVarUsage - current distance to the variable usage.
      Returns:
      the distance to variable usage for in the child node.

    • calculateDistanceBetweenScopes

      private static Map.Entry<DetailAST,Integer> calculateDistanceBetweenScopes(DetailAST ast, DetailAST variable)
      Calculates distance between declaration of variable and its first usage in multiple scopes.
      Parameters:
      ast - Regular node of Ast which is checked for content of checking variable.
      variable - Variable which distance is calculated for.
      Returns:
      entry which contains expression with variable usage and distance.

    • searchVariableUsageExpressions

      private static Map.Entry<List<DetailAST>,Integer> searchVariableUsageExpressions(DetailAST variableAst, DetailAST statementAst)
      Searches variable usages starting from specified statement.
      Parameters:
      variableAst - Variable that is used.
      statementAst - DetailAST to start searching from.
      Returns:
      entry which contains list with found expressions that use the variable and distance from specified statement to first found expression.

    • getFirstNodeInsideForWhileDoWhileBlocks

      private static DetailAST getFirstNodeInsideForWhileDoWhileBlocks(DetailAST block, DetailAST variable)
      Gets first Ast node inside FOR, WHILE or DO-WHILE blocks if variable usage is met only inside the block (not in its declaration!).
      Parameters:
      block - Ast node represents FOR, WHILE or DO-WHILE block.
      variable - Variable which is checked for content in block.
      Returns:
      If variable usage is met only inside the block (not in its declaration!) then return the first Ast node of this block, otherwise - null.

    • getFirstNodeInsideIfBlock

      private static DetailAST getFirstNodeInsideIfBlock(DetailAST block, DetailAST variable)
      Gets first Ast node inside IF block if variable usage is met only inside the block (not in its declaration!).
      Parameters:
      block - Ast node represents IF block.
      variable - Variable which is checked for content in block.
      Returns:
      If variable usage is met only inside the block (not in its declaration!) then return the first Ast node of this block, otherwise - null.

    • getFirstNodeInsideSwitchBlock

      private static DetailAST getFirstNodeInsideSwitchBlock(DetailAST block, DetailAST variable)
      Gets first Ast node inside SWITCH block if variable usage is met only inside the block (not in its declaration!).
      Parameters:
      block - Ast node represents SWITCH block.
      variable - Variable which is checked for content in block.
      Returns:
      If variable usage is met only inside the block (not in its declaration!) then return the first Ast node of this block, otherwise - null.

    • getVariableUsageExpressionsInsideSwitchBlock

      private static List<DetailAST> getVariableUsageExpressionsInsideSwitchBlock(DetailAST block, DetailAST variable)
      Helper method for getFirstNodeInsideSwitchBlock to return all variable usage expressions inside a given switch block.
      Parameters:
      block - the switch block to check.
      variable - variable which is checked for in switch block.
      Returns:
      List of usages or empty list if none are found.

    • getFirstNodeInsideTryCatchFinallyBlocks

      private static DetailAST getFirstNodeInsideTryCatchFinallyBlocks(DetailAST block, DetailAST variable)
      Gets first Ast node inside TRY-CATCH-FINALLY blocks if variable usage is met only inside the block (not in its declaration!).
      Parameters:
      block - Ast node represents TRY-CATCH-FINALLY block.
      variable - Variable which is checked for content in block.
      Returns:
      If variable usage is met only inside the block (not in its declaration!) then return the first Ast node of this block, otherwise - null.

    • isVariableInOperatorExpr

      private static boolean isVariableInOperatorExpr(DetailAST operator, DetailAST variable)
      Checks if variable is in operator declaration. For instance: 
       boolean b = true;
 if (b) {...}
      Variable 'b' is in declaration of operator IF.
      Parameters:
      operator - Ast node which represents operator.
      variable - Variable which is checked for content in operator.
      Returns:
      true if operator contains variable in its declaration, otherwise - false.

    • isChild

      private static boolean isChild(DetailAST parent, DetailAST ast)
      Checks if Ast node contains given element.
      Parameters:
      parent - Node of AST.
      ast - Ast element which is checked for content in Ast node.
      Returns:
      true if Ast element was found in Ast node, otherwise - false.

    • isVariableMatchesIgnorePattern

      private boolean isVariableMatchesIgnorePattern(String variable)
      Checks if entrance variable is contained in ignored pattern.
      Parameters:
      variable - Variable which is checked for content in ignored pattern.
      Returns:
      true if variable was found, otherwise - false.

    • isZeroDistanceToken

      private static boolean isZeroDistanceToken(int type)
      Check if the token should be ignored for distance counting. For example, 
           try (final AutoCloseable t = new java.io.StringReader(a);) {
     }
      final is a zero-distance token and should be ignored for distance counting. 
           class Table implements Comparator<Integer>{
     }
      An inner class may be defined. Both tokens implements and extends are zero-distance tokens. 
           public int method(Object b){
     }
      public is a modifier and zero-distance token. int is a type and zero-distance token.
      Parameters:
      type - Token type of the ast node.
      Returns:
      true if it should be ignored for distance counting, otherwise false.