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

Class ModifiedControlVariableCheck

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.ModifiedControlVariableCheck
All Implemented Interfaces:
Configurable, Contextualizable
public final class ModifiedControlVariableCheck extends AbstractCheck
Checks that for loop control variables are not modified inside the for block. An example is: 
 for (int i = 0; i < 1; i++) {
   i++; // violation
 }

Rationale: If the control variable is modified inside the loop body, the program flow becomes more difficult to follow. See FOR statement specification for more details.

Such loop would be suppressed: 

 for (int i = 0; i < 10;) {
   i++;
 }

NOTE:The check works with only primitive type variables. The check will not work for arrays used as control variable.An example is 

 for (int a[]={0};a[0] < 10;a[0]++) {
  a[0]++;   // it will skip this violation
 }
  • Property skipEnhancedForLoopVariable - Control whether to check enhanced for-loop variable. Type is boolean. Default value is false.

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

  • modified.control.variable
Since:
3.5

  • Field Details

  • Constructor Details

  • Method Details

    • setSkipEnhancedForLoopVariable

      public void setSkipEnhancedForLoopVariable(boolean skipEnhancedForLoopVariable)
      Setter to control whether to check enhanced for-loop variable.
      Parameters:
      skipEnhancedForLoopVariable - whether to skip enhanced for-loop variable
      Since:
      6.8

    • 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:

    • 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:

    • 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:

    • 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

    • leaveToken

      public void leaveToken(DetailAST ast)
      Description copied from class: AbstractCheck
      Called after all the child nodes have been process.
      Overrides:
      leaveToken in class AbstractCheck
      Parameters:
      ast - the token leaving

    • enterBlock

      private void enterBlock()
      Enters an inner class, which requires a new variable set.

    • exitBlock

      private void exitBlock()
      Leave an inner class, so restore variable set.

    • getCurrentVariables

      private Deque<String> getCurrentVariables()
      Get current variable stack.
      Returns:
      current variable stack

    • checkIdent

      private void checkIdent(DetailAST ast)
      Check if ident is parameter.
      Parameters:
      ast - ident to check.

    • leaveForIter

      private void leaveForIter(DetailAST ast)
      Push current variables to the stack.
      Parameters:
      ast - a for definition.

    • getVariablesManagedByForLoop

      private static Set<String> getVariablesManagedByForLoop(DetailAST ast)
      Determines which variable are specific to for loop and should not be change by inner loop body.
      Parameters:
      ast - For Loop
      Returns:
      Set of Variable Name which are managed by for

    • leaveForEach

      private void leaveForEach(DetailAST paramDef)
      Push current variables to the stack.
      Parameters:
      paramDef - a for-each clause variable

    • leaveForDef

      private void leaveForDef(DetailAST ast)
      Pops the variables from the stack.
      Parameters:
      ast - a for definition.

    • popCurrentVariables

      private void popCurrentVariables(int count)
      Pops given number of variables from currentVariables.
      Parameters:
      count - Count of variables to be popped from currentVariables

    • getForInitVariables

      private static Set<String> getForInitVariables(DetailAST ast)
      Get all variables initialized In init part of for loop.
      Parameters:
      ast - for loop token
      Returns:
      set of variables initialized in for loop

    • getForIteratorVariables

      private static Set<String> getForIteratorVariables(DetailAST ast)
      Get all variables which for loop iterating part change in every loop.
      Parameters:
      ast - for loop literal(TokenTypes.LITERAL_FOR)
      Returns:
      names of variables change in iterating part of for

    • findChildrenOfExpressionType

      private static List<DetailAST> findChildrenOfExpressionType(DetailAST ast)
      Find all child of given AST of type TokenType.EXPR.
      Parameters:
      ast - parent of expressions to find
      Returns:
      all child of given ast