Class ModifiedControlVariableCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable

    public final class ModifiedControlVariableCheck
    extends AbstractCheck
    Check for ensuring 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.

    Examples:

     <module name="ModifiedControlVariable">
     </module>
     

    Such loop would be suppressed:

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

    By default, This Check validates Enhanced For-Loop.

    Option 'skipEnhancedForLoopVariable' could be used to skip check of variable from Enhanced For Loop.

    An example of how to configure the check so that it skips enhanced For Loop Variable is:

     <module name="ModifiedControlVariable">
         <property name="skipEnhancedForLoopVariable" value="true"/>
     </module>
     

    Example:

     
     for (String line: lines) {
         line = line.trim();   // it will skip this violation
     }
     
     
    • 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
      • ILLEGAL_TYPE_OF_TOKEN

        private static final java.lang.String ILLEGAL_TYPE_OF_TOKEN
        Message thrown with IllegalStateException.
        See Also:
        Constant Field Values
      • MUTATION_OPERATIONS

        private static final java.util.Set<java.lang.Integer> MUTATION_OPERATIONS
        Operations which can change control variable in update part of the loop.
      • variableStack

        private final java.util.Deque<java.util.Deque<java.lang.String>> variableStack
        Stack of block parameters.
      • skipEnhancedForLoopVariable

        private boolean skipEnhancedForLoopVariable
        Controls whether to skip enhanced for-loop variable.
    • Constructor Detail

      • ModifiedControlVariableCheck

        public ModifiedControlVariableCheck()
    • Method Detail

      • setSkipEnhancedForLoopVariable

        public void setSkipEnhancedForLoopVariable​(boolean skipEnhancedForLoopVariable)
        Whether to skip enhanced for-loop variable or not.
        Parameters:
        skipEnhancedForLoopVariable - whether to skip enhanced for-loop variable
      • 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
      • 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
      • 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
      • 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
      • 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 java.util.Deque<java.lang.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 java.util.Set<java.lang.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 java.util.Set<java.lang.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 java.util.Set<java.lang.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 java.util.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