ModifiedControlVariableCheck (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.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.
To configure the check:
```
 <module name="ModifiedControlVariable"/>
 
```
Example:
```
 for(int i=0;i < 8;i++) {
   i++; // violation, control variable modified
 }
 String args1[]={"Coding", "block"};
 for (String arg: args1) {
   arg = arg.trim(); // violation, control variable modified
 }
 
```
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(int i=0;i < 8;i++) {
   i++; // violation, control variable modified
 }
 String args1[]={"Coding", "block"};
 for (String arg: args1) {
   arg = arg.trim(); // ok
 }
 
```
Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:
- modified.control.variable
Since:

3.5

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.lang.String`	`ILLEGAL_TYPE_OF_TOKEN` Message thrown with IllegalStateException.
`static java.lang.String`	`MSG_KEY` A key is pointing to the warning message text in "messages.properties" file.
`private static java.util.Set<java.lang.Integer>`	`MUTATION_OPERATIONS` Operations which can change control variable in update part of the loop.
`private boolean`	`skipEnhancedForLoopVariable` Control whether to check enhanced for-loop variable.
`private java.util.Deque<java.util.Deque<java.lang.String>>`	`variableStack` Stack of block parameters.

Constructor Summary

Constructors
Constructor and Description

ModifiedControlVariableCheck()

Constructors
Constructor and Description
`ModifiedControlVariableCheck()`

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 void`	`checkIdent(DetailAST ast)` Check if ident is parameter.
`private void`	`enterBlock()` Enters an inner class, which requires a new variable set.
`private void`	`exitBlock()` Leave an inner class, so restore variable set.
`private static java.util.List<DetailAST>`	`findChildrenOfExpressionType(DetailAST ast)` Find all child of given AST of type TokenType.EXPR
`int[]`	`getAcceptableTokens()` The configurable token set.
`private java.util.Deque<java.lang.String>`	`getCurrentVariables()` Get current variable stack.
`int[]`	`getDefaultTokens()` Returns the default token a check is interested in.
`private static java.util.Set<java.lang.String>`	`getForInitVariables(DetailAST ast)` Get all variables initialized In init part of for loop.
`private static java.util.Set<java.lang.String>`	`getForIteratorVariables(DetailAST ast)` Get all variables which for loop iterating part change in every loop.
`int[]`	`getRequiredTokens()` The tokens that this check must be registered for.
`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.
`private void`	`leaveForDef(DetailAST ast)` Pops the variables from the stack.
`private void`	`leaveForEach(DetailAST paramDef)` Push current variables to the stack.
`private void`	`leaveForIter(DetailAST ast)` Push current variables to the stack.
`void`	`leaveToken(DetailAST ast)` Called after all the child nodes have been process.
`private void`	`popCurrentVariables(int count)` Pops given number of variables from currentVariables.
`void`	`setSkipEnhancedForLoopVariable(boolean skipEnhancedForLoopVariable)` Setter to control whether to check enhanced for-loop variable.
`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, 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
  - 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
```
    Control whether to check enhanced for-loop variable.
- Constructor Detail
  - ModifiedControlVariableCheck
```
public ModifiedControlVariableCheck()
```
- Method Detail
  - 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
  - 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
  - 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 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

Class ModifiedControlVariableCheck

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

ILLEGAL_TYPE_OF_TOKEN

MUTATION_OPERATIONS

variableStack

skipEnhancedForLoopVariable

Constructor Detail

ModifiedControlVariableCheck

Method Detail

setSkipEnhancedForLoopVariable

getDefaultTokens

getRequiredTokens

getAcceptableTokens

beginTree

visitToken

leaveToken

enterBlock

exitBlock

getCurrentVariables

checkIdent

leaveForIter

getVariablesManagedByForLoop

leaveForEach

leaveForDef

popCurrentVariables

getForInitVariables

getForIteratorVariables

findChildrenOfExpressionType