Package com.puppycrawl.tools.checkstyle.checks.metrics

Class NPathComplexityCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable
    public final class NPathComplexityCheck
extends AbstractCheck
    Checks the npath complexity against a specified limit (default = 200). The npath metric computes the number of possible execution paths through a function. Similar to the cyclomatic complexity but also takes into account the nesting of conditional statements and multi-part boolean expressions.

    • 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

      • DEFAULT_MAX

        private static final int DEFAULT_MAX
        Default allowed complexity.
        See Also:
        Constant Field Values

      • INITIAL_VALUE

        private static final java.math.BigInteger INITIAL_VALUE
        The initial current value.

      • rangeValues

        private final java.util.Deque<java.math.BigInteger> rangeValues
        Stack of NP values for ranges.

      • expressionValues

        private final java.util.Deque<java.lang.Integer> expressionValues
        Stack of NP values for expressions.

      • isAfterValues

        private final java.util.Deque<java.lang.Boolean> isAfterValues
        Stack of belongs to range values for question operator.

      • processingTokenEnd

        private final NPathComplexityCheck.TokenEnd processingTokenEnd
        Range of the last processed expression. Used for checking that ternary operation which is a part of expression won't be processed for second time.

      • currentRangeValue

        private java.math.BigInteger currentRangeValue
        NP value for current range.

      • max

        private int max
        Threshold to report error for.

      • branchVisited

        private boolean branchVisited
        True, when branch is visited, but not leaved.

    • Constructor Detail

      • NPathComplexityCheck

        public NPathComplexityCheck()

    • Method Detail

      • setMax

        public void setMax​(int max)
        Set the maximum threshold allowed.
        Parameters:
        max - the maximum threshold

      • 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

      • 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

      • visitConditional

        private void visitConditional​(DetailAST ast,
                              int basicBranchingFactor)
        Visits if, while, do-while, for and switch tokens - all of them have expression in parentheses which is used for calculation.
        Parameters:
        ast - visited token.
        basicBranchingFactor - default number of branches added.

      • visitUnitaryOperator

        private void visitUnitaryOperator​(DetailAST ast,
                                  int basicBranchingFactor)
        Visits ternary operator (?:) and return tokens. They differ from those processed by visitConditional method in that their expression isn't bracketed.
        Parameters:
        ast - visited token.
        basicBranchingFactor - number of branches inherently added by this token.

      • leaveUnitaryOperator

        private void leaveUnitaryOperator()
        Leaves ternary operator (?:) and return tokens.

      • leaveConditional

        private void leaveConditional()
        Leaves while, do, for, if, ternary (?::), return or switch.

      • leaveBranch

        private void leaveBranch()
        Leaves else, default or case group tokens.

      • leaveMethodDef

        private void leaveMethodDef​(DetailAST ast)
        Process the end of a method definition.
        Parameters:
        ast - the token type representing the method definition

      • leaveAddingConditional

        private void leaveAddingConditional()
        Leaves catch.

      • pushValue

        private void pushValue​(java.lang.Integer expressionValue)
        Pushes the current range value on the range value stack. Pushes this token expression value on the expression value stack.
        Parameters:
        expressionValue - value of expression calculated for current token.

      • popValue

        private NPathComplexityCheck.Values popValue()
        Pops values from both stack of expression values and stack of range values.
        Returns:
        pair of head values from both of the stacks.

      • leaveMultiplyingConditional

        private void leaveMultiplyingConditional()
        Leaves try.

      • getLastToken

        private static DetailAST getLastToken​(DetailAST ast)
        Finds a leaf, which is the most distant from the root.
        Parameters:
        ast - the root of tree.
        Returns:
        the leaf.

      • countCaseTokens

        private static int countCaseTokens​(DetailAST ast)
        Counts number of case tokens subject to a case group token.
        Parameters:
        ast - case group token.
        Returns:
        number of case tokens.