////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2017 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
////////////////////////////////////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.metrics;
import java.math.BigInteger;
import java.util.ArrayDeque;
import java.util.Deque;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
/**
* 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.
*
* @author <a href="mailto:simon@redhillconsulting.com.au">Simon Harris</a>
* @author o_sukhodolsky
*/
// -@cs[AbbreviationAsWordInName] Can't change check name
public final class NPathComplexityCheck extends AbstractCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY = "npathComplexity";
/** Default allowed complexity. */
private static final int DEFAULT_MAX = 200;
/** The initial current value. */
private static final BigInteger INITIAL_VALUE = BigInteger.ZERO;
/**
* Stack of NP values for ranges.
*/
private final Deque<BigInteger> rangeValues = new ArrayDeque<>();
/** Stack of NP values for expressions. */
private final Deque<Integer> expressionValues = new ArrayDeque<>();
/** Stack of belongs to range values for question operator. */
private final Deque<Boolean> isAfterValues = new ArrayDeque<>();
/**
* 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.
*/
private final TokenEnd processingTokenEnd = new TokenEnd();
/** NP value for current range. */
private BigInteger currentRangeValue = INITIAL_VALUE;
/** Threshold to report error for. */
private int max = DEFAULT_MAX;
/** True, when branch is visited, but not leaved. */
private boolean branchVisited;
/**
* Set the maximum threshold allowed.
* @param max the maximum threshold
*/
public void setMax(int max) {
this.max = max;
}
@Override
public int[] getDefaultTokens() {
return getAcceptableTokens();
}
@Override
public int[] getAcceptableTokens() {
return new int[] {
TokenTypes.CTOR_DEF,
TokenTypes.METHOD_DEF,
TokenTypes.STATIC_INIT,
TokenTypes.INSTANCE_INIT,
TokenTypes.LITERAL_WHILE,
TokenTypes.LITERAL_DO,
TokenTypes.LITERAL_FOR,
TokenTypes.LITERAL_IF,
TokenTypes.LITERAL_ELSE,
TokenTypes.LITERAL_SWITCH,
TokenTypes.CASE_GROUP,
TokenTypes.LITERAL_TRY,
TokenTypes.LITERAL_CATCH,
TokenTypes.QUESTION,
TokenTypes.LITERAL_RETURN,
TokenTypes.LITERAL_DEFAULT,
};
}
@Override
public int[] getRequiredTokens() {
return getAcceptableTokens();
}
@Override
public void beginTree(DetailAST rootAST) {
rangeValues.clear();
expressionValues.clear();
isAfterValues.clear();
processingTokenEnd.reset();
currentRangeValue = INITIAL_VALUE;
branchVisited = false;
}
@Override
public void visitToken(DetailAST ast) {
switch (ast.getType()) {
case TokenTypes.LITERAL_IF:
case TokenTypes.LITERAL_SWITCH:
case TokenTypes.LITERAL_WHILE:
case TokenTypes.LITERAL_DO:
case TokenTypes.LITERAL_FOR:
visitConditional(ast, 1);
break;
case TokenTypes.QUESTION:
visitUnitaryOperator(ast, 2);
break;
case TokenTypes.LITERAL_RETURN:
visitUnitaryOperator(ast, 0);
break;
case TokenTypes.CASE_GROUP:
final int caseNumber = countCaseTokens(ast);
branchVisited = true;
pushValue(caseNumber);
break;
case TokenTypes.LITERAL_ELSE:
branchVisited = true;
if (currentRangeValue.equals(BigInteger.ZERO)) {
currentRangeValue = BigInteger.ONE;
}
pushValue(0);
break;
case TokenTypes.LITERAL_TRY:
case TokenTypes.LITERAL_CATCH:
case TokenTypes.LITERAL_DEFAULT:
pushValue(1);
break;
case TokenTypes.CTOR_DEF:
case TokenTypes.METHOD_DEF:
case TokenTypes.INSTANCE_INIT:
case TokenTypes.STATIC_INIT:
pushValue(0);
break;
default:
break;
}
}
@Override
public void leaveToken(DetailAST ast) {
switch (ast.getType()) {
case TokenTypes.LITERAL_WHILE:
case TokenTypes.LITERAL_DO:
case TokenTypes.LITERAL_FOR:
case TokenTypes.LITERAL_IF:
case TokenTypes.LITERAL_SWITCH:
leaveConditional();
break;
case TokenTypes.LITERAL_TRY:
leaveMultiplyingConditional();
break;
case TokenTypes.LITERAL_RETURN:
case TokenTypes.QUESTION:
leaveUnitaryOperator();
break;
case TokenTypes.LITERAL_CATCH:
leaveAddingConditional();
break;
case TokenTypes.LITERAL_DEFAULT:
leaveBranch();
break;
case TokenTypes.LITERAL_ELSE:
case TokenTypes.CASE_GROUP:
leaveBranch();
branchVisited = false;
break;
case TokenTypes.CTOR_DEF:
case TokenTypes.METHOD_DEF:
case TokenTypes.INSTANCE_INIT:
case TokenTypes.STATIC_INIT:
leaveMethodDef(ast);
break;
default:
break;
}
}
/**
* Visits if, while, do-while, for and switch tokens - all of them have expression in
* parentheses which is used for calculation.
* @param ast visited token.
* @param basicBranchingFactor default number of branches added.
*/
private void visitConditional(DetailAST ast, int basicBranchingFactor) {
int expressionValue = basicBranchingFactor;
DetailAST bracketed;
for (bracketed = ast.findFirstToken(TokenTypes.LPAREN).getNextSibling();
bracketed.getType() != TokenTypes.RPAREN;
bracketed = bracketed.getNextSibling()) {
expressionValue += countConditionalOperators(bracketed);
}
processingTokenEnd.setToken(bracketed);
pushValue(expressionValue);
}
/**
* Visits ternary operator (?:) and return tokens. They differ from those processed by
* visitConditional method in that their expression isn't bracketed.
* @param ast visited token.
* @param basicBranchingFactor number of branches inherently added by this token.
*/
private void visitUnitaryOperator(DetailAST ast, int basicBranchingFactor) {
final boolean isAfter = processingTokenEnd.isAfter(ast);
isAfterValues.push(isAfter);
if (!isAfter) {
processingTokenEnd.setToken(getLastToken(ast));
final int expressionValue = basicBranchingFactor + countConditionalOperators(ast);
pushValue(expressionValue);
}
}
/**
* Leaves ternary operator (?:) and return tokens.
*/
private void leaveUnitaryOperator() {
if (!isAfterValues.pop()) {
final Values valuePair = popValue();
BigInteger basicRangeValue = valuePair.getRangeValue();
BigInteger expressionValue = valuePair.getExpressionValue();
if (expressionValue.equals(BigInteger.ZERO)) {
expressionValue = BigInteger.ONE;
}
if (basicRangeValue.equals(BigInteger.ZERO)) {
basicRangeValue = BigInteger.ONE;
}
currentRangeValue = currentRangeValue.add(expressionValue).multiply(basicRangeValue);
}
}
/** Leaves while, do, for, if, ternary (?::), return or switch. */
private void leaveConditional() {
final Values valuePair = popValue();
final BigInteger expressionValue = valuePair.getExpressionValue();
BigInteger basicRangeValue = valuePair.getRangeValue();
if (currentRangeValue.equals(BigInteger.ZERO)) {
currentRangeValue = BigInteger.ONE;
}
if (basicRangeValue.equals(BigInteger.ZERO)) {
basicRangeValue = BigInteger.ONE;
}
currentRangeValue = currentRangeValue.add(expressionValue).multiply(basicRangeValue);
}
/** Leaves else, default or case group tokens. */
private void leaveBranch() {
final Values valuePair = popValue();
final BigInteger basicRangeValue = valuePair.getRangeValue();
final BigInteger expressionValue = valuePair.getExpressionValue();
if (branchVisited && currentRangeValue.equals(BigInteger.ZERO)) {
currentRangeValue = BigInteger.ONE;
}
currentRangeValue = currentRangeValue.subtract(BigInteger.ONE)
.add(basicRangeValue)
.add(expressionValue);
}
/**
* Process the end of a method definition.
* @param ast the token type representing the method definition
*/
private void leaveMethodDef(DetailAST ast) {
final BigInteger bigIntegerMax = BigInteger.valueOf(max);
if (currentRangeValue.compareTo(bigIntegerMax) > 0) {
log(ast, MSG_KEY, currentRangeValue, bigIntegerMax);
}
popValue();
currentRangeValue = INITIAL_VALUE;
}
/** Leaves catch. */
private void leaveAddingConditional() {
currentRangeValue = currentRangeValue.add(popValue().getRangeValue().add(BigInteger.ONE));
}
/**
* Pushes the current range value on the range value stack. Pushes this token expression value
* on the expression value stack.
* @param expressionValue value of expression calculated for current token.
*/
private void pushValue(Integer expressionValue) {
rangeValues.push(currentRangeValue);
expressionValues.push(expressionValue);
currentRangeValue = INITIAL_VALUE;
}
/**
* Pops values from both stack of expression values and stack of range values.
* @return pair of head values from both of the stacks.
*/
private Values popValue() {
final int expressionValue = expressionValues.pop();
return new Values(rangeValues.pop(), BigInteger.valueOf(expressionValue));
}
/** Leaves try. */
private void leaveMultiplyingConditional() {
currentRangeValue = currentRangeValue.add(BigInteger.ONE)
.multiply(popValue().getRangeValue().add(BigInteger.ONE));
}
/**
* Calculates number of conditional operators, including inline ternary operatior, for a token.
* @param ast inspected token.
* @return number of conditional operators.
* @see <a href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.23">
* Java Language Specification, §15.23</a>
* @see <a href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.24">
* Java Language Specification, §15.24</a>
* @see <a href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.25">
* Java Language Specification, §15.25</a>
*/
private static int countConditionalOperators(DetailAST ast) {
int number = 0;
for (DetailAST child = ast.getFirstChild(); child != null;
child = child.getNextSibling()) {
final int type = child.getType();
if (type == TokenTypes.LOR || type == TokenTypes.LAND) {
number++;
}
else if (type == TokenTypes.QUESTION) {
number += 2;
}
number += countConditionalOperators(child);
}
return number;
}
/**
* Finds a leaf, which is the most distant from the root.
* @param ast the root of tree.
* @return the leaf.
*/
private static DetailAST getLastToken(DetailAST ast) {
final DetailAST lastChild = ast.getLastChild();
final DetailAST result;
if (lastChild.getFirstChild() == null) {
result = lastChild;
}
else {
result = getLastToken(lastChild);
}
return result;
}
/**
* Counts number of case tokens subject to a case group token.
* @param ast case group token.
* @return number of case tokens.
*/
private static int countCaseTokens(DetailAST ast) {
int counter = 0;
for (DetailAST iterator = ast.getFirstChild(); iterator != null;
iterator = iterator.getNextSibling()) {
if (iterator.getType() == TokenTypes.LITERAL_CASE) {
counter++;
}
}
return counter;
}
/**
* Coordinates of token end. Used to prevent inline ternary
* operator from being processed twice.
*/
private static class TokenEnd {
/** End line of token. */
private int endLineNo;
/** End column of token. */
private int endColumnNo;
/**
* Sets end coordinates from given token.
* @param endToken token.
*/
public void setToken(DetailAST endToken) {
if (!isAfter(endToken)) {
endLineNo = endToken.getLineNo();
endColumnNo = endToken.getColumnNo();
}
}
/** Sets end token coordinates to the start of the file. */
public void reset() {
endLineNo = 0;
endColumnNo = 0;
}
/**
* Checks if saved coordinates located after given token.
* @param ast given token.
* @return true, if saved coordinates located after given token.
*/
public boolean isAfter(DetailAST ast) {
final int lineNo = ast.getLineNo();
final int columnNo = ast.getColumnNo();
boolean isAfter = true;
if (lineNo > endLineNo
|| lineNo == endLineNo
&& columnNo > endColumnNo) {
isAfter = false;
}
return isAfter;
}
}
/**
* Class that store range value and expression value.
*/
private static class Values {
/** NP value for range. */
private final BigInteger rangeValue;
/** NP value for expression. */
private final BigInteger expressionValue;
/**
* Constructor that assigns all of class fields.
* @param valueOfRange NP value for range
* @param valueOfExpression NP value for expression
*/
Values(BigInteger valueOfRange, BigInteger valueOfExpression) {
rangeValue = valueOfRange;
expressionValue = valueOfExpression;
}
/**
* Returns NP value for range.
* @return NP value for range
*/
public BigInteger getRangeValue() {
return rangeValue;
}
/**
* Returns NP value for expression.
* @return NP value for expression
*/
public BigInteger getExpressionValue() {
return expressionValue;
}
}
}