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Checkstyle is a development tool to help programmers write Java code that adheres to a coding standard
////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2015 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.coding;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.regex.Pattern;
import com.puppycrawl.tools.checkstyle.api.Check;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.CommonUtils;
/**
*
* Restricts the number of return statements in methods, constructors and lambda expressions
* (2 by default). Ignores specified methods ({@code equals()} by default).
*
*
* Rationale: Too many return points can be indication that code is
* attempting to do too much or may be difficult to understand.
*
*
* @author Simon Harris
*/
public final class ReturnCountCheck extends Check {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY = "return.count";
/** Stack of method contexts. */
private final Deque contextStack = new ArrayDeque<>();
/** The format string of the regexp. */
private String format = "^equals$";
/** The regexp to match against. */
private Pattern regexp = Pattern.compile(format);
/** Maximum allowed number of return statements. */
private int max = 2;
/** Current method context. */
private Context context;
@Override
public int[] getDefaultTokens() {
return new int[] {
TokenTypes.CTOR_DEF,
TokenTypes.METHOD_DEF,
TokenTypes.LAMBDA,
TokenTypes.LITERAL_RETURN,
};
}
@Override
public int[] getRequiredTokens() {
return new int[] {TokenTypes.LITERAL_RETURN};
}
@Override
public int[] getAcceptableTokens() {
return new int[] {
TokenTypes.CTOR_DEF,
TokenTypes.METHOD_DEF,
TokenTypes.LAMBDA,
TokenTypes.LITERAL_RETURN,
};
}
/**
* Set the format to the specified regular expression.
* @param format a {@code String} value
* @throws org.apache.commons.beanutils.ConversionException unable to parse format
*/
public void setFormat(String format) {
this.format = format;
regexp = CommonUtils.createPattern(format);
}
/**
* Getter for max property.
* @return maximum allowed number of return statements.
*/
public int getMax() {
return max;
}
/**
* Setter for max property.
* @param max maximum allowed number of return statements.
*/
public void setMax(int max) {
this.max = max;
}
@Override
public void beginTree(DetailAST rootAST) {
context = new Context(false);
contextStack.clear();
}
@Override
public void visitToken(DetailAST ast) {
switch (ast.getType()) {
case TokenTypes.CTOR_DEF:
case TokenTypes.METHOD_DEF:
visitMethodDef(ast);
break;
case TokenTypes.LAMBDA:
visitLambda();
break;
case TokenTypes.LITERAL_RETURN:
context.visitLiteralReturn();
break;
default:
throw new IllegalStateException(ast.toString());
}
}
@Override
public void leaveToken(DetailAST ast) {
switch (ast.getType()) {
case TokenTypes.CTOR_DEF:
case TokenTypes.METHOD_DEF:
case TokenTypes.LAMBDA:
leave(ast);
break;
case TokenTypes.LITERAL_RETURN:
// Do nothing
break;
default:
throw new IllegalStateException(ast.toString());
}
}
/**
* Creates new method context and places old one on the stack.
* @param ast method definition for check.
*/
private void visitMethodDef(DetailAST ast) {
contextStack.push(context);
final DetailAST methodNameAST = ast.findFirstToken(TokenTypes.IDENT);
final boolean check = !regexp.matcher(methodNameAST.getText()).find();
context = new Context(check);
}
/**
* Checks number of return statements and restore previous context.
* @param ast node to leave.
*/
private void leave(DetailAST ast) {
context.checkCount(ast);
context = contextStack.pop();
}
/**
* Creates new lambda context and places old one on the stack.
*/
private void visitLambda() {
contextStack.push(context);
context = new Context(true);
}
/**
* Class to encapsulate information about one method.
* @author Simon Harris
*/
private class Context {
/** Whether we should check this method or not. */
private final boolean checking;
/** Counter for return statements. */
private int count;
/**
* Creates new method context.
* @param checking should we check this method or not.
*/
Context(boolean checking) {
this.checking = checking;
count = 0;
}
/** Increase number of return statements. */
public void visitLiteralReturn() {
++count;
}
/**
* Checks if number of return statements in method more
* than allowed.
* @param ast method def associated with this context.
*/
public void checkCount(DetailAST ast) {
if (checking && count > getMax()) {
log(ast.getLineNo(), ast.getColumnNo(), MSG_KEY,
count, getMax());
}
}
}
}