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/*******************************************************************************
* Copyright (c) 2009 Alena Laskavaia
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Alena Laskavaia - initial API and implementation
*******************************************************************************/
package org.eclipse.cdt.codan.checkers.sample;
import org.eclipse.cdt.codan.core.model.AbstractIndexAstChecker;
import org.eclipse.cdt.core.dom.ast.ASTVisitor;
import org.eclipse.cdt.core.dom.ast.IASTBinaryExpression;
import org.eclipse.cdt.core.dom.ast.IASTExpression;
import org.eclipse.cdt.core.dom.ast.IASTExpressionStatement;
import org.eclipse.cdt.core.dom.ast.IASTIdExpression;
import org.eclipse.cdt.core.dom.ast.IASTStatement;
import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit;
import org.eclipse.cdt.core.dom.ast.IASTUnaryExpression;
import org.eclipse.cdt.core.dom.ast.IBasicType;
import org.eclipse.cdt.core.dom.ast.IType;
import org.eclipse.cdt.core.dom.ast.cpp.ICPPFunction;
import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPASTBinaryExpression;
/**
* Checker that detects statements without effect such as
*
* a+b;
*
* or
*
* +b;
*
*
*/
public class StatementHasNoEffectChecker extends AbstractIndexAstChecker {
private static final String ER_ID = "org.eclipse.cdt.codan.checkers.sample.StatementHasNoEffectProblem";
public void processAst(IASTTranslationUnit ast) {
// traverse the ast using the visitor pattern.
ast.accept(new CheckStmpVisitor());
}
class CheckStmpVisitor extends ASTVisitor {
CheckStmpVisitor() {
shouldVisitStatements = true;
}
public int visit(IASTStatement stmt) {
if (stmt instanceof IASTExpressionStatement) {
if (hasNoEffect(((IASTExpressionStatement) stmt)
.getExpression())) {
reportProblem(ER_ID, stmt, "Statement has no effect");
}
return PROCESS_SKIP;
}
return PROCESS_CONTINUE;
}
/**
* We consider has not effect binary statements without assignment and
* unary statement which is not dec and inc. If operator is overloaded
* we not going to bother.
*
* @param e
* @return
*/
private boolean hasNoEffect(IASTExpression e) {
if (e instanceof IASTBinaryExpression) {
IASTBinaryExpression binExpr = (IASTBinaryExpression) e;
if (binExpr.getOperator() == IASTBinaryExpression.op_assign)
return false;
if (binExpr instanceof CPPASTBinaryExpression) {
// unfortunately ICPPASTBinaryExpression does not have
// getOverload public method
CPPASTBinaryExpression cppBin = (CPPASTBinaryExpression) binExpr;
ICPPFunction overload = cppBin.getOverload();
if (overload != null)
return false;
IType expressionType = binExpr.getOperand1()
.getExpressionType();
if (!(expressionType instanceof IBasicType)) {
return false; // must be overloaded but parser could not
// find it
}
}
return true;
}
if (e instanceof IASTUnaryExpression) {
IASTUnaryExpression unaryExpr = (IASTUnaryExpression) e;
int operator = unaryExpr.getOperator();
switch (operator) {
case IASTUnaryExpression.op_postFixDecr:
case IASTUnaryExpression.op_prefixDecr:
case IASTUnaryExpression.op_postFixIncr:
case IASTUnaryExpression.op_prefixIncr:
return false;
}
return true;
}
if (e instanceof IASTIdExpression) {
// simply a;
return true;
}
return false;
}
}
}
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