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/*******************************************************************************
* Copyright (c) 2010, 2013 Gil Barash
* 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:
* Gil Barash - Initial implementation
* Elena laskavaia - Rewrote checker to reduce false positives in complex cases
* Sergey Prigogin (Google)
*******************************************************************************/
package org.eclipse.cdt.codan.internal.checkers;
import org.eclipse.cdt.codan.core.cxx.CxxAstUtils;
import org.eclipse.cdt.codan.core.cxx.model.AbstractIndexAstChecker;
import org.eclipse.cdt.codan.core.model.ICheckerWithPreferences;
import org.eclipse.cdt.codan.core.model.IProblemLocation;
import org.eclipse.cdt.codan.core.model.IProblemLocationFactory;
import org.eclipse.cdt.codan.core.model.IProblemWorkingCopy;
import org.eclipse.cdt.core.dom.ast.ASTVisitor;
import org.eclipse.cdt.core.dom.ast.IASTBreakStatement;
import org.eclipse.cdt.core.dom.ast.IASTCaseStatement;
import org.eclipse.cdt.core.dom.ast.IASTComment;
import org.eclipse.cdt.core.dom.ast.IASTCompoundStatement;
import org.eclipse.cdt.core.dom.ast.IASTContinueStatement;
import org.eclipse.cdt.core.dom.ast.IASTDefaultStatement;
import org.eclipse.cdt.core.dom.ast.IASTExpressionStatement;
import org.eclipse.cdt.core.dom.ast.IASTFileLocation;
import org.eclipse.cdt.core.dom.ast.IASTGotoStatement;
import org.eclipse.cdt.core.dom.ast.IASTIfStatement;
import org.eclipse.cdt.core.dom.ast.IASTMacroExpansionLocation;
import org.eclipse.cdt.core.dom.ast.IASTNode;
import org.eclipse.cdt.core.dom.ast.IASTNodeLocation;
import org.eclipse.cdt.core.dom.ast.IASTNullStatement;
import org.eclipse.cdt.core.dom.ast.IASTReturnStatement;
import org.eclipse.cdt.core.dom.ast.IASTStatement;
import org.eclipse.cdt.core.dom.ast.IASTSwitchStatement;
import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit;
public class CaseBreakChecker extends AbstractIndexAstChecker implements ICheckerWithPreferences {
public static final String ER_ID = "org.eclipse.cdt.codan.internal.checkers.CaseBreakProblem"; //$NON-NLS-1$
public static final String PARAM_LAST_CASE = "last_case_param"; //$NON-NLS-1$
public static final String PARAM_EMPTY_CASE = "empty_case_param"; //$NON-NLS-1$
public static final String PARAM_NO_BREAK_COMMENT = "no_break_comment"; //$NON-NLS-1$
public static final String DEFAULT_NO_BREAK_COMMENT = "no break"; //$NON-NLS-1$
private boolean fCheckLastCase; // Should we check the last case in the switch?
private boolean fCheckEmptyCase; // Should we check an empty case (a case without any statements within it)
private String fNoBreakComment; // The comment suppressing this warning
/**
* This visitor looks for "switch" statements and invokes "SwitchVisitor" on them.
*/
class SwitchFindingVisitor extends ASTVisitor {
SwitchFindingVisitor() {
shouldVisitStatements = true;
}
/**
* @param statement
* @return true iff the statement is on of:
* - "break" (checks that the break actually exists the
* "switch")
* - "return"
* - "continue"
* - "goto" (does not check that the goto actually exists the
* switch)
* - "throw"
* - "exit"
*/
protected boolean isBreakOrExitStatement(IASTStatement statement) {
return (statement instanceof IASTBreakStatement) || statement instanceof IASTReturnStatement
|| statement instanceof IASTContinueStatement || statement instanceof IASTGotoStatement
|| CxxAstUtils.isThrowStatement(statement) || CxxAstUtils.isExitStatement(statement);
}
@Override
public int visit(IASTStatement statement) {
if (statement instanceof IASTSwitchStatement && !isProducedByMacroExpansion(statement)) {
IASTSwitchStatement switchStmt = (IASTSwitchStatement) statement;
IASTStatement body = switchStmt.getBody();
if (body instanceof IASTCompoundStatement) {
// If not it is not really a switch
IASTStatement[] statements = ((IASTCompoundStatement) body).getStatements();
IASTStatement prevCase = null;
for (int i = 0; i < statements.length; i++) {
IASTStatement curr = statements[i];
if (curr instanceof IASTSwitchStatement) {
visit(curr);
}
IASTStatement next = null;
if (i < statements.length - 1)
next = statements[i + 1];
IASTStatement prev = null;
if (i > 0)
prev = statements[i - 1];
if (isCaseStatement(curr)) {
prevCase = curr;
}
// Next is case or end of switch - means this one is the last
if (prevCase != null && (isCaseStatement(next) || next == null)) {
// Check that current statement end with break or any other exit statement
if (!fCheckEmptyCase && isCaseStatement(curr) && next != null) {
continue; // Empty case and we don't care
}
if (!fCheckLastCase && next == null) {
continue; // Last case and we don't care
}
// If this is the null statement, base the decision on the previous statement
// instead (if there is one). Null statements can sneak in via macros in cases
// where the macro expansion ends in a semicolon, and the macro use is followed
// by a semicolon as well.
if (curr instanceof IASTNullStatement && (prev != prevCase)) {
curr = prev;
}
if (!isProducedByMacroExpansion(prevCase) && isFallThroughStamement(curr)) {
IASTComment comment = null;
if (next != null) {
comment = getLeadingComment(next);
} else {
comment = getFreestandingComment(statement);
if (comment == null)
comment = getFreestandingComment(body);
}
if (comment != null) {
String str = getTrimmedComment(comment);
if (str.toLowerCase().contains(fNoBreakComment.toLowerCase()))
continue;
}
reportProblem(curr);
}
}
}
}
return PROCESS_SKIP;
}
return PROCESS_CONTINUE;
}
/**
* @param statement
* @return
*/
public boolean isCaseStatement(IASTStatement statement) {
return statement instanceof IASTCaseStatement || statement instanceof IASTDefaultStatement;
}
/**
* @param body
* @return
*/
public boolean isFallThroughStamement(IASTStatement body) {
if (body == null)
return true;
if (body instanceof IASTCompoundStatement) {
IASTStatement[] statements = ((IASTCompoundStatement) body).getStatements();
if (statements.length > 0) {
return isFallThroughStamement(statements[statements.length - 1]);
}
return true;
} else if (isBreakOrExitStatement(body)) {
return false;
} else if (body instanceof IASTExpressionStatement) {
return true;
} else if (body instanceof IASTIfStatement) {
IASTIfStatement ifs = (IASTIfStatement) body;
return isFallThroughStamement(ifs.getThenClause()) || isFallThroughStamement(ifs.getElseClause());
}
return true; // TODO
}
}
private void reportProblem(IASTStatement curr) {
reportProblem(ER_ID, getProblemLocationAtEndOfNode(curr));
}
private IProblemLocation getProblemLocationAtEndOfNode(IASTNode astNode) {
IASTFileLocation astLocation = astNode.getFileLocation();
int line = astLocation.getEndingLineNumber();
IProblemLocationFactory locFactory = getRuntime().getProblemLocationFactory();
return locFactory.createProblemLocation(getFile(), -1, -1, line);
}
/**
* Checks if the given statement is a result of macro expansion with a possible
* exception for the trailing semicolon.
*
* @param statement the statement to check.
* @return <code>true</code> if the statement is a result of macro expansion
*/
private boolean isProducedByMacroExpansion(IASTStatement statement) {
IASTNodeLocation[] locations = statement.getNodeLocations();
return locations.length > 0 && locations[0] instanceof IASTMacroExpansionLocation
&& (locations.length == 1 || locations.length == 2 && locations[1].getNodeLength() == 1);
}
/**
* @param comment
* @return
*/
public String getTrimmedComment(IASTComment comment) {
String str = new String(comment.getComment());
if (comment.isBlockComment())
str = str.substring(2, str.length() - 2);
else
str = str.substring(2);
str = str.trim();
return str;
}
/**
* @param statement
* @return
*/
public IASTComment getLeadingComment(IASTStatement statement) {
return getCommentMap().getLastLeadingCommentForNode(statement);
}
/**
* @param statement
* @return
*/
public IASTComment getFreestandingComment(IASTStatement statement) {
return getCommentMap().getLastFreestandingCommentForNode(statement);
}
@Override
public void initPreferences(IProblemWorkingCopy problem) {
super.initPreferences(problem);
addPreference(problem, PARAM_NO_BREAK_COMMENT, CheckersMessages.CaseBreakChecker_DefaultNoBreakCommentDescription,
DEFAULT_NO_BREAK_COMMENT);
addPreference(problem, PARAM_LAST_CASE, CheckersMessages.CaseBreakChecker_LastCaseDescription, Boolean.FALSE);
addPreference(problem, PARAM_EMPTY_CASE, CheckersMessages.CaseBreakChecker_EmptyCaseDescription, Boolean.FALSE);
}
@Override
public void processAst(IASTTranslationUnit ast) {
fCheckLastCase = (Boolean) getPreference(getProblemById(ER_ID, getFile()), PARAM_LAST_CASE);
fCheckEmptyCase = (Boolean) getPreference(getProblemById(ER_ID, getFile()), PARAM_EMPTY_CASE);
fNoBreakComment = (String) getPreference(getProblemById(ER_ID, getFile()), PARAM_NO_BREAK_COMMENT);
SwitchFindingVisitor visitor = new SwitchFindingVisitor();
ast.accept(visitor);
}
}
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