1 files changed, 196 insertions, 0 deletions
diff --git a/org.eclipse.cdt.codan.checkers/src/org/eclipse/cdt/codan/internal/checkers/StatementHasNoEffectChecker.java b/org.eclipse.cdt.codan.checkers/src/org/eclipse/cdt/codan/internal/checkers/StatementHasNoEffectChecker.java
new file mode 100644
index 0000000..331e86b
--- /dev/null
+++ b/org.eclipse.cdt.codan.checkers/src/org/eclipse/cdt/codan/internal/checkers/StatementHasNoEffectChecker.java
@@ -0,0 +1,196 @@
+/*******************************************************************************
+ * Copyright (c) 2009, 2010 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.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.IProblemWorkingCopy;
+import org.eclipse.cdt.core.dom.ast.ASTVisitor;
+import org.eclipse.cdt.core.dom.ast.IASTBinaryExpression;
+import org.eclipse.cdt.core.dom.ast.IASTCompoundStatement;
+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.IASTNode;
+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.core.dom.ast.gnu.IGNUASTCompoundStatementExpression;
+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 {
+	public static final String ER_ID = "org.eclipse.cdt.codan.internal.checkers.StatementHasNoEffectProblem"; //$NON-NLS-1$
+	public static final String PARAM_MACRO_ID = "macro"; //$NON-NLS-1$
+	public static final String PARAM_EXCEPT_ARG_LIST = "exceptions"; //$NON-NLS-1$
+
+	public void processAst(IASTTranslationUnit ast) {
+		ast.accept(new CheckStmpVisitor());
+	}
+
+	class CheckStmpVisitor extends ASTVisitor {
+		CheckStmpVisitor() {
+			shouldVisitStatements = true;
+		}
+
+		public int visit(IASTStatement stmt) {
+			if (stmt instanceof IASTExpressionStatement) {
+				IASTExpression expression = ((IASTExpressionStatement) stmt)
+						.getExpression();
+				if (hasNoEffect(expression)) {
+					boolean inMacro = CxxAstUtils.getInstance().isInMacro(
+							expression);
+					boolean shouldReportInMacro = shouldReportInMacro();
+					if (inMacro && !shouldReportInMacro)
+						return PROCESS_SKIP;
+					String arg = expression.getRawSignature();
+					if (!isFilteredArg(arg))
+						reportProblem(ER_ID, stmt, arg);
+				}
+				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 (isPossibleAssignment(binExpr))
+					return false;
+				switch (binExpr.getOperator()) {
+					case IASTBinaryExpression.op_logicalOr:
+					case IASTBinaryExpression.op_logicalAnd:
+						return hasNoEffect(binExpr.getOperand1())
+								&& hasNoEffect(binExpr.getOperand2());
+				}
+				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:
+					case IASTUnaryExpression.op_throw:
+						return false;
+					case IASTUnaryExpression.op_bracketedPrimary:
+						return hasNoEffect(unaryExpr.getOperand());
+				}
+				return true;
+			}
+			// simply a;
+			if (e instanceof IASTIdExpression) {
+				// check if it is part of GNU comp stmt expression i.e. ({foo();a;})
+				IASTNode parent = e.getParent();
+				if (parent instanceof IASTExpressionStatement) {
+					IASTNode parent2 = parent.getParent();
+					if (parent2 instanceof IASTCompoundStatement) {
+						IASTNode parent3 = parent2.getParent();
+						if (parent3 instanceof IGNUASTCompoundStatementExpression) {
+							return false;
+						}
+					}
+				}
+				return true;
+			}
+			return false;
+		}
+	}
+
+	public void initPreferences(IProblemWorkingCopy problem) {
+		super.initPreferences(problem);
+		addPreference(problem, PARAM_MACRO_ID,
+				CheckersMessages.StatementHasNoEffectChecker_ParameterMacro,
+				Boolean.TRUE);
+		addListPreference(
+				problem,
+				PARAM_EXCEPT_ARG_LIST,
+				CheckersMessages.GenericParameter_ParameterExceptions,
+				CheckersMessages.GenericParameter_ParameterExceptionsItem);
+	}
+
+	/**s
+	 * @param paramExceptArgList
+	 * @param arg
+	 * @return
+	 */
+	public boolean isFilteredArg(String arg) {
+		Object[] arr = (Object[]) getPreference(
+				getProblemById(ER_ID, getFile()), PARAM_EXCEPT_ARG_LIST);
+		for (int i = 0; i < arr.length; i++) {
+			String str = (String) arr[i];
+			if (arg.equals(str))
+				return true;
+		}
+		return false;
+	}
+
+	/**
+	 * @return
+	 */
+	public boolean shouldReportInMacro() {
+		return (Boolean) getPreference(getProblemById(ER_ID, getFile()),
+				PARAM_MACRO_ID);
+	}
+
+	@SuppressWarnings("restriction")
+	public boolean isPossibleAssignment(IASTBinaryExpression expr) {
+		switch (expr.getOperator()) {
+			case IASTBinaryExpression.op_assign:
+			case IASTBinaryExpression.op_binaryAndAssign:
+			case IASTBinaryExpression.op_binaryOrAssign:
+			case IASTBinaryExpression.op_binaryXorAssign:
+			case IASTBinaryExpression.op_divideAssign:
+			case IASTBinaryExpression.op_minusAssign:
+			case IASTBinaryExpression.op_moduloAssign:
+			case IASTBinaryExpression.op_multiplyAssign:
+			case IASTBinaryExpression.op_plusAssign:
+			case IASTBinaryExpression.op_shiftLeftAssign:
+			case IASTBinaryExpression.op_shiftRightAssign:
+				return true;
+		}
+		if (expr instanceof CPPASTBinaryExpression) {
+			// unfortunately ICPPASTBinaryExpression does not have
+			// getOverload public method
+			CPPASTBinaryExpression cppBin = (CPPASTBinaryExpression) expr;
+			ICPPFunction overload = cppBin.getOverload();
+			if (overload != null)
+				return true;
+			IType expressionType = cppBin.getOperand1().getExpressionType();
+			if (!(expressionType instanceof IBasicType)) {
+				return true; // must be overloaded but parser could not
+				// find it
+			}
+		}
+		return false;
+	}
+}