/*
* SonarQube Java
* Copyright (C) 2012-2016 SonarSource SA
* mailto:contact AT sonarsource DOT com
*
* This program 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 3 of the License, or (at your option) any later version.
*
* This program 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 program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.sonar.java.checks;
import com.google.common.collect.ImmutableList;
import org.sonar.check.Rule;
import org.sonar.java.matcher.MethodMatcher;
import org.sonar.java.matcher.MethodMatcherCollection;
import org.sonar.java.model.ExpressionUtils;
import org.sonar.java.model.LiteralUtils;
import org.sonar.java.resolve.JavaType;
import org.sonar.plugins.java.api.IssuableSubscriptionVisitor;
import org.sonar.plugins.java.api.semantic.Type;
import org.sonar.plugins.java.api.tree.BinaryExpressionTree;
import org.sonar.plugins.java.api.tree.ExpressionTree;
import org.sonar.plugins.java.api.tree.LiteralTree;
import org.sonar.plugins.java.api.tree.MethodInvocationTree;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.plugins.java.api.tree.TypeCastTree;
import javax.annotation.CheckForNull;
import java.util.List;
@Rule(key = "S2185")
public class ConstantMathCheck extends IssuableSubscriptionVisitor {
private static final String ABS = "abs";
private static final String CEIL = "ceil";
private static final String DOUBLE = "double";
private static final String FLOAT = "float";
private static final String FLOOR = "floor";
private static final String MATH_PACKAGE_NAME = "java.lang.Math";
private static final String ROUND = "round";
private static final MethodMatcherCollection CONSTANT_WITH_LITERAL_METHODS = MethodMatcherCollection.create(
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name(ABS).addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name(ABS).addParameter(FLOAT),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name(ABS).addParameter("int"),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name(ABS).addParameter("long")
);
private static final MethodMatcherCollection TRUNCATION_METHODS = MethodMatcherCollection.create(
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name(CEIL).addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name(CEIL).addParameter(FLOAT),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name(FLOOR).addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name(FLOOR).addParameter(FLOAT),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("rint").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name(ROUND).addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name(ROUND).addParameter(FLOAT)
);
private static final MethodMatcherCollection CONSTANT_WITH_ZERO_METHODS = MethodMatcherCollection.create(
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("atan2").addParameter(DOUBLE).addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("cos").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("cosh").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("expm1").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("sin").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("sinh").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("tan").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("tanh").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("toRadians").addParameter(DOUBLE)
);
private static final MethodMatcherCollection CONSTANT_WITH_ZERO_OR_ONE_METHODS = MethodMatcherCollection.create(
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("acos").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("asin").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("atan").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("cbrt").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("exp").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("log").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("log10").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("sqrt").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("toDegrees").addParameter(DOUBLE),
MethodMatcher.create().typeDefinition(MATH_PACKAGE_NAME).name("exp").addParameter(DOUBLE)
);
@Override
public List<Tree.Kind> nodesToVisit() {
return ImmutableList.of(Tree.Kind.REMAINDER, Tree.Kind.METHOD_INVOCATION);
}
@Override
public void visitNode(Tree tree) {
if (hasSemantic()) {
if (tree.is(Tree.Kind.REMAINDER)) {
BinaryExpressionTree remainderTree = (BinaryExpressionTree) tree;
if (isIntegralOne(remainderTree.rightOperand()) && isIntOrLong(remainderTree.leftOperand())) {
reportIssue(remainderTree.operatorToken(), "Remove this computation of % 1, which always evaluates to zero.");
}
} else {
MethodInvocationTree mit = (MethodInvocationTree) tree;
if (isConstantWithLiteral(mit) || isTruncation(mit) || isConstantWithZero(mit) || isConstantWithZeroOrOne(mit)) {
reportIssue(mit.methodSelect(), String.format("Remove this silly call to \"Math.%s\"", mit.symbol().name()));
}
}
}
}
private static boolean isIntOrLong(ExpressionTree expression) {
JavaType type = (JavaType) expression.symbolType();
return isIntegral(type) || (type.isPrimitiveWrapper() && isIntegral(type.primitiveType()));
}
private static boolean isTruncation(MethodInvocationTree methodTree) {
return TRUNCATION_METHODS.anyMatch(methodTree) && isCastFromIntegralToFloating(ExpressionUtils.skipParentheses(methodTree.arguments().get(0)));
}
private static boolean isConstantWithLiteral(MethodInvocationTree methodTree) {
return CONSTANT_WITH_LITERAL_METHODS.anyMatch(methodTree) && isConstant(methodTree.arguments().get(0));
}
private static boolean isConstantWithZero(MethodInvocationTree methodTree) {
return CONSTANT_WITH_ZERO_METHODS.anyMatch(methodTree) && isFloatingZero(methodTree.arguments().get(0));
}
private static boolean isConstantWithZeroOrOne(MethodInvocationTree methodTree) {
return CONSTANT_WITH_ZERO_OR_ONE_METHODS.anyMatch(methodTree) && isFloatingZeroOrOne(methodTree.arguments().get(0));
}
private static boolean isCastFromIntegralToFloating(ExpressionTree tree) {
Type resultType = tree.symbolType();
// explicit cast
if (tree.is(Tree.Kind.TYPE_CAST) && isIntegral(getInnerType(((TypeCastTree) tree).expression())) && (resultType.is(DOUBLE) || resultType.is(FLOAT))) {
return true;
}
// implicit cast
return isIntegral(resultType);
}
private static boolean isConstant(ExpressionTree tree) {
return getInnerExpression(tree).is(Tree.Kind.CHAR_LITERAL, Tree.Kind.DOUBLE_LITERAL, Tree.Kind.FLOAT_LITERAL, Tree.Kind.INT_LITERAL, Tree.Kind.LONG_LITERAL);
}
private static boolean isIntegral(Type type) {
return type.isPrimitive() && !type.is(DOUBLE) && !type.is(FLOAT);
}
private static boolean isIntegralOne(ExpressionTree tree) {
Long value = LiteralUtils.longLiteralValue(tree);
return value != null && value == 1;
}
private static ExpressionTree getInnerExpression(ExpressionTree tree) {
ExpressionTree result = ExpressionUtils.skipParentheses(tree);
while (result.is(Tree.Kind.TYPE_CAST)) {
result = ExpressionUtils.skipParentheses(((TypeCastTree) result).expression());
}
return result;
}
private static Type getInnerType(ExpressionTree tree) {
return getInnerExpression(tree).symbolType();
}
private static boolean isFloatingZero(ExpressionTree tree) {
Integer value = getFloatingZeroOrOne(tree);
return value != null && value == 0;
}
private static boolean isFloatingZeroOrOne(ExpressionTree tree) {
return getFloatingZeroOrOne(tree) != null;
}
@CheckForNull
private static Integer getFloatingZeroOrOne(ExpressionTree tree) {
ExpressionTree expressionTree = ExpressionUtils.skipParentheses(tree);
if (expressionTree.is(Tree.Kind.DOUBLE_LITERAL, Tree.Kind.FLOAT_LITERAL)) {
String value = ((LiteralTree) expressionTree).value();
if ("0.0".equals(value) || "0.0d".equalsIgnoreCase(value) || "0.0f".equalsIgnoreCase(value)) {
return 0;
} else if ("1.0".equals(value) || "1.0d".equalsIgnoreCase(value) || "1.0f".equalsIgnoreCase(value)) {
return 1;
}
}
return null;
}
}