content: /*
   * Copyright 2016 HuntBugs contributors
   * 
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   * 
   *     http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package one.util.huntbugs.detect;
  
  import com.strobel.decompiler.ast.AstCode;
  import com.strobel.decompiler.ast.Expression;
  
  import one.util.huntbugs.registry.MethodContext;
  import one.util.huntbugs.registry.anno.AstNodes;
  import one.util.huntbugs.registry.anno.AstVisitor;
  import one.util.huntbugs.registry.anno.WarningDefinition;
  import one.util.huntbugs.util.Exprs;
  import one.util.huntbugs.util.Nodes;
  
  /**
   * @author Tagir Valeev
   *
   */
  @WarningDefinition(category = "BadPractice", name = "AverageComputationCouldOverflow", maxScore = 35)
  public class AverageComputation {
      @AstVisitor(nodes = AstNodes.EXPRESSIONS)
      public void visitExpression(Expression expr, MethodContext mc) {
          if (expr.getCode() != AstCode.LoadElement && expr.getCode() != AstCode.StoreElement)
              return;
          Expression idx = Exprs.getChild(expr, 1);
          if (!isDiv2(idx))
              return;
          Expression orig = Exprs.getChild(idx, 0);
          if (orig.getCode() != AstCode.Add)
              return;
          mc.report("AverageComputationCouldOverflow", 0, idx);
      }
  
      private boolean isDiv2(Expression idx) {
          return (idx.getCode() == AstCode.Div && Integer.valueOf(2).equals(Nodes.getConstant(idx.getArguments().get(1))))
              || (idx.getCode() == AstCode.Shr && Integer.valueOf(1).equals(Nodes.getConstant(idx.getArguments().get(1))));
      }
  }
  