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 java.util.List;
  
  import com.strobel.assembler.metadata.MethodDefinition;
  import com.strobel.assembler.metadata.MethodReference;
  import com.strobel.assembler.metadata.ParameterDefinition;
  import com.strobel.decompiler.ast.AstCode;
  import com.strobel.decompiler.ast.Condition;
  import com.strobel.decompiler.ast.Expression;
  import com.strobel.decompiler.ast.Lambda;
  import com.strobel.decompiler.ast.Loop;
  import com.strobel.decompiler.ast.Node;
  import com.strobel.decompiler.ast.Switch;
  import com.strobel.decompiler.ast.TryCatchBlock;
  
  import one.util.huntbugs.flow.ValuesFlow;
  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.MethodVisitor;
  import one.util.huntbugs.registry.anno.WarningDefinition;
  import one.util.huntbugs.util.Exprs;
  import one.util.huntbugs.util.NodeChain;
  import one.util.huntbugs.util.Nodes;
  
  /**
   * @author Tagir Valeev
   *
   */
  @WarningDefinition(category = "Correctness", name = "InfiniteRecursion", maxScore = 90)
  public class InfiniteRecursion {
      boolean stateChange;
      boolean controlTransfer;
  
      @MethodVisitor
      public void init() {
          stateChange = controlTransfer = false;
      }
  
      @AstVisitor(nodes = AstNodes.EXPRESSIONS)
      public boolean visit(Expression expr, NodeChain nc, MethodContext mc, MethodDefinition md) {
          if (selfCall(expr, md) && (!stateChange && checkArgs(expr) || !controlTransfer && checkControlFlow(nc))) {
              mc.report("InfiniteRecursion", 0, expr);
          }
          if (expr.getCode() == AstCode.StoreElement || expr.getCode() == AstCode.PutField
              || expr.getCode() == AstCode.PutStatic) {
              stateChange = true;
          }
          if ((Nodes.isInvoke(expr) || expr.getCode() == AstCode.InitObject) && !Nodes.isSideEffectFree(expr)) {
              stateChange = true;
          }
          if (expr.getCode() == AstCode.Return || expr.getCode() == AstCode.AThrow
              || expr.getCode() == AstCode.LoopContinue || expr.getCode() == AstCode.LoopOrSwitchBreak
              || expr.getCode() == AstCode.Goto) {
              controlTransfer = true;
          }
          if (controlTransfer && stateChange)
              return false;
          return true;
      }
  
      private boolean selfCall(Expression expr, MethodDefinition md) {
          if (!(expr.getOperand() instanceof MethodReference))
              return false;
          MethodReference mr = (MethodReference) expr.getOperand();
          if (!mr.isEquivalentTo(md))
              return false;
          switch (expr.getCode()) {
          case InvokeStatic:
              return md.isStatic();
          case InitObject:
          case InvokeSpecial:
              return md.isConstructor();
          case InvokeVirtual:
          case InvokeInterface:
              return !md.isStatic() && Exprs.isThis(expr.getArguments().get(0));
          default:
              return false;
          }
      }
  
      private boolean checkControlFlow(NodeChain nc) {
          while (nc != null) {
              Node node = nc.getNode();
              if (node instanceof Condition || node instanceof Switch || node instanceof Loop
                  || node instanceof TryCatchBlock || node instanceof Lambda)
                  return false;
              if (node instanceof Expression) {
                  Expression expr = (Expression)node;
                  if(expr.getCode() == AstCode.LogicalAnd || expr.getCode() == AstCode.LogicalOr || expr.getCode() == AstCode.TernaryOp)
                      return false;
              }
              nc = nc.getParent();
          }
          return true;
      }
  
      private boolean checkArgs(Expression expr) {
          List<Expression> args = expr.getArguments();
          if ((expr.getCode() == AstCode.InvokeInterface || expr.getCode() == AstCode.InvokeVirtual)
              && !Exprs.isThis(expr.getArguments().get(0)))
              return false;
          int base = (expr.getCode() == AstCode.InvokeStatic || expr.getCode() == AstCode.InitObject) ? 0 : 1;
          for (int i = base; i < args.size(); i++) {
              Expression arg = args.get(i);
              Object operand = ValuesFlow.getSource(arg).getOperand();
              if (!(operand instanceof ParameterDefinition))
                  return false;
              ParameterDefinition pd = (ParameterDefinition) operand;
              if (pd.getPosition() != i - base)
                  return false;
          }
          return true;
      }
  }
  