ParameterClassCheckVisitor.java

/*
 * Copyright 2003-2012 Dave Griffith, Bas Leijdekkers
 *
 * 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 com.siyeh.ig.bugs;

import com.intellij.psi.*;
import com.intellij.psi.util.PsiTreeUtil;
import com.siyeh.HardcodedMethodConstants;
import org.jetbrains.annotations.NotNull;

class ParameterClassCheckVisitor extends JavaRecursiveElementWalkingVisitor {

  private final PsiParameter parameter;

  private boolean checked;

  ParameterClassCheckVisitor(@NotNull PsiParameter parameter) {
    this.parameter = parameter;
  }

  @Override
  public void visitElement(@NotNull PsiElement element) {
    if (!checked) {
      super.visitElement(element);
    }
  }

  @Override
  public void visitMethodCallExpression(
    @NotNull PsiMethodCallExpression expression) {
    if (checked) {
      return;
    }
    super.visitMethodCallExpression(expression);
    if (isGetClassCall(expression) || isGetInstanceCall(expression) || isCallToSuperEquals(expression)) {
      checked = true;
    }
  }

  private boolean isGetInstanceCall(PsiMethodCallExpression methodCallExpression) {
    final PsiReferenceExpression methodExpression = methodCallExpression.getMethodExpression();
    final String methodName = methodExpression.getReferenceName();
    if (!HardcodedMethodConstants.IS_INSTANCE.equals(methodName)) {
      return false;
    }
    final PsiMethod method = methodCallExpression.resolveMethod();
    if (method == null) {
      return false;
    }
    final PsiClass aClass = method.getContainingClass();
    if (aClass == null) {
      return false;
    }
    final String className = aClass.getQualifiedName();
    if (!CommonClassNames.JAVA_LANG_CLASS.equals(className)) {
      return false;
    }
    final PsiExpressionList argumentList = methodCallExpression.getArgumentList();
    final PsiExpression[] expressions = argumentList.getExpressions();
    if (expressions.length != 1) {
      return false;
    }
    final PsiExpression expression = expressions[0];
    return isParameterReference(expression);
  }

  private boolean isGetClassCall(PsiMethodCallExpression methodCallExpression) {
    final PsiReferenceExpression methodExpression = methodCallExpression.getMethodExpression();
    final String methodName = methodExpression.getReferenceName();
    if (!HardcodedMethodConstants.GET_CLASS.equals(methodName)) {
      return false;
    }
    final PsiExpressionList argumentList = methodCallExpression.getArgumentList();
    final PsiExpression[] arguments = argumentList.getExpressions();
    if (arguments.length != 0) {
      return false;
    }
    final PsiMethod method = methodCallExpression.resolveMethod();
    if (method == null) {
      return false;
    }
    final PsiClass aClass = method.getContainingClass();
    if (aClass == null) {
      return false;
    }
    final String className = aClass.getQualifiedName();
    if (!CommonClassNames.JAVA_LANG_OBJECT.equals(className)) {
      return false;
    }
    final PsiExpression qualifier = methodExpression.getQualifierExpression();
    return isParameterReference(qualifier);
  }

  private boolean isCallToSuperEquals(PsiMethodCallExpression methodCallExpression) {
    final PsiReferenceExpression methodExpression = methodCallExpression.getMethodExpression();
    final PsiExpression qualifierExpression = methodExpression.getQualifierExpression();
    if (!(qualifierExpression instanceof PsiSuperExpression)) {
      return false;
    }
    final String name = methodExpression.getReferenceName();
    if (!HardcodedMethodConstants.EQUALS.equals(name)) {
      return false;
    }
    final PsiExpressionList argumentList = methodCallExpression.getArgumentList();
    final PsiExpression[] arguments = argumentList.getExpressions();
    if (arguments.length != 1) {
      return false;
    }
    final PsiExpression argument = arguments[0];
    if (!(argument instanceof PsiReferenceExpression)) {
      return false;
    }
    final PsiReferenceExpression referenceExpression = (PsiReferenceExpression)argument;
    final PsiElement target = referenceExpression.resolve();
    return parameter.equals(target);
  }

  @Override
  public void visitInstanceOfExpression(@NotNull PsiInstanceOfExpression expression) {
    if (checked) {
      return;
    }
    super.visitInstanceOfExpression(expression);
    final PsiExpression operand = expression.getOperand();
    if (isParameterReference(operand)) {
      checked = true;
    }
  }

  @Override
  public void visitTypeCastExpression(
    PsiTypeCastExpression expression) {
    if (checked) {
      return;
    }
    super.visitTypeCastExpression(expression);
    final PsiExpression operand = expression.getOperand();
    if (!isParameterReference(operand)) {
      return;
    }
    final PsiTryStatement statement = PsiTreeUtil.getParentOfType(expression, PsiTryStatement.class);
    if (statement == null) {
      return;
    }
    final PsiParameter[] parameters = statement.getCatchBlockParameters();
    if (parameters.length < 2) {
      return;
    }
    boolean nullPointerExceptionFound = false;
    boolean classCastExceptionFound = false;
    for (PsiParameter parameter : parameters) {
      final PsiType type = parameter.getType();
      if (type.equalsToText("java.lang.NullPointerException")) {
        nullPointerExceptionFound = true;
        if (classCastExceptionFound) {
          break;
        }
      }
      else if (type.equalsToText("java.lang.ClassCastException")) {
        classCastExceptionFound = true;
        if (nullPointerExceptionFound) {
          break;
        }
      }
    }
    if (classCastExceptionFound && nullPointerExceptionFound) {
      checked = true;
    }
  }

  private boolean isParameterReference(PsiExpression operand) {
    if (operand == null) {
      return false;
    }
    if (!(operand instanceof PsiReferenceExpression)) {
      return false;
    }
    final PsiReferenceExpression expression = (PsiReferenceExpression)operand;
    final PsiElement referent = expression.resolve();
    return referent != null && referent.equals(parameter);
  }

  public boolean isChecked() {
    return checked;
  }
}