plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bugs/NullArgumentToVariableArgMethodInspection.java

/*
 * Copyright 2003-2007 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.PsiUtil;
import com.siyeh.InspectionGadgetsBundle;
import com.siyeh.ig.BaseInspection;
import com.siyeh.ig.BaseInspectionVisitor;
import com.siyeh.ig.psiutils.ExpressionUtils;
import org.jetbrains.annotations.NotNull;

public class NullArgumentToVariableArgMethodInspection
  extends BaseInspection {

  @Override
  @NotNull
  public String getDisplayName() {
    return InspectionGadgetsBundle.message(
      "null.argument.to.var.arg.method.display.name");
  }

  @Override
  @NotNull
  public String buildErrorString(Object... infos) {
    return InspectionGadgetsBundle.message(
      "null.argument.to.var.arg.method.problem.descriptor");
  }

  @Override
  public boolean isEnabledByDefault() {
    return true;
  }

  @Override
  public BaseInspectionVisitor buildVisitor() {
    return new NullArgumentToVariableArgVisitor();
  }

  private static class NullArgumentToVariableArgVisitor
    extends BaseInspectionVisitor {

    @Override
    public void visitMethodCallExpression(
      @NotNull PsiMethodCallExpression call) {
      super.visitMethodCallExpression(call);

      if (!PsiUtil.isLanguageLevel5OrHigher(call)) {
        return;
      }
      final PsiExpressionList argumentList = call.getArgumentList();
      final PsiExpression[] args = argumentList.getExpressions();
      if (args.length == 0) {
        return;
      }
      final PsiExpression lastArg = args[args.length - 1];
      if (!ExpressionUtils.isNullLiteral(lastArg)) {
        return;
      }
      final PsiMethod method = call.resolveMethod();
      if (method == null) {
        return;
      }
      final PsiParameterList parameterList = method.getParameterList();
      if (parameterList.getParametersCount() != args.length) {
        return;
      }
      final PsiParameter[] parameters = parameterList.getParameters();
      final PsiParameter lastParameter =
        parameters[parameters.length - 1];
      if (!lastParameter.isVarArgs()) {
        return;
      }
      registerError(lastArg);
    }
  }
}