plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/performance/ToArrayCallWithZeroLengthArrayArgumentInspectionBase.java

/*
 * Copyright 2000-2013 JetBrains s.r.o.
 *
 * 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.performance;

import com.intellij.psi.*;
import com.intellij.psi.util.InheritanceUtil;
import com.siyeh.InspectionGadgetsBundle;
import com.siyeh.ig.BaseInspection;
import com.siyeh.ig.BaseInspectionVisitor;
import com.siyeh.ig.psiutils.CollectionUtils;
import com.siyeh.ig.psiutils.ExpressionUtils;
import org.jetbrains.annotations.Nls;
import org.jetbrains.annotations.NonNls;
import org.jetbrains.annotations.NotNull;

public class ToArrayCallWithZeroLengthArrayArgumentInspectionBase extends BaseInspection {
  @Override
  @Nls
  @NotNull
  public String getDisplayName() {
    return InspectionGadgetsBundle.message(
      "to.array.call.with.zero.length.array.argument.display.name");
  }

  @Override
  @NotNull
  protected String buildErrorString(Object... infos) {
    final PsiExpression argument = (PsiExpression)infos[1];
    return InspectionGadgetsBundle.message(
      "to.array.call.with.zero.length.array.argument.problem.descriptor",
      argument.getText());
  }

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

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

  private static class ToArrayCallWithZeroLengthArrayArgument extends BaseInspectionVisitor {

    @Override
    public void visitMethodCallExpression(PsiMethodCallExpression expression) {
      super.visitMethodCallExpression(expression);
      final PsiReferenceExpression methodExpression = expression.getMethodExpression();
      @NonNls final String methodName = methodExpression.getReferenceName();
      if (!"toArray".equals(methodName)) {
        return;
      }
      final PsiExpressionList argumentList = expression.getArgumentList();
      final PsiExpression[] arguments = argumentList.getExpressions();
      if (arguments.length != 1) {
        return;
      }
      final PsiExpression argument = arguments[0];
      final PsiType type = argument.getType();
      if (!(type instanceof PsiArrayType)) {
        return;
      }
      if (type.getArrayDimensions() != 1) {
        return;
      }
      if (argument instanceof PsiReferenceExpression) {
        final PsiReferenceExpression referenceExpression = (PsiReferenceExpression)argument;
        final PsiElement element = referenceExpression.resolve();
        if (!(element instanceof PsiField)) {
          return;
        }
        final PsiField field = (PsiField)element;
        if (!CollectionUtils.isConstantEmptyArray(field)) {
          return;
        }
      }
      else if (!ExpressionUtils.isZeroLengthArrayConstruction(argument)) {
        return;
      }
      final PsiMethod method = expression.resolveMethod();
      if (method == null) {
        return;
      }
      final PsiClass containingClass = method.getContainingClass();
      if (!InheritanceUtil.isInheritor(containingClass, CommonClassNames.JAVA_UTIL_COLLECTION)) {
        return;
      }
      registerMethodCallError(expression, expression, argument);
    }
  }
}