AssignmentToStaticFieldFromInstanceMethodInspection.java

/*
 * Copyright 2003-2015 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.assignment;

import com.intellij.psi.*;
import com.intellij.psi.tree.IElementType;
import com.intellij.psi.util.PsiTreeUtil;
import com.siyeh.InspectionGadgetsBundle;
import com.siyeh.ig.BaseInspection;
import com.siyeh.ig.BaseInspectionVisitor;
import org.jetbrains.annotations.NotNull;

public class AssignmentToStaticFieldFromInstanceMethodInspection
  extends BaseInspection {

  @Override
  @NotNull
  public String getDisplayName() {
    return InspectionGadgetsBundle.message(
      "assignment.to.static.field.from.instance.method.display.name");
  }

  @Override
  @NotNull
  public String buildErrorString(Object... infos) {
    return InspectionGadgetsBundle.message(
      "assignment.to.static.field.from.instance.method.problem.descriptor");
  }

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

  private static class AssignmentToStaticFieldFromInstanceMethodVisitor
    extends BaseInspectionVisitor {

    @Override
    public void visitAssignmentExpression(@NotNull PsiAssignmentExpression expression) {
      super.visitAssignmentExpression(expression);
      final PsiExpression lhs = expression.getLExpression();
      checkForStaticFieldAccess(lhs);
    }

    @Override
    public void visitPrefixExpression(@NotNull PsiPrefixExpression expression) {
      super.visitPrefixExpression(expression);
      final IElementType tokenType = expression.getOperationTokenType();
      if (!tokenType.equals(JavaTokenType.PLUSPLUS) &&
          !tokenType.equals(JavaTokenType.MINUSMINUS)) {
        return;
      }
      final PsiExpression operand = expression.getOperand();
      checkForStaticFieldAccess(operand);
    }

    @Override
    public void visitPostfixExpression(@NotNull PsiPostfixExpression expression) {
      super.visitPostfixExpression(expression);
      final IElementType tokenType = expression.getOperationTokenType();
      if (!tokenType.equals(JavaTokenType.PLUSPLUS) &&
          !tokenType.equals(JavaTokenType.MINUSMINUS)) {
        return;
      }
      final PsiExpression operand = expression.getOperand();
      checkForStaticFieldAccess(operand);
    }

    private void checkForStaticFieldAccess(PsiExpression expression) {
      if (!(expression instanceof PsiReferenceExpression)) {
        return;
      }
      final PsiElement referent = ((PsiReference)expression).resolve();
      if (referent == null) {
        return;
      }
      if (!(referent instanceof PsiField)) {
        return;
      }
      final PsiField fieldReferenced = (PsiField)referent;
      if (!fieldReferenced.hasModifierProperty(PsiModifier.STATIC)) {
        return;
      }
      if (isInStaticMethod(expression)) {
        return;
      }
      registerError(expression);
    }

    private static boolean isInStaticMethod(PsiElement element) {
      final PsiMember member =
        PsiTreeUtil.getParentOfType(element,
                                    PsiMethod.class, PsiClassInitializer.class);
      if (member == null) {
        return false;
      }
      return member.hasModifierProperty(PsiModifier.STATIC);
    }
  }
}