plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bugs/MismatchedCollectionQueryUpdateInspectionBase.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.bugs;

import com.intellij.psi.*;
import com.intellij.psi.tree.IElementType;
import com.intellij.psi.util.PsiTreeUtil;
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.CollectionUtils;
import com.siyeh.ig.psiutils.ParenthesesUtils;
import com.siyeh.ig.psiutils.VariableAccessUtils;
import com.siyeh.ig.ui.ExternalizableStringSet;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

public class MismatchedCollectionQueryUpdateInspectionBase extends BaseInspection {
  @SuppressWarnings({"PublicField"})
  public final ExternalizableStringSet queryNames =
    new ExternalizableStringSet("copyInto", "drainTo", "propertyNames", "save", "store", "write", "forEach", "replaceAll");
  @SuppressWarnings({"PublicField"})
  public final ExternalizableStringSet updateNames =
    new ExternalizableStringSet("add", "clear", "drainTo", "insert", "load", "offer", "poll", "push", "put", "remove", "replace",
                                "retain", "set", "take", "compute");

  private static boolean isEmptyCollectionInitializer(PsiExpression initializer) {
    if (!(initializer instanceof PsiNewExpression)) {
      return false;
    }
    final PsiNewExpression newExpression = (PsiNewExpression)initializer;
    final PsiExpressionList argumentList = newExpression.getArgumentList();
    if (argumentList == null) {
      return false;
    }
    final PsiExpression[] arguments = argumentList.getExpressions();
    for (final PsiExpression argument : arguments) {
      final PsiType argumentType = argument.getType();
      if (argumentType == null) {
        return false;
      }
      if (CollectionUtils.isCollectionClassOrInterface(argumentType)) {
        return false;
      }
      if (argumentType instanceof PsiArrayType) {
        return false;
      }
    }
    return true;
  }

  private static boolean collectionQueriedByAssignment(@NotNull PsiVariable variable, @NotNull PsiElement context) {
    final CollectionQueriedByAssignmentVisitor visitor = new CollectionQueriedByAssignmentVisitor(variable);
    context.accept(visitor);
    return visitor.mayBeQueried();
  }

  @Override
  @NotNull
  public String getID() {
    return "MismatchedQueryAndUpdateOfCollection";
  }

  @Override
  @NotNull
  public String getDisplayName() {
    return InspectionGadgetsBundle.message("mismatched.update.collection.display.name");
  }

  @Override
  @NotNull
  public String buildErrorString(Object... infos) {
    final boolean updated = ((Boolean)infos[0]).booleanValue();
    if (updated) {
      return InspectionGadgetsBundle.message("mismatched.update.collection.problem.descriptor.updated.not.queried");
    }
    else {
      return InspectionGadgetsBundle.message("mismatched.update.collection.problem.description.queried.not.updated");
    }
  }

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

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

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

  private static class CollectionQueriedByAssignmentVisitor extends JavaRecursiveElementVisitor {

    private boolean mayBeQueried = false;
    @NotNull private final PsiVariable variable;

    CollectionQueriedByAssignmentVisitor(@NotNull PsiVariable variable) {
      this.variable = variable;
    }

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

    @Override
    public void visitReferenceExpression(PsiReferenceExpression expression) {
      if (mayBeQueried) {
        return;
      }
      super.visitReferenceExpression(expression);
      final PsiElement parent = ParenthesesUtils.getParentSkipParentheses(expression);
      if (!(parent instanceof PsiPolyadicExpression)) {
        return;
      }
      final PsiPolyadicExpression polyadicExpression = (PsiPolyadicExpression)parent;
      final IElementType tokenType = polyadicExpression.getOperationTokenType();
      if (JavaTokenType.PLUS != tokenType) {
        return;
      }
      final PsiElement target = expression.resolve();
      if (!variable.equals(target)) {
        return;
      }
      final PsiType type = polyadicExpression.getType();
      if (type ==  null || !type.equalsToText(CommonClassNames.JAVA_LANG_STRING)) {
        return;
      }
      mayBeQueried = true; // query by concatenation ("" + list)
    }

    @Override
    public void visitAssignmentExpression(@NotNull PsiAssignmentExpression assignment) {
      if (mayBeQueried) {
        return;
      }
      super.visitAssignmentExpression(assignment);
      final PsiExpression lhs = assignment.getLExpression();
      if (!VariableAccessUtils.mayEvaluateToVariable(lhs, variable)) {
        return;
      }
      final PsiExpression rhs = assignment.getRExpression();
      if (isEmptyCollectionInitializer(rhs)) {
        return;
      }
      mayBeQueried = true;
    }

    public boolean mayBeQueried() {
      return mayBeQueried;
    }
  }

  private class MismatchedCollectionQueryUpdateVisitor extends BaseInspectionVisitor {

    @Override
    public void visitField(@NotNull PsiField field) {
      super.visitField(field);
      if (!field.hasModifierProperty(PsiModifier.PRIVATE)) {
        return;
      }
      final PsiClass containingClass = PsiUtil.getTopLevelClass(field);
      if (!checkVariable(field, containingClass)) {
        return;
      }
      final boolean written = collectionContentsAreUpdated(field, containingClass);
      final boolean read = collectionContentsAreQueried(field, containingClass);
      if (read == written) {
        return;
      }
      registerFieldError(field, Boolean.valueOf(written));
    }

    @Override
    public void visitLocalVariable(@NotNull PsiLocalVariable variable) {
      super.visitLocalVariable(variable);
      final PsiCodeBlock codeBlock = PsiTreeUtil.getParentOfType(variable, PsiCodeBlock.class);
      if (!checkVariable(variable, codeBlock)) {
        return;
      }
      final boolean written = collectionContentsAreUpdated(variable, codeBlock);
      final boolean read = collectionContentsAreQueried(variable, codeBlock);
      if (read != written) {
        registerVariableError(variable, Boolean.valueOf(written));
      }
    }

    private boolean checkVariable(PsiVariable variable, PsiElement context) {
      if (context == null) {
        return false;
      }
      final PsiType type = variable.getType();
      if (!CollectionUtils.isCollectionClassOrInterface(type)) {
        return false;
      }
      if (VariableAccessUtils.variableIsAssignedFrom(variable, context)) {
        return false;
      }
      if (VariableAccessUtils.variableIsReturned(variable, context)) {
        return false;
      }
      if (VariableAccessUtils.variableIsPassedAsMethodArgument(variable, context)) {
        return false;
      }
      return !VariableAccessUtils.variableIsUsedInArrayInitializer(variable, context);
    }

    private boolean collectionContentsAreUpdated(PsiVariable variable, PsiElement context) {
      if (collectionUpdateCalled(variable, context)) {
        return true;
      }
      final PsiExpression initializer = variable.getInitializer();
      if (initializer != null && !isEmptyCollectionInitializer(initializer)) {
        return true;
      }
      if (initializer instanceof PsiNewExpression) {
        final PsiNewExpression newExpression = (PsiNewExpression)initializer;
        final PsiAnonymousClass anonymousClass = newExpression.getAnonymousClass();
        if (anonymousClass != null) {
          if (collectionUpdateCalled(null, anonymousClass)) {
            return true;
          }
          final ThisPassedAsArgumentVisitor visitor = new ThisPassedAsArgumentVisitor();
          anonymousClass.accept(visitor);
          if (visitor.isPassed()) {
            return true;
          }
        }
      }
      return VariableAccessUtils.variableIsAssigned(variable, context);
    }

    private boolean collectionContentsAreQueried(PsiVariable variable, PsiElement context) {
      if (collectionQueryCalled(variable, context)) {
        return true;
      }
      final PsiExpression initializer = variable.getInitializer();
      if (initializer != null && !isEmptyCollectionInitializer(initializer)) {
        return true;
      }
      return collectionQueriedByAssignment(variable, context);
    }

    private boolean collectionQueryCalled(PsiVariable variable, PsiElement context) {
      final CollectionQueryCalledVisitor visitor = new CollectionQueryCalledVisitor(variable, queryNames);
      context.accept(visitor);
      return visitor.isQueried();
    }

    private boolean collectionUpdateCalled(@Nullable PsiVariable variable, PsiElement context) {
      final CollectionUpdateCalledVisitor visitor = new CollectionUpdateCalledVisitor(variable, updateNames);
      context.accept(visitor);
      return visitor.isUpdated();
    }
  }
}