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A packaging of the IntelliJ Community Edition java-analysis-impl library. This is release number 1 of trunk branch 142.
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/*
 * Copyright 2000-2009 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.
 */

/*
 * Created by IntelliJ IDEA.
 * User: max
 * Date: Jan 28, 2002
 * Time: 6:31:08 PM
 * To change template for new class use
 * Code Style | Class Templates options (Tools | IDE Options).
 */
package com.intellij.codeInspection.dataFlow.value;

import com.intellij.codeInsight.NullableNotNullManager;
import com.intellij.codeInsight.daemon.impl.analysis.JavaGenericsUtil;
import com.intellij.codeInspection.dataFlow.DfaPsiUtil;
import com.intellij.codeInspection.dataFlow.Nullness;
import com.intellij.openapi.util.Comparing;
import com.intellij.openapi.util.Trinity;
import com.intellij.patterns.ElementPattern;
import com.intellij.psi.*;
import com.intellij.psi.util.PsiUtil;
import com.intellij.psi.util.TypeConversionUtil;
import com.intellij.util.SmartList;
import com.intellij.util.containers.MultiMap;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.List;

import static com.intellij.patterns.PsiJavaPatterns.*;

public class DfaVariableValue extends DfaValue {

  private static final ElementPattern MEMBER_OR_METHOD_PARAMETER =
    or(psiMember(), psiParameter().withSuperParent(2, psiMember()));

  public static class Factory {
    private final MultiMap,DfaVariableValue> myExistingVars = new MultiMap, DfaVariableValue>();
    private final DfaValueFactory myFactory;

    Factory(DfaValueFactory factory) {
      myFactory = factory;
    }

    public DfaVariableValue createVariableValue(PsiVariable myVariable, boolean isNegated) {
      PsiType varType = myVariable.getType();
      if (varType instanceof PsiEllipsisType) {
        varType = new PsiArrayType(((PsiEllipsisType)varType).getComponentType());
      }
      return createVariableValue(myVariable, varType, isNegated, null);
    }
    @NotNull
    public DfaVariableValue createVariableValue(@NotNull PsiModifierListOwner myVariable,
                                                @Nullable PsiType varType,
                                                boolean isNegated,
                                                @Nullable DfaVariableValue qualifier) {
      Trinity key = Trinity.create(isNegated, ((PsiNamedElement)myVariable).getName(), qualifier);
      for (DfaVariableValue aVar : myExistingVars.get(key)) {
        if (aVar.hardEquals(myVariable, varType, isNegated, qualifier)) return aVar;
      }

      DfaVariableValue result = new DfaVariableValue(myVariable, varType, isNegated, myFactory, qualifier);
      myExistingVars.putValue(key, result);
      while (qualifier != null) {
        qualifier.myDependents.add(result);
        qualifier = qualifier.getQualifier();
      }
      return result;
    }

    public List getAllQualifiedBy(DfaVariableValue value) {
      return value.myDependents;
    }

  }

  private final PsiModifierListOwner myVariable;
  private final PsiType myVarType;
  @Nullable private final DfaVariableValue myQualifier;
  private DfaVariableValue myNegatedValue;
  private final boolean myIsNegated;
  private Nullness myInherentNullability;
  private final DfaTypeValue myTypeValue;
  private final List myDependents = new SmartList();

  private DfaVariableValue(@NotNull PsiModifierListOwner variable, @Nullable PsiType varType, boolean isNegated, DfaValueFactory factory, @Nullable DfaVariableValue qualifier) {
    super(factory);
    myVariable = variable;
    myIsNegated = isNegated;
    myQualifier = qualifier;
    myVarType = varType;
    DfaValue typeValue = myFactory.createTypeValue(varType, Nullness.UNKNOWN);
    myTypeValue = typeValue instanceof DfaTypeValue ? (DfaTypeValue)typeValue : null;
    if (varType != null && !varType.isValid()) {
      PsiUtil.ensureValidType(varType, "Variable: " + variable + " of class " + variable.getClass());
    }
  }

  @Nullable
  public DfaTypeValue getTypeValue() {
    return myTypeValue;
  }

  @NotNull
  public PsiModifierListOwner getPsiVariable() {
    return myVariable;
  }

  @Nullable
  public PsiType getVariableType() {
    return myVarType;
  }

  public boolean isNegated() {
    return myIsNegated;
  }

  @Nullable
  public DfaVariableValue getNegatedValue() {
    return myNegatedValue;
  }

  @Override
  public DfaVariableValue createNegated() {
    if (myNegatedValue != null) {
      return myNegatedValue;
    }
    return myNegatedValue = myFactory.getVarFactory().createVariableValue(myVariable, myVarType, !myIsNegated, myQualifier);
  }

  @SuppressWarnings({"HardCodedStringLiteral"})
  public String toString() {
    return (myIsNegated ? "!" : "") + ((PsiNamedElement)myVariable).getName() + (myQualifier == null ? "" : "|" + myQualifier.toString());
  }

  private boolean hardEquals(PsiModifierListOwner psiVar, PsiType varType, boolean negated, DfaVariableValue qualifier) {
    return psiVar == myVariable &&
           Comparing.equal(TypeConversionUtil.erasure(varType), TypeConversionUtil.erasure(myVarType)) &&
           negated == myIsNegated &&
           (myQualifier == null ? qualifier == null : myQualifier.hardEquals(qualifier.getPsiVariable(), qualifier.getVariableType(),
                                                                             qualifier.isNegated(), qualifier.getQualifier()));
  }

  @Nullable
  public DfaVariableValue getQualifier() {
    return myQualifier;
  }

  public Nullness getInherentNullability() {
    if (myInherentNullability != null) {
      return myInherentNullability;
    }

    return myInherentNullability = calcInherentNullability();
  }

  private Nullness calcInherentNullability() {
    PsiModifierListOwner var = getPsiVariable();
    Nullness nullability = DfaPsiUtil.getElementNullability(getVariableType(), var);
    if (nullability != Nullness.UNKNOWN) {
      return nullability;
    }

    Nullness defaultNullability = myFactory.isUnknownMembersAreNullable() && MEMBER_OR_METHOD_PARAMETER.accepts(var) ? Nullness.NULLABLE : Nullness.UNKNOWN;

    if (var instanceof PsiParameter && var.getParent() instanceof PsiForeachStatement) {
      PsiExpression iteratedValue = ((PsiForeachStatement)var.getParent()).getIteratedValue();
      if (iteratedValue != null) {
        PsiType itemType = JavaGenericsUtil.getCollectionItemType(iteratedValue);
        if (itemType != null) {
          return DfaPsiUtil.getElementNullability(itemType, var);
        }
      }
    }

    if (var instanceof PsiField && DfaPsiUtil.isFinalField((PsiVariable)var) && myFactory.isHonorFieldInitializers()) {
      List initializers = DfaPsiUtil.findAllConstructorInitializers((PsiField)var);
      if (initializers.isEmpty()) {
        return defaultNullability;
      }

      boolean hasUnknowns = false;
      for (PsiExpression expression : initializers) {
        if (!(expression instanceof PsiReferenceExpression)) {
          hasUnknowns = true;
          continue;
        }
        PsiElement target = ((PsiReferenceExpression)expression).resolve();
        if (!(target instanceof PsiParameter)) {
          hasUnknowns = true;
          continue;
        }
        if (NullableNotNullManager.isNullable((PsiParameter)target)) {
          return Nullness.NULLABLE;
        }
        if (!NullableNotNullManager.isNotNull((PsiParameter)target)) {
          hasUnknowns = true;
        }
      }
      
      if (hasUnknowns) {
        if (DfaPsiUtil.isInitializedNotNull((PsiField)var)) {
          return Nullness.NOT_NULL;
        }
        return defaultNullability;
      }
      
      return Nullness.NOT_NULL;
    }

    return defaultNullability;
  }

  public boolean isFlushableByCalls() {
    if (myVariable instanceof PsiLocalVariable || myVariable instanceof PsiParameter) return false;
    if (myVariable instanceof PsiVariable && myVariable.hasModifierProperty(PsiModifier.FINAL)) {
      return myQualifier != null && myQualifier.isFlushableByCalls();
    }
    return true;
  }

  public boolean containsCalls() {
    return myVariable instanceof PsiMethod || myQualifier != null && myQualifier.containsCalls();
  }

}