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/*
 * Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
 *
 * 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. See accompanying
 * LICENSE file.
 */
package com.gemstone.gemfire.cache.query.internal;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.*;

import com.gemstone.gnu.trove.*;
import com.gemstone.gemfire.internal.DataSerializableFixedID;
import com.gemstone.gemfire.DataSerializer;
import com.gemstone.gemfire.cache.query.*;
import com.gemstone.gemfire.cache.query.types.*;
import com.gemstone.gemfire.cache.query.internal.types.*;
import com.gemstone.gemfire.internal.i18n.LocalizedStrings;
import com.gemstone.gemfire.internal.shared.Version;

/**
 * A Set constrained to contain Structs of all the same type. To conserve on
 * objects, we store the StructType once and reuse it to generate Struct
 * instances on demand.
 * 
 * The values in this set are stored as Object[] and get wrapped in Structs as
 * necessary.
 * 
 * @author Eric Zoerner
 * @since 4.0
 */
public final class StructSet extends THashSet implements SelectResults, DataSerializableFixedID {
  private static final long serialVersionUID = -1228835506930611510L;

  protected StructType structType;
  /**
   * Holds value of property modifiable.
   */
  private boolean modifiable = true;
  
  /**
   * Empty constructor to satisfy DataSerializer requirements
   */
  public StructSet() {  
  }
  
  /**
   * This implementation uses Arrays.equals(Object[]) as it hashing strategy.
   */
  protected static class ObjectArrayHashingStrategy implements TObjectHashingStrategy {
private static final long serialVersionUID = -6407549977968716071L;

    public final int computeHashCode(Object o) {
      // throws ClassCastException if not Object[]
      // compute hash code based on all elements
      Object[] oa = (Object[]) o;
      int h = 0;
      for (int i = 0; i < oa.length; i++) {
        Object obj = oa[i];
        if (obj != null) h += obj.hashCode();
      }
      return h;
    }

    public final boolean equals(Object o1, Object o2) {
      // throws ClassCastException if not Object[]
    	if (o1 == null) return o2 == null;
        if (!(o1 instanceof Object[]) || !(o2 instanceof Object[])) {
          return o1.equals(o2);
        } 
      return Arrays.equals((Object[]) o1, (Object[]) o2);
    }
  }

  /** Creates a new instance of StructSet */
  public StructSet(StructType structType) {
    super(new ObjectArrayHashingStrategy());
    if (structType == null) { throw new IllegalArgumentException(LocalizedStrings.StructSet_STRUCTTYPE_MUST_NOT_BE_NULL.toLocalizedString()); }
    this.structType = structType;
  }

  /** takes collection of Object[] fieldValues *or* another StructSet */
  public StructSet(Collection c, StructType structType) {
    super(c, new ObjectArrayHashingStrategy());
    if (structType == null) { throw new IllegalArgumentException(LocalizedStrings.StructSet_STRUCTTYPE_MUST_NOT_BE_NULL.toLocalizedString()); }
    this.structType = structType;
  }

  /** Creates a StructSet directly from a StructBag;
   *  (internal use) 
   *  @since 5.1
   */
  StructSet(StructBag bag) {
    super(new ObjectArrayHashingStrategy());
    this.structType = (StructType)bag.elementType;
    if (bag.hasLimitIterator) {
      // Asif: Since the number of unique keys which
      // will be returned by Bag with limit in place
      // cannot be more than the size of the bag ( i.e
      // the limit) , we can safely assume HashMap size
      // to equal to bag's size
      ensureCapacity(bag.size());
      Iterator itr = bag.fieldValuesIterator();
      while (itr.hasNext()) {
        addFieldValues((Object[])itr.next());
      }
    }
    else {
      TObjectIntIterator itr = bag.map.iterator();
      ensureCapacity(bag.map.size());
      while (itr.hasNext()) {
        itr.advance();
        addFieldValues((Object[])itr.key());
      }
    }
  }

  public StructSet(int initialCapacity, StructType structType) {
    super(initialCapacity, new ObjectArrayHashingStrategy());
    if (structType == null) { throw new IllegalArgumentException(LocalizedStrings.StructSet_STRUCTTYPE_MUST_NOT_BE_NULL.toLocalizedString()); }
    this.structType = structType;
  }

  public StructSet(int initialCapacity, float loadFactor, StructType structType) {
    super(initialCapacity, loadFactor, new ObjectArrayHashingStrategy());
    if (structType == null) { throw new IllegalArgumentException(LocalizedStrings.StructSet_STRUCTTYPE_MUST_NOT_BE_NULL.toLocalizedString()); }
    this.structType = structType;
  }


  @Override
  public boolean equals(Object other) {
    if (!(other instanceof StructSet)) {
      return false;
    }
    if (!this.structType.equals(((StructSet)other).structType)) {
      return false;
    }
    return super.equals(other);
  }
  
  @Override
  public int hashCode() {
    return this.structType.hashCode();
  }
  
  
  /** Add a Struct */
  @Override
  public boolean add(Object obj) {
    if (!(obj instanceof StructImpl)) { throw new IllegalArgumentException(LocalizedStrings.StructSet_THIS_SET_ONLY_ACCEPTS_STRUCTIMPL.toLocalizedString()); }
    StructImpl s = (StructImpl) obj;
    if (!s.getStructType().equals(this.structType)) {
      throw new IllegalArgumentException(LocalizedStrings.StructSet_OBJ_DOES_NOT_HAVE_THE_SAME_STRUCTTYPE_REQUIRED_0_ACTUAL_1.toLocalizedString(new Object[] {this.structType, s.getStructType()}));
    }
    return addFieldValues(s.getFieldValues());
  }

  /**
   * For internal use. Just add the Object[] values for a struct with same type
   */
  public boolean addFieldValues(Object[] fieldValues) {
    return super.add(fieldValues);
  }

  /** Does this set contain specified struct? */
  @Override
  public boolean contains(Object obj) {
    if (!(obj instanceof Struct)) { return false; }
    Struct s = (Struct) obj;
    if (!this.structType.equals(StructTypeImpl.typeFromStruct(s))) { return false; }
    return containsFieldValues(s.getFieldValues());
  }

  /**
   * Does this set contain a Struct of the correct type with the specified
   * values?
   */
  public boolean containsFieldValues(Object[] fieldValues) {
    return super.contains(fieldValues);
  }

  /** Remove the specified Struct */
  @Override
  public boolean remove(Object o) {
    if (!(o instanceof Struct)) { return false; }
    Struct s = (Struct) o;
    if (!this.structType.equals(StructTypeImpl.typeFromStruct(s))) { return false; }
    return removeFieldValues(s.getFieldValues());
  }

  /** Remove the field values from a struct of the correct type */
  public boolean removeFieldValues(Object[] fieldValues) {
    return super.remove(fieldValues);
  }

  // downcast StructSets to call more efficient methods
  @Override
  public boolean addAll(Collection c) {
    if (c instanceof StructSet) { return addAll((StructSet) c); }
    return super.addAll(c);
  }

  @Override
  public boolean removeAll(Collection c) {
    if (c instanceof StructSet) { return removeAll((StructSet) c); }
    return super.removeAll(c);
  }

  @Override
  public boolean retainAll(Collection c) {
    if (c instanceof StructSet) { return retainAll((StructSet) c); }
    return super.retainAll(c);
  }

  public boolean addAll(StructSet ss) {
    boolean modified = false;
    if (!this.structType.equals(ss.structType)) { throw new IllegalArgumentException(LocalizedStrings.StructSet_TYPES_DONT_MATCH.toLocalizedString()); }
    for (Iterator itr = ss.fieldValuesIterator(); itr.hasNext();) {
      Object[] vals = (Object[]) itr.next();
      if (super.add(vals)) {
        modified = true;
      }
    }
    return modified;
  }

  public boolean removeAll(StructSet ss) {
    boolean modified = false;
    if (!this.structType.equals(ss.structType)) { return false; // nothing
                                                                // modified
    }
    for (Iterator itr = ss.fieldValuesIterator(); itr.hasNext();) {
      Object[] vals = (Object[]) itr.next();
      if (super.remove(vals)) {
        modified = true;
      }
    }
    return modified;
  }

  public boolean retainAll(StructSet ss) {
    if (!this.structType.equals(ss.structType)) {
      if (isEmpty()) {
        return false; // nothing modified
      }
      else {
        clear();
        return true; // nothing retained in receiver collection
      }
    }
    boolean changed = false;
    int size = size();
    Iterator it;
    it = fieldValuesIterator();
    while (size-- > 0) {
      Object[] vals = (Object[]) it.next();
      if (!ss.containsFieldValues(vals)) {
        it.remove();
        changed = true;
      }
    }
    return changed;
  }

  /** Returns an Iterator over the Structs in this set */
  @Override
  public Iterator iterator() {
    return new StructIterator(fieldValuesIterator());
  }

  /** Returns an iterator over the fieldValues Object[] instances */
  public Iterator fieldValuesIterator() {
    return super.iterator();
  }

  public CollectionType getCollectionType() {
    return new CollectionTypeImpl(java.util.Set.class, this.structType);
  }

  // note: this method is dangerous in that it could result in undefined
  // behavior if the new struct type is not compatible with the data.
  // For now just trust that the application knows what it is doing if it
  // is overriding the element type in a set of structs
  public void setElementType(ObjectType elementType) {
    if (!(elementType instanceof StructTypeImpl)) { throw new IllegalArgumentException(LocalizedStrings.StructSet_ELEMENT_TYPE_MUST_BE_STRUCT.toLocalizedString()); }
    this.structType = (StructType) elementType;
  }

  public List asList() {
    return new ArrayList(this);
  }

  public Set asSet() {
    return this;
  }

  /**
   * Getter for property modifiable.
   * 
   * @return Value of property modifiable.
   */
  public boolean isModifiable() {
    return this.modifiable;
  }

  public int occurrences(Object element) {
    return contains(element) ? 1 : 0;
  }
  
  /**
   * Setter for property modifiable.
   * 
   * @param modifiable New value of property modifiable.
   */
  public void setModifiable(boolean modifiable) {
    this.modifiable = modifiable;
  }

  @Override
  public String toString() {
    StringBuffer buf = new StringBuffer();
    buf.append("[");
    Iterator i = iterator();
    boolean hasNext = i.hasNext();
    while (hasNext) {
      Object o = i.next();
      buf.append(o == this ? "(this Collection)" : String.valueOf(o));
      hasNext = i.hasNext();
      if (hasNext) buf.append(", ");
    }
    buf.append("]");
    return buf.toString();
  }

  /**
   * Iterator wrapper to construct Structs on demand.
   */
  private class StructIterator implements Iterator {

    private final Iterator itr;

    /**
     * @param itr iterator over the Object[] instances of fieldValues
     */
    StructIterator(Iterator itr) {
      this.itr = itr;
    }

    public boolean hasNext() {
      return this.itr.hasNext();
    }

    public Object next() {
      return new StructImpl((StructTypeImpl)StructSet.this.structType, (Object[]) this.itr.next());
    }

    public void remove() {
      this.itr.remove();
    }
  }
  
  public int getDSFID() {
    return STRUCT_SET;
  }

  public void fromData(DataInput in) throws IOException, ClassNotFoundException
  {
    int size = in.readInt();
    this.structType = (StructTypeImpl)DataSerializer.readObject(in);
    for (int j = size; j > 0; j--) {
      this.add(DataSerializer.readObject(in));
    }
  }

  public void toData(DataOutput out) throws IOException
  {    
    out.writeInt(this.size());
    DataSerializer.writeObject(this.structType, out);
    for (Iterator i = this.iterator(); i.hasNext();) {
      DataSerializer.writeObject(i.next(), out);
    }
  }

  @Override
  public Version[] getSerializationVersions() {
    return null;
  }
}




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