/*******************************************************************************
 * Copyright (c) 2013, 2015 EclipseSource.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 ******************************************************************************/
package com.eclipsesource.json;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.Reader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import com.eclipsesource.json.JsonObject.Member;


/**
 * Represents a JSON object, a set of name/value pairs, where the names are strings and the values
 * are JSON values.
 * <p>
 * Members can be added using the <code>add(String, ...)</code> methods which accept instances of
 * {@link JsonValue}, strings, primitive numbers, and boolean values. To modify certain values of an
 * object, use the <code>set(String, ...)</code> methods. Please note that the <code>add</code>
 * methods are faster than <code>set</code> as they do not search for existing members. On the other
 * hand, the <code>add</code> methods do not prevent adding multiple members with the same name.
 * Duplicate names are discouraged but not prohibited by JSON.
 * </p>
 * <p>
 * Members can be accessed by their name using {@link #get(String)}. A list of all names can be
 * obtained from the method {@link #names()}. This class also supports iterating over the members in
 * document order using an {@link #iterator()} or an enhanced for loop:
 * </p>
 * <pre>
 * for (Member member : jsonObject) {
 *   String name = member.getName();
 *   JsonValue value = member.getValue();
 *   ...
 * }
 * </pre>
 * <p>
 * Even though JSON objects are unordered by definition, instances of this class preserve the order
 * of members to allow processing in document order and to guarantee a predictable output.
 * </p>
 * <p>
 * Note that this class is <strong>not thread-safe</strong>. If multiple threads access a
 * <code>JsonObject</code> instance concurrently, while at least one of these threads modifies the
 * contents of this object, access to the instance must be synchronized externally. Failure to do so
 * may lead to an inconsistent state.
 * </p>
 * <p>
 * This class is <strong>not supposed to be extended</strong> by clients.
 * </p>
 */
@SuppressWarnings("serial") // use default serial UID
public class JsonObject extends JsonValue implements Iterable<Member> {

  private final List<String> names;
  private final List<JsonValue> values;
  private transient HashIndexTable table;

  /**
   * Creates a new empty JsonObject.
   */
  public JsonObject() {
    names = new ArrayList<String>();
    values = new ArrayList<JsonValue>();
    table = new HashIndexTable();
  }

  /**
   * Creates a new JsonObject, initialized with the contents of the specified JSON object.
   *
   * @param object
   *          the JSON object to get the initial contents from, must not be <code>null</code>
   */
  public JsonObject(JsonObject object) {
    this(object, false);
  }

  private JsonObject(JsonObject object, boolean unmodifiable) {
    if (object == null) {
      throw new NullPointerException("object is null");
    }
    if (unmodifiable) {
      names = Collections.unmodifiableList(object.names);
      values = Collections.unmodifiableList(object.values);
    } else {
      names = new ArrayList<String>(object.names);
      values = new ArrayList<JsonValue>(object.values);
    }
    table = new HashIndexTable();
    updateHashIndex();
  }

  /**
   * Reads a JSON object from the given reader.
   * <p>
   * Characters are read in chunks and buffered internally, therefore wrapping an existing reader in
   * an additional <code>BufferedReader</code> does <strong>not</strong> improve reading
   * performance.
   * </p>
   *
   * @param reader
   *          the reader to read the JSON object from
   * @return the JSON object that has been read
   * @throws IOException
   *           if an I/O error occurs in the reader
   * @throws ParseException
   *           if the input is not valid JSON
   * @throws UnsupportedOperationException
   *           if the input does not contain a JSON object
   * @deprecated Use {@link Json#parse(Reader)}{@link JsonValue#asObject() .asObject()} instead
   */
  @Deprecated
  public static JsonObject readFrom(Reader reader) throws IOException {
    return JsonValue.readFrom(reader).asObject();
  }

  /**
   * Reads a JSON object from the given string.
   *
   * @param string
   *          the string that contains the JSON object
   * @return the JSON object that has been read
   * @throws ParseException
   *           if the input is not valid JSON
   * @throws UnsupportedOperationException
   *           if the input does not contain a JSON object
   * @deprecated Use {@link Json#parse(String)}{@link JsonValue#asObject() .asObject()} instead
   */
  @Deprecated
  public static JsonObject readFrom(String string) {
    return JsonValue.readFrom(string).asObject();
  }

  /**
   * Returns an unmodifiable JsonObject for the specified one. This method allows to provide
   * read-only access to a JsonObject.
   * <p>
   * The returned JsonObject is backed by the given object and reflect changes that happen to it.
   * Attempts to modify the returned JsonObject result in an
   * <code>UnsupportedOperationException</code>.
   * </p>
   *
   * @param object
   *          the JsonObject for which an unmodifiable JsonObject is to be returned
   * @return an unmodifiable view of the specified JsonObject
   */
  public static JsonObject unmodifiableObject(JsonObject object) {
    return new JsonObject(object, true);
  }

  /**
   * Appends a new member to the end of this object, with the specified name and the JSON
   * representation of the specified <code>int</code> value.
   * <p>
   * This method <strong>does not prevent duplicate names</strong>. Calling this method with a name
   * that already exists in the object will append another member with the same name. In order to
   * replace existing members, use the method <code>set(name, value)</code> instead. However,
   * <strong> <em>add</em> is much faster than <em>set</em></strong> (because it does not need to
   * search for existing members). Therefore <em>add</em> should be preferred when constructing new
   * objects.
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add
   * @return the object itself, to enable method chaining
   */
  public JsonObject add(String name, int value) {
    add(name, Json.value(value));
    return this;
  }

  /**
   * Appends a new member to the end of this object, with the specified name and the JSON
   * representation of the specified <code>long</code> value.
   * <p>
   * This method <strong>does not prevent duplicate names</strong>. Calling this method with a name
   * that already exists in the object will append another member with the same name. In order to
   * replace existing members, use the method <code>set(name, value)</code> instead. However,
   * <strong> <em>add</em> is much faster than <em>set</em></strong> (because it does not need to
   * search for existing members). Therefore <em>add</em> should be preferred when constructing new
   * objects.
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add
   * @return the object itself, to enable method chaining
   */
  public JsonObject add(String name, long value) {
    add(name, Json.value(value));
    return this;
  }

  /**
   * Appends a new member to the end of this object, with the specified name and the JSON
   * representation of the specified <code>float</code> value.
   * <p>
   * This method <strong>does not prevent duplicate names</strong>. Calling this method with a name
   * that already exists in the object will append another member with the same name. In order to
   * replace existing members, use the method <code>set(name, value)</code> instead. However,
   * <strong> <em>add</em> is much faster than <em>set</em></strong> (because it does not need to
   * search for existing members). Therefore <em>add</em> should be preferred when constructing new
   * objects.
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add
   * @return the object itself, to enable method chaining
   */
  public JsonObject add(String name, float value) {
    add(name, Json.value(value));
    return this;
  }

  /**
   * Appends a new member to the end of this object, with the specified name and the JSON
   * representation of the specified <code>double</code> value.
   * <p>
   * This method <strong>does not prevent duplicate names</strong>. Calling this method with a name
   * that already exists in the object will append another member with the same name. In order to
   * replace existing members, use the method <code>set(name, value)</code> instead. However,
   * <strong> <em>add</em> is much faster than <em>set</em></strong> (because it does not need to
   * search for existing members). Therefore <em>add</em> should be preferred when constructing new
   * objects.
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add
   * @return the object itself, to enable method chaining
   */
  public JsonObject add(String name, double value) {
    add(name, Json.value(value));
    return this;
  }

  /**
   * Appends a new member to the end of this object, with the specified name and the JSON
   * representation of the specified <code>boolean</code> value.
   * <p>
   * This method <strong>does not prevent duplicate names</strong>. Calling this method with a name
   * that already exists in the object will append another member with the same name. In order to
   * replace existing members, use the method <code>set(name, value)</code> instead. However,
   * <strong> <em>add</em> is much faster than <em>set</em></strong> (because it does not need to
   * search for existing members). Therefore <em>add</em> should be preferred when constructing new
   * objects.
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add
   * @return the object itself, to enable method chaining
   */
  public JsonObject add(String name, boolean value) {
    add(name, Json.value(value));
    return this;
  }

  /**
   * Appends a new member to the end of this object, with the specified name and the JSON
   * representation of the specified string.
   * <p>
   * This method <strong>does not prevent duplicate names</strong>. Calling this method with a name
   * that already exists in the object will append another member with the same name. In order to
   * replace existing members, use the method <code>set(name, value)</code> instead. However,
   * <strong> <em>add</em> is much faster than <em>set</em></strong> (because it does not need to
   * search for existing members). Therefore <em>add</em> should be preferred when constructing new
   * objects.
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add
   * @return the object itself, to enable method chaining
   */
  public JsonObject add(String name, String value) {
    add(name, Json.value(value));
    return this;
  }

  /**
   * Appends a new member to the end of this object, with the specified name and the specified JSON
   * value.
   * <p>
   * This method <strong>does not prevent duplicate names</strong>. Calling this method with a name
   * that already exists in the object will append another member with the same name. In order to
   * replace existing members, use the method <code>set(name, value)</code> instead. However,
   * <strong> <em>add</em> is much faster than <em>set</em></strong> (because it does not need to
   * search for existing members). Therefore <em>add</em> should be preferred when constructing new
   * objects.
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add, must not be <code>null</code>
   * @return the object itself, to enable method chaining
   */
  public JsonObject add(String name, JsonValue value) {
    if (name == null) {
      throw new NullPointerException("name is null");
    }
    if (value == null) {
      throw new NullPointerException("value is null");
    }
    table.add(name, names.size());
    names.add(name);
    values.add(value);
    return this;
  }

  /**
   * Sets the value of the member with the specified name to the JSON representation of the
   * specified <code>int</code> value. If this object does not contain a member with this name, a
   * new member is added at the end of the object. If this object contains multiple members with
   * this name, only the last one is changed.
   * <p>
   * This method should <strong>only be used to modify existing objects</strong>. To fill a new
   * object with members, the method <code>add(name, value)</code> should be preferred which is much
   * faster (as it does not need to search for existing members).
   * </p>
   *
   * @param name
   *          the name of the member to replace
   * @param value
   *          the value to set to the member
   * @return the object itself, to enable method chaining
   */
  public JsonObject set(String name, int value) {
    set(name, Json.value(value));
    return this;
  }

  /**
   * Sets the value of the member with the specified name to the JSON representation of the
   * specified <code>long</code> value. If this object does not contain a member with this name, a
   * new member is added at the end of the object. If this object contains multiple members with
   * this name, only the last one is changed.
   * <p>
   * This method should <strong>only be used to modify existing objects</strong>. To fill a new
   * object with members, the method <code>add(name, value)</code> should be preferred which is much
   * faster (as it does not need to search for existing members).
   * </p>
   *
   * @param name
   *          the name of the member to replace
   * @param value
   *          the value to set to the member
   * @return the object itself, to enable method chaining
   */
  public JsonObject set(String name, long value) {
    set(name, Json.value(value));
    return this;
  }

  /**
   * Sets the value of the member with the specified name to the JSON representation of the
   * specified <code>float</code> value. If this object does not contain a member with this name, a
   * new member is added at the end of the object. If this object contains multiple members with
   * this name, only the last one is changed.
   * <p>
   * This method should <strong>only be used to modify existing objects</strong>. To fill a new
   * object with members, the method <code>add(name, value)</code> should be preferred which is much
   * faster (as it does not need to search for existing members).
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add
   * @return the object itself, to enable method chaining
   */
  public JsonObject set(String name, float value) {
    set(name, Json.value(value));
    return this;
  }

  /**
   * Sets the value of the member with the specified name to the JSON representation of the
   * specified <code>double</code> value. If this object does not contain a member with this name, a
   * new member is added at the end of the object. If this object contains multiple members with
   * this name, only the last one is changed.
   * <p>
   * This method should <strong>only be used to modify existing objects</strong>. To fill a new
   * object with members, the method <code>add(name, value)</code> should be preferred which is much
   * faster (as it does not need to search for existing members).
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add
   * @return the object itself, to enable method chaining
   */
  public JsonObject set(String name, double value) {
    set(name, Json.value(value));
    return this;
  }

  /**
   * Sets the value of the member with the specified name to the JSON representation of the
   * specified <code>boolean</code> value. If this object does not contain a member with this name,
   * a new member is added at the end of the object. If this object contains multiple members with
   * this name, only the last one is changed.
   * <p>
   * This method should <strong>only be used to modify existing objects</strong>. To fill a new
   * object with members, the method <code>add(name, value)</code> should be preferred which is much
   * faster (as it does not need to search for existing members).
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add
   * @return the object itself, to enable method chaining
   */
  public JsonObject set(String name, boolean value) {
    set(name, Json.value(value));
    return this;
  }

  /**
   * Sets the value of the member with the specified name to the JSON representation of the
   * specified string. If this object does not contain a member with this name, a new member is
   * added at the end of the object. If this object contains multiple members with this name, only
   * the last one is changed.
   * <p>
   * This method should <strong>only be used to modify existing objects</strong>. To fill a new
   * object with members, the method <code>add(name, value)</code> should be preferred which is much
   * faster (as it does not need to search for existing members).
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add
   * @return the object itself, to enable method chaining
   */
  public JsonObject set(String name, String value) {
    set(name, Json.value(value));
    return this;
  }

  /**
   * Sets the value of the member with the specified name to the specified JSON value. If this
   * object does not contain a member with this name, a new member is added at the end of the
   * object. If this object contains multiple members with this name, only the last one is changed.
   * <p>
   * This method should <strong>only be used to modify existing objects</strong>. To fill a new
   * object with members, the method <code>add(name, value)</code> should be preferred which is much
   * faster (as it does not need to search for existing members).
   * </p>
   *
   * @param name
   *          the name of the member to add
   * @param value
   *          the value of the member to add, must not be <code>null</code>
   * @return the object itself, to enable method chaining
   */
  public JsonObject set(String name, JsonValue value) {
    if (name == null) {
      throw new NullPointerException("name is null");
    }
    if (value == null) {
      throw new NullPointerException("value is null");
    }
    int index = indexOf(name);
    if (index != -1) {
      values.set(index, value);
    } else {
      table.add(name, names.size());
      names.add(name);
      values.add(value);
    }
    return this;
  }

  /**
   * Removes a member with the specified name from this object. If this object contains multiple
   * members with the given name, only the last one is removed. If this object does not contain a
   * member with the specified name, the object is not modified.
   *
   * @param name
   *          the name of the member to remove
   * @return the object itself, to enable method chaining
   */
  public JsonObject remove(String name) {
    if (name == null) {
      throw new NullPointerException("name is null");
    }
    int index = indexOf(name);
    if (index != -1) {
      table.remove(index);
      names.remove(index);
      values.remove(index);
    }
    return this;
  }

  /**
   * Copies all members of the specified object into this object. When the specified object contains
   * members with names that also exist in this object, the existing values in this object will be
   * replaced by the corresponding values in the specified object.
   *
   * @param object
   *          the object to merge
   * @return the object itself, to enable method chaining
   */
  public JsonObject merge(JsonObject object) {
    if (object == null) {
      throw new NullPointerException("object is null");
    }
    for (Member member : object) {
      this.set(member.name, member.value);
    }
    return this;
  }

  /**
   * Returns the value of the member with the specified name in this object. If this object contains
   * multiple members with the given name, this method will return the last one.
   *
   * @param name
   *          the name of the member whose value is to be returned
   * @return the value of the last member with the specified name, or <code>null</code> if this
   *         object does not contain a member with that name
   */
  public JsonValue get(String name) {
    if (name == null) {
      throw new NullPointerException("name is null");
    }
    int index = indexOf(name);
    return index != -1 ? values.get(index) : null;
  }

  /**
   * Returns the <code>int</code> value of the member with the specified name in this object. If
   * this object does not contain a member with this name, the given default value is returned. If
   * this object contains multiple members with the given name, the last one will be picked. If this
   * member's value does not represent a JSON number or if it cannot be interpreted as Java
   * <code>int</code>, an exception is thrown.
   *
   * @param name
   *          the name of the member whose value is to be returned
   * @param defaultValue
   *          the value to be returned if the requested member is missing
   * @return the value of the last member with the specified name, or the given default value if
   *         this object does not contain a member with that name
   */
  public int getInt(String name, int defaultValue) {
    JsonValue value = get(name);
    return value != null ? value.asInt() : defaultValue;
  }

  /**
   * Returns the <code>long</code> value of the member with the specified name in this object. If
   * this object does not contain a member with this name, the given default value is returned. If
   * this object contains multiple members with the given name, the last one will be picked. If this
   * member's value does not represent a JSON number or if it cannot be interpreted as Java
   * <code>long</code>, an exception is thrown.
   *
   * @param name
   *          the name of the member whose value is to be returned
   * @param defaultValue
   *          the value to be returned if the requested member is missing
   * @return the value of the last member with the specified name, or the given default value if
   *         this object does not contain a member with that name
   */
  public long getLong(String name, long defaultValue) {
    JsonValue value = get(name);
    return value != null ? value.asLong() : defaultValue;
  }

  /**
   * Returns the <code>float</code> value of the member with the specified name in this object. If
   * this object does not contain a member with this name, the given default value is returned. If
   * this object contains multiple members with the given name, the last one will be picked. If this
   * member's value does not represent a JSON number or if it cannot be interpreted as Java
   * <code>float</code>, an exception is thrown.
   *
   * @param name
   *          the name of the member whose value is to be returned
   * @param defaultValue
   *          the value to be returned if the requested member is missing
   * @return the value of the last member with the specified name, or the given default value if
   *         this object does not contain a member with that name
   */
  public float getFloat(String name, float defaultValue) {
    JsonValue value = get(name);
    return value != null ? value.asFloat() : defaultValue;
  }

  /**
   * Returns the <code>double</code> value of the member with the specified name in this object. If
   * this object does not contain a member with this name, the given default value is returned. If
   * this object contains multiple members with the given name, the last one will be picked. If this
   * member's value does not represent a JSON number or if it cannot be interpreted as Java
   * <code>double</code>, an exception is thrown.
   *
   * @param name
   *          the name of the member whose value is to be returned
   * @param defaultValue
   *          the value to be returned if the requested member is missing
   * @return the value of the last member with the specified name, or the given default value if
   *         this object does not contain a member with that name
   */
  public double getDouble(String name, double defaultValue) {
    JsonValue value = get(name);
    return value != null ? value.asDouble() : defaultValue;
  }

  /**
   * Returns the <code>boolean</code> value of the member with the specified name in this object. If
   * this object does not contain a member with this name, the given default value is returned. If
   * this object contains multiple members with the given name, the last one will be picked. If this
   * member's value does not represent a JSON <code>true</code> or <code>false</code> value, an
   * exception is thrown.
   *
   * @param name
   *          the name of the member whose value is to be returned
   * @param defaultValue
   *          the value to be returned if the requested member is missing
   * @return the value of the last member with the specified name, or the given default value if
   *         this object does not contain a member with that name
   */
  public boolean getBoolean(String name, boolean defaultValue) {
    JsonValue value = get(name);
    return value != null ? value.asBoolean() : defaultValue;
  }

  /**
   * Returns the <code>String</code> value of the member with the specified name in this object. If
   * this object does not contain a member with this name, the given default value is returned. If
   * this object contains multiple members with the given name, the last one is picked. If this
   * member's value does not represent a JSON string, an exception is thrown.
   *
   * @param name
   *          the name of the member whose value is to be returned
   * @param defaultValue
   *          the value to be returned if the requested member is missing
   * @return the value of the last member with the specified name, or the given default value if
   *         this object does not contain a member with that name
   */
  public String getString(String name, String defaultValue) {
    JsonValue value = get(name);
    return value != null ? value.asString() : defaultValue;
  }

  /**
   * Returns the number of members (name/value pairs) in this object.
   *
   * @return the number of members in this object
   */
  public int size() {
    return names.size();
  }

  /**
   * Returns <code>true</code> if this object contains no members.
   *
   * @return <code>true</code> if this object contains no members
   */
  public boolean isEmpty() {
    return names.isEmpty();
  }

  /**
   * Returns a list of the names in this object in document order. The returned list is backed by
   * this object and will reflect subsequent changes. It cannot be used to modify this object.
   * Attempts to modify the returned list will result in an exception.
   *
   * @return a list of the names in this object
   */
  public List<String> names() {
    return Collections.unmodifiableList(names);
  }

  /**
   * Returns an iterator over the members of this object in document order. The returned iterator
   * cannot be used to modify this object.
   *
   * @return an iterator over the members of this object
   */
  public Iterator<Member> iterator() {
    final Iterator<String> namesIterator = names.iterator();
    final Iterator<JsonValue> valuesIterator = values.iterator();
    return new Iterator<JsonObject.Member>() {

      public boolean hasNext() {
        return namesIterator.hasNext();
      }

      public Member next() {
        String name = namesIterator.next();
        JsonValue value = valuesIterator.next();
        return new Member(name, value);
      }

      public void remove() {
        throw new UnsupportedOperationException();
      }

    };
  }

  @Override
  void write(JsonWriter writer) throws IOException {
    writer.writeObjectOpen();
    Iterator<String> namesIterator = names.iterator();
    Iterator<JsonValue> valuesIterator = values.iterator();
    if (namesIterator.hasNext()) {
      writer.writeMemberName(namesIterator.next());
      writer.writeMemberSeparator();
      valuesIterator.next().write(writer);
      while (namesIterator.hasNext()) {
        writer.writeObjectSeparator();
        writer.writeMemberName(namesIterator.next());
        writer.writeMemberSeparator();
        valuesIterator.next().write(writer);
      }
    }
    writer.writeObjectClose();
  }

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

  @Override
  public JsonObject asObject() {
    return this;
  }

  @Override
  public int hashCode() {
    int result = 1;
    result = 31 * result + names.hashCode();
    result = 31 * result + values.hashCode();
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj == null) {
      return false;
    }
    if (getClass() != obj.getClass()) {
      return false;
    }
    JsonObject other = (JsonObject)obj;
    return names.equals(other.names) && values.equals(other.values);
  }

  int indexOf(String name) {
    int index = table.get(name);
    if (index != -1 && name.equals(names.get(index))) {
      return index;
    }
    return names.lastIndexOf(name);
  }

  private synchronized void readObject(ObjectInputStream inputStream)
      throws IOException, ClassNotFoundException
  {
    inputStream.defaultReadObject();
    table = new HashIndexTable();
    updateHashIndex();
  }

  private void updateHashIndex() {
    int size = names.size();
    for (int i = 0; i < size; i++) {
      table.add(names.get(i), i);
    }
  }

  /**
   * Represents a member of a JSON object, a pair of a name and a value.
   */
  public static class Member {

    private final String name;
    private final JsonValue value;

    Member(String name, JsonValue value) {
      this.name = name;
      this.value = value;
    }

    /**
     * Returns the name of this member.
     *
     * @return the name of this member, never <code>null</code>
     */
    public String getName() {
      return name;
    }

    /**
     * Returns the value of this member.
     *
     * @return the value of this member, never <code>null</code>
     */
    public JsonValue getValue() {
      return value;
    }

    @Override
    public int hashCode() {
      int result = 1;
      result = 31 * result + name.hashCode();
      result = 31 * result + value.hashCode();
      return result;
    }

    /**
     * Indicates whether a given object is "equal to" this JsonObject. An object is considered equal
     * if it is also a <code>JsonObject</code> and both objects contain the same members <em>in
     * the same order</em>.
     * <p>
     * If two JsonObjects are equal, they will also produce the same JSON output.
     * </p>
     *
     * @param object
     *          the object to be compared with this JsonObject
     * @return <tt>true</tt> if the specified object is equal to this JsonObject, <code>false</code>
     *         otherwise
     */
    @Override
    public boolean equals(Object object) {
      if (this == object) {
        return true;
      }
      if (object == null) {
        return false;
      }
      if (getClass() != object.getClass()) {
        return false;
      }
      Member other = (Member)object;
      return name.equals(other.name) && value.equals(other.value);
    }

  }

  static class HashIndexTable {

    private final byte[] hashTable = new byte[32]; // must be a power of two

    public HashIndexTable() {
    }

    public HashIndexTable(HashIndexTable original) {
      System.arraycopy(original.hashTable, 0, hashTable, 0, hashTable.length);
    }

    void add(String name, int index) {
      int slot = hashSlotFor(name);
      if (index < 0xff) {
        // increment by 1, 0 stands for empty
        hashTable[slot] = (byte)(index + 1);
      } else {
        hashTable[slot] = 0;
      }
    }

    void remove(int index) {
      for (int i = 0; i < hashTable.length; i++) {
        if (hashTable[i] == index + 1) {
          hashTable[i] = 0;
        } else if (hashTable[i] > index + 1) {
          hashTable[i]--;
        }
      }
    }

    int get(Object name) {
      int slot = hashSlotFor(name);
      // subtract 1, 0 stands for empty
      return (hashTable[slot] & 0xff) - 1;
    }

    private int hashSlotFor(Object element) {
      return element.hashCode() & hashTable.length - 1;
    }

  }

}
