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The Waikato Environment for Knowledge Analysis (WEKA), a machine learning workbench. This is the stable version. Apart from bugfixes, this version does not receive any other updates.

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/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see .
 */

/*
 * JSONNode.java
 * Copyright (C) 2009-2012 University of Waikato, Hamilton, New Zealand
 */

package weka.core.json;

import java_cup.runtime.DefaultSymbolFactory;
import java_cup.runtime.SymbolFactory;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import java.awt.BorderLayout;
import java.io.Reader;

/**
 * Container class for storing a
 * JSON data structure.
 * 
 * @author FracPete (fracpete at waikato dot ac dot nz)
 * @version $Revision: 12111 $
 */
public class JSONNode extends DefaultMutableTreeNode {

  /** for serialization. */
  private static final long serialVersionUID = -3047440914507883491L;

  /**
   * The type of a node.
   * 
   * @author FracPete (fracpete at waikato dot ac dot nz)
   * @version $Revision: 12111 $
   */
  public static enum NodeType {
    /** a primitive. */
    PRIMITIVE, /** an object with nested key-value pairs. */
    OBJECT, /** an array. */
    ARRAY
  }

  /** the name of the node. */
  protected String m_Name;

  /** the value of the node. */
  protected Object m_Value;

  /** the type of the node. */
  protected NodeType m_NodeType;

  /**
   * Initializes the root container.
   */
  public JSONNode() {
    this(null, NodeType.OBJECT);
  }

  /**
   * Initializes the primitive container.
   * 
   * @param name the name
   * @param value the primitive value
   */
  public JSONNode(String name, Boolean value) {
    this(name, value, NodeType.PRIMITIVE);
  }

  /**
   * Initializes the primitive container.
   * 
   * @param name the name
   * @param value the primitive value
   */
  public JSONNode(String name, Integer value) {
    this(name, value, NodeType.PRIMITIVE);
  }

  /**
   * Initializes the primitive container.
   * 
   * @param name the name
   * @param value the primitive value
   */
  public JSONNode(String name, Double value) {
    this(name, value, NodeType.PRIMITIVE);
  }

  /**
   * Initializes the primitive container.
   * 
   * @param name the name
   * @param value the primitive value
   */
  public JSONNode(String name, String value) {
    this(name, value, NodeType.PRIMITIVE);
  }

  /**
   * Initializes the object container with null value.
   * 
   * @param name the name
   * @param type the node type
   */
  protected JSONNode(String name, NodeType type) {
    this(name, null, type);
  }

  /**
   * Initializes the container.
   * 
   * @param name the name
   * @param value the primitive value
   * @param type the type of the node, null for primitives
   */
  protected JSONNode(String name, Object value, NodeType type) {
    super();

    m_Name = name;
    m_Value = value;
    m_NodeType = type;
  }

  /**
   * Checks whether the node is anonymous.
   * 
   * @return true if no name available
   */
  public boolean isAnonymous() {
    return (m_Name == null);
  }

  /**
   * Returns the name of the node.
   * 
   * @return the name, null for anonymous nodes
   */
  public String getName() {
    return m_Name;
  }

  /**
   * Returns the stored value.
   * 
   * @return the stored value, can be null
   */
  public Object getValue() {
    return getValue(null);
  }

  /**
   * Returns the stored value.
   * 
   * @param defValue the default value, if value is null
   * @return the stored value, can be null
   */
  public Object getValue(Object defValue) {
    if (m_Value == null) {
      return defValue;
    } else {
      if (m_Value instanceof String) {
        return unescape(m_Value.toString());
      } else {
        return m_Value;
      }
    }
  }

  /**
   * Returns whether the node stores a primitive value or a an array/object.
   * 
   * @return true if a primitive, false in case of an array/object
   */
  public boolean isPrimitive() {
    return (m_NodeType == NodeType.PRIMITIVE);
  }

  /**
   * Returns wether the node is an array.
   * 
   * @return true if the node is array container
   */
  public boolean isArray() {
    return (m_NodeType == NodeType.ARRAY);
  }

  /**
   * Returns wether the node is an object.
   * 
   * @return true if the node is object container
   */
  public boolean isObject() {
    return (m_NodeType == NodeType.OBJECT);
  }

  /**
   * Returns the type of the container.
   * 
   * @return the type
   */
  public NodeType getNodeType() {
    return m_NodeType;
  }

  /**
   * Adds a "null" child to the object.
   * 
   * @param name the name of the null value
   * @return the new node, or null if none added
   */
  public JSONNode addNull(String name) {
    return add(name, null, NodeType.PRIMITIVE);
  }

  /**
   * Adds a key-value child to the object.
   * 
   * @param name the name of the pair
   * @param value the value
   * @return the new node, or null if none added
   */
  public JSONNode addPrimitive(String name, Boolean value) {
    return add(name, value, NodeType.PRIMITIVE);
  }

  /**
   * Adds a key-value child to the object.
   * 
   * @param name the name of the pair
   * @param value the value
   * @return the new node, or null if none added
   */
  public JSONNode addPrimitive(String name, Integer value) {
    return add(name, value, NodeType.PRIMITIVE);
  }

  /**
   * Adds a key-value child to the object.
   * 
   * @param name the name of the pair
   * @param value the value
   * @return the new node, or null if none added
   */
  public JSONNode addPrimitive(String name, Double value) {
    return add(name, value, NodeType.PRIMITIVE);
  }

  /**
   * Adds a key-value child to the object.
   * 
   * @param name the name of the pair
   * @param value the value
   * @return the new node, or null if none added
   */
  public JSONNode addPrimitive(String name, String value) {
    return add(name, value, NodeType.PRIMITIVE);
  }

  /**
   * Adds an array child to the object.
   * 
   * @param name the name of the pair
   * @return the new node, or null if none added
   */
  public JSONNode addArray(String name) {
    return add(name, null, NodeType.ARRAY);
  }

  /**
   * Adds a null array element child to the array.
   * 
   * @return the new node, or null if none added
   */
  public JSONNode addNullArrayElement() {
    return add(null, null, NodeType.PRIMITIVE);
  }

  /**
   * Add a key-value object child into the array
   * 
   * @return the newly added node
   */
  public JSONNode addObjectArrayElement() {
    return add(null, null, NodeType.OBJECT);
  }

  /**
   * Adds an array element child to the array.
   * 
   * @param value the value of the element array
   * @return the new node, or null if none added
   */
  public JSONNode addArrayElement(Object value) {
    NodeType type;

    if (getNodeType() != NodeType.ARRAY) {
      return null;
    }

    type = null;

    if (value != null) {
      if (value instanceof Boolean) {
        type = NodeType.PRIMITIVE;
      } else if (value instanceof Integer) {
        type = NodeType.PRIMITIVE;
      } else if (value instanceof Double) {
        type = NodeType.PRIMITIVE;
      } else if (value instanceof String) {
        type = NodeType.PRIMITIVE;
      } else if (value.getClass().isArray()) {
        type = NodeType.ARRAY;
      } else {
        type = NodeType.OBJECT;
      }
    }

    return add(null, value, type);
  }

  /**
   * Adds an object child to the object.
   * 
   * @param name the name of the pair
   * @return the new node, or null if none added
   */
  public JSONNode addObject(String name) {
    return add(name, null, NodeType.OBJECT);
  }

  /**
   * Adds a key-value child to the object.
   * 
   * @param name the name of the pair
   * @param value the value
   * @param type the node type, null for primitives
   * @return the new node, or null if none added
   */
  protected JSONNode add(String name, Object value, NodeType type) {
    JSONNode child;

    if (isPrimitive()) {
      return null;
    }

    child = new JSONNode(name, value, type);
    add(child);

    return child;
  }

  /**
   * Checks whether the node has a child with the given name.
   * 
   * @param name the name of the child
   * @return true if child with that name is available
   */
  public boolean hasChild(String name) {
    return (getChild(name) != null);
  }

  /**
   * Returns the child with the given name.
   * 
   * @param name the name of the child
   * @return the child if available, null otherwise
   */
  public JSONNode getChild(String name) {
    JSONNode result;
    JSONNode node;
    int i;

    result = null;

    for (i = 0; i < getChildCount(); i++) {
      node = (JSONNode) getChildAt(i);
      if (!node.isAnonymous() && node.getName().equals(name)) {
        result = node;
        break;
      }
    }

    return result;
  }

  /**
   * Generates the indentation string.
   * 
   * @param level the level
   * @return the indentation string (tabs)
   */
  protected String getIndentation(int level) {
    StringBuffer result;
    int i;

    result = new StringBuffer();
    for (i = 0; i < level; i++) {
      result.append("\t");
    }

    return result.toString();
  }

  /**
   * Escapes ", \, /, \b, \f, \n, \r, \t in strings.
   * 
   * @param o the object to process (only strings get processed)
   * @return the processed object
   */
  protected Object escape(Object o) {
    if (o instanceof String) {
      return escape((String) o);
    } else {
      return o;
    }
  }

  /**
   * Escapes ", /, \b, \f, \n, \r, \t.
   *
   * @param s the string to process
   * @return the processed
   */
  protected String escape(String s) {
    StringBuffer result;
    int i;
    char c;

    // take care of already escaped characters first (like
    // \n in string literals
    // kind of ugly - probably a better way of handling this
    // somehow.
    s = s.replace("\\n", "@@-@@n").replace("\\r", "@@-@@r")
      .replace("\\t", "@@-@@t").replace("\\b", "@@-@@b")
      .replace("\\f", "@@-@@f");

    if ((s.indexOf('\"') > -1) || (s.indexOf('\\') > -1)
      || (s.indexOf('\b') > -1) || (s.indexOf('\f') > -1)
      || (s.indexOf('\n') > -1) || (s.indexOf('\r') > -1)
      || (s.indexOf('\t') > -1)) {
      result = new StringBuffer();
      for (i = 0; i < s.length(); i++) {
        c = s.charAt(i);
        if (c == '\"') {
          result.append("\\\"");
        } else if (c == '\\') {
          result.append("\\\\");
        } else if (c == '\b') {
          result.append("\\b");
        } else if (c == '\f') {
          result.append("\\f");
        } else if (c == '\n') {
          result.append("\\n");
        } else if (c == '\r') {
          result.append("\\r");
        } else if (c == '\t') {
          result.append("\\t");
        } else {
          result.append(c);
        }
      }
    } else {
      result = new StringBuffer(s);
    }

    return result.toString();
  }

  /**
   * Un-escapes ", /, \b, \f, \n, \r, \t.
   *
   * @param s the string to process
   * @return the processed string
   */
  protected String unescape(String s) {
    StringBuilder newStringBuffer;
    int index;

    // replace each of the following characters with the backquoted version
    String charsFind[] = { "\\\\", "\\'", "\\t", "\\n", "\\r", "\\b", "\\f",
      "\\\"", "\\%", "\\u001E" };
    char charsReplace[] =
      { '\\', '\'', '\t', '\n', '\r', '\b', '\f', '"', '%', '\u001E' };
    int pos[] = new int[charsFind.length];
    int curPos;

    String str = new String(s);
    newStringBuffer = new StringBuilder();
    while (str.length() > 0) {
      // get positions and closest character to replace
      curPos = str.length();
      index = -1;
      for (int i = 0; i < pos.length; i++) {
        pos[i] = str.indexOf(charsFind[i]);
        if ((pos[i] > -1) && (pos[i] < curPos)) {
          index = i;
          curPos = pos[i];
        }
      }

      // replace character if found, otherwise finished
      if (index == -1) {
        newStringBuffer.append(str);
        str = "";
      } else {
        newStringBuffer.append(str.substring(0, pos[index]));
        newStringBuffer.append(charsReplace[index]);
        str = str.substring(pos[index] + charsFind[index].length());
      }
    }

    return newStringBuffer.toString().replace("@@-@@", "\\");
  }

  /**
   * Dumps the node structure into JSON format.
   * 
   * @param buffer the buffer to add the data to
   */
  public void toString(StringBuffer buffer) {
    int level;
    boolean isLast;
    String indent;
    int i;

    level = getLevel();
    isLast = (getNextSibling() == null);
    indent = getIndentation(level);

    buffer.append(indent);
    if (m_Name != null) {
      buffer.append("\"");
      buffer.append(escape(m_Name));
      buffer.append("\" : ");
    }

    if (isObject()) {
      buffer.append("{\n");
      for (i = 0; i < getChildCount(); i++) {
        ((JSONNode) getChildAt(i)).toString(buffer);
      }
      buffer.append(indent);
      buffer.append("}");
    } else if (isArray()) {
      buffer.append("[\n");
      for (i = 0; i < getChildCount(); i++) {
        ((JSONNode) getChildAt(i)).toString(buffer);
      }
      buffer.append(indent);
      buffer.append("]");
    } else {
      if (m_Value == null) {
        buffer.append("null");
      } else if (m_Value instanceof String) {
        buffer.append("\"");
        buffer.append(escape((String) m_Value));
        buffer.append("\"");
      } else {
        buffer.append(m_Value.toString());
      }
    }

    if (!isLast) {
      buffer.append(",");
    }
    buffer.append("\n");
  }

  /**
   * Returns a string representation of the node.
   * 
   * @return the string representation
   */
  @Override
  public String toString() {
    String result;

    result = null;

    if (isObject()) {
      if (isRoot()) {
        result = "JSON";
      } else if (m_Name == null) {
        result = "";
      } else {
        result = escape(m_Name) + " (Object)";
      }
    } else if (isArray()) {
      if (m_Name == null) {
        result = "";
      } else {
        result = escape(m_Name) + " (Array)";
      }
    } else {
      if (m_Name != null) {
        result = escape(m_Name) + ": " + escape(m_Value);
      } else {
        result = "" + m_Value;
      }
    }

    return result;
  }

  /**
   * Reads the JSON object from the given reader.
   * 
   * @param reader the reader to read the JSON object from
   * @return the generated JSON object
   * @throws Exception if parsing fails
   */
  @SuppressWarnings("deprecation")
  public static JSONNode read(Reader reader) throws Exception {
    SymbolFactory sf;
    Parser parser;

    sf = new DefaultSymbolFactory();
    parser = new Parser(new Scanner(reader, sf), sf);
    parser.parse();

    return parser.getResult();
  }

  /**
   * Only for testing. Generates a simple JSON object and displays it.
   * 
   * @param args ignored
   * @throws Exception if something goes wrong
   */
  public static void main(String[] args) throws Exception {
    // generates the example listed here:
    // http://en.wikipedia.org/wiki/JSON
    JSONNode person = new JSONNode();
    person.addPrimitive("firstName", "John");
    person.addPrimitive("lastName", "Smith");
    JSONNode address = person.addObject("address");
    address.addPrimitive("streetAddress", "21 2nd Street");
    address.addPrimitive("city", "New York");
    address.addPrimitive("state", "NY");
    address.addPrimitive("postalCode", 10021);
    JSONNode phonenumbers = person.addArray("phoneNumbers");
    phonenumbers.addArrayElement("212 555-1234");
    phonenumbers.addArrayElement("646 555-4567");

    // output in console
    StringBuffer buffer = new StringBuffer();
    person.toString(buffer);
    System.out.println(buffer.toString());

    // display GUI
    JTree tree = new JTree(person);
    JFrame frame = new JFrame("JSON");
    frame.setSize(800, 600);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().setLayout(new BorderLayout());
    frame.getContentPane().add(new JScrollPane(tree), BorderLayout.CENTER);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}
 















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