libjava/classpath/javax/swing/text/DefaultFormatter.java

/* DefaultFormatter.java --
Copyright (C) 2005  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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WITHOUT ANY WARRANTY; without even the implied warranty of
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General Public License for more details.

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02110-1301 USA.

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making a combined work based on this library.  Thus, the terms and
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permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package javax.swing.text;

import java.io.Serializable;
import java.lang.reflect.Constructor;
import java.text.ParseException;

import javax.swing.JFormattedTextField;

/**
 * The <code>DefaultFormatter</code> is a concrete formatter for use in
 * {@link JFormattedTextField}s.
 *
 * It can format arbitrary values by invoking
 * their {@link Object#toString} method.
 *
 * In order to convert a String back to
 * a value, the value class must provide a single argument constructor that
 * takes a String object as argument value. If no such constructor is found,
 * the String itself is passed back by #stringToValue.
 *
 * @author Roman Kennke (roman@kennke.org)
 */
public class DefaultFormatter extends JFormattedTextField.AbstractFormatter
  implements Cloneable, Serializable
{

  /**
   * A {@link DocumentFilter} that intercepts modification of the
   * JFormattedTextField's Document and commits the value depending
   * on the value of the <code>commitsOnValidEdit</code> property.
   *
   */
  // FIXME: Handle allowsInvalid and overwriteMode properties
  private class FormatterDocumentFilter
    extends DocumentFilter
  {
    /**
     * Invoked when text is removed from a text component.
     *
     * @param bypass the FilterBypass to use to mutate the document
     * @param offset the start position of the modification
     * @param length the length of the removed text
     *
     * @throws BadLocationException if offset or lenght are invalid in
     *     the Document
     */
    public void remove(DocumentFilter.FilterBypass bypass, int offset,
                        int length)
      throws BadLocationException
    {
      super.remove(bypass, offset, length);
      checkValidInput();
      commitIfAllowed();
    }

    /**
     * Invoked when text is inserted into a text component.
     *
     * @param bypass the FilterBypass to use to mutate the document
     * @param offset the start position of the modification
     * @param text the inserted text
     * @param attributes the attributes of the inserted text
     *
     * @throws BadLocationException if offset or lenght are invalid in
     *     the Document
     */
    public void insertString(DocumentFilter.FilterBypass bypass, int offset,
                              String text, AttributeSet attributes)
      throws BadLocationException
    {
      if (overwriteMode == true)
        replace(bypass, offset, text.length(), text, attributes);
      else
        super.insertString(bypass, offset, text, attributes);
      checkValidInput();
      commitIfAllowed();
    }

    /**
     * Invoked when text is replaced in a text component.
     *
     * @param bypass the FilterBypass to use to mutate the document
     * @param offset the start position of the modification
     * @param length the length of the removed text
     * @param text the inserted text
     * @param attributes the attributes of the inserted text
     *
     * @throws BadLocationException if offset or lenght are invalid in
     *     the Document
     */
    public void replace(DocumentFilter.FilterBypass bypass, int offset,
                         int length, String text, AttributeSet attributes)
      throws BadLocationException
    {
      super.replace(bypass, offset, length, text, attributes);
      checkValidInput();
      commitIfAllowed();
    }

    /**
     * Commits the value to the JTextTextField if the property
     * <code>commitsOnValidEdit</code> is set to <code>true</code>.
     */
    private void commitIfAllowed()
    {
      if (commitsOnValidEdit == true)
        try
          {
            getFormattedTextField().commitEdit();
          }
        catch (ParseException ex)
          {
            // ignore invalid edits
          }
    }

    /**
     * Checks if the value in the input field is valid. If the
     * property allowsInvalid is set to <code>false</code>, then
     * the string in the input field is not allowed to be entered.
     */
    private void checkValidInput()
    {
      JFormattedTextField ftf = getFormattedTextField();
      try
        {
          Object newval = stringToValue(ftf.getText());
        }
      catch (ParseException ex)
        {
          if (!allowsInvalid)
            {
              // roll back the input if invalid edits are not allowed
              try
                {
                  ftf.setText(valueToString(ftf.getValue()));
                }
              catch (ParseException pe)
                {
                  // if that happens, something serious must be wrong
                  AssertionError ae;
                  ae = new AssertionError("values must be parseable");
                  ae.initCause(pe);
                  throw ae;
                }
            }
        }
    }
  }

  /** The serialization UID (compatible with JDK1.5). */
  private static final long serialVersionUID = -355018354457785329L;

  /**
   * Indicates if the value should be committed after every
   * valid modification of the Document.
   */
  boolean commitsOnValidEdit;

  /**
   * If <code>true</code> newly inserted characters overwrite existing
   * values, otherwise insertion is done the normal way.
   */
  boolean overwriteMode;

  /**
   * If <code>true</code> invalid edits are allowed for a limited
   * time.
   */
  boolean allowsInvalid;

  /**
   * The class that is used for values.
   */
  Class valueClass;

  /**
   * Creates a new instance of <code>DefaultFormatter</code>.
   */
  public DefaultFormatter()
  {
    commitsOnValidEdit = false;
    overwriteMode = true;
    allowsInvalid = true;
  }

  /**
   * Installs the formatter on the specified {@link JFormattedTextField}.
   *
   * This method does the following things:
   * <ul>
   * <li>Display the value of #valueToString in the
   *  <code>JFormattedTextField</code></li>
   * <li>Install the Actions from #getActions on the <code>JTextField</code>
   * </li>
   * <li>Install the DocumentFilter returned by #getDocumentFilter</li>
   * <li>Install the NavigationFilter returned by #getNavigationFilter</li>
   * </ul>
   *
   * This method is typically not overridden by subclasses. Instead override
   * one of the mentioned methods in order to customize behaviour.
   *
   * @param ftf the {@link JFormattedTextField} in which this formatter
   *     is installed
   */
  public void install(JFormattedTextField ftf)
  {
    super.install(ftf);
  }

  /**
   * Returns <code>true</code> if the value should be committed after
   * each valid modification of the input field, <code>false</code> if
   * it should never be committed by this formatter.
   *
   * @return the state of the <code>commitsOnValidEdit</code> property
   *
   * @see #setCommitsOnValidEdit
   */
  public boolean getCommitsOnValidEdit()
  {
    return commitsOnValidEdit;
  }

  /**
   * Sets the value of the <code>commitsOnValidEdit</code> property.
   *
   * @param commitsOnValidEdit the new state of the
   *     <code>commitsOnValidEdit</code> property
   *
   * @see #getCommitsOnValidEdit
   */
  public void setCommitsOnValidEdit(boolean commitsOnValidEdit)
  {
    this.commitsOnValidEdit = commitsOnValidEdit;
  }

  /**
   * Returns the value of the <code>overwriteMode</code> property.
   * If that is set to <code>true</code> then newly inserted characters
   * overwrite existing values, otherwise the characters are inserted like
   * normal. The default is <code>true</code>.
   *
   * @return the value of the <code>overwriteMode</code> property
   */
  public boolean getOverwriteMode()
  {
    return overwriteMode;
  }

  /**
   * Sets the value of the <code>overwriteMode</code> property.
   *
   * If that is set to <code>true</code> then newly inserted characters
   * overwrite existing values, otherwise the characters are inserted like
   * normal. The default is <code>true</code>.
   *
   * @param overwriteMode the new value for the <code>overwriteMode</code>
   *     property
   */
  public void setOverwriteMode(boolean overwriteMode)
  {
    this.overwriteMode = overwriteMode;
  }

  /**
   * Returns whether or not invalid edits are allowed or not. If invalid
   * edits are allowed, the JFormattedTextField may temporarily contain invalid
   * characters.
   *
   * @return the value of the allowsInvalid property
   */
  public boolean getAllowsInvalid()
  {
    return allowsInvalid;
  }

  /**
   * Sets the value of the <code>allowsInvalid</code> property.
   *
   * @param allowsInvalid the new value for the property
   *
   * @see #getAllowsInvalid()
   */
  public void setAllowsInvalid(boolean allowsInvalid)
  {
    this.allowsInvalid = allowsInvalid;
  }

  /**
   * Returns the class that is used for values. When Strings are converted
   * back to values, this class is used to create new value objects.
   *
   * @return the class that is used for values
   */
  public Class<?> getValueClass()
  {
    return valueClass;
  }

  /**
   * Sets the class that is used for values.
   *
   * @param valueClass the class that is used for values
   *
   * @see #getValueClass()
   */
  public void setValueClass(Class<?> valueClass)
  {
    this.valueClass = valueClass;
  }

  /**
   * Converts a String (from the JFormattedTextField input) to a value.
   * In order to achieve this, the formatter tries to instantiate an object
   * of the class returned by #getValueClass() using a single argument
   * constructor that takes a String argument. If such a constructor cannot
   * be found, the String itself is returned.
   *
   * @param string the string to convert
   *
   * @return the value for the string
   *
   * @throws ParseException if the string cannot be converted into
   *     a value object (e.g. invalid input)
   */
  public Object stringToValue(String string)
    throws ParseException
  {
    Object value = string;
    Class valueClass = getValueClass();
    if (valueClass == null)
      {
        JFormattedTextField jft = getFormattedTextField();
        if (jft != null)
          valueClass = jft.getValue().getClass();
      }
    if (valueClass != null)
      try
        {
          Constructor constr = valueClass.getConstructor
                                             (new Class[]{String.class});
          value = constr.newInstance(new Object[]{ string });
        }
      catch (NoSuchMethodException ex)
        {
          // leave value as string
        }
      catch (Exception ex)
        {
          throw new ParseException(string, 0);
        }
    return value;
  }

  /**
   * Converts a value object into a String. This is done by invoking the
   * {@link Object#toString()} method on the value.
   *
   * @param value the value to be converted
   *
   * @return the string representation of the value
   *
   * @throws ParseException if the value cannot be converted
   */
  public String valueToString(Object value)
    throws ParseException
  {
    if (value == null)
      return "";
    return value.toString();
  }

  /**
   * Creates and returns a clone of this DefaultFormatter.
   *
   * @return a clone of this object
   *
   * @throws CloneNotSupportedException not thrown here
   */
  public Object clone()
    throws CloneNotSupportedException
  {
    return super.clone();
  }

  /**
   * Returns the DocumentFilter that is used to restrict input.
   *
   * @return the DocumentFilter that is used to restrict input
   */
  protected DocumentFilter getDocumentFilter()
  {
    return new FormatterDocumentFilter();
  }
}