gcc/libjava/classpath/javax/swing/text/InternationalFormatter.java

/* InternationalFormatter.java --
Copyright (C) 2005, 2006  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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General Public License for more details.

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02110-1301 USA.

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permission to link this library with independent modules to produce an
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package javax.swing.text;

import java.text.AttributedCharacterIterator;
import java.text.Format;
import java.text.ParseException;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import javax.swing.Action;
import javax.swing.JFormattedTextField;

/**
 * This extends {@link DefaultFormatter} so that the value to string
 * conversion is done via a {@link Format} object. This allows
 * various additional formats to be handled by JFormattedField.
 *
 * @author Roman Kennke (roman@kennke.org)
 */
public class InternationalFormatter
  extends DefaultFormatter
{
  /** The serialization UID (compatible with JDK1.5). */
  private static final long serialVersionUID = 2436068675711756856L;

  /** The format that handles value to string conversion. */
  Format format;

  /** The minimal permissable value. */
  Comparable minimum;

  /** The maximal permissable value. */
  Comparable maximum;

  /**
   * Creates a new InternationalFormatter with no Format specified.
   */
  public InternationalFormatter()
  {
    super();
    minimum = null;
    maximum = null;
    format = null;
    setCommitsOnValidEdit(false);
    setOverwriteMode(false);
  }

  /**
   * Creates a new InternationalFormatter that uses the specified
   * Format object for value to string conversion.
   *
   * @param format the Format object to use for value to string conversion
   */
  public InternationalFormatter(Format format)
  {
    this();
    setFormat(format);
  }

  /**
   * Sets the Format object that is used to convert values to strings.
   *
   * @param format the Format to use for value to string conversion
   *
   * @see Format
   */
  public void setFormat(Format format)
  {
    this.format = format;
  }

  /**
   * Returns the currently used Format object that is used to format
   * the JFormattedField.
   *
   * @return the current Format
   */
  public Format getFormat()
  {
    return format;
  }

  /**
   * Sets the minimum value that is allowed by this Formatter. The minimum
   * value is given as an object that implements the {@link Comparable}
   * interface.
   *
   * If <code>minValue</code> is null, then the Formatter has no restrictions
   * at the lower end.
   *
   * If value class is not yet specified and <code>minValue</code> is not
   * null, then <code>valueClass</code> is set to the class of the minimum
   * value.
   *
   * @param minValue the minimum permissable value
   *
   * @see Comparable
   */
  public void setMinimum(Comparable minValue)
  {
    minimum = minValue;
    if (valueClass == null && minValue != null)
      valueClass = minValue.getClass();
  }

  /**
   * Returns the minimal value that is allowed by this Formatter.
   *
   * A <code>null</code> value means that there is no restriction.
   *
   * @return the minimal value that is allowed by this Formatter or
   *     <code>null</code> if there is no restriction
   */
  public Comparable getMinimum()
  {
    return minimum;
  }

  /**
   * Sets the maximum value that is allowed by this Formatter. The maximum
   * value is given as an object that implements the {@link Comparable}
   * interface.
   *
   * If <code>maxValue</code> is null, then the Formatter has no restrictions
   * at the upper end.
   *
   * If value class is not yet specified and <code>maxValue</code> is not
   * null, then <code>valueClass</code> is set to the class of the maximum
   * value.
   *
   * @param maxValue the maximum permissable value
   *
   * @see Comparable
   */
  public void setMaximum(Comparable maxValue)
  {
    maximum = maxValue;
    if (valueClass == null && maxValue != null)
      valueClass = maxValue.getClass();
  }

  /**
   * Returns the maximal value that is allowed by this Formatter.
   *
   * A <code>null</code> value means that there is no restriction.
   *
   * @return the maximal value that is allowed by this Formatter or
   *     <code>null</code> if there is no restriction
   */
  public Comparable getMaximum()
  {
    return maximum;
  }

  /**
   * 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);
  }

  /**
   * Converts a value object into a String. This is done by invoking
   * {@link Format#format(Object)} on the specified <code>Format</code> object.
   * If no format is set, then {@link DefaultFormatter#valueToString(Object)}
   * is called as a fallback.
   *
   * @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 "";
    if (format != null)
      return format.format(value);
    else
      return super.valueToString(value);
  }

  /**
   * Converts a String (from the JFormattedTextField input) to a value.
   * This is achieved by invoking {@link Format#parseObject(String)} on
   * the specified <code>Format</code> object.
   *
   * This implementation differs slightly from {@link DefaultFormatter},
   * it does:
   * <ol>
   * <li>Convert the string to an <code>Object</code> using the
   *   <code>Formatter</code>.</li>
   * <li>If a <code>valueClass</code> has been set, this object is passed to
   *   {@link DefaultFormatter#stringToValue(String)} so that the value
   *   has the correct type. This may or may not work correctly, depending on
   *   the implementation of toString() in the value class and if the class
   *   implements a constructor that takes one String as argument.</li>
   * <li>If no {@link ParseException} has been thrown so far, we check if the
   *   value exceeds either <code>minimum</code> or <code>maximum</code> if
   *   one of those has been specified and throw a <code>ParseException</code>
   *   if it does.</li>
   * <li>Return the value.</li>
   * </ol>
   *
   * If no format has been specified, then
   * {@link DefaultFormatter#stringToValue(String)} is invoked as fallback.
   *
   * @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
  {
    if (format != null)
      {
        Object o = format.parseObject(string);

        // If a value class has been set, call super in order to get
        // the class right. That is what the JDK API docs suggest, so we do
        // it that way.
        if (valueClass != null)
          o = super.stringToValue(o.toString());

        // Check for minimum and maximum bounds
        if (minimum != null && minimum.compareTo(o) > 0)
          throw new ParseException("The value may not be less than the"
                                    + " specified minimum", 0);
        if (maximum != null && maximum.compareTo(o) < 0)
          throw new ParseException("The value may not be greater than the"
                                    + " specified maximum", 0);
        return o;
      }
    else
      return super.stringToValue(string);
  }

  /**
   * Returns the {@link Format.Field} constants that are associated with
   * the specified position in the text.
   *
   * If <code>offset</code> is not a valid location in the input field,
   * an empty array of fields is returned.
   *
   * @param offset the position in the text from which we want to fetch
   *     the fields constants
   *
   * @return the field values associated with the specified position in
   *     the text
   */
  public Format.Field[] getFields(int offset)
  {
    // TODO: don't know if this is correct
    AttributedCharacterIterator aci = format.formatToCharacterIterator
                                         (getFormattedTextField().getValue());
    aci.setIndex(offset);
    Map atts = aci.getAttributes();
    Set keys = atts.keySet();
    Format.Field[] fields = new Format.Field[keys.size()];
    int index = 0;
    for (Iterator i = keys.iterator(); i.hasNext(); index++)
      fields[index] = (Format.Field) i.next();
    return fields;
  }

  /**
   * This creates and returns a clone of this Formatter.
   *
   * @return a clone of this formatter
   *
   * @throws CloneNotSupportedException not thrown here, since cloning is
   *     supported
   */
  public Object clone()
    throws CloneNotSupportedException
  {
    // TODO: it has to be considered, if we should return a deep or shallow
    // clone here. for now we return a shallow clone
    Object clone = super.clone();
    return clone;
  }

  /**
   * Returns the Actions that are supported by this Formatter.
   *
   * @specnote the JDK API docs say here: <cite>If
   *     <code>getSupportsIncrement</code> returns true, this returns two
   *     Actions suitable for incrementing/decrementing the value.</cite>
   *     The questsion is, which method <code>getSupportsIncrement</code>?
   *     There is no such method in the whole API! So we just call
   *     super.getActions here.
   */
  protected Action[] getActions()
  {
    return super.getActions();
  }
}