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'rapiddweller Common' is an open source Java library forked from Databene Commons by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.
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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * 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.
 */

package com.rapiddweller.common.format;

import com.rapiddweller.common.NullSafeComparator;
import com.rapiddweller.common.StringUtil;
import com.rapiddweller.common.converter.ToStringConverter;

import java.text.FieldPosition;
import java.text.Format;
import java.text.ParsePosition;

/**
 * {@link Format} implementation that applies padding for formatting Strings with a fixed width.
 * Created: 07.06.2007 13:23:37
 *
 * @author Volker Bergmann
 */
public class PadFormat extends Format {

  private static final long serialVersionUID = -8263536650454913565L;

  private final String nullString;
  private final Format format;
  private final StringPadder padder;

  /**
   * Instantiates a new Pad format.
   *
   * @param nullString the null string
   * @param length     the length
   * @param alignment  the alignment
   * @param padChar    the pad char
   */
  public PadFormat(String nullString, int length, Alignment alignment, char padChar) {
    this(null, nullString, length, alignment, padChar);
  }

  /**
   * Instantiates a new Pad format.
   *
   * @param format     the format
   * @param nullString the null string
   * @param length     the length
   * @param alignment  the alignment
   * @param padChar    the pad char
   */
  public PadFormat(Format format, String nullString, int length, Alignment alignment, char padChar) {
    assert alignment != null;
    assert padChar != 0;
    this.format = format;
    this.nullString = nullString;
    this.padder = (length > 0 ? new StringPadder(length, alignment, padChar) : null);
  }

  // properties ------------------------------------------------------------------------------------------------------

  /**
   * Gets length.
   *
   * @return the length
   */
  public int getLength() {
    return padder.getLength();
  }

  /**
   * Gets alignment.
   *
   * @return the alignment
   */
  public Alignment getAlignment() {
    return padder.getAlignment();
  }

  /**
   * Gets pad char.
   *
   * @return the pad char
   */
  public char getPadChar() {
    return padder.getPadChar();
  }


  // Format interface implementation ---------------------------------------------------------------------------------

  @Override
  public StringBuffer format(Object object, StringBuffer toAppendTo, FieldPosition pos) {
    String text;
    if (object == null) {
      text = nullString;
    } else if (format != null) {
      text = format.format(object);
    } else {
      text = ToStringConverter.convert(object, nullString);
    }
    if (padder != null) {
      text = padder.convert(text);
    }
    return toAppendTo.append(text);
  }

  @Override
  public Object parseObject(String source, ParsePosition pos) {
    if (source == null) {
      pos.setIndex(1);
      return null;
    }
    String tmp = source.substring(pos.getIndex());
    char padChar = getPadChar();
    switch (getAlignment()) {
      case LEFT:
        tmp = StringUtil.trimRight(tmp, padChar);
        break;
      case RIGHT:
        boolean neg = (padChar == '0' && tmp.length() > 0 && tmp.charAt(0) == '-');
        if (neg) {
          tmp = '-' + StringUtil.trimLeft(tmp.substring(1), padChar);
        } else {
          tmp = StringUtil.trimLeft(tmp, padChar);
        }
        break;
      case CENTER:
        tmp = StringUtil.trim(tmp, padChar);
        break;
      default:
        throw new IllegalArgumentException("Illegal Alignement: " + getAlignment());
    }
    Object result;
    if (format != null) {
      result = format.parseObject(tmp, pos);
    } else {
      result = tmp;
      if (StringUtil.isEmpty(source)) {
        pos.setIndex(1);
      } else {
        pos.setIndex(source.length());
      }
    }
    return result;
  }


  // java.lang.Object overrides --------------------------------------------------------------------------------------

  @Override
  public int hashCode() {
    return padder.hashCode() * 31 + format.hashCode();
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj == null || getClass() != obj.getClass()) {
      return false;
    }
    final PadFormat that = (PadFormat) obj;
    return (NullSafeComparator.equals(this.padder, that.padder) &&
        NullSafeComparator.equals(this.format, that.format));
  }

  @Override
  public String toString() {
    return padder.toString();
  }

}