/* SizeSequence.java --
   Copyright (C) 2002, 2006, Free Software Foundation, Inc.

This file is part of GNU Classpath.

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

import java.util.Arrays;

/**
 * A sequence of values that represent the dimensions (widths or heights) of 
 * some collection of items (for example, the widths of the columns in a table).
 * 
 * @author	Andrew Selkirk
 */
public class SizeSequence
{
  // TODO: Sun's API specification for this class contains an implementation
  // note regarding the encoding for the element sizes.  We currently use the
  // simple size encoding but we should look at improving this.
  
  /** Storage for the element sizes. */
  private int[] sizes;

  /**
   * Creates a new empty <code>SizeSequence</code> instance.
   */
  public SizeSequence()
  {
    sizes = new int[0];
  }

  /**
   * Creates a new <code>SizeSequence</code> instance with the specified number 
   * of elements, each having a size of 0.
   * 
   * @param numEntries  the number of elements.
   */
  public SizeSequence(int numEntries)
  {
    this(numEntries, 0);
  }

  /**
   * Creates a new <code>SizeSequence</code> instance with the specified number
   * of elements all having the same size (<code>value</code>).
   * 
   * @param numEntries  the number of elements.
   * @param value  the value for each element.
   */
  public SizeSequence(int numEntries, int value)
  {
    sizes = new int[numEntries];
    Arrays.fill(sizes, value);
  }

  /**
   * Creates a new <code>SizeSequence</code> instance using the specified 
   * element sizes.
   * 
   * @param sizes  the element sizes (<code>null</code> not permitted).
   */
  public SizeSequence(int[] sizes)
  {
    this.sizes = (int[]) sizes.clone();
  }

  /**
   * Sets the size of the element at the specified index.
   * 
   * @param index  the index.
   * @param size  the size.
   */
  public void setSize(int index, int size)
  {
    if (index >= 0 && index < sizes.length)
      sizes[index] = size;
  }

  /**
   * Returns the index of the element that contains the specified position.
   * 
   * @param position  the position.
   * 
   * @return The index of the element that contains the specified position.
   */
  public int getIndex(int position)
  {
    int i = 0;
    int runningTotal = 0;  
    while (i < sizes.length && position >= runningTotal + sizes[i]) 
      {
        runningTotal += sizes[i];
        i++;
      }
    return i;
  }

  /**
   * Returns the size of the specified element.
   * 
   * @param index  the element index.
   * 
   * @return The size of the specified element.
   */
  public int getSize(int index)
  {
    return sizes[index];
  }

  /**
   * Sets the sizes for the elements in the sequence.
   * 
   * @param sizes  the element sizes (<code>null</code> not permitted).
   */
  public void setSizes(int[] sizes)
  {
    this.sizes = (int[]) sizes.clone();
  }

  /**
   * Returns an array containing the sizes for all the elements in the sequence.
   * 
   * @return The element sizes.
   */
  public int[] getSizes()
  {
    return (int[]) sizes.clone();
  }

  /**
   * Returns the position of the specified element.
   * 
   * @param index  the element index.
   * 
   * @return The position.
   */
  public int getPosition(int index)
  {
    int position;
    int loop;
    position = 0;
    for (loop = 0; loop < index; loop++)
      position += sizes[loop];
    return position;

  }

  /**
   * Inserts new entries into the sequence at the <code>start</code> position.
   * There are <code>length</code> new entries each having the specified
   * <code>value</code>.
   * 
   * @param start  the start element.
   * @param length  the number of elements to insert.
   * @param value  the size for each of the new elements.
   */
  public void insertEntries(int start, int length, int value)
  {
    int[] newSizes = new int[sizes.length + length];
    System.arraycopy(sizes, 0, newSizes, 0, start);
    for (int i = start; i < start + length; i++)
      newSizes[i] = value;
    System.arraycopy(sizes, start, newSizes, start + length, 
                     sizes.length - start);
    sizes = newSizes;
  }

  /**
   * Removes the element(s) at index <code>start</code> (the number of elements
   * removed is <code>length</code>).
   * 
   * @param start  the index of the first element to remove.
   * @param length  the number of elements to remove.
   */
  public void removeEntries(int start, int length)
  {
    // Sanity check.
    if ((start + length) > sizes.length)
      throw new IllegalArgumentException("Specified start/length that "
                                         + "is greater than available sizes");

    int[] newSizes = new int[sizes.length - length];
    System.arraycopy(sizes, 0, newSizes, 0, start);
    System.arraycopy(sizes, start + length, newSizes, start, 
                     sizes.length - start - length);
    sizes = newSizes;
  }
}