using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ST.Library.UI.STTextBox

{

public class TextHistory : ITextHistory

{

private int m_nIndex;

private int m_nCount;

private int m_nMax;

private TextHistoryRecord[][] m_arr;

public TextHistory(int nCount) {

m_nMax = nCount;

m_arr = new TextHistoryRecord[nCount][];

}

public void SetHistory(TextHistoryRecord[] histories) {

if (m_nIndex == m_nMax) {

for (int i = 1; i < m_arr.Length; i++) {

m_arr[i - 1] = m_arr[i];

}

m_nIndex--;

}

m_arr[m_nIndex++] = histories;

m_nCount = m_nIndex;

}

public TextHistoryRecord[] GetUndo() {

if (m_nIndex == 0) { //not have history

return null;

}

return m_arr[--m_nIndex];

}

public TextHistoryRecord[] GetRedo() {

if (m_nIndex == m_nCount) {

return null;

}

return m_arr[m_nIndex++];

}

public void Clear() {

m_nIndex = m_nCount = 0;

}

}

}