org.apache.wicket.util.string.PrependingStringBuffer Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.wicket.util.string;
/**
* This is a prepending stringbuffer optimized for constantly prepending strings to the front of the
* buffer.
*
* @author jcompagner
*/
public class PrependingStringBuffer
{
private int size;
private int position;
private char[] buffer;
/**
* Default constructor, the internal initial buffer size will be 16
*/
public PrependingStringBuffer()
{
this(16);
}
/**
* Constructs this PrependingStringBuffer with the given buffer size.
*
* @param size
* The initial size of the buffer.
*/
public PrependingStringBuffer(final int size)
{
buffer = new char[size];
position = size;
this.size = 0;
}
/**
* Constructs and direct inserts the given string. The buffer size will be string.length+16
*
* @param start
* The string that is directly inserted.
*/
public PrependingStringBuffer(final String start)
{
this(start.length() + 16);
prepend(start);
}
/**
* Prepends one char to this PrependingStringBuffer
*
* @param ch
* The char that will be prepended
* @return this
*/
public PrependingStringBuffer prepend(final char ch)
{
int len = 1;
if (position < len)
{
expandCapacity(size + len);
}
position -= len;
buffer[position] = ch;
size += len;
return this;
}
/**
* Prepends the string to this PrependingStringBuffer
*
* @param str
* The string that will be prepended
* @return this
*/
public PrependingStringBuffer prepend(final String str)
{
int len = str.length();
if (position < len)
{
expandCapacity(size + len);
}
str.getChars(0, len, buffer, position - len);
position -= len;
size += len;
return this;
}
private void expandCapacity(final int minimumCapacity)
{
int newCapacity = (buffer.length + 1) * 2;
if (newCapacity < 0)
{
newCapacity = Integer.MAX_VALUE;
}
else if (minimumCapacity > newCapacity)
{
newCapacity = minimumCapacity;
}
char newValue[] = new char[newCapacity];
System.arraycopy(buffer, position, newValue, newCapacity - size, size);
buffer = newValue;
position = newCapacity - size;
}
/**
* Returns the size of this PrependingStringBuffer
*
* @return The size
*/
public int length()
{
return size;
}
/**
* @see java.lang.Object#toString()
*/
@Override
public String toString()
{
return new String(buffer, position, size);
}
@Override
public boolean equals(final Object obj)
{
if (obj == this)
{
return true;
}
else if (obj == null)
{
return false;
}
else
{
return toString().equals(obj.toString());
}
}
@Override
public int hashCode()
{
return toString().hashCode();
}
}