/*******************************************************************************
* Copyright (c) 2000, 2009 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.jdt.internal.core.util;
import org.eclipse.jdt.internal.compiler.util.Util;
/**
* The <code>CharArrayBuffer</code> is intended as a lightweight partial implementation
* of the StringBuffer class, but using <code>char[]'s</code> instead of Strings.
*
* <p>The <code>CharArrayBuffer</code> maintains a list of <code>char[]'s</code>
* which don't get appended until the user asks for them. The following
* code illustrates how to use the class.
*
* <code>
* CharArrayBuffer buffer = new CharArrayBuffer(myCharArray);
* buffer.append(moreBytes, 0, someLength);
* myCharArray = buffer.getContents();
* </code>
*
* <p>NOTE: This class is not Thread safe!
*/
public class CharArrayBuffer {
/**
* This is the buffer of char arrays which must be appended together
* during the getContents method.
*/
protected char[][] buffer;
/**
* The default buffer size.
*/
public static final int DEFAULT_BUFFER_SIZE = 10;
/**
* The end of the buffer
*/
protected int end;
/**
* The current size of the buffer.
*/
protected int size;
/**
* A buffer of ranges which is maintained along with
* the buffer. Ranges are of the form {start, length}.
* Enables append(char[] array, int start, int end).
*/
protected int[][] ranges;
/**
* Creates a <code>CharArrayBuffer</code> with the default buffer size (10).
*/
public CharArrayBuffer() {
this(null, DEFAULT_BUFFER_SIZE);
}
/**
* Creates a <code>CharArrayBuffer</code> with the default buffer size,
* and sets the first element in the buffer to be the given char[].
*
* @param first - the first element to be placed in the buffer, ignored if null
*/
public CharArrayBuffer(char[] first) {
this(first, DEFAULT_BUFFER_SIZE);
}
/**
* Creates a <code>CharArrayBuffer</code> with the given buffer size,
* and sets the first element in the buffer to be the given char array.
*
* @param first - the first element of the buffer, ignored if null.
* @param size - the buffer size, if less than 1, set to the DEFAULT_BUFFER_SIZE.
*/
public CharArrayBuffer(char[] first, int size) {
this.size = (size > 0) ? size : DEFAULT_BUFFER_SIZE;
this.buffer = new char[this.size][];
this.ranges = new int[this.size][];
this.end = 0;
if (first != null)
append(first, 0, first.length);
}
/**
* Creates a <code>CharArrayBuffer</code> with the given buffer size.
*
* @param size - the size of the buffer.
*/
public CharArrayBuffer(int size) {
this(null, size);
}
/**
* Appends the entire given char array. Given for convenience.
*
* @param src - a char array which is appended to the end of the buffer.
*/
public CharArrayBuffer append(char[] src) {
if (src != null)
append(src, 0, src.length);
return this;
}
/**
* Appends a sub array of the given array to the buffer.
*
* @param src - the next array of characters to be appended to the buffer, ignored if null
* @param start - the start index in the src array.
* @param length - the number of characters from start to be appended
*
* @throws ArrayIndexOutOfBoundsException - if arguments specify an array index out of bounds.
*/
public CharArrayBuffer append(char[] src, int start, int length) {
if (start < 0) throw new ArrayIndexOutOfBoundsException();
if (length < 0) throw new ArrayIndexOutOfBoundsException();
if (src != null) {
int srcLength = src.length;
if (start > srcLength) throw new ArrayIndexOutOfBoundsException();
if (length + start > srcLength) throw new ArrayIndexOutOfBoundsException();
/** do length check here to allow exceptions to be thrown */
if (length > 0) {
if (this.end == this.size) {
int size2 = this.size * 2;
System.arraycopy(this.buffer, 0, (this.buffer = new char[size2][]), 0, this.size);
System.arraycopy(this.ranges, 0, (this.ranges = new int[size2][]), 0, this.size);
this.size *= 2;
}
this.buffer[this.end] = src;
this.ranges[this.end] = new int[] {start, length};
this.end++;
}
}
return this;
}
/**
* Appends the given char. Given for convenience.
*
* @param c - a char which is appended to the end of the buffer.
*/
public CharArrayBuffer append(char c) {
append(new char[] {c}, 0, 1);
return this;
}
/**
* Appends the given String to the buffer. Given for convenience, use
* #append(char[]) if possible
*
* @param src - a char array which is appended to the end of the buffer.
*/
public CharArrayBuffer append(String src) {
if (src != null)
append(src.toCharArray(), 0, src.length());
return this;
}
/**
* Returns the entire contents of the buffer as one
* char[] or null if nothing has been put in the buffer.
*/
public char[] getContents() {
if (this.end == 0)
return null;
// determine the length of the array
int length = 0;
for (int i = 0; i < this.end; i++)
length += this.ranges[i][1];
if (length > 0) {
char[] result = new char[length];
int current = 0;
// copy the results
for(int i = 0; i < this.end; i++) {
int[] range = this.ranges[i];
int length2 = range[1];
System.arraycopy(this.buffer[i], range[0], result, current, length2);
current += length2;
}
return result;
}
return null;
}
/**
* Returns the contents of the buffer as a String, or
* an empty string if the buffer is empty.
*/
public String toString() {
char[] contents = getContents();
return (contents != null) ? new String(contents) : Util.EMPTY_STRING;
}
}