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/*
* Copyright 2013 The Netty Project
*
* The Netty Project 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.glowroot.shaded.netty.util.internal;
import java.util.Arrays;
public final class AppendableCharSequence implements CharSequence, Appendable {
private char[] chars;
private int pos;
public AppendableCharSequence(int length) {
if (length < 1) {
throw new IllegalArgumentException("length: " + length + " (length: >= 1)");
}
chars = new char[length];
}
private AppendableCharSequence(char[] chars) {
this.chars = chars;
pos = chars.length;
}
@Override
public int length() {
return pos;
}
@Override
public char charAt(int index) {
if (index > pos) {
throw new IndexOutOfBoundsException();
}
return chars[index];
}
@Override
public AppendableCharSequence subSequence(int start, int end) {
return new AppendableCharSequence(Arrays.copyOfRange(chars, start, end));
}
@Override
public AppendableCharSequence append(char c) {
if (pos == chars.length) {
char[] old = chars;
// double it
int len = old.length << 1;
if (len < 0) {
throw new IllegalStateException();
}
chars = new char[len];
System.arraycopy(old, 0, chars, 0, old.length);
}
chars[pos++] = c;
return this;
}
@Override
public AppendableCharSequence append(CharSequence csq) {
return append(csq, 0, csq.length());
}
@Override
public AppendableCharSequence append(CharSequence csq, int start, int end) {
if (csq.length() < end) {
throw new IndexOutOfBoundsException();
}
int length = end - start;
if (length > chars.length - pos) {
chars = expand(chars, pos + length, pos);
}
if (csq instanceof AppendableCharSequence) {
// Optimize append operations via array copy
AppendableCharSequence seq = (AppendableCharSequence) csq;
char[] src = seq.chars;
System.arraycopy(src, start, chars, pos, length);
pos += length;
return this;
}
for (int i = start; i < end; i++) {
chars[pos++] = csq.charAt(i);
}
return this;
}
/**
* Reset the {@link AppendableCharSequence}. Be aware this will only reset the current internal position and not
* shrink the internal char array.
*/
public void reset() {
pos = 0;
}
@Override
public String toString() {
return new String(chars, 0, pos);
}
/**
* Create a new {@link String} from the given start to end.
*/
public String substring(int start, int end) {
int length = end - start;
if (start > pos || length > pos) {
throw new IndexOutOfBoundsException();
}
return new String(chars, start, length);
}
private static char[] expand(char[] array, int neededSpace, int size) {
int newCapacity = array.length;
do {
// double capacity until it is big enough
newCapacity <<= 1;
if (newCapacity < 0) {
throw new IllegalStateException();
}
} while (neededSpace > newCapacity);
char[] newArray = new char[newCapacity];
System.arraycopy(array, 0, newArray, 0, size);
return newArray;
}
}