CharChunk.java
/*
* 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.tomcat.util.buf;
import java.io.IOException;
/**
* Utilities to manipulate char chunks. While String is the easiest way to manipulate chars ( search, substrings, etc),
* it is known to not be the most efficient solution - Strings are designed as immutable and secure objects.
*
* @author dac@sun.com
* @author James Todd [gonzo@sun.com]
* @author Costin Manolache
* @author Remy Maucherat
*/
public final class CharChunk extends AbstractChunk implements CharSequence {
private static final long serialVersionUID = 1L;
/**
* Input interface, used when the buffer is empty.
*/
public interface CharInputChannel {
/**
* Read new characters.
*
* @return The number of characters read
*
* @throws IOException If an I/O error occurs during reading
*/
int realReadChars() throws IOException;
}
/**
* When we need more space we'll either grow the buffer ( up to the limit ) or send it to a channel.
*/
public interface CharOutputChannel {
/**
* Send the bytes ( usually the internal conversion buffer ). Expect 8k output if the buffer is full.
*
* @param buf characters that will be written
* @param off offset in the characters array
* @param len length that will be written
*
* @throws IOException If an I/O occurs while writing the characters
*/
void realWriteChars(char buf[], int off, int len) throws IOException;
}
// --------------------
// char[]
private char[] buff;
// transient as serialization is primarily for values via, e.g. JMX
private transient CharInputChannel in = null;
private transient CharOutputChannel out = null;
/**
* Creates a new, uninitialized CharChunk object.
*/
public CharChunk() {
}
public CharChunk(int initial) {
allocate(initial, -1);
}
// --------------------
@Override
public Object clone() throws CloneNotSupportedException {
return super.clone();
}
// -------------------- Setup --------------------
public void allocate(int initial, int limit) {
if (buff == null || buff.length < initial) {
buff = new char[initial];
}
setLimit(limit);
start = 0;
end = 0;
isSet = true;
hasHashCode = false;
}
/**
* Sets the buffer to the specified subarray of characters.
*
* @param c the characters
* @param off the start offset of the characters
* @param len the length of the characters
*/
public void setChars(char[] c, int off, int len) {
buff = c;
start = off;
end = start + len;
isSet = true;
hasHashCode = false;
}
/**
* @return the buffer.
*/
public char[] getChars() {
return getBuffer();
}
/**
* @return the buffer.
*/
public char[] getBuffer() {
return buff;
}
/**
* When the buffer is empty, read the data from the input channel.
*
* @param in The input channel
*/
public void setCharInputChannel(CharInputChannel in) {
this.in = in;
}
/**
* When the buffer is full, write the data to the output channel. Also used when large amount of data is appended.
* If not set, the buffer will grow to the limit.
*
* @param out The output channel
*/
public void setCharOutputChannel(CharOutputChannel out) {
this.out = out;
}
// -------------------- Adding data to the buffer --------------------
public void append(char c) throws IOException {
makeSpace(1);
int limit = getLimitInternal();
// couldn't make space
if (end >= limit) {
flushBuffer();
}
buff[end++] = c;
}
public void append(CharChunk src) throws IOException {
append(src.getBuffer(), src.getOffset(), src.getLength());
}
/**
* Add data to the buffer.
*
* @param src Char array
* @param off Offset
* @param len Length
*
* @throws IOException Writing overflow data to the output channel failed
*/
public void append(char src[], int off, int len) throws IOException {
// will grow, up to limit
makeSpace(len);
int limit = getLimitInternal();
// Optimize on a common case.
// If the buffer is empty and the source is going to fill up all the
// space in buffer, may as well write it directly to the output,
// and avoid an extra copy
if (len == limit && end == start && out != null) {
out.realWriteChars(src, off, len);
return;
}
// if we are below the limit
if (len <= limit - end) {
System.arraycopy(src, off, buff, end, len);
end += len;
return;
}
// Need more space than we can afford, need to flush buffer.
// The buffer is already at (or bigger than) limit.
// Optimization:
// If len-avail < length (i.e. after we fill the buffer with what we
// can, the remaining will fit in the buffer) we'll just copy the first
// part, flush, then copy the second part - 1 write and still have some
// space for more. We'll still have 2 writes, but we write more on the first.
if (len + end < 2 * limit) {
/*
* If the request length exceeds the size of the output buffer, flush the output buffer and then write the
* data directly. We can't avoid 2 writes, but we can write more on the second
*/
int avail = limit - end;
System.arraycopy(src, off, buff, end, avail);
end += avail;
flushBuffer();
System.arraycopy(src, off + avail, buff, end, len - avail);
end += len - avail;
} else { // len > buf.length + avail
// long write - flush the buffer and write the rest
// directly from source
flushBuffer();
out.realWriteChars(src, off, len);
}
}
/**
* Append a string to the buffer.
*
* @param s The string
*
* @throws IOException Writing overflow data to the output channel failed
*/
public void append(String s) throws IOException {
append(s, 0, s.length());
}
/**
* Append a string to the buffer.
*
* @param s The string
* @param off Offset
* @param len Length
*
* @throws IOException Writing overflow data to the output channel failed
*/
public void append(String s, int off, int len) throws IOException {
if (s == null) {
return;
}
// will grow, up to limit
makeSpace(len);
int limit = getLimitInternal();
int sOff = off;
int sEnd = off + len;
while (sOff < sEnd) {
int d = min(limit - end, sEnd - sOff);
s.getChars(sOff, sOff + d, buff, end);
sOff += d;
end += d;
if (end >= limit) {
flushBuffer();
}
}
}
// -------------------- Removing data from the buffer --------------------
public int subtract() throws IOException {
if (checkEof()) {
return -1;
}
return buff[start++];
}
public int subtract(char dest[], int off, int len) throws IOException {
if (checkEof()) {
return -1;
}
int n = len;
if (len > getLength()) {
n = getLength();
}
System.arraycopy(buff, start, dest, off, n);
start += n;
return n;
}
private boolean checkEof() throws IOException {
if ((end - start) == 0) {
if (in == null) {
return true;
}
int n = in.realReadChars();
if (n < 0) {
return true;
}
}
return false;
}
/**
* Send the buffer to the sink. Called by append() when the limit is reached. You can also call it explicitly to
* force the data to be written.
*
* @throws IOException Writing overflow data to the output channel failed
*/
public void flushBuffer() throws IOException {
// assert out!=null
if (out == null) {
throw new IOException(
sm.getString("chunk.overflow", Integer.valueOf(getLimit()), Integer.valueOf(buff.length)));
}
out.realWriteChars(buff, start, end - start);
end = start;
}
/**
* Make space for len chars. If len is small, allocate a reserve space too. Never grow bigger than the limit or
* {@link AbstractChunk#ARRAY_MAX_SIZE}.
*
* @param count The size
*/
public void makeSpace(int count) {
char[] tmp = null;
int limit = getLimitInternal();
long newSize;
long desiredSize = end + count;
// Can't grow above the limit
if (desiredSize > limit) {
desiredSize = limit;
}
if (buff == null) {
if (desiredSize < 256) {
desiredSize = 256; // take a minimum
}
buff = new char[(int) desiredSize];
}
// limit < buf.length (the buffer is already big)
// or we already have space
if (desiredSize <= buff.length) {
return;
}
// grow in larger chunks
if (desiredSize < 2L * buff.length) {
newSize = buff.length * 2L;
} else {
newSize = buff.length * 2L + count;
}
if (newSize > limit) {
newSize = limit;
}
tmp = new char[(int) newSize];
// Some calling code assumes buffer will not be compacted
System.arraycopy(buff, 0, tmp, 0, end);
buff = tmp;
tmp = null;
}
// -------------------- Conversion and getters --------------------
@Override
public String toString() {
if (isNull()) {
return null;
} else if (end - start == 0) {
return "";
}
return StringCache.toString(this);
}
public String toStringInternal() {
return new String(buff, start, end - start);
}
// -------------------- equals --------------------
@Override
public boolean equals(Object obj) {
if (obj instanceof CharChunk) {
return equals((CharChunk) obj);
}
return false;
}
/**
* Compares the message bytes to the specified String object.
*
* @param s the String to compare
*
* @return <code>true</code> if the comparison succeeded, <code>false</code> otherwise
*/
public boolean equals(String s) {
char[] c = buff;
int len = end - start;
if (c == null || len != s.length()) {
return false;
}
int off = start;
for (int i = 0; i < len; i++) {
if (c[off++] != s.charAt(i)) {
return false;
}
}
return true;
}
/**
* Compares the message bytes to the specified String object.
*
* @param s the String to compare
*
* @return <code>true</code> if the comparison succeeded, <code>false</code> otherwise
*/
public boolean equalsIgnoreCase(String s) {
char[] c = buff;
int len = end - start;
if (c == null || len != s.length()) {
return false;
}
int off = start;
for (int i = 0; i < len; i++) {
if (Ascii.toLower(c[off++]) != Ascii.toLower(s.charAt(i))) {
return false;
}
}
return true;
}
public boolean equals(CharChunk cc) {
return equals(cc.getChars(), cc.getOffset(), cc.getLength());
}
public boolean equals(char b2[], int off2, int len2) {
char b1[] = buff;
if (b1 == null && b2 == null) {
return true;
}
int len = end - start;
if (len != len2 || b1 == null || b2 == null) {
return false;
}
int off1 = start;
while (len-- > 0) {
if (b1[off1++] != b2[off2++]) {
return false;
}
}
return true;
}
/**
* @return <code>true</code> if the message bytes starts with the specified string.
*
* @param s The string
*/
public boolean startsWith(String s) {
char[] c = buff;
int len = s.length();
if (c == null || len > end - start) {
return false;
}
int off = start;
for (int i = 0; i < len; i++) {
if (c[off++] != s.charAt(i)) {
return false;
}
}
return true;
}
/**
* Returns true if the buffer starts with the specified string.
*
* @param s the string
* @param pos The position
*
* @return <code>true</code> if the start matches
*/
public boolean startsWithIgnoreCase(String s, int pos) {
char[] c = buff;
int len = s.length();
if (c == null || len + pos > end - start) {
return false;
}
int off = start + pos;
for (int i = 0; i < len; i++) {
if (Ascii.toLower(c[off++]) != Ascii.toLower(s.charAt(i))) {
return false;
}
}
return true;
}
/**
* @return <code>true</code> if the message bytes end with the specified string.
*
* @param s The string
*/
public boolean endsWith(String s) {
char[] c = buff;
int len = s.length();
if (c == null || len > end - start) {
return false;
}
int off = end - len;
for (int i = 0; i < len; i++) {
if (c[off++] != s.charAt(i)) {
return false;
}
}
return true;
}
@Override
protected int getBufferElement(int index) {
return buff[index];
}
public int indexOf(char c) {
return indexOf(c, start);
}
/**
* Returns the first instance of the given character in this CharChunk starting at the specified char. If the
* character is not found, -1 is returned. <br>
*
* @param c The character
* @param starting The start position
*
* @return The position of the first instance of the character or -1 if the character is not found.
*/
public int indexOf(char c, int starting) {
int ret = indexOf(buff, start + starting, end, c);
return (ret >= start) ? ret - start : -1;
}
/**
* Returns the first instance of the given character in the given char array between the specified start and end.
* <br>
*
* @param chars The array to search
* @param start The point to start searching from in the array
* @param end The point to stop searching in the array
* @param s The character to search for
*
* @return The position of the first instance of the character or -1 if the character is not found.
*/
public static int indexOf(char chars[], int start, int end, char s) {
int offset = start;
while (offset < end) {
char c = chars[offset];
if (c == s) {
return offset;
}
offset++;
}
return -1;
}
// -------------------- utils
private int min(int a, int b) {
if (a < b) {
return a;
}
return b;
}
// Char sequence impl
@Override
public char charAt(int index) {
return buff[index + start];
}
@Override
public CharSequence subSequence(int start, int end) {
try {
CharChunk result = (CharChunk) this.clone();
result.setOffset(this.start + start);
result.setEnd(this.start + end);
return result;
} catch (CloneNotSupportedException e) {
// Cannot happen
return null;
}
}
@Override
public int length() {
return end - start;
}
}