/**
* Copyright 2005 The Apache Software Foundation
*
* Licensed 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.hadoop.io;
import java.io.IOException;
import java.io.DataInput;
import java.io.DataOutput;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CodingErrorAction;
import java.nio.charset.MalformedInputException;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/** This class stores text using standard UTF8 encoding. It provides methods
* to serialize, deserialize, and compare texts at byte level. The type of
* length is integer and is serialized using zero-compressed format. <p>In
* addition, it provides methods for string traversal without converting the
* byte array to a string. <p>Also includes utilities for
* serializing/deserialing a string, coding/decoding a string, checking if a
* byte array contains valid UTF8 code, calculating the length of an encoded
* string.
*/
public class Text implements WritableComparable {
private static final Log LOG= LogFactory.getLog("org.apache.hadoop.io.Text");
private static final CharsetDecoder DECODER =
Charset.forName("UTF-8").newDecoder().
onMalformedInput(CodingErrorAction.REPORT).
onUnmappableCharacter(CodingErrorAction.REPORT);
private static final CharsetEncoder ENCODER =
Charset.forName("UTF-8").newEncoder().
onMalformedInput(CodingErrorAction.REPORT).
onUnmappableCharacter(CodingErrorAction.REPORT);
private static final byte [] EMPTY_BYTES = new byte[0];
private byte[] bytes;
private int length;
public Text() {
bytes = EMPTY_BYTES;
}
/** Construct from a string.
*/
public Text(String string) {
set(string);
}
/** Construct from another text. */
public Text(Text utf8) {
set(utf8);
}
/** Construct from a byte array.
*/
public Text(byte[] utf8) {
set(utf8);
}
/** Retuns the raw bytes. */
public byte[] getBytes() {
return bytes;
}
/** Returns the number of bytes in the byte array */
public int getLength() {
return length;
}
/**
* Returns the Unicode Scalar Value (32-bit integer value)
* for the character at <code>position</code>. Note that this
* method avoids using the converter or doing String instatiation
* @returns the Unicode scalar value at position or -1
* if the position is invalid or points to a
* trailing byte
*/
public int charAt(int position) {
if (position > this.length) return -1; // too long
if (position < 0) return -1; // duh.
ByteBuffer bb = (ByteBuffer)ByteBuffer.wrap(bytes).position(position);
return bytesToCodePoint(bb.slice());
}
public int find(String what) {
return find(what, 0);
}
/**
* Finds any occurence of <code>what</code> in the backing
* buffer, starting as position <code>start</code>. The starting
* position is measured in bytes and the return value is in
* terms of byte position in the buffer. The backing buffer is
* not converted to a string for this operation.
* @return byte position of the first occurence of the search
* string in the UTF-8 buffer or -1 if not found
*/
public int find(String what, int start) {
try {
ByteBuffer src = ByteBuffer.wrap(this.bytes);
ByteBuffer tgt = encode(what);
byte b = tgt.get();
src.position(start);
while (src.hasRemaining()) {
if (b == src.get()) { // matching first byte
src.mark(); // save position in loop
tgt.mark(); // save position in target
boolean found = true;
int pos = src.position()-1;
while (tgt.hasRemaining()) {
if (!src.hasRemaining()) { // src expired first
tgt.reset();
src.reset();
found = false;
break;
}
if (!(tgt.get() == src.get())) {
tgt.reset();
src.reset();
found = false;
break; // no match
}
}
if (found) return pos;
}
}
return -1; // not found
} catch (CharacterCodingException e) {
// can't get here
e.printStackTrace();
return -1;
}
}
/** Set to contain the contents of a string.
*/
public void set(String string) {
try {
ByteBuffer bb = encode(string, true);
bytes = bb.array();
length = bb.limit();
}catch(CharacterCodingException e) {
throw new RuntimeException("Should not have happened " + e.toString());
}
}
/** Set to a utf8 byte array
*/
public void set(byte[] utf8) {
set(utf8, 0, utf8.length);
}
/** copy a text. */
public void set(Text other) {
set(other.bytes, 0, other.length);
}
/**
* Set the Text to range of bytes
* @param utf8 the data to copy from
* @param start the first position of the new string
* @param len the number of bytes of the new string
*/
public void set(byte[] utf8, int start, int len) {
setCapacity(len);
System.arraycopy(utf8, start, bytes, 0, len);
this.length = len;
}
/*
* Sets the capacity of this Text object to <em>at least</em>
* <code>len</code> bytes. If the current buffer is longer,
* then the capacity and existing content of the buffer are
* unchanged. If <code>len</code> is larger
* than the current capacity, the Text object's capacity is
* increased to match. The existing contents of the buffer
* (if any) are deleted.
*/
private void setCapacity( int len ) {
if (bytes == null || bytes.length < len)
bytes = new byte[len];
}
/**
* Convert text back to string
* @see java.lang.Object#toString()
*/
public String toString() {
try {
return decode(bytes, 0, length);
} catch (CharacterCodingException e) {
return null;
}
}
/** deserialize
*/
public void readFields(DataInput in) throws IOException {
length = WritableUtils.readVInt(in);
setCapacity(length);
in.readFully(bytes, 0, length);
}
/** Skips over one Text in the input. */
public static void skip(DataInput in) throws IOException {
int length = WritableUtils.readVInt(in);
in.skipBytes(length);
}
/** serialize
* write this object to out
* length uses zero-compressed encoding
* @see Writable#write(DataOutput)
*/
public void write(DataOutput out) throws IOException {
WritableUtils.writeVInt(out, length);
out.write(bytes, 0, length);
}
/** Compare two Texts bytewise using standard UTF8 ordering. */
public int compareTo(Object o) {
Text that = (Text)o;
if(this == that)
return 0;
else
return WritableComparator.compareBytes(bytes, 0, length,
that.bytes, 0, that.length);
}
/** Returns true iff <code>o</code> is a Text with the same contents. */
public boolean equals(Object o) {
if (!(o instanceof Text))
return false;
Text that = (Text)o;
if (this == that)
return true;
else if (this.length != that.length)
return false;
else
return WritableComparator.compareBytes(bytes, 0, length,
that.bytes, 0, that.length) == 0;
}
/** hash function */
public int hashCode() {
return WritableComparator.hashBytes(bytes, length);
}
/** A WritableComparator optimized for Text keys. */
public static class Comparator extends WritableComparator {
public Comparator() {
super(Text.class);
}
public int compare(byte[] b1, int s1, int l1,
byte[] b2, int s2, int l2) {
try {
int n1 = readVInt(b1, s1);
int n2 = readVInt(b2, s2);
return compareBytes(b1, s1+WritableUtils.getVIntSize(n1), n1,
b2, s2+WritableUtils.getVIntSize(n2), n2);
}catch(IOException e) {
LOG.warn(e);
throw new RuntimeException(e);
}
}
}
static {
// register this comparator
WritableComparator.define(Text.class, new Comparator());
}
/// STATIC UTILITIES FROM HERE DOWN
/**
* Converts the provided byte array to a String using the
* UTF-8 encoding. If the input is malformed,
* replace by a default value.
*/
public static String decode(byte[] utf8) throws CharacterCodingException {
return decode(ByteBuffer.wrap(utf8), true);
}
public static String decode(byte[] utf8, int start, int length)
throws CharacterCodingException {
return decode(ByteBuffer.wrap(utf8, start, length), true);
}
/**
* Converts the provided byte array to a String using the
* UTF-8 encoding. If <code>replace</code> is true, then
* malformed input is replaced with the
* substitution character, which is U+FFFD. Otherwise the
* method throws a MalformedInputException.
*/
public static String decode(byte[] utf8, int start, int length, boolean replace)
throws CharacterCodingException {
return decode(ByteBuffer.wrap(utf8, start, length), replace);
}
private static String decode(ByteBuffer utf8, boolean replace)
throws CharacterCodingException {
synchronized(DECODER) {
if (replace) {
DECODER.onMalformedInput(
java.nio.charset.CodingErrorAction.REPLACE);
DECODER.onUnmappableCharacter(CodingErrorAction.REPLACE);
}
String str = DECODER.decode(utf8).toString();
// set decoder back to its default value: REPORT
if (replace) {
DECODER.onMalformedInput(CodingErrorAction.REPORT);
DECODER.onUnmappableCharacter(CodingErrorAction.REPORT);
}
return str;
}
}
/**
* Converts the provided String to bytes using the
* UTF-8 encoding. If the input is malformed,
* invalid chars are replaced by a default value.
* @return ByteBuffer: bytes stores at ByteBuffer.array()
* and length is ByteBuffer.limit()
*/
public static ByteBuffer encode(String string)
throws CharacterCodingException {
return encode(string, true);
}
/**
* Converts the provided String to bytes using the
* UTF-8 encoding. If <code>replace</code> is true, then
* malformed input is replaced with the
* substitution character, which is U+FFFD. Otherwise the
* method throws a MalformedInputException.
* @return ByteBuffer: bytes stores at ByteBuffer.array()
* and length is ByteBuffer.limit()
*/
public static ByteBuffer encode(String string, boolean replace)
throws CharacterCodingException {
synchronized(ENCODER) {
if (replace) {
ENCODER.onMalformedInput(CodingErrorAction.REPLACE);
ENCODER.onUnmappableCharacter(CodingErrorAction.REPLACE);
}
ByteBuffer bytes=ENCODER.encode(CharBuffer.wrap(string.toCharArray()));
if (replace) {
ENCODER.onMalformedInput(CodingErrorAction.REPORT);
ENCODER.onUnmappableCharacter(CodingErrorAction.REPORT);
}
return bytes;
}
}
/** Read a UTF8 encoded string from in
*/
public static String readString(DataInput in) throws IOException {
int length = WritableUtils.readVInt(in);
byte [] bytes = new byte[length];
in.readFully(bytes, 0, length);
return decode(bytes);
}
/** Write a UTF8 encoded string to out
*/
public static int writeString(DataOutput out, String s) throws IOException {
ByteBuffer bytes = encode(s);
int length = bytes.limit();
WritableUtils.writeVInt(out, length);
out.write(bytes.array(), 0, length);
return length;
}
////// states for validateUTF8
private static final int LEAD_BYTE = 0;
private static final int TRAIL_BYTE_1 = 1;
private static final int TRAIL_BYTE = 2;
/**
* Check if a byte array contains valid utf-8
* @param utf8: byte array
* @exception MalformedInputException if the byte array contains invalid utf-8
*/
public static void validateUTF8(byte[] utf8) throws MalformedInputException {
validateUTF8(utf8, 0, utf8.length);
}
/**
* Check to see if a byte array is valid utf-8
* @param utf8 the array of bytes
* @param start the offset of the first byte in the array
* @param len the length of the byte sequence
* @throws MalformedInputException if the byte array contains invalid bytes
*/
public static void validateUTF8(byte[] utf8, int start, int len)
throws MalformedInputException {
int count = start;
int leadByte = 0;
int length = 0;
int state = LEAD_BYTE;
while (count < start+len) {
int aByte = ((int) utf8[count] & 0xFF);
switch (state) {
case LEAD_BYTE:
leadByte = aByte;
length = bytesFromUTF8[aByte];
switch (length) {
case 0: // check for ASCII
if (leadByte > 0x7F)
throw new MalformedInputException(count);
break;
case 1:
if (leadByte < 0xC2 || leadByte > 0xDF)
throw new MalformedInputException(count);
state = TRAIL_BYTE_1;
break;
case 2:
if (leadByte < 0xE0 || leadByte > 0xEF)
throw new MalformedInputException(count);
state = TRAIL_BYTE_1;
break;
case 3:
if (leadByte < 0xF0 || leadByte > 0xF4)
throw new MalformedInputException(count);
state = TRAIL_BYTE_1;
break;
default:
// too long! Longest valid UTF-8 is 4 bytes (lead + three)
// or if < 0 we got a trail byte in the lead byte position
throw new MalformedInputException(count);
} // switch (length)
break;
case TRAIL_BYTE_1:
if (leadByte == 0xF0 && aByte < 0x90)
throw new MalformedInputException(count);
if (leadByte == 0xF4 && aByte > 0x8F)
throw new MalformedInputException(count);
if (leadByte == 0xE0 && aByte < 0xA0)
throw new MalformedInputException(count);
if (leadByte == 0xED && aByte > 0x9F)
throw new MalformedInputException(count);
// falls through to regular trail-byte test!!
case TRAIL_BYTE:
if (aByte < 0x80 || aByte > 0xBF)
throw new MalformedInputException(count);
if (--length == 0) {
state = LEAD_BYTE;
} else {
state = TRAIL_BYTE;
}
break;
} // switch (state)
count++;
}
}
/**
* Magic numbers for UTF-8. These are the number of bytes
* that <em>follow</em> a given lead byte. Trailing bytes
* have the value -1. The values 4 and 5 are presented in
* this table, even though valid UTF-8 cannot include the
* five and six byte sequences.
*/
static final int[] bytesFromUTF8 =
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0,
// trail bytes
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3,
3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5 };
/**
* Returns the next code point at the current position in
* the buffer. The buffer's position will be incremented.
* Any mark set on this buffer will be changed by this method!
*/
public static int bytesToCodePoint(ByteBuffer bytes) {
bytes.mark();
byte b = bytes.get();
bytes.reset();
int extraBytesToRead = bytesFromUTF8[(int)(b & 0xFF)];
if (extraBytesToRead < 0) return -1; // trailing byte!
int ch = 0;
switch (extraBytesToRead) {
case 5: ch += (int)(bytes.get() & 0xFF); ch <<= 6; /* remember, illegal UTF-8 */
case 4: ch += (int)(bytes.get() & 0xFF); ch <<= 6; /* remember, illegal UTF-8 */
case 3: ch += (int)(bytes.get() & 0xFF); ch <<= 6;
case 2: ch += (int)(bytes.get() & 0xFF); ch <<= 6;
case 1: ch += (int)(bytes.get() & 0xFF); ch <<= 6;
case 0: ch += (int)(bytes.get() & 0xFF);
}
ch -= offsetsFromUTF8[extraBytesToRead];
return ch;
}
static final int offsetsFromUTF8[] =
{ 0x00000000, 0x00003080,
0x000E2080, 0x03C82080, 0xFA082080, 0x82082080 };
/**
* For the given string, returns the number of UTF-8 bytes
* required to encode the string.
* @param string text to encode
* @return number of UTF-8 bytes required to encode
*/
public static int utf8Length(String string) {
CharacterIterator iter = new StringCharacterIterator(string);
char ch = iter.first();
int size = 0;
while (ch != CharacterIterator.DONE) {
if ((ch >= 0xD800) && (ch < 0xDC00)) {
// surrogate pair?
char trail = iter.next();
if ((trail > 0xDBFF) && (trail < 0xE000)) {
// valid pair
size += 4;
} else {
// invalid pair
size += 3;
iter.previous(); // rewind one
}
} else if (ch < 0x80) {
size++;
} else if (ch < 0x800) {
size += 2;
} else {
// ch < 0x10000, that is, the largest char value
size += 3;
}
ch = iter.next();
}
return size;
}
}