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/*
* Copyright 2012 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 io.netty.util.internal;
import java.io.IOException;
import static io.netty.util.internal.ObjectUtil.*;
/**
* String utility class.
*/
public final class StringUtil {
public static final String NEWLINE = SystemPropertyUtil.get("line.separator", "\n");
public static final char DOUBLE_QUOTE = '\"';
public static final char COMMA = ',';
public static final char LINE_FEED = '\n';
public static final char CARRIAGE_RETURN = '\r';
public static final String EMPTY_STRING = "";
private static final String[] BYTE2HEX_PAD = new String[256];
private static final String[] BYTE2HEX_NOPAD = new String[256];
/**
* 2 - Quote character at beginning and end.
* 5 - Extra allowance for anticipated escape characters that may be added.
*/
private static final int CSV_NUMBER_ESCAPE_CHARACTERS = 2 + 5;
private static final char PACKAGE_SEPARATOR_CHAR = '.';
static {
// Generate the lookup table that converts a byte into a 2-digit hexadecimal integer.
int i;
for (i = 0; i < 10; i ++) {
BYTE2HEX_PAD[i] = "0" + i;
BYTE2HEX_NOPAD[i] = String.valueOf(i);
}
for (; i < 16; i ++) {
char c = (char) ('a' + i - 10);
BYTE2HEX_PAD[i] = "0" + c;
BYTE2HEX_NOPAD[i] = String.valueOf(c);
}
for (; i < BYTE2HEX_PAD.length; i ++) {
String str = Integer.toHexString(i);
BYTE2HEX_PAD[i] = str;
BYTE2HEX_NOPAD[i] = str;
}
}
private StringUtil() {
// Unused.
}
/**
* Get the item after one char delim if the delim is found (else null).
* This operation is a simplified and optimized
* version of {@link String#split(String, int)}.
*/
public static String substringAfter(String value, char delim) {
int pos = value.indexOf(delim);
if (pos >= 0) {
return value.substring(pos + 1);
}
return null;
}
/**
* Checks if two strings have the same suffix of specified length
*
* @param s string
* @param p string
* @param len length of the common suffix
* @return true if both s and p are not null and both have the same suffix. Otherwise - false
*/
public static boolean commonSuffixOfLength(String s, String p, int len) {
return s != null && p != null && len >= 0 && s.regionMatches(s.length() - len, p, p.length() - len, len);
}
/**
* Converts the specified byte value into a 2-digit hexadecimal integer.
*/
public static String byteToHexStringPadded(int value) {
return BYTE2HEX_PAD[value & 0xff];
}
/**
* Converts the specified byte value into a 2-digit hexadecimal integer and appends it to the specified buffer.
*/
public static T byteToHexStringPadded(T buf, int value) {
try {
buf.append(byteToHexStringPadded(value));
} catch (IOException e) {
PlatformDependent.throwException(e);
}
return buf;
}
/**
* Converts the specified byte array into a hexadecimal value.
*/
public static String toHexStringPadded(byte[] src) {
return toHexStringPadded(src, 0, src.length);
}
/**
* Converts the specified byte array into a hexadecimal value.
*/
public static String toHexStringPadded(byte[] src, int offset, int length) {
return toHexStringPadded(new StringBuilder(length << 1), src, offset, length).toString();
}
/**
* Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.
*/
public static T toHexStringPadded(T dst, byte[] src) {
return toHexStringPadded(dst, src, 0, src.length);
}
/**
* Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.
*/
public static T toHexStringPadded(T dst, byte[] src, int offset, int length) {
final int end = offset + length;
for (int i = offset; i < end; i ++) {
byteToHexStringPadded(dst, src[i]);
}
return dst;
}
/**
* Converts the specified byte value into a hexadecimal integer.
*/
public static String byteToHexString(int value) {
return BYTE2HEX_NOPAD[value & 0xff];
}
/**
* Converts the specified byte value into a hexadecimal integer and appends it to the specified buffer.
*/
public static T byteToHexString(T buf, int value) {
try {
buf.append(byteToHexString(value));
} catch (IOException e) {
PlatformDependent.throwException(e);
}
return buf;
}
/**
* Converts the specified byte array into a hexadecimal value.
*/
public static String toHexString(byte[] src) {
return toHexString(src, 0, src.length);
}
/**
* Converts the specified byte array into a hexadecimal value.
*/
public static String toHexString(byte[] src, int offset, int length) {
return toHexString(new StringBuilder(length << 1), src, offset, length).toString();
}
/**
* Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.
*/
public static T toHexString(T dst, byte[] src) {
return toHexString(dst, src, 0, src.length);
}
/**
* Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.
*/
public static T toHexString(T dst, byte[] src, int offset, int length) {
assert length >= 0;
if (length == 0) {
return dst;
}
final int end = offset + length;
final int endMinusOne = end - 1;
int i;
// Skip preceding zeroes.
for (i = offset; i < endMinusOne; i ++) {
if (src[i] != 0) {
break;
}
}
byteToHexString(dst, src[i ++]);
int remaining = end - i;
toHexStringPadded(dst, src, i, remaining);
return dst;
}
/**
* Helper to decode half of a hexadecimal number from a string.
* @param c The ASCII character of the hexadecimal number to decode.
* Must be in the range {@code [0-9a-fA-F]}.
* @return The hexadecimal value represented in the ASCII character
* given, or {@code -1} if the character is invalid.
*/
public static int decodeHexNibble(final char c) {
// Character.digit() is not used here, as it addresses a larger
// set of characters (both ASCII and full-width latin letters).
if (c >= '0' && c <= '9') {
return c - '0';
}
if (c >= 'A' && c <= 'F') {
return c - 'A' + 0xA;
}
if (c >= 'a' && c <= 'f') {
return c - 'a' + 0xA;
}
return -1;
}
/**
* Decode a 2-digit hex byte from within a string.
*/
public static byte decodeHexByte(CharSequence s, int pos) {
int hi = decodeHexNibble(s.charAt(pos));
int lo = decodeHexNibble(s.charAt(pos + 1));
if (hi == -1 || lo == -1) {
throw new IllegalArgumentException(String.format(
"invalid hex byte '%s' at index %d of '%s'", s.subSequence(pos, pos + 2), pos, s));
}
return (byte) ((hi << 4) + lo);
}
/**
* Decodes part of a string with hex dump
*
* @param hexDump a {@link CharSequence} which contains the hex dump
* @param fromIndex start of hex dump in {@code hexDump}
* @param length hex string length
*/
public static byte[] decodeHexDump(CharSequence hexDump, int fromIndex, int length) {
if (length < 0 || (length & 1) != 0) {
throw new IllegalArgumentException("length: " + length);
}
if (length == 0) {
return EmptyArrays.EMPTY_BYTES;
}
byte[] bytes = new byte[length >>> 1];
for (int i = 0; i < length; i += 2) {
bytes[i >>> 1] = decodeHexByte(hexDump, fromIndex + i);
}
return bytes;
}
/**
* Decodes a hex dump
*/
public static byte[] decodeHexDump(CharSequence hexDump) {
return decodeHexDump(hexDump, 0, hexDump.length());
}
/**
* The shortcut to {@link #simpleClassName(Class) simpleClassName(o.getClass())}.
*/
public static String simpleClassName(Object o) {
if (o == null) {
return "null_object";
} else {
return simpleClassName(o.getClass());
}
}
/**
* Generates a simplified name from a {@link Class}. Similar to {@link Class#getSimpleName()}, but it works fine
* with anonymous classes.
*/
public static String simpleClassName(Class clazz) {
String className = ObjectUtil.checkNotNull(clazz, "clazz").getName();
final int lastDotIdx = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR);
if (lastDotIdx > -1) {
return className.substring(lastDotIdx + 1);
}
return className;
}
/**
* Escapes the specified value, if necessary according to
* RFC-4180.
*
* @param value The value which will be escaped according to
* RFC-4180
* @return {@link CharSequence} the escaped value if necessary, or the value unchanged
*/
public static CharSequence escapeCsv(CharSequence value) {
int length = checkNotNull(value, "value").length();
if (length == 0) {
return value;
}
int last = length - 1;
boolean quoted = isDoubleQuote(value.charAt(0)) && isDoubleQuote(value.charAt(last)) && length != 1;
boolean foundSpecialCharacter = false;
boolean escapedDoubleQuote = false;
StringBuilder escaped = new StringBuilder(length + CSV_NUMBER_ESCAPE_CHARACTERS).append(DOUBLE_QUOTE);
for (int i = 0; i < length; i++) {
char current = value.charAt(i);
switch (current) {
case DOUBLE_QUOTE:
if (i == 0 || i == last) {
if (!quoted) {
escaped.append(DOUBLE_QUOTE);
} else {
continue;
}
} else {
boolean isNextCharDoubleQuote = isDoubleQuote(value.charAt(i + 1));
if (!isDoubleQuote(value.charAt(i - 1)) &&
(!isNextCharDoubleQuote || i + 1 == last)) {
escaped.append(DOUBLE_QUOTE);
escapedDoubleQuote = true;
}
break;
}
case LINE_FEED:
case CARRIAGE_RETURN:
case COMMA:
foundSpecialCharacter = true;
}
escaped.append(current);
}
return escapedDoubleQuote || foundSpecialCharacter && !quoted ?
escaped.append(DOUBLE_QUOTE) : value;
}
/**
* Unescapes the specified escaped CSV field, if necessary according to
* RFC-4180.
*
* @param value The escaped CSV field which will be unescaped according to
* RFC-4180
* @return {@link CharSequence} the unescaped value if necessary, or the value unchanged
*/
public static CharSequence unescapeCsv(CharSequence value) {
int length = checkNotNull(value, "value").length();
if (length == 0) {
return value;
}
int last = length - 1;
boolean quoted = isDoubleQuote(value.charAt(0)) && isDoubleQuote(value.charAt(last)) && length != 1;
if (!quoted) {
validateCsvFormat(value);
return value;
}
StringBuilder unescaped = InternalThreadLocalMap.get().stringBuilder();
for (int i = 1; i < last; i++) {
char current = value.charAt(i);
if (current == DOUBLE_QUOTE) {
if (isDoubleQuote(value.charAt(i + 1)) && (i + 1) != last) {
// Followed by a double-quote but not the last character
// Just skip the next double-quote
i++;
} else {
// Not followed by a double-quote or the following double-quote is the last character
throw newInvalidEscapedCsvFieldException(value, i);
}
}
unescaped.append(current);
}
return unescaped.toString();
}
/**
* Validate if {@code value} is a valid csv field without double-quotes.
*
* @throws IllegalArgumentException if {@code value} needs to be encoded with double-quotes.
*/
private static void validateCsvFormat(CharSequence value) {
int length = value.length();
for (int i = 0; i < length; i++) {
switch (value.charAt(i)) {
case DOUBLE_QUOTE:
case LINE_FEED:
case CARRIAGE_RETURN:
case COMMA:
// If value contains any special character, it should be enclosed with double-quotes
throw newInvalidEscapedCsvFieldException(value, i);
default:
}
}
}
private static IllegalArgumentException newInvalidEscapedCsvFieldException(CharSequence value, int index) {
return new IllegalArgumentException("invalid escaped CSV field: " + value + " index: " + index);
}
/**
* Get the length of a string, {@code null} input is considered {@code 0} length.
*/
public static int length(String s) {
return s == null ? 0 : s.length();
}
/**
* Determine if a string is {@code null} or {@link String#isEmpty()} returns {@code true}.
*/
public static boolean isNullOrEmpty(String s) {
return s == null || s.isEmpty();
}
/**
* Determine if {@code c} lies within the range of values defined for
* Surrogate Code Point.
* @param c the character to check.
* @return {@code true} if {@code c} lies within the range of values defined for
* Surrogate Code Point. {@code false} otherwise.
*/
public static boolean isSurrogate(char c) {
return c >= '\uD800' && c <= '\uDFFF';
}
private static boolean isDoubleQuote(char c) {
return c == DOUBLE_QUOTE;
}
}
