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SpotBugs: Because it's easy!
/*
* FindBugs - Find Bugs in Java programs
* Copyright (C) 2006, University of Maryland
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston MA 02111-1307, USA
*/
package edu.umd.cs.findbugs.util;
import java.util.Arrays;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
import org.apache.commons.text.StringEscapeUtils;
/**
* A class for static String utility methods.
*
* @author Brian Cole
*/
public class Strings {
/**
* This is intended to be semantically equivalent to
* source.replace(find, repl) but also compatible with JDK 1.4.
*
* @param source
* The String on which to operate
* @param find
* The literal substring to be replaced
* @param repl
* The literal replacement substring
* @return The resultant String after substitution
* @throws NullPointerException
* if any of the arguments are null
* @throws IllegalArgumentException
* if find has zero length
* @see java.lang.String#replace(CharSequence target, CharSequence
* replacement)
*/
@Deprecated
public static String replace(String source, String find, String repl) {
return source.replace(find, repl);
}
/**
* This is intended to be equivalent to Arrays.toString(a) but
* also compatible with JDK 1.4. This concatenates the results of calling
* String.valueOf() on each element of the array, so this won't work well
* for multi-dimensional arrays.
*
* @see java.lang.String#valueOf(Object)
* @see java.util.Arrays#toString(Object[])
* @see java.util.Arrays#deepToString(Object[])
*/
@Deprecated
public static String toString(final Object[] a) {
return Arrays.toString(a);
}
/**
* Trim trailing comma from given string.
*
* @param s
* a string
* @return the same string with trailing comma trimmed (if any)
*/
public static String trimComma(String s) {
if (s.endsWith(",")) {
s = s.substring(0, s.length() - 1);
}
return s;
}
/*
* XML escape/unescape routines: extend functionality of
* org.apache.commons.lang.{un,}escapeXml() by supporting low-value
* character escaping/unescaping
*/
private static final int XML_ALLOWED_LOW_CHARACTER_BOUND = 0x20;
private static boolean isInvalidXMLCharacter(int c) {
return (c < XML_ALLOWED_LOW_CHARACTER_BOUND && c >= 0x0
// low-value characters allowed by XML 1.0 spec
// '\uFFFE' () cannot be deserialized by SAX reader.
&& c != 0x9 && c != 0xA && c != 0xD)
|| c == 0xFFFE;
}
private static volatile boolean xmlLowValueEscapeStringsInitialized = false;
private static final String[] xmlLowValueEscapeStrings = new String[XML_ALLOWED_LOW_CHARACTER_BOUND];
private static final Object escapeInitLockObject = new Object();
/**
* Initializes the map of characters to be escaped and their corresponding
* escape sequences. This method will be invoked automatically the first
* time a string is escaped/unescaped.
*
* @see Extensible Markup
* Language (XML) 1.0 (Fifth Edition)
*/
public static void initializeEscapeMap() {
if (xmlLowValueEscapeStringsInitialized == true) {
return;
}
/*
* synchronize the lazy initialization so things don't break if FindBugs
* ever becomes multi-threaded (and also so FindBugs doesn't throw a
* warning about the thread safety of this operation)
*/
synchronized (escapeInitLockObject) {
if (xmlLowValueEscapeStringsInitialized == true) {
return;
}
for (int i = 0; i < XML_ALLOWED_LOW_CHARACTER_BOUND; i++) {
if (isInvalidXMLCharacter(i)) {
String escapedString = String.format("\\u%04x", i);
xmlLowValueEscapeStrings[i] = escapedString;
} else {
xmlLowValueEscapeStrings[i] = null;
}
}
xmlLowValueEscapeStringsInitialized = true;
}
}
/**
* Escape XML entities and illegal characters in the given string. This
* enhances the functionality of
* org.apache.commons.lang.StringEscapeUtils.escapeXml by escaping
* low-valued unprintable characters, which are not permitted by the W3C XML
* 1.0 specification.
*
* @param s
* a string
* @return the same string with characters not permitted by the XML
* specification escaped
* @see Extensible Markup
* Language (XML) 1.0 (Fifth Edition)
* @see org.apache.commons.lang.StringEscapeUtils
* javadoc
*/
public static String escapeXml(String s) {
initializeEscapeMap();
if (s == null || s.length() == 0) {
return s;
}
char[] sChars = s.toCharArray();
StringBuilder sb = new StringBuilder();
int lastReplacement = 0;
for (int i = 0; i < sChars.length; i++) {
if (isInvalidXMLCharacter(sChars[i])) {
// append intermediate string to string builder
sb.append(sChars, lastReplacement, i - lastReplacement);
// substitute control character with escape sequence
sb.append(sChars[i] == 0xFFFE ? "\\ufffe" : xmlLowValueEscapeStrings[sChars[i]]);
// advance last pointer past this character
lastReplacement = i + 1;
}
}
if (lastReplacement < sChars.length) {
sb.append(sChars, lastReplacement, sChars.length - lastReplacement);
}
return StringEscapeUtils.escapeXml11(sb.toString());
}
private static final String unicodeUnescapeMatchExpression = "(\\\\*)(\\\\u)(\\p{XDigit}{4})";
private static Pattern unescapePattern = null;
private static volatile boolean paternIsInitialized = false;
private static final Object unescapeInitLockObject = new Object();
/**
* Initialize regular expressions used in unescaping. This method will be
* invoked automatically the first time a string is unescaped.
*/
public static boolean initializeUnescapePattern() {
if (paternIsInitialized == true) {
return true;
}
synchronized (unescapeInitLockObject) {
if (paternIsInitialized == true) {
return true;
}
try {
unescapePattern = Pattern.compile(unicodeUnescapeMatchExpression);
} catch (PatternSyntaxException pse) {
/*
* the pattern is compiled from a final string, so this
* exception should never be thrown
*/
System.err.println("Imposible error: " + "static final regular expression pattern "
+ "failed to compile. Exception: " + pse.toString());
return false;
}
paternIsInitialized = true;
}
return true;
}
/**
* Unescape XML entities and illegal characters in the given string. This
* enhances the functionality of
* org.apache.commons.lang.StringEscapeUtils.unescapeXml by unescaping
* low-valued unprintable characters, which are not permitted by the W3C XML
* 1.0 specification.
*
* @param s
* a string
* @return the same string with XML entities/escape sequences unescaped
* @see Extensible Markup
* Language (XML) 1.0 (Fifth Edition)
* @see org.apache.commons.lang.StringEscapeUtils
* javadoc
*/
public static String unescapeXml(String s) {
initializeEscapeMap();
/*
* we can't escape the string if the pattern doesn't compile! (but that
* should never happen since the pattern is static)
*/
if (!initializeUnescapePattern()) {
return s;
}
if (s == null || s.length() == 0) {
return s;
}
/*
* skip this expensive check entirely if there are no substrings
* resembling Unicode escape sequences in the string to be unescaped
*/
if (s.contains("\\u")) {
StringBuffer sUnescaped = new StringBuffer();
Matcher m = unescapePattern.matcher(s);
while (m.find() == true) {
String slashes = m.group(1);
String digits = m.group(3);
int escapeCode;
try {
escapeCode = Integer.parseInt(digits, 16);
} catch (NumberFormatException nfe) {
/*
* the static regular expression string should guarantee
* that this exception is never thrown
*/
System.err.println("Impossible error: escape sequence '" + digits + "' is not a valid hex number! "
+ "Exception: " + nfe.toString());
return s;
}
if (slashes != null && slashes.length() % 2 == 0 && isInvalidXMLCharacter(escapeCode)) {
Character escapedSequence = Character.valueOf((char) escapeCode);
/*
* slashes are apparently escaped when the string buffer is
* converted to a string, so double them to make sure the
* correct number appear in the final representation
*/
m.appendReplacement(sUnescaped, slashes + slashes + escapedSequence.toString());
}
}
m.appendTail(sUnescaped);
s = sUnescaped.toString();
}
return StringEscapeUtils.unescapeXml(s);
}
public static String escapeLFCRBackSlash(String s) {
s = s.replace("\\", "\\\\");
s = s.replace("\r", "\\r");
s = s.replace("\n", "\\n");
return s;
}
}