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LanguageTool is an Open Source proofreading software for English, French, German, Polish, Romanian, and more than 20 other languages. It finds many errors that a simple spell checker cannot detect like mixing up there/their and it detects some grammar problems.
/* LanguageTool, a natural language style checker
* Copyright (C) 2005 Daniel Naber (http://www.danielnaber.de)
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
* USA
*/
package org.languagetool.tools;
import com.google.common.xml.XmlEscapers;
import org.jetbrains.annotations.Nullable;
import org.languagetool.Language;
import java.io.*;
import java.lang.Character;
import java.util.Locale;
import java.util.Objects;
import java.util.regex.Pattern;
/**
* Tools for working with strings.
*
* @author Daniel Naber
*/
public final class StringTools {
/**
* Constants for printing XML rule matches.
*/
public enum ApiPrintMode {
/**
* Normally output the rule matches by starting and
* ending the XML/JSON output on every call.
*/
NORMAL_API,
/**
* Start XML/JSON output by printing the preamble and the
* start of the root element.
*/
START_API,
/**
* End XML/JSON output by closing the root element.
*/
END_API,
/**
* Simply continue rule match output.
*/
CONTINUE_API
}
private static final Pattern XML_COMMENT_PATTERN = Pattern.compile("", Pattern.DOTALL);
private static final Pattern XML_PATTERN = Pattern.compile("(?]+>", Pattern.DOTALL);
private StringTools() {
// only static stuff
}
/**
* Throw exception if the given string is null or empty or only whitespace.
*/
public static void assureSet(String s, String varName) {
Objects.requireNonNull(varName);
if (isEmpty(s.trim())) {
throw new IllegalArgumentException(varName + " cannot be empty or whitespace only");
}
}
/**
* Read the text stream using the given encoding.
*
* @param stream InputStream the stream to be read
* @param encoding the stream's character encoding, e.g. {@code utf-8}, or {@code null} to use the system encoding
* @return a string with the stream's content, lines separated by {@code \n} (note that {@code \n} will
* be added to the last line even if it is not in the stream)
* @since 2.3
*/
public static String readStream(InputStream stream, String encoding) throws IOException {
InputStreamReader isr = null;
StringBuilder sb = new StringBuilder();
try {
if (encoding == null) {
isr = new InputStreamReader(stream);
} else {
isr = new InputStreamReader(stream, encoding);
}
try (BufferedReader br = new BufferedReader(isr)) {
String line;
while ((line = br.readLine()) != null) {
sb.append(line);
sb.append('\n');
}
}
} finally {
if (isr != null) {
isr.close();
}
}
return sb.toString();
}
/**
* Returns true if the given string is made up of all-uppercase characters
* (ignoring characters for which no upper-/lowercase distinction exists).
*/
public static boolean isAllUppercase(String str) {
for (int i = 0; i < str.length(); i++) {
char c = str.charAt(i);
if (Character.isLetter(c) && Character.isLowerCase(c)) {
return false;
}
}
return true;
}
/**
* Returns true if the given string is mixed case, like {@code MixedCase} or {@code mixedCase}
* (but not {@code Mixedcase}).
* @param str input str
*/
public static boolean isMixedCase(String str) {
return !isAllUppercase(str)
&& !isCapitalizedWord(str)
&& isNotAllLowercase(str);
}
/**
* Returns true if str is made up of all-lowercase characters
* (ignoring characters for which no upper-/lowercase distinction exists).
* @since 2.5
*/
public static boolean isNotAllLowercase(String str) {
for (int i = 0; i < str.length(); i++) {
char c = str.charAt(i);
if (Character.isLetter(c) && !Character.isLowerCase(c)) {
return true;
}
}
return false;
}
/**
* @param str input string
* @return true if word starts with an uppercase letter and all other letters are lowercase
*/
public static boolean isCapitalizedWord(String str) {
if (!isEmpty(str) && Character.isUpperCase(str.charAt(0))) {
for (int i = 1; i < str.length(); i++) {
char c = str.charAt(i);
if (Character.isLetter(c) && !Character.isLowerCase(c)) {
return false;
}
}
return true;
}
return false;
}
/**
* Whether the first character of str is an uppercase character.
*/
public static boolean startsWithUppercase(String str) {
if (isEmpty(str)) {
return false;
}
return Character.isUpperCase(str.charAt(0));
}
/**
* Return str modified so that its first character is now an
* uppercase character. If str starts with non-alphabetic
* characters, such as quotes or parentheses, the first character is
* determined as the first alphabetic character.
*/
@Nullable
public static String uppercaseFirstChar(String str) {
return changeFirstCharCase(str, true);
}
/**
* Like {@link #uppercaseFirstChar(String)}, but handles a special case for Dutch (IJ in
* e.g. "ijsselmeer" -> "IJsselmeer").
* @param language the language, will be ignored if it's {@code null}
* @since 2.7
*/
@Nullable
public static String uppercaseFirstChar(String str, Language language) {
if (language != null && "nl".equals(language.getShortCode()) && str != null && str.toLowerCase().startsWith("ij")) {
// hack to fix https://github.com/languagetool-org/languagetool/issues/148
return "IJ" + str.substring(2);
} else {
return changeFirstCharCase(str, true);
}
}
/**
* Return str modified so that its first character is now an
* lowercase character. If str starts with non-alphabetic
* characters, such as quotes or parentheses, the first character is
* determined as the first alphabetic character.
*/
@Nullable
public static String lowercaseFirstChar(String str) {
return changeFirstCharCase(str, false);
}
/**
* Return str modified so that its first character is now an
* lowercase or uppercase character, depending on toUpperCase.
* If str starts with non-alphabetic
* characters, such as quotes or parentheses, the first character is
* determined as the first alphabetic character.
*/
@Nullable
private static String changeFirstCharCase(String str, boolean toUpperCase) {
if (isEmpty(str)) {
return str;
}
if (str.length() == 1) {
return toUpperCase ? str.toUpperCase(Locale.ENGLISH) : str.toLowerCase();
}
int pos = 0;
int len = str.length() - 1;
while (!Character.isLetterOrDigit(str.charAt(pos)) && len > pos) {
pos++;
}
char firstChar = str.charAt(pos);
return str.substring(0, pos)
+ (toUpperCase ? Character.toUpperCase(firstChar) : Character.toLowerCase(firstChar))
+ str.substring(pos + 1);
}
public static String readerToString(Reader reader) throws IOException {
StringBuilder sb = new StringBuilder();
int readBytes = 0;
char[] chars = new char[4000];
while (readBytes >= 0) {
readBytes = reader.read(chars, 0, 4000);
if (readBytes <= 0) {
break;
}
sb.append(new String(chars, 0, readBytes));
}
return sb.toString();
}
public static String streamToString(InputStream is, String charsetName) throws IOException {
try (InputStreamReader isr = new InputStreamReader(is, charsetName)) {
return readerToString(isr);
}
}
/**
* Calls {@link #escapeHTML(String)}.
*/
public static String escapeXML(String s) {
return escapeHTML(s);
}
/**
* @since 2.9
*/
public static String escapeForXmlAttribute(String s) {
return XmlEscapers.xmlAttributeEscaper().escape(s);
}
/**
* @since 2.9
*/
public static String escapeForXmlContent(String s) {
return XmlEscapers.xmlContentEscaper().escape(s);
}
/**
* Escapes these characters: less than, greater than, quote, ampersand.
*/
public static String escapeHTML(String s) {
// this version is much faster than using s.replaceAll()
StringBuilder sb = new StringBuilder();
int n = s.length();
for (int i = 0; i < n; i++) {
char c = s.charAt(i);
switch (c) {
case '<':
sb.append("<");
break;
case '>':
sb.append(">");
break;
case '&':
sb.append("&");
break;
case '"':
sb.append(""");
break;
default:
sb.append(c);
break;
}
}
return sb.toString();
}
/**
* Filters any whitespace characters. Useful for trimming the contents of
* token elements that cannot possibly contain any spaces, with the exception
* for a single space in a word (for example, if the language supports numbers
* formatted with spaces as single tokens, as Catalan in LanguageTool).
*
* @param s String to be filtered.
* @return Filtered s.
*/
public static String trimWhitespace(String s) {
StringBuilder filter = new StringBuilder();
String str = s.trim();
for (int i = 0; i < str.length(); i++) {
while (str.charAt(i) <= ' ' && i < str.length() &&
(str.charAt(i + 1) <= ' ' || i > 1 && str.charAt(i - 1) <= ' ')) {
i++;
}
char c = str.charAt(i);
if (c != '\n' && c != '\t' && c != '\r') {
filter.append(c);
}
}
return filter.toString();
}
/**
* eliminate special (unicode) characters, e.g. soft hyphens
* @since 4.3
* @param s String to filter
* @return s, with non-(alphanumeric, punctuation, space) characters deleted
*/
public static String trimSpecialCharacters(String s) {
// need unicode character classes -> (?U)
// lists all allowed character classes, replace everything else
return s.replaceAll("(?U)[^\\p{Space}\\p{Alnum}\\p{Punct}]", "");
}
/**
* Adds spaces before words that are not punctuation.
*
* @param word Word to add the preceding space.
* @param language
* Language of the word (to check typography conventions). Currently
* French convention of not adding spaces only before '.' and ',' is
* implemented; other languages assume that before ,.;:!? no spaces
* should be added.
* @return String containing a space or an empty string.
*/
public static String addSpace(String word, Language language) {
String space = " ";
if (word.length() == 1) {
char c = word.charAt(0);
if ("fr".equals(language.getShortCode())) {
if (c == '.' || c == ',') {
space = "";
}
} else {
if (c == '.' || c == ',' || c == ';' || c == ':' || c == '?' || c == '!') {
space = "";
}
}
}
return space;
}
/**
* Checks if a string contains a whitespace, including:
*
* - all Unicode whitespace
*
- the non-breaking space (U+00A0)
*
- the narrow non-breaking space (U+202F)
*
- the zero width space (U+200B), used in Khmer
*
* @param str String to check
* @return true if the string is a whitespace character
*/
public static boolean isWhitespace(String str) {
if ("\u0002".equals(str) // unbreakable field, e.g. a footnote number in OOo
|| "\u0001".equals(str)) { // breakable field in OOo
return false;
}
String trimStr = str.trim();
if (isEmpty(trimStr)) {
return true;
}
if (trimStr.length() == 1) {
if ("\u200B".equals(str)) {
// We need u200B to be detected as whitespace for Khmer, as it was the case before Java 7.
return true;
} else if ("\u00A0".equals(str) || "\u202F".equals(str)) { // non-breaking space and narrow non-breaking space
return true;
}
return Character.isWhitespace(trimStr.charAt(0));
}
return false;
}
/**
* Checks if a string is the non-breaking whitespace (\u00A0).
* @since 2.1
*/
public static boolean isNonBreakingWhitespace(String str) {
return "\u00A0".equals(str);
}
/**
* @param ch Character to check
* @return True if the character is a positive number (decimal digit from 1 to 9).
*/
public static boolean isPositiveNumber(char ch) {
return ch >= '1' && ch <= '9';
}
/**
* Helper method to replace calls to {@code "".equals()}.
*
* @param str String to check
* @return true if string is empty or {@code null}
*/
public static boolean isEmpty(String str) {
return str == null || str.length() == 0;
}
/**
* Simple XML filtering for XML tags.
* @param str XML string to be filtered.
* @return Filtered string without XML tags.
*/
public static String filterXML(String str) {
String s = str;
if (s.contains("<")) { // don't run slow regex unless we have to
s = XML_COMMENT_PATTERN.matcher(s).replaceAll(" ");
s = XML_PATTERN.matcher(s).replaceAll("");
}
return s;
}
@Nullable
public static String asString(CharSequence s) {
if (s == null) {
return null;
}
return s.toString();
}
/**
* @since 4.3
*/
public static boolean isParagraphEnd(String sentence, boolean singleLineBreaksMarksPara) {
boolean isParaEnd = false;
if (singleLineBreaksMarksPara) {
if (sentence.endsWith("\n") || sentence.endsWith("\n\r")) {
isParaEnd = true;
}
} else if (sentence.endsWith("\n\n") || sentence.endsWith("\n\r\n\r") || sentence.endsWith("\r\n\r\n")) {
isParaEnd = true;
}
return isParaEnd;
}
}