javaemul.internal.StringUtil Maven / Gradle / Ivy
/*
* Copyright 2023 Google Inc.
*
* 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
*
* https://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 javaemul.internal;
/** Utility methods for operating with Strings. */
public final class StringUtil {
private static final String whitespaceRegexStr =
"[\\u1680\\u180E\\u2000-\\u2006\\u2008-\\u200A\\u2028\\u2029\\u205F\\u3000\\uFEFF]"
+ "|[\\t-\\r ]"
+ "|[\\x1C-\\x1F]";
private static NativeRegExp whitespaceRegex;
public static boolean isWhitespace(String str) {
if (whitespaceRegex == null) {
// The regex would just be /\s/, but browsers handle non-breaking spaces inconsistently. Also,
// the Java definition includes separators.
whitespaceRegex = new NativeRegExp("^(" + whitespaceRegexStr + ")+$");
}
return whitespaceRegex.test(str);
}
private static final String spaceRegexStr =
"[\\u0020\\u00A0\\u1680\\u2000-\\u200A\\u202F\\u2028\\u2029\\u205F\\u3000]";
private static NativeRegExp spaceRegex;
public static boolean isSpace(String str) {
if (spaceRegex == null) {
spaceRegex = new NativeRegExp("^(" + spaceRegexStr + ")+$");
}
return spaceRegex.test(str);
}
private static NativeRegExp whitespaceOrSpaceRegex;
public static boolean isWhitespaceOrSpace(String str) {
if (whitespaceOrSpaceRegex == null) {
whitespaceOrSpaceRegex =
new NativeRegExp("^(" + whitespaceRegexStr + "|" + spaceRegexStr + ")+$");
}
return whitespaceOrSpaceRegex.test(str);
}
public static String replace(String str, char from, char to, boolean ignoreCase) {
return nativeReplace(str, escapeForRegExpSearch(from), to, /* replaceAll= */ true, ignoreCase);
}
public static String replace(String str, CharSequence from, CharSequence to, boolean ignoreCase) {
// Implementation note: This uses a regex replacement instead of
// a string literal replacement because Safari does not
// follow the spec for "$$" in the replacement string: it
// will insert a literal "$$". IE and Firefox, meanwhile,
// treat "$$" as "$".
return nativeReplace(
str,
escapeForRegExpSearch(from),
escapeForRegExpSearch(to),
/* replaceAll= */ true,
ignoreCase);
}
/**
* Regular expressions vary from the standard implementation. The regex parameter is
* interpreted by JavaScript as a JavaScript regular expression. For consistency, use only the
* subset of regular expression syntax common to both Java and JavaScript.
*
* TODO(jat): properly handle Java regex syntax
*/
public static String replaceAll(String str, String regex, String replace, boolean ignoreCase) {
return nativeReplace(str, regex, replace, /* replaceAll= */ true, ignoreCase);
}
/**
* Regular expressions vary from the standard implementation. The regex parameter is
* interpreted by JavaScript as a JavaScript regular expression. For consistency, use only the
* subset of regular expression syntax common to both Java and JavaScript.
*
*
TODO(jat): properly handle Java regex syntax
*/
public static String replaceFirst(String str, String regex, String replace, boolean ignoreCase) {
return nativeReplace(str, regex, replace, /* replaceAll= */ false, ignoreCase);
}
/** Replaces the first instance of the literal match with the literal replacement. */
public static String replaceFirstLiteral(String str, char from, char to, boolean ignoreCase) {
return nativeReplace(str, escapeForRegExpSearch(from), to, /* replaceAll= */ false, ignoreCase);
}
/** Replaces the first instance of the literal match with the literal replacement. */
public static String replaceFirstLiteral(
String str, CharSequence from, CharSequence to, boolean ignoreCase) {
return nativeReplace(
str,
escapeForRegExpSearch(from),
escapeForRegExpReplacement(to),
/* replaceAll= */ false,
ignoreCase);
}
private static String nativeReplace(
String str, String regex, String replace, boolean replaceAll, boolean ignoreCase) {
String flags = (replaceAll ? "g" : "") + (ignoreCase ? "i" : "");
return str.nativeReplace(new NativeRegExp(regex, flags), translateReplaceString(replace));
}
private static String nativeReplace(
String str, String regex, char replace, boolean replaceAll, boolean ignoreCase) {
String flags = (replaceAll ? "g" : "") + (ignoreCase ? "i" : "");
return str.nativeReplace(new NativeRegExp(regex, flags), replace);
}
/**
* This method converts Java-escaped dollar signs "\$" into JavaScript-escaped dollar signs "$$",
* and removes all other lone backslashes, which serve as escapes in Java but are passed through
* literally in JavaScript.
*/
private static String translateReplaceString(String replaceStr) {
int pos = 0;
while (0 <= (pos = replaceStr.indexOf("\\", pos))) {
if (replaceStr.charAt(pos + 1) == '$') {
replaceStr = replaceStr.substring(0, pos) + "$" + replaceStr.substring(++pos);
} else {
replaceStr = replaceStr.substring(0, pos) + replaceStr.substring(++pos);
}
}
return replaceStr;
}
private static String escapeForRegExpSearch(char c) {
// Translate 'from' into unicode escape sequence (\\u and a four-digit hexadecimal number).
// Escape sequence replacement is used instead of a string literal replacement
// in order to escape regexp special characters (e.g. '.').
String hex = Integer.toHexString(c);
return "\\u" + "0000".substring(hex.length()) + hex;
}
/** Escapes the given CharSerquence such that is can be used in a RegExp search. */
private static String escapeForRegExpSearch(CharSequence str) {
return str.toString().replaceAll("([/\\\\\\.\\*\\+\\?\\|\\(\\)\\[\\]\\{\\}$^])", "\\\\$1");
}
/** Escapes the given CharSerquence such that is can be used in a RegExp repleacement. */
private static String escapeForRegExpReplacement(CharSequence str) {
// Escape $ since it is for match backrefs and \ since it is used to escape $.
return str.toString().toString().replaceAll("\\\\", "\\\\\\\\").replaceAll("\\$", "\\\\$");
}
private StringUtil() {}
}