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A Java library for reading and writing iCalendar (*.ics) files
/** * Copyright (c) 2012, Ben Fortuna * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * o Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * o Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * o Neither the name of Ben Fortuna nor the names of any other contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package net.fortuna.ical4j.util; import java.util.regex.Pattern; /** * $Id$ [23-Apr-2004] * * Utility methods for working with parameters. * @author Ben Fortuna *method. * @param aValue an object to quote * @return a quoted string */ public static String quote(final Object aValue) { if (aValue != null) { return "\"" + aValue + "\""; } return "\"\""; } /** * Convenience method for removing surrounding quotes * from a string value. * @param aValue a string to remove quotes from * @return an un-quoted string */ public static String unquote(final String aValue) { if (aValue != null && aValue.startsWith("\"") && aValue.endsWith("\"")) { return aValue.substring(0, aValue.length() - 1).substring(1); } return aValue; } /** * Convenience method for escaping special characters. * @param aValue a string value to escape * @return an escaped representation of the specified * string */ public static String escape(final String aValue) { return escapePunctuation(escapeNewline(escapeBackslash(aValue))); } /** * Convenience method for replacing escaped special characters * with their original form. * @param aValue a string value to unescape * @return a string representation of the specified * string with escaped characters replaced with their * original form */ public static String unescape(final String aValue) { return unescapeBackslash(unescapeNewline(unescapePunctuation(aValue))); } private static String escapePunctuation(String value) { if (value != null) { return ESCAPE_PUNCTUATION_PATTERN.matcher(value).replaceAll("\\\\$1"); } return null; } private static String unescapePunctuation(String value) { if (value != null) { return UNESCAPE_PUNCTUATION_PATTERN.matcher(value).replaceAll("$1"); } return null; } public static String escapeNewline(String value) { if (value != null) { return ESCAPE_NEWLINE_PATTERN.matcher(value).replaceAll("\\\\n"); } return null; } private static String unescapeNewline(String value) { if (value != null) { return UNESCAPE_NEWLINE_PATTERN.matcher(value).replaceAll("\n"); } return null; } private static String escapeBackslash(String value) { if (value != null) { return ESCAPE_BACKSLASH_PATTERN.matcher(value).replaceAll("\\\\\\\\"); } return null; } private static String unescapeBackslash(String value) { if (value != null) { return UNESCAPE_BACKSLASH_PATTERN.matcher(value).replaceAll("\\\\"); } return null; } /** * Wraps* 4.3.11 Text * * Value Name: TEXT * * Purpose This value type is used to identify values that contain human * readable text. * * Formal Definition: The character sets supported by this revision of * iCalendar are UTF-8 and US ASCII thereof. The applicability to other * character sets is for future work. The value type is defined by the * following notation. * * text = *(TSAFE-CHAR / ":" / DQUOTE / ESCAPED-CHAR) * ; Folded according to description above * * ESCAPED-CHAR = "\\" / "\;" / "\," / "\N" / "\n") * ; \\ encodes \, \N or \n encodes newline * ; \; encodes ;, \, encodes , * * TSAFE-CHAR = %x20-21 / %x23-2B / %x2D-39 / %x3C-5B * %x5D-7E / NON-US-ASCII * ; Any character except CTLs not needed by the current * ; character set, DQUOTE, ";", ":", "\", "," * * Note: Certain other character sets may require modification of the * above definitions, but this is beyond the scope of this document. * * Description: If the property permits, multiple "text" values are * specified by a COMMA character (US-ASCII decimal 44) separated list * of values. * * The language in which the text is represented can be controlled by * the "LANGUAGE" property parameter. * * An intentional formatted text line break MUST only be included in a * "TEXT" property value by representing the line break with the * character sequence of BACKSLASH (US-ASCII decimal 92), followed by a * LATIN SMALL LETTER N (US-ASCII decimal 110) or a LATIN CAPITAL LETTER * N (US-ASCII decimal 78), that is "\n" or "\N". * * The "TEXT" property values may also contain special characters that * are used to signify delimiters, such as a COMMA character for lists * of values or a SEMICOLON character for structured values. In order to * support the inclusion of these special characters in "TEXT" property * values, they MUST be escaped with a BACKSLASH character. A BACKSLASH * character (US-ASCII decimal 92) in a "TEXT" property value MUST be * escaped with another BACKSLASH character. A COMMA character in a * "TEXT" property value MUST be escaped with a BACKSLASH character * (US-ASCII decimal 92). A SEMICOLON character in a "TEXT" property * value MUST be escaped with a BACKSLASH character (US-ASCII decimal * 92). However, a COLON character in a "TEXT" property value SHALL NOT * be escaped with a BACKSLASH character.Example: A multiple line value * of: * * Project XYZ Final Review * Conference Room - 3B * Come Prepared. * * would be represented as: * * Project XYZ Final Review\nConference Room - 3B\nCome Prepared. **/ public final class Strings { /** * Defines a regular expression representing all parameter strings that * should be quoted. */ public static final Pattern PARAM_QUOTE_PATTERN = Pattern.compile("[:;,]|[^\\p{ASCII}]"); private static final Pattern ESCAPE_PUNCTUATION_PATTERN = Pattern.compile("([,;])"); private static final Pattern UNESCAPE_PUNCTUATION_PATTERN = Pattern.compile("\\\\([,;\"])"); private static final Pattern ESCAPE_NEWLINE_PATTERN = Pattern.compile("\r?\n"); private static final Pattern UNESCAPE_NEWLINE_PATTERN = Pattern.compile("(?toString()java.lang.String.valueOf()to return an empty string * where the specified object is null. * @param object an object instance * @return a string representation of the object */ public static String valueOf(final Object object) { if (object == null) { return ""; } return object.toString(); } }