/*
* $Id: Strings.java,v 1.3 2006/04/05 10:50:07 fortuna Exp $ [23-Apr-2004]
*
* Copyright (c) 2004, 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;
/**
* Utility methods for working with parameters.
* @author Ben Fortuna
* <pre>
* 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.
* </pre>
*/
public final class Strings {
// private static final Pattern CHECK_ESCAPE = Pattern.compile("[,;\"\n\\\\]");
private static final Pattern CHECK_ESCAPE = Pattern.compile("[,;\n\\\\]");
private static final Pattern CHECK_UNESCAPE = Pattern.compile("\\\\");
// private static final Pattern ESCAPE_PATTERN_1 =
// Pattern.compile("([,;\"])");
private static final Pattern ESCAPE_PATTERN_1 =
Pattern.compile("([,;])");
private static final Pattern ESCAPE_PATTERN_2 =
Pattern.compile("[\r\n]+");
private static final Pattern ESCAPE_PATTERN_3 =
Pattern.compile("\\\\");
// private static final Pattern UNESCAPE_PATTERN_1 =
// Pattern.compile("\\\\([,;\"])");
private static final Pattern UNESCAPE_PATTERN_1 =
Pattern.compile("\\\\([,;])");
private static final Pattern UNESCAPE_PATTERN_2 =
Pattern.compile("\\\\n", Pattern.CASE_INSENSITIVE);
private static final Pattern UNESCAPE_PATTERN_3 =
Pattern.compile("\\\\\\\\");
/**
* A string used to denote the start (and end) of iCalendar content lines.
*/
public static final String LINE_SEPARATOR = "\r\n";
/**
* Constructor made private to prevent instantiation.
*/
private Strings() {
}
/**
* Convenience method for adding quotes. The specified
* object is converted to a string representation by
* calling its <code>toString()</code> 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) {
if (aValue != null && CHECK_ESCAPE.matcher(aValue).find()) {
return ESCAPE_PATTERN_1.matcher(
ESCAPE_PATTERN_2.matcher(
ESCAPE_PATTERN_3.matcher(aValue).replaceAll("\\\\\\\\"))
.replaceAll("\\\\n"))
.replaceAll("\\\\$1");
/*
return aValue.replaceAll("\\\\", "\\\\\\\\")
.replaceAll(";", "\\\\;")
.replaceAll(",", "\\\\,")
.replaceAll("\n", "\\\\n")
.replaceAll("\"", "\\\\\"");
*/
}
return 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) {
if (aValue != null && CHECK_UNESCAPE.matcher(aValue).find()) {
return UNESCAPE_PATTERN_3.matcher(
UNESCAPE_PATTERN_2.matcher(
UNESCAPE_PATTERN_1.matcher(aValue).replaceAll("$1"))
.replaceAll("\n"))
.replaceAll("\\\\");
/*
return aValue.replaceAll("\\\\\"", "\"")
.replaceAll("\\\\N", "\n")
.replaceAll("\\\\n", "\n")
.replaceAll("\\\\,", ",")
.replaceAll("\\\\;", ";")
.replaceAll("\\\\\\\\", "\\\\");
*/
}
return aValue;
}
/**
* Wraps <code>java.lang.String.valueOf()</code> to return an empty string
* where the specified object is null.
* @param object
* @return
*/
public static String valueOf(final Object object) {
if (object == null) {
return "";
}
return object.toString();
}
}