PropertiesConfigurationLayout.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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
*
* http://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 org.apache.commons.configuration2;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;
import java.net.URL;
import java.util.ArrayDeque;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Properties;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.commons.configuration2.event.ConfigurationEvent;
import org.apache.commons.configuration2.event.EventListener;
import org.apache.commons.configuration2.ex.ConfigurationException;
import org.apache.commons.configuration2.ex.ConfigurationRuntimeException;
import org.apache.commons.lang3.StringUtils;
/**
* <p>
* A helper class used by {@link PropertiesConfiguration} to keep the layout of a properties file.
* </p>
* <p>
* Instances of this class are associated with a {@code PropertiesConfiguration} object. They are responsible for
* analyzing properties files and for extracting as much information about the file layout (e.g. empty lines, comments)
* as possible. When the properties file is written back again it should be close to the original.
* </p>
* <p>
* The {@code PropertiesConfigurationLayout} object associated with a {@code PropertiesConfiguration} object can be
* obtained using the {@code getLayout()} method of the configuration. Then the methods provided by this class can be
* used to alter the properties file's layout.
* </p>
* <p>
* Implementation note: This is a very simple implementation, which is far away from being perfect, i.e. the original
* layout of a properties file won't be reproduced in all cases. One limitation is that comments for multi-valued
* property keys are concatenated. Maybe this implementation can later be improved.
* </p>
* <p>
* To get an impression how this class works consider the following properties file:
* </p>
*
* <pre>
* # A demo configuration file
* # for Demo App 1.42
*
* # Application name
* AppName=Demo App
*
* # Application vendor
* AppVendor=DemoSoft
*
*
* # GUI properties
* # Window Color
* windowColors=0xFFFFFF,0x000000
*
* # Include some setting
* include=settings.properties
* # Another vendor
* AppVendor=TestSoft
* </pre>
*
* <p>
* For this example the following points are relevant:
* </p>
* <ul>
* <li>The first two lines are set as header comment. The header comment is determined by the last blank line before the
* first property definition.</li>
* <li>For the property {@code AppName} one comment line and one leading blank line is stored.</li>
* <li>For the property {@code windowColors} two comment lines and two leading blank lines are stored.</li>
* <li>Include files is something this class cannot deal with well. When saving the properties configuration back, the
* included properties are simply contained in the original file. The comment before the include property is
* skipped.</li>
* <li>For all properties except for {@code AppVendor} the "single line" flag is set. This is relevant only
* for {@code windowColors}, which has multiple values defined in one line using the separator character.</li>
* <li>The {@code AppVendor} property appears twice. The comment lines are concatenated, so that
* {@code layout.getComment("AppVendor");} will result in {@code Application vendor<CR>Another vendor}, with
* {@code <CR>} meaning the line separator. In addition the "single line" flag is set to <b>false</b>
* for this property. When the file is saved, two property definitions will be written (in series).</li>
* </ul>
*
* @since 1.3
*/
public class PropertiesConfigurationLayout implements EventListener<ConfigurationEvent> {
/**
* A helper class for storing all layout related information for a configuration property.
*/
static class PropertyLayoutData implements Cloneable {
/** Stores the comment for the property. */
private StringBuffer comment;
/** The separator to be used for this property. */
private String separator;
/** Stores the number of blank lines before this property. */
private int blankLines;
/** Stores the single line property. */
private boolean singleLine;
/**
* Creates a new instance of {@code PropertyLayoutData}.
*/
public PropertyLayoutData() {
singleLine = true;
separator = PropertiesConfiguration.DEFAULT_SEPARATOR;
}
/**
* Adds a comment for this property. If already a comment exists, the new comment is added (separated by a newline).
*
* @param s the comment to add
*/
public void addComment(final String s) {
if (s != null) {
if (comment == null) {
comment = new StringBuffer(s);
} else {
comment.append(CR).append(s);
}
}
}
/**
* Creates a copy of this object.
*
* @return the copy
*/
@Override
public PropertyLayoutData clone() {
try {
final PropertyLayoutData copy = (PropertyLayoutData) super.clone();
if (comment != null) {
// must copy string buffer, too
copy.comment = new StringBuffer(getComment());
}
return copy;
} catch (final CloneNotSupportedException cnex) {
// This cannot happen!
throw new ConfigurationRuntimeException(cnex);
}
}
/**
* Gets the number of blank lines before this property.
*
* @return the number of blank lines before this property
* @deprecated Use {#link {@link #getBlankLines()}}.
*/
@Deprecated
public int getBlancLines() {
return getBlankLines();
}
/**
* Gets the number of blank lines before this property.
*
* @return the number of blank lines before this property
* @since 2.8.0
*/
public int getBlankLines() {
return blankLines;
}
/**
* Gets the comment for this property. The comment is returned as it is, without processing of comment characters.
*
* @return the comment (can be <b>null</b>)
*/
public String getComment() {
return Objects.toString(comment, null);
}
/**
* Gets the separator that was used for this property.
*
* @return the property separator
*/
public String getSeparator() {
return separator;
}
/**
* Returns the single line flag.
*
* @return the single line flag
*/
public boolean isSingleLine() {
return singleLine;
}
/**
* Sets the number of properties before this property.
*
* @param blankLines the number of properties before this property
* @deprecated Use {@link #setBlankLines(int)}.
*/
@Deprecated
public void setBlancLines(final int blankLines) {
setBlankLines(blankLines);
}
/**
* Sets the number of properties before this property.
*
* @param blankLines the number of properties before this property
* @since 2.8.0
*/
public void setBlankLines(final int blankLines) {
this.blankLines = blankLines;
}
/**
* Sets the comment for this property.
*
* @param s the new comment (can be <b>null</b>)
*/
public void setComment(final String s) {
if (s == null) {
comment = null;
} else {
comment = new StringBuffer(s);
}
}
/**
* Sets the separator to be used for the represented property.
*
* @param separator the property separator
*/
public void setSeparator(final String separator) {
this.separator = separator;
}
/**
* Sets the single line flag.
*
* @param singleLine the single line flag
*/
public void setSingleLine(final boolean singleLine) {
this.singleLine = singleLine;
}
}
/** Constant for the line break character. */
private static final String CR = "\n";
/** Constant for the default comment prefix. */
private static final String COMMENT_PREFIX = "# ";
/**
* Helper method for generating a comment string. Depending on the boolean argument the resulting string either has no
* comment characters or a leading comment character at each line.
*
* @param comment the comment string to be processed
* @param commentChar determines the presence of comment characters
* @return the canonical comment string (can be <b>null</b>)
*/
private static String constructCanonicalComment(final String comment, final boolean commentChar) {
return comment == null ? null : trimComment(comment, commentChar);
}
/**
* Tests whether a line is a comment, i.e. whether it starts with a comment character.
*
* @param line the line
* @return a flag if this is a comment line
*/
static boolean isCommentLine(final String line) {
return PropertiesConfiguration.isCommentLine(line);
}
/**
* Either removes the comment character from the given comment line or ensures that the line starts with a comment
* character.
*
* @param s the comment line
* @param comment if <b>true</b>, a comment character will always be enforced; if <b>false</b>, it will be removed
* @return the line without comment character
*/
static String stripCommentChar(final String s, final boolean comment) {
if (StringUtils.isBlank(s) || isCommentLine(s) == comment) {
return s;
}
if (!comment) {
int pos = 0;
// find first comment character
while (PropertiesConfiguration.COMMENT_CHARS.indexOf(s.charAt(pos)) < 0) {
pos++;
}
// Remove leading spaces
pos++;
while (pos < s.length() && Character.isWhitespace(s.charAt(pos))) {
pos++;
}
return pos < s.length() ? s.substring(pos) : StringUtils.EMPTY;
}
return COMMENT_PREFIX + s;
}
/**
* Trims a comment. This method either removes all comment characters from the given string, leaving only the plain
* comment text or ensures that every line starts with a valid comment character.
*
* @param s the string to be processed
* @param comment if <b>true</b>, a comment character will always be enforced; if <b>false</b>, it will be removed
* @return the trimmed comment
*/
static String trimComment(final String s, final boolean comment) {
final StringBuilder buf = new StringBuilder(s.length());
int lastPos = 0;
int pos;
do {
pos = s.indexOf(CR, lastPos);
if (pos >= 0) {
final String line = s.substring(lastPos, pos);
buf.append(stripCommentChar(line, comment)).append(CR);
lastPos = pos + CR.length();
}
} while (pos >= 0);
if (lastPos < s.length()) {
buf.append(stripCommentChar(s.substring(lastPos), comment));
}
return buf.toString();
}
/**
* Helper method for writing a comment line. This method ensures that the correct line separator is used if the comment
* spans multiple lines.
*
* @param writer the writer
* @param comment the comment to write
* @throws IOException if an IO error occurs
*/
private static void writeComment(final PropertiesConfiguration.PropertiesWriter writer, final String comment) throws IOException {
if (comment != null) {
writer.writeln(StringUtils.replace(comment, CR, writer.getLineSeparator()));
}
}
/** Stores a map with the contained layout information. */
private final Map<String, PropertyLayoutData> layoutData;
/** Stores the header comment. */
private String headerComment;
/** Stores the footer comment. */
private String footerComment;
/** The global separator that will be used for all properties. */
private String globalSeparator;
/** The line separator. */
private String lineSeparator;
/** A counter for determining nested load calls. */
private final AtomicInteger loadCounter;
/** Stores the force single line flag. */
private boolean forceSingleLine;
/** Seen includes. */
private final ArrayDeque<URL> seenStack = new ArrayDeque<>();
/**
* Creates a new, empty instance of {@code PropertiesConfigurationLayout}.
*/
public PropertiesConfigurationLayout() {
this(null);
}
/**
* Creates a new instance of {@code PropertiesConfigurationLayout} and copies the data of the specified layout object.
*
* @param c the layout object to be copied
*/
public PropertiesConfigurationLayout(final PropertiesConfigurationLayout c) {
loadCounter = new AtomicInteger();
layoutData = new LinkedHashMap<>();
if (c != null) {
copyFrom(c);
}
}
/**
* Checks if parts of the passed in comment can be used as header comment. This method checks whether a header comment
* can be defined (i.e. whether this is the first comment in the loaded file). If this is the case, it is searched for
* the latest blank line. This line will mark the end of the header comment. The return value is the index of the first
* line in the passed in list, which does not belong to the header comment.
*
* @param commentLines the comment lines
* @return the index of the next line after the header comment
*/
private int checkHeaderComment(final List<String> commentLines) {
if (loadCounter.get() == 1 && layoutData.isEmpty()) {
int index = commentLines.size() - 1;
// strip comments that belong to first key
while (index >= 0 && StringUtils.isNotEmpty(commentLines.get(index))) {
index--;
}
// strip blank lines
while (index >= 0 && StringUtils.isEmpty(commentLines.get(index))) {
index--;
}
if (getHeaderComment() == null) {
setHeaderComment(extractComment(commentLines, 0, index));
}
return index + 1;
}
return 0;
}
/**
* Removes all content from this layout object.
*/
private void clear() {
seenStack.clear();
layoutData.clear();
setHeaderComment(null);
setFooterComment(null);
}
/**
* Copies the data from the given layout object.
*
* @param c the layout object to copy
*/
private void copyFrom(final PropertiesConfigurationLayout c) {
c.getKeys().forEach(key -> layoutData.put(key, c.layoutData.get(key).clone()));
setHeaderComment(c.getHeaderComment());
setFooterComment(c.getFooterComment());
}
/**
* Extracts a comment string from the given range of the specified comment lines. The single lines are added using a
* line feed as separator.
*
* @param commentLines a list with comment lines
* @param from the start index
* @param to the end index (inclusive)
* @return the comment string (<b>null</b> if it is undefined)
*/
private String extractComment(final List<String> commentLines, final int from, final int to) {
if (to < from) {
return null;
}
final StringBuilder buf = new StringBuilder(commentLines.get(from));
for (int i = from + 1; i <= to; i++) {
buf.append(CR);
buf.append(commentLines.get(i));
}
return buf.toString();
}
/**
* Returns a layout data object for the specified key. If this is a new key, a new object is created and initialized
* with default values.
*
* @param key the key
* @return the corresponding layout data object
*/
private PropertyLayoutData fetchLayoutData(final String key) {
if (key == null) {
throw new IllegalArgumentException("Property key must not be null!");
}
// PropertyLayoutData defaults to singleLine = true
return layoutData.computeIfAbsent(key, k -> new PropertyLayoutData());
}
/**
* Gets the number of blank lines before this property key. If this key does not exist, 0 will be returned.
*
* @param key the property key
* @return the number of blank lines before the property definition for this key
* @deprecated Use {@link #getBlankLinesBefore(String)}.
*/
@Deprecated
public int getBlancLinesBefore(final String key) {
return getBlankLinesBefore(key);
}
/**
* Gets the number of blank lines before this property key. If this key does not exist, 0 will be returned.
*
* @param key the property key
* @return the number of blank lines before the property definition for this key
*/
public int getBlankLinesBefore(final String key) {
return fetchLayoutData(key).getBlankLines();
}
/**
* Gets the comment for the specified property key in a canonical form. "Canonical" means that either all
* lines start with a comment character or none. If the {@code commentChar} parameter is <b>false</b>, all comment
* characters are removed, so that the result is only the plain text of the comment. Otherwise it is ensured that each
* line of the comment starts with a comment character. Also, line breaks in the comment are normalized to the line
* separator "\n".
*
* @param key the key of the property
* @param commentChar determines whether all lines should start with comment characters or not
* @return the canonical comment for this key (can be <b>null</b>)
*/
public String getCanonicalComment(final String key, final boolean commentChar) {
return constructCanonicalComment(getComment(key), commentChar);
}
/**
* Gets the footer comment of the represented properties file in a canonical form. This method works like
* {@code getCanonicalHeaderComment()}, but reads the footer comment.
*
* @param commentChar determines the presence of comment characters
* @return the footer comment (can be <b>null</b>)
* @see #getCanonicalHeaderComment(boolean)
* @since 2.0
*/
public String getCanonicalFooterCooment(final boolean commentChar) {
return constructCanonicalComment(getFooterComment(), commentChar);
}
/**
* Gets the header comment of the represented properties file in a canonical form. With the {@code commentChar}
* parameter it can be specified whether comment characters should be stripped or be always present.
*
* @param commentChar determines the presence of comment characters
* @return the header comment (can be <b>null</b>)
*/
public String getCanonicalHeaderComment(final boolean commentChar) {
return constructCanonicalComment(getHeaderComment(), commentChar);
}
/**
* Gets the comment for the specified property key. The comment is returned as it was set (either manually by calling
* {@code setComment()} or when it was loaded from a properties file). No modifications are performed.
*
* @param key the key of the property
* @return the comment for this key (can be <b>null</b>)
*/
public String getComment(final String key) {
return fetchLayoutData(key).getComment();
}
/**
* Gets the footer comment of the represented properties file. This method returns the footer comment exactly as it
* was set using {@code setFooterComment()} or extracted from the loaded properties file.
*
* @return the footer comment (can be <b>null</b>)
* @since 2.0
*/
public String getFooterComment() {
return footerComment;
}
/**
* Gets the global separator.
*
* @return the global properties separator
* @since 1.7
*/
public String getGlobalSeparator() {
return globalSeparator;
}
/**
* Gets the header comment of the represented properties file. This method returns the header comment exactly as it
* was set using {@code setHeaderComment()} or extracted from the loaded properties file.
*
* @return the header comment (can be <b>null</b>)
*/
public String getHeaderComment() {
return headerComment;
}
/**
* Gets a set with all property keys managed by this object.
*
* @return a set with all contained property keys
*/
public Set<String> getKeys() {
return layoutData.keySet();
}
/**
* Gets the line separator.
*
* @return the line separator
* @since 1.7
*/
public String getLineSeparator() {
return lineSeparator;
}
/**
* Gets the separator for the property with the given key.
*
* @param key the property key
* @return the property separator for this property
* @since 1.7
*/
public String getSeparator(final String key) {
return fetchLayoutData(key).getSeparator();
}
/**
* Returns the "force single line" flag.
*
* @return the force single line flag
* @see #setForceSingleLine(boolean)
*/
public boolean isForceSingleLine() {
return forceSingleLine;
}
/**
* Returns a flag whether the specified property is defined on a single line. This is meaningful only if this property
* has multiple values.
*
* @param key the property key
* @return a flag if this property is defined on a single line
*/
public boolean isSingleLine(final String key) {
return fetchLayoutData(key).isSingleLine();
}
/**
* Reads a properties file and stores its internal structure. The found properties will be added to the specified
* configuration object.
*
* @param config the associated configuration object
* @param reader the reader to the properties file
* @throws ConfigurationException if an error occurs
*/
public void load(final PropertiesConfiguration config, final Reader reader) throws ConfigurationException {
loadCounter.incrementAndGet();
@SuppressWarnings("resource") // createPropertiesReader wraps the reader.
final PropertiesConfiguration.PropertiesReader pReader = config.getIOFactory().createPropertiesReader(reader);
try {
while (pReader.nextProperty()) {
if (config.propertyLoaded(pReader.getPropertyName(), pReader.getPropertyValue(), seenStack)) {
final boolean contained = layoutData.containsKey(pReader.getPropertyName());
int blankLines = 0;
int idx = checkHeaderComment(pReader.getCommentLines());
while (idx < pReader.getCommentLines().size() && StringUtils.isEmpty(pReader.getCommentLines().get(idx))) {
idx++;
blankLines++;
}
final String comment = extractComment(pReader.getCommentLines(), idx, pReader.getCommentLines().size() - 1);
final PropertyLayoutData data = fetchLayoutData(pReader.getPropertyName());
if (contained) {
data.addComment(comment);
data.setSingleLine(false);
} else {
data.setComment(comment);
data.setBlankLines(blankLines);
data.setSeparator(pReader.getPropertySeparator());
}
}
}
setFooterComment(extractComment(pReader.getCommentLines(), 0, pReader.getCommentLines().size() - 1));
} catch (final IOException ioex) {
throw new ConfigurationException(ioex);
} finally {
loadCounter.decrementAndGet();
}
}
/**
* The event listener callback. Here event notifications of the configuration object are processed to update the layout
* object properly.
*
* @param event the event object
*/
@Override
public void onEvent(final ConfigurationEvent event) {
if (!event.isBeforeUpdate() && loadCounter.get() == 0) {
if (ConfigurationEvent.ADD_PROPERTY.equals(event.getEventType())) {
final boolean contained = layoutData.containsKey(event.getPropertyName());
final PropertyLayoutData data = fetchLayoutData(event.getPropertyName());
data.setSingleLine(!contained);
} else if (ConfigurationEvent.CLEAR_PROPERTY.equals(event.getEventType())) {
layoutData.remove(event.getPropertyName());
} else if (ConfigurationEvent.CLEAR.equals(event.getEventType())) {
clear();
} else if (ConfigurationEvent.SET_PROPERTY.equals(event.getEventType())) {
fetchLayoutData(event.getPropertyName());
}
}
}
/**
* Writes the properties file to the given writer, preserving as much of its structure as possible.
*
* @param config the associated configuration object
* @param writer the writer
* @throws ConfigurationException if an error occurs
*/
public void save(final PropertiesConfiguration config, final Writer writer) throws ConfigurationException {
try {
@SuppressWarnings("resource") // createPropertiesReader wraps the writer.
final PropertiesConfiguration.PropertiesWriter pWriter = config.getIOFactory().createPropertiesWriter(writer, config.getListDelimiterHandler());
pWriter.setGlobalSeparator(getGlobalSeparator());
if (getLineSeparator() != null) {
pWriter.setLineSeparator(getLineSeparator());
}
if (headerComment != null) {
writeComment(pWriter, getCanonicalHeaderComment(true));
}
boolean firstKey = true;
for (final String key : getKeys()) {
if (config.containsKeyInternal(key)) {
// preset header comment needs to be separated from key
if (firstKey && headerComment != null && getBlankLinesBefore(key) == 0) {
pWriter.writeln(null);
}
// Output blank lines before property
for (int i = 0; i < getBlankLinesBefore(key); i++) {
pWriter.writeln(null);
}
// Output the comment
writeComment(pWriter, getCanonicalComment(key, true));
// Output the property and its value
final boolean singleLine = isForceSingleLine() || isSingleLine(key);
pWriter.setCurrentSeparator(getSeparator(key));
pWriter.writeProperty(key, config.getPropertyInternal(key), singleLine);
}
firstKey = false;
}
writeComment(pWriter, getCanonicalFooterCooment(true));
pWriter.flush();
} catch (final IOException ioex) {
throw new ConfigurationException(ioex);
}
}
/**
* Sets the number of blank lines before the given property key. This can be used for a logical grouping of properties.
*
* @param key the property key
* @param number the number of blank lines to add before this property definition
* @deprecated use {@link PropertiesConfigurationLayout#setBlankLinesBefore(String, int)}.
*/
@Deprecated
public void setBlancLinesBefore(final String key, final int number) {
setBlankLinesBefore(key, number);
}
/**
* Sets the number of blank lines before the given property key. This can be used for a logical grouping of properties.
*
* @param key the property key
* @param number the number of blank lines to add before this property definition
* @since 2.8.0
*/
public void setBlankLinesBefore(final String key, final int number) {
fetchLayoutData(key).setBlankLines(number);
}
/**
* Sets the comment for the specified property key. The comment (or its single lines if it is a multi-line comment) can
* start with a comment character. If this is the case, it will be written without changes. Otherwise a default comment
* character is added automatically.
*
* @param key the key of the property
* @param comment the comment for this key (can be <b>null</b>, then the comment will be removed)
*/
public void setComment(final String key, final String comment) {
fetchLayoutData(key).setComment(comment);
}
/**
* Sets the footer comment for the represented properties file. This comment will be output at the bottom of the file.
*
* @param footerComment the footer comment
* @since 2.0
*/
public void setFooterComment(final String footerComment) {
this.footerComment = footerComment;
}
/**
* Sets the "force single line" flag. If this flag is set, all properties with multiple values are written on
* single lines. This mode provides more compatibility with {@link Properties}, which cannot deal with
* multiple definitions of a single property. This mode has no effect if the list delimiter parsing is disabled.
*
* @param f the force single line flag
*/
public void setForceSingleLine(final boolean f) {
forceSingleLine = f;
}
/**
* Sets the global separator for properties. With this method a separator can be set that will be used for all
* properties when writing the configuration. This is an easy way of determining the properties separator globally. To
* be compatible with the properties format only the characters {@code =} and {@code :} (with or without whitespace)
* should be used, but this method does not enforce this - it accepts arbitrary strings. If the global separator is set
* to <b>null</b>, property separators are not changed. This is the default behavior as it produces results that are
* closer to the original properties file.
*
* @param globalSeparator the separator to be used for all properties
* @since 1.7
*/
public void setGlobalSeparator(final String globalSeparator) {
this.globalSeparator = globalSeparator;
}
/**
* Sets the header comment for the represented properties file. This comment will be output on top of the file.
*
* @param comment the comment
*/
public void setHeaderComment(final String comment) {
headerComment = comment;
}
/**
* Sets the line separator. When writing the properties configuration, all lines are terminated with this separator. If
* no separator was set, the platform-specific default line separator is used.
*
* @param lineSeparator the line separator
* @since 1.7
*/
public void setLineSeparator(final String lineSeparator) {
this.lineSeparator = lineSeparator;
}
/**
* Sets the separator to be used for the property with the given key. The separator is the string between the property
* key and its value. For new properties " = " is used. When a properties file is read, the layout tries to
* determine the separator for each property. With this method the separator can be changed. To be compatible with the
* properties format only the characters {@code =} and {@code :} (with or without whitespace) should be used, but this
* method does not enforce this - it accepts arbitrary strings. If the key refers to a property with multiple values
* that are written on multiple lines, this separator will be used on all lines.
*
* @param key the key for the property
* @param sep the separator to be used for this property
* @since 1.7
*/
public void setSeparator(final String key, final String sep) {
fetchLayoutData(key).setSeparator(sep);
}
/**
* Sets the "single line flag" for the specified property key. This flag is evaluated if the property has
* multiple values (i.e. if it is a list property). In this case, if the flag is set, all values will be written in a
* single property definition using the list delimiter as separator. Otherwise multiple lines will be written for this
* property, each line containing one property value.
*
* @param key the property key
* @param f the single line flag
*/
public void setSingleLine(final String key, final boolean f) {
fetchLayoutData(key).setSingleLine(f);
}
}