    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.configuration2;
    018
    019import java.io.BufferedReader;
    020import java.io.IOException;
    021import java.io.PrintWriter;
    022import java.io.Reader;
    023import java.io.Writer;
    024import java.util.ArrayList;
    025import java.util.Collection;
    026import java.util.LinkedHashMap;
    027import java.util.LinkedHashSet;
    028import java.util.List;
    029import java.util.Map;
    030import java.util.Set;
    031
    032import org.apache.commons.configuration2.convert.ListDelimiterHandler;
    033import org.apache.commons.configuration2.ex.ConfigurationException;
    034import org.apache.commons.configuration2.ex.ConfigurationRuntimeException;
    035import org.apache.commons.configuration2.tree.ImmutableNode;
    036import org.apache.commons.configuration2.tree.InMemoryNodeModel;
    037import org.apache.commons.configuration2.tree.InMemoryNodeModelSupport;
    038import org.apache.commons.configuration2.tree.NodeHandler;
    039import org.apache.commons.configuration2.tree.NodeHandlerDecorator;
    040import org.apache.commons.configuration2.tree.NodeSelector;
    041import org.apache.commons.configuration2.tree.TrackedNodeModel;
    042
    043/**
    044 * <p>
    045 * A specialized hierarchical configuration implementation for parsing ini
    046 * files.
    047 * </p>
    048 * <p>
    049 * An initialization or ini file is a configuration file typically found on
    050 * Microsoft's Windows operating system and contains data for Windows based
    051 * applications.
    052 * </p>
    053 * <p>
    054 * Although popularized by Windows, ini files can be used on any system or
    055 * platform due to the fact that they are merely text files that can easily be
    056 * parsed and modified by both humans and computers.
    057 * </p>
    058 * <p>
    059 * A typical ini file could look something like:
    060 * </p>
    061 * <pre>
    062 * [section1]
    063 * ; this is a comment!
    064 * var1 = foo
    065 * var2 = bar
    066 *
    067 * [section2]
    068 * var1 = doo
    069 * </pre>
    070 * <p>
    071 * The format of ini files is fairly straight forward and is composed of three
    072 * components:</p>
    073 * <ul>
    074 * <li><b>Sections:</b> Ini files are split into sections, each section starting
    075 * with a section declaration. A section declaration starts with a '[' and ends
    076 * with a ']'. Sections occur on one line only.</li>
    077 * <li><b>Parameters:</b> Items in a section are known as parameters. Parameters
    078 * have a typical {@code key = value} format.</li>
    079 * <li><b>Comments:</b> Lines starting with a ';' are assumed to be comments.</li>
    080 * </ul>
    081 * <p>
    082 * There are various implementations of the ini file format by various vendors
    083 * which has caused a number of differences to appear. As far as possible this
    084 * configuration tries to be lenient and support most of the differences.
    085 * </p>
    086 * <p>
    087 * Some of the differences supported are as follows:
    088 * </p>
    089 * <ul>
    090 * <li><b>Comments:</b> The '#' character is also accepted as a comment
    091 * signifier.</li>
    092 * <li><b>Key value separator:</b> The ':' character is also accepted in place of
    093 * '=' to separate keys and values in parameters, for example
    094 * {@code var1 : foo}.</li>
    095 * <li><b>Duplicate sections:</b> Typically duplicate sections are not allowed,
    096 * this configuration does however support this feature. In the event of a duplicate
    097 * section, the two section's values are merged so that there is only a single
    098 * section. <strong>Note</strong>: This also affects the internal data of the
    099 * configuration. If it is saved, only a single section is written!</li>
    100 * <li><b>Duplicate parameters:</b> Typically duplicate parameters are only
    101 * allowed if they are in two different sections, thus they are local to
    102 * sections; this configuration simply merges duplicates; if a section has a
    103 * duplicate parameter the values are then added to the key as a list.</li>
    104 * </ul>
    105 * <p>
    106 * Global parameters are also allowed; any parameters declared before a section
    107 * is declared are added to a global section. It is important to note that this
    108 * global section does not have a name.
    109 * </p>
    110 * <p>
    111 * In all instances, a parameter's key is prepended with its section name and a
    112 * '.' (period). Thus a parameter named "var1" in "section1" will have the key
    113 * {@code section1.var1} in this configuration. (This is the default
    114 * behavior. Because this is a hierarchical configuration you can change this by
    115 * setting a different {@link org.apache.commons.configuration2.tree.ExpressionEngine}.)
    116 * </p>
    117 * <h3>Implementation Details:</h3> Consider the following ini file:
    118 * <pre>
    119 *  default = ok
    120 *
    121 *  [section1]
    122 *  var1 = foo
    123 *  var2 = doodle
    124 *
    125 *  [section2]
    126 *  ; a comment
    127 *  var1 = baz
    128 *  var2 = shoodle
    129 *  bad =
    130 *  = worse
    131 *
    132 *  [section3]
    133 *  # another comment
    134 *  var1 : foo
    135 *  var2 : bar
    136 *  var5 : test1
    137 *
    138 *  [section3]
    139 *  var3 = foo
    140 *  var4 = bar
    141 *  var5 = test2
    142 *
    143 *  [sectionSeparators]
    144 *  passwd : abc=def
    145 *  a:b = "value"
    146 *  </pre>
    147 * <p>
    148 * This ini file will be parsed without error. Note:</p>
    149 * <ul>
    150 * <li>The parameter named "default" is added to the global section, it's value
    151 * is accessed simply using {@code getProperty("default")}.</li>
    152 * <li>Section 1's parameters can be accessed using
    153 * {@code getProperty("section1.var1")}.</li>
    154 * <li>The parameter named "bad" simply adds the parameter with an empty value.</li>
    155 * <li>The empty key with value "= worse" is added using a key consisting of a
    156 * single space character. This key is still added to section 2 and the value
    157 * can be accessed using {@code getProperty("section2. ")}, notice the
    158 * period '.' and the space following the section name.</li>
    159 * <li>Section three uses both '=' and ':' to separate keys and values.</li>
    160 * <li>Section 3 has a duplicate key named "var5". The value for this key is
    161 * [test1, test2], and is represented as a List.</li>
    162 * <li>The section called <em>sectionSeparators</em> demonstrates how the
    163 * configuration deals with multiple occurrences of separator characters. Per
    164 * default the first separator character in a line is detected and used to
    165 * split the key from the value. Therefore the first property definition in this
    166 * section has the key {@code passwd} and the value {@code abc=def}.
    167 * This default behavior can be changed by using quotes. If there is a separator
    168 * character before the first quote character (ignoring whitespace), this
    169 * character is used as separator. Thus the second property definition in the
    170 * section has the key {@code a:b} and the value {@code value}.</li>
    171 * </ul>
    172 * <p>
    173 * Internally, this configuration maps the content of the represented ini file
    174 * to its node structure in the following way:</p>
    175 * <ul>
    176 * <li>Sections are represented by direct child nodes of the root node.</li>
    177 * <li>For the content of a section, corresponding nodes are created as children
    178 * of the section node.</li>
    179 * </ul>
    180 * <p>
    181 * This explains how the keys for the properties can be constructed. You can
    182 * also use other methods of {@link HierarchicalConfiguration} for querying or
    183 * manipulating the hierarchy of configuration nodes, for instance the
    184 * {@code configurationAt()} method for obtaining the data of a specific
    185 * section. However, be careful that the storage scheme described above is not
    186 * violated (e.g. by adding multiple levels of nodes or inserting duplicate
    187 * section nodes). Otherwise, the special methods for ini configurations may not
    188 * work correctly!
    189 * </p>
    190 * <p>
    191 * The set of sections in this configuration can be retrieved using the
    192 * {@code getSections()} method. For obtaining a
    193 * {@code SubnodeConfiguration} with the content of a specific section the
    194 * {@code getSection()} method can be used.
    195 * </p>
    196 * <p>
    197 * Like other {@code Configuration} implementations, this class uses a
    198 * {@code Synchronizer} object to control concurrent access. By choosing a
    199 * suitable implementation of the {@code Synchronizer} interface, an instance
    200 * can be made thread-safe or not. Note that access to most of the properties
    201 * typically set through a builder is not protected by the {@code Synchronizer}.
    202 * The intended usage is that these properties are set once at construction
    203 * time through the builder and after that remain constant. If you wish to
    204 * change such properties during life time of an instance, you have to use
    205 * the {@code lock()} and {@code unlock()} methods manually to ensure that
    206 * other threads see your changes.
    207 * </p>
    208 * <p>
    209 * As this class extends {@link AbstractConfiguration}, all basic features
    210 * like variable interpolation, list handling, or data type conversions are
    211 * available as well. This is described in the chapter
    212 * <a href="http://commons.apache.org/proper/commons-configuration/userguide/howto_basicfeatures.html">
    213 * Basic features and AbstractConfiguration</a> of the user's guide.
    214 * </p>
    215 * <p>
    216 * Note that this configuration does not support properties with null values.
    217 * Such properties are considered to be section nodes.
    218 * </p>
    219 *
    220 * @author <a
    221 *         href="http://commons.apache.org/configuration/team-list.html">Commons
    222 *         Configuration team</a>
    223 * @since 1.6
    224 */
    225public class INIConfiguration extends BaseHierarchicalConfiguration implements
    226        FileBasedConfiguration
    227{
    228    /**
    229     * The default characters that signal the start of a comment line.
    230     */
    231    protected static final String COMMENT_CHARS = "#;";
    232
    233    /**
    234     * The default characters used to separate keys from values.
    235     */
    236    protected static final String SEPARATOR_CHARS = "=:";
    237
    238    /**
    239     * Constant for the line separator.
    240     */
    241    private static final String LINE_SEPARATOR = System.getProperty("line.separator");
    242
    243    /**
    244     * The characters used for quoting values.
    245     */
    246    private static final String QUOTE_CHARACTERS = "\"'";
    247
    248    /**
    249     * The line continuation character.
    250     */
    251    private static final String LINE_CONT = "\\";
    252
    253    /**
    254     * The separator used when writing an INI file.
    255     */
    256    private String separatorUsedInOutput = " = ";
    257
    258    /**
    259     * The separator used when reading an INI file.
    260     */
    261    private String separatorUsedInInput = SEPARATOR_CHARS;
    262
    263    /**
    264     * The characters used to separate keys from values
    265     * when reading an INI file.
    266     */
    267    private String commentCharsUsedInInput = COMMENT_CHARS;
    268
    269    /**
    270     * Create a new empty INI Configuration.
    271     */
    272    public INIConfiguration()
    273    {
    274        super();
    275    }
    276
    277    /**
    278     * Creates a new instance of {@code INIConfiguration} with the
    279     * content of the specified {@code HierarchicalConfiguration}.
    280     *
    281     * @param c the configuration to be copied
    282     * @since 2.0
    283     */
    284    public INIConfiguration(final HierarchicalConfiguration<ImmutableNode> c)
    285    {
    286        super(c);
    287    }
    288
    289    /**
    290     * Get separator used in INI output. see {@code setSeparatorUsedInOutput}
    291     * for further explanation
    292     *
    293     * @return the current separator for writing the INI output
    294     * @since 2.2
    295     */
    296    public String getSeparatorUsedInOutput()
    297    {
    298        beginRead(false);
    299        try
    300        {
    301            return separatorUsedInOutput;
    302        }
    303        finally
    304        {
    305            endRead();
    306        }
    307    }
    308
    309    /**
    310     * Allows setting the key and value separator which is used for the creation
    311     * of the resulting INI output
    312     *
    313     * @param separator String of the new separator for INI output
    314     * @since 2.2
    315     */
    316    public void setSeparatorUsedInOutput(final String separator)
    317    {
    318        beginWrite(false);
    319        try
    320        {
    321            this.separatorUsedInOutput = separator;
    322        }
    323        finally
    324        {
    325            endWrite();
    326        }
    327    }
    328
    329    /**
    330     * Get separator used in INI reading. see {@code setSeparatorUsedInInput}
    331     * for further explanation
    332     *
    333     * @return the current separator for reading the INI input
    334     * @since 2.5
    335     */
    336    public String getSeparatorUsedInInput()
    337    {
    338        beginRead(false);
    339        try
    340        {
    341            return separatorUsedInInput;
    342        }
    343        finally
    344        {
    345            endRead();
    346        }
    347    }
    348
    349    /**
    350     * Allows setting the key and value separator which is used in reading
    351     * an INI file
    352     *
    353     * @param separator String of the new separator for INI reading
    354     * @since 2.5
    355     */
    356    public void setSeparatorUsedInInput(final String separator)
    357    {
    358        beginRead(false);
    359        try
    360        {
    361            this.separatorUsedInInput = separator;
    362        }
    363        finally
    364        {
    365            endRead();
    366        }
    367    }
    368
    369    /**
    370     * Get comment leading separator used in INI reading.
    371     * see {@code setCommentLeadingCharsUsedInInput} for further explanation
    372     *
    373     * @return the current separator for reading the INI input
    374     * @since 2.5
    375     */
    376    public String getCommentLeadingCharsUsedInInput()
    377    {
    378        beginRead(false);
    379        try
    380        {
    381            return commentCharsUsedInInput;
    382        }
    383        finally
    384        {
    385            endRead();
    386        }
    387    }
    388
    389    /**
    390     * Allows setting the leading comment separator which is used in reading
    391     * an INI file
    392     *
    393     * @param separator String of the new separator for INI reading
    394     * @since 2.5
    395     */
    396    public void setCommentLeadingCharsUsedInInput(final String separator)
    397    {
    398        beginRead(false);
    399        try
    400        {
    401            this.commentCharsUsedInInput = separator;
    402        }
    403        finally
    404        {
    405            endRead();
    406        }
    407    }
    408
    409    /**
    410     * Save the configuration to the specified writer.
    411     *
    412     * @param writer - The writer to save the configuration to.
    413     * @throws ConfigurationException If an error occurs while writing the
    414     *         configuration
    415     * @throws IOException if an I/O error occurs
    416     */
    417    @Override
    418    public void write(final Writer writer) throws ConfigurationException, IOException
    419    {
    420        final PrintWriter out = new PrintWriter(writer);
    421        boolean first = true;
    422        final String separator = getSeparatorUsedInOutput();
    423
    424        beginRead(false);
    425        try
    426        {
    427            for (final ImmutableNode node : getModel().getNodeHandler().getRootNode()
    428                    .getChildren())
    429            {
    430                if (isSectionNode(node))
    431                {
    432                    if (!first)
    433                    {
    434                        out.println();
    435                    }
    436                    out.print("[");
    437                    out.print(node.getNodeName());
    438                    out.print("]");
    439                    out.println();
    440
    441                    for (final ImmutableNode child : node.getChildren())
    442                    {
    443                        writeProperty(out, child.getNodeName(),
    444                                child.getValue(), separator);
    445                    }
    446                }
    447                else
    448                {
    449                    writeProperty(out, node.getNodeName(), node.getValue(), separator);
    450                }
    451                first = false;
    452            }
    453            out.println();
    454            out.flush();
    455        }
    456        finally
    457        {
    458            endRead();
    459        }
    460    }
    461
    462    /**
    463     * Load the configuration from the given reader. Note that the
    464     * {@code clear()} method is not called so the configuration read in will
    465     * be merged with the current configuration.
    466     *
    467     * @param in the reader to read the configuration from.
    468     * @throws ConfigurationException If an error occurs while reading the
    469     *         configuration
    470     * @throws IOException if an I/O error occurs
    471     */
    472    @Override
    473    public void read(final Reader in) throws ConfigurationException, IOException
    474    {
    475        final BufferedReader bufferedReader = new BufferedReader(in);
    476        final Map<String, ImmutableNode.Builder> sectionBuilders = new LinkedHashMap<>();
    477        final ImmutableNode.Builder rootBuilder = new ImmutableNode.Builder();
    478
    479        createNodeBuilders(bufferedReader, rootBuilder, sectionBuilders);
    480        final ImmutableNode rootNode = createNewRootNode(rootBuilder, sectionBuilders);
    481        addNodes(null, rootNode.getChildren());
    482    }
    483
    484    /**
    485     * Creates a new root node from the builders constructed while reading the
    486     * configuration file.
    487     *
    488     * @param rootBuilder the builder for the top-level section
    489     * @param sectionBuilders a map storing the section builders
    490     * @return the root node of the newly created hierarchy
    491     */
    492    private static ImmutableNode createNewRootNode(
    493            final ImmutableNode.Builder rootBuilder,
    494            final Map<String, ImmutableNode.Builder> sectionBuilders)
    495    {
    496        for (final Map.Entry<String, ImmutableNode.Builder> e : sectionBuilders
    497                .entrySet())
    498        {
    499            rootBuilder.addChild(e.getValue().name(e.getKey()).create());
    500        }
    501        return rootBuilder.create();
    502    }
    503
    504    /**
    505     * Reads the content of an INI file from the passed in reader and creates a
    506     * structure of builders for constructing the {@code ImmutableNode} objects
    507     * representing the data.
    508     *
    509     * @param in the reader
    510     * @param rootBuilder the builder for the top-level section
    511     * @param sectionBuilders a map storing the section builders
    512     * @throws IOException if an I/O error occurs
    513     */
    514    private void createNodeBuilders(final BufferedReader in,
    515            final ImmutableNode.Builder rootBuilder,
    516            final Map<String, ImmutableNode.Builder> sectionBuilders)
    517            throws IOException
    518    {
    519        ImmutableNode.Builder sectionBuilder = rootBuilder;
    520        String line = in.readLine();
    521        while (line != null)
    522        {
    523            line = line.trim();
    524            if (!isCommentLine(line))
    525            {
    526                if (isSectionLine(line))
    527                {
    528                    final String section = line.substring(1, line.length() - 1);
    529                    sectionBuilder = sectionBuilders.get(section);
    530                    if (sectionBuilder == null)
    531                    {
    532                        sectionBuilder = new ImmutableNode.Builder();
    533                        sectionBuilders.put(section, sectionBuilder);
    534                    }
    535                }
    536
    537                else
    538                {
    539                    String key;
    540                    String value = "";
    541                    final int index = findSeparator(line);
    542                    if (index >= 0)
    543                    {
    544                        key = line.substring(0, index);
    545                        value = parseValue(line.substring(index + 1), in);
    546                    }
    547                    else
    548                    {
    549                        key = line;
    550                    }
    551                    key = key.trim();
    552                    if (key.length() < 1)
    553                    {
    554                        // use space for properties with no key
    555                        key = " ";
    556                    }
    557                    createValueNodes(sectionBuilder, key, value);
    558                }
    559            }
    560
    561            line = in.readLine();
    562        }
    563    }
    564
    565    /**
    566     * Creates the node(s) for the given key value-pair. If delimiter parsing is
    567     * enabled, the value string is split if possible, and for each single value
    568     * a node is created. Otherwise only a single node is added to the section.
    569     *
    570     * @param sectionBuilder the section builder for adding new nodes
    571     * @param key the key
    572     * @param value the value string
    573     */
    574    private void createValueNodes(final ImmutableNode.Builder sectionBuilder,
    575            final String key, final String value)
    576    {
    577        final Collection<String> values =
    578                getListDelimiterHandler().split(value, false);
    579
    580        for (final String v : values)
    581        {
    582            sectionBuilder.addChild(new ImmutableNode.Builder().name(key)
    583                    .value(v).create());
    584        }
    585    }
    586
    587    /**
    588     * Writes data about a property into the given stream.
    589     *
    590     * @param out the output stream
    591     * @param key the key
    592     * @param value the value
    593     */
    594    private void writeProperty(final PrintWriter out, final String key, final Object value, final String separator)
    595    {
    596        out.print(key);
    597        out.print(separator);
    598        out.print(escapeValue(value.toString()));
    599        out.println();
    600    }
    601
    602    /**
    603     * Parse the value to remove the quotes and ignoring the comment. Example:
    604     *
    605     * <pre>
    606     * &quot;value&quot; ; comment -&gt; value
    607     * </pre>
    608     *
    609     * <pre>
    610     * 'value' ; comment -&gt; value
    611     * </pre>
    612     * Note that a comment character is only recognized if there is at least one
    613     * whitespace character before it. So it can appear in the property value,
    614     * e.g.:
    615     * <pre>
    616     * C:\\Windows;C:\\Windows\\system32
    617     * </pre>
    618     *
    619     * @param val the value to be parsed
    620     * @param reader the reader (needed if multiple lines have to be read)
    621     * @throws IOException if an IO error occurs
    622     */
    623    private String parseValue(final String val, final BufferedReader reader)
    624        throws IOException
    625    {
    626        final StringBuilder propertyValue = new StringBuilder();
    627        boolean lineContinues;
    628        String value = val.trim();
    629
    630        do
    631        {
    632            final boolean quoted = value.startsWith("\"") || value.startsWith("'");
    633            boolean stop = false;
    634            boolean escape = false;
    635
    636            final char quote = quoted ? value.charAt(0) : 0;
    637
    638            int i = quoted ? 1 : 0;
    639
    640            final StringBuilder result = new StringBuilder();
    641            char lastChar = 0;
    642            while (i < value.length() && !stop)
    643            {
    644                final char c = value.charAt(i);
    645
    646                if (quoted)
    647                {
    648                    if ('\\' == c && !escape)
    649                    {
    650                        escape = true;
    651                    }
    652                    else if (!escape && quote == c)
    653                    {
    654                        stop = true;
    655                    }
    656                    else if (escape && quote == c)
    657                    {
    658                        escape = false;
    659                        result.append(c);
    660                    }
    661                    else
    662                    {
    663                        if (escape)
    664                        {
    665                            escape = false;
    666                            result.append('\\');
    667                        }
    668
    669                        result.append(c);
    670                    }
    671                }
    672                else
    673                {
    674                    if (isCommentChar(c) && Character.isWhitespace(lastChar))
    675                    {
    676                        stop = true;
    677                    }
    678                    else
    679                    {
    680                        result.append(c);
    681                    }
    682                }
    683
    684                i++;
    685                lastChar = c;
    686            }
    687
    688            String v = result.toString();
    689            if (!quoted)
    690            {
    691                v = v.trim();
    692                lineContinues = lineContinues(v);
    693                if (lineContinues)
    694                {
    695                    // remove trailing "\"
    696                    v = v.substring(0, v.length() - 1).trim();
    697                }
    698            }
    699            else
    700            {
    701                lineContinues = lineContinues(value, i);
    702            }
    703            propertyValue.append(v);
    704
    705            if (lineContinues)
    706            {
    707                propertyValue.append(LINE_SEPARATOR);
    708                value = reader.readLine();
    709            }
    710        } while (lineContinues && value != null);
    711
    712        return propertyValue.toString();
    713    }
    714
    715    /**
    716     * Tests whether the specified string contains a line continuation marker.
    717     *
    718     * @param line the string to check
    719     * @return a flag whether this line continues
    720     */
    721    private static boolean lineContinues(final String line)
    722    {
    723        final String s = line.trim();
    724        return s.equals(LINE_CONT)
    725                || (s.length() > 2 && s.endsWith(LINE_CONT) && Character
    726                        .isWhitespace(s.charAt(s.length() - 2)));
    727    }
    728
    729    /**
    730     * Tests whether the specified string contains a line continuation marker
    731     * after the specified position. This method parses the string to remove a
    732     * comment that might be present. Then it checks whether a line continuation
    733     * marker can be found at the end.
    734     *
    735     * @param line the line to check
    736     * @param pos the start position
    737     * @return a flag whether this line continues
    738     */
    739    private boolean lineContinues(final String line, final int pos)
    740    {
    741        String s;
    742
    743        if (pos >= line.length())
    744        {
    745            s = line;
    746        }
    747        else
    748        {
    749            int end = pos;
    750            while (end < line.length() && !isCommentChar(line.charAt(end)))
    751            {
    752                end++;
    753            }
    754            s = line.substring(pos, end);
    755        }
    756
    757        return lineContinues(s);
    758    }
    759
    760    /**
    761     * Tests whether the specified character is a comment character.
    762     *
    763     * @param c the character
    764     * @return a flag whether this character starts a comment
    765     */
    766    private boolean isCommentChar(final char c)
    767    {
    768        return getCommentLeadingCharsUsedInInput().indexOf(c) >= 0;
    769    }
    770
    771    /**
    772     * Tries to find the index of the separator character in the given string.
    773     * This method checks for the presence of separator characters in the given
    774     * string. If multiple characters are found, the first one is assumed to be
    775     * the correct separator. If there are quoting characters, they are taken
    776     * into account, too.
    777     *
    778     * @param line the line to be checked
    779     * @return the index of the separator character or -1 if none is found
    780     */
    781    private int findSeparator(final String line)
    782    {
    783        int index =
    784                findSeparatorBeforeQuote(line,
    785                        findFirstOccurrence(line, QUOTE_CHARACTERS));
    786        if (index < 0)
    787        {
    788            index = findFirstOccurrence(line, getSeparatorUsedInInput());
    789        }
    790        return index;
    791    }
    792
    793    /**
    794     * Checks for the occurrence of the specified separators in the given line.
    795     * The index of the first separator is returned.
    796     *
    797     * @param line the line to be investigated
    798     * @param separators a string with the separator characters to look for
    799     * @return the lowest index of a separator character or -1 if no separator
    800     *         is found
    801     */
    802    private static int findFirstOccurrence(final String line, final String separators)
    803    {
    804        int index = -1;
    805
    806        for (int i = 0; i < separators.length(); i++)
    807        {
    808            final char sep = separators.charAt(i);
    809            final int pos = line.indexOf(sep);
    810            if (pos >= 0)
    811            {
    812                if (index < 0 || pos < index)
    813                {
    814                    index = pos;
    815                }
    816            }
    817        }
    818
    819        return index;
    820    }
    821
    822    /**
    823     * Searches for a separator character directly before a quoting character.
    824     * If the first non-whitespace character before a quote character is a
    825     * separator, it is considered the "real" separator in this line - even if
    826     * there are other separators before.
    827     *
    828     * @param line the line to be investigated
    829     * @param quoteIndex the index of the quote character
    830     * @return the index of the separator before the quote or &lt; 0 if there is
    831     *         none
    832     */
    833    private static int findSeparatorBeforeQuote(final String line, final int quoteIndex)
    834    {
    835        int index = quoteIndex - 1;
    836        while (index >= 0 && Character.isWhitespace(line.charAt(index)))
    837        {
    838            index--;
    839        }
    840
    841        if (index >= 0 && SEPARATOR_CHARS.indexOf(line.charAt(index)) < 0)
    842        {
    843            index = -1;
    844        }
    845
    846        return index;
    847    }
    848
    849    /**
    850     * Escapes the given property value before it is written. This method add
    851     * quotes around the specified value if it contains a comment character and
    852     * handles list delimiter characters.
    853     *
    854     * @param value the string to be escaped
    855     */
    856    private String escapeValue(final String value)
    857    {
    858        return String.valueOf(getListDelimiterHandler().escape(
    859                escapeComments(value), ListDelimiterHandler.NOOP_TRANSFORMER));
    860    }
    861
    862    /**
    863     * Escapes comment characters in the given value.
    864     *
    865     * @param value the value to be escaped
    866     * @return the value with comment characters escaped
    867     */
    868    private String escapeComments(final String value)
    869    {
    870        final String commentChars = getCommentLeadingCharsUsedInInput();
    871        boolean quoted = false;
    872
    873        for (int i = 0; i < commentChars.length() && !quoted; i++)
    874        {
    875            final char c = commentChars.charAt(i);
    876            if (value.indexOf(c) != -1)
    877            {
    878                quoted = true;
    879            }
    880        }
    881
    882        if (quoted)
    883        {
    884            return '"' + value.replaceAll("\"", "\\\\\\\"") + '"';
    885        }
    886        return value;
    887    }
    888
    889    /**
    890     * Determine if the given line is a comment line.
    891     *
    892     * @param line The line to check.
    893     * @return true if the line is empty or starts with one of the comment
    894     *         characters
    895     */
    896    protected boolean isCommentLine(final String line)
    897    {
    898        if (line == null)
    899        {
    900            return false;
    901        }
    902        // blank lines are also treated as comment lines
    903        return line.length() < 1
    904            || getCommentLeadingCharsUsedInInput().indexOf(line.charAt(0)) >= 0;
    905    }
    906
    907    /**
    908     * Determine if the given line is a section.
    909     *
    910     * @param line The line to check.
    911     * @return true if the line contains a section
    912     */
    913    protected boolean isSectionLine(final String line)
    914    {
    915        if (line == null)
    916        {
    917            return false;
    918        }
    919        return line.startsWith("[") && line.endsWith("]");
    920    }
    921
    922    /**
    923     * Return a set containing the sections in this ini configuration. Note that
    924     * changes to this set do not affect the configuration.
    925     *
    926     * @return a set containing the sections.
    927     */
    928    public Set<String> getSections()
    929    {
    930        final Set<String> sections = new LinkedHashSet<>();
    931        boolean globalSection = false;
    932        boolean inSection = false;
    933
    934        beginRead(false);
    935        try
    936        {
    937            for (final ImmutableNode node : getModel().getNodeHandler().getRootNode()
    938                    .getChildren())
    939            {
    940                if (isSectionNode(node))
    941                {
    942                    inSection = true;
    943                    sections.add(node.getNodeName());
    944                }
    945                else
    946                {
    947                    if (!inSection && !globalSection)
    948                    {
    949                        globalSection = true;
    950                        sections.add(null);
    951                    }
    952                }
    953            }
    954        }
    955        finally
    956        {
    957            endRead();
    958        }
    959
    960        return sections;
    961    }
    962
    963    /**
    964     * Returns a configuration with the content of the specified section. This
    965     * provides an easy way of working with a single section only. The way this
    966     * configuration is structured internally, this method is very similar to
    967     * calling {@link HierarchicalConfiguration#configurationAt(String)} with
    968     * the name of the section in question. There are the following differences
    969     * however:
    970     * <ul>
    971     * <li>This method never throws an exception. If the section does not exist,
    972     * it is created now. The configuration returned in this case is empty.</li>
    973     * <li>If section is contained multiple times in the configuration, the
    974     * configuration returned by this method is initialized with the first
    975     * occurrence of the section. (This can only happen if
    976     * {@code addProperty()} has been used in a way that does not conform
    977     * to the storage scheme used by {@code INIConfiguration}.
    978     * If used correctly, there will not be duplicate sections.)</li>
    979     * <li>There is special support for the global section: Passing in
    980     * <b>null</b> as section name returns a configuration with the content of
    981     * the global section (which may also be empty).</li>
    982     * </ul>
    983     *
    984     * @param name the name of the section in question; <b>null</b> represents
    985     *        the global section
    986     * @return a configuration containing only the properties of the specified
    987     *         section
    988     */
    989    public SubnodeConfiguration getSection(final String name)
    990    {
    991        if (name == null)
    992        {
    993            return getGlobalSection();
    994        }
    995        try
    996        {
    997            return (SubnodeConfiguration) configurationAt(name, true);
    998        }
    999        catch (final ConfigurationRuntimeException iex)
    1000        {
    1001            // the passed in key does not map to exactly one node
    1002            // obtain the node for the section, create it on demand
    1003            final InMemoryNodeModel parentModel = getSubConfigurationParentModel();
    1004            final NodeSelector selector = parentModel.trackChildNodeWithCreation(null, name, this);
    1005            return createSubConfigurationForTrackedNode(selector, this);
    1006        }
    1007    }
    1008
    1009    /**
    1010     * Creates a sub configuration for the global section of the represented INI
    1011     * configuration.
    1012     *
    1013     * @return the sub configuration for the global section
    1014     */
    1015    private SubnodeConfiguration getGlobalSection()
    1016    {
    1017        final InMemoryNodeModel parentModel = getSubConfigurationParentModel();
    1018        final NodeSelector selector = new NodeSelector(null); // selects parent
    1019        parentModel.trackNode(selector, this);
    1020        final GlobalSectionNodeModel model =
    1021                new GlobalSectionNodeModel(this, selector);
    1022        final SubnodeConfiguration sub = new SubnodeConfiguration(this, model);
    1023        initSubConfigurationForThisParent(sub);
    1024        return sub;
    1025    }
    1026
    1027    /**
    1028     * Checks whether the specified configuration node represents a section.
    1029     *
    1030     * @param node the node in question
    1031     * @return a flag whether this node represents a section
    1032     */
    1033    private static boolean isSectionNode(final ImmutableNode node)
    1034    {
    1035        return node.getValue() == null;
    1036    }
    1037
    1038    /**
    1039     * A specialized node model implementation for the sub configuration
    1040     * representing the global section of the INI file. This is a regular
    1041     * {@code TrackedNodeModel} with one exception: The {@code NodeHandler} used
    1042     * by this model applies a filter on the children of the root node so that
    1043     * only nodes are visible that are no sub sections.
    1044     */
    1045    private static class GlobalSectionNodeModel extends TrackedNodeModel
    1046    {
    1047        /**
    1048         * Creates a new instance of {@code GlobalSectionNodeModel} and
    1049         * initializes it with the given underlying model.
    1050         *
    1051         * @param modelSupport the underlying {@code InMemoryNodeModel}
    1052         * @param selector the {@code NodeSelector}
    1053         */
    1054        public GlobalSectionNodeModel(final InMemoryNodeModelSupport modelSupport,
    1055                final NodeSelector selector)
    1056        {
    1057            super(modelSupport, selector, true);
    1058        }
    1059
    1060        @Override
    1061        public NodeHandler<ImmutableNode> getNodeHandler()
    1062        {
    1063            return new NodeHandlerDecorator<ImmutableNode>()
    1064            {
    1065                @Override
    1066                public List<ImmutableNode> getChildren(final ImmutableNode node)
    1067                {
    1068                    final List<ImmutableNode> children = super.getChildren(node);
    1069                    return filterChildrenOfGlobalSection(node, children);
    1070                }
    1071
    1072                @Override
    1073                public List<ImmutableNode> getChildren(final ImmutableNode node,
    1074                        final String name)
    1075                {
    1076                    final List<ImmutableNode> children =
    1077                            super.getChildren(node, name);
    1078                    return filterChildrenOfGlobalSection(node, children);
    1079                }
    1080
    1081                @Override
    1082                public int getChildrenCount(final ImmutableNode node, final String name)
    1083                {
    1084                    final List<ImmutableNode> children =
    1085                            (name != null) ? super.getChildren(node, name)
    1086                                    : super.getChildren(node);
    1087                    return filterChildrenOfGlobalSection(node, children).size();
    1088                }
    1089
    1090                @Override
    1091                public ImmutableNode getChild(final ImmutableNode node, final int index)
    1092                {
    1093                    final List<ImmutableNode> children = super.getChildren(node);
    1094                    return filterChildrenOfGlobalSection(node, children).get(
    1095                            index);
    1096                }
    1097
    1098                @Override
    1099                public int indexOfChild(final ImmutableNode parent,
    1100                        final ImmutableNode child)
    1101                {
    1102                    final List<ImmutableNode> children = super.getChildren(parent);
    1103                    return filterChildrenOfGlobalSection(parent, children)
    1104                            .indexOf(child);
    1105                }
    1106
    1107                @Override
    1108                protected NodeHandler<ImmutableNode> getDecoratedNodeHandler()
    1109                {
    1110                    return GlobalSectionNodeModel.super.getNodeHandler();
    1111                }
    1112
    1113                /**
    1114                 * Filters the child nodes of the global section. This method
    1115                 * checks whether the passed in node is the root node of the
    1116                 * configuration. If so, from the list of children all nodes are
    1117                 * filtered which are section nodes.
    1118                 *
    1119                 * @param node the node in question
    1120                 * @param children the children of this node
    1121                 * @return a list with the filtered children
    1122                 */
    1123                private List<ImmutableNode> filterChildrenOfGlobalSection(
    1124                        final ImmutableNode node, final List<ImmutableNode> children)
    1125                {
    1126                    List<ImmutableNode> filteredList;
    1127                    if (node == getRootNode())
    1128                    {
    1129                        filteredList =
    1130                                new ArrayList<>(children.size());
    1131                        for (final ImmutableNode child : children)
    1132                        {
    1133                            if (!isSectionNode(child))
    1134                            {
    1135                                filteredList.add(child);
    1136                            }
    1137                        }
    1138                    }
    1139                    else
    1140                    {
    1141                        filteredList = children;
    1142                    }
    1143
    1144                    return filteredList;
    1145                }
    1146            };
    1147        }
    1148    }
    1149}