    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.lang3.text;
    018
    019import java.util.ArrayList;
    020import java.util.Enumeration;
    021import java.util.HashMap;
    022import java.util.List;
    023import java.util.Map;
    024import java.util.Properties;
    025
    026import org.apache.commons.lang3.StringUtils;
    027
    028/**
    029 * Substitutes variables within a string by values.
    030 * <p>
    031 * This class takes a piece of text and substitutes all the variables within it.
    032 * The default definition of a variable is {@code ${variableName}}.
    033 * The prefix and suffix can be changed via constructors and set methods.
    034 * <p>
    035 * Variable values are typically resolved from a map, but could also be resolved
    036 * from system properties, or by supplying a custom variable resolver.
    037 * <p>
    038 * The simplest example is to use this class to replace Java System properties. For example:
    039 * <pre>
    040 * StrSubstitutor.replaceSystemProperties(
    041 *      "You are running with java.version = ${java.version} and os.name = ${os.name}.");
    042 * </pre>
    043 * <p>
    044 * Typical usage of this class follows the following pattern: First an instance is created
    045 * and initialized with the map that contains the values for the available variables.
    046 * If a prefix and/or suffix for variables should be used other than the default ones,
    047 * the appropriate settings can be performed. After that the {@code replace()}
    048 * method can be called passing in the source text for interpolation. In the returned
    049 * text all variable references (as long as their values are known) will be resolved.
    050 * The following example demonstrates this:
    051 * <pre>
    052 * Map valuesMap = HashMap();
    053 * valuesMap.put(&quot;animal&quot;, &quot;quick brown fox&quot;);
    054 * valuesMap.put(&quot;target&quot;, &quot;lazy dog&quot;);
    055 * String templateString = &quot;The ${animal} jumps over the ${target}.&quot;;
    056 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
    057 * String resolvedString = sub.replace(templateString);
    058 * </pre>
    059 * yielding:
    060 * <pre>
    061 *      The quick brown fox jumps over the lazy dog.
    062 * </pre>
    063 * <p>
    064 * Also, this class allows to set a default value for unresolved variables.
    065 * The default value for a variable can be appended to the variable name after the variable
    066 * default value delimiter. The default value of the variable default value delimiter is ':-',
    067 * as in bash and other *nix shells, as those are arguably where the default ${} delimiter set originated.
    068 * The variable default value delimiter can be manually set by calling {@link #setValueDelimiterMatcher(StrMatcher)},
    069 * {@link #setValueDelimiter(char)} or {@link #setValueDelimiter(String)}.
    070 * The following shows an example with variable default value settings:
    071 * <pre>
    072 * Map valuesMap = HashMap();
    073 * valuesMap.put(&quot;animal&quot;, &quot;quick brown fox&quot;);
    074 * valuesMap.put(&quot;target&quot;, &quot;lazy dog&quot;);
    075 * String templateString = &quot;The ${animal} jumps over the ${target}. ${undefined.number:-1234567890}.&quot;;
    076 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
    077 * String resolvedString = sub.replace(templateString);
    078 * </pre>
    079 * yielding:
    080 * <pre>
    081 *      The quick brown fox jumps over the lazy dog. 1234567890.
    082 * </pre>
    083 * <p>
    084 * In addition to this usage pattern there are some static convenience methods that
    085 * cover the most common use cases. These methods can be used without the need of
    086 * manually creating an instance. However if multiple replace operations are to be
    087 * performed, creating and reusing an instance of this class will be more efficient.
    088 * <p>
    089 * Variable replacement works in a recursive way. Thus, if a variable value contains
    090 * a variable then that variable will also be replaced. Cyclic replacements are
    091 * detected and will cause an exception to be thrown.
    092 * <p>
    093 * Sometimes the interpolation's result must contain a variable prefix. As an example
    094 * take the following source text:
    095 * <pre>
    096 *   The variable ${${name}} must be used.
    097 * </pre>
    098 * Here only the variable's name referred to in the text should be replaced resulting
    099 * in the text (assuming that the value of the {@code name} variable is {@code x}):
    100 * <pre>
    101 *   The variable ${x} must be used.
    102 * </pre>
    103 * To achieve this effect there are two possibilities: Either set a different prefix
    104 * and suffix for variables which do not conflict with the result text you want to
    105 * produce. The other possibility is to use the escape character, by default '$'.
    106 * If this character is placed before a variable reference, this reference is ignored
    107 * and won't be replaced. For example:
    108 * <pre>
    109 *   The variable $${${name}} must be used.
    110 * </pre>
    111 * <p>
    112 * In some complex scenarios you might even want to perform substitution in the
    113 * names of variables, for instance
    114 * <pre>
    115 * ${jre-${java.specification.version}}
    116 * </pre>
    117 * {@code StrSubstitutor} supports this recursive substitution in variable
    118 * names, but it has to be enabled explicitly by setting the
    119 * {@link #setEnableSubstitutionInVariables(boolean) enableSubstitutionInVariables}
    120 * property to <b>true</b>.
    121 * <p>This class is <b>not</b> thread safe.</p>
    122 *
    123 * @since 2.2
    124 * @deprecated as of 3.6, use commons-text
    125 * <a href="https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/StringSubstitutor.html">
    126 * StringSubstitutor</a> instead
    127 */
    128@Deprecated
    129public class StrSubstitutor {
    130
    131    /**
    132     * Constant for the default escape character.
    133     */
    134    public static final char DEFAULT_ESCAPE = '$';
    135    /**
    136     * Constant for the default variable prefix.
    137     */
    138    public static final StrMatcher DEFAULT_PREFIX = StrMatcher.stringMatcher("${");
    139    /**
    140     * Constant for the default variable suffix.
    141     */
    142    public static final StrMatcher DEFAULT_SUFFIX = StrMatcher.stringMatcher("}");
    143    /**
    144     * Constant for the default value delimiter of a variable.
    145     * @since 3.2
    146     */
    147    public static final StrMatcher DEFAULT_VALUE_DELIMITER = StrMatcher.stringMatcher(":-");
    148
    149    /**
    150     * Stores the escape character.
    151     */
    152    private char escapeChar;
    153    /**
    154     * Stores the variable prefix.
    155     */
    156    private StrMatcher prefixMatcher;
    157    /**
    158     * Stores the variable suffix.
    159     */
    160    private StrMatcher suffixMatcher;
    161    /**
    162     * Stores the default variable value delimiter
    163     */
    164    private StrMatcher valueDelimiterMatcher;
    165    /**
    166     * Variable resolution is delegated to an implementor of VariableResolver.
    167     */
    168    private StrLookup<?> variableResolver;
    169    /**
    170     * The flag whether substitution in variable names is enabled.
    171     */
    172    private boolean enableSubstitutionInVariables;
    173    /**
    174     * Whether escapes should be preserved.  Default is false;
    175     */
    176    private boolean preserveEscapes = false;
    177
    178    //-----------------------------------------------------------------------
    179    /**
    180     * Replaces all the occurrences of variables in the given source object with
    181     * their matching values from the map.
    182     *
    183     * @param <V> the type of the values in the map
    184     * @param source  the source text containing the variables to substitute, null returns null
    185     * @param valueMap  the map with the values, may be null
    186     * @return the result of the replace operation
    187     */
    188    public static <V> String replace(final Object source, final Map<String, V> valueMap) {
    189        return new StrSubstitutor(valueMap).replace(source);
    190    }
    191
    192    /**
    193     * Replaces all the occurrences of variables in the given source object with
    194     * their matching values from the map. This method allows to specify a
    195     * custom variable prefix and suffix
    196     *
    197     * @param <V> the type of the values in the map
    198     * @param source  the source text containing the variables to substitute, null returns null
    199     * @param valueMap  the map with the values, may be null
    200     * @param prefix  the prefix of variables, not null
    201     * @param suffix  the suffix of variables, not null
    202     * @return the result of the replace operation
    203     * @throws IllegalArgumentException if the prefix or suffix is null
    204     */
    205    public static <V> String replace(final Object source, final Map<String, V> valueMap, final String prefix, final String suffix) {
    206        return new StrSubstitutor(valueMap, prefix, suffix).replace(source);
    207    }
    208
    209    /**
    210     * Replaces all the occurrences of variables in the given source object with their matching
    211     * values from the properties.
    212     *
    213     * @param source the source text containing the variables to substitute, null returns null
    214     * @param valueProperties the properties with values, may be null
    215     * @return the result of the replace operation
    216     */
    217    public static String replace(final Object source, final Properties valueProperties) {
    218        if (valueProperties == null) {
    219            return source.toString();
    220        }
    221        final Map<String, String> valueMap = new HashMap<>();
    222        final Enumeration<?> propNames = valueProperties.propertyNames();
    223        while (propNames.hasMoreElements()) {
    224            final String propName = (String) propNames.nextElement();
    225            final String propValue = valueProperties.getProperty(propName);
    226            valueMap.put(propName, propValue);
    227        }
    228        return replace(source, valueMap);
    229    }
    230
    231    /**
    232     * Replaces all the occurrences of variables in the given source object with
    233     * their matching values from the system properties.
    234     *
    235     * @param source  the source text containing the variables to substitute, null returns null
    236     * @return the result of the replace operation
    237     */
    238    public static String replaceSystemProperties(final Object source) {
    239        return new StrSubstitutor(StrLookup.systemPropertiesLookup()).replace(source);
    240    }
    241
    242    //-----------------------------------------------------------------------
    243    /**
    244     * Creates a new instance with defaults for variable prefix and suffix
    245     * and the escaping character.
    246     */
    247    public StrSubstitutor() {
    248        this(null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
    249    }
    250
    251    /**
    252     * Creates a new instance and initializes it. Uses defaults for variable
    253     * prefix and suffix and the escaping character.
    254     *
    255     * @param <V> the type of the values in the map
    256     * @param valueMap  the map with the variables' values, may be null
    257     */
    258    public <V> StrSubstitutor(final Map<String, V> valueMap) {
    259        this(StrLookup.mapLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
    260    }
    261
    262    /**
    263     * Creates a new instance and initializes it. Uses a default escaping character.
    264     *
    265     * @param <V> the type of the values in the map
    266     * @param valueMap  the map with the variables' values, may be null
    267     * @param prefix  the prefix for variables, not null
    268     * @param suffix  the suffix for variables, not null
    269     * @throws IllegalArgumentException if the prefix or suffix is null
    270     */
    271    public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix) {
    272        this(StrLookup.mapLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE);
    273    }
    274
    275    /**
    276     * Creates a new instance and initializes it.
    277     *
    278     * @param <V> the type of the values in the map
    279     * @param valueMap  the map with the variables' values, may be null
    280     * @param prefix  the prefix for variables, not null
    281     * @param suffix  the suffix for variables, not null
    282     * @param escape  the escape character
    283     * @throws IllegalArgumentException if the prefix or suffix is null
    284     */
    285    public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
    286                              final char escape) {
    287        this(StrLookup.mapLookup(valueMap), prefix, suffix, escape);
    288    }
    289
    290    /**
    291     * Creates a new instance and initializes it.
    292     *
    293     * @param <V> the type of the values in the map
    294     * @param valueMap  the map with the variables' values, may be null
    295     * @param prefix  the prefix for variables, not null
    296     * @param suffix  the suffix for variables, not null
    297     * @param escape  the escape character
    298     * @param valueDelimiter  the variable default value delimiter, may be null
    299     * @throws IllegalArgumentException if the prefix or suffix is null
    300     * @since 3.2
    301     */
    302    public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
    303                              final char escape, final String valueDelimiter) {
    304        this(StrLookup.mapLookup(valueMap), prefix, suffix, escape, valueDelimiter);
    305    }
    306
    307    /**
    308     * Creates a new instance and initializes it.
    309     *
    310     * @param variableResolver  the variable resolver, may be null
    311     */
    312    public StrSubstitutor(final StrLookup<?> variableResolver) {
    313        this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
    314    }
    315
    316    /**
    317     * Creates a new instance and initializes it.
    318     *
    319     * @param variableResolver  the variable resolver, may be null
    320     * @param prefix  the prefix for variables, not null
    321     * @param suffix  the suffix for variables, not null
    322     * @param escape  the escape character
    323     * @throws IllegalArgumentException if the prefix or suffix is null
    324     */
    325    public StrSubstitutor(final StrLookup<?> variableResolver, final String prefix, final String suffix,
    326                          final char escape) {
    327        this.setVariableResolver(variableResolver);
    328        this.setVariablePrefix(prefix);
    329        this.setVariableSuffix(suffix);
    330        this.setEscapeChar(escape);
    331        this.setValueDelimiterMatcher(DEFAULT_VALUE_DELIMITER);
    332    }
    333
    334    /**
    335     * Creates a new instance and initializes it.
    336     *
    337     * @param variableResolver  the variable resolver, may be null
    338     * @param prefix  the prefix for variables, not null
    339     * @param suffix  the suffix for variables, not null
    340     * @param escape  the escape character
    341     * @param valueDelimiter  the variable default value delimiter string, may be null
    342     * @throws IllegalArgumentException if the prefix or suffix is null
    343     * @since 3.2
    344     */
    345    public StrSubstitutor(final StrLookup<?> variableResolver, final String prefix, final String suffix,
    346                          final char escape, final String valueDelimiter) {
    347        this.setVariableResolver(variableResolver);
    348        this.setVariablePrefix(prefix);
    349        this.setVariableSuffix(suffix);
    350        this.setEscapeChar(escape);
    351        this.setValueDelimiter(valueDelimiter);
    352    }
    353
    354    /**
    355     * Creates a new instance and initializes it.
    356     *
    357     * @param variableResolver  the variable resolver, may be null
    358     * @param prefixMatcher  the prefix for variables, not null
    359     * @param suffixMatcher  the suffix for variables, not null
    360     * @param escape  the escape character
    361     * @throws IllegalArgumentException if the prefix or suffix is null
    362     */
    363    public StrSubstitutor(
    364            final StrLookup<?> variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher,
    365            final char escape) {
    366        this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER);
    367    }
    368
    369    /**
    370     * Creates a new instance and initializes it.
    371     *
    372     * @param variableResolver  the variable resolver, may be null
    373     * @param prefixMatcher  the prefix for variables, not null
    374     * @param suffixMatcher  the suffix for variables, not null
    375     * @param escape  the escape character
    376     * @param valueDelimiterMatcher  the variable default value delimiter matcher, may be null
    377     * @throws IllegalArgumentException if the prefix or suffix is null
    378     * @since 3.2
    379     */
    380    public StrSubstitutor(
    381            final StrLookup<?> variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher,
    382            final char escape, final StrMatcher valueDelimiterMatcher) {
    383        this.setVariableResolver(variableResolver);
    384        this.setVariablePrefixMatcher(prefixMatcher);
    385        this.setVariableSuffixMatcher(suffixMatcher);
    386        this.setEscapeChar(escape);
    387        this.setValueDelimiterMatcher(valueDelimiterMatcher);
    388    }
    389
    390    //-----------------------------------------------------------------------
    391    /**
    392     * Replaces all the occurrences of variables with their matching values
    393     * from the resolver using the given source string as a template.
    394     *
    395     * @param source  the string to replace in, null returns null
    396     * @return the result of the replace operation
    397     */
    398    public String replace(final String source) {
    399        if (source == null) {
    400            return null;
    401        }
    402        final StrBuilder buf = new StrBuilder(source);
    403        if (substitute(buf, 0, source.length()) == false) {
    404            return source;
    405        }
    406        return buf.toString();
    407    }
    408
    409    /**
    410     * Replaces all the occurrences of variables with their matching values
    411     * from the resolver using the given source string as a template.
    412     * <p>
    413     * Only the specified portion of the string will be processed.
    414     * The rest of the string is not processed, and is not returned.
    415     *
    416     * @param source  the string to replace in, null returns null
    417     * @param offset  the start offset within the array, must be valid
    418     * @param length  the length within the array to be processed, must be valid
    419     * @return the result of the replace operation
    420     */
    421    public String replace(final String source, final int offset, final int length) {
    422        if (source == null) {
    423            return null;
    424        }
    425        final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
    426        if (substitute(buf, 0, length) == false) {
    427            return source.substring(offset, offset + length);
    428        }
    429        return buf.toString();
    430    }
    431
    432    //-----------------------------------------------------------------------
    433    /**
    434     * Replaces all the occurrences of variables with their matching values
    435     * from the resolver using the given source array as a template.
    436     * The array is not altered by this method.
    437     *
    438     * @param source  the character array to replace in, not altered, null returns null
    439     * @return the result of the replace operation
    440     */
    441    public String replace(final char[] source) {
    442        if (source == null) {
    443            return null;
    444        }
    445        final StrBuilder buf = new StrBuilder(source.length).append(source);
    446        substitute(buf, 0, source.length);
    447        return buf.toString();
    448    }
    449
    450    /**
    451     * Replaces all the occurrences of variables with their matching values
    452     * from the resolver using the given source array as a template.
    453     * The array is not altered by this method.
    454     * <p>
    455     * Only the specified portion of the array will be processed.
    456     * The rest of the array is not processed, and is not returned.
    457     *
    458     * @param source  the character array to replace in, not altered, null returns null
    459     * @param offset  the start offset within the array, must be valid
    460     * @param length  the length within the array to be processed, must be valid
    461     * @return the result of the replace operation
    462     */
    463    public String replace(final char[] source, final int offset, final int length) {
    464        if (source == null) {
    465            return null;
    466        }
    467        final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
    468        substitute(buf, 0, length);
    469        return buf.toString();
    470    }
    471
    472    //-----------------------------------------------------------------------
    473    /**
    474     * Replaces all the occurrences of variables with their matching values
    475     * from the resolver using the given source buffer as a template.
    476     * The buffer is not altered by this method.
    477     *
    478     * @param source  the buffer to use as a template, not changed, null returns null
    479     * @return the result of the replace operation
    480     */
    481    public String replace(final StringBuffer source) {
    482        if (source == null) {
    483            return null;
    484        }
    485        final StrBuilder buf = new StrBuilder(source.length()).append(source);
    486        substitute(buf, 0, buf.length());
    487        return buf.toString();
    488    }
    489
    490    /**
    491     * Replaces all the occurrences of variables with their matching values
    492     * from the resolver using the given source buffer as a template.
    493     * The buffer is not altered by this method.
    494     * <p>
    495     * Only the specified portion of the buffer will be processed.
    496     * The rest of the buffer is not processed, and is not returned.
    497     *
    498     * @param source  the buffer to use as a template, not changed, null returns null
    499     * @param offset  the start offset within the array, must be valid
    500     * @param length  the length within the array to be processed, must be valid
    501     * @return the result of the replace operation
    502     */
    503    public String replace(final StringBuffer source, final int offset, final int length) {
    504        if (source == null) {
    505            return null;
    506        }
    507        final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
    508        substitute(buf, 0, length);
    509        return buf.toString();
    510    }
    511
    512    /**
    513     * Replaces all the occurrences of variables with their matching values
    514     * from the resolver using the given source as a template.
    515     * The source is not altered by this method.
    516     *
    517     * @param source  the buffer to use as a template, not changed, null returns null
    518     * @return the result of the replace operation
    519     * @since 3.2
    520     */
    521    public String replace(final CharSequence source) {
    522        if (source == null) {
    523            return null;
    524        }
    525        return replace(source, 0, source.length());
    526    }
    527
    528    /**
    529     * Replaces all the occurrences of variables with their matching values
    530     * from the resolver using the given source as a template.
    531     * The source is not altered by this method.
    532     * <p>
    533     * Only the specified portion of the buffer will be processed.
    534     * The rest of the buffer is not processed, and is not returned.
    535     *
    536     * @param source  the buffer to use as a template, not changed, null returns null
    537     * @param offset  the start offset within the array, must be valid
    538     * @param length  the length within the array to be processed, must be valid
    539     * @return the result of the replace operation
    540     * @since 3.2
    541     */
    542    public String replace(final CharSequence source, final int offset, final int length) {
    543        if (source == null) {
    544            return null;
    545        }
    546        final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
    547        substitute(buf, 0, length);
    548        return buf.toString();
    549    }
    550
    551    //-----------------------------------------------------------------------
    552    /**
    553     * Replaces all the occurrences of variables with their matching values
    554     * from the resolver using the given source builder as a template.
    555     * The builder is not altered by this method.
    556     *
    557     * @param source  the builder to use as a template, not changed, null returns null
    558     * @return the result of the replace operation
    559     */
    560    public String replace(final StrBuilder source) {
    561        if (source == null) {
    562            return null;
    563        }
    564        final StrBuilder buf = new StrBuilder(source.length()).append(source);
    565        substitute(buf, 0, buf.length());
    566        return buf.toString();
    567    }
    568
    569    /**
    570     * Replaces all the occurrences of variables with their matching values
    571     * from the resolver using the given source builder as a template.
    572     * The builder is not altered by this method.
    573     * <p>
    574     * Only the specified portion of the builder will be processed.
    575     * The rest of the builder is not processed, and is not returned.
    576     *
    577     * @param source  the builder to use as a template, not changed, null returns null
    578     * @param offset  the start offset within the array, must be valid
    579     * @param length  the length within the array to be processed, must be valid
    580     * @return the result of the replace operation
    581     */
    582    public String replace(final StrBuilder source, final int offset, final int length) {
    583        if (source == null) {
    584            return null;
    585        }
    586        final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
    587        substitute(buf, 0, length);
    588        return buf.toString();
    589    }
    590
    591    //-----------------------------------------------------------------------
    592    /**
    593     * Replaces all the occurrences of variables in the given source object with
    594     * their matching values from the resolver. The input source object is
    595     * converted to a string using {@code toString} and is not altered.
    596     *
    597     * @param source  the source to replace in, null returns null
    598     * @return the result of the replace operation
    599     */
    600    public String replace(final Object source) {
    601        if (source == null) {
    602            return null;
    603        }
    604        final StrBuilder buf = new StrBuilder().append(source);
    605        substitute(buf, 0, buf.length());
    606        return buf.toString();
    607    }
    608
    609    //-----------------------------------------------------------------------
    610    /**
    611     * Replaces all the occurrences of variables within the given source buffer
    612     * with their matching values from the resolver.
    613     * The buffer is updated with the result.
    614     *
    615     * @param source  the buffer to replace in, updated, null returns zero
    616     * @return true if altered
    617     */
    618    public boolean replaceIn(final StringBuffer source) {
    619        if (source == null) {
    620            return false;
    621        }
    622        return replaceIn(source, 0, source.length());
    623    }
    624
    625    /**
    626     * Replaces all the occurrences of variables within the given source buffer
    627     * with their matching values from the resolver.
    628     * The buffer is updated with the result.
    629     * <p>
    630     * Only the specified portion of the buffer will be processed.
    631     * The rest of the buffer is not processed, but it is not deleted.
    632     *
    633     * @param source  the buffer to replace in, updated, null returns zero
    634     * @param offset  the start offset within the array, must be valid
    635     * @param length  the length within the buffer to be processed, must be valid
    636     * @return true if altered
    637     */
    638    public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
    639        if (source == null) {
    640            return false;
    641        }
    642        final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
    643        if (substitute(buf, 0, length) == false) {
    644            return false;
    645        }
    646        source.replace(offset, offset + length, buf.toString());
    647        return true;
    648    }
    649
    650  //-----------------------------------------------------------------------
    651    /**
    652     * Replaces all the occurrences of variables within the given source buffer
    653     * with their matching values from the resolver.
    654     * The buffer is updated with the result.
    655     *
    656     * @param source  the buffer to replace in, updated, null returns zero
    657     * @return true if altered
    658     * @since 3.2
    659     */
    660    public boolean replaceIn(final StringBuilder source) {
    661        if (source == null) {
    662            return false;
    663        }
    664        return replaceIn(source, 0, source.length());
    665    }
    666
    667    /**
    668     * Replaces all the occurrences of variables within the given source builder
    669     * with their matching values from the resolver.
    670     * The builder is updated with the result.
    671     * <p>
    672     * Only the specified portion of the buffer will be processed.
    673     * The rest of the buffer is not processed, but it is not deleted.
    674     *
    675     * @param source  the buffer to replace in, updated, null returns zero
    676     * @param offset  the start offset within the array, must be valid
    677     * @param length  the length within the buffer to be processed, must be valid
    678     * @return true if altered
    679     * @since 3.2
    680     */
    681    public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
    682        if (source == null) {
    683            return false;
    684        }
    685        final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
    686        if (substitute(buf, 0, length) == false) {
    687            return false;
    688        }
    689        source.replace(offset, offset + length, buf.toString());
    690        return true;
    691    }
    692
    693    //-----------------------------------------------------------------------
    694    /**
    695     * Replaces all the occurrences of variables within the given source
    696     * builder with their matching values from the resolver.
    697     *
    698     * @param source  the builder to replace in, updated, null returns zero
    699     * @return true if altered
    700     */
    701    public boolean replaceIn(final StrBuilder source) {
    702        if (source == null) {
    703            return false;
    704        }
    705        return substitute(source, 0, source.length());
    706    }
    707
    708    /**
    709     * Replaces all the occurrences of variables within the given source
    710     * builder with their matching values from the resolver.
    711     * <p>
    712     * Only the specified portion of the builder will be processed.
    713     * The rest of the builder is not processed, but it is not deleted.
    714     *
    715     * @param source  the builder to replace in, null returns zero
    716     * @param offset  the start offset within the array, must be valid
    717     * @param length  the length within the builder to be processed, must be valid
    718     * @return true if altered
    719     */
    720    public boolean replaceIn(final StrBuilder source, final int offset, final int length) {
    721        if (source == null) {
    722            return false;
    723        }
    724        return substitute(source, offset, length);
    725    }
    726
    727    //-----------------------------------------------------------------------
    728    /**
    729     * Internal method that substitutes the variables.
    730     * <p>
    731     * Most users of this class do not need to call this method. This method will
    732     * be called automatically by another (public) method.
    733     * <p>
    734     * Writers of subclasses can override this method if they need access to
    735     * the substitution process at the start or end.
    736     *
    737     * @param buf  the string builder to substitute into, not null
    738     * @param offset  the start offset within the builder, must be valid
    739     * @param length  the length within the builder to be processed, must be valid
    740     * @return true if altered
    741     */
    742    protected boolean substitute(final StrBuilder buf, final int offset, final int length) {
    743        return substitute(buf, offset, length, null) > 0;
    744    }
    745
    746    /**
    747     * Recursive handler for multiple levels of interpolation. This is the main
    748     * interpolation method, which resolves the values of all variable references
    749     * contained in the passed in text.
    750     *
    751     * @param buf  the string builder to substitute into, not null
    752     * @param offset  the start offset within the builder, must be valid
    753     * @param length  the length within the builder to be processed, must be valid
    754     * @param priorVariables  the stack keeping track of the replaced variables, may be null
    755     * @return the length change that occurs, unless priorVariables is null when the int
    756     *  represents a boolean flag as to whether any change occurred.
    757     */
    758    private int substitute(final StrBuilder buf, final int offset, final int length, List<String> priorVariables) {
    759        final StrMatcher pfxMatcher = getVariablePrefixMatcher();
    760        final StrMatcher suffMatcher = getVariableSuffixMatcher();
    761        final char escape = getEscapeChar();
    762        final StrMatcher valueDelimMatcher = getValueDelimiterMatcher();
    763        final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
    764
    765        final boolean top = priorVariables == null;
    766        boolean altered = false;
    767        int lengthChange = 0;
    768        char[] chars = buf.buffer;
    769        int bufEnd = offset + length;
    770        int pos = offset;
    771        while (pos < bufEnd) {
    772            final int startMatchLen = pfxMatcher.isMatch(chars, pos, offset,
    773                    bufEnd);
    774            if (startMatchLen == 0) {
    775                pos++;
    776            } else {
    777                // found variable start marker
    778                if (pos > offset && chars[pos - 1] == escape) {
    779                    // escaped
    780                    if (preserveEscapes) {
    781                        pos++;
    782                        continue;
    783                    }
    784                    buf.deleteCharAt(pos - 1);
    785                    chars = buf.buffer; // in case buffer was altered
    786                    lengthChange--;
    787                    altered = true;
    788                    bufEnd--;
    789                } else {
    790                    // find suffix
    791                    final int startPos = pos;
    792                    pos += startMatchLen;
    793                    int endMatchLen = 0;
    794                    int nestedVarCount = 0;
    795                    while (pos < bufEnd) {
    796                        if (substitutionInVariablesEnabled
    797                                && (endMatchLen = pfxMatcher.isMatch(chars,
    798                                        pos, offset, bufEnd)) != 0) {
    799                            // found a nested variable start
    800                            nestedVarCount++;
    801                            pos += endMatchLen;
    802                            continue;
    803                        }
    804
    805                        endMatchLen = suffMatcher.isMatch(chars, pos, offset,
    806                                bufEnd);
    807                        if (endMatchLen == 0) {
    808                            pos++;
    809                        } else {
    810                            // found variable end marker
    811                            if (nestedVarCount == 0) {
    812                                String varNameExpr = new String(chars, startPos
    813                                        + startMatchLen, pos - startPos
    814                                        - startMatchLen);
    815                                if (substitutionInVariablesEnabled) {
    816                                    final StrBuilder bufName = new StrBuilder(varNameExpr);
    817                                    substitute(bufName, 0, bufName.length());
    818                                    varNameExpr = bufName.toString();
    819                                }
    820                                pos += endMatchLen;
    821                                final int endPos = pos;
    822
    823                                String varName = varNameExpr;
    824                                String varDefaultValue = null;
    825
    826                                if (valueDelimMatcher != null) {
    827                                    final char [] varNameExprChars = varNameExpr.toCharArray();
    828                                    int valueDelimiterMatchLen = 0;
    829                                    for (int i = 0; i < varNameExprChars.length; i++) {
    830                                        // if there's any nested variable when nested variable substitution disabled, then stop resolving name and default value.
    831                                        if (!substitutionInVariablesEnabled
    832                                                && pfxMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) {
    833                                            break;
    834                                        }
    835                                        if ((valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i)) != 0) {
    836                                            varName = varNameExpr.substring(0, i);
    837                                            varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
    838                                            break;
    839                                        }
    840                                    }
    841                                }
    842
    843                                // on the first call initialize priorVariables
    844                                if (priorVariables == null) {
    845                                    priorVariables = new ArrayList<>();
    846                                    priorVariables.add(new String(chars,
    847                                            offset, length));
    848                                }
    849
    850                                // handle cyclic substitution
    851                                checkCyclicSubstitution(varName, priorVariables);
    852                                priorVariables.add(varName);
    853
    854                                // resolve the variable
    855                                String varValue = resolveVariable(varName, buf,
    856                                        startPos, endPos);
    857                                if (varValue == null) {
    858                                    varValue = varDefaultValue;
    859                                }
    860                                if (varValue != null) {
    861                                    // recursive replace
    862                                    final int varLen = varValue.length();
    863                                    buf.replace(startPos, endPos, varValue);
    864                                    altered = true;
    865                                    int change = substitute(buf, startPos,
    866                                            varLen, priorVariables);
    867                                    change = change
    868                                            + varLen - (endPos - startPos);
    869                                    pos += change;
    870                                    bufEnd += change;
    871                                    lengthChange += change;
    872                                    chars = buf.buffer; // in case buffer was
    873                                                        // altered
    874                                }
    875
    876                                // remove variable from the cyclic stack
    877                                priorVariables
    878                                        .remove(priorVariables.size() - 1);
    879                                break;
    880                            }
    881                            nestedVarCount--;
    882                            pos += endMatchLen;
    883                        }
    884                    }
    885                }
    886            }
    887        }
    888        if (top) {
    889            return altered ? 1 : 0;
    890        }
    891        return lengthChange;
    892    }
    893
    894    /**
    895     * Checks if the specified variable is already in the stack (list) of variables.
    896     *
    897     * @param varName  the variable name to check
    898     * @param priorVariables  the list of prior variables
    899     */
    900    private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) {
    901        if (priorVariables.contains(varName) == false) {
    902            return;
    903        }
    904        final StrBuilder buf = new StrBuilder(256);
    905        buf.append("Infinite loop in property interpolation of ");
    906        buf.append(priorVariables.remove(0));
    907        buf.append(": ");
    908        buf.appendWithSeparators(priorVariables, "->");
    909        throw new IllegalStateException(buf.toString());
    910    }
    911
    912    /**
    913     * Internal method that resolves the value of a variable.
    914     * <p>
    915     * Most users of this class do not need to call this method. This method is
    916     * called automatically by the substitution process.
    917     * <p>
    918     * Writers of subclasses can override this method if they need to alter
    919     * how each substitution occurs. The method is passed the variable's name
    920     * and must return the corresponding value. This implementation uses the
    921     * {@link #getVariableResolver()} with the variable's name as the key.
    922     *
    923     * @param variableName  the name of the variable, not null
    924     * @param buf  the buffer where the substitution is occurring, not null
    925     * @param startPos  the start position of the variable including the prefix, valid
    926     * @param endPos  the end position of the variable including the suffix, valid
    927     * @return the variable's value or <b>null</b> if the variable is unknown
    928     */
    929    protected String resolveVariable(final String variableName, final StrBuilder buf, final int startPos, final int endPos) {
    930        final StrLookup<?> resolver = getVariableResolver();
    931        if (resolver == null) {
    932            return null;
    933        }
    934        return resolver.lookup(variableName);
    935    }
    936
    937    // Escape
    938    //-----------------------------------------------------------------------
    939    /**
    940     * Returns the escape character.
    941     *
    942     * @return the character used for escaping variable references
    943     */
    944    public char getEscapeChar() {
    945        return this.escapeChar;
    946    }
    947
    948    /**
    949     * Sets the escape character.
    950     * If this character is placed before a variable reference in the source
    951     * text, this variable will be ignored.
    952     *
    953     * @param escapeCharacter  the escape character (0 for disabling escaping)
    954     */
    955    public void setEscapeChar(final char escapeCharacter) {
    956        this.escapeChar = escapeCharacter;
    957    }
    958
    959    // Prefix
    960    //-----------------------------------------------------------------------
    961    /**
    962     * Gets the variable prefix matcher currently in use.
    963     * <p>
    964     * The variable prefix is the character or characters that identify the
    965     * start of a variable. This prefix is expressed in terms of a matcher
    966     * allowing advanced prefix matches.
    967     *
    968     * @return the prefix matcher in use
    969     */
    970    public StrMatcher getVariablePrefixMatcher() {
    971        return prefixMatcher;
    972    }
    973
    974    /**
    975     * Sets the variable prefix matcher currently in use.
    976     * <p>
    977     * The variable prefix is the character or characters that identify the
    978     * start of a variable. This prefix is expressed in terms of a matcher
    979     * allowing advanced prefix matches.
    980     *
    981     * @param prefixMatcher  the prefix matcher to use, null ignored
    982     * @return this, to enable chaining
    983     * @throws IllegalArgumentException if the prefix matcher is null
    984     */
    985    public StrSubstitutor setVariablePrefixMatcher(final StrMatcher prefixMatcher) {
    986        if (prefixMatcher == null) {
    987            throw new IllegalArgumentException("Variable prefix matcher must not be null.");
    988        }
    989        this.prefixMatcher = prefixMatcher;
    990        return this;
    991    }
    992
    993    /**
    994     * Sets the variable prefix to use.
    995     * <p>
    996     * The variable prefix is the character or characters that identify the
    997     * start of a variable. This method allows a single character prefix to
    998     * be easily set.
    999     *
    1000     * @param prefix  the prefix character to use
    1001     * @return this, to enable chaining
    1002     */
    1003    public StrSubstitutor setVariablePrefix(final char prefix) {
    1004        return setVariablePrefixMatcher(StrMatcher.charMatcher(prefix));
    1005    }
    1006
    1007    /**
    1008     * Sets the variable prefix to use.
    1009     * <p>
    1010     * The variable prefix is the character or characters that identify the
    1011     * start of a variable. This method allows a string prefix to be easily set.
    1012     *
    1013     * @param prefix  the prefix for variables, not null
    1014     * @return this, to enable chaining
    1015     * @throws IllegalArgumentException if the prefix is null
    1016     */
    1017    public StrSubstitutor setVariablePrefix(final String prefix) {
    1018       if (prefix == null) {
    1019            throw new IllegalArgumentException("Variable prefix must not be null.");
    1020        }
    1021        return setVariablePrefixMatcher(StrMatcher.stringMatcher(prefix));
    1022    }
    1023
    1024    // Suffix
    1025    //-----------------------------------------------------------------------
    1026    /**
    1027     * Gets the variable suffix matcher currently in use.
    1028     * <p>
    1029     * The variable suffix is the character or characters that identify the
    1030     * end of a variable. This suffix is expressed in terms of a matcher
    1031     * allowing advanced suffix matches.
    1032     *
    1033     * @return the suffix matcher in use
    1034     */
    1035    public StrMatcher getVariableSuffixMatcher() {
    1036        return suffixMatcher;
    1037    }
    1038
    1039    /**
    1040     * Sets the variable suffix matcher currently in use.
    1041     * <p>
    1042     * The variable suffix is the character or characters that identify the
    1043     * end of a variable. This suffix is expressed in terms of a matcher
    1044     * allowing advanced suffix matches.
    1045     *
    1046     * @param suffixMatcher  the suffix matcher to use, null ignored
    1047     * @return this, to enable chaining
    1048     * @throws IllegalArgumentException if the suffix matcher is null
    1049     */
    1050    public StrSubstitutor setVariableSuffixMatcher(final StrMatcher suffixMatcher) {
    1051        if (suffixMatcher == null) {
    1052            throw new IllegalArgumentException("Variable suffix matcher must not be null.");
    1053        }
    1054        this.suffixMatcher = suffixMatcher;
    1055        return this;
    1056    }
    1057
    1058    /**
    1059     * Sets the variable suffix to use.
    1060     * <p>
    1061     * The variable suffix is the character or characters that identify the
    1062     * end of a variable. This method allows a single character suffix to
    1063     * be easily set.
    1064     *
    1065     * @param suffix  the suffix character to use
    1066     * @return this, to enable chaining
    1067     */
    1068    public StrSubstitutor setVariableSuffix(final char suffix) {
    1069        return setVariableSuffixMatcher(StrMatcher.charMatcher(suffix));
    1070    }
    1071
    1072    /**
    1073     * Sets the variable suffix to use.
    1074     * <p>
    1075     * The variable suffix is the character or characters that identify the
    1076     * end of a variable. This method allows a string suffix to be easily set.
    1077     *
    1078     * @param suffix  the suffix for variables, not null
    1079     * @return this, to enable chaining
    1080     * @throws IllegalArgumentException if the suffix is null
    1081     */
    1082    public StrSubstitutor setVariableSuffix(final String suffix) {
    1083       if (suffix == null) {
    1084            throw new IllegalArgumentException("Variable suffix must not be null.");
    1085        }
    1086        return setVariableSuffixMatcher(StrMatcher.stringMatcher(suffix));
    1087    }
    1088
    1089    // Variable Default Value Delimiter
    1090    //-----------------------------------------------------------------------
    1091    /**
    1092     * Gets the variable default value delimiter matcher currently in use.
    1093     * <p>
    1094     * The variable default value delimiter is the character or characters that delimit the
    1095     * variable name and the variable default value. This delimiter is expressed in terms of a matcher
    1096     * allowing advanced variable default value delimiter matches.
    1097     * <p>
    1098     * If it returns null, then the variable default value resolution is disabled.
    1099     *
    1100     * @return the variable default value delimiter matcher in use, may be null
    1101     * @since 3.2
    1102     */
    1103    public StrMatcher getValueDelimiterMatcher() {
    1104        return valueDelimiterMatcher;
    1105    }
    1106
    1107    /**
    1108     * Sets the variable default value delimiter matcher to use.
    1109     * <p>
    1110     * The variable default value delimiter is the character or characters that delimit the
    1111     * variable name and the variable default value. This delimiter is expressed in terms of a matcher
    1112     * allowing advanced variable default value delimiter matches.
    1113     * <p>
    1114     * If the {@code valueDelimiterMatcher} is null, then the variable default value resolution
    1115     * becomes disabled.
    1116     *
    1117     * @param valueDelimiterMatcher  variable default value delimiter matcher to use, may be null
    1118     * @return this, to enable chaining
    1119     * @since 3.2
    1120     */
    1121    public StrSubstitutor setValueDelimiterMatcher(final StrMatcher valueDelimiterMatcher) {
    1122        this.valueDelimiterMatcher = valueDelimiterMatcher;
    1123        return this;
    1124    }
    1125
    1126    /**
    1127     * Sets the variable default value delimiter to use.
    1128     * <p>
    1129     * The variable default value delimiter is the character or characters that delimit the
    1130     * variable name and the variable default value. This method allows a single character
    1131     * variable default value delimiter to be easily set.
    1132     *
    1133     * @param valueDelimiter  the variable default value delimiter character to use
    1134     * @return this, to enable chaining
    1135     * @since 3.2
    1136     */
    1137    public StrSubstitutor setValueDelimiter(final char valueDelimiter) {
    1138        return setValueDelimiterMatcher(StrMatcher.charMatcher(valueDelimiter));
    1139    }
    1140
    1141    /**
    1142     * Sets the variable default value delimiter to use.
    1143     * <p>
    1144     * The variable default value delimiter is the character or characters that delimit the
    1145     * variable name and the variable default value. This method allows a string
    1146     * variable default value delimiter to be easily set.
    1147     * <p>
    1148     * If the {@code valueDelimiter} is null or empty string, then the variable default
    1149     * value resolution becomes disabled.
    1150     *
    1151     * @param valueDelimiter  the variable default value delimiter string to use, may be null or empty
    1152     * @return this, to enable chaining
    1153     * @since 3.2
    1154     */
    1155    public StrSubstitutor setValueDelimiter(final String valueDelimiter) {
    1156        if (StringUtils.isEmpty(valueDelimiter)) {
    1157            setValueDelimiterMatcher(null);
    1158            return this;
    1159        }
    1160        return setValueDelimiterMatcher(StrMatcher.stringMatcher(valueDelimiter));
    1161    }
    1162
    1163    // Resolver
    1164    //-----------------------------------------------------------------------
    1165    /**
    1166     * Gets the VariableResolver that is used to lookup variables.
    1167     *
    1168     * @return the VariableResolver
    1169     */
    1170    public StrLookup<?> getVariableResolver() {
    1171        return this.variableResolver;
    1172    }
    1173
    1174    /**
    1175     * Sets the VariableResolver that is used to lookup variables.
    1176     *
    1177     * @param variableResolver  the VariableResolver
    1178     */
    1179    public void setVariableResolver(final StrLookup<?> variableResolver) {
    1180        this.variableResolver = variableResolver;
    1181    }
    1182
    1183    // Substitution support in variable names
    1184    //-----------------------------------------------------------------------
    1185    /**
    1186     * Returns a flag whether substitution is done in variable names.
    1187     *
    1188     * @return the substitution in variable names flag
    1189     * @since 3.0
    1190     */
    1191    public boolean isEnableSubstitutionInVariables() {
    1192        return enableSubstitutionInVariables;
    1193    }
    1194
    1195    /**
    1196     * Sets a flag whether substitution is done in variable names. If set to
    1197     * <b>true</b>, the names of variables can contain other variables which are
    1198     * processed first before the original variable is evaluated, e.g.
    1199     * {@code ${jre-${java.version}}}. The default value is <b>false</b>.
    1200     *
    1201     * @param enableSubstitutionInVariables the new value of the flag
    1202     * @since 3.0
    1203     */
    1204    public void setEnableSubstitutionInVariables(
    1205            final boolean enableSubstitutionInVariables) {
    1206        this.enableSubstitutionInVariables = enableSubstitutionInVariables;
    1207    }
    1208
    1209    /**
    1210     * Returns the flag controlling whether escapes are preserved during
    1211     * substitution.
    1212     *
    1213     * @return the preserve escape flag
    1214     * @since 3.5
    1215     */
    1216    public boolean isPreserveEscapes() {
    1217        return preserveEscapes;
    1218    }
    1219
    1220    /**
    1221     * Sets a flag controlling whether escapes are preserved during
    1222     * substitution.  If set to <b>true</b>, the escape character is retained
    1223     * during substitution (e.g. {@code $${this-is-escaped}} remains
    1224     * {@code $${this-is-escaped}}).  If set to <b>false</b>, the escape
    1225     * character is removed during substitution (e.g.
    1226     * {@code $${this-is-escaped}} becomes
    1227     * {@code ${this-is-escaped}}).  The default value is <b>false</b>
    1228     *
    1229     * @param preserveEscapes true if escapes are to be preserved
    1230     * @since 3.5
    1231     */
    1232    public void setPreserveEscapes(final boolean preserveEscapes) {
    1233        this.preserveEscapes = preserveEscapes;
    1234    }
    1235}