/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.lang.text;

import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;

Substitutes variables within a string by values.

This class takes a piece of text and substitutes all the variables within it.
The default definition of a variable is ${variableName}.
The prefix and suffix can be changed via constructors and set methods.

Variable values are typically resolved from a map, but could also be resolved
from system properties, or by supplying a custom variable resolver.

The simplest example is to use this class to replace Java System properties. For example:
StrSubstitutor.replaceSystemProperties(
     "You are running with java.version = ${java.version} and os.name = ${os.name}.");


Typical usage of this class follows the following pattern: First an instance is created
and initialized with the map that contains the values for the available variables.
If a prefix and/or suffix for variables should be used other than the default ones,
the appropriate settings can be performed. After that the replace()
method can be called passing in the source text for interpolation. In the returned
text all variable references (as long as their values are known) will be resolved.
The following example demonstrates this:
Map valuesMap = HashMap();
valuesMap.put("animal", "quick brown fox");
valuesMap.put("target", "lazy dog");
String templateString = "The ${animal} jumped over the ${target}.";
StrSubstitutor sub = new StrSubstitutor(valuesMap);
String resolvedString = sub.replace(templateString);

yielding:
     The quick brown fox jumped over the lazy dog.


In addition to this usage pattern there are some static convenience methods that
cover the most common use cases. These methods can be used without the need of
manually creating an instance. However if multiple replace operations are to be
performed, creating and reusing an instance of this class will be more efficient.

Variable replacement works in a recursive way. Thus, if a variable value contains
a variable then that variable will also be replaced. Cyclic replacements are
detected and will cause an exception to be thrown.

Sometimes the interpolation's result must contain a variable prefix. As an example
take the following source text:
  The variable ${${name}} must be used.

Here only the variable's name referred to in the text should be replaced resulting
in the text (assuming that the value of the name variable is x):
  The variable ${x} must be used.

To achieve this effect there are two possibilities: Either set a different prefix
and suffix for variables which do not conflict with the result text you want to
produce. The other possibility is to use the escape character, by default '$'.
If this character is placed before a variable reference, this reference is ignored
and won't be replaced. For example:
  The variable $${${name}} must be used.


In some complex scenarios you might even want to perform substitution in the
names of variables, for instance
${jre-${java.specification.version}}

StrSubstitutor supports this recursive substitution in variable names, but it has to be enabled explicitly by setting the enableSubstitutionInVariables property to true.
Author:
Apache Software Foundation, Oliver Heger
Version:
$Id: StrSubstitutor.java 1057354 2011-01-10 20:48:47Z niallp $
Since:
2.2/**
 * Substitutes variables within a string by values.
 * <p>
 * This class takes a piece of text and substitutes all the variables within it.
 * The default definition of a variable is <code>${variableName}</code>.
 * The prefix and suffix can be changed via constructors and set methods.
 * <p>
 * Variable values are typically resolved from a map, but could also be resolved
 * from system properties, or by supplying a custom variable resolver.
 * <p>
 * The simplest example is to use this class to replace Java System properties. For example:
 * <pre>
 * StrSubstitutor.replaceSystemProperties(
 *      "You are running with java.version = ${java.version} and os.name = ${os.name}.");
 * </pre>
 * <p>
 * Typical usage of this class follows the following pattern: First an instance is created
 * and initialized with the map that contains the values for the available variables.
 * If a prefix and/or suffix for variables should be used other than the default ones,
 * the appropriate settings can be performed. After that the <code>replace()</code>
 * method can be called passing in the source text for interpolation. In the returned
 * text all variable references (as long as their values are known) will be resolved.
 * The following example demonstrates this:
 * <pre>
 * Map valuesMap = HashMap();
 * valuesMap.put(&quot;animal&quot;, &quot;quick brown fox&quot;);
 * valuesMap.put(&quot;target&quot;, &quot;lazy dog&quot;);
 * String templateString = &quot;The ${animal} jumped over the ${target}.&quot;;
 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
 * String resolvedString = sub.replace(templateString);
 * </pre>
 * yielding:
 * <pre>
 *      The quick brown fox jumped over the lazy dog.
 * </pre>
 * <p>
 * In addition to this usage pattern there are some static convenience methods that
 * cover the most common use cases. These methods can be used without the need of
 * manually creating an instance. However if multiple replace operations are to be
 * performed, creating and reusing an instance of this class will be more efficient.
 * <p>
 * Variable replacement works in a recursive way. Thus, if a variable value contains
 * a variable then that variable will also be replaced. Cyclic replacements are
 * detected and will cause an exception to be thrown.
 * <p>
 * Sometimes the interpolation's result must contain a variable prefix. As an example
 * take the following source text:
 * <pre>
 *   The variable ${${name}} must be used.
 * </pre>
 * Here only the variable's name referred to in the text should be replaced resulting
 * in the text (assuming that the value of the <code>name</code> variable is <code>x</code>):
 * <pre>
 *   The variable ${x} must be used.
 * </pre>
 * To achieve this effect there are two possibilities: Either set a different prefix
 * and suffix for variables which do not conflict with the result text you want to
 * produce. The other possibility is to use the escape character, by default '$'.
 * If this character is placed before a variable reference, this reference is ignored
 * and won't be replaced. For example:
 * <pre>
 *   The variable $${${name}} must be used.
 * </pre>
 * <p>
 * In some complex scenarios you might even want to perform substitution in the
 * names of variables, for instance
 * <pre>
 * ${jre-${java.specification.version}}
 * </pre>
 * <code>StrSubstitutor</code> supports this recursive substitution in variable
 * names, but it has to be enabled explicitly by setting the
 * {@link #setEnableSubstitutionInVariables(boolean) enableSubstitutionInVariables}
 * property to <b>true</b>.
 *
 * @author Apache Software Foundation
 * @author Oliver Heger
 * @version $Id: StrSubstitutor.java 1057354 2011-01-10 20:48:47Z niallp $
 * @since 2.2
 */
public class StrSubstitutor {

    
Constant for the default escape character.
/**
     * Constant for the default escape character.
     */
    public static final char DEFAULT_ESCAPE = '$';
    
Constant for the default variable prefix.
/**
     * Constant for the default variable prefix.
     */
    public static final StrMatcher DEFAULT_PREFIX = StrMatcher.stringMatcher("${");
    
Constant for the default variable suffix.
/**
     * Constant for the default variable suffix.
     */
    public static final StrMatcher DEFAULT_SUFFIX = StrMatcher.stringMatcher("}");

    
Stores the escape character.
/**
     * Stores the escape character.
     */
    private char escapeChar;
    
Stores the variable prefix.
/**
     * Stores the variable prefix.
     */
    private StrMatcher prefixMatcher;
    
Stores the variable suffix.
/**
     * Stores the variable suffix.
     */
    private StrMatcher suffixMatcher;
    
Variable resolution is delegated to an implementor of VariableResolver.
/**
     * Variable resolution is delegated to an implementor of VariableResolver.
     */
    private StrLookup variableResolver;
    
The flag whether substitution in variable names is enabled.
/**
     * The flag whether substitution in variable names is enabled.
     */
    private boolean enableSubstitutionInVariables;

    //-----------------------------------------------------------------------
    
Replaces all the occurrences of variables in the given source object with
their matching values from the map.
Params:
source –  the source text containing the variables to substitute, null returns null
valueMap –  the map with the values, may be null
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables in the given source object with
     * their matching values from the map.
     *
     * @param source  the source text containing the variables to substitute, null returns null
     * @param valueMap  the map with the values, may be null
     * @return the result of the replace operation
     */
    public static String replace(Object source, Map valueMap) {
        return new StrSubstitutor(valueMap).replace(source);
    }

    
Replaces all the occurrences of variables in the given source object with
their matching values from the map. This method allows to specifiy a
custom variable prefix and suffix
Params:
source –  the source text containing the variables to substitute, null returns null
valueMap –  the map with the values, may be null
prefix –  the prefix of variables, not null
suffix –  the suffix of variables, not null
Throws:
IllegalArgumentException – if the prefix or suffix is null
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables in the given source object with
     * their matching values from the map. This method allows to specifiy a
     * custom variable prefix and suffix
     *
     * @param source  the source text containing the variables to substitute, null returns null
     * @param valueMap  the map with the values, may be null
     * @param prefix  the prefix of variables, not null
     * @param suffix  the suffix of variables, not null
     * @return the result of the replace operation
     * @throws IllegalArgumentException if the prefix or suffix is null
     */
    public static String replace(Object source, Map valueMap, String prefix, String suffix) {
        return new StrSubstitutor(valueMap, prefix, suffix).replace(source);
    }

    
Replaces all the occurrences of variables in the given source object with their matching
values from the properties.
Params:
source – the source text containing the variables to substitute, null returns null
valueProperties – the properties with values, may be null
Returns:
the result of the replace operation
Since:
2.6/**
     * Replaces all the occurrences of variables in the given source object with their matching
     * values from the properties.
     *
     * @param source the source text containing the variables to substitute, null returns null
     * @param valueProperties the properties with values, may be null
     * @return the result of the replace operation
     * @since 2.6
     */
    public static String replace(Object source, Properties valueProperties)
    {
        if (valueProperties == null) {
            return source.toString();
        }
        Map valueMap = new HashMap();
        Enumeration propNames = valueProperties.propertyNames();
        while (propNames.hasMoreElements())
        {
            String propName = (String)propNames.nextElement();
            String propValue = valueProperties.getProperty(propName);
            valueMap.put(propName, propValue);
        }
        return StrSubstitutor.replace(source, valueMap);
    }

    
Replaces all the occurrences of variables in the given source object with
their matching values from the system properties.
Params:
source –  the source text containing the variables to substitute, null returns null
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables in the given source object with
     * their matching values from the system properties.
     *
     * @param source  the source text containing the variables to substitute, null returns null
     * @return the result of the replace operation
     */
    public static String replaceSystemProperties(Object source) {
        return new StrSubstitutor(StrLookup.systemPropertiesLookup()).replace(source);
    }

    //-----------------------------------------------------------------------
    
Creates a new instance with defaults for variable prefix and suffix
and the escaping character.
/**
     * Creates a new instance with defaults for variable prefix and suffix
     * and the escaping character.
     */
    public StrSubstitutor() {
        this((StrLookup) null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
    }

    
Creates a new instance and initializes it. Uses defaults for variable
prefix and suffix and the escaping character.
Params:
valueMap –  the map with the variables' values, may be null/**
     * Creates a new instance and initializes it. Uses defaults for variable
     * prefix and suffix and the escaping character.
     *
     * @param valueMap  the map with the variables' values, may be null
     */
    public StrSubstitutor(Map valueMap) {
        this(StrLookup.mapLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
    }

    
Creates a new instance and initializes it. Uses a default escaping character.
Params:
valueMap –  the map with the variables' values, may be null
prefix –  the prefix for variables, not null
suffix –  the suffix for variables, not null
Throws:
IllegalArgumentException – if the prefix or suffix is null/**
     * Creates a new instance and initializes it. Uses a default escaping character.
     *
     * @param valueMap  the map with the variables' values, may be null
     * @param prefix  the prefix for variables, not null
     * @param suffix  the suffix for variables, not null
     * @throws IllegalArgumentException if the prefix or suffix is null
     */
    public StrSubstitutor(Map valueMap, String prefix, String suffix) {
        this(StrLookup.mapLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE);
    }

    
Creates a new instance and initializes it.
Params:
valueMap –  the map with the variables' values, may be null
prefix –  the prefix for variables, not null
suffix –  the suffix for variables, not null
escape –  the escape character
Throws:
IllegalArgumentException – if the prefix or suffix is null/**
     * Creates a new instance and initializes it.
     *
     * @param valueMap  the map with the variables' values, may be null
     * @param prefix  the prefix for variables, not null
     * @param suffix  the suffix for variables, not null
     * @param escape  the escape character
     * @throws IllegalArgumentException if the prefix or suffix is null
     */
    public StrSubstitutor(Map valueMap, String prefix, String suffix, char escape) {
        this(StrLookup.mapLookup(valueMap), prefix, suffix, escape);
    }

    
Creates a new instance and initializes it.
Params:
variableResolver –  the variable resolver, may be null/**
     * Creates a new instance and initializes it.
     *
     * @param variableResolver  the variable resolver, may be null
     */
    public StrSubstitutor(StrLookup variableResolver) {
        this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
    }

    
Creates a new instance and initializes it.
Params:
variableResolver –  the variable resolver, may be null
prefix –  the prefix for variables, not null
suffix –  the suffix for variables, not null
escape –  the escape character
Throws:
IllegalArgumentException – if the prefix or suffix is null/**
     * Creates a new instance and initializes it.
     *
     * @param variableResolver  the variable resolver, may be null
     * @param prefix  the prefix for variables, not null
     * @param suffix  the suffix for variables, not null
     * @param escape  the escape character
     * @throws IllegalArgumentException if the prefix or suffix is null
     */
    public StrSubstitutor(StrLookup variableResolver, String prefix, String suffix, char escape) {
        this.setVariableResolver(variableResolver);
        this.setVariablePrefix(prefix);
        this.setVariableSuffix(suffix);
        this.setEscapeChar(escape);
    }

    
Creates a new instance and initializes it.
Params:
variableResolver –  the variable resolver, may be null
prefixMatcher –  the prefix for variables, not null
suffixMatcher –  the suffix for variables, not null
escape –  the escape character
Throws:
IllegalArgumentException – if the prefix or suffix is null/**
     * Creates a new instance and initializes it.
     *
     * @param variableResolver  the variable resolver, may be null
     * @param prefixMatcher  the prefix for variables, not null
     * @param suffixMatcher  the suffix for variables, not null
     * @param escape  the escape character
     * @throws IllegalArgumentException if the prefix or suffix is null
     */
    public StrSubstitutor(
            StrLookup variableResolver, StrMatcher prefixMatcher, StrMatcher suffixMatcher, char escape) {
        this.setVariableResolver(variableResolver);
        this.setVariablePrefixMatcher(prefixMatcher);
        this.setVariableSuffixMatcher(suffixMatcher);
        this.setEscapeChar(escape);
    }

    //-----------------------------------------------------------------------
    
Replaces all the occurrences of variables with their matching values
from the resolver using the given source string as a template.
Params:
source –  the string to replace in, null returns null
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables with their matching values
     * from the resolver using the given source string as a template.
     *
     * @param source  the string to replace in, null returns null
     * @return the result of the replace operation
     */
    public String replace(String source) {
        if (source == null) {
            return null;
        }
        StrBuilder buf = new StrBuilder(source);
        if (substitute(buf, 0, source.length()) == false) {
            return source;
        }
        return buf.toString();
    }

    
Replaces all the occurrences of variables with their matching values
from the resolver using the given source string as a template.

Only the specified portion of the string will be processed.
The rest of the string is not processed, and is not returned.
Params:
source –  the string to replace in, null returns null
offset –  the start offset within the array, must be valid
length –  the length within the array to be processed, must be valid
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables with their matching values
     * from the resolver using the given source string as a template.
     * <p>
     * Only the specified portion of the string will be processed.
     * The rest of the string is not processed, and is not returned.
     *
     * @param source  the string to replace in, null returns null
     * @param offset  the start offset within the array, must be valid
     * @param length  the length within the array to be processed, must be valid
     * @return the result of the replace operation
     */
    public String replace(String source, int offset, int length) {
        if (source == null) {
            return null;
        }
        StrBuilder buf = new StrBuilder(length).append(source, offset, length);
        if (substitute(buf, 0, length) == false) {
            return source.substring(offset, offset + length);
        }
        return buf.toString();
    }

    //-----------------------------------------------------------------------
    
Replaces all the occurrences of variables with their matching values
from the resolver using the given source array as a template.
The array is not altered by this method.
Params:
source –  the character array to replace in, not altered, null returns null
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables with their matching values
     * from the resolver using the given source array as a template.
     * The array is not altered by this method.
     *
     * @param source  the character array to replace in, not altered, null returns null
     * @return the result of the replace operation
     */
    public String replace(char[] source) {
        if (source == null) {
            return null;
        }
        StrBuilder buf = new StrBuilder(source.length).append(source);
        substitute(buf, 0, source.length);
        return buf.toString();
    }

    
Replaces all the occurrences of variables with their matching values
from the resolver using the given source array as a template.
The array is not altered by this method.

Only the specified portion of the array will be processed.
The rest of the array is not processed, and is not returned.
Params:
source –  the character array to replace in, not altered, null returns null
offset –  the start offset within the array, must be valid
length –  the length within the array to be processed, must be valid
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables with their matching values
     * from the resolver using the given source array as a template.
     * The array is not altered by this method.
     * <p>
     * Only the specified portion of the array will be processed.
     * The rest of the array is not processed, and is not returned.
     *
     * @param source  the character array to replace in, not altered, null returns null
     * @param offset  the start offset within the array, must be valid
     * @param length  the length within the array to be processed, must be valid
     * @return the result of the replace operation
     */
    public String replace(char[] source, int offset, int length) {
        if (source == null) {
            return null;
        }
        StrBuilder buf = new StrBuilder(length).append(source, offset, length);
        substitute(buf, 0, length);
        return buf.toString();
    }

    //-----------------------------------------------------------------------
    
Replaces all the occurrences of variables with their matching values
from the resolver using the given source buffer as a template.
The buffer is not altered by this method.
Params:
source –  the buffer to use as a template, not changed, null returns null
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables with their matching values
     * from the resolver using the given source buffer as a template.
     * The buffer is not altered by this method.
     *
     * @param source  the buffer to use as a template, not changed, null returns null
     * @return the result of the replace operation
     */
    public String replace(StringBuffer source) {
        if (source == null) {
            return null;
        }
        StrBuilder buf = new StrBuilder(source.length()).append(source);
        substitute(buf, 0, buf.length());
        return buf.toString();
    }

    
Replaces all the occurrences of variables with their matching values
from the resolver using the given source buffer as a template.
The buffer is not altered by this method.

Only the specified portion of the buffer will be processed.
The rest of the buffer is not processed, and is not returned.
Params:
source –  the buffer to use as a template, not changed, null returns null
offset –  the start offset within the array, must be valid
length –  the length within the array to be processed, must be valid
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables with their matching values
     * from the resolver using the given source buffer as a template.
     * The buffer is not altered by this method.
     * <p>
     * Only the specified portion of the buffer will be processed.
     * The rest of the buffer is not processed, and is not returned.
     *
     * @param source  the buffer to use as a template, not changed, null returns null
     * @param offset  the start offset within the array, must be valid
     * @param length  the length within the array to be processed, must be valid
     * @return the result of the replace operation
     */
    public String replace(StringBuffer source, int offset, int length) {
        if (source == null) {
            return null;
        }
        StrBuilder buf = new StrBuilder(length).append(source, offset, length);
        substitute(buf, 0, length);
        return buf.toString();
    }

    //-----------------------------------------------------------------------
    
Replaces all the occurrences of variables with their matching values
from the resolver using the given source builder as a template.
The builder is not altered by this method.
Params:
source –  the builder to use as a template, not changed, null returns null
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables with their matching values
     * from the resolver using the given source builder as a template.
     * The builder is not altered by this method.
     *
     * @param source  the builder to use as a template, not changed, null returns null
     * @return the result of the replace operation
     */
    public String replace(StrBuilder source) {
        if (source == null) {
            return null;
        }
        StrBuilder buf = new StrBuilder(source.length()).append(source);
        substitute(buf, 0, buf.length());
        return buf.toString();
    }

    
Replaces all the occurrences of variables with their matching values
from the resolver using the given source builder as a template.
The builder is not altered by this method.

Only the specified portion of the builder will be processed.
The rest of the builder is not processed, and is not returned.
Params:
source –  the builder to use as a template, not changed, null returns null
offset –  the start offset within the array, must be valid
length –  the length within the array to be processed, must be valid
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables with their matching values
     * from the resolver using the given source builder as a template.
     * The builder is not altered by this method.
     * <p>
     * Only the specified portion of the builder will be processed.
     * The rest of the builder is not processed, and is not returned.
     *
     * @param source  the builder to use as a template, not changed, null returns null
     * @param offset  the start offset within the array, must be valid
     * @param length  the length within the array to be processed, must be valid
     * @return the result of the replace operation
     */
    public String replace(StrBuilder source, int offset, int length) {
        if (source == null) {
            return null;
        }
        StrBuilder buf = new StrBuilder(length).append(source, offset, length);
        substitute(buf, 0, length);
        return buf.toString();
    }

    //-----------------------------------------------------------------------
    
Replaces all the occurrences of variables in the given source object with
their matching values from the resolver. The input source object is
converted to a string using toString and is not altered.
Params:
source –  the source to replace in, null returns null
Returns:
the result of the replace operation/**
     * Replaces all the occurrences of variables in the given source object with
     * their matching values from the resolver. The input source object is
     * converted to a string using <code>toString</code> and is not altered.
     *
     * @param source  the source to replace in, null returns null
     * @return the result of the replace operation
     */
    public String replace(Object source) {
        if (source == null) {
            return null;
        }
        StrBuilder buf = new StrBuilder().append(source);
        substitute(buf, 0, buf.length());
        return buf.toString();
    }

    //-----------------------------------------------------------------------
    
Replaces all the occurrences of variables within the given source buffer
with their matching values from the resolver.
The buffer is updated with the result.
Params:
source –  the buffer to replace in, updated, null returns zero
Returns:
true if altered/**
     * Replaces all the occurrences of variables within the given source buffer
     * with their matching values from the resolver.
     * The buffer is updated with the result.
     *
     * @param source  the buffer to replace in, updated, null returns zero
     * @return true if altered
     */
    public boolean replaceIn(StringBuffer source) {
        if (source == null) {
            return false;
        }
        return replaceIn(source, 0, source.length());
    }

    
Replaces all the occurrences of variables within the given source buffer
with their matching values from the resolver.
The buffer is updated with the result.

Only the specified portion of the buffer will be processed.
The rest of the buffer is not processed, but it is not deleted.
Params:
source –  the buffer to replace in, updated, null returns zero
offset –  the start offset within the array, must be valid
length –  the length within the buffer to be processed, must be valid
Returns:
true if altered/**
     * Replaces all the occurrences of variables within the given source buffer
     * with their matching values from the resolver.
     * The buffer is updated with the result.
     * <p>
     * Only the specified portion of the buffer will be processed.
     * The rest of the buffer is not processed, but it is not deleted.
     *
     * @param source  the buffer to replace in, updated, null returns zero
     * @param offset  the start offset within the array, must be valid
     * @param length  the length within the buffer to be processed, must be valid
     * @return true if altered
     */
    public boolean replaceIn(StringBuffer source, int offset, int length) {
        if (source == null) {
            return false;
        }
        StrBuilder buf = new StrBuilder(length).append(source, offset, length);
        if (substitute(buf, 0, length) == false) {
            return false;
        }
        source.replace(offset, offset + length, buf.toString());
        return true;
    }

    //-----------------------------------------------------------------------
    
Replaces all the occurrences of variables within the given source
builder with their matching values from the resolver.
Params:
source –  the builder to replace in, updated, null returns zero
Returns:
true if altered/**
     * Replaces all the occurrences of variables within the given source
     * builder with their matching values from the resolver.
     *
     * @param source  the builder to replace in, updated, null returns zero
     * @return true if altered
     */
    public boolean replaceIn(StrBuilder source) {
        if (source == null) {
            return false;
        }
        return substitute(source, 0, source.length());
    }

    
Replaces all the occurrences of variables within the given source
builder with their matching values from the resolver.

Only the specified portion of the builder will be processed.
The rest of the builder is not processed, but it is not deleted.
Params:
source –  the builder to replace in, null returns zero
offset –  the start offset within the array, must be valid
length –  the length within the builder to be processed, must be valid
Returns:
true if altered/**
     * Replaces all the occurrences of variables within the given source
     * builder with their matching values from the resolver.
     * <p>
     * Only the specified portion of the builder will be processed.
     * The rest of the builder is not processed, but it is not deleted.
     *
     * @param source  the builder to replace in, null returns zero
     * @param offset  the start offset within the array, must be valid
     * @param length  the length within the builder to be processed, must be valid
     * @return true if altered
     */
    public boolean replaceIn(StrBuilder source, int offset, int length) {
        if (source == null) {
            return false;
        }
        return substitute(source, offset, length);
    }

    //-----------------------------------------------------------------------
    
Internal method that substitutes the variables.

Most users of this class do not need to call this method. This method will
be called automatically by another (public) method.

Writers of subclasses can override this method if they need access to
the substitution process at the start or end.
Params:
buf –  the string builder to substitute into, not null
offset –  the start offset within the builder, must be valid
length –  the length within the builder to be processed, must be valid
Returns:
true if altered/**
     * Internal method that substitutes the variables.
     * <p>
     * Most users of this class do not need to call this method. This method will
     * be called automatically by another (public) method.
     * <p>
     * Writers of subclasses can override this method if they need access to
     * the substitution process at the start or end.
     *
     * @param buf  the string builder to substitute into, not null
     * @param offset  the start offset within the builder, must be valid
     * @param length  the length within the builder to be processed, must be valid
     * @return true if altered
     */
    protected boolean substitute(StrBuilder buf, int offset, int length) {
        return substitute(buf, offset, length, null) > 0;
    }

    
Recursive handler for multiple levels of interpolation. This is the main
interpolation method, which resolves the values of all variable references
contained in the passed in text.
Params:
buf –  the string builder to substitute into, not null
offset –  the start offset within the builder, must be valid
length –  the length within the builder to be processed, must be valid
priorVariables –  the stack keeping track of the replaced variables, may be null
Returns:
the length change that occurs, unless priorVariables is null when the int
 represents a boolean flag as to whether any change occurred./**
     * Recursive handler for multiple levels of interpolation. This is the main
     * interpolation method, which resolves the values of all variable references
     * contained in the passed in text.
     *
     * @param buf  the string builder to substitute into, not null
     * @param offset  the start offset within the builder, must be valid
     * @param length  the length within the builder to be processed, must be valid
     * @param priorVariables  the stack keeping track of the replaced variables, may be null
     * @return the length change that occurs, unless priorVariables is null when the int
     *  represents a boolean flag as to whether any change occurred.
     */
    private int substitute(StrBuilder buf, int offset, int length, List priorVariables) {
        StrMatcher prefixMatcher = getVariablePrefixMatcher();
        StrMatcher suffixMatcher = getVariableSuffixMatcher();
        char escape = getEscapeChar();

        boolean top = (priorVariables == null);
        boolean altered = false;
        int lengthChange = 0;
        char[] chars = buf.buffer;
        int bufEnd = offset + length;
        int pos = offset;
        while (pos < bufEnd) {
            int startMatchLen = prefixMatcher.isMatch(chars, pos, offset,
                    bufEnd);
            if (startMatchLen == 0) {
                pos++;
            } else {
                // found variable start marker
                if (pos > offset && chars[pos - 1] == escape) {
                    // escaped
                    buf.deleteCharAt(pos - 1);
                    chars = buf.buffer; // in case buffer was altered
                    lengthChange--;
                    altered = true;
                    bufEnd--;
                } else {
                    // find suffix
                    int startPos = pos;
                    pos += startMatchLen;
                    int endMatchLen = 0;
                    int nestedVarCount = 0;
                    while (pos < bufEnd) {
                        if (isEnableSubstitutionInVariables()
                                && (endMatchLen = prefixMatcher.isMatch(chars,
                                        pos, offset, bufEnd)) != 0) {
                            // found a nested variable start
                            nestedVarCount++;
                            pos += endMatchLen;
                            continue;
                        }

                        endMatchLen = suffixMatcher.isMatch(chars, pos, offset,
                                bufEnd);
                        if (endMatchLen == 0) {
                            pos++;
                        } else {
                            // found variable end marker
                            if (nestedVarCount == 0) {
                                String varName = new String(chars, startPos
                                        + startMatchLen, pos - startPos
                                        - startMatchLen);
                                if (isEnableSubstitutionInVariables()) {
                                    StrBuilder bufName = new StrBuilder(varName);
                                    substitute(bufName, 0, bufName.length());
                                    varName = bufName.toString();
                                }
                                pos += endMatchLen;
                                int endPos = pos;

                                // on the first call initialize priorVariables
                                if (priorVariables == null) {
                                    priorVariables = new ArrayList();
                                    priorVariables.add(new String(chars,
                                            offset, length));
                                }

                                // handle cyclic substitution
                                checkCyclicSubstitution(varName, priorVariables);
                                priorVariables.add(varName);

                                // resolve the variable
                                String varValue = resolveVariable(varName, buf,
                                        startPos, endPos);
                                if (varValue != null) {
                                    // recursive replace
                                    int varLen = varValue.length();
                                    buf.replace(startPos, endPos, varValue);
                                    altered = true;
                                    int change = substitute(buf, startPos,
                                            varLen, priorVariables);
                                    change = change
                                            + (varLen - (endPos - startPos));
                                    pos += change;
                                    bufEnd += change;
                                    lengthChange += change;
                                    chars = buf.buffer; // in case buffer was
                                                        // altered
                                }

                                // remove variable from the cyclic stack
                                priorVariables
                                        .remove(priorVariables.size() - 1);
                                break;
                            } else {
                                nestedVarCount--;
                                pos += endMatchLen;
                            }
                        }
                    }
                }
            }
        }
        if (top) {
            return (altered ? 1 : 0);
        }
        return lengthChange;
    }

    
Checks if the specified variable is already in the stack (list) of variables.
Params:
varName –  the variable name to check
priorVariables –  the list of prior variables/**
     * Checks if the specified variable is already in the stack (list) of variables.
     *
     * @param varName  the variable name to check
     * @param priorVariables  the list of prior variables
     */
    private void checkCyclicSubstitution(String varName, List priorVariables) {
        if (priorVariables.contains(varName) == false) {
            return;
        }
        StrBuilder buf = new StrBuilder(256);
        buf.append("Infinite loop in property interpolation of ");
        buf.append(priorVariables.remove(0));
        buf.append(": ");
        buf.appendWithSeparators(priorVariables, "->");
        throw new IllegalStateException(buf.toString());
    }

    
Internal method that resolves the value of a variable.

Most users of this class do not need to call this method. This method is
called automatically by the substitution process.
 Writers of subclasses can override this method if they need to alter how each substitution occurs. The method is passed the variable's name and must return the corresponding value. This implementation uses the getVariableResolver() with the variable's name as the key. 
Params:
variableName –  the name of the variable, not null
buf –  the buffer where the substitution is occurring, not null
startPos –  the start position of the variable including the prefix, valid
endPos –  the end position of the variable including the suffix, valid
Returns:
the variable's value or null if the variable is unknown/**
     * Internal method that resolves the value of a variable.
     * <p>
     * Most users of this class do not need to call this method. This method is
     * called automatically by the substitution process.
     * <p>
     * Writers of subclasses can override this method if they need to alter
     * how each substitution occurs. The method is passed the variable's name
     * and must return the corresponding value. This implementation uses the
     * {@link #getVariableResolver()} with the variable's name as the key.
     *
     * @param variableName  the name of the variable, not null
     * @param buf  the buffer where the substitution is occurring, not null
     * @param startPos  the start position of the variable including the prefix, valid
     * @param endPos  the end position of the variable including the suffix, valid
     * @return the variable's value or <b>null</b> if the variable is unknown
     */
    protected String resolveVariable(String variableName, StrBuilder buf, int startPos, int endPos) {
        StrLookup resolver = getVariableResolver();
        if (resolver == null) {
            return null;
        }
        return resolver.lookup(variableName);
    }

    // Escape
    //-----------------------------------------------------------------------
    
Returns the escape character.
Returns:
the character used for escaping variable references/**
     * Returns the escape character.
     *
     * @return the character used for escaping variable references
     */
    public char getEscapeChar() {
        return this.escapeChar;
    }

    
Sets the escape character.
If this character is placed before a variable reference in the source
text, this variable will be ignored.
Params:
escapeCharacter –  the escape character (0 for disabling escaping)/**
     * Sets the escape character.
     * If this character is placed before a variable reference in the source
     * text, this variable will be ignored.
     *
     * @param escapeCharacter  the escape character (0 for disabling escaping)
     */
    public void setEscapeChar(char escapeCharacter) {
        this.escapeChar = escapeCharacter;
    }

    // Prefix
    //-----------------------------------------------------------------------
    
Gets the variable prefix matcher currently in use.

The variable prefix is the characer or characters that identify the
start of a variable. This prefix is expressed in terms of a matcher
allowing advanced prefix matches.
Returns:
the prefix matcher in use/**
     * Gets the variable prefix matcher currently in use.
     * <p>
     * The variable prefix is the characer or characters that identify the
     * start of a variable. This prefix is expressed in terms of a matcher
     * allowing advanced prefix matches.
     *
     * @return the prefix matcher in use
     */
    public StrMatcher getVariablePrefixMatcher() {
        return prefixMatcher;
    }

    
Sets the variable prefix matcher currently in use.

The variable prefix is the characer or characters that identify the
start of a variable. This prefix is expressed in terms of a matcher
allowing advanced prefix matches.
Params:
prefixMatcher –  the prefix matcher to use, null ignored
Throws:
IllegalArgumentException – if the prefix matcher is null
Returns:
this, to enable chaining/**
     * Sets the variable prefix matcher currently in use.
     * <p>
     * The variable prefix is the characer or characters that identify the
     * start of a variable. This prefix is expressed in terms of a matcher
     * allowing advanced prefix matches.
     *
     * @param prefixMatcher  the prefix matcher to use, null ignored
     * @return this, to enable chaining
     * @throws IllegalArgumentException if the prefix matcher is null
     */
    public StrSubstitutor setVariablePrefixMatcher(StrMatcher prefixMatcher) {
        if (prefixMatcher == null) {
            throw new IllegalArgumentException("Variable prefix matcher must not be null!");
        }
        this.prefixMatcher = prefixMatcher;
        return this;
    }

    
Sets the variable prefix to use.

The variable prefix is the character or characters that identify the
start of a variable. This method allows a single character prefix to
be easily set.
Params:
prefix –  the prefix character to use
Returns:
this, to enable chaining/**
     * Sets the variable prefix to use.
     * <p>
     * The variable prefix is the character or characters that identify the
     * start of a variable. This method allows a single character prefix to
     * be easily set.
     *
     * @param prefix  the prefix character to use
     * @return this, to enable chaining
     */
    public StrSubstitutor setVariablePrefix(char prefix) {
        return setVariablePrefixMatcher(StrMatcher.charMatcher(prefix));
    }

    
Sets the variable prefix to use.

The variable prefix is the characer or characters that identify the
start of a variable. This method allows a string prefix to be easily set.
Params:
prefix –  the prefix for variables, not null
Throws:
IllegalArgumentException – if the prefix is null
Returns:
this, to enable chaining/**
     * Sets the variable prefix to use.
     * <p>
     * The variable prefix is the characer or characters that identify the
     * start of a variable. This method allows a string prefix to be easily set.
     *
     * @param prefix  the prefix for variables, not null
     * @return this, to enable chaining
     * @throws IllegalArgumentException if the prefix is null
     */
    public StrSubstitutor setVariablePrefix(String prefix) {
       if (prefix == null) {
            throw new IllegalArgumentException("Variable prefix must not be null!");
        }
        return setVariablePrefixMatcher(StrMatcher.stringMatcher(prefix));
    }

    // Suffix
    //-----------------------------------------------------------------------
    
Gets the variable suffix matcher currently in use.

The variable suffix is the characer or characters that identify the
end of a variable. This suffix is expressed in terms of a matcher
allowing advanced suffix matches.
Returns:
the suffix matcher in use/**
     * Gets the variable suffix matcher currently in use.
     * <p>
     * The variable suffix is the characer or characters that identify the
     * end of a variable. This suffix is expressed in terms of a matcher
     * allowing advanced suffix matches.
     *
     * @return the suffix matcher in use
     */
    public StrMatcher getVariableSuffixMatcher() {
        return suffixMatcher;
    }

    
Sets the variable suffix matcher currently in use.

The variable suffix is the characer or characters that identify the
end of a variable. This suffix is expressed in terms of a matcher
allowing advanced suffix matches.
Params:
suffixMatcher –  the suffix matcher to use, null ignored
Throws:
IllegalArgumentException – if the suffix matcher is null
Returns:
this, to enable chaining/**
     * Sets the variable suffix matcher currently in use.
     * <p>
     * The variable suffix is the characer or characters that identify the
     * end of a variable. This suffix is expressed in terms of a matcher
     * allowing advanced suffix matches.
     *
     * @param suffixMatcher  the suffix matcher to use, null ignored
     * @return this, to enable chaining
     * @throws IllegalArgumentException if the suffix matcher is null
     */
    public StrSubstitutor setVariableSuffixMatcher(StrMatcher suffixMatcher) {
        if (suffixMatcher == null) {
            throw new IllegalArgumentException("Variable suffix matcher must not be null!");
        }
        this.suffixMatcher = suffixMatcher;
        return this;
    }

    
Sets the variable suffix to use.

The variable suffix is the characer or characters that identify the
end of a variable. This method allows a single character suffix to
be easily set.
Params:
suffix –  the suffix character to use
Returns:
this, to enable chaining/**
     * Sets the variable suffix to use.
     * <p>
     * The variable suffix is the characer or characters that identify the
     * end of a variable. This method allows a single character suffix to
     * be easily set.
     *
     * @param suffix  the suffix character to use
     * @return this, to enable chaining
     */
    public StrSubstitutor setVariableSuffix(char suffix) {
        return setVariableSuffixMatcher(StrMatcher.charMatcher(suffix));
    }

    
Sets the variable suffix to use.

The variable suffix is the character or characters that identify the
end of a variable. This method allows a string suffix to be easily set.
Params:
suffix –  the suffix for variables, not null
Throws:
IllegalArgumentException – if the suffix is null
Returns:
this, to enable chaining/**
     * Sets the variable suffix to use.
     * <p>
     * The variable suffix is the character or characters that identify the
     * end of a variable. This method allows a string suffix to be easily set.
     *
     * @param suffix  the suffix for variables, not null
     * @return this, to enable chaining
     * @throws IllegalArgumentException if the suffix is null
     */
    public StrSubstitutor setVariableSuffix(String suffix) {
       if (suffix == null) {
            throw new IllegalArgumentException("Variable suffix must not be null!");
        }
        return setVariableSuffixMatcher(StrMatcher.stringMatcher(suffix));
    }

    // Resolver
    //-----------------------------------------------------------------------
    
Gets the VariableResolver that is used to lookup variables.
Returns:
the VariableResolver/**
     * Gets the VariableResolver that is used to lookup variables.
     *
     * @return the VariableResolver
     */
    public StrLookup getVariableResolver() {
        return this.variableResolver;
    }

    
Sets the VariableResolver that is used to lookup variables.
Params:
variableResolver –  the VariableResolver/**
     * Sets the VariableResolver that is used to lookup variables.
     *
     * @param variableResolver  the VariableResolver
     */
    public void setVariableResolver(StrLookup variableResolver) {
        this.variableResolver = variableResolver;
    }

    // Substitution support in variable names
    //-----------------------------------------------------------------------
    
Returns a flag whether substitution is done in variable names.
Returns:
the substitution in variable names flag
Since:
2.6/**
     * Returns a flag whether substitution is done in variable names.
     *
     * @return the substitution in variable names flag
     * @since 2.6
     */
    public boolean isEnableSubstitutionInVariables() {
        return enableSubstitutionInVariables;
    }

    
Sets a flag whether substitution is done in variable names. If set to
true, the names of variables can contain other variables which are
processed first before the original variable is evaluated, e.g.
${jre-${java.version}}. The default value is false.
Params:
enableSubstitutionInVariables – the new value of the flag
Since:
2.6/**
     * Sets a flag whether substitution is done in variable names. If set to
     * <b>true</b>, the names of variables can contain other variables which are
     * processed first before the original variable is evaluated, e.g.
     * <code>${jre-${java.version}}</code>. The default value is <b>false</b>.
     *
     * @param enableSubstitutionInVariables the new value of the flag
     * @since 2.6
     */
    public void setEnableSubstitutionInVariables(
            boolean enableSubstitutionInVariables) {
        this.enableSubstitutionInVariables = enableSubstitutionInVariables;
    }
}