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/*
 * 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.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;

import org.apache.commons.lang3.Validate;
import org.apache.commons.text.lookup.StringLookup;
import org.apache.commons.text.lookup.StringLookupFactory;
import org.apache.commons.text.matcher.StringMatcher;
import org.apache.commons.text.matcher.StringMatcherFactory;

/**
 * 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: * *

 * StringSubstitutor
 *         .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}.";
 * StringSubstitutor sub = new StringSubstitutor(valuesMap);
 * String resolvedString = sub.replace(templateString);
 * 
* * yielding: * *
 *      The quick brown fox jumped over the lazy dog.
 * 
*

* Also, this class allows to set a default value for unresolved variables. The default value for a variable can be * appended to the variable name after the variable default value delimiter. The default value of the variable default * value delimiter is ':-', as in bash and other *nix shells, as those are arguably where the default ${} delimiter set * originated. The variable default value delimiter can be manually set by calling * {@link #setValueDelimiterMatcher(StringMatcher)}, {@link #setValueDelimiter(char)} or * {@link #setValueDelimiter(String)}. The following shows an example with variable default value settings: * *

 * Map valuesMap = HashMap();
 * valuesMap.put("animal", "quick brown fox");
 * valuesMap.put("target", "lazy dog");
 * String templateString = "The ${animal} jumped over the ${target}. ${undefined.number:-1234567890}.";
 * StringSubstitutor sub = new StringSubstitutor(valuesMap);
 * String resolvedString = sub.replace(templateString);
 * 
* * yielding: * *
 *      The quick brown fox jumped over the lazy dog. 1234567890.
 * 
*

* 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}}
 * 
* * StringSubstitutor supports this recursive substitution in variable names, but it has to be enabled * explicitly by setting the {@link #setEnableSubstitutionInVariables(boolean) enableSubstitutionInVariables} property * to true. *

* This class is not thread safe. *

* * @since 1.3 */ public class StringSubstitutor { /** * The default variable default separator. * * @since 1.5. */ public static final String DEFAULT_VAR_DEFAULT = ":-"; /** * The default variable end separator. * * @since 1.5. */ public static final String DEFAULT_VAR_END = "}"; /** * The default variable start separator. * * @since 1.5. */ public static final String DEFAULT_VAR_START = "${"; /** * Constant for the default escape character. */ public static final char DEFAULT_ESCAPE = '$'; /** * Constant for the default variable prefix. */ public static final StringMatcher DEFAULT_PREFIX = StringMatcherFactory.INSTANCE.stringMatcher(DEFAULT_VAR_START); /** * Constant for the default variable suffix. */ public static final StringMatcher DEFAULT_SUFFIX = StringMatcherFactory.INSTANCE.stringMatcher(DEFAULT_VAR_END); /** * Constant for the default value delimiter of a variable. */ public static final StringMatcher DEFAULT_VALUE_DELIMITER = StringMatcherFactory.INSTANCE.stringMatcher(DEFAULT_VAR_DEFAULT); // ----------------------------------------------------------------------- /** * Replaces all the occurrences of variables in the given source object with their matching values from the map. * * @param * the type of the values in 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(final Object source, final Map valueMap) { return new StringSubstitutor(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 specify a custom variable prefix and suffix * * @param * the type of the values in 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 * @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(final Object source, final Map valueMap, final String prefix, final String suffix) { return new StringSubstitutor(valueMap, prefix, suffix).replace(source); } /** * 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 */ public static String replace(final Object source, final Properties valueProperties) { if (valueProperties == null) { return source.toString(); } final Map valueMap = new HashMap<>(); final Enumeration propNames = valueProperties.propertyNames(); while (propNames.hasMoreElements()) { final String propName = (String) propNames.nextElement(); final String propValue = valueProperties.getProperty(propName); valueMap.put(propName, propValue); } return StringSubstitutor.replace(source, valueMap); } /** * 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(final Object source) { return new StringSubstitutor(StringLookupFactory.INSTANCE.systemPropertyStringLookup()).replace(source); } /** * Stores the escape character. */ private char escapeChar; /** * Stores the variable prefix. */ private StringMatcher prefixMatcher; /** * Stores the variable suffix. */ private StringMatcher suffixMatcher; /** * Stores the default variable value delimiter. */ private StringMatcher valueDelimiterMatcher; /** * Variable resolution is delegated to an implementor of {@link StringLookup}. */ private StringLookup variableResolver; /** * The flag whether substitution in variable names is enabled. */ private boolean enableSubstitutionInVariables; /** * Whether escapes should be preserved. Default is false; */ private boolean preserveEscapes = false; /** * The flag whether substitution in variable values is disabled. */ private boolean disableSubstitutionInValues; // ----------------------------------------------------------------------- /** * Creates a new instance with defaults for variable prefix and suffix and the escaping character. */ public StringSubstitutor() { this((StringLookup) 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. * * @param * the type of the values in the map * @param valueMap * the map with the variables' values, may be null */ public StringSubstitutor(final Map valueMap) { this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE); } /** * Creates a new instance and initializes it. Uses a default escaping character. * * @param * the type of the values in the map * @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 StringSubstitutor(final Map valueMap, final String prefix, final String suffix) { this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE); } /** * Creates a new instance and initializes it. * * @param * the type of the values in the map * @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 StringSubstitutor(final Map valueMap, final String prefix, final String suffix, final char escape) { this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, escape); } /** * Creates a new instance and initializes it. * * @param * the type of the values in the map * @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 * @param valueDelimiter * the variable default value delimiter, may be null * @throws IllegalArgumentException * if the prefix or suffix is null */ public StringSubstitutor(final Map valueMap, final String prefix, final String suffix, final char escape, final String valueDelimiter) { this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, escape, valueDelimiter); } /** * Creates a new instance and initializes it. * * @param variableResolver * the variable resolver, may be null */ public StringSubstitutor(final StringLookup variableResolver) { this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE); } /** * 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 StringSubstitutor(final StringLookup variableResolver, final String prefix, final String suffix, final char escape) { this.setVariableResolver(variableResolver); this.setVariablePrefix(prefix); this.setVariableSuffix(suffix); this.setEscapeChar(escape); this.setValueDelimiterMatcher(DEFAULT_VALUE_DELIMITER); } /** * 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 * @param valueDelimiter * the variable default value delimiter string, may be null * @throws IllegalArgumentException * if the prefix or suffix is null */ public StringSubstitutor(final StringLookup variableResolver, final String prefix, final String suffix, final char escape, final String valueDelimiter) { this.setVariableResolver(variableResolver); this.setVariablePrefix(prefix); this.setVariableSuffix(suffix); this.setEscapeChar(escape); this.setValueDelimiter(valueDelimiter); } /** * 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 StringSubstitutor(final StringLookup variableResolver, final StringMatcher prefixMatcher, final StringMatcher suffixMatcher, final char escape) { this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER); } /** * 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 * @param valueDelimiterMatcher * the variable default value delimiter matcher, may be null * @throws IllegalArgumentException * if the prefix or suffix is null */ public StringSubstitutor(final StringLookup variableResolver, final StringMatcher prefixMatcher, final StringMatcher suffixMatcher, final char escape, final StringMatcher valueDelimiterMatcher) { this.setVariableResolver(variableResolver); this.setVariablePrefixMatcher(prefixMatcher); this.setVariableSuffixMatcher(suffixMatcher); this.setEscapeChar(escape); this.setValueDelimiterMatcher(valueDelimiterMatcher); } /** * 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(final String varName, final List priorVariables) { if (!priorVariables.contains(varName)) { return; } final TextStringBuilder buf = new TextStringBuilder(256); buf.append("Infinite loop in property interpolation of "); buf.append(priorVariables.remove(0)); buf.append(": "); buf.appendWithSeparators(priorVariables, "->"); throw new IllegalStateException(buf.toString()); } // Escape // ----------------------------------------------------------------------- /** * Returns the escape character. * * @return the character used for escaping variable references */ public char getEscapeChar() { return this.escapeChar; } // Resolver // ----------------------------------------------------------------------- /** * Gets the StringLookup that is used to lookup variables. * * @return the StringLookup */ public StringLookup getStringLookup() { return this.variableResolver; } // Variable Default Value Delimiter // ----------------------------------------------------------------------- /** * Gets the variable default value delimiter matcher currently in use. *

* The variable default value delimiter is the character or characters that delimite the variable name and the * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default * value delimiter matches. *

* If it returns null, then the variable default value resolution is disabled. * * @return the variable default value delimiter matcher in use, may be null */ public StringMatcher getValueDelimiterMatcher() { return valueDelimiterMatcher; } // Prefix // ----------------------------------------------------------------------- /** * Gets the variable prefix matcher currently in use. *

* The variable prefix is the character 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 StringMatcher getVariablePrefixMatcher() { return prefixMatcher; } // Suffix // ----------------------------------------------------------------------- /** * Gets the variable suffix matcher currently in use. *

* The variable suffix is the character 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 StringMatcher getVariableSuffixMatcher() { return suffixMatcher; } /** * Returns a flag whether substitution is disabled in variable values.If set to true, the values of variables * can contain other variables will not be processed and substituted original variable is evaluated, e.g. * *

     * Map valuesMap = HashMap();
     * valuesMap.put("name", "Douglas ${surname}");
     * valuesMap.put("surname", "Crockford");
     * String templateString = "Hi ${name}";
     * StrSubstitutor sub = new StrSubstitutor(valuesMap);
     * String resolvedString = sub.replace(templateString);
     * 
* * yielding: * *
     *      Hi Douglas ${surname}
     * 
* * @return the substitution in variable values flag */ public boolean isDisableSubstitutionInValues() { return disableSubstitutionInValues; } // Substitution support in variable names // ----------------------------------------------------------------------- /** * Returns a flag whether substitution is done in variable names. * * @return the substitution in variable names flag */ public boolean isEnableSubstitutionInVariables() { return enableSubstitutionInVariables; } /** * Returns the flag controlling whether escapes are preserved during substitution. * * @return the preserve escape flag */ public boolean isPreserveEscapes() { return preserveEscapes; } // ----------------------------------------------------------------------- /** * 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(final char[] source) { if (source == null) { return null; } final TextStringBuilder buf = new TextStringBuilder(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. * * @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(final char[] source, final int offset, final int length) { if (source == null) { return null; } final TextStringBuilder buf = new TextStringBuilder(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 as * a template. The source 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(final CharSequence source) { if (source == null) { return null; } return replace(source, 0, source.length()); } /** * Replaces all the occurrences of variables with their matching values from the resolver using the given source as * a template. The source 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. * * @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(final CharSequence source, final int offset, final int length) { if (source == null) { return null; } final TextStringBuilder buf = new TextStringBuilder(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. * * @param source * the source to replace in, null returns null * @return the result of the replace operation */ public String replace(final Object source) { if (source == null) { return null; } final TextStringBuilder buf = new TextStringBuilder().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. * * @param source * the builder to use as a template, not changed, null returns null * @return the result of the replace operation */ public String replace(final TextStringBuilder source) { if (source == null) { return null; } final TextStringBuilder buf = new TextStringBuilder(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. * * @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(final TextStringBuilder source, final int offset, final int length) { if (source == null) { return null; } final TextStringBuilder buf = new TextStringBuilder(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 * string as a template. * * @param source * the string to replace in, null returns null * @return the result of the replace operation */ public String replace(final String source) { if (source == null) { return null; } final TextStringBuilder buf = new TextStringBuilder(source); if (!substitute(buf, 0, source.length())) { 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. * * @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(final String source, final int offset, final int length) { if (source == null) { return null; } final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); if (!substitute(buf, 0, length)) { 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 * 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(final StringBuffer source) { if (source == null) { return null; } final TextStringBuilder buf = new TextStringBuilder(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. * * @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(final StringBuffer source, final int offset, final int length) { if (source == null) { return null; } final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); substitute(buf, 0, length); return buf.toString(); } // ----------------------------------------------------------------------- /** * 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(final TextStringBuilder 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. * * @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(final TextStringBuilder source, final int offset, final int length) { if (source == null) { return false; } return substitute(source, offset, 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. * * @param source * the buffer to replace in, updated, null returns zero * @return true if altered */ public boolean replaceIn(final 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. * * @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(final StringBuffer source, final int offset, final int length) { if (source == null) { return false; } final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); if (!substitute(buf, 0, length)) { return false; } source.replace(offset, offset + length, buf.toString()); return true; } // ----------------------------------------------------------------------- /** * 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(final StringBuilder source) { if (source == null) { return false; } return replaceIn(source, 0, source.length()); } /** * Replaces all the occurrences of variables within the given source builder with their matching values from the * resolver. The builder 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. * * @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(final StringBuilder source, final int offset, final int length) { if (source == null) { return false; } final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); if (!substitute(buf, 0, length)) { return false; } source.replace(offset, offset + length, buf.toString()); return true; } /** * 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 * {@link #getStringLookup()} 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 null if the variable is unknown */ protected String resolveVariable(final String variableName, final TextStringBuilder buf, final int startPos, final int endPos) { final StringLookup resolver = getStringLookup(); if (resolver == null) { return null; } return resolver.lookup(variableName); } /** * Sets a flag whether substitution is done in variable values (recursive). * * @param disableSubstitutionInValues * true if substitution in variable value are disabled * @return this, to enable chaining */ public StringSubstitutor setDisableSubstitutionInValues(final boolean disableSubstitutionInValues) { this.disableSubstitutionInValues = disableSubstitutionInValues; return this; } /** * 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. * * @param enableSubstitutionInVariables * the new value of the flag * @return this, to enable chaining */ public StringSubstitutor setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) { this.enableSubstitutionInVariables = enableSubstitutionInVariables; return this; } /** * 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) * @return this, to enable chaining */ public StringSubstitutor setEscapeChar(final char escapeCharacter) { this.escapeChar = escapeCharacter; return this; } /** * Sets a flag controlling whether escapes are preserved during substitution. If set to true, the escape * character is retained during substitution (e.g. $${this-is-escaped} remains * $${this-is-escaped}). If set to false, the escape character is removed during substitution * (e.g. $${this-is-escaped} becomes ${this-is-escaped}). The default value is * false * * @param preserveEscapes * true if escapes are to be preserved * @return this, to enable chaining */ public StringSubstitutor setPreserveEscapes(final boolean preserveEscapes) { this.preserveEscapes = preserveEscapes; return this; } /** * Sets the variable default value delimiter to use. *

* The variable default value delimiter is the character or characters that delimite the variable name and the * variable default value. This method allows a single character variable default value delimiter to be easily set. * * @param valueDelimiter * the variable default value delimiter character to use * @return this, to enable chaining */ public StringSubstitutor setValueDelimiter(final char valueDelimiter) { return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.charMatcher(valueDelimiter)); } /** * Sets the variable default value delimiter to use. *

* The variable default value delimiter is the character or characters that delimite the variable name and the * variable default value. This method allows a string variable default value delimiter to be easily set. *

* If the valueDelimiter is null or empty string, then the variable default value resolution becomes * disabled. * * @param valueDelimiter * the variable default value delimiter string to use, may be null or empty * @return this, to enable chaining */ public StringSubstitutor setValueDelimiter(final String valueDelimiter) { if (valueDelimiter == null || valueDelimiter.length() == 0) { setValueDelimiterMatcher(null); return this; } return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.stringMatcher(valueDelimiter)); } /** * Sets the variable default value delimiter matcher to use. *

* The variable default value delimiter is the character or characters that delimite the variable name and the * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default * value delimiter matches. *

* If the valueDelimiterMatcher is null, then the variable default value resolution becomes disabled. * * @param valueDelimiterMatcher * variable default value delimiter matcher to use, may be null * @return this, to enable chaining */ public StringSubstitutor setValueDelimiterMatcher(final StringMatcher valueDelimiterMatcher) { this.valueDelimiterMatcher = valueDelimiterMatcher; 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. * * @param prefix * the prefix character to use * @return this, to enable chaining */ public StringSubstitutor setVariablePrefix(final char prefix) { return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.charMatcher(prefix)); } /** * 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 * 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 StringSubstitutor setVariablePrefix(final String prefix) { Validate.isTrue(prefix != null, "Variable prefix must not be null!"); return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(prefix)); } /** * Sets the variable prefix matcher currently in use. *

* The variable prefix is the character 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 StringSubstitutor setVariablePrefixMatcher(final StringMatcher prefixMatcher) { Validate.isTrue(prefixMatcher != null, "Variable prefix matcher must not be null!"); this.prefixMatcher = prefixMatcher; return this; } /** * Sets the VariableResolver that is used to lookup variables. * * @param variableResolver * the VariableResolver * @return this, to enable chaining */ public StringSubstitutor setVariableResolver(final StringLookup variableResolver) { this.variableResolver = variableResolver; return this; } /** * 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 * single character suffix to be easily set. * * @param suffix * the suffix character to use * @return this, to enable chaining */ public StringSubstitutor setVariableSuffix(final char suffix) { return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.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. * * @param suffix * the suffix for variables, not null * @return this, to enable chaining * @throws IllegalArgumentException * if the suffix is null */ public StringSubstitutor setVariableSuffix(final String suffix) { Validate.isTrue(suffix != null, "Variable suffix must not be null!"); return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(suffix)); } /** * Sets the variable suffix matcher currently in use. *

* The variable suffix is the character 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 StringSubstitutor setVariableSuffixMatcher(final StringMatcher suffixMatcher) { Validate.isTrue(suffixMatcher != null, "Variable suffix matcher must not be null!"); this.suffixMatcher = suffixMatcher; return this; } // ----------------------------------------------------------------------- /** * 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. * * @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(final TextStringBuilder buf, final int offset, final 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. * * @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(final TextStringBuilder buf, final int offset, final int length, List priorVariables) { final StringMatcher pfxMatcher = getVariablePrefixMatcher(); final StringMatcher suffMatcher = getVariableSuffixMatcher(); final char escape = getEscapeChar(); final StringMatcher valueDelimMatcher = getValueDelimiterMatcher(); final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables(); final boolean substitutionInValuesDisabled = isDisableSubstitutionInValues(); final boolean top = priorVariables == null; boolean altered = false; int lengthChange = 0; char[] chars = buf.buffer; int bufEnd = offset + length; int pos = offset; while (pos < bufEnd) { final int startMatchLen = pfxMatcher.isMatch(chars, pos, offset, bufEnd); if (startMatchLen == 0) { pos++; } else { // found variable start marker if (pos > offset && chars[pos - 1] == escape) { // escaped if (preserveEscapes) { pos++; continue; } buf.deleteCharAt(pos - 1); chars = buf.buffer; // in case buffer was altered lengthChange--; altered = true; bufEnd--; } else { // find suffix final int startPos = pos; pos += startMatchLen; int endMatchLen = 0; int nestedVarCount = 0; while (pos < bufEnd) { if (substitutionInVariablesEnabled && pfxMatcher.isMatch(chars, pos, offset, bufEnd) != 0) { // found a nested variable start endMatchLen = pfxMatcher.isMatch(chars, pos, offset, bufEnd); nestedVarCount++; pos += endMatchLen; continue; } endMatchLen = suffMatcher.isMatch(chars, pos, offset, bufEnd); if (endMatchLen == 0) { pos++; } else { // found variable end marker if (nestedVarCount == 0) { String varNameExpr = new String(chars, startPos + startMatchLen, pos - startPos - startMatchLen); if (substitutionInVariablesEnabled) { final TextStringBuilder bufName = new TextStringBuilder(varNameExpr); substitute(bufName, 0, bufName.length()); varNameExpr = bufName.toString(); } pos += endMatchLen; final int endPos = pos; String varName = varNameExpr; String varDefaultValue = null; if (valueDelimMatcher != null) { final char[] varNameExprChars = varNameExpr.toCharArray(); int valueDelimiterMatchLen = 0; for (int i = 0; i < varNameExprChars.length; i++) { // if there's any nested variable when nested variable substitution disabled, // then stop resolving name and default value. if (!substitutionInVariablesEnabled && pfxMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) { break; } if (valueDelimMatcher.isMatch(varNameExprChars, i, 0, varNameExprChars.length) != 0) { valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i, 0, varNameExprChars.length); varName = varNameExpr.substring(0, i); varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen); break; } } } // 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) { varValue = varDefaultValue; } if (varValue != null) { final int varLen = varValue.length(); buf.replace(startPos, endPos, varValue); altered = true; int change = 0; if (!substitutionInValuesDisabled) { // recursive replace 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; } nestedVarCount--; pos += endMatchLen; } } } } } if (top) { return altered ? 1 : 0; } return lengthChange; } }





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