org.apache.commons.text.StringSubstitutor Maven / Gradle / Ivy
Show all versions of commons-text Show documentation
/*
* 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:
*
*
* 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.
*
*
* 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}.";
* StrSubstitutor sub = new StrSubstitutor(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}}
*
*
* StrSubstitutor 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 {
/**
* 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("${");
/**
* Constant for the default variable suffix.
*/
public static final StringMatcher DEFAULT_SUFFIX = StringMatcherFactory.INSTANCE.stringMatcher("}");
/**
* Constant for the default value delimiter of a variable.
*/
public static final StringMatcher DEFAULT_VALUE_DELIMITER = StringMatcherFactory.INSTANCE.stringMatcher(":-");
// -----------------------------------------------------------------------
/**
* 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;
}
}