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Apache Commons Text is a library focused on algorithms working on strings.
/*
* 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;
/**
* 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 {@code ${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 {@code 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<String, String> valuesMap = new 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(StrMatcher)},
* {@link #setValueDelimiter(char)} or {@link #setValueDelimiter(String)}.
* The following shows an example with variable default value settings:
*
* Map<String, String> valuesMap = new 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 {@code name} variable is {@code 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}}
*
* {@code 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 1.0
* @deprecated Deprecated as of 1.3, use {@link StringSubstitutor} instead. This class will be removed in 2.0.
*/
@Deprecated
public class StrSubstitutor {
/**
* Constant for the default escape character.
*/
public static final char DEFAULT_ESCAPE = '$';
/**
* Constant for the default variable prefix.
*/
public static final StrMatcher DEFAULT_PREFIX = StrMatcher.stringMatcher("${");
/**
* Constant for the default variable suffix.
*/
public static final StrMatcher DEFAULT_SUFFIX = StrMatcher.stringMatcher("}");
/**
* Constant for the default value delimiter of a variable.
*/
public static final StrMatcher DEFAULT_VALUE_DELIMITER = StrMatcher.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 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 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 StrSubstitutor(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.valueOf(propNames.nextElement());
final 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.
*
* @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 StrSubstitutor(StrLookup.systemPropertiesLookup()).replace(source);
}
/**
* Stores the escape character.
*/
private char escapeChar;
/**
* Stores the variable prefix.
*/
private StrMatcher prefixMatcher;
/**
* Stores the variable suffix.
*/
private StrMatcher suffixMatcher;
/**
* Stores the default variable value delimiter.
*/
private StrMatcher valueDelimiterMatcher;
/**
* Variable resolution is delegated to an implementor of VariableResolver.
*/
private StrLookup variableResolver;
/**
* The flag whether substitution in variable names is enabled.
*/
private boolean enableSubstitutionInVariables;
/**
* Whether escapes should be preserved. Default is false;
*/
private boolean preserveEscapes;
/**
* The flag whether substitution in variable values is disabled.
*/
private boolean disableSubstitutionInValues;
/**
* Constructs 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);
}
/**
* Constructs 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 StrSubstitutor(final Map valueMap) {
this(StrLookup.mapLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
}
/**
* Constructs 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 StrSubstitutor(final Map valueMap, final String prefix, final String suffix) {
this(StrLookup.mapLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE);
}
/**
* Constructs 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 StrSubstitutor(final Map valueMap, final String prefix, final String suffix,
final char escape) {
this(StrLookup.mapLookup(valueMap), prefix, suffix, escape);
}
/**
* Constructs 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 StrSubstitutor(final Map valueMap, final String prefix, final String suffix,
final char escape, final String valueDelimiter) {
this(StrLookup.mapLookup(valueMap), prefix, suffix, escape, valueDelimiter);
}
/**
* Constructs a new instance and initializes it.
*
* @param variableResolver the variable resolver, may be null
*/
public StrSubstitutor(final StrLookup variableResolver) {
this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
}
/**
* Constructs 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(final StrLookup 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);
}
/**
* Constructs 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 StrSubstitutor(final StrLookup 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);
}
/**
* Constructs 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(
final StrLookup variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher,
final char escape) {
this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER);
}
/**
* Constructs 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 StrSubstitutor(
final StrLookup variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher,
final char escape, final StrMatcher 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 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());
}
/**
* Returns the escape character.
*
* @return The character used for escaping variable references
*/
public char getEscapeChar() {
return this.escapeChar;
}
/**
* Gets the variable default value delimiter matcher currently in use.
*
* The variable default value delimiter is the character or characters that delimit 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 StrMatcher getValueDelimiterMatcher() {
return valueDelimiterMatcher;
}
/**
* 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 StrMatcher getVariablePrefixMatcher() {
return prefixMatcher;
}
/**
* Gets the VariableResolver that is used to lookup variables.
*
* @return The VariableResolver
*/
public StrLookup getVariableResolver() {
return this.variableResolver;
}
/**
* 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 StrMatcher 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<String, String> valuesMap = new 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
*
* @since 1.2
*/
public boolean isDisableSubstitutionInValues() {
return disableSubstitutionInValues;
}
/**
* 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 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.
*
*
* @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 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 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 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 {@code 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 StrBuilder buf = new StrBuilder().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 StrBuilder source) {
if (source == null) {
return null;
}
final 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.
*
*
* @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 StrBuilder source, final int offset, final int length) {
if (source == null) {
return null;
}
final 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 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 StrBuilder buf = new StrBuilder(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 StrBuilder buf = new StrBuilder(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 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.
*
*
* @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 StrBuilder buf = new StrBuilder(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 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.
*
*
* @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 StrBuilder 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 StrBuilder buf = new StrBuilder(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 StrBuilder buf = new StrBuilder(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 #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 null if the variable is unknown
*/
protected String resolveVariable(final String variableName,
final StrBuilder buf,
final int startPos,
final int endPos) {
final StrLookup resolver = getVariableResolver();
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
*
* @since 1.2
*/
public void setDisableSubstitutionInValues(final boolean disableSubstitutionInValues) {
this.disableSubstitutionInValues = disableSubstitutionInValues;
}
/**
* 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.
* {@code ${jre-${java.version}}}. The default value is false.
*
* @param enableSubstitutionInVariables the new value of the flag
*/
public void setEnableSubstitutionInVariables(
final boolean enableSubstitutionInVariables) {
this.enableSubstitutionInVariables = enableSubstitutionInVariables;
}
/**
* 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(final char escapeCharacter) {
this.escapeChar = escapeCharacter;
}
/**
* Sets a flag controlling whether escapes are preserved during
* substitution. If set to true, the escape character is retained
* during substitution (e.g. {@code $${this-is-escaped}} remains
* {@code $${this-is-escaped}}). If set to false, the escape
* character is removed during substitution (e.g.
* {@code $${this-is-escaped}} becomes
* {@code ${this-is-escaped}}). The default value is false
*
* @param preserveEscapes true if escapes are to be preserved
*/
public void setPreserveEscapes(final boolean preserveEscapes) {
this.preserveEscapes = preserveEscapes;
}
/**
* Sets the variable default value delimiter to use.
*
* The variable default value delimiter is the character or characters that delimit 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 StrSubstitutor setValueDelimiter(final char valueDelimiter) {
return setValueDelimiterMatcher(StrMatcher.charMatcher(valueDelimiter));
}
/**
* Sets the variable default value delimiter to use.
*
* The variable default value delimiter is the character or characters that delimit the
* variable name and the variable default value. This method allows a string
* variable default value delimiter to be easily set.
*
*
* If the {@code 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 StrSubstitutor setValueDelimiter(final String valueDelimiter) {
if (valueDelimiter == null || valueDelimiter.isEmpty()) {
setValueDelimiterMatcher(null);
return this;
}
return setValueDelimiterMatcher(StrMatcher.stringMatcher(valueDelimiter));
}
/**
* Sets the variable default value delimiter matcher to use.
*
* The variable default value delimiter is the character or characters that delimit 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 {@code 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 StrSubstitutor setValueDelimiterMatcher(final StrMatcher 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 StrSubstitutor setVariablePrefix(final char prefix) {
return setVariablePrefixMatcher(StrMatcher.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 StrSubstitutor setVariablePrefix(final String prefix) {
Validate.isTrue(prefix != null, "Variable prefix must not be null!");
return setVariablePrefixMatcher(StrMatcher.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 StrSubstitutor setVariablePrefixMatcher(final StrMatcher 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
*/
public void setVariableResolver(final StrLookup variableResolver) {
this.variableResolver = variableResolver;
}
/**
* 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 StrSubstitutor setVariableSuffix(final 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.
*
*
* @param suffix the suffix for variables, not null
* @return this, to enable chaining
* @throws IllegalArgumentException if the suffix is null
*/
public StrSubstitutor setVariableSuffix(final String suffix) {
Validate.isTrue(suffix != null, "Variable suffix must not be null!");
return setVariableSuffixMatcher(StrMatcher.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 StrSubstitutor setVariableSuffixMatcher(final StrMatcher 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 StrBuilder 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 StrBuilder buf, final int offset, final int length, List priorVariables) {
final StrMatcher pfxMatcher = getVariablePrefixMatcher();
final StrMatcher suffMatcher = getVariableSuffixMatcher();
final char escape = getEscapeChar();
final StrMatcher 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 StrBuilder bufName = new StrBuilder(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) {
valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i);
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;
}
}