1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.text;
18
19 import java.util.ArrayList;
20 import java.util.List;
21 import java.util.Map;
22 import java.util.Objects;
23 import java.util.Properties;
24 import java.util.function.Function;
25 import java.util.stream.Collectors;
26
27 import org.apache.commons.lang3.Validate;
28 import org.apache.commons.text.lookup.StringLookup;
29 import org.apache.commons.text.lookup.StringLookupFactory;
30 import org.apache.commons.text.matcher.StringMatcher;
31 import org.apache.commons.text.matcher.StringMatcherFactory;
32
33 /**
34 * Substitutes variables within a string by values.
35 * <p>
36 * This class takes a piece of text and substitutes all the variables within it. The default definition of a variable is
37 * {@code ${variableName}}. The prefix and suffix can be changed via constructors and set methods.
38 * </p>
39 * <p>
40 * Variable values are typically resolved from a map, but could also be resolved from system properties, or by supplying
41 * a custom variable resolver.
42 * </p>
43 * <h2>Using System Properties</h2>
44 * <p>
45 * The simplest example is to use this class to replace Java System properties. For example:
46 * </p>
47 *
48 * <pre>
49 * StringSubstitutor
50 * .replaceSystemProperties("You are running with java.version = ${java.version} and os.name = ${os.name}.");
51 * </pre>
52 *
53 * <h2>Using a Custom Map</h2>
54 * <p>
55 * Typical usage of this class follows the following pattern:
56 * </p>
57 * <ul>
58 * <li>Create and initialize a StringSubstitutor with the map that contains the values for the variables you want to
59 * make available.</li>
60 * <li>Optionally set attributes like variable prefix, variable suffix, default value delimiter, and so on.</li>
61 * <li>Call the {@code replace()} method with in the source text for interpolation.</li>
62 * <li>The returned text contains all variable references (as long as their values are known) as resolved.</li>
63 * </ul>
64 * <p>
65 * For example:
66 * </p>
67 *
68 * <pre>
69 * // Build map
70 * Map<String, String> valuesMap = new HashMap<>();
71 * valuesMap.put("animal", "quick brown fox");
72 * valuesMap.put("target", "lazy dog");
73 * String templateString = "The ${animal} jumped over the ${target}.";
74 *
75 * // Build StringSubstitutor
76 * StringSubstitutor sub = new StringSubstitutor(valuesMap);
77 *
78 * // Replace
79 * String resolvedString = sub.replace(templateString);
80 * </pre>
81 *
82 * <p>
83 * yielding:
84 * </p>
85 *
86 * <pre>
87 * "The quick brown fox jumped over the lazy dog."
88 * </pre>
89 *
90 * <h2>Providing Default Values</h2>
91 * <p>
92 * You can set a default value for unresolved variables. The default value for a variable can be appended to the
93 * variable name after the variable default value delimiter. The default value of the variable default value delimiter
94 * is ":-", as in bash and other *nix shells.
95 * </p>
96 * <p>
97 * You can set the variable value delimiter with {@link #setValueDelimiterMatcher(StringMatcher)},
98 * {@link #setValueDelimiter(char)} or {@link #setValueDelimiter(String)}.
99 * </p>
100 * <p>
101 * For example:
102 * </p>
103 *
104 * <pre>
105 * // Build map
106 * Map<String, String> valuesMap = new HashMap<>();
107 * valuesMap.put("animal", "quick brown fox");
108 * valuesMap.put("target", "lazy dog");
109 * String templateString = "The ${animal} jumped over the ${target} ${undefined.number:-1234567890} times.";
110 *
111 * // Build StringSubstitutor
112 * StringSubstitutor sub = new StringSubstitutor(valuesMap);
113 *
114 * // Replace
115 * String resolvedString = sub.replace(templateString);
116 * </pre>
117 *
118 * <p>
119 * yielding:
120 * </p>
121 *
122 * <pre>
123 * "The quick brown fox jumped over the lazy dog 1234567890 times."
124 * </pre>
125 *
126 * <p>
127 * {@code StringSubstitutor} supports throwing exceptions for unresolved variables, you enable this by setting calling
128 * {@link #setEnableUndefinedVariableException(boolean)} with {@code true}.
129 * </p>
130 *
131 * <h2>Reusing Instances</h2>
132 * <p>
133 * Static shortcut methods cover the most common use cases. If multiple replace operations are to be performed, creating
134 * and reusing an instance of this class will be more efficient.
135 * </p>
136 *
137 * <h2>Using Interpolation</h2>
138 * <p>
139 * The default interpolator lets you use string lookups like:
140 * </p>
141 *
142 * <pre>
143 * final StringSubstitutor interpolator = StringSubstitutor.createInterpolator();
144 * final String text = interpolator.replace(
145 * "Base64 Decoder: ${base64Decoder:SGVsbG9Xb3JsZCE=}\n"
146 * + "Base64 Encoder: ${base64Encoder:HelloWorld!}\n"
147 * + "Java Constant: ${const:java.awt.event.KeyEvent.VK_ESCAPE}\n"
148 * + "Date: ${date:yyyy-MM-dd}\n"
149 * + "Environment Variable: ${env:USERNAME}\n"
150 * + "File Content: ${file:UTF-8:src/test/resources/document.properties}\n"
151 * + "Java: ${java:version}\n"
152 * + "Localhost: ${localhost:canonical-name}\n"
153 * + "Properties File: ${properties:src/test/resources/document.properties::mykey}\n"
154 * + "Resource Bundle: ${resourceBundle:org.apache.commons.text.example.testResourceBundleLookup:mykey}\n"
155 * + "System Property: ${sys:user.dir}\n"
156 * + "URL Decoder: ${urlDecoder:Hello%20World%21}\n"
157 * + "URL Encoder: ${urlEncoder:Hello World!}\n"
158 * + "XML XPath: ${xml:src/test/resources/document.xml:/root/path/to/node}\n");
159 * </pre>
160 * <p>
161 * For documentation and a full list of available lookups, see {@link StringLookupFactory}.
162 * </p>
163 * <p><strong>NOTE:</strong> The list of lookups available by default in {@link #createInterpolator()} changed
164 * in version {@code 1.10.0}. See the {@link StringLookupFactory} documentation for details and an explanation
165 * on how to reproduce the previous functionality.
166 * </p>
167 *
168 * <h2>Using Recursive Variable Replacement</h2>
169 * <p>
170 * Variable replacement can work recursively by calling {@link #setEnableSubstitutionInVariables(boolean)} with
171 * {@code true}. If a variable value contains a variable then that variable will also be replaced. Cyclic replacements
172 * are detected and will throw an exception.
173 * </p>
174 * <p>
175 * You can get the replace result to contain a variable prefix. For example:
176 * </p>
177 *
178 * <pre>
179 * "The variable ${${name}} must be used."
180 * </pre>
181 *
182 * <p>
183 * If the value of the "name" variable is "x", then only the variable "name" is replaced resulting in:
184 * </p>
185 *
186 * <pre>
187 * "The variable ${x} must be used."
188 * </pre>
189 *
190 * <p>
191 * To achieve this effect there are two possibilities: Either set a different prefix and suffix for variables which do
192 * not conflict with the result text you want to produce. The other possibility is to use the escape character, by
193 * default '$'. If this character is placed before a variable reference, this reference is ignored and won't be
194 * replaced. For example:
195 * </p>
196 *
197 * <pre>
198 * "The variable $${${name}} must be used."
199 * </pre>
200 * <p>
201 * In some complex scenarios you might even want to perform substitution in the names of variables, for instance
202 * </p>
203 *
204 * <pre>
205 * ${jre-${java.specification.version}}
206 * </pre>
207 *
208 * <p>
209 * {@code StringSubstitutor} supports this recursive substitution in variable names, but it has to be enabled explicitly
210 * by calling {@link #setEnableSubstitutionInVariables(boolean)} with {@code true}.
211 * </p>
212 *
213 * <h2>Thread Safety</h2>
214 * <p>
215 * This class is <b>not</b> thread safe.
216 * </p>
217 *
218 * @since 1.3
219 */
220 public class StringSubstitutor {
221
222 /**
223 * The low-level result of a substitution.
224 *
225 * @since 1.9
226 */
227 private static final class Result {
228
229 /** Whether the buffer is altered. */
230 public final boolean altered;
231
232 /** The length of change. */
233 public final int lengthChange;
234
235 private Result(final boolean altered, final int lengthChange) {
236 this.altered = altered;
237 this.lengthChange = lengthChange;
238 }
239
240 @Override
241 public String toString() {
242 return "Result [altered=" + altered + ", lengthChange=" + lengthChange + "]";
243 }
244 }
245
246 /**
247 * Constant for the default escape character.
248 */
249 public static final char DEFAULT_ESCAPE = '$';
250
251 /**
252 * The default variable default separator.
253 *
254 * @since 1.5.
255 */
256 public static final String DEFAULT_VAR_DEFAULT = ":-";
257
258 /**
259 * The default variable end separator.
260 *
261 * @since 1.5.
262 */
263 public static final String DEFAULT_VAR_END = "}";
264
265 /**
266 * The default variable start separator.
267 *
268 * @since 1.5.
269 */
270 public static final String DEFAULT_VAR_START = "${";
271
272 /**
273 * Constant for the default variable prefix.
274 */
275 public static final StringMatcher DEFAULT_PREFIX = StringMatcherFactory.INSTANCE.stringMatcher(DEFAULT_VAR_START);
276
277 /**
278 * Constant for the default variable suffix.
279 */
280 public static final StringMatcher DEFAULT_SUFFIX = StringMatcherFactory.INSTANCE.stringMatcher(DEFAULT_VAR_END);
281
282 /**
283 * Constant for the default value delimiter of a variable.
284 */
285 public static final StringMatcher DEFAULT_VALUE_DELIMITER = StringMatcherFactory.INSTANCE
286 .stringMatcher(DEFAULT_VAR_DEFAULT);
287
288 /**
289 * Creates a new instance using the interpolator string lookup
290 * {@link StringLookupFactory#interpolatorStringLookup()}.
291 * <p>
292 * This StringSubstitutor lets you perform substitutions like:
293 * </p>
294 *
295 * <pre>
296 * StringSubstitutor.createInterpolator().replace(
297 * "OS name: ${sys:os.name}, user: ${env:USER}");
298 * </pre>
299 *
300 * <p>The table below lists the lookups available by default in the returned instance. These
301 * may be modified through the use of the
302 * {@value org.apache.commons.text.lookup.StringLookupFactory#DEFAULT_STRING_LOOKUPS_PROPERTY}
303 * system property, as described in the {@link StringLookupFactory} documentation.</p>
304 *
305 * <p><strong>NOTE:</strong> The list of lookups available by default changed in version {@code 1.10.0}.
306 * Configuration via system property (as mentioned above) may be necessary to reproduce previous functionality.
307 * </p>
308 *
309 * <table>
310 * <caption>Default Lookups</caption>
311 * <tr>
312 * <th>Key</th>
313 * <th>Lookup</th>
314 * </tr>
315 * <tr>
316 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_BASE64_DECODER}</td>
317 * <td>{@link StringLookupFactory#base64DecoderStringLookup()}</td>
318 * </tr>
319 * <tr>
320 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_BASE64_ENCODER}</td>
321 * <td>{@link StringLookupFactory#base64EncoderStringLookup()}</td>
322 * </tr>
323 * <tr>
324 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_CONST}</td>
325 * <td>{@link StringLookupFactory#constantStringLookup()}</td>
326 * </tr>
327 * <tr>
328 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_DATE}</td>
329 * <td>{@link StringLookupFactory#dateStringLookup()}</td>
330 * </tr>
331 * <tr>
332 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_ENV}</td>
333 * <td>{@link StringLookupFactory#environmentVariableStringLookup()}</td>
334 * </tr>
335 * <tr>
336 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_FILE}</td>
337 * <td>{@link StringLookupFactory#fileStringLookup()}</td>
338 * </tr>
339 * <tr>
340 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_JAVA}</td>
341 * <td>{@link StringLookupFactory#javaPlatformStringLookup()}</td>
342 * </tr>
343 * <tr>
344 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_LOCALHOST}</td>
345 * <td>{@link StringLookupFactory#localHostStringLookup()}</td>
346 * </tr>
347 * <tr>
348 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_PROPERTIES}</td>
349 * <td>{@link StringLookupFactory#propertiesStringLookup()}</td>
350 * </tr>
351 * <tr>
352 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_RESOURCE_BUNDLE}</td>
353 * <td>{@link StringLookupFactory#resourceBundleStringLookup()}</td>
354 * </tr>
355 * <tr>
356 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_SYS}</td>
357 * <td>{@link StringLookupFactory#systemPropertyStringLookup()}</td>
358 * </tr>
359 * <tr>
360 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_URL_DECODER}</td>
361 * <td>{@link StringLookupFactory#urlDecoderStringLookup()}</td>
362 * </tr>
363 * <tr>
364 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_URL_ENCODER}</td>
365 * <td>{@link StringLookupFactory#urlEncoderStringLookup()}</td>
366 * </tr>
367 * <tr>
368 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_XML}</td>
369 * <td>{@link StringLookupFactory#xmlStringLookup()}</td>
370 * </tr>
371 * <tr>
372 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_XML_DECODER}</td>
373 * <td>{@link StringLookupFactory#xmlDecoderStringLookup()}</td>
374 * </tr>
375 * <tr>
376 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_XML_ENCODER}</td>
377 * <td>{@link StringLookupFactory#xmlEncoderStringLookup()}</td>
378 * </tr>
379 * </table>
380 *
381 * @return a new instance using the interpolator string lookup.
382 * @see StringLookupFactory#interpolatorStringLookup()
383 * @since 1.8
384 */
385 public static StringSubstitutor createInterpolator() {
386 return new StringSubstitutor(StringLookupFactory.INSTANCE.interpolatorStringLookup());
387 }
388
389 /**
390 * Replaces all the occurrences of variables in the given source object with their matching values from the map.
391 *
392 * @param <V> the type of the values in the map
393 * @param source the source text containing the variables to substitute, null returns null
394 * @param valueMap the map with the values, may be null
395 * @return The result of the replace operation
396 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
397 */
398 public static <V> String replace(final Object source, final Map<String, V> valueMap) {
399 return new StringSubstitutor(valueMap).replace(source);
400 }
401
402 /**
403 * Replaces all the occurrences of variables in the given source object with their matching values from the map.
404 * This method allows to specify a custom variable prefix and suffix
405 *
406 * @param <V> the type of the values in the map
407 * @param source the source text containing the variables to substitute, null returns null
408 * @param valueMap the map with the values, may be null
409 * @param prefix the prefix of variables, not null
410 * @param suffix the suffix of variables, not null
411 * @return The result of the replace operation
412 * @throws IllegalArgumentException if the prefix or suffix is null
413 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
414 */
415 public static <V> String replace(final Object source, final Map<String, V> valueMap, final String prefix,
416 final String suffix) {
417 return new StringSubstitutor(valueMap, prefix, suffix).replace(source);
418 }
419
420 /**
421 * Replaces all the occurrences of variables in the given source object with their matching values from the
422 * properties.
423 *
424 * @param source the source text containing the variables to substitute, null returns null
425 * @param valueProperties the properties with values, may be null
426 * @return The result of the replace operation
427 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
428 */
429 public static String replace(final Object source, final Properties valueProperties) {
430 if (valueProperties == null) {
431 return source.toString();
432 }
433 return StringSubstitutor.replace(source,
434 valueProperties.stringPropertyNames().stream().collect(Collectors.toMap(Function.identity(), valueProperties::getProperty)));
435 }
436
437 /**
438 * Replaces all the occurrences of variables in the given source object with their matching values from the system
439 * properties.
440 *
441 * @param source the source text containing the variables to substitute, null returns null
442 * @return The result of the replace operation
443 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
444 */
445 public static String replaceSystemProperties(final Object source) {
446 return new StringSubstitutor(StringLookupFactory.INSTANCE.systemPropertyStringLookup()).replace(source);
447 }
448
449 /**
450 * The flag whether substitution in variable values is disabled.
451 */
452 private boolean disableSubstitutionInValues;
453
454 /**
455 * The flag whether substitution in variable names is enabled.
456 */
457 private boolean enableSubstitutionInVariables;
458
459 /**
460 * The flag whether exception should be thrown on undefined variable.
461 */
462 private boolean enableUndefinedVariableException;
463
464 /**
465 * Stores the escape character.
466 */
467 private char escapeChar;
468
469 /**
470 * Stores the variable prefix.
471 */
472 private StringMatcher prefixMatcher;
473
474 /**
475 * Whether escapes should be preserved. Default is false;
476 */
477 private boolean preserveEscapes;
478
479 /**
480 * Stores the variable suffix.
481 */
482 private StringMatcher suffixMatcher;
483
484 /**
485 * Stores the default variable value delimiter.
486 */
487 private StringMatcher valueDelimiterMatcher;
488
489 /**
490 * Variable resolution is delegated to an implementor of {@link StringLookup}.
491 */
492 private StringLookup variableResolver;
493
494 /**
495 * Constructs a new instance with defaults for variable prefix and suffix and the escaping character.
496 */
497 public StringSubstitutor() {
498 this((StringLookup) null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
499 }
500
501 /**
502 * Constructs a new initialized instance. Uses defaults for variable prefix and suffix and the escaping
503 * character.
504 *
505 * @param <V> the type of the values in the map
506 * @param valueMap the map with the variables' values, may be null
507 */
508 public <V> StringSubstitutor(final Map<String, V> valueMap) {
509 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
510 }
511
512 /**
513 * Constructs a new initialized instance. Uses a default escaping character.
514 *
515 * @param <V> the type of the values in the map
516 * @param valueMap the map with the variables' values, may be null
517 * @param prefix the prefix for variables, not null
518 * @param suffix the suffix for variables, not null
519 * @throws IllegalArgumentException if the prefix or suffix is null
520 */
521 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix) {
522 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE);
523 }
524
525 /**
526 * Constructs a new initialized instance.
527 *
528 * @param <V> the type of the values in the map
529 * @param valueMap the map with the variables' values, may be null
530 * @param prefix the prefix for variables, not null
531 * @param suffix the suffix for variables, not null
532 * @param escape the escape character
533 * @throws IllegalArgumentException if the prefix or suffix is null
534 */
535 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
536 final char escape) {
537 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, escape);
538 }
539
540 /**
541 * Constructs a new initialized instance.
542 *
543 * @param <V> the type of the values in the map
544 * @param valueMap the map with the variables' values, may be null
545 * @param prefix the prefix for variables, not null
546 * @param suffix the suffix for variables, not null
547 * @param escape the escape character
548 * @param valueDelimiter the variable default value delimiter, may be null
549 * @throws IllegalArgumentException if the prefix or suffix is null
550 */
551 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
552 final char escape, final String valueDelimiter) {
553 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, escape, valueDelimiter);
554 }
555
556 /**
557 * Constructs a new initialized instance.
558 *
559 * @param variableResolver the variable resolver, may be null
560 */
561 public StringSubstitutor(final StringLookup variableResolver) {
562 this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
563 }
564
565 /**
566 * Constructs a new initialized instance.
567 *
568 * @param variableResolver the variable resolver, may be null
569 * @param prefix the prefix for variables, not null
570 * @param suffix the suffix for variables, not null
571 * @param escape the escape character
572 * @throws IllegalArgumentException if the prefix or suffix is null
573 */
574 public StringSubstitutor(final StringLookup variableResolver, final String prefix, final String suffix,
575 final char escape) {
576 this.setVariableResolver(variableResolver);
577 this.setVariablePrefix(prefix);
578 this.setVariableSuffix(suffix);
579 this.setEscapeChar(escape);
580 this.setValueDelimiterMatcher(DEFAULT_VALUE_DELIMITER);
581 }
582
583 /**
584 * Constructs a new initialized instance.
585 *
586 * @param variableResolver the variable resolver, may be null
587 * @param prefix the prefix for variables, not null
588 * @param suffix the suffix for variables, not null
589 * @param escape the escape character
590 * @param valueDelimiter the variable default value delimiter string, may be null
591 * @throws IllegalArgumentException if the prefix or suffix is null
592 */
593 public StringSubstitutor(final StringLookup variableResolver, final String prefix, final String suffix,
594 final char escape, final String valueDelimiter) {
595 this.setVariableResolver(variableResolver);
596 this.setVariablePrefix(prefix);
597 this.setVariableSuffix(suffix);
598 this.setEscapeChar(escape);
599 this.setValueDelimiter(valueDelimiter);
600 }
601
602 /**
603 * Constructs a new initialized instance.
604 *
605 * @param variableResolver the variable resolver, may be null
606 * @param prefixMatcher the prefix for variables, not null
607 * @param suffixMatcher the suffix for variables, not null
608 * @param escape the escape character
609 * @throws IllegalArgumentException if the prefix or suffix is null
610 */
611 public StringSubstitutor(final StringLookup variableResolver, final StringMatcher prefixMatcher,
612 final StringMatcher suffixMatcher, final char escape) {
613 this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER);
614 }
615
616 /**
617 * Constructs a new initialized instance.
618 *
619 * @param variableResolver the variable resolver, may be null
620 * @param prefixMatcher the prefix for variables, not null
621 * @param suffixMatcher the suffix for variables, not null
622 * @param escape the escape character
623 * @param valueDelimiterMatcher the variable default value delimiter matcher, may be null
624 * @throws IllegalArgumentException if the prefix or suffix is null
625 */
626 public StringSubstitutor(final StringLookup variableResolver, final StringMatcher prefixMatcher,
627 final StringMatcher suffixMatcher, final char escape, final StringMatcher valueDelimiterMatcher) {
628 this.setVariableResolver(variableResolver);
629 this.setVariablePrefixMatcher(prefixMatcher);
630 this.setVariableSuffixMatcher(suffixMatcher);
631 this.setEscapeChar(escape);
632 this.setValueDelimiterMatcher(valueDelimiterMatcher);
633 }
634
635 /**
636 * Creates a new instance based on the given StringSubstitutor.
637 *
638 * @param other The StringSubstitutor used as the source.
639 * @since 1.9
640 */
641 public StringSubstitutor(final StringSubstitutor other) {
642 disableSubstitutionInValues = other.isDisableSubstitutionInValues();
643 enableSubstitutionInVariables = other.isEnableSubstitutionInVariables();
644 enableUndefinedVariableException = other.isEnableUndefinedVariableException();
645 escapeChar = other.getEscapeChar();
646 prefixMatcher = other.getVariablePrefixMatcher();
647 preserveEscapes = other.isPreserveEscapes();
648 suffixMatcher = other.getVariableSuffixMatcher();
649 valueDelimiterMatcher = other.getValueDelimiterMatcher();
650 variableResolver = other.getStringLookup();
651 }
652
653 /**
654 * Checks if the specified variable is already in the stack (list) of variables.
655 *
656 * @param varName the variable name to check
657 * @param priorVariables the list of prior variables
658 */
659 private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) {
660 if (!priorVariables.contains(varName)) {
661 return;
662 }
663 final TextStringBuilder buf = new TextStringBuilder(256);
664 buf.append("Infinite loop in property interpolation of ");
665 buf.append(priorVariables.remove(0));
666 buf.append(": ");
667 buf.appendWithSeparators(priorVariables, "->");
668 throw new IllegalStateException(buf.toString());
669 }
670
671 // Escape
672 /**
673 * Returns the escape character.
674 *
675 * @return The character used for escaping variable references
676 */
677 public char getEscapeChar() {
678 return this.escapeChar;
679 }
680
681 /**
682 * Gets the StringLookup that is used to lookup variables.
683 *
684 * @return The StringLookup
685 */
686 public StringLookup getStringLookup() {
687 return this.variableResolver;
688 }
689
690 /**
691 * Gets the variable default value delimiter matcher currently in use.
692 * <p>
693 * The variable default value delimiter is the character or characters that delimit the variable name and the
694 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default
695 * value delimiter matches.
696 * </p>
697 * <p>
698 * If it returns null, then the variable default value resolution is disabled.
699 *
700 * @return The variable default value delimiter matcher in use, may be null
701 */
702 public StringMatcher getValueDelimiterMatcher() {
703 return valueDelimiterMatcher;
704 }
705
706 /**
707 * Gets the variable prefix matcher currently in use.
708 * <p>
709 * The variable prefix is the character or characters that identify the start of a variable. This prefix is
710 * expressed in terms of a matcher allowing advanced prefix matches.
711 * </p>
712 *
713 * @return The prefix matcher in use
714 */
715 public StringMatcher getVariablePrefixMatcher() {
716 return prefixMatcher;
717 }
718
719 /**
720 * Gets the variable suffix matcher currently in use.
721 * <p>
722 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed
723 * in terms of a matcher allowing advanced suffix matches.
724 * </p>
725 *
726 * @return The suffix matcher in use
727 */
728 public StringMatcher getVariableSuffixMatcher() {
729 return suffixMatcher;
730 }
731
732 /**
733 * Returns a flag whether substitution is disabled in variable values.If set to <b>true</b>, the values of variables
734 * can contain other variables will not be processed and substituted original variable is evaluated, e.g.
735 *
736 * <pre>
737 * Map<String, String> valuesMap = new HashMap<>();
738 * valuesMap.put("name", "Douglas ${surname}");
739 * valuesMap.put("surname", "Crockford");
740 * String templateString = "Hi ${name}";
741 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
742 * String resolvedString = sub.replace(templateString);
743 * </pre>
744 *
745 * yielding:
746 *
747 * <pre>
748 * Hi Douglas ${surname}
749 * </pre>
750 *
751 * @return The substitution in variable values flag
752 */
753 public boolean isDisableSubstitutionInValues() {
754 return disableSubstitutionInValues;
755 }
756
757 /**
758 * Returns a flag whether substitution is done in variable names.
759 *
760 * @return The substitution in variable names flag
761 */
762 public boolean isEnableSubstitutionInVariables() {
763 return enableSubstitutionInVariables;
764 }
765
766 /**
767 * Returns a flag whether exception can be thrown upon undefined variable.
768 *
769 * @return The fail on undefined variable flag
770 */
771 public boolean isEnableUndefinedVariableException() {
772 return enableUndefinedVariableException;
773 }
774
775 /**
776 * Returns the flag controlling whether escapes are preserved during substitution.
777 *
778 * @return The preserve escape flag
779 */
780 public boolean isPreserveEscapes() {
781 return preserveEscapes;
782 }
783
784 /**
785 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
786 * array as a template. The array is not altered by this method.
787 *
788 * @param source the character array to replace in, not altered, null returns null
789 * @return The result of the replace operation
790 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
791 */
792 public String replace(final char[] source) {
793 if (source == null) {
794 return null;
795 }
796 final TextStringBuilder buf = new TextStringBuilder(source.length).append(source);
797 substitute(buf, 0, source.length);
798 return buf.toString();
799 }
800
801 /**
802 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
803 * array as a template. The array is not altered by this method.
804 * <p>
805 * Only the specified portion of the array will be processed. The rest of the array is not processed, and is not
806 * returned.
807 * </p>
808 *
809 * @param source the character array to replace in, not altered, null returns null
810 * @param offset the start offset within the array, must be valid
811 * @param length the length within the array to be processed, must be valid
812 * @return The result of the replace operation
813 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
814 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the
815 * range {@code 0 <= offset <= chars.length}
816 * @throws StringIndexOutOfBoundsException if {@code length < 0}
817 * @throws StringIndexOutOfBoundsException if {@code offset + length > chars.length}
818 */
819 public String replace(final char[] source, final int offset, final int length) {
820 if (source == null) {
821 return null;
822 }
823 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
824 substitute(buf, 0, length);
825 return buf.toString();
826 }
827
828 /**
829 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as
830 * a template. The source is not altered by this method.
831 *
832 * @param source the buffer to use as a template, not changed, null returns null
833 * @return The result of the replace operation
834 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
835 */
836 public String replace(final CharSequence source) {
837 if (source == null) {
838 return null;
839 }
840 return replace(source, 0, source.length());
841 }
842
843 /**
844 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as
845 * a template. The source is not altered by this method.
846 * <p>
847 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not
848 * returned.
849 * </p>
850 *
851 * @param source the buffer to use as a template, not changed, null returns null
852 * @param offset the start offset within the array, must be valid
853 * @param length the length within the array to be processed, must be valid
854 * @return The result of the replace operation
855 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
856 */
857 public String replace(final CharSequence source, final int offset, final int length) {
858 if (source == null) {
859 return null;
860 }
861 final TextStringBuilder buf = new TextStringBuilder(length).append(source.toString(), offset, length);
862 substitute(buf, 0, length);
863 return buf.toString();
864 }
865
866 /**
867 * Replaces all the occurrences of variables in the given source object with their matching values from the
868 * resolver. The input source object is converted to a string using {@code toString} and is not altered.
869 *
870 * @param source the source to replace in, null returns null
871 * @return The result of the replace operation
872 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
873 */
874 public String replace(final Object source) {
875 if (source == null) {
876 return null;
877 }
878 final TextStringBuilder buf = new TextStringBuilder().append(source);
879 substitute(buf, 0, buf.length());
880 return buf.toString();
881 }
882
883 /**
884 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
885 * string as a template.
886 *
887 * @param source the string to replace in, null returns null
888 * @return The result of the replace operation
889 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
890 */
891 public String replace(final String source) {
892 if (source == null) {
893 return null;
894 }
895 final TextStringBuilder buf = new TextStringBuilder(source);
896 if (!substitute(buf, 0, source.length())) {
897 return source;
898 }
899 return buf.toString();
900 }
901
902 /**
903 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
904 * string as a template.
905 * <p>
906 * Only the specified portion of the string will be processed. The rest of the string is not processed, and is not
907 * returned.
908 * </p>
909 *
910 * @param source the string to replace in, null returns null
911 * @param offset the start offset within the source, must be valid
912 * @param length the length within the source to be processed, must be valid
913 * @return The result of the replace operation
914 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
915 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the
916 * range {@code 0 <= offset <= source.length()}
917 * @throws StringIndexOutOfBoundsException if {@code length < 0}
918 * @throws StringIndexOutOfBoundsException if {@code offset + length > source.length()}
919 */
920 public String replace(final String source, final int offset, final int length) {
921 if (source == null) {
922 return null;
923 }
924 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
925 if (!substitute(buf, 0, length)) {
926 return source.substring(offset, offset + length);
927 }
928 return buf.toString();
929 }
930
931 /**
932 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
933 * buffer as a template. The buffer is not altered by this method.
934 *
935 * @param source the buffer to use as a template, not changed, null returns null
936 * @return The result of the replace operation
937 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
938 */
939 public String replace(final StringBuffer source) {
940 if (source == null) {
941 return null;
942 }
943 final TextStringBuilder buf = new TextStringBuilder(source.length()).append(source);
944 substitute(buf, 0, buf.length());
945 return buf.toString();
946 }
947
948 /**
949 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
950 * buffer as a template. The buffer is not altered by this method.
951 * <p>
952 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not
953 * returned.
954 * </p>
955 *
956 * @param source the buffer to use as a template, not changed, null returns null
957 * @param offset the start offset within the source, must be valid
958 * @param length the length within the source to be processed, must be valid
959 * @return The result of the replace operation
960 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
961 */
962 public String replace(final StringBuffer source, final int offset, final int length) {
963 if (source == null) {
964 return null;
965 }
966 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
967 substitute(buf, 0, length);
968 return buf.toString();
969 }
970
971 /**
972 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
973 * builder as a template. The builder is not altered by this method.
974 *
975 * @param source the builder to use as a template, not changed, null returns null
976 * @return The result of the replace operation
977 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
978 */
979 public String replace(final TextStringBuilder source) {
980 if (source == null) {
981 return null;
982 }
983 final TextStringBuilder builder = new TextStringBuilder(source.length()).append(source);
984 substitute(builder, 0, builder.length());
985 return builder.toString();
986 }
987
988 /**
989 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
990 * builder as a template. The builder is not altered by this method.
991 * <p>
992 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, and is not
993 * returned.
994 * </p>
995 *
996 * @param source the builder to use as a template, not changed, null returns null
997 * @param offset the start offset within the source, must be valid
998 * @param length the length within the source to be processed, must be valid
999 * @return The result of the replace operation
1000 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1001 */
1002 public String replace(final TextStringBuilder source, final int offset, final int length) {
1003 if (source == null) {
1004 return null;
1005 }
1006 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1007 substitute(buf, 0, length);
1008 return buf.toString();
1009 }
1010
1011 /**
1012 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1013 * resolver. The buffer is updated with the result.
1014 *
1015 * @param source the buffer to replace in, updated, null returns zero
1016 * @return true if altered
1017 */
1018 public boolean replaceIn(final StringBuffer source) {
1019 if (source == null) {
1020 return false;
1021 }
1022 return replaceIn(source, 0, source.length());
1023 }
1024
1025 /**
1026 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1027 * resolver. The buffer is updated with the result.
1028 * <p>
1029 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is
1030 * not deleted.
1031 * </p>
1032 *
1033 * @param source the buffer to replace in, updated, null returns zero
1034 * @param offset the start offset within the source, must be valid
1035 * @param length the length within the source to be processed, must be valid
1036 * @return true if altered
1037 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1038 */
1039 public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
1040 if (source == null) {
1041 return false;
1042 }
1043 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1044 if (!substitute(buf, 0, length)) {
1045 return false;
1046 }
1047 source.replace(offset, offset + length, buf.toString());
1048 return true;
1049 }
1050
1051 /**
1052 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1053 * resolver. The buffer is updated with the result.
1054 *
1055 * @param source the buffer to replace in, updated, null returns zero
1056 * @return true if altered
1057 */
1058 public boolean replaceIn(final StringBuilder source) {
1059 if (source == null) {
1060 return false;
1061 }
1062 return replaceIn(source, 0, source.length());
1063 }
1064
1065 /**
1066 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1067 * resolver. The builder is updated with the result.
1068 * <p>
1069 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is
1070 * not deleted.
1071 * </p>
1072 *
1073 * @param source the buffer to replace in, updated, null returns zero
1074 * @param offset the start offset within the source, must be valid
1075 * @param length the length within the source to be processed, must be valid
1076 * @return true if altered
1077 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1078 */
1079 public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
1080 if (source == null) {
1081 return false;
1082 }
1083 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1084 if (!substitute(buf, 0, length)) {
1085 return false;
1086 }
1087 source.replace(offset, offset + length, buf.toString());
1088 return true;
1089 }
1090
1091 /**
1092 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1093 * resolver.
1094 *
1095 * @param source the builder to replace in, updated, null returns zero
1096 * @return true if altered
1097 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1098 */
1099 public boolean replaceIn(final TextStringBuilder source) {
1100 if (source == null) {
1101 return false;
1102 }
1103 return substitute(source, 0, source.length());
1104 }
1105
1106 /**
1107 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1108 * resolver.
1109 * <p>
1110 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, but it is
1111 * not deleted.
1112 * </p>
1113 *
1114 * @param source the builder to replace in, null returns zero
1115 * @param offset the start offset within the source, must be valid
1116 * @param length the length within the source to be processed, must be valid
1117 * @return true if altered
1118 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1119 */
1120 public boolean replaceIn(final TextStringBuilder source, final int offset, final int length) {
1121 if (source == null) {
1122 return false;
1123 }
1124 return substitute(source, offset, length);
1125 }
1126
1127 /**
1128 * Internal method that resolves the value of a variable.
1129 * <p>
1130 * Most users of this class do not need to call this method. This method is called automatically by the substitution
1131 * process.
1132 * </p>
1133 * <p>
1134 * Writers of subclasses can override this method if they need to alter how each substitution occurs. The method is
1135 * passed the variable's name and must return the corresponding value. This implementation uses the
1136 * {@link #getStringLookup()} with the variable's name as the key.
1137 * </p>
1138 *
1139 * @param variableName the name of the variable, not null
1140 * @param buf the buffer where the substitution is occurring, not null
1141 * @param startPos the start position of the variable including the prefix, valid
1142 * @param endPos the end position of the variable including the suffix, valid
1143 * @return The variable's value or <b>null</b> if the variable is unknown
1144 */
1145 protected String resolveVariable(final String variableName, final TextStringBuilder buf, final int startPos,
1146 final int endPos) {
1147 final StringLookup resolver = getStringLookup();
1148 if (resolver == null) {
1149 return null;
1150 }
1151 return resolver.lookup(variableName);
1152 }
1153
1154 /**
1155 * Sets a flag whether substitution is done in variable values (recursive).
1156 *
1157 * @param disableSubstitutionInValues true if substitution in variable value are disabled
1158 * @return this, to enable chaining
1159 */
1160 public StringSubstitutor setDisableSubstitutionInValues(final boolean disableSubstitutionInValues) {
1161 this.disableSubstitutionInValues = disableSubstitutionInValues;
1162 return this;
1163 }
1164
1165 /**
1166 * Sets a flag whether substitution is done in variable names. If set to <b>true</b>, the names of variables can
1167 * contain other variables which are processed first before the original variable is evaluated, e.g.
1168 * {@code ${jre-${java.version}}}. The default value is <b>false</b>.
1169 *
1170 * @param enableSubstitutionInVariables the new value of the flag
1171 * @return this, to enable chaining
1172 */
1173 public StringSubstitutor setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) {
1174 this.enableSubstitutionInVariables = enableSubstitutionInVariables;
1175 return this;
1176 }
1177
1178 /**
1179 * Sets a flag whether exception should be thrown if any variable is undefined.
1180 *
1181 * @param failOnUndefinedVariable true if exception should be thrown on undefined variable
1182 * @return this, to enable chaining
1183 */
1184 public StringSubstitutor setEnableUndefinedVariableException(final boolean failOnUndefinedVariable) {
1185 this.enableUndefinedVariableException = failOnUndefinedVariable;
1186 return this;
1187 }
1188
1189 /**
1190 * Sets the escape character. If this character is placed before a variable reference in the source text, this
1191 * variable will be ignored.
1192 *
1193 * @param escapeCharacter the escape character (0 for disabling escaping)
1194 * @return this, to enable chaining
1195 */
1196 public StringSubstitutor setEscapeChar(final char escapeCharacter) {
1197 this.escapeChar = escapeCharacter;
1198 return this;
1199 }
1200
1201 /**
1202 * Sets a flag controlling whether escapes are preserved during substitution. If set to <b>true</b>, the escape
1203 * character is retained during substitution (e.g. {@code $${this-is-escaped}} remains {@code $${this-is-escaped}}).
1204 * If set to <b>false</b>, the escape character is removed during substitution (e.g. {@code $${this-is-escaped}}
1205 * becomes {@code ${this-is-escaped}}). The default value is <b>false</b>
1206 *
1207 * @param preserveEscapes true if escapes are to be preserved
1208 * @return this, to enable chaining
1209 */
1210 public StringSubstitutor setPreserveEscapes(final boolean preserveEscapes) {
1211 this.preserveEscapes = preserveEscapes;
1212 return this;
1213 }
1214
1215 /**
1216 * Sets the variable default value delimiter to use.
1217 * <p>
1218 * The variable default value delimiter is the character or characters that delimit the variable name and the
1219 * variable default value. This method allows a single character variable default value delimiter to be easily set.
1220 * </p>
1221 *
1222 * @param valueDelimiter the variable default value delimiter character to use
1223 * @return this, to enable chaining
1224 */
1225 public StringSubstitutor setValueDelimiter(final char valueDelimiter) {
1226 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.charMatcher(valueDelimiter));
1227 }
1228
1229 /**
1230 * Sets the variable default value delimiter to use.
1231 * <p>
1232 * The variable default value delimiter is the character or characters that delimit the variable name and the
1233 * variable default value. This method allows a string variable default value delimiter to be easily set.
1234 * </p>
1235 * <p>
1236 * If the {@code valueDelimiter} is null or empty string, then the variable default value resolution becomes
1237 * disabled.
1238 * </p>
1239 *
1240 * @param valueDelimiter the variable default value delimiter string to use, may be null or empty
1241 * @return this, to enable chaining
1242 */
1243 public StringSubstitutor setValueDelimiter(final String valueDelimiter) {
1244 if (valueDelimiter == null || valueDelimiter.isEmpty()) {
1245 setValueDelimiterMatcher(null);
1246 return this;
1247 }
1248 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.stringMatcher(valueDelimiter));
1249 }
1250
1251 /**
1252 * Sets the variable default value delimiter matcher to use.
1253 * <p>
1254 * The variable default value delimiter is the character or characters that delimit the variable name and the
1255 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default
1256 * value delimiter matches.
1257 * </p>
1258 * <p>
1259 * If the {@code valueDelimiterMatcher} is null, then the variable default value resolution becomes disabled.
1260 * </p>
1261 *
1262 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null
1263 * @return this, to enable chaining
1264 */
1265 public StringSubstitutor setValueDelimiterMatcher(final StringMatcher valueDelimiterMatcher) {
1266 this.valueDelimiterMatcher = valueDelimiterMatcher;
1267 return this;
1268 }
1269
1270 /**
1271 * Sets the variable prefix to use.
1272 * <p>
1273 * The variable prefix is the character or characters that identify the start of a variable. This method allows a
1274 * single character prefix to be easily set.
1275 * </p>
1276 *
1277 * @param prefix the prefix character to use
1278 * @return this, to enable chaining
1279 */
1280 public StringSubstitutor setVariablePrefix(final char prefix) {
1281 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.charMatcher(prefix));
1282 }
1283
1284 /**
1285 * Sets the variable prefix to use.
1286 * <p>
1287 * The variable prefix is the character or characters that identify the start of a variable. This method allows a
1288 * string prefix to be easily set.
1289 * </p>
1290 *
1291 * @param prefix the prefix for variables, not null
1292 * @return this, to enable chaining
1293 * @throws IllegalArgumentException if the prefix is null
1294 */
1295 public StringSubstitutor setVariablePrefix(final String prefix) {
1296 Validate.isTrue(prefix != null, "Variable prefix must not be null!");
1297 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(prefix));
1298 }
1299
1300 /**
1301 * Sets the variable prefix matcher currently in use.
1302 * <p>
1303 * The variable prefix is the character or characters that identify the start of a variable. This prefix is
1304 * expressed in terms of a matcher allowing advanced prefix matches.
1305 * </p>
1306 *
1307 * @param prefixMatcher the prefix matcher to use, null ignored
1308 * @return this, to enable chaining
1309 * @throws IllegalArgumentException if the prefix matcher is null
1310 */
1311 public StringSubstitutor setVariablePrefixMatcher(final StringMatcher prefixMatcher) {
1312 Validate.isTrue(prefixMatcher != null, "Variable prefix matcher must not be null!");
1313 this.prefixMatcher = prefixMatcher;
1314 return this;
1315 }
1316
1317 /**
1318 * Sets the VariableResolver that is used to lookup variables.
1319 *
1320 * @param variableResolver the VariableResolver
1321 * @return this, to enable chaining
1322 */
1323 public StringSubstitutor setVariableResolver(final StringLookup variableResolver) {
1324 this.variableResolver = variableResolver;
1325 return this;
1326 }
1327
1328 /**
1329 * Sets the variable suffix to use.
1330 * <p>
1331 * The variable suffix is the character or characters that identify the end of a variable. This method allows a
1332 * single character suffix to be easily set.
1333 * </p>
1334 *
1335 * @param suffix the suffix character to use
1336 * @return this, to enable chaining
1337 */
1338 public StringSubstitutor setVariableSuffix(final char suffix) {
1339 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.charMatcher(suffix));
1340 }
1341
1342 /**
1343 * Sets the variable suffix to use.
1344 * <p>
1345 * The variable suffix is the character or characters that identify the end of a variable. This method allows a
1346 * string suffix to be easily set.
1347 * </p>
1348 *
1349 * @param suffix the suffix for variables, not null
1350 * @return this, to enable chaining
1351 * @throws IllegalArgumentException if the suffix is null
1352 */
1353 public StringSubstitutor setVariableSuffix(final String suffix) {
1354 Validate.isTrue(suffix != null, "Variable suffix must not be null!");
1355 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(suffix));
1356 }
1357
1358 /**
1359 * Sets the variable suffix matcher currently in use.
1360 * <p>
1361 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed
1362 * in terms of a matcher allowing advanced suffix matches.
1363 * </p>
1364 *
1365 * @param suffixMatcher the suffix matcher to use, null ignored
1366 * @return this, to enable chaining
1367 * @throws IllegalArgumentException if the suffix matcher is null
1368 */
1369 public StringSubstitutor setVariableSuffixMatcher(final StringMatcher suffixMatcher) {
1370 Validate.isTrue(suffixMatcher != null, "Variable suffix matcher must not be null!");
1371 this.suffixMatcher = suffixMatcher;
1372 return this;
1373 }
1374
1375 /**
1376 * Internal method that substitutes the variables.
1377 * <p>
1378 * Most users of this class do not need to call this method. This method will be called automatically by another
1379 * (public) method.
1380 * </p>
1381 * <p>
1382 * Writers of subclasses can override this method if they need access to the substitution process at the start or
1383 * end.
1384 * </p>
1385 *
1386 * @param builder the string builder to substitute into, not null
1387 * @param offset the start offset within the builder, must be valid
1388 * @param length the length within the builder to be processed, must be valid
1389 * @return true if altered
1390 */
1391 protected boolean substitute(final TextStringBuilder builder, final int offset, final int length) {
1392 return substitute(builder, offset, length, null).altered;
1393 }
1394
1395 /**
1396 * Recursive handler for multiple levels of interpolation. This is the main interpolation method, which resolves the
1397 * values of all variable references contained in the passed in text.
1398 *
1399 * @param builder the string builder to substitute into, not null
1400 * @param offset the start offset within the builder, must be valid
1401 * @param length the length within the builder to be processed, must be valid
1402 * @param priorVariables the stack keeping track of the replaced variables, may be null
1403 * @return The result.
1404 * @throws IllegalArgumentException if variable is not found and <pre>isEnableUndefinedVariableException()==true</pre>
1405 * @since 1.9
1406 */
1407 private Result substitute(final TextStringBuilder builder, final int offset, final int length,
1408 List<String> priorVariables) {
1409 Objects.requireNonNull(builder, "builder");
1410 final StringMatcher prefixMatcher = getVariablePrefixMatcher();
1411 final StringMatcher suffixMatcher = getVariableSuffixMatcher();
1412 final char escapeCh = getEscapeChar();
1413 final StringMatcher valueDelimMatcher = getValueDelimiterMatcher();
1414 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
1415 final boolean substitutionInValuesDisabled = isDisableSubstitutionInValues();
1416 final boolean undefinedVariableException = isEnableUndefinedVariableException();
1417 final boolean preserveEscapes = isPreserveEscapes();
1418
1419 boolean altered = false;
1420 int lengthChange = 0;
1421 int bufEnd = offset + length;
1422 int pos = offset;
1423 int escPos = -1;
1424 outer: while (pos < bufEnd) {
1425 final int startMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd);
1426 if (startMatchLen == 0) {
1427 pos++;
1428 } else {
1429 // found variable start marker
1430 if (pos > offset && builder.charAt(pos - 1) == escapeCh) {
1431 // escape detected
1432 if (preserveEscapes) {
1433 // keep escape
1434 pos++;
1435 continue;
1436 }
1437 // mark esc ch for deletion if we find a complete variable
1438 escPos = pos - 1;
1439 }
1440 // find suffix
1441 int startPos = pos;
1442 pos += startMatchLen;
1443 int endMatchLen = 0;
1444 int nestedVarCount = 0;
1445 while (pos < bufEnd) {
1446 if (substitutionInVariablesEnabled && prefixMatcher.isMatch(builder, pos, offset, bufEnd) != 0) {
1447 // found a nested variable start
1448 endMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd);
1449 nestedVarCount++;
1450 pos += endMatchLen;
1451 continue;
1452 }
1453
1454 endMatchLen = suffixMatcher.isMatch(builder, pos, offset, bufEnd);
1455 if (endMatchLen == 0) {
1456 pos++;
1457 } else {
1458 // found variable end marker
1459 if (nestedVarCount == 0) {
1460 if (escPos >= 0) {
1461 // delete escape
1462 builder.deleteCharAt(escPos);
1463 escPos = -1;
1464 lengthChange--;
1465 altered = true;
1466 bufEnd--;
1467 pos = startPos + 1;
1468 startPos--;
1469 continue outer;
1470 }
1471 // get var name
1472 String varNameExpr = builder.midString(startPos + startMatchLen,
1473 pos - startPos - startMatchLen);
1474 if (substitutionInVariablesEnabled) {
1475 final TextStringBuilder bufName = new TextStringBuilder(varNameExpr);
1476 substitute(bufName, 0, bufName.length());
1477 varNameExpr = bufName.toString();
1478 }
1479 pos += endMatchLen;
1480 final int endPos = pos;
1481
1482 String varName = varNameExpr;
1483 String varDefaultValue = null;
1484
1485 if (valueDelimMatcher != null) {
1486 final char[] varNameExprChars = varNameExpr.toCharArray();
1487 int valueDelimiterMatchLen = 0;
1488 for (int i = 0; i < varNameExprChars.length; i++) {
1489 // if there's any nested variable when nested variable substitution disabled,
1490 // then stop resolving name and default value.
1491 if (!substitutionInVariablesEnabled && prefixMatcher.isMatch(varNameExprChars, i, i,
1492 varNameExprChars.length) != 0) {
1493 break;
1494 }
1495 if (valueDelimMatcher.isMatch(varNameExprChars, i, 0,
1496 varNameExprChars.length) != 0) {
1497 valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i, 0,
1498 varNameExprChars.length);
1499 varName = varNameExpr.substring(0, i);
1500 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
1501 break;
1502 }
1503 }
1504 }
1505
1506 // on the first call initialize priorVariables
1507 if (priorVariables == null) {
1508 priorVariables = new ArrayList<>();
1509 priorVariables.add(builder.midString(offset, length));
1510 }
1511
1512 // handle cyclic substitution
1513 checkCyclicSubstitution(varName, priorVariables);
1514 priorVariables.add(varName);
1515
1516 // resolve the variable
1517 String varValue = resolveVariable(varName, builder, startPos, endPos);
1518 if (varValue == null) {
1519 varValue = varDefaultValue;
1520 }
1521 if (varValue != null) {
1522 final int varLen = varValue.length();
1523 builder.replace(startPos, endPos, varValue);
1524 altered = true;
1525 int change = 0;
1526 if (!substitutionInValuesDisabled) { // recursive replace
1527 change = substitute(builder, startPos, varLen, priorVariables).lengthChange;
1528 }
1529 change = change + varLen - (endPos - startPos);
1530 pos += change;
1531 bufEnd += change;
1532 lengthChange += change;
1533 } else if (undefinedVariableException) {
1534 throw new IllegalArgumentException(
1535 String.format("Cannot resolve variable '%s' (enableSubstitutionInVariables=%s).",
1536 varName, substitutionInVariablesEnabled));
1537 }
1538
1539 // remove variable from the cyclic stack
1540 priorVariables.remove(priorVariables.size() - 1);
1541 break;
1542 }
1543 nestedVarCount--;
1544 pos += endMatchLen;
1545 }
1546 }
1547 }
1548 }
1549 return new Result(altered, lengthChange);
1550 }
1551
1552 /**
1553 * Returns a string representation of the object.
1554 *
1555 * @return a string representation of the object.
1556 * @since 1.11.0
1557 */
1558 @Override
1559 public String toString() {
1560 final StringBuilder builder = new StringBuilder();
1561 builder.append("StringSubstitutor [disableSubstitutionInValues=").append(disableSubstitutionInValues).append(", enableSubstitutionInVariables=")
1562 .append(enableSubstitutionInVariables).append(", enableUndefinedVariableException=").append(enableUndefinedVariableException)
1563 .append(", escapeChar=").append(escapeChar).append(", prefixMatcher=").append(prefixMatcher).append(", preserveEscapes=")
1564 .append(preserveEscapes).append(", suffixMatcher=").append(suffixMatcher).append(", valueDelimiterMatcher=").append(valueDelimiterMatcher)
1565 .append(", variableResolver=").append(variableResolver).append("]");
1566 return builder.toString();
1567 }
1568 }