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 * https://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 <strong>not</strong> 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_LOOPBACK_ADDRESS}</td>
349 * <td>{@link StringLookupFactory#loopbackAddressStringLookup()}</td>
350 * </tr>
351 * <tr>
352 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_PROPERTIES}</td>
353 * <td>{@link StringLookupFactory#propertiesStringLookup()}</td>
354 * </tr>
355 * <tr>
356 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_RESOURCE_BUNDLE}</td>
357 * <td>{@link StringLookupFactory#resourceBundleStringLookup()}</td>
358 * </tr>
359 * <tr>
360 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_SYS}</td>
361 * <td>{@link StringLookupFactory#systemPropertyStringLookup()}</td>
362 * </tr>
363 * <tr>
364 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_URL_DECODER}</td>
365 * <td>{@link StringLookupFactory#urlDecoderStringLookup()}</td>
366 * </tr>
367 * <tr>
368 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_URL_ENCODER}</td>
369 * <td>{@link StringLookupFactory#urlEncoderStringLookup()}</td>
370 * </tr>
371 * <tr>
372 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_XML}</td>
373 * <td>{@link StringLookupFactory#xmlStringLookup()}</td>
374 * </tr>
375 * <tr>
376 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_XML_DECODER}</td>
377 * <td>{@link StringLookupFactory#xmlDecoderStringLookup()}</td>
378 * </tr>
379 * <tr>
380 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_XML_ENCODER}</td>
381 * <td>{@link StringLookupFactory#xmlEncoderStringLookup()}</td>
382 * </tr>
383 * </table>
384 *
385 * @return A new instance using the interpolator string lookup.
386 * @see StringLookupFactory#interpolatorStringLookup()
387 * @since 1.8
388 */
389 public static StringSubstitutor createInterpolator() {
390 return new StringSubstitutor(StringLookupFactory.INSTANCE.interpolatorStringLookup());
391 }
392
393 /**
394 * Replaces all the occurrences of variables in the given source object with their matching values from the map.
395 *
396 * @param <V> The type of the values in the map
397 * @param source The source text containing the variables to substitute, null returns null
398 * @param valueMap The map with the values, may be null
399 * @return The result of the replace operation
400 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
401 */
402 public static <V> String replace(final Object source, final Map<String, V> valueMap) {
403 return new StringSubstitutor(valueMap).replace(source);
404 }
405
406 /**
407 * Replaces all the occurrences of variables in the given source object with their matching values from the map.
408 * This method allows to specify a custom variable prefix and suffix
409 *
410 * @param <V> The type of the values in the map
411 * @param source The source text containing the variables to substitute, null returns null
412 * @param valueMap The map with the values, may be null
413 * @param prefix The prefix of variables, not null
414 * @param suffix The suffix of variables, not null
415 * @return The result of the replace operation
416 * @throws IllegalArgumentException if the prefix or suffix is null
417 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
418 */
419 public static <V> String replace(final Object source, final Map<String, V> valueMap, final String prefix,
420 final String suffix) {
421 return new StringSubstitutor(valueMap, prefix, suffix).replace(source);
422 }
423
424 /**
425 * Replaces all the occurrences of variables in the given source object with their matching values from the
426 * properties.
427 *
428 * @param source The source text containing the variables to substitute, null returns null
429 * @param valueProperties The properties with values, may be null
430 * @return The result of the replace operation
431 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
432 */
433 public static String replace(final Object source, final Properties valueProperties) {
434 if (valueProperties == null) {
435 return source.toString();
436 }
437 return replace(source, valueProperties.stringPropertyNames().stream().collect(Collectors.toMap(Function.identity(), valueProperties::getProperty)));
438 }
439
440 /**
441 * Replaces all the occurrences of variables in the given source object with their matching values from the system
442 * properties.
443 *
444 * @param source The source text containing the variables to substitute, null returns null
445 * @return The result of the replace operation
446 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
447 */
448 public static String replaceSystemProperties(final Object source) {
449 return new StringSubstitutor(StringLookupFactory.INSTANCE.systemPropertyStringLookup()).replace(source);
450 }
451
452 /**
453 * The flag whether substitution in variable values is disabled.
454 */
455 private boolean disableSubstitutionInValues;
456
457 /**
458 * The flag whether substitution in variable names is enabled.
459 */
460 private boolean enableSubstitutionInVariables;
461
462 /**
463 * The flag whether exception should be thrown on undefined variable.
464 */
465 private boolean failOnUndefinedVariable;
466
467 /**
468 * Stores the escape character.
469 */
470 private char escapeChar;
471
472 /**
473 * Stores the variable prefix.
474 */
475 private StringMatcher prefixMatcher;
476
477 /**
478 * Whether escapes should be preserved. Default is false;
479 */
480 private boolean preserveEscapes;
481
482 /**
483 * Stores the variable suffix.
484 */
485 private StringMatcher suffixMatcher;
486
487 /**
488 * Stores the default variable value delimiter.
489 */
490 private StringMatcher valueDelimiterMatcher;
491
492 /**
493 * Variable resolution is delegated to an implementor of {@link StringLookup}.
494 */
495 private StringLookup variableResolver;
496
497 /**
498 * Constructs a new instance with defaults for variable prefix and suffix and the escaping character.
499 */
500 public StringSubstitutor() {
501 this(null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
502 }
503
504 /**
505 * Constructs a new initialized instance. Uses defaults for variable prefix and suffix and the escaping
506 * character.
507 *
508 * @param <V> The type of the values in the map.
509 * @param valueMap The map with the variables' values, may be null.
510 */
511 public <V> StringSubstitutor(final Map<String, V> valueMap) {
512 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
513 }
514
515 /**
516 * Constructs a new initialized instance. Uses a default escaping character.
517 *
518 * @param <V> The type of the values in the map.
519 * @param valueMap The map with the variables' values, may be null.
520 * @param prefix The prefix for variables, not null.
521 * @param suffix The suffix for variables, not null.
522 * @throws IllegalArgumentException if the prefix or suffix is null.
523 */
524 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix) {
525 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE);
526 }
527
528 /**
529 * Constructs a new initialized instance.
530 *
531 * @param <V> The type of the values in the map.
532 * @param valueMap The map with the variables' values, may be null.
533 * @param prefix The prefix for variables, not null.
534 * @param suffix The suffix for variables, not null.
535 * @param escape The escape character.
536 * @throws IllegalArgumentException if the prefix or suffix is null.
537 */
538 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
539 final char escape) {
540 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, escape);
541 }
542
543 /**
544 * Constructs a new initialized instance.
545 *
546 * @param <V> The type of the values in the map.
547 * @param valueMap The map with the variables' values, may be null.
548 * @param prefix The prefix for variables, not null.
549 * @param suffix The suffix for variables, not null.
550 * @param escape The escape character.
551 * @param valueDelimiter The variable default value delimiter, may be null.
552 * @throws IllegalArgumentException if the prefix or suffix is null.
553 */
554 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
555 final char escape, final String valueDelimiter) {
556 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, escape, valueDelimiter);
557 }
558
559 /**
560 * Constructs a new initialized instance.
561 *
562 * @param variableResolver The variable resolver, may be null
563 */
564 public StringSubstitutor(final StringLookup variableResolver) {
565 this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
566 }
567
568 /**
569 * Constructs a new initialized instance.
570 *
571 * @param variableResolver The variable resolver, may be null.
572 * @param prefix The prefix for variables, not null.
573 * @param suffix The suffix for variables, not null.
574 * @param escape The escape character.
575 * @throws IllegalArgumentException if the prefix or suffix is null.
576 */
577 public StringSubstitutor(final StringLookup variableResolver, final String prefix, final String suffix,
578 final char escape) {
579 setVariableResolver(variableResolver);
580 setVariablePrefix(prefix);
581 setVariableSuffix(suffix);
582 setEscapeChar(escape);
583 setValueDelimiterMatcher(DEFAULT_VALUE_DELIMITER);
584 }
585
586 /**
587 * Constructs a new initialized instance.
588 *
589 * @param variableResolver The variable resolver, may be null.
590 * @param prefix The prefix for variables, not null.
591 * @param suffix The suffix for variables, not null.
592 * @param escape The escape character.
593 * @param valueDelimiter The variable default value delimiter string, may be null.
594 * @throws IllegalArgumentException if the prefix or suffix is null.
595 */
596 public StringSubstitutor(final StringLookup variableResolver, final String prefix, final String suffix,
597 final char escape, final String valueDelimiter) {
598 setVariableResolver(variableResolver);
599 setVariablePrefix(prefix);
600 setVariableSuffix(suffix);
601 setEscapeChar(escape);
602 setValueDelimiter(valueDelimiter);
603 }
604
605 /**
606 * Constructs a new initialized instance.
607 *
608 * @param variableResolver The variable resolver, may be null
609 * @param prefixMatcher The prefix for variables, not null.
610 * @param suffixMatcher The suffix for variables, not null.
611 * @param escape The escape character.
612 * @throws IllegalArgumentException if the prefix or suffix is null.
613 */
614 public StringSubstitutor(final StringLookup variableResolver, final StringMatcher prefixMatcher,
615 final StringMatcher suffixMatcher, final char escape) {
616 this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER);
617 }
618
619 /**
620 * Constructs a new initialized instance.
621 *
622 * @param variableResolver The variable resolver, may be null
623 * @param prefixMatcher The prefix for variables, not null
624 * @param suffixMatcher The suffix for variables, not null
625 * @param escape The escape character
626 * @param valueDelimiterMatcher The variable default value delimiter matcher, may be null
627 * @throws IllegalArgumentException if the prefix or suffix is null
628 */
629 public StringSubstitutor(final StringLookup variableResolver, final StringMatcher prefixMatcher,
630 final StringMatcher suffixMatcher, final char escape, final StringMatcher valueDelimiterMatcher) {
631 setVariableResolver(variableResolver);
632 setVariablePrefixMatcher(prefixMatcher);
633 setVariableSuffixMatcher(suffixMatcher);
634 setEscapeChar(escape);
635 setValueDelimiterMatcher(valueDelimiterMatcher);
636 }
637
638 /**
639 * Creates a new instance based on the given.
640 *
641 * @param other The StringSubstitutor used as the source.
642 * @since 1.9
643 */
644 public StringSubstitutor(final StringSubstitutor other) {
645 disableSubstitutionInValues = other.isDisableSubstitutionInValues();
646 enableSubstitutionInVariables = other.isEnableSubstitutionInVariables();
647 failOnUndefinedVariable = other.isEnableUndefinedVariableException();
648 escapeChar = other.getEscapeChar();
649 prefixMatcher = other.getVariablePrefixMatcher();
650 preserveEscapes = other.isPreserveEscapes();
651 suffixMatcher = other.getVariableSuffixMatcher();
652 valueDelimiterMatcher = other.getValueDelimiterMatcher();
653 variableResolver = other.getStringLookup();
654 }
655
656 /**
657 * Checks if the specified variable is already in the stack (list) of variables.
658 *
659 * @param varName The variable name to check
660 * @param priorVariables The list of prior variables
661 */
662 private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) {
663 if (!priorVariables.contains(varName)) {
664 return;
665 }
666 final TextStringBuilder buf = new TextStringBuilder(256);
667 buf.append("Infinite loop in property interpolation of ");
668 buf.append(priorVariables.remove(0));
669 buf.append(": ");
670 buf.appendWithSeparators(priorVariables, "->");
671 throw new IllegalStateException(buf.toString());
672 }
673
674 /**
675 * Returns the escape character.
676 *
677 * @return The character used for escaping variable references.
678 */
679 public char getEscapeChar() {
680 return escapeChar;
681 }
682
683 /**
684 * Gets the StringLookup that is used to lookup variables.
685 *
686 * @return The StringLookup.
687 */
688 public StringLookup getStringLookup() {
689 return variableResolver;
690 }
691
692 /**
693 * Gets the variable default value delimiter matcher currently in use.
694 * <p>
695 * The variable default value delimiter is the character or characters that delimit the variable name and the
696 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default
697 * value delimiter matches.
698 * </p>
699 * <p>
700 * If it returns null, then the variable default value resolution is disabled.
701 *
702 * @return The variable default value delimiter matcher in use, may be null.
703 */
704 public StringMatcher getValueDelimiterMatcher() {
705 return valueDelimiterMatcher;
706 }
707
708 /**
709 * Gets the variable prefix matcher currently in use.
710 * <p>
711 * The variable prefix is the character or characters that identify the start of a variable. This prefix is
712 * expressed in terms of a matcher allowing advanced prefix matches.
713 * </p>
714 *
715 * @return The prefix matcher in use
716 */
717 public StringMatcher getVariablePrefixMatcher() {
718 return prefixMatcher;
719 }
720
721 /**
722 * Gets the variable suffix matcher currently in use.
723 * <p>
724 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed
725 * in terms of a matcher allowing advanced suffix matches.
726 * </p>
727 *
728 * @return The suffix matcher in use
729 */
730 public StringMatcher getVariableSuffixMatcher() {
731 return suffixMatcher;
732 }
733
734 /**
735 * Checks whether the specified buffer contains a variable suffix after the given position.
736 *
737 * @param builder The string builder to check, not null.
738 * @param pos The position to start checking from.
739 * @param offset The start offset within the builder, must be valid.
740 * @param bufEnd The end offset within the builder, must be valid.
741 * @param suffixMatcher The suffix matcher to use, not null.
742 * @return true if a suffix is found after the given position.
743 */
744 private boolean hasLaterSuffix(final TextStringBuilder builder, int pos, final int offset, final int bufEnd, final StringMatcher suffixMatcher) {
745 while (pos < bufEnd) {
746 if (suffixMatcher.isMatch(builder, pos, offset, bufEnd) != 0) {
747 return true;
748 }
749 pos++;
750 }
751 return false;
752 }
753
754 /**
755 * Returns a flag whether substitution is disabled in variable values.If set to <strong>true</strong>, the values of variables
756 * can contain other variables will not be processed and substituted original variable is evaluated, e.g.
757 *
758 * <pre>
759 * Map<String, String> valuesMap = new HashMap<>();
760 * valuesMap.put("name", "Douglas ${surname}");
761 * valuesMap.put("surname", "Crockford");
762 * String templateString = "Hi ${name}";
763 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
764 * String resolvedString = sub.replace(templateString);
765 * </pre>
766 *
767 * yielding:
768 *
769 * <pre>
770 * Hi Douglas ${surname}
771 * </pre>
772 *
773 * @return The substitution in variable values flag.
774 */
775 public boolean isDisableSubstitutionInValues() {
776 return disableSubstitutionInValues;
777 }
778
779 /**
780 * Returns a flag whether substitution is done in variable names.
781 *
782 * @return The substitution in variable names flag.
783 */
784 public boolean isEnableSubstitutionInVariables() {
785 return enableSubstitutionInVariables;
786 }
787
788 /**
789 * Returns a flag whether exception can be thrown upon undefined variable.
790 *
791 * @return The fail on undefined variable flag.
792 */
793 public boolean isEnableUndefinedVariableException() {
794 return failOnUndefinedVariable;
795 }
796
797 /**
798 * Returns the flag controlling whether escapes are preserved during substitution.
799 *
800 * @return The preserve escape flag.
801 */
802 public boolean isPreserveEscapes() {
803 return preserveEscapes;
804 }
805
806 /**
807 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
808 * array as a template. The array is not altered by this method.
809 *
810 * @param source The character array to replace in, not altered, null returns null.
811 * @return The result of the replace operation.
812 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
813 */
814 public String replace(final char[] source) {
815 if (source == null) {
816 return null;
817 }
818 final TextStringBuilder buf = new TextStringBuilder(source.length).append(source);
819 substitute(buf, 0, source.length);
820 return buf.toString();
821 }
822
823 /**
824 * 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
825 * altered by this method.
826 * <p>
827 * Only the specified portion of the array will be processed. The rest of the array is not processed, and is not returned.
828 * </p>
829 *
830 * @param source The character array to replace in, not altered, null returns null.
831 * @param offset The start offset within the array, must be valid.
832 * @param length The length within the array to be processed, must be valid.
833 * @return The result of the replace operation.
834 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
835 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the range {@code 0 <= offset <= chars.length}.
836 * @throws StringIndexOutOfBoundsException if {@code length < 0}.
837 * @throws StringIndexOutOfBoundsException if {@code offset + length > chars.length}.
838 */
839 public String replace(final char[] source, final int offset, final int length) {
840 if (source == null) {
841 return null;
842 }
843 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
844 substitute(buf, 0, length);
845 return buf.toString();
846 }
847
848 /**
849 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as
850 * a template. The source is not altered by this method.
851 *
852 * @param source The buffer to use as a template, not changed, null returns null.
853 * @return The result of the replace operation.
854 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
855 */
856 public String replace(final CharSequence source) {
857 if (source == null) {
858 return null;
859 }
860 return replace(source, 0, source.length());
861 }
862
863 /**
864 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as
865 * a template. The source is not altered by this method.
866 * <p>
867 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not
868 * returned.
869 * </p>
870 *
871 * @param source The buffer to use as a template, not changed, null returns null.
872 * @param offset The start offset within the array, must be valid.
873 * @param length The length within the array to be processed, must be valid.
874 * @return The result of the replace operation.
875 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
876 */
877 public String replace(final CharSequence source, final int offset, final int length) {
878 if (source == null) {
879 return null;
880 }
881 final TextStringBuilder buf = new TextStringBuilder(length).append(source.toString(), offset, length);
882 substitute(buf, 0, length);
883 return buf.toString();
884 }
885
886 /**
887 * Replaces all the occurrences of variables in the given source object with their matching values from the
888 * resolver. The input source object is converted to a string using {@code toString} and is not altered.
889 *
890 * @param source The source to replace in, null returns null.
891 * @return The result of the replace operation.
892 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true.
893 */
894 public String replace(final Object source) {
895 if (source == null) {
896 return null;
897 }
898 final TextStringBuilder buf = new TextStringBuilder().append(source);
899 substitute(buf, 0, buf.length());
900 return buf.toString();
901 }
902
903 /**
904 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
905 * string as a template.
906 *
907 * @param source The string to replace in, null returns null.
908 * @return The result of the replace operation.
909 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
910 */
911 public String replace(final String source) {
912 if (source == null) {
913 return null;
914 }
915 final TextStringBuilder buf = new TextStringBuilder(source);
916 if (!substitute(buf, 0, source.length())) {
917 return source;
918 }
919 return buf.toString();
920 }
921
922 /**
923 * Replaces all the occurrences of variables with their matching values from the resolver using the given source string as a template.
924 * <p>
925 * Only the specified portion of the string will be processed. The rest of the string is not processed, and is not returned.
926 * </p>
927 *
928 * @param source The string to replace in, null returns null.
929 * @param offset The start offset within the source, must be valid.
930 * @param length The length within the source to be processed, must be valid.
931 * @return The result of the replace operation.
932 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
933 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the range {@code 0 <= offset <= source.length()}.
934 * @throws StringIndexOutOfBoundsException if {@code length < 0}.
935 * @throws StringIndexOutOfBoundsException if {@code offset + length > source.length()}.
936 */
937 public String replace(final String source, final int offset, final int length) {
938 if (source == null) {
939 return null;
940 }
941 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
942 if (!substitute(buf, 0, length)) {
943 return source.substring(offset, offset + length);
944 }
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 *
952 * @param source The buffer to use as a template, not changed, null returns null.
953 * @return The result of the replace operation.
954 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
955 */
956 public String replace(final StringBuffer source) {
957 if (source == null) {
958 return null;
959 }
960 final TextStringBuilder buf = new TextStringBuilder(source.length()).append(source);
961 substitute(buf, 0, buf.length());
962 return buf.toString();
963 }
964
965 /**
966 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
967 * buffer as a template. The buffer is not altered by this method.
968 * <p>
969 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not
970 * returned.
971 * </p>
972 *
973 * @param source The buffer to use as a template, not changed, null returns null.
974 * @param offset The start offset within the source, must be valid.
975 * @param length The length within the source to be processed, must be valid.
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 StringBuffer source, final int offset, final int length) {
980 if (source == null) {
981 return null;
982 }
983 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
984 substitute(buf, 0, length);
985 return buf.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 *
992 * @param source The builder to use as a template, not changed, null returns null.
993 * @return The result of the replace operation.
994 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
995 */
996 public String replace(final TextStringBuilder source) {
997 if (source == null) {
998 return null;
999 }
1000 final TextStringBuilder builder = new TextStringBuilder(source.length()).append(source);
1001 substitute(builder, 0, builder.length());
1002 return builder.toString();
1003 }
1004
1005 /**
1006 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
1007 * builder as a template. The builder is not altered by this method.
1008 * <p>
1009 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, and is not
1010 * returned.
1011 * </p>
1012 *
1013 * @param source The builder to use as a template, not changed, null returns null.
1014 * @param offset The start offset within the source, must be valid.
1015 * @param length The length within the source to be processed, must be valid.
1016 * @return The result of the replace operation.
1017 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
1018 */
1019 public String replace(final TextStringBuilder source, final int offset, final int length) {
1020 if (source == null) {
1021 return null;
1022 }
1023 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1024 substitute(buf, 0, length);
1025 return buf.toString();
1026 }
1027
1028 /**
1029 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1030 * resolver. The buffer is updated with the result.
1031 *
1032 * @param source The buffer to replace in, updated, null returns zero.
1033 * @return true if altered
1034 */
1035 public boolean replaceIn(final StringBuffer source) {
1036 if (source == null) {
1037 return false;
1038 }
1039 return replaceIn(source, 0, source.length());
1040 }
1041
1042 /**
1043 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1044 * resolver. The buffer is updated with the result.
1045 * <p>
1046 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is
1047 * not deleted.
1048 * </p>
1049 *
1050 * @param source The buffer to replace in, updated, null returns zero.
1051 * @param offset The start offset within the source, must be valid.
1052 * @param length The length within the source to be processed, must be valid.
1053 * @return true if altered.
1054 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
1055 */
1056 public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
1057 if (source == null) {
1058 return false;
1059 }
1060 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1061 if (!substitute(buf, 0, length)) {
1062 return false;
1063 }
1064 source.replace(offset, offset + length, buf.toString());
1065 return true;
1066 }
1067
1068 /**
1069 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1070 * resolver. The buffer is updated with the result.
1071 *
1072 * @param source The buffer to replace in, updated, null returns zero.
1073 * @return true if altered.
1074 */
1075 public boolean replaceIn(final StringBuilder source) {
1076 if (source == null) {
1077 return false;
1078 }
1079 return replaceIn(source, 0, source.length());
1080 }
1081
1082 /**
1083 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1084 * resolver. The builder is updated with the result.
1085 * <p>
1086 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is
1087 * not deleted.
1088 * </p>
1089 *
1090 * @param source The buffer to replace in, updated, null returns zero.
1091 * @param offset The start offset within the source, must be valid.
1092 * @param length The length within the source to be processed, must be valid.
1093 * @return true if altered.
1094 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
1095 */
1096 public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
1097 if (source == null) {
1098 return false;
1099 }
1100 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1101 if (!substitute(buf, 0, length)) {
1102 return false;
1103 }
1104 source.replace(offset, offset + length, buf.toString());
1105 return true;
1106 }
1107
1108 /**
1109 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1110 * resolver.
1111 *
1112 * @param source The builder to replace in, updated, null returns zero.
1113 * @return true if altered.
1114 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
1115 */
1116 public boolean replaceIn(final TextStringBuilder source) {
1117 if (source == null) {
1118 return false;
1119 }
1120 return substitute(source, 0, source.length());
1121 }
1122
1123 /**
1124 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1125 * resolver.
1126 * <p>
1127 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, but it is
1128 * not deleted.
1129 * </p>
1130 *
1131 * @param source The builder to replace in, null returns zero.
1132 * @param offset The start offset within the source, must be valid.
1133 * @param length The length within the source to be processed, must be valid.
1134 * @return true if altered.
1135 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
1136 */
1137 public boolean replaceIn(final TextStringBuilder source, final int offset, final int length) {
1138 if (source == null) {
1139 return false;
1140 }
1141 return substitute(source, offset, length);
1142 }
1143
1144 /**
1145 * Internal method that resolves the value of a variable.
1146 * <p>
1147 * Most users of this class do not need to call this method. This method is called automatically by the substitution
1148 * process.
1149 * </p>
1150 * <p>
1151 * Writers of subclasses can override this method if they need to alter how each substitution occurs. The method is
1152 * passed the variable's name and must return the corresponding value. This implementation uses the
1153 * {@link #getStringLookup()} with the variable's name as the key.
1154 * </p>
1155 *
1156 * @param variableName The name of the variable, not null.
1157 * @param buf The buffer where the substitution is occurring, not null.
1158 * @param startPos The start position of the variable including the prefix, valid.
1159 * @param endPos The end position of the variable including the suffix, valid.
1160 * @return The variable's value or {@code null} if the variable is unknown.
1161 */
1162 protected String resolveVariable(final String variableName, final TextStringBuilder buf, final int startPos,
1163 final int endPos) {
1164 final StringLookup resolver = getStringLookup();
1165 if (resolver == null) {
1166 return null;
1167 }
1168 return resolver.apply(variableName);
1169 }
1170
1171 /**
1172 * Sets a flag whether substitution is done in variable values (recursive).
1173 *
1174 * @param disableSubstitutionInValues true if substitution in variable value are disabled.
1175 * @return {@code this} instance.
1176 */
1177 public StringSubstitutor setDisableSubstitutionInValues(final boolean disableSubstitutionInValues) {
1178 this.disableSubstitutionInValues = disableSubstitutionInValues;
1179 return this;
1180 }
1181
1182 /**
1183 * Sets a flag whether substitution is done in variable names. If set to <strong>true</strong>, the names of variables can
1184 * contain other variables which are processed first before the original variable is evaluated, e.g.
1185 * {@code ${jre-${java.version}}}. The default value is <strong>false</strong>.
1186 *
1187 * @param enableSubstitutionInVariables The new value of the flag.
1188 * @return {@code this} instance.
1189 */
1190 public StringSubstitutor setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) {
1191 this.enableSubstitutionInVariables = enableSubstitutionInVariables;
1192 return this;
1193 }
1194
1195 /**
1196 * Sets a flag whether exception should be thrown if any variable is undefined.
1197 *
1198 * @param failOnUndefinedVariable true if exception should be thrown on undefined variable.
1199 * @return {@code this} instance.
1200 */
1201 public StringSubstitutor setEnableUndefinedVariableException(final boolean failOnUndefinedVariable) {
1202 this.failOnUndefinedVariable = failOnUndefinedVariable;
1203 return this;
1204 }
1205
1206 /**
1207 * Sets the escape character. If this character is placed before a variable reference in the source text, this
1208 * variable will be ignored.
1209 *
1210 * @param escapeChar The escape character (0 for disabling escaping).
1211 * @return {@code this} instance.
1212 */
1213 public StringSubstitutor setEscapeChar(final char escapeChar) {
1214 this.escapeChar = escapeChar;
1215 return this;
1216 }
1217
1218 /**
1219 * Sets a flag controlling whether escapes are preserved during substitution. If set to <strong>true</strong>, the escape
1220 * character is retained during substitution (e.g. {@code $${this-is-escaped}} remains {@code $${this-is-escaped}}).
1221 * If set to <strong>false</strong>, the escape character is removed during substitution (e.g. {@code $${this-is-escaped}}
1222 * becomes {@code ${this-is-escaped}}). The default value is <strong>false</strong>
1223 *
1224 * @param preserveEscapes true if escapes are to be preserved.
1225 * @return {@code this} instance.
1226 */
1227 public StringSubstitutor setPreserveEscapes(final boolean preserveEscapes) {
1228 this.preserveEscapes = preserveEscapes;
1229 return this;
1230 }
1231
1232 /**
1233 * Sets the variable default value delimiter to use.
1234 * <p>
1235 * The variable default value delimiter is the character or characters that delimit the variable name and the
1236 * variable default value. This method allows a single character variable default value delimiter to be easily set.
1237 * </p>
1238 *
1239 * @param valueDelimiter The variable default value delimiter character to use.
1240 * @return {@code this} instance.
1241 */
1242 public StringSubstitutor setValueDelimiter(final char valueDelimiter) {
1243 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.charMatcher(valueDelimiter));
1244 }
1245
1246 /**
1247 * Sets the variable default value delimiter to use.
1248 * <p>
1249 * The variable default value delimiter is the character or characters that delimit the variable name and the
1250 * variable default value. This method allows a string variable default value delimiter to be easily set.
1251 * </p>
1252 * <p>
1253 * If the {@code valueDelimiter} is null or empty string, then the variable default value resolution becomes
1254 * disabled.
1255 * </p>
1256 *
1257 * @param valueDelimiter The variable default value delimiter string to use, may be null or empty.
1258 * @return {@code this} instance.
1259 */
1260 public StringSubstitutor setValueDelimiter(final String valueDelimiter) {
1261 if (valueDelimiter == null || valueDelimiter.isEmpty()) {
1262 setValueDelimiterMatcher(null);
1263 return this;
1264 }
1265 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.stringMatcher(valueDelimiter));
1266 }
1267
1268 /**
1269 * Sets the variable default value delimiter matcher to use.
1270 * <p>
1271 * The variable default value delimiter is the character or characters that delimit the variable name and the
1272 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default
1273 * value delimiter matches.
1274 * </p>
1275 * <p>
1276 * If the {@code valueDelimiterMatcher} is null, then the variable default value resolution becomes disabled.
1277 * </p>
1278 *
1279 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null.
1280 * @return {@code this} instance.
1281 */
1282 public StringSubstitutor setValueDelimiterMatcher(final StringMatcher valueDelimiterMatcher) {
1283 this.valueDelimiterMatcher = valueDelimiterMatcher;
1284 return this;
1285 }
1286
1287 /**
1288 * Sets the variable prefix to use.
1289 * <p>
1290 * The variable prefix is the character or characters that identify the start of a variable. This method allows a
1291 * single character prefix to be easily set.
1292 * </p>
1293 *
1294 * @param prefix The prefix character to use.
1295 * @return {@code this} instance.
1296 */
1297 public StringSubstitutor setVariablePrefix(final char prefix) {
1298 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.charMatcher(prefix));
1299 }
1300
1301 /**
1302 * Sets the variable prefix to use.
1303 * <p>
1304 * The variable prefix is the character or characters that identify the start of a variable. This method allows a
1305 * string prefix to be easily set.
1306 * </p>
1307 *
1308 * @param prefix The prefix for variables, not null.
1309 * @return {@code this} instance.
1310 * @throws IllegalArgumentException if the prefix is null.
1311 */
1312 public StringSubstitutor setVariablePrefix(final String prefix) {
1313 Validate.isTrue(prefix != null, "Variable prefix must not be null!");
1314 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(prefix));
1315 }
1316
1317 /**
1318 * Sets the variable prefix matcher currently in use.
1319 * <p>
1320 * The variable prefix is the character or characters that identify the start of a variable. This prefix is
1321 * expressed in terms of a matcher allowing advanced prefix matches.
1322 * </p>
1323 *
1324 * @param prefixMatcher The prefix matcher to use, null ignored.
1325 * @return {@code this} instance.
1326 * @throws IllegalArgumentException if the prefix matcher is null.
1327 */
1328 public StringSubstitutor setVariablePrefixMatcher(final StringMatcher prefixMatcher) {
1329 Validate.isTrue(prefixMatcher != null, "Variable prefix matcher must not be null!");
1330 this.prefixMatcher = prefixMatcher;
1331 return this;
1332 }
1333
1334 /**
1335 * Sets the VariableResolver that is used to lookup variables.
1336 *
1337 * @param variableResolver The VariableResolver.
1338 * @return {@code this} instance.
1339 */
1340 public StringSubstitutor setVariableResolver(final StringLookup variableResolver) {
1341 this.variableResolver = variableResolver;
1342 return this;
1343 }
1344
1345 /**
1346 * Sets the variable suffix to use.
1347 * <p>
1348 * The variable suffix is the character or characters that identify the end of a variable. This method allows a
1349 * single character suffix to be easily set.
1350 * </p>
1351 *
1352 * @param suffix The suffix character to use.
1353 * @return {@code this} instance.
1354 */
1355 public StringSubstitutor setVariableSuffix(final char suffix) {
1356 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.charMatcher(suffix));
1357 }
1358
1359 /**
1360 * Sets the variable suffix to use.
1361 * <p>
1362 * The variable suffix is the character or characters that identify the end of a variable. This method allows a
1363 * string suffix to be easily set.
1364 * </p>
1365 *
1366 * @param suffix The suffix for variables, not null.
1367 * @return {@code this} instance.
1368 * @throws IllegalArgumentException if the suffix is null.
1369 */
1370 public StringSubstitutor setVariableSuffix(final String suffix) {
1371 Validate.isTrue(suffix != null, "Variable suffix must not be null!");
1372 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(suffix));
1373 }
1374
1375 /**
1376 * Sets the variable suffix matcher currently in use.
1377 * <p>
1378 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed
1379 * in terms of a matcher allowing advanced suffix matches.
1380 * </p>
1381 *
1382 * @param suffixMatcher The suffix matcher to use, null ignored.
1383 * @return {@code this} instance.
1384 * @throws IllegalArgumentException if the suffix matcher is null.
1385 */
1386 public StringSubstitutor setVariableSuffixMatcher(final StringMatcher suffixMatcher) {
1387 Validate.isTrue(suffixMatcher != null, "Variable suffix matcher must not be null!");
1388 this.suffixMatcher = suffixMatcher;
1389 return this;
1390 }
1391
1392 /**
1393 * Internal method that substitutes the variables.
1394 * <p>
1395 * Most users of this class do not need to call this method. This method will be called automatically by another
1396 * (public) method.
1397 * </p>
1398 * <p>
1399 * Writers of subclasses can override this method if they need access to the substitution process at the start or
1400 * end.
1401 * </p>
1402 *
1403 * @param builder The string builder to substitute into, not null.
1404 * @param offset The start offset within the builder, must be valid.
1405 * @param length The length within the builder to be processed, must be valid.
1406 * @return true if altered.
1407 */
1408 protected boolean substitute(final TextStringBuilder builder, final int offset, final int length) {
1409 return substitute(builder, offset, length, null).altered;
1410 }
1411
1412 /**
1413 * Recursive handler for multiple levels of interpolation. This is the main interpolation method, which resolves the values of all variable references
1414 * contained in the passed in text.
1415 *
1416 * @param builder The string builder to substitute into, not null.
1417 * @param offset The start offset within the builder, must be valid.
1418 * @param length The length within the builder to be processed, must be valid.
1419 * @param priorVariables The stack keeping track of the replaced variables, may be null.
1420 * @return The result.
1421 * @throws IllegalArgumentException if variable is not found and <code>isEnableUndefinedVariableException() == true</code>.
1422 * @since 1.9
1423 */
1424 private Result substitute(final TextStringBuilder builder, final int offset, final int length, List<String> priorVariables) {
1425 Objects.requireNonNull(builder, "builder");
1426 final StringMatcher prefixMatcher = getVariablePrefixMatcher();
1427 final StringMatcher suffixMatcher = getVariableSuffixMatcher();
1428 final char escapeCh = getEscapeChar();
1429 final StringMatcher valueDelimMatcher = getValueDelimiterMatcher();
1430 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
1431 final boolean substitutionInValuesDisabled = isDisableSubstitutionInValues();
1432 final boolean undefinedVariableException = isEnableUndefinedVariableException();
1433 final boolean preserveEscapes = isPreserveEscapes();
1434 boolean altered = false;
1435 int lengthChange = 0;
1436 int bufEnd = offset + length;
1437 int pos = offset;
1438 int escPos = -1;
1439 outer: while (pos < bufEnd) {
1440 final int startMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd);
1441 if (startMatchLen == 0) {
1442 pos++;
1443 } else {
1444 // found variable start marker
1445 if (pos > offset && builder.charAt(pos - 1) == escapeCh) {
1446 // escape detected
1447 if (preserveEscapes) {
1448 // keep escape
1449 pos++;
1450 continue;
1451 }
1452 // mark esc ch for deletion if we find a complete variable
1453 escPos = pos - 1;
1454 }
1455 // find suffix
1456 int startPos = pos;
1457 pos += startMatchLen;
1458 int endMatchLen = 0;
1459 int nestedVarCount = 0;
1460 while (pos < bufEnd) {
1461 if (substitutionInVariablesEnabled && prefixMatcher.isMatch(builder, pos, offset, bufEnd) != 0) {
1462 // found a nested variable start
1463 endMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd);
1464 nestedVarCount++;
1465 pos += endMatchLen;
1466 continue;
1467 }
1468 endMatchLen = suffixMatcher.isMatch(builder, pos, offset, bufEnd);
1469 if (endMatchLen == 0) {
1470 pos++;
1471 } else {
1472 // found variable end marker
1473 if (nestedVarCount == 0) {
1474 if (escPos >= 0) {
1475 final boolean escapedVariableStartsWithNestedPrefix = prefixMatcher.isMatch(builder, startPos + startMatchLen, offset,
1476 bufEnd) != 0;
1477 final boolean hasOuterSuffix = hasLaterSuffix(builder, pos + endMatchLen, offset, bufEnd, suffixMatcher);
1478 pos = escapedVariableStartsWithNestedPrefix && !hasOuterSuffix ? escPos : startPos + 1;
1479 // delete escape
1480 builder.deleteCharAt(escPos);
1481 escPos = -1;
1482 lengthChange--;
1483 altered = true;
1484 bufEnd--;
1485 startPos--;
1486 continue outer;
1487 }
1488 // get var name
1489 String varNameExpr = builder.midString(startPos + startMatchLen, pos - startPos - startMatchLen);
1490 if (substitutionInVariablesEnabled) {
1491 final TextStringBuilder bufName = new TextStringBuilder(varNameExpr);
1492 substitute(bufName, 0, bufName.length());
1493 varNameExpr = bufName.toString();
1494 }
1495 pos += endMatchLen;
1496 final int endPos = pos;
1497 String varName = varNameExpr;
1498 String varDefaultValue = null;
1499 if (valueDelimMatcher != null) {
1500 final char[] varNameExprChars = varNameExpr.toCharArray();
1501 int valueDelimiterMatchLen = 0;
1502 for (int i = 0; i < varNameExprChars.length; i++) {
1503 // if there's any nested variable when nested variable substitution disabled,
1504 // then stop resolving name and default value.
1505 if (!substitutionInVariablesEnabled && prefixMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) {
1506 break;
1507 }
1508 if (valueDelimMatcher.isMatch(varNameExprChars, i, 0, varNameExprChars.length) != 0) {
1509 valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i, 0, varNameExprChars.length);
1510 varName = varNameExpr.substring(0, i);
1511 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
1512 break;
1513 }
1514 }
1515 }
1516 // on the first call initialize priorVariables
1517 if (priorVariables == null) {
1518 priorVariables = new ArrayList<>();
1519 priorVariables.add(builder.midString(offset, length));
1520 }
1521 // handle cyclic substitution
1522 checkCyclicSubstitution(varName, priorVariables);
1523 priorVariables.add(varName);
1524 // resolve the variable
1525 String varValue = resolveVariable(varName, builder, startPos, endPos);
1526 if (varValue == null) {
1527 varValue = varDefaultValue;
1528 }
1529 if (varValue != null) {
1530 final int varLen = varValue.length();
1531 builder.replace(startPos, endPos, varValue);
1532 altered = true;
1533 int change = 0;
1534 if (!substitutionInValuesDisabled) { // recursive replace
1535 change = substitute(builder, startPos, varLen, priorVariables).lengthChange;
1536 }
1537 change = change + varLen - (endPos - startPos);
1538 pos += change;
1539 bufEnd += change;
1540 lengthChange += change;
1541 } else if (undefinedVariableException) {
1542 throw new IllegalArgumentException(String.format("Cannot resolve variable '%s' (enableSubstitutionInVariables=%s).", varName,
1543 substitutionInVariablesEnabled));
1544 }
1545 // remove variable from the cyclic stack
1546 priorVariables.remove(priorVariables.size() - 1);
1547 break;
1548 }
1549 nestedVarCount--;
1550 pos += endMatchLen;
1551 }
1552 }
1553 }
1554 }
1555 return new Result(altered, lengthChange);
1556 }
1557
1558 /**
1559 * Returns a string representation of the object.
1560 *
1561 * @return A string representation of the object.
1562 * @since 1.11.0
1563 */
1564 @Override
1565 public String toString() {
1566 // @formatter:off
1567 return new StringBuilder()
1568 .append("StringSubstitutor [disableSubstitutionInValues=")
1569 .append(disableSubstitutionInValues)
1570 .append(", enableSubstitutionInVariables=")
1571 .append(enableSubstitutionInVariables)
1572 .append(", enableUndefinedVariableException=")
1573 .append(failOnUndefinedVariable)
1574 .append(", escapeChar=")
1575 .append(escapeChar)
1576 .append(", prefixMatcher=")
1577 .append(prefixMatcher)
1578 .append(", preserveEscapes=")
1579 .append(preserveEscapes)
1580 .append(", suffixMatcher=")
1581 .append(suffixMatcher)
1582 .append(", valueDelimiterMatcher=")
1583 .append(valueDelimiterMatcher)
1584 .append(", variableResolver=")
1585 .append(variableResolver)
1586 .append("]")
1587 .toString();
1588 // @formatter:on
1589 }
1590 }