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 * Returns a flag whether substitution is disabled in variable values.If set to <strong>true</strong>, the values of variables
736 * can contain other variables will not be processed and substituted original variable is evaluated, e.g.
737 *
738 * <pre>
739 * Map<String, String> valuesMap = new HashMap<>();
740 * valuesMap.put("name", "Douglas ${surname}");
741 * valuesMap.put("surname", "Crockford");
742 * String templateString = "Hi ${name}";
743 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
744 * String resolvedString = sub.replace(templateString);
745 * </pre>
746 *
747 * yielding:
748 *
749 * <pre>
750 * Hi Douglas ${surname}
751 * </pre>
752 *
753 * @return The substitution in variable values flag.
754 */
755 public boolean isDisableSubstitutionInValues() {
756 return disableSubstitutionInValues;
757 }
758
759 /**
760 * Returns a flag whether substitution is done in variable names.
761 *
762 * @return The substitution in variable names flag.
763 */
764 public boolean isEnableSubstitutionInVariables() {
765 return enableSubstitutionInVariables;
766 }
767
768 /**
769 * Returns a flag whether exception can be thrown upon undefined variable.
770 *
771 * @return The fail on undefined variable flag.
772 */
773 public boolean isEnableUndefinedVariableException() {
774 return failOnUndefinedVariable;
775 }
776
777 /**
778 * Returns the flag controlling whether escapes are preserved during substitution.
779 *
780 * @return The preserve escape flag.
781 */
782 public boolean isPreserveEscapes() {
783 return preserveEscapes;
784 }
785
786 /**
787 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
788 * array as a template. The array is not altered by this method.
789 *
790 * @param source the character array to replace in, not altered, null returns null.
791 * @return The result of the replace operation.
792 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
793 */
794 public String replace(final char[] source) {
795 if (source == null) {
796 return null;
797 }
798 final TextStringBuilder buf = new TextStringBuilder(source.length).append(source);
799 substitute(buf, 0, source.length);
800 return buf.toString();
801 }
802
803 /**
804 * 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
805 * altered by this method.
806 * <p>
807 * Only the specified portion of the array will be processed. The rest of the array is not processed, and is not returned.
808 * </p>
809 *
810 * @param source the character array to replace in, not altered, null returns null.
811 * @param offset the start offset within the array, must be valid.
812 * @param length the length within the array to be processed, must be valid.
813 * @return The result of the replace operation.
814 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
815 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the 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 string as a template.
904 * <p>
905 * Only the specified portion of the string will be processed. The rest of the string is not processed, and is not returned.
906 * </p>
907 *
908 * @param source the string to replace in, null returns null.
909 * @param offset the start offset within the source, must be valid.
910 * @param length the length within the source to be processed, must be valid.
911 * @return The result of the replace operation.
912 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
913 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the range {@code 0 <= offset <= source.length()}.
914 * @throws StringIndexOutOfBoundsException if {@code length < 0}.
915 * @throws StringIndexOutOfBoundsException if {@code offset + length > source.length()}.
916 */
917 public String replace(final String source, final int offset, final int length) {
918 if (source == null) {
919 return null;
920 }
921 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
922 if (!substitute(buf, 0, length)) {
923 return source.substring(offset, offset + length);
924 }
925 return buf.toString();
926 }
927
928 /**
929 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
930 * buffer as a template. The buffer is not altered by this method.
931 *
932 * @param source the buffer to use as a template, not changed, null returns null.
933 * @return The result of the replace operation.
934 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
935 */
936 public String replace(final StringBuffer source) {
937 if (source == null) {
938 return null;
939 }
940 final TextStringBuilder buf = new TextStringBuilder(source.length()).append(source);
941 substitute(buf, 0, buf.length());
942 return buf.toString();
943 }
944
945 /**
946 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
947 * buffer as a template. The buffer is not altered by this method.
948 * <p>
949 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not
950 * returned.
951 * </p>
952 *
953 * @param source the buffer to use as a template, not changed, null returns null.
954 * @param offset the start offset within the source, must be valid.
955 * @param length the length within the source to be processed, must be valid.
956 * @return The result of the replace operation.
957 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
958 */
959 public String replace(final StringBuffer source, final int offset, final int length) {
960 if (source == null) {
961 return null;
962 }
963 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
964 substitute(buf, 0, length);
965 return buf.toString();
966 }
967
968 /**
969 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
970 * builder as a template. The builder is not altered by this method.
971 *
972 * @param source the builder to use as a template, not changed, null returns null.
973 * @return The result of the replace operation.
974 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
975 */
976 public String replace(final TextStringBuilder source) {
977 if (source == null) {
978 return null;
979 }
980 final TextStringBuilder builder = new TextStringBuilder(source.length()).append(source);
981 substitute(builder, 0, builder.length());
982 return builder.toString();
983 }
984
985 /**
986 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
987 * builder as a template. The builder is not altered by this method.
988 * <p>
989 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, and is not
990 * returned.
991 * </p>
992 *
993 * @param source the builder to use as a template, not changed, null returns null.
994 * @param offset the start offset within the source, must be valid.
995 * @param length the length within the source to be processed, must be valid.
996 * @return The result of the replace operation.
997 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
998 */
999 public String replace(final TextStringBuilder source, final int offset, final int length) {
1000 if (source == null) {
1001 return null;
1002 }
1003 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1004 substitute(buf, 0, length);
1005 return buf.toString();
1006 }
1007
1008 /**
1009 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1010 * resolver. The buffer is updated with the result.
1011 *
1012 * @param source the buffer to replace in, updated, null returns zero.
1013 * @return true if altered
1014 */
1015 public boolean replaceIn(final StringBuffer source) {
1016 if (source == null) {
1017 return false;
1018 }
1019 return replaceIn(source, 0, source.length());
1020 }
1021
1022 /**
1023 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1024 * resolver. The buffer is updated with the result.
1025 * <p>
1026 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is
1027 * not deleted.
1028 * </p>
1029 *
1030 * @param source the buffer to replace in, updated, null returns zero.
1031 * @param offset the start offset within the source, must be valid.
1032 * @param length the length within the source to be processed, must be valid.
1033 * @return true if altered.
1034 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
1035 */
1036 public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
1037 if (source == null) {
1038 return false;
1039 }
1040 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1041 if (!substitute(buf, 0, length)) {
1042 return false;
1043 }
1044 source.replace(offset, offset + length, buf.toString());
1045 return true;
1046 }
1047
1048 /**
1049 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1050 * resolver. The buffer is updated with the result.
1051 *
1052 * @param source the buffer to replace in, updated, null returns zero.
1053 * @return true if altered.
1054 */
1055 public boolean replaceIn(final StringBuilder source) {
1056 if (source == null) {
1057 return false;
1058 }
1059 return replaceIn(source, 0, source.length());
1060 }
1061
1062 /**
1063 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1064 * resolver. The builder is updated with the result.
1065 * <p>
1066 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is
1067 * not deleted.
1068 * </p>
1069 *
1070 * @param source the buffer to replace in, updated, null returns zero.
1071 * @param offset the start offset within the source, must be valid.
1072 * @param length the length within the source to be processed, must be valid.
1073 * @return true if altered.
1074 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
1075 */
1076 public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
1077 if (source == null) {
1078 return false;
1079 }
1080 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1081 if (!substitute(buf, 0, length)) {
1082 return false;
1083 }
1084 source.replace(offset, offset + length, buf.toString());
1085 return true;
1086 }
1087
1088 /**
1089 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1090 * resolver.
1091 *
1092 * @param source the builder to replace in, updated, null returns zero.
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 TextStringBuilder source) {
1097 if (source == null) {
1098 return false;
1099 }
1100 return substitute(source, 0, source.length());
1101 }
1102
1103 /**
1104 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1105 * resolver.
1106 * <p>
1107 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, but it is
1108 * not deleted.
1109 * </p>
1110 *
1111 * @param source the builder to replace in, null returns zero.
1112 * @param offset the start offset within the source, must be valid.
1113 * @param length the length within the source to be processed, must be valid.
1114 * @return true if altered.
1115 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception.
1116 */
1117 public boolean replaceIn(final TextStringBuilder source, final int offset, final int length) {
1118 if (source == null) {
1119 return false;
1120 }
1121 return substitute(source, offset, length);
1122 }
1123
1124 /**
1125 * Internal method that resolves the value of a variable.
1126 * <p>
1127 * Most users of this class do not need to call this method. This method is called automatically by the substitution
1128 * process.
1129 * </p>
1130 * <p>
1131 * Writers of subclasses can override this method if they need to alter how each substitution occurs. The method is
1132 * passed the variable's name and must return the corresponding value. This implementation uses the
1133 * {@link #getStringLookup()} with the variable's name as the key.
1134 * </p>
1135 *
1136 * @param variableName the name of the variable, not null.
1137 * @param buf the buffer where the substitution is occurring, not null.
1138 * @param startPos the start position of the variable including the prefix, valid.
1139 * @param endPos the end position of the variable including the suffix, valid.
1140 * @return The variable's value or <strong>null</strong> if the variable is unknown.
1141 */
1142 protected String resolveVariable(final String variableName, final TextStringBuilder buf, final int startPos,
1143 final int endPos) {
1144 final StringLookup resolver = getStringLookup();
1145 if (resolver == null) {
1146 return null;
1147 }
1148 return resolver.apply(variableName);
1149 }
1150
1151 /**
1152 * Sets a flag whether substitution is done in variable values (recursive).
1153 *
1154 * @param disableSubstitutionInValues true if substitution in variable value are disabled.
1155 * @return {@code this} instance.
1156 */
1157 public StringSubstitutor setDisableSubstitutionInValues(final boolean disableSubstitutionInValues) {
1158 this.disableSubstitutionInValues = disableSubstitutionInValues;
1159 return this;
1160 }
1161
1162 /**
1163 * Sets a flag whether substitution is done in variable names. If set to <strong>true</strong>, the names of variables can
1164 * contain other variables which are processed first before the original variable is evaluated, e.g.
1165 * {@code ${jre-${java.version}}}. The default value is <strong>false</strong>.
1166 *
1167 * @param enableSubstitutionInVariables the new value of the flag.
1168 * @return {@code this} instance.
1169 */
1170 public StringSubstitutor setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) {
1171 this.enableSubstitutionInVariables = enableSubstitutionInVariables;
1172 return this;
1173 }
1174
1175 /**
1176 * Sets a flag whether exception should be thrown if any variable is undefined.
1177 *
1178 * @param failOnUndefinedVariable true if exception should be thrown on undefined variable.
1179 * @return {@code this} instance.
1180 */
1181 public StringSubstitutor setEnableUndefinedVariableException(final boolean failOnUndefinedVariable) {
1182 this.failOnUndefinedVariable = failOnUndefinedVariable;
1183 return this;
1184 }
1185
1186 /**
1187 * Sets the escape character. If this character is placed before a variable reference in the source text, this
1188 * variable will be ignored.
1189 *
1190 * @param escapeChar the escape character (0 for disabling escaping).
1191 * @return {@code this} instance.
1192 */
1193 public StringSubstitutor setEscapeChar(final char escapeChar) {
1194 this.escapeChar = escapeChar;
1195 return this;
1196 }
1197
1198 /**
1199 * Sets a flag controlling whether escapes are preserved during substitution. If set to <strong>true</strong>, the escape
1200 * character is retained during substitution (e.g. {@code $${this-is-escaped}} remains {@code $${this-is-escaped}}).
1201 * If set to <strong>false</strong>, the escape character is removed during substitution (e.g. {@code $${this-is-escaped}}
1202 * becomes {@code ${this-is-escaped}}). The default value is <strong>false</strong>
1203 *
1204 * @param preserveEscapes true if escapes are to be preserved.
1205 * @return {@code this} instance.
1206 */
1207 public StringSubstitutor setPreserveEscapes(final boolean preserveEscapes) {
1208 this.preserveEscapes = preserveEscapes;
1209 return this;
1210 }
1211
1212 /**
1213 * Sets the variable default value delimiter to use.
1214 * <p>
1215 * The variable default value delimiter is the character or characters that delimit the variable name and the
1216 * variable default value. This method allows a single character variable default value delimiter to be easily set.
1217 * </p>
1218 *
1219 * @param valueDelimiter the variable default value delimiter character to use.
1220 * @return {@code this} instance.
1221 */
1222 public StringSubstitutor setValueDelimiter(final char valueDelimiter) {
1223 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.charMatcher(valueDelimiter));
1224 }
1225
1226 /**
1227 * Sets the variable default value delimiter to use.
1228 * <p>
1229 * The variable default value delimiter is the character or characters that delimit the variable name and the
1230 * variable default value. This method allows a string variable default value delimiter to be easily set.
1231 * </p>
1232 * <p>
1233 * If the {@code valueDelimiter} is null or empty string, then the variable default value resolution becomes
1234 * disabled.
1235 * </p>
1236 *
1237 * @param valueDelimiter the variable default value delimiter string to use, may be null or empty.
1238 * @return {@code this} instance.
1239 */
1240 public StringSubstitutor setValueDelimiter(final String valueDelimiter) {
1241 if (valueDelimiter == null || valueDelimiter.isEmpty()) {
1242 setValueDelimiterMatcher(null);
1243 return this;
1244 }
1245 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.stringMatcher(valueDelimiter));
1246 }
1247
1248 /**
1249 * Sets the variable default value delimiter matcher to use.
1250 * <p>
1251 * The variable default value delimiter is the character or characters that delimit the variable name and the
1252 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default
1253 * value delimiter matches.
1254 * </p>
1255 * <p>
1256 * If the {@code valueDelimiterMatcher} is null, then the variable default value resolution becomes disabled.
1257 * </p>
1258 *
1259 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null.
1260 * @return {@code this} instance.
1261 */
1262 public StringSubstitutor setValueDelimiterMatcher(final StringMatcher valueDelimiterMatcher) {
1263 this.valueDelimiterMatcher = valueDelimiterMatcher;
1264 return this;
1265 }
1266
1267 /**
1268 * Sets the variable prefix to use.
1269 * <p>
1270 * The variable prefix is the character or characters that identify the start of a variable. This method allows a
1271 * single character prefix to be easily set.
1272 * </p>
1273 *
1274 * @param prefix the prefix character to use.
1275 * @return {@code this} instance.
1276 */
1277 public StringSubstitutor setVariablePrefix(final char prefix) {
1278 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.charMatcher(prefix));
1279 }
1280
1281 /**
1282 * Sets the variable prefix to use.
1283 * <p>
1284 * The variable prefix is the character or characters that identify the start of a variable. This method allows a
1285 * string prefix to be easily set.
1286 * </p>
1287 *
1288 * @param prefix the prefix for variables, not null.
1289 * @return {@code this} instance.
1290 * @throws IllegalArgumentException if the prefix is null.
1291 */
1292 public StringSubstitutor setVariablePrefix(final String prefix) {
1293 Validate.isTrue(prefix != null, "Variable prefix must not be null!");
1294 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(prefix));
1295 }
1296
1297 /**
1298 * Sets the variable prefix matcher currently in use.
1299 * <p>
1300 * The variable prefix is the character or characters that identify the start of a variable. This prefix is
1301 * expressed in terms of a matcher allowing advanced prefix matches.
1302 * </p>
1303 *
1304 * @param prefixMatcher the prefix matcher to use, null ignored.
1305 * @return {@code this} instance.
1306 * @throws IllegalArgumentException if the prefix matcher is null.
1307 */
1308 public StringSubstitutor setVariablePrefixMatcher(final StringMatcher prefixMatcher) {
1309 Validate.isTrue(prefixMatcher != null, "Variable prefix matcher must not be null!");
1310 this.prefixMatcher = prefixMatcher;
1311 return this;
1312 }
1313
1314 /**
1315 * Sets the VariableResolver that is used to lookup variables.
1316 *
1317 * @param variableResolver the VariableResolver.
1318 * @return {@code this} instance.
1319 */
1320 public StringSubstitutor setVariableResolver(final StringLookup variableResolver) {
1321 this.variableResolver = variableResolver;
1322 return this;
1323 }
1324
1325 /**
1326 * Sets the variable suffix to use.
1327 * <p>
1328 * The variable suffix is the character or characters that identify the end of a variable. This method allows a
1329 * single character suffix to be easily set.
1330 * </p>
1331 *
1332 * @param suffix the suffix character to use.
1333 * @return {@code this} instance.
1334 */
1335 public StringSubstitutor setVariableSuffix(final char suffix) {
1336 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.charMatcher(suffix));
1337 }
1338
1339 /**
1340 * Sets the variable suffix to use.
1341 * <p>
1342 * The variable suffix is the character or characters that identify the end of a variable. This method allows a
1343 * string suffix to be easily set.
1344 * </p>
1345 *
1346 * @param suffix the suffix for variables, not null.
1347 * @return {@code this} instance.
1348 * @throws IllegalArgumentException if the suffix is null.
1349 */
1350 public StringSubstitutor setVariableSuffix(final String suffix) {
1351 Validate.isTrue(suffix != null, "Variable suffix must not be null!");
1352 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(suffix));
1353 }
1354
1355 /**
1356 * Sets the variable suffix matcher currently in use.
1357 * <p>
1358 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed
1359 * in terms of a matcher allowing advanced suffix matches.
1360 * </p>
1361 *
1362 * @param suffixMatcher the suffix matcher to use, null ignored.
1363 * @return {@code this} instance.
1364 * @throws IllegalArgumentException if the suffix matcher is null.
1365 */
1366 public StringSubstitutor setVariableSuffixMatcher(final StringMatcher suffixMatcher) {
1367 Validate.isTrue(suffixMatcher != null, "Variable suffix matcher must not be null!");
1368 this.suffixMatcher = suffixMatcher;
1369 return this;
1370 }
1371
1372 /**
1373 * Internal method that substitutes the variables.
1374 * <p>
1375 * Most users of this class do not need to call this method. This method will be called automatically by another
1376 * (public) method.
1377 * </p>
1378 * <p>
1379 * Writers of subclasses can override this method if they need access to the substitution process at the start or
1380 * end.
1381 * </p>
1382 *
1383 * @param builder the string builder to substitute into, not null.
1384 * @param offset the start offset within the builder, must be valid.
1385 * @param length the length within the builder to be processed, must be valid.
1386 * @return true if altered.
1387 */
1388 protected boolean substitute(final TextStringBuilder builder, final int offset, final int length) {
1389 return substitute(builder, offset, length, null).altered;
1390 }
1391
1392 /**
1393 * Recursive handler for multiple levels of interpolation. This is the main interpolation method, which resolves the
1394 * values of all variable references contained in the passed in text.
1395 *
1396 * @param builder the string builder to substitute into, not null.
1397 * @param offset the start offset within the builder, must be valid.
1398 * @param length the length within the builder to be processed, must be valid.
1399 * @param priorVariables the stack keeping track of the replaced variables, may be null.
1400 * @return The result.
1401 * @throws IllegalArgumentException if variable is not found and <code>isEnableUndefinedVariableException() == true</code>.
1402 * @since 1.9
1403 */
1404 private Result substitute(final TextStringBuilder builder, final int offset, final int length,
1405 List<String> priorVariables) {
1406 Objects.requireNonNull(builder, "builder");
1407 final StringMatcher prefixMatcher = getVariablePrefixMatcher();
1408 final StringMatcher suffixMatcher = getVariableSuffixMatcher();
1409 final char escapeCh = getEscapeChar();
1410 final StringMatcher valueDelimMatcher = getValueDelimiterMatcher();
1411 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
1412 final boolean substitutionInValuesDisabled = isDisableSubstitutionInValues();
1413 final boolean undefinedVariableException = isEnableUndefinedVariableException();
1414 final boolean preserveEscapes = isPreserveEscapes();
1415
1416 boolean altered = false;
1417 int lengthChange = 0;
1418 int bufEnd = offset + length;
1419 int pos = offset;
1420 int escPos = -1;
1421 outer: while (pos < bufEnd) {
1422 final int startMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd);
1423 if (startMatchLen == 0) {
1424 pos++;
1425 } else {
1426 // found variable start marker
1427 if (pos > offset && builder.charAt(pos - 1) == escapeCh) {
1428 // escape detected
1429 if (preserveEscapes) {
1430 // keep escape
1431 pos++;
1432 continue;
1433 }
1434 // mark esc ch for deletion if we find a complete variable
1435 escPos = pos - 1;
1436 }
1437 // find suffix
1438 int startPos = pos;
1439 pos += startMatchLen;
1440 int endMatchLen = 0;
1441 int nestedVarCount = 0;
1442 while (pos < bufEnd) {
1443 if (substitutionInVariablesEnabled && prefixMatcher.isMatch(builder, pos, offset, bufEnd) != 0) {
1444 // found a nested variable start
1445 endMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd);
1446 nestedVarCount++;
1447 pos += endMatchLen;
1448 continue;
1449 }
1450
1451 endMatchLen = suffixMatcher.isMatch(builder, pos, offset, bufEnd);
1452 if (endMatchLen == 0) {
1453 pos++;
1454 } else {
1455 // found variable end marker
1456 if (nestedVarCount == 0) {
1457 if (escPos >= 0) {
1458 // delete escape
1459 builder.deleteCharAt(escPos);
1460 escPos = -1;
1461 lengthChange--;
1462 altered = true;
1463 bufEnd--;
1464 pos = startPos + 1;
1465 startPos--;
1466 continue outer;
1467 }
1468 // get var name
1469 String varNameExpr = builder.midString(startPos + startMatchLen,
1470 pos - startPos - startMatchLen);
1471 if (substitutionInVariablesEnabled) {
1472 final TextStringBuilder bufName = new TextStringBuilder(varNameExpr);
1473 substitute(bufName, 0, bufName.length());
1474 varNameExpr = bufName.toString();
1475 }
1476 pos += endMatchLen;
1477 final int endPos = pos;
1478
1479 String varName = varNameExpr;
1480 String varDefaultValue = null;
1481
1482 if (valueDelimMatcher != null) {
1483 final char[] varNameExprChars = varNameExpr.toCharArray();
1484 int valueDelimiterMatchLen = 0;
1485 for (int i = 0; i < varNameExprChars.length; i++) {
1486 // if there's any nested variable when nested variable substitution disabled,
1487 // then stop resolving name and default value.
1488 if (!substitutionInVariablesEnabled && prefixMatcher.isMatch(varNameExprChars, i, i,
1489 varNameExprChars.length) != 0) {
1490 break;
1491 }
1492 if (valueDelimMatcher.isMatch(varNameExprChars, i, 0,
1493 varNameExprChars.length) != 0) {
1494 valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i, 0,
1495 varNameExprChars.length);
1496 varName = varNameExpr.substring(0, i);
1497 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
1498 break;
1499 }
1500 }
1501 }
1502
1503 // on the first call initialize priorVariables
1504 if (priorVariables == null) {
1505 priorVariables = new ArrayList<>();
1506 priorVariables.add(builder.midString(offset, length));
1507 }
1508
1509 // handle cyclic substitution
1510 checkCyclicSubstitution(varName, priorVariables);
1511 priorVariables.add(varName);
1512
1513 // resolve the variable
1514 String varValue = resolveVariable(varName, builder, startPos, endPos);
1515 if (varValue == null) {
1516 varValue = varDefaultValue;
1517 }
1518 if (varValue != null) {
1519 final int varLen = varValue.length();
1520 builder.replace(startPos, endPos, varValue);
1521 altered = true;
1522 int change = 0;
1523 if (!substitutionInValuesDisabled) { // recursive replace
1524 change = substitute(builder, startPos, varLen, priorVariables).lengthChange;
1525 }
1526 change = change + varLen - (endPos - startPos);
1527 pos += change;
1528 bufEnd += change;
1529 lengthChange += change;
1530 } else if (undefinedVariableException) {
1531 throw new IllegalArgumentException(
1532 String.format("Cannot resolve variable '%s' (enableSubstitutionInVariables=%s).",
1533 varName, substitutionInVariablesEnabled));
1534 }
1535
1536 // remove variable from the cyclic stack
1537 priorVariables.remove(priorVariables.size() - 1);
1538 break;
1539 }
1540 nestedVarCount--;
1541 pos += endMatchLen;
1542 }
1543 }
1544 }
1545 }
1546 return new Result(altered, lengthChange);
1547 }
1548
1549 /**
1550 * Returns a string representation of the object.
1551 *
1552 * @return a string representation of the object.
1553 * @since 1.11.0
1554 */
1555 @Override
1556 public String toString() {
1557 // @formatter:off
1558 return new StringBuilder()
1559 .append("StringSubstitutor [disableSubstitutionInValues=")
1560 .append(disableSubstitutionInValues)
1561 .append(", enableSubstitutionInVariables=")
1562 .append(enableSubstitutionInVariables)
1563 .append(", enableUndefinedVariableException=")
1564 .append(failOnUndefinedVariable)
1565 .append(", escapeChar=")
1566 .append(escapeChar)
1567 .append(", prefixMatcher=")
1568 .append(prefixMatcher)
1569 .append(", preserveEscapes=")
1570 .append(preserveEscapes)
1571 .append(", suffixMatcher=")
1572 .append(suffixMatcher)
1573 .append(", valueDelimiterMatcher=")
1574 .append(valueDelimiterMatcher)
1575 .append(", variableResolver=")
1576 .append(variableResolver)
1577 .append("]")
1578 .toString();
1579 // @formatter:on
1580 }
1581 }