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 // Escape
675 /**
676 * Returns the escape character.
677 *
678 * @return The character used for escaping variable references
679 */
680 public char getEscapeChar() {
681 return escapeChar;
682 }
683
684 /**
685 * Gets the StringLookup that is used to lookup variables.
686 *
687 * @return The StringLookup
688 */
689 public StringLookup getStringLookup() {
690 return variableResolver;
691 }
692
693 /**
694 * Gets the variable default value delimiter matcher currently in use.
695 * <p>
696 * The variable default value delimiter is the character or characters that delimit the variable name and the
697 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default
698 * value delimiter matches.
699 * </p>
700 * <p>
701 * If it returns null, then the variable default value resolution is disabled.
702 *
703 * @return The variable default value delimiter matcher in use, may be null
704 */
705 public StringMatcher getValueDelimiterMatcher() {
706 return valueDelimiterMatcher;
707 }
708
709 /**
710 * Gets the variable prefix matcher currently in use.
711 * <p>
712 * The variable prefix is the character or characters that identify the start of a variable. This prefix is
713 * expressed in terms of a matcher allowing advanced prefix matches.
714 * </p>
715 *
716 * @return The prefix matcher in use
717 */
718 public StringMatcher getVariablePrefixMatcher() {
719 return prefixMatcher;
720 }
721
722 /**
723 * Gets the variable suffix matcher currently in use.
724 * <p>
725 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed
726 * in terms of a matcher allowing advanced suffix matches.
727 * </p>
728 *
729 * @return The suffix matcher in use
730 */
731 public StringMatcher getVariableSuffixMatcher() {
732 return suffixMatcher;
733 }
734
735 /**
736 * Returns a flag whether substitution is disabled in variable values.If set to <strong>true</strong>, the values of variables
737 * can contain other variables will not be processed and substituted original variable is evaluated, e.g.
738 *
739 * <pre>
740 * Map<String, String> valuesMap = new HashMap<>();
741 * valuesMap.put("name", "Douglas ${surname}");
742 * valuesMap.put("surname", "Crockford");
743 * String templateString = "Hi ${name}";
744 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
745 * String resolvedString = sub.replace(templateString);
746 * </pre>
747 *
748 * yielding:
749 *
750 * <pre>
751 * Hi Douglas ${surname}
752 * </pre>
753 *
754 * @return The substitution in variable values flag
755 */
756 public boolean isDisableSubstitutionInValues() {
757 return disableSubstitutionInValues;
758 }
759
760 /**
761 * Returns a flag whether substitution is done in variable names.
762 *
763 * @return The substitution in variable names flag
764 */
765 public boolean isEnableSubstitutionInVariables() {
766 return enableSubstitutionInVariables;
767 }
768
769 /**
770 * Returns a flag whether exception can be thrown upon undefined variable.
771 *
772 * @return The fail on undefined variable flag
773 */
774 public boolean isEnableUndefinedVariableException() {
775 return failOnUndefinedVariable;
776 }
777
778 /**
779 * Returns the flag controlling whether escapes are preserved during substitution.
780 *
781 * @return The preserve escape flag
782 */
783 public boolean isPreserveEscapes() {
784 return preserveEscapes;
785 }
786
787 /**
788 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
789 * array as a template. The array is not altered by this method.
790 *
791 * @param source the character array to replace in, not altered, null returns null
792 * @return The result of the replace operation
793 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
794 */
795 public String replace(final char[] source) {
796 if (source == null) {
797 return null;
798 }
799 final TextStringBuilder buf = new TextStringBuilder(source.length).append(source);
800 substitute(buf, 0, source.length);
801 return buf.toString();
802 }
803
804 /**
805 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
806 * array as a template. The array is not altered by this method.
807 * <p>
808 * Only the specified portion of the array will be processed. The rest of the array is not processed, and is not
809 * returned.
810 * </p>
811 *
812 * @param source the character array to replace in, not altered, null returns null
813 * @param offset the start offset within the array, must be valid
814 * @param length the length within the array to be processed, must be valid
815 * @return The result of the replace operation
816 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
817 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the
818 * range {@code 0 <= offset <= chars.length}
819 * @throws StringIndexOutOfBoundsException if {@code length < 0}
820 * @throws StringIndexOutOfBoundsException if {@code offset + length > chars.length}
821 */
822 public String replace(final char[] source, final int offset, final int length) {
823 if (source == null) {
824 return null;
825 }
826 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
827 substitute(buf, 0, length);
828 return buf.toString();
829 }
830
831 /**
832 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as
833 * a template. The source is not altered by this method.
834 *
835 * @param source the buffer to use as a template, not changed, null returns null
836 * @return The result of the replace operation
837 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
838 */
839 public String replace(final CharSequence source) {
840 if (source == null) {
841 return null;
842 }
843 return replace(source, 0, source.length());
844 }
845
846 /**
847 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as
848 * a template. The source is not altered by this method.
849 * <p>
850 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not
851 * returned.
852 * </p>
853 *
854 * @param source the buffer to use as a template, not changed, null returns null
855 * @param offset the start offset within the array, must be valid
856 * @param length the length within the array to be processed, must be valid
857 * @return The result of the replace operation
858 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
859 */
860 public String replace(final CharSequence source, final int offset, final int length) {
861 if (source == null) {
862 return null;
863 }
864 final TextStringBuilder buf = new TextStringBuilder(length).append(source.toString(), offset, length);
865 substitute(buf, 0, length);
866 return buf.toString();
867 }
868
869 /**
870 * Replaces all the occurrences of variables in the given source object with their matching values from the
871 * resolver. The input source object is converted to a string using {@code toString} and is not altered.
872 *
873 * @param source the source to replace in, null returns null
874 * @return The result of the replace operation
875 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
876 */
877 public String replace(final Object source) {
878 if (source == null) {
879 return null;
880 }
881 final TextStringBuilder buf = new TextStringBuilder().append(source);
882 substitute(buf, 0, buf.length());
883 return buf.toString();
884 }
885
886 /**
887 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
888 * string as a template.
889 *
890 * @param source the string to replace in, null returns null
891 * @return The result of the replace operation
892 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
893 */
894 public String replace(final String source) {
895 if (source == null) {
896 return null;
897 }
898 final TextStringBuilder buf = new TextStringBuilder(source);
899 if (!substitute(buf, 0, source.length())) {
900 return source;
901 }
902 return buf.toString();
903 }
904
905 /**
906 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
907 * string as a template.
908 * <p>
909 * Only the specified portion of the string will be processed. The rest of the string is not processed, and is not
910 * returned.
911 * </p>
912 *
913 * @param source the string to replace in, null returns null
914 * @param offset the start offset within the source, must be valid
915 * @param length the length within the source to be processed, must be valid
916 * @return The result of the replace operation
917 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
918 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the
919 * range {@code 0 <= offset <= source.length()}
920 * @throws StringIndexOutOfBoundsException if {@code length < 0}
921 * @throws StringIndexOutOfBoundsException if {@code offset + length > source.length()}
922 */
923 public String replace(final String source, final int offset, final int length) {
924 if (source == null) {
925 return null;
926 }
927 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
928 if (!substitute(buf, 0, length)) {
929 return source.substring(offset, offset + length);
930 }
931 return buf.toString();
932 }
933
934 /**
935 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
936 * buffer as a template. The buffer is not altered by this method.
937 *
938 * @param source the buffer to use as a template, not changed, null returns null
939 * @return The result of the replace operation
940 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
941 */
942 public String replace(final StringBuffer source) {
943 if (source == null) {
944 return null;
945 }
946 final TextStringBuilder buf = new TextStringBuilder(source.length()).append(source);
947 substitute(buf, 0, buf.length());
948 return buf.toString();
949 }
950
951 /**
952 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
953 * buffer as a template. The buffer is not altered by this method.
954 * <p>
955 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not
956 * returned.
957 * </p>
958 *
959 * @param source the buffer to use as a template, not changed, null returns null
960 * @param offset the start offset within the source, must be valid
961 * @param length the length within the source to be processed, must be valid
962 * @return The result of the replace operation
963 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
964 */
965 public String replace(final StringBuffer source, final int offset, final int length) {
966 if (source == null) {
967 return null;
968 }
969 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
970 substitute(buf, 0, length);
971 return buf.toString();
972 }
973
974 /**
975 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
976 * builder as a template. The builder is not altered by this method.
977 *
978 * @param source the builder to use as a template, not changed, null returns null
979 * @return The result of the replace operation
980 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
981 */
982 public String replace(final TextStringBuilder source) {
983 if (source == null) {
984 return null;
985 }
986 final TextStringBuilder builder = new TextStringBuilder(source.length()).append(source);
987 substitute(builder, 0, builder.length());
988 return builder.toString();
989 }
990
991 /**
992 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
993 * builder as a template. The builder is not altered by this method.
994 * <p>
995 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, and is not
996 * returned.
997 * </p>
998 *
999 * @param source the builder to use as a template, not changed, null returns null
1000 * @param offset the start offset within the source, must be valid
1001 * @param length the length within the source to be processed, must be valid
1002 * @return The result of the replace operation
1003 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1004 */
1005 public String replace(final TextStringBuilder source, final int offset, final int length) {
1006 if (source == null) {
1007 return null;
1008 }
1009 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1010 substitute(buf, 0, length);
1011 return buf.toString();
1012 }
1013
1014 /**
1015 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1016 * resolver. The buffer is updated with the result.
1017 *
1018 * @param source the buffer to replace in, updated, null returns zero
1019 * @return true if altered
1020 */
1021 public boolean replaceIn(final StringBuffer source) {
1022 if (source == null) {
1023 return false;
1024 }
1025 return replaceIn(source, 0, source.length());
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 * <p>
1032 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is
1033 * not deleted.
1034 * </p>
1035 *
1036 * @param source the buffer to replace in, updated, null returns zero
1037 * @param offset the start offset within the source, must be valid
1038 * @param length the length within the source to be processed, must be valid
1039 * @return true if altered
1040 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1041 */
1042 public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
1043 if (source == null) {
1044 return false;
1045 }
1046 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1047 if (!substitute(buf, 0, length)) {
1048 return false;
1049 }
1050 source.replace(offset, offset + length, buf.toString());
1051 return true;
1052 }
1053
1054 /**
1055 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1056 * resolver. The buffer is updated with the result.
1057 *
1058 * @param source the buffer to replace in, updated, null returns zero
1059 * @return true if altered
1060 */
1061 public boolean replaceIn(final StringBuilder source) {
1062 if (source == null) {
1063 return false;
1064 }
1065 return replaceIn(source, 0, source.length());
1066 }
1067
1068 /**
1069 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1070 * resolver. The builder is updated with the result.
1071 * <p>
1072 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is
1073 * not deleted.
1074 * </p>
1075 *
1076 * @param source the buffer to replace in, updated, null returns zero
1077 * @param offset the start offset within the source, must be valid
1078 * @param length the length within the source to be processed, must be valid
1079 * @return true if altered
1080 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1081 */
1082 public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
1083 if (source == null) {
1084 return false;
1085 }
1086 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1087 if (!substitute(buf, 0, length)) {
1088 return false;
1089 }
1090 source.replace(offset, offset + length, buf.toString());
1091 return true;
1092 }
1093
1094 /**
1095 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1096 * resolver.
1097 *
1098 * @param source the builder to replace in, updated, null returns zero
1099 * @return true if altered
1100 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1101 */
1102 public boolean replaceIn(final TextStringBuilder source) {
1103 if (source == null) {
1104 return false;
1105 }
1106 return substitute(source, 0, source.length());
1107 }
1108
1109 /**
1110 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1111 * resolver.
1112 * <p>
1113 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, but it is
1114 * not deleted.
1115 * </p>
1116 *
1117 * @param source the builder to replace in, null returns zero
1118 * @param offset the start offset within the source, must be valid
1119 * @param length the length within the source to be processed, must be valid
1120 * @return true if altered
1121 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1122 */
1123 public boolean replaceIn(final TextStringBuilder source, final int offset, final int length) {
1124 if (source == null) {
1125 return false;
1126 }
1127 return substitute(source, offset, length);
1128 }
1129
1130 /**
1131 * Internal method that resolves the value of a variable.
1132 * <p>
1133 * Most users of this class do not need to call this method. This method is called automatically by the substitution
1134 * process.
1135 * </p>
1136 * <p>
1137 * Writers of subclasses can override this method if they need to alter how each substitution occurs. The method is
1138 * passed the variable's name and must return the corresponding value. This implementation uses the
1139 * {@link #getStringLookup()} with the variable's name as the key.
1140 * </p>
1141 *
1142 * @param variableName the name of the variable, not null
1143 * @param buf the buffer where the substitution is occurring, not null
1144 * @param startPos the start position of the variable including the prefix, valid
1145 * @param endPos the end position of the variable including the suffix, valid
1146 * @return The variable's value or <strong>null</strong> if the variable is unknown
1147 */
1148 protected String resolveVariable(final String variableName, final TextStringBuilder buf, final int startPos,
1149 final int endPos) {
1150 final StringLookup resolver = getStringLookup();
1151 if (resolver == null) {
1152 return null;
1153 }
1154 return resolver.apply(variableName);
1155 }
1156
1157 /**
1158 * Sets a flag whether substitution is done in variable values (recursive).
1159 *
1160 * @param disableSubstitutionInValues true if substitution in variable value are disabled
1161 * @return this, to enable chaining
1162 */
1163 public StringSubstitutor setDisableSubstitutionInValues(final boolean disableSubstitutionInValues) {
1164 this.disableSubstitutionInValues = disableSubstitutionInValues;
1165 return this;
1166 }
1167
1168 /**
1169 * Sets a flag whether substitution is done in variable names. If set to <strong>true</strong>, the names of variables can
1170 * contain other variables which are processed first before the original variable is evaluated, e.g.
1171 * {@code ${jre-${java.version}}}. The default value is <strong>false</strong>.
1172 *
1173 * @param enableSubstitutionInVariables the new value of the flag
1174 * @return this, to enable chaining
1175 */
1176 public StringSubstitutor setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) {
1177 this.enableSubstitutionInVariables = enableSubstitutionInVariables;
1178 return this;
1179 }
1180
1181 /**
1182 * Sets a flag whether exception should be thrown if any variable is undefined.
1183 *
1184 * @param failOnUndefinedVariable true if exception should be thrown on undefined variable
1185 * @return this, to enable chaining
1186 */
1187 public StringSubstitutor setEnableUndefinedVariableException(final boolean failOnUndefinedVariable) {
1188 this.failOnUndefinedVariable = failOnUndefinedVariable;
1189 return this;
1190 }
1191
1192 /**
1193 * Sets the escape character. If this character is placed before a variable reference in the source text, this
1194 * variable will be ignored.
1195 *
1196 * @param escapeChar the escape character (0 for disabling escaping)
1197 * @return this, to enable chaining
1198 */
1199 public StringSubstitutor setEscapeChar(final char escapeChar) {
1200 this.escapeChar = escapeChar;
1201 return this;
1202 }
1203
1204 /**
1205 * Sets a flag controlling whether escapes are preserved during substitution. If set to <strong>true</strong>, the escape
1206 * character is retained during substitution (e.g. {@code $${this-is-escaped}} remains {@code $${this-is-escaped}}).
1207 * If set to <strong>false</strong>, the escape character is removed during substitution (e.g. {@code $${this-is-escaped}}
1208 * becomes {@code ${this-is-escaped}}). The default value is <strong>false</strong>
1209 *
1210 * @param preserveEscapes true if escapes are to be preserved
1211 * @return this, to enable chaining
1212 */
1213 public StringSubstitutor setPreserveEscapes(final boolean preserveEscapes) {
1214 this.preserveEscapes = preserveEscapes;
1215 return this;
1216 }
1217
1218 /**
1219 * Sets the variable default value delimiter to use.
1220 * <p>
1221 * The variable default value delimiter is the character or characters that delimit the variable name and the
1222 * variable default value. This method allows a single character variable default value delimiter to be easily set.
1223 * </p>
1224 *
1225 * @param valueDelimiter the variable default value delimiter character to use
1226 * @return this, to enable chaining
1227 */
1228 public StringSubstitutor setValueDelimiter(final char valueDelimiter) {
1229 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.charMatcher(valueDelimiter));
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 string variable default value delimiter to be easily set.
1237 * </p>
1238 * <p>
1239 * If the {@code valueDelimiter} is null or empty string, then the variable default value resolution becomes
1240 * disabled.
1241 * </p>
1242 *
1243 * @param valueDelimiter the variable default value delimiter string to use, may be null or empty
1244 * @return this, to enable chaining
1245 */
1246 public StringSubstitutor setValueDelimiter(final String valueDelimiter) {
1247 if (valueDelimiter == null || valueDelimiter.isEmpty()) {
1248 setValueDelimiterMatcher(null);
1249 return this;
1250 }
1251 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.stringMatcher(valueDelimiter));
1252 }
1253
1254 /**
1255 * Sets the variable default value delimiter matcher to use.
1256 * <p>
1257 * The variable default value delimiter is the character or characters that delimit the variable name and the
1258 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default
1259 * value delimiter matches.
1260 * </p>
1261 * <p>
1262 * If the {@code valueDelimiterMatcher} is null, then the variable default value resolution becomes disabled.
1263 * </p>
1264 *
1265 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null
1266 * @return this, to enable chaining
1267 */
1268 public StringSubstitutor setValueDelimiterMatcher(final StringMatcher valueDelimiterMatcher) {
1269 this.valueDelimiterMatcher = valueDelimiterMatcher;
1270 return this;
1271 }
1272
1273 /**
1274 * Sets the variable prefix to use.
1275 * <p>
1276 * The variable prefix is the character or characters that identify the start of a variable. This method allows a
1277 * single character prefix to be easily set.
1278 * </p>
1279 *
1280 * @param prefix the prefix character to use
1281 * @return this, to enable chaining
1282 */
1283 public StringSubstitutor setVariablePrefix(final char prefix) {
1284 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.charMatcher(prefix));
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 * string prefix to be easily set.
1292 * </p>
1293 *
1294 * @param prefix the prefix for variables, not null
1295 * @return this, to enable chaining
1296 * @throws IllegalArgumentException if the prefix is null
1297 */
1298 public StringSubstitutor setVariablePrefix(final String prefix) {
1299 Validate.isTrue(prefix != null, "Variable prefix must not be null!");
1300 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(prefix));
1301 }
1302
1303 /**
1304 * Sets the variable prefix matcher currently in use.
1305 * <p>
1306 * The variable prefix is the character or characters that identify the start of a variable. This prefix is
1307 * expressed in terms of a matcher allowing advanced prefix matches.
1308 * </p>
1309 *
1310 * @param prefixMatcher the prefix matcher to use, null ignored
1311 * @return this, to enable chaining
1312 * @throws IllegalArgumentException if the prefix matcher is null
1313 */
1314 public StringSubstitutor setVariablePrefixMatcher(final StringMatcher prefixMatcher) {
1315 Validate.isTrue(prefixMatcher != null, "Variable prefix matcher must not be null!");
1316 this.prefixMatcher = prefixMatcher;
1317 return this;
1318 }
1319
1320 /**
1321 * Sets the VariableResolver that is used to lookup variables.
1322 *
1323 * @param variableResolver the VariableResolver
1324 * @return this, to enable chaining
1325 */
1326 public StringSubstitutor setVariableResolver(final StringLookup variableResolver) {
1327 this.variableResolver = variableResolver;
1328 return this;
1329 }
1330
1331 /**
1332 * Sets the variable suffix to use.
1333 * <p>
1334 * The variable suffix is the character or characters that identify the end of a variable. This method allows a
1335 * single character suffix to be easily set.
1336 * </p>
1337 *
1338 * @param suffix the suffix character to use
1339 * @return this, to enable chaining
1340 */
1341 public StringSubstitutor setVariableSuffix(final char suffix) {
1342 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.charMatcher(suffix));
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 * string suffix to be easily set.
1350 * </p>
1351 *
1352 * @param suffix the suffix for variables, not null
1353 * @return this, to enable chaining
1354 * @throws IllegalArgumentException if the suffix is null
1355 */
1356 public StringSubstitutor setVariableSuffix(final String suffix) {
1357 Validate.isTrue(suffix != null, "Variable suffix must not be null!");
1358 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(suffix));
1359 }
1360
1361 /**
1362 * Sets the variable suffix matcher currently in use.
1363 * <p>
1364 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed
1365 * in terms of a matcher allowing advanced suffix matches.
1366 * </p>
1367 *
1368 * @param suffixMatcher the suffix matcher to use, null ignored
1369 * @return this, to enable chaining
1370 * @throws IllegalArgumentException if the suffix matcher is null
1371 */
1372 public StringSubstitutor setVariableSuffixMatcher(final StringMatcher suffixMatcher) {
1373 Validate.isTrue(suffixMatcher != null, "Variable suffix matcher must not be null!");
1374 this.suffixMatcher = suffixMatcher;
1375 return this;
1376 }
1377
1378 /**
1379 * Internal method that substitutes the variables.
1380 * <p>
1381 * Most users of this class do not need to call this method. This method will be called automatically by another
1382 * (public) method.
1383 * </p>
1384 * <p>
1385 * Writers of subclasses can override this method if they need access to the substitution process at the start or
1386 * end.
1387 * </p>
1388 *
1389 * @param builder the string builder to substitute into, not null
1390 * @param offset the start offset within the builder, must be valid
1391 * @param length the length within the builder to be processed, must be valid
1392 * @return true if altered
1393 */
1394 protected boolean substitute(final TextStringBuilder builder, final int offset, final int length) {
1395 return substitute(builder, offset, length, null).altered;
1396 }
1397
1398 /**
1399 * Recursive handler for multiple levels of interpolation. This is the main interpolation method, which resolves the
1400 * values of all variable references contained in the passed in text.
1401 *
1402 * @param builder the string builder to substitute into, not null
1403 * @param offset the start offset within the builder, must be valid
1404 * @param length the length within the builder to be processed, must be valid
1405 * @param priorVariables the stack keeping track of the replaced variables, may be null
1406 * @return The result.
1407 * @throws IllegalArgumentException if variable is not found and <pre>isEnableUndefinedVariableException()==true</pre>
1408 * @since 1.9
1409 */
1410 private Result substitute(final TextStringBuilder builder, final int offset, final int length,
1411 List<String> priorVariables) {
1412 Objects.requireNonNull(builder, "builder");
1413 final StringMatcher prefixMatcher = getVariablePrefixMatcher();
1414 final StringMatcher suffixMatcher = getVariableSuffixMatcher();
1415 final char escapeCh = getEscapeChar();
1416 final StringMatcher valueDelimMatcher = getValueDelimiterMatcher();
1417 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
1418 final boolean substitutionInValuesDisabled = isDisableSubstitutionInValues();
1419 final boolean undefinedVariableException = isEnableUndefinedVariableException();
1420 final boolean preserveEscapes = isPreserveEscapes();
1421
1422 boolean altered = false;
1423 int lengthChange = 0;
1424 int bufEnd = offset + length;
1425 int pos = offset;
1426 int escPos = -1;
1427 outer: while (pos < bufEnd) {
1428 final int startMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd);
1429 if (startMatchLen == 0) {
1430 pos++;
1431 } else {
1432 // found variable start marker
1433 if (pos > offset && builder.charAt(pos - 1) == escapeCh) {
1434 // escape detected
1435 if (preserveEscapes) {
1436 // keep escape
1437 pos++;
1438 continue;
1439 }
1440 // mark esc ch for deletion if we find a complete variable
1441 escPos = pos - 1;
1442 }
1443 // find suffix
1444 int startPos = pos;
1445 pos += startMatchLen;
1446 int endMatchLen = 0;
1447 int nestedVarCount = 0;
1448 while (pos < bufEnd) {
1449 if (substitutionInVariablesEnabled && prefixMatcher.isMatch(builder, pos, offset, bufEnd) != 0) {
1450 // found a nested variable start
1451 endMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd);
1452 nestedVarCount++;
1453 pos += endMatchLen;
1454 continue;
1455 }
1456
1457 endMatchLen = suffixMatcher.isMatch(builder, pos, offset, bufEnd);
1458 if (endMatchLen == 0) {
1459 pos++;
1460 } else {
1461 // found variable end marker
1462 if (nestedVarCount == 0) {
1463 if (escPos >= 0) {
1464 // delete escape
1465 builder.deleteCharAt(escPos);
1466 escPos = -1;
1467 lengthChange--;
1468 altered = true;
1469 bufEnd--;
1470 pos = startPos + 1;
1471 startPos--;
1472 continue outer;
1473 }
1474 // get var name
1475 String varNameExpr = builder.midString(startPos + startMatchLen,
1476 pos - startPos - startMatchLen);
1477 if (substitutionInVariablesEnabled) {
1478 final TextStringBuilder bufName = new TextStringBuilder(varNameExpr);
1479 substitute(bufName, 0, bufName.length());
1480 varNameExpr = bufName.toString();
1481 }
1482 pos += endMatchLen;
1483 final int endPos = pos;
1484
1485 String varName = varNameExpr;
1486 String varDefaultValue = null;
1487
1488 if (valueDelimMatcher != null) {
1489 final char[] varNameExprChars = varNameExpr.toCharArray();
1490 int valueDelimiterMatchLen = 0;
1491 for (int i = 0; i < varNameExprChars.length; i++) {
1492 // if there's any nested variable when nested variable substitution disabled,
1493 // then stop resolving name and default value.
1494 if (!substitutionInVariablesEnabled && prefixMatcher.isMatch(varNameExprChars, i, i,
1495 varNameExprChars.length) != 0) {
1496 break;
1497 }
1498 if (valueDelimMatcher.isMatch(varNameExprChars, i, 0,
1499 varNameExprChars.length) != 0) {
1500 valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i, 0,
1501 varNameExprChars.length);
1502 varName = varNameExpr.substring(0, i);
1503 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
1504 break;
1505 }
1506 }
1507 }
1508
1509 // on the first call initialize priorVariables
1510 if (priorVariables == null) {
1511 priorVariables = new ArrayList<>();
1512 priorVariables.add(builder.midString(offset, length));
1513 }
1514
1515 // handle cyclic substitution
1516 checkCyclicSubstitution(varName, priorVariables);
1517 priorVariables.add(varName);
1518
1519 // resolve the variable
1520 String varValue = resolveVariable(varName, builder, startPos, endPos);
1521 if (varValue == null) {
1522 varValue = varDefaultValue;
1523 }
1524 if (varValue != null) {
1525 final int varLen = varValue.length();
1526 builder.replace(startPos, endPos, varValue);
1527 altered = true;
1528 int change = 0;
1529 if (!substitutionInValuesDisabled) { // recursive replace
1530 change = substitute(builder, startPos, varLen, priorVariables).lengthChange;
1531 }
1532 change = change + varLen - (endPos - startPos);
1533 pos += change;
1534 bufEnd += change;
1535 lengthChange += change;
1536 } else if (undefinedVariableException) {
1537 throw new IllegalArgumentException(
1538 String.format("Cannot resolve variable '%s' (enableSubstitutionInVariables=%s).",
1539 varName, substitutionInVariablesEnabled));
1540 }
1541
1542 // remove variable from the cyclic stack
1543 priorVariables.remove(priorVariables.size() - 1);
1544 break;
1545 }
1546 nestedVarCount--;
1547 pos += endMatchLen;
1548 }
1549 }
1550 }
1551 }
1552 return new Result(altered, lengthChange);
1553 }
1554
1555 /**
1556 * Returns a string representation of the object.
1557 *
1558 * @return a string representation of the object.
1559 * @since 1.11.0
1560 */
1561 @Override
1562 public String toString() {
1563 // @formatter:off
1564 return new StringBuilder()
1565 .append("StringSubstitutor [disableSubstitutionInValues=")
1566 .append(disableSubstitutionInValues)
1567 .append(", enableSubstitutionInVariables=")
1568 .append(enableSubstitutionInVariables)
1569 .append(", enableUndefinedVariableException=")
1570 .append(failOnUndefinedVariable)
1571 .append(", escapeChar=")
1572 .append(escapeChar)
1573 .append(", prefixMatcher=")
1574 .append(prefixMatcher)
1575 .append(", preserveEscapes=")
1576 .append(preserveEscapes)
1577 .append(", suffixMatcher=")
1578 .append(suffixMatcher)
1579 .append(", valueDelimiterMatcher=")
1580 .append(valueDelimiterMatcher)
1581 .append(", variableResolver=")
1582 .append(variableResolver)
1583 .append("]")
1584 .toString();
1585 // @formatter:on
1586 }
1587 }