1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.text;
18
19 import java.util.ArrayList;
20 import java.util.List;
21 import java.util.Map;
22 import java.util.Objects;
23 import java.util.Properties;
24 import java.util.function.Function;
25 import java.util.stream.Collectors;
26
27 import org.apache.commons.lang3.Validate;
28 import org.apache.commons.text.lookup.StringLookup;
29 import org.apache.commons.text.lookup.StringLookupFactory;
30 import org.apache.commons.text.matcher.StringMatcher;
31 import org.apache.commons.text.matcher.StringMatcherFactory;
32
33 /**
34 * Substitutes variables within a string by values.
35 * <p>
36 * This class takes a piece of text and substitutes all the variables within it. The default definition of a variable is
37 * {@code ${variableName}}. The prefix and suffix can be changed via constructors and set methods.
38 * </p>
39 * <p>
40 * Variable values are typically resolved from a map, but could also be resolved from system properties, or by supplying
41 * a custom variable resolver.
42 * </p>
43 * <h2>Using System Properties</h2>
44 * <p>
45 * The simplest example is to use this class to replace Java System properties. For example:
46 * </p>
47 *
48 * <pre>
49 * StringSubstitutor
50 * .replaceSystemProperties("You are running with java.version = ${java.version} and os.name = ${os.name}.");
51 * </pre>
52 *
53 * <h2>Using a Custom Map</h2>
54 * <p>
55 * Typical usage of this class follows the following pattern:
56 * </p>
57 * <ul>
58 * <li>Create and initialize a StringSubstitutor with the map that contains the values for the variables you want to
59 * make available.</li>
60 * <li>Optionally set attributes like variable prefix, variable suffix, default value delimiter, and so on.</li>
61 * <li>Call the {@code replace()} method with in the source text for interpolation.</li>
62 * <li>The returned text contains all variable references (as long as their values are known) as resolved.</li>
63 * </ul>
64 * <p>
65 * For example:
66 * </p>
67 *
68 * <pre>
69 * // Build map
70 * Map<String, String> valuesMap = new HashMap<>();
71 * valuesMap.put("animal", "quick brown fox");
72 * valuesMap.put("target", "lazy dog");
73 * String templateString = "The ${animal} jumped over the ${target}.";
74 *
75 * // Build StringSubstitutor
76 * StringSubstitutor sub = new StringSubstitutor(valuesMap);
77 *
78 * // Replace
79 * String resolvedString = sub.replace(templateString);
80 * </pre>
81 *
82 * <p>
83 * yielding:
84 * </p>
85 *
86 * <pre>
87 * "The quick brown fox jumped over the lazy dog."
88 * </pre>
89 *
90 * <h2>Providing Default Values</h2>
91 * <p>
92 * You can set a default value for unresolved variables. The default value for a variable can be appended to the
93 * variable name after the variable default value delimiter. The default value of the variable default value delimiter
94 * is ":-", as in bash and other *nix shells.
95 * </p>
96 * <p>
97 * You can set the variable value delimiter with {@link #setValueDelimiterMatcher(StringMatcher)},
98 * {@link #setValueDelimiter(char)} or {@link #setValueDelimiter(String)}.
99 * </p>
100 * <p>
101 * For example:
102 * </p>
103 *
104 * <pre>
105 * // Build map
106 * Map<String, String> valuesMap = new HashMap<>();
107 * valuesMap.put("animal", "quick brown fox");
108 * valuesMap.put("target", "lazy dog");
109 * String templateString = "The ${animal} jumped over the ${target} ${undefined.number:-1234567890} times.";
110 *
111 * // Build StringSubstitutor
112 * StringSubstitutor sub = new StringSubstitutor(valuesMap);
113 *
114 * // Replace
115 * String resolvedString = sub.replace(templateString);
116 * </pre>
117 *
118 * <p>
119 * yielding:
120 * </p>
121 *
122 * <pre>
123 * "The quick brown fox jumped over the lazy dog 1234567890 times."
124 * </pre>
125 *
126 * <p>
127 * {@code StringSubstitutor} supports throwing exceptions for unresolved variables, you enable this by setting calling
128 * {@link #setEnableUndefinedVariableException(boolean)} with {@code true}.
129 * </p>
130 *
131 * <h2>Reusing Instances</h2>
132 * <p>
133 * Static shortcut methods cover the most common use cases. If multiple replace operations are to be performed, creating
134 * and reusing an instance of this class will be more efficient.
135 * </p>
136 *
137 * <h2>Using Interpolation</h2>
138 * <p>
139 * The default interpolator lets you use string lookups like:
140 * </p>
141 *
142 * <pre>
143 * final StringSubstitutor interpolator = StringSubstitutor.createInterpolator();
144 * final String text = interpolator.replace(
145 * "Base64 Decoder: ${base64Decoder:SGVsbG9Xb3JsZCE=}\n"
146 * + "Base64 Encoder: ${base64Encoder:HelloWorld!}\n"
147 * + "Java Constant: ${const:java.awt.event.KeyEvent.VK_ESCAPE}\n"
148 * + "Date: ${date:yyyy-MM-dd}\n"
149 * + "Environment Variable: ${env:USERNAME}\n"
150 * + "File Content: ${file:UTF-8:src/test/resources/document.properties}\n"
151 * + "Java: ${java:version}\n"
152 * + "Localhost: ${localhost:canonical-name}\n"
153 * + "Properties File: ${properties:src/test/resources/document.properties::mykey}\n"
154 * + "Resource Bundle: ${resourceBundle:org.apache.commons.text.example.testResourceBundleLookup:mykey}\n"
155 * + "System Property: ${sys:user.dir}\n"
156 * + "URL Decoder: ${urlDecoder:Hello%20World%21}\n"
157 * + "URL Encoder: ${urlEncoder:Hello World!}\n"
158 * + "XML XPath: ${xml:src/test/resources/document.xml:/root/path/to/node}\n");
159 * </pre>
160 * <p>
161 * For documentation and a full list of available lookups, see {@link StringLookupFactory}.
162 * </p>
163 * <p><strong>NOTE:</strong> The list of lookups available by default in {@link #createInterpolator()} changed
164 * in version {@code 1.10.0}. See the {@link StringLookupFactory} documentation for details and an explanation
165 * on how to reproduce the previous functionality.
166 * </p>
167 *
168 * <h2>Using Recursive Variable Replacement</h2>
169 * <p>
170 * Variable replacement can work recursively by calling {@link #setEnableSubstitutionInVariables(boolean)} with
171 * {@code true}. If a variable value contains a variable then that variable will also be replaced. Cyclic replacements
172 * are detected and will throw an exception.
173 * </p>
174 * <p>
175 * You can get the replace result to contain a variable prefix. For example:
176 * </p>
177 *
178 * <pre>
179 * "The variable ${${name}} must be used."
180 * </pre>
181 *
182 * <p>
183 * If the value of the "name" variable is "x", then only the variable "name" is replaced resulting in:
184 * </p>
185 *
186 * <pre>
187 * "The variable ${x} must be used."
188 * </pre>
189 *
190 * <p>
191 * To achieve this effect there are two possibilities: Either set a different prefix and suffix for variables which do
192 * not conflict with the result text you want to produce. The other possibility is to use the escape character, by
193 * default '$'. If this character is placed before a variable reference, this reference is ignored and won't be
194 * replaced. For example:
195 * </p>
196 *
197 * <pre>
198 * "The variable $${${name}} must be used."
199 * </pre>
200 * <p>
201 * In some complex scenarios you might even want to perform substitution in the names of variables, for instance
202 * </p>
203 *
204 * <pre>
205 * ${jre-${java.specification.version}}
206 * </pre>
207 *
208 * <p>
209 * {@code StringSubstitutor} supports this recursive substitution in variable names, but it has to be enabled explicitly
210 * by calling {@link #setEnableSubstitutionInVariables(boolean)} with {@code true}.
211 * </p>
212 *
213 * <h2>Thread Safety</h2>
214 * <p>
215 * This class is <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 StringSubstitutor.replace(source,
438 valueProperties.stringPropertyNames().stream().collect(Collectors.toMap(Function.identity(), valueProperties::getProperty)));
439 }
440
441 /**
442 * Replaces all the occurrences of variables in the given source object with their matching values from the system
443 * properties.
444 *
445 * @param source the source text containing the variables to substitute, null returns null
446 * @return The result of the replace operation
447 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
448 */
449 public static String replaceSystemProperties(final Object source) {
450 return new StringSubstitutor(StringLookupFactory.INSTANCE.systemPropertyStringLookup()).replace(source);
451 }
452
453 /**
454 * The flag whether substitution in variable values is disabled.
455 */
456 private boolean disableSubstitutionInValues;
457
458 /**
459 * The flag whether substitution in variable names is enabled.
460 */
461 private boolean enableSubstitutionInVariables;
462
463 /**
464 * The flag whether exception should be thrown on undefined variable.
465 */
466 private boolean failOnUndefinedVariable;
467
468 /**
469 * Stores the escape character.
470 */
471 private char escapeChar;
472
473 /**
474 * Stores the variable prefix.
475 */
476 private StringMatcher prefixMatcher;
477
478 /**
479 * Whether escapes should be preserved. Default is false;
480 */
481 private boolean preserveEscapes;
482
483 /**
484 * Stores the variable suffix.
485 */
486 private StringMatcher suffixMatcher;
487
488 /**
489 * Stores the default variable value delimiter.
490 */
491 private StringMatcher valueDelimiterMatcher;
492
493 /**
494 * Variable resolution is delegated to an implementor of {@link StringLookup}.
495 */
496 private StringLookup variableResolver;
497
498 /**
499 * Constructs a new instance with defaults for variable prefix and suffix and the escaping character.
500 */
501 public StringSubstitutor() {
502 this(null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
503 }
504
505 /**
506 * Constructs a new initialized instance. Uses defaults for variable prefix and suffix and the escaping
507 * character.
508 *
509 * @param <V> the type of the values in the map
510 * @param valueMap the map with the variables' values, may be null
511 */
512 public <V> StringSubstitutor(final Map<String, V> valueMap) {
513 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
514 }
515
516 /**
517 * Constructs a new initialized instance. Uses a default escaping character.
518 *
519 * @param <V> the type of the values in the map
520 * @param valueMap the map with the variables' values, may be null
521 * @param prefix the prefix for variables, not null
522 * @param suffix the suffix for variables, not null
523 * @throws IllegalArgumentException if the prefix or suffix is null
524 */
525 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix) {
526 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE);
527 }
528
529 /**
530 * Constructs a new initialized instance.
531 *
532 * @param <V> the type of the values in the map
533 * @param valueMap the map with the variables' values, may be null
534 * @param prefix the prefix for variables, not null
535 * @param suffix the suffix for variables, not null
536 * @param escape the escape character
537 * @throws IllegalArgumentException if the prefix or suffix is null
538 */
539 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
540 final char escape) {
541 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, escape);
542 }
543
544 /**
545 * Constructs a new initialized instance.
546 *
547 * @param <V> the type of the values in the map
548 * @param valueMap the map with the variables' values, may be null
549 * @param prefix the prefix for variables, not null
550 * @param suffix the suffix for variables, not null
551 * @param escape the escape character
552 * @param valueDelimiter the variable default value delimiter, may be null
553 * @throws IllegalArgumentException if the prefix or suffix is null
554 */
555 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
556 final char escape, final String valueDelimiter) {
557 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, escape, valueDelimiter);
558 }
559
560 /**
561 * Constructs a new initialized instance.
562 *
563 * @param variableResolver the variable resolver, may be null
564 */
565 public StringSubstitutor(final StringLookup variableResolver) {
566 this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
567 }
568
569 /**
570 * Constructs a new initialized instance.
571 *
572 * @param variableResolver the variable resolver, may be null
573 * @param prefix the prefix for variables, not null
574 * @param suffix the suffix for variables, not null
575 * @param escape the escape character
576 * @throws IllegalArgumentException if the prefix or suffix is null
577 */
578 public StringSubstitutor(final StringLookup variableResolver, final String prefix, final String suffix,
579 final char escape) {
580 setVariableResolver(variableResolver);
581 setVariablePrefix(prefix);
582 setVariableSuffix(suffix);
583 setEscapeChar(escape);
584 setValueDelimiterMatcher(DEFAULT_VALUE_DELIMITER);
585 }
586
587 /**
588 * Constructs a new initialized instance.
589 *
590 * @param variableResolver the variable resolver, may be null
591 * @param prefix the prefix for variables, not null
592 * @param suffix the suffix for variables, not null
593 * @param escape the escape character
594 * @param valueDelimiter the variable default value delimiter string, may be null
595 * @throws IllegalArgumentException if the prefix or suffix is null
596 */
597 public StringSubstitutor(final StringLookup variableResolver, final String prefix, final String suffix,
598 final char escape, final String valueDelimiter) {
599 setVariableResolver(variableResolver);
600 setVariablePrefix(prefix);
601 setVariableSuffix(suffix);
602 setEscapeChar(escape);
603 setValueDelimiter(valueDelimiter);
604 }
605
606 /**
607 * Constructs a new initialized instance.
608 *
609 * @param variableResolver the variable resolver, may be null
610 * @param prefixMatcher the prefix for variables, not null
611 * @param suffixMatcher the suffix for variables, not null
612 * @param escape the escape character
613 * @throws IllegalArgumentException if the prefix or suffix is null
614 */
615 public StringSubstitutor(final StringLookup variableResolver, final StringMatcher prefixMatcher,
616 final StringMatcher suffixMatcher, final char escape) {
617 this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER);
618 }
619
620 /**
621 * Constructs a new initialized instance.
622 *
623 * @param variableResolver the variable resolver, may be null
624 * @param prefixMatcher the prefix for variables, not null
625 * @param suffixMatcher the suffix for variables, not null
626 * @param escape the escape character
627 * @param valueDelimiterMatcher the variable default value delimiter matcher, may be null
628 * @throws IllegalArgumentException if the prefix or suffix is null
629 */
630 public StringSubstitutor(final StringLookup variableResolver, final StringMatcher prefixMatcher,
631 final StringMatcher suffixMatcher, final char escape, final StringMatcher valueDelimiterMatcher) {
632 setVariableResolver(variableResolver);
633 setVariablePrefixMatcher(prefixMatcher);
634 setVariableSuffixMatcher(suffixMatcher);
635 setEscapeChar(escape);
636 setValueDelimiterMatcher(valueDelimiterMatcher);
637 }
638
639 /**
640 * Creates a new instance based on the given StringSubstitutor.
641 *
642 * @param other The StringSubstitutor used as the source.
643 * @since 1.9
644 */
645 public StringSubstitutor(final StringSubstitutor other) {
646 disableSubstitutionInValues = other.isDisableSubstitutionInValues();
647 enableSubstitutionInVariables = other.isEnableSubstitutionInVariables();
648 failOnUndefinedVariable = other.isEnableUndefinedVariableException();
649 escapeChar = other.getEscapeChar();
650 prefixMatcher = other.getVariablePrefixMatcher();
651 preserveEscapes = other.isPreserveEscapes();
652 suffixMatcher = other.getVariableSuffixMatcher();
653 valueDelimiterMatcher = other.getValueDelimiterMatcher();
654 variableResolver = other.getStringLookup();
655 }
656
657 /**
658 * Checks if the specified variable is already in the stack (list) of variables.
659 *
660 * @param varName the variable name to check
661 * @param priorVariables the list of prior variables
662 */
663 private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) {
664 if (!priorVariables.contains(varName)) {
665 return;
666 }
667 final TextStringBuilder buf = new TextStringBuilder(256);
668 buf.append("Infinite loop in property interpolation of ");
669 buf.append(priorVariables.remove(0));
670 buf.append(": ");
671 buf.appendWithSeparators(priorVariables, "->");
672 throw new IllegalStateException(buf.toString());
673 }
674
675 // Escape
676 /**
677 * Returns the escape character.
678 *
679 * @return The character used for escaping variable references
680 */
681 public char getEscapeChar() {
682 return escapeChar;
683 }
684
685 /**
686 * Gets the StringLookup that is used to lookup variables.
687 *
688 * @return The StringLookup
689 */
690 public StringLookup getStringLookup() {
691 return variableResolver;
692 }
693
694 /**
695 * Gets the variable default value delimiter matcher currently in use.
696 * <p>
697 * The variable default value delimiter is the character or characters that delimit the variable name and the
698 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default
699 * value delimiter matches.
700 * </p>
701 * <p>
702 * If it returns null, then the variable default value resolution is disabled.
703 *
704 * @return The variable default value delimiter matcher in use, may be null
705 */
706 public StringMatcher getValueDelimiterMatcher() {
707 return valueDelimiterMatcher;
708 }
709
710 /**
711 * Gets the variable prefix matcher currently in use.
712 * <p>
713 * The variable prefix is the character or characters that identify the start of a variable. This prefix is
714 * expressed in terms of a matcher allowing advanced prefix matches.
715 * </p>
716 *
717 * @return The prefix matcher in use
718 */
719 public StringMatcher getVariablePrefixMatcher() {
720 return prefixMatcher;
721 }
722
723 /**
724 * Gets the variable suffix matcher currently in use.
725 * <p>
726 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed
727 * in terms of a matcher allowing advanced suffix matches.
728 * </p>
729 *
730 * @return The suffix matcher in use
731 */
732 public StringMatcher getVariableSuffixMatcher() {
733 return suffixMatcher;
734 }
735
736 /**
737 * Returns a flag whether substitution is disabled in variable values.If set to <strong>true</strong>, the values of variables
738 * can contain other variables will not be processed and substituted original variable is evaluated, e.g.
739 *
740 * <pre>
741 * Map<String, String> valuesMap = new HashMap<>();
742 * valuesMap.put("name", "Douglas ${surname}");
743 * valuesMap.put("surname", "Crockford");
744 * String templateString = "Hi ${name}";
745 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
746 * String resolvedString = sub.replace(templateString);
747 * </pre>
748 *
749 * yielding:
750 *
751 * <pre>
752 * Hi Douglas ${surname}
753 * </pre>
754 *
755 * @return The substitution in variable values flag
756 */
757 public boolean isDisableSubstitutionInValues() {
758 return disableSubstitutionInValues;
759 }
760
761 /**
762 * Returns a flag whether substitution is done in variable names.
763 *
764 * @return The substitution in variable names flag
765 */
766 public boolean isEnableSubstitutionInVariables() {
767 return enableSubstitutionInVariables;
768 }
769
770 /**
771 * Returns a flag whether exception can be thrown upon undefined variable.
772 *
773 * @return The fail on undefined variable flag
774 */
775 public boolean isEnableUndefinedVariableException() {
776 return failOnUndefinedVariable;
777 }
778
779 /**
780 * Returns the flag controlling whether escapes are preserved during substitution.
781 *
782 * @return The preserve escape flag
783 */
784 public boolean isPreserveEscapes() {
785 return preserveEscapes;
786 }
787
788 /**
789 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
790 * array as a template. The array is not altered by this method.
791 *
792 * @param source the character array to replace in, not altered, null returns null
793 * @return The result of the replace operation
794 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
795 */
796 public String replace(final char[] source) {
797 if (source == null) {
798 return null;
799 }
800 final TextStringBuilder buf = new TextStringBuilder(source.length).append(source);
801 substitute(buf, 0, source.length);
802 return buf.toString();
803 }
804
805 /**
806 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
807 * array as a template. The array is not altered by this method.
808 * <p>
809 * Only the specified portion of the array will be processed. The rest of the array is not processed, and is not
810 * returned.
811 * </p>
812 *
813 * @param source the character array to replace in, not altered, null returns null
814 * @param offset the start offset within the array, must be valid
815 * @param length the length within the array to be processed, must be valid
816 * @return The result of the replace operation
817 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
818 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the
819 * range {@code 0 <= offset <= chars.length}
820 * @throws StringIndexOutOfBoundsException if {@code length < 0}
821 * @throws StringIndexOutOfBoundsException if {@code offset + length > chars.length}
822 */
823 public String replace(final char[] source, final int offset, final int length) {
824 if (source == null) {
825 return null;
826 }
827 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
828 substitute(buf, 0, length);
829 return buf.toString();
830 }
831
832 /**
833 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as
834 * a template. The source is not altered by this method.
835 *
836 * @param source the buffer to use as a template, not changed, null returns null
837 * @return The result of the replace operation
838 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
839 */
840 public String replace(final CharSequence source) {
841 if (source == null) {
842 return null;
843 }
844 return replace(source, 0, source.length());
845 }
846
847 /**
848 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as
849 * a template. The source is not altered by this method.
850 * <p>
851 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not
852 * returned.
853 * </p>
854 *
855 * @param source the buffer to use as a template, not changed, null returns null
856 * @param offset the start offset within the array, must be valid
857 * @param length the length within the array to be processed, must be valid
858 * @return The result of the replace operation
859 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
860 */
861 public String replace(final CharSequence source, final int offset, final int length) {
862 if (source == null) {
863 return null;
864 }
865 final TextStringBuilder buf = new TextStringBuilder(length).append(source.toString(), offset, length);
866 substitute(buf, 0, length);
867 return buf.toString();
868 }
869
870 /**
871 * Replaces all the occurrences of variables in the given source object with their matching values from the
872 * resolver. The input source object is converted to a string using {@code toString} and is not altered.
873 *
874 * @param source the source to replace in, null returns null
875 * @return The result of the replace operation
876 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true
877 */
878 public String replace(final Object source) {
879 if (source == null) {
880 return null;
881 }
882 final TextStringBuilder buf = new TextStringBuilder().append(source);
883 substitute(buf, 0, buf.length());
884 return buf.toString();
885 }
886
887 /**
888 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
889 * string as a template.
890 *
891 * @param source the string to replace in, null returns null
892 * @return The result of the replace operation
893 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
894 */
895 public String replace(final String source) {
896 if (source == null) {
897 return null;
898 }
899 final TextStringBuilder buf = new TextStringBuilder(source);
900 if (!substitute(buf, 0, source.length())) {
901 return source;
902 }
903 return buf.toString();
904 }
905
906 /**
907 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
908 * string as a template.
909 * <p>
910 * Only the specified portion of the string will be processed. The rest of the string is not processed, and is not
911 * returned.
912 * </p>
913 *
914 * @param source the string to replace in, null returns null
915 * @param offset the start offset within the source, must be valid
916 * @param length the length within the source to be processed, must be valid
917 * @return The result of the replace operation
918 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
919 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the
920 * range {@code 0 <= offset <= source.length()}
921 * @throws StringIndexOutOfBoundsException if {@code length < 0}
922 * @throws StringIndexOutOfBoundsException if {@code offset + length > source.length()}
923 */
924 public String replace(final String source, final int offset, final int length) {
925 if (source == null) {
926 return null;
927 }
928 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
929 if (!substitute(buf, 0, length)) {
930 return source.substring(offset, offset + length);
931 }
932 return buf.toString();
933 }
934
935 /**
936 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
937 * buffer as a template. The buffer is not altered by this method.
938 *
939 * @param source the buffer to use as a template, not changed, null returns null
940 * @return The result of the replace operation
941 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
942 */
943 public String replace(final StringBuffer source) {
944 if (source == null) {
945 return null;
946 }
947 final TextStringBuilder buf = new TextStringBuilder(source.length()).append(source);
948 substitute(buf, 0, buf.length());
949 return buf.toString();
950 }
951
952 /**
953 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
954 * buffer as a template. The buffer is not altered by this method.
955 * <p>
956 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not
957 * returned.
958 * </p>
959 *
960 * @param source the buffer to use as a template, not changed, null returns null
961 * @param offset the start offset within the source, must be valid
962 * @param length the length within the source to be processed, must be valid
963 * @return The result of the replace operation
964 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
965 */
966 public String replace(final StringBuffer source, final int offset, final int length) {
967 if (source == null) {
968 return null;
969 }
970 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
971 substitute(buf, 0, length);
972 return buf.toString();
973 }
974
975 /**
976 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
977 * builder as a template. The builder is not altered by this method.
978 *
979 * @param source the builder to use as a template, not changed, null returns null
980 * @return The result of the replace operation
981 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
982 */
983 public String replace(final TextStringBuilder source) {
984 if (source == null) {
985 return null;
986 }
987 final TextStringBuilder builder = new TextStringBuilder(source.length()).append(source);
988 substitute(builder, 0, builder.length());
989 return builder.toString();
990 }
991
992 /**
993 * Replaces all the occurrences of variables with their matching values from the resolver using the given source
994 * builder as a template. The builder is not altered by this method.
995 * <p>
996 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, and is not
997 * returned.
998 * </p>
999 *
1000 * @param source the builder to use as a template, not changed, null returns null
1001 * @param offset the start offset within the source, must be valid
1002 * @param length the length within the source to be processed, must be valid
1003 * @return The result of the replace operation
1004 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1005 */
1006 public String replace(final TextStringBuilder source, final int offset, final int length) {
1007 if (source == null) {
1008 return null;
1009 }
1010 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1011 substitute(buf, 0, length);
1012 return buf.toString();
1013 }
1014
1015 /**
1016 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1017 * resolver. The buffer is updated with the result.
1018 *
1019 * @param source the buffer to replace in, updated, null returns zero
1020 * @return true if altered
1021 */
1022 public boolean replaceIn(final StringBuffer source) {
1023 if (source == null) {
1024 return false;
1025 }
1026 return replaceIn(source, 0, source.length());
1027 }
1028
1029 /**
1030 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1031 * resolver. The buffer is updated with the result.
1032 * <p>
1033 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is
1034 * not deleted.
1035 * </p>
1036 *
1037 * @param source the buffer to replace in, updated, null returns zero
1038 * @param offset the start offset within the source, must be valid
1039 * @param length the length within the source to be processed, must be valid
1040 * @return true if altered
1041 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1042 */
1043 public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
1044 if (source == null) {
1045 return false;
1046 }
1047 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1048 if (!substitute(buf, 0, length)) {
1049 return false;
1050 }
1051 source.replace(offset, offset + length, buf.toString());
1052 return true;
1053 }
1054
1055 /**
1056 * Replaces all the occurrences of variables within the given source buffer with their matching values from the
1057 * resolver. The buffer is updated with the result.
1058 *
1059 * @param source the buffer to replace in, updated, null returns zero
1060 * @return true if altered
1061 */
1062 public boolean replaceIn(final StringBuilder source) {
1063 if (source == null) {
1064 return false;
1065 }
1066 return replaceIn(source, 0, source.length());
1067 }
1068
1069 /**
1070 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1071 * resolver. The builder is updated with the result.
1072 * <p>
1073 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is
1074 * not deleted.
1075 * </p>
1076 *
1077 * @param source the buffer to replace in, updated, null returns zero
1078 * @param offset the start offset within the source, must be valid
1079 * @param length the length within the source to be processed, must be valid
1080 * @return true if altered
1081 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1082 */
1083 public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
1084 if (source == null) {
1085 return false;
1086 }
1087 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length);
1088 if (!substitute(buf, 0, length)) {
1089 return false;
1090 }
1091 source.replace(offset, offset + length, buf.toString());
1092 return true;
1093 }
1094
1095 /**
1096 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1097 * resolver.
1098 *
1099 * @param source the builder to replace in, updated, null returns zero
1100 * @return true if altered
1101 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1102 */
1103 public boolean replaceIn(final TextStringBuilder source) {
1104 if (source == null) {
1105 return false;
1106 }
1107 return substitute(source, 0, source.length());
1108 }
1109
1110 /**
1111 * Replaces all the occurrences of variables within the given source builder with their matching values from the
1112 * resolver.
1113 * <p>
1114 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, but it is
1115 * not deleted.
1116 * </p>
1117 *
1118 * @param source the builder to replace in, null returns zero
1119 * @param offset the start offset within the source, must be valid
1120 * @param length the length within the source to be processed, must be valid
1121 * @return true if altered
1122 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
1123 */
1124 public boolean replaceIn(final TextStringBuilder source, final int offset, final int length) {
1125 if (source == null) {
1126 return false;
1127 }
1128 return substitute(source, offset, length);
1129 }
1130
1131 /**
1132 * Internal method that resolves the value of a variable.
1133 * <p>
1134 * Most users of this class do not need to call this method. This method is called automatically by the substitution
1135 * process.
1136 * </p>
1137 * <p>
1138 * Writers of subclasses can override this method if they need to alter how each substitution occurs. The method is
1139 * passed the variable's name and must return the corresponding value. This implementation uses the
1140 * {@link #getStringLookup()} with the variable's name as the key.
1141 * </p>
1142 *
1143 * @param variableName the name of the variable, not null
1144 * @param buf the buffer where the substitution is occurring, not null
1145 * @param startPos the start position of the variable including the prefix, valid
1146 * @param endPos the end position of the variable including the suffix, valid
1147 * @return The variable's value or <strong>null</strong> if the variable is unknown
1148 */
1149 protected String resolveVariable(final String variableName, final TextStringBuilder buf, final int startPos,
1150 final int endPos) {
1151 final StringLookup resolver = getStringLookup();
1152 if (resolver == null) {
1153 return null;
1154 }
1155 return resolver.lookup(variableName);
1156 }
1157
1158 /**
1159 * Sets a flag whether substitution is done in variable values (recursive).
1160 *
1161 * @param disableSubstitutionInValues true if substitution in variable value are disabled
1162 * @return this, to enable chaining
1163 */
1164 public StringSubstitutor setDisableSubstitutionInValues(final boolean disableSubstitutionInValues) {
1165 this.disableSubstitutionInValues = disableSubstitutionInValues;
1166 return this;
1167 }
1168
1169 /**
1170 * Sets a flag whether substitution is done in variable names. If set to <strong>true</strong>, the names of variables can
1171 * contain other variables which are processed first before the original variable is evaluated, e.g.
1172 * {@code ${jre-${java.version}}}. The default value is <strong>false</strong>.
1173 *
1174 * @param enableSubstitutionInVariables the new value of the flag
1175 * @return this, to enable chaining
1176 */
1177 public StringSubstitutor setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) {
1178 this.enableSubstitutionInVariables = enableSubstitutionInVariables;
1179 return this;
1180 }
1181
1182 /**
1183 * Sets a flag whether exception should be thrown if any variable is undefined.
1184 *
1185 * @param failOnUndefinedVariable true if exception should be thrown on undefined variable
1186 * @return this, to enable chaining
1187 */
1188 public StringSubstitutor setEnableUndefinedVariableException(final boolean failOnUndefinedVariable) {
1189 this.failOnUndefinedVariable = failOnUndefinedVariable;
1190 return this;
1191 }
1192
1193 /**
1194 * Sets the escape character. If this character is placed before a variable reference in the source text, this
1195 * variable will be ignored.
1196 *
1197 * @param escapeChar the escape character (0 for disabling escaping)
1198 * @return this, to enable chaining
1199 */
1200 public StringSubstitutor setEscapeChar(final char escapeChar) {
1201 this.escapeChar = escapeChar;
1202 return this;
1203 }
1204
1205 /**
1206 * Sets a flag controlling whether escapes are preserved during substitution. If set to <strong>true</strong>, the escape
1207 * character is retained during substitution (e.g. {@code $${this-is-escaped}} remains {@code $${this-is-escaped}}).
1208 * If set to <strong>false</strong>, the escape character is removed during substitution (e.g. {@code $${this-is-escaped}}
1209 * becomes {@code ${this-is-escaped}}). The default value is <strong>false</strong>
1210 *
1211 * @param preserveEscapes true if escapes are to be preserved
1212 * @return this, to enable chaining
1213 */
1214 public StringSubstitutor setPreserveEscapes(final boolean preserveEscapes) {
1215 this.preserveEscapes = preserveEscapes;
1216 return this;
1217 }
1218
1219 /**
1220 * Sets the variable default value delimiter to use.
1221 * <p>
1222 * The variable default value delimiter is the character or characters that delimit the variable name and the
1223 * variable default value. This method allows a single character variable default value delimiter to be easily set.
1224 * </p>
1225 *
1226 * @param valueDelimiter the variable default value delimiter character to use
1227 * @return this, to enable chaining
1228 */
1229 public StringSubstitutor setValueDelimiter(final char valueDelimiter) {
1230 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.charMatcher(valueDelimiter));
1231 }
1232
1233 /**
1234 * Sets the variable default value delimiter to use.
1235 * <p>
1236 * The variable default value delimiter is the character or characters that delimit the variable name and the
1237 * variable default value. This method allows a string variable default value delimiter to be easily set.
1238 * </p>
1239 * <p>
1240 * If the {@code valueDelimiter} is null or empty string, then the variable default value resolution becomes
1241 * disabled.
1242 * </p>
1243 *
1244 * @param valueDelimiter the variable default value delimiter string to use, may be null or empty
1245 * @return this, to enable chaining
1246 */
1247 public StringSubstitutor setValueDelimiter(final String valueDelimiter) {
1248 if (valueDelimiter == null || valueDelimiter.isEmpty()) {
1249 setValueDelimiterMatcher(null);
1250 return this;
1251 }
1252 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.stringMatcher(valueDelimiter));
1253 }
1254
1255 /**
1256 * Sets the variable default value delimiter matcher to use.
1257 * <p>
1258 * The variable default value delimiter is the character or characters that delimit the variable name and the
1259 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default
1260 * value delimiter matches.
1261 * </p>
1262 * <p>
1263 * If the {@code valueDelimiterMatcher} is null, then the variable default value resolution becomes disabled.
1264 * </p>
1265 *
1266 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null
1267 * @return this, to enable chaining
1268 */
1269 public StringSubstitutor setValueDelimiterMatcher(final StringMatcher valueDelimiterMatcher) {
1270 this.valueDelimiterMatcher = valueDelimiterMatcher;
1271 return this;
1272 }
1273
1274 /**
1275 * Sets the variable prefix to use.
1276 * <p>
1277 * The variable prefix is the character or characters that identify the start of a variable. This method allows a
1278 * single character prefix to be easily set.
1279 * </p>
1280 *
1281 * @param prefix the prefix character to use
1282 * @return this, to enable chaining
1283 */
1284 public StringSubstitutor setVariablePrefix(final char prefix) {
1285 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.charMatcher(prefix));
1286 }
1287
1288 /**
1289 * Sets the variable prefix to use.
1290 * <p>
1291 * The variable prefix is the character or characters that identify the start of a variable. This method allows a
1292 * string prefix to be easily set.
1293 * </p>
1294 *
1295 * @param prefix the prefix for variables, not null
1296 * @return this, to enable chaining
1297 * @throws IllegalArgumentException if the prefix is null
1298 */
1299 public StringSubstitutor setVariablePrefix(final String prefix) {
1300 Validate.isTrue(prefix != null, "Variable prefix must not be null!");
1301 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(prefix));
1302 }
1303
1304 /**
1305 * Sets the variable prefix matcher currently in use.
1306 * <p>
1307 * The variable prefix is the character or characters that identify the start of a variable. This prefix is
1308 * expressed in terms of a matcher allowing advanced prefix matches.
1309 * </p>
1310 *
1311 * @param prefixMatcher the prefix matcher to use, null ignored
1312 * @return this, to enable chaining
1313 * @throws IllegalArgumentException if the prefix matcher is null
1314 */
1315 public StringSubstitutor setVariablePrefixMatcher(final StringMatcher prefixMatcher) {
1316 Validate.isTrue(prefixMatcher != null, "Variable prefix matcher must not be null!");
1317 this.prefixMatcher = prefixMatcher;
1318 return this;
1319 }
1320
1321 /**
1322 * Sets the VariableResolver that is used to lookup variables.
1323 *
1324 * @param variableResolver the VariableResolver
1325 * @return this, to enable chaining
1326 */
1327 public StringSubstitutor setVariableResolver(final StringLookup variableResolver) {
1328 this.variableResolver = variableResolver;
1329 return this;
1330 }
1331
1332 /**
1333 * Sets the variable suffix to use.
1334 * <p>
1335 * The variable suffix is the character or characters that identify the end of a variable. This method allows a
1336 * single character suffix to be easily set.
1337 * </p>
1338 *
1339 * @param suffix the suffix character to use
1340 * @return this, to enable chaining
1341 */
1342 public StringSubstitutor setVariableSuffix(final char suffix) {
1343 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.charMatcher(suffix));
1344 }
1345
1346 /**
1347 * Sets the variable suffix to use.
1348 * <p>
1349 * The variable suffix is the character or characters that identify the end of a variable. This method allows a
1350 * string suffix to be easily set.
1351 * </p>
1352 *
1353 * @param suffix the suffix for variables, not null
1354 * @return this, to enable chaining
1355 * @throws IllegalArgumentException if the suffix is null
1356 */
1357 public StringSubstitutor setVariableSuffix(final String suffix) {
1358 Validate.isTrue(suffix != null, "Variable suffix must not be null!");
1359 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(suffix));
1360 }
1361
1362 /**
1363 * Sets the variable suffix matcher currently in use.
1364 * <p>
1365 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed
1366 * in terms of a matcher allowing advanced suffix matches.
1367 * </p>
1368 *
1369 * @param suffixMatcher the suffix matcher to use, null ignored
1370 * @return this, to enable chaining
1371 * @throws IllegalArgumentException if the suffix matcher is null
1372 */
1373 public StringSubstitutor setVariableSuffixMatcher(final StringMatcher suffixMatcher) {
1374 Validate.isTrue(suffixMatcher != null, "Variable suffix matcher must not be null!");
1375 this.suffixMatcher = suffixMatcher;
1376 return this;
1377 }
1378
1379 /**
1380 * Internal method that substitutes the variables.
1381 * <p>
1382 * Most users of this class do not need to call this method. This method will be called automatically by another
1383 * (public) method.
1384 * </p>
1385 * <p>
1386 * Writers of subclasses can override this method if they need access to the substitution process at the start or
1387 * end.
1388 * </p>
1389 *
1390 * @param builder the string builder to substitute into, not null
1391 * @param offset the start offset within the builder, must be valid
1392 * @param length the length within the builder to be processed, must be valid
1393 * @return true if altered
1394 */
1395 protected boolean substitute(final TextStringBuilder builder, final int offset, final int length) {
1396 return substitute(builder, offset, length, null).altered;
1397 }
1398
1399 /**
1400 * Recursive handler for multiple levels of interpolation. This is the main interpolation method, which resolves the
1401 * values of all variable references contained in the passed in text.
1402 *
1403 * @param builder the string builder to substitute into, not null
1404 * @param offset the start offset within the builder, must be valid
1405 * @param length the length within the builder to be processed, must be valid
1406 * @param priorVariables the stack keeping track of the replaced variables, may be null
1407 * @return The result.
1408 * @throws IllegalArgumentException if variable is not found and <pre>isEnableUndefinedVariableException()==true</pre>
1409 * @since 1.9
1410 */
1411 private Result substitute(final TextStringBuilder builder, final int offset, final int length,
1412 List<String> priorVariables) {
1413 Objects.requireNonNull(builder, "builder");
1414 final StringMatcher prefixMatcher = getVariablePrefixMatcher();
1415 final StringMatcher suffixMatcher = getVariableSuffixMatcher();
1416 final char escapeCh = getEscapeChar();
1417 final StringMatcher valueDelimMatcher = getValueDelimiterMatcher();
1418 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
1419 final boolean substitutionInValuesDisabled = isDisableSubstitutionInValues();
1420 final boolean undefinedVariableException = isEnableUndefinedVariableException();
1421 final boolean preserveEscapes = isPreserveEscapes();
1422
1423 boolean altered = false;
1424 int lengthChange = 0;
1425 int bufEnd = offset + length;
1426 int pos = offset;
1427 int escPos = -1;
1428 outer: while (pos < bufEnd) {
1429 final int startMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd);
1430 if (startMatchLen == 0) {
1431 pos++;
1432 } else {
1433 // found variable start marker
1434 if (pos > offset && builder.charAt(pos - 1) == escapeCh) {
1435 // escape detected
1436 if (preserveEscapes) {
1437 // keep escape
1438 pos++;
1439 continue;
1440 }
1441 // mark esc ch for deletion if we find a complete variable
1442 escPos = pos - 1;
1443 }
1444 // find suffix
1445 int startPos = pos;
1446 pos += startMatchLen;
1447 int endMatchLen = 0;
1448 int nestedVarCount = 0;
1449 while (pos < bufEnd) {
1450 if (substitutionInVariablesEnabled && prefixMatcher.isMatch(builder, pos, offset, bufEnd) != 0) {
1451 // found a nested variable start
1452 endMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd);
1453 nestedVarCount++;
1454 pos += endMatchLen;
1455 continue;
1456 }
1457
1458 endMatchLen = suffixMatcher.isMatch(builder, pos, offset, bufEnd);
1459 if (endMatchLen == 0) {
1460 pos++;
1461 } else {
1462 // found variable end marker
1463 if (nestedVarCount == 0) {
1464 if (escPos >= 0) {
1465 // delete escape
1466 builder.deleteCharAt(escPos);
1467 escPos = -1;
1468 lengthChange--;
1469 altered = true;
1470 bufEnd--;
1471 pos = startPos + 1;
1472 startPos--;
1473 continue outer;
1474 }
1475 // get var name
1476 String varNameExpr = builder.midString(startPos + startMatchLen,
1477 pos - startPos - startMatchLen);
1478 if (substitutionInVariablesEnabled) {
1479 final TextStringBuilder bufName = new TextStringBuilder(varNameExpr);
1480 substitute(bufName, 0, bufName.length());
1481 varNameExpr = bufName.toString();
1482 }
1483 pos += endMatchLen;
1484 final int endPos = pos;
1485
1486 String varName = varNameExpr;
1487 String varDefaultValue = null;
1488
1489 if (valueDelimMatcher != null) {
1490 final char[] varNameExprChars = varNameExpr.toCharArray();
1491 int valueDelimiterMatchLen = 0;
1492 for (int i = 0; i < varNameExprChars.length; i++) {
1493 // if there's any nested variable when nested variable substitution disabled,
1494 // then stop resolving name and default value.
1495 if (!substitutionInVariablesEnabled && prefixMatcher.isMatch(varNameExprChars, i, i,
1496 varNameExprChars.length) != 0) {
1497 break;
1498 }
1499 if (valueDelimMatcher.isMatch(varNameExprChars, i, 0,
1500 varNameExprChars.length) != 0) {
1501 valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i, 0,
1502 varNameExprChars.length);
1503 varName = varNameExpr.substring(0, i);
1504 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
1505 break;
1506 }
1507 }
1508 }
1509
1510 // on the first call initialize priorVariables
1511 if (priorVariables == null) {
1512 priorVariables = new ArrayList<>();
1513 priorVariables.add(builder.midString(offset, length));
1514 }
1515
1516 // handle cyclic substitution
1517 checkCyclicSubstitution(varName, priorVariables);
1518 priorVariables.add(varName);
1519
1520 // resolve the variable
1521 String varValue = resolveVariable(varName, builder, startPos, endPos);
1522 if (varValue == null) {
1523 varValue = varDefaultValue;
1524 }
1525 if (varValue != null) {
1526 final int varLen = varValue.length();
1527 builder.replace(startPos, endPos, varValue);
1528 altered = true;
1529 int change = 0;
1530 if (!substitutionInValuesDisabled) { // recursive replace
1531 change = substitute(builder, startPos, varLen, priorVariables).lengthChange;
1532 }
1533 change = change + varLen - (endPos - startPos);
1534 pos += change;
1535 bufEnd += change;
1536 lengthChange += change;
1537 } else if (undefinedVariableException) {
1538 throw new IllegalArgumentException(
1539 String.format("Cannot resolve variable '%s' (enableSubstitutionInVariables=%s).",
1540 varName, substitutionInVariablesEnabled));
1541 }
1542
1543 // remove variable from the cyclic stack
1544 priorVariables.remove(priorVariables.size() - 1);
1545 break;
1546 }
1547 nestedVarCount--;
1548 pos += endMatchLen;
1549 }
1550 }
1551 }
1552 }
1553 return new Result(altered, lengthChange);
1554 }
1555
1556 /**
1557 * Returns a string representation of the object.
1558 *
1559 * @return a string representation of the object.
1560 * @since 1.11.0
1561 */
1562 @Override
1563 public String toString() {
1564 // @formatter:off
1565 return new StringBuilder()
1566 .append("StringSubstitutor [disableSubstitutionInValues=")
1567 .append(disableSubstitutionInValues)
1568 .append(", enableSubstitutionInVariables=")
1569 .append(enableSubstitutionInVariables)
1570 .append(", enableUndefinedVariableException=")
1571 .append(failOnUndefinedVariable)
1572 .append(", escapeChar=")
1573 .append(escapeChar)
1574 .append(", prefixMatcher=")
1575 .append(prefixMatcher)
1576 .append(", preserveEscapes=")
1577 .append(preserveEscapes)
1578 .append(", suffixMatcher=")
1579 .append(suffixMatcher)
1580 .append(", valueDelimiterMatcher=")
1581 .append(valueDelimiterMatcher)
1582 .append(", variableResolver=")
1583 .append(variableResolver)
1584 .append("]")
1585 .toString();
1586 // @formatter:on
1587 }
1588 }