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.lang3.text;
18
19 import java.util.ArrayList;
20 import java.util.Enumeration;
21 import java.util.HashMap;
22 import java.util.List;
23 import java.util.Map;
24 import java.util.Objects;
25 import java.util.Properties;
26
27 import org.apache.commons.lang3.StringUtils;
28
29 /**
30 * Substitutes variables within a string by values.
31 * <p>
32 * This class takes a piece of text and substitutes all the variables within it.
33 * The default definition of a variable is {@code ${variableName}}.
34 * The prefix and suffix can be changed via constructors and set methods.
35 * </p>
36 * <p>
37 * Variable values are typically resolved from a map, but could also be resolved
38 * from system properties, or by supplying a custom variable resolver.
39 * </p>
40 * <p>
41 * The simplest example is to use this class to replace Java System properties. For example:
42 * </p>
43 * <pre>
44 * StrSubstitutor.replaceSystemProperties(
45 * "You are running with java.version = ${java.version} and os.name = ${os.name}.");
46 * </pre>
47 * <p>
48 * Typical usage of this class follows the following pattern: First an instance is created
49 * and initialized with the map that contains the values for the available variables.
50 * If a prefix and/or suffix for variables should be used other than the default ones,
51 * the appropriate settings can be performed. After that the {@code replace()}
52 * method can be called passing in the source text for interpolation. In the returned
53 * text all variable references (as long as their values are known) will be resolved.
54 * The following example demonstrates this:
55 * </p>
56 * <pre>
57 * Map valuesMap = HashMap();
58 * valuesMap.put("animal", "quick brown fox");
59 * valuesMap.put("target", "lazy dog");
60 * String templateString = "The ${animal} jumps over the ${target}.";
61 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
62 * String resolvedString = sub.replace(templateString);
63 * </pre>
64 * yielding:
65 * <pre>
66 * The quick brown fox jumps over the lazy dog.
67 * </pre>
68 * <p>
69 * Also, this class allows to set a default value for unresolved variables.
70 * The default value for a variable can be appended to the variable name after the variable
71 * default value delimiter. The default value of the variable default value delimiter is ':-',
72 * as in bash and other *nix shells, as those are arguably where the default ${} delimiter set originated.
73 * The variable default value delimiter can be manually set by calling {@link #setValueDelimiterMatcher(StrMatcher)},
74 * {@link #setValueDelimiter(char)} or {@link #setValueDelimiter(String)}.
75 * The following shows an example with variable default value settings:
76 * </p>
77 * <pre>
78 * Map valuesMap = HashMap();
79 * valuesMap.put("animal", "quick brown fox");
80 * valuesMap.put("target", "lazy dog");
81 * String templateString = "The ${animal} jumps over the ${target}. ${undefined.number:-1234567890}.";
82 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
83 * String resolvedString = sub.replace(templateString);
84 * </pre>
85 * <p>
86 * yielding:
87 * </p>
88 * <pre>
89 * The quick brown fox jumps over the lazy dog. 1234567890.
90 * </pre>
91 * <p>
92 * In addition to this usage pattern there are some static convenience methods that
93 * cover the most common use cases. These methods can be used without the need of
94 * manually creating an instance. However if multiple replace operations are to be
95 * performed, creating and reusing an instance of this class will be more efficient.
96 * </p>
97 * <p>
98 * Variable replacement works in a recursive way. Thus, if a variable value contains
99 * a variable then that variable will also be replaced. Cyclic replacements are
100 * detected and will cause an exception to be thrown.
101 * </p>
102 * <p>
103 * Sometimes the interpolation's result must contain a variable prefix. As an example
104 * take the following source text:
105 * </p>
106 * <pre>
107 * The variable ${${name}} must be used.
108 * </pre>
109 * <p>
110 * Here only the variable's name referred to in the text should be replaced resulting
111 * in the text (assuming that the value of the {@code name} variable is {@code x}):
112 * </p>
113 * <pre>
114 * The variable ${x} must be used.
115 * </pre>
116 * <p>
117 * To achieve this effect there are two possibilities: Either set a different prefix
118 * and suffix for variables which do not conflict with the result text you want to
119 * produce. The other possibility is to use the escape character, by default '$'.
120 * If this character is placed before a variable reference, this reference is ignored
121 * and won't be replaced. For example:
122 * </p>
123 * <pre>
124 * The variable $${${name}} must be used.
125 * </pre>
126 * <p>
127 * In some complex scenarios you might even want to perform substitution in the
128 * names of variables, for instance:
129 * </p>
130 * <pre>
131 * ${jre-${java.specification.version}}
132 * </pre>
133 * <p>
134 * {@link StrSubstitutor} supports this recursive substitution in variable
135 * names, but it has to be enabled explicitly by setting the
136 * {@link #setEnableSubstitutionInVariables(boolean) enableSubstitutionInVariables}
137 * property to <b>true</b>.
138 * </p>
139 * <p>
140 * This class is <b>not</b> thread safe.
141 * </p>
142 *
143 * @since 2.2
144 * @deprecated As of 3.6, use Apache Commons Text
145 * <a href="https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/StringSubstitutor.html">
146 * StringSubstitutor</a> instead
147 */
148 @Deprecated
149 public class StrSubstitutor {
150
151 /**
152 * Constant for the default escape character.
153 */
154 public static final char DEFAULT_ESCAPE = '$';
155 /**
156 * Constant for the default variable prefix.
157 */
158 public static final StrMatcher DEFAULT_PREFIX = StrMatcher.stringMatcher("${");
159 /**
160 * Constant for the default variable suffix.
161 */
162 public static final StrMatcher DEFAULT_SUFFIX = StrMatcher.stringMatcher("}");
163 /**
164 * Constant for the default value delimiter of a variable.
165 * @since 3.2
166 */
167 public static final StrMatcher DEFAULT_VALUE_DELIMITER = StrMatcher.stringMatcher(":-");
168
169 /**
170 * Stores the escape character.
171 */
172 private char escapeChar;
173 /**
174 * Stores the variable prefix.
175 */
176 private StrMatcher prefixMatcher;
177 /**
178 * Stores the variable suffix.
179 */
180 private StrMatcher suffixMatcher;
181 /**
182 * Stores the default variable value delimiter
183 */
184 private StrMatcher valueDelimiterMatcher;
185 /**
186 * Variable resolution is delegated to an implementor of VariableResolver.
187 */
188 private StrLookup<?> variableResolver;
189 /**
190 * The flag whether substitution in variable names is enabled.
191 */
192 private boolean enableSubstitutionInVariables;
193 /**
194 * Whether escapes should be preserved. Default is false;
195 */
196 private boolean preserveEscapes;
197
198 /**
199 * Replaces all the occurrences of variables in the given source object with
200 * their matching values from the map.
201 *
202 * @param <V> the type of the values in the map
203 * @param source the source text containing the variables to substitute, null returns null
204 * @param valueMap the map with the values, may be null
205 * @return the result of the replace operation
206 */
207 public static <V> String replace(final Object source, final Map<String, V> valueMap) {
208 return new StrSubstitutor(valueMap).replace(source);
209 }
210
211 /**
212 * Replaces all the occurrences of variables in the given source object with
213 * their matching values from the map. This method allows to specify a
214 * custom variable prefix and suffix
215 *
216 * @param <V> the type of the values in the map
217 * @param source the source text containing the variables to substitute, null returns null
218 * @param valueMap the map with the values, may be null
219 * @param prefix the prefix of variables, not null
220 * @param suffix the suffix of variables, not null
221 * @return the result of the replace operation
222 * @throws IllegalArgumentException if the prefix or suffix is null
223 */
224 public static <V> String replace(final Object source, final Map<String, V> valueMap, final String prefix, final String suffix) {
225 return new StrSubstitutor(valueMap, prefix, suffix).replace(source);
226 }
227
228 /**
229 * Replaces all the occurrences of variables in the given source object with their matching
230 * values from the properties.
231 *
232 * @param source the source text containing the variables to substitute, null returns null
233 * @param valueProperties the properties with values, may be null
234 * @return the result of the replace operation
235 */
236 public static String replace(final Object source, final Properties valueProperties) {
237 if (valueProperties == null) {
238 return source.toString();
239 }
240 final Map<String, String> valueMap = new HashMap<>();
241 final Enumeration<?> propNames = valueProperties.propertyNames();
242 while (propNames.hasMoreElements()) {
243 final String propName = String.valueOf(propNames.nextElement());
244 final String propValue = valueProperties.getProperty(propName);
245 valueMap.put(propName, propValue);
246 }
247 return replace(source, valueMap);
248 }
249
250 /**
251 * Replaces all the occurrences of variables in the given source object with
252 * their matching values from the system properties.
253 *
254 * @param source the source text containing the variables to substitute, null returns null
255 * @return the result of the replace operation
256 */
257 public static String replaceSystemProperties(final Object source) {
258 return new StrSubstitutor(StrLookup.systemPropertiesLookup()).replace(source);
259 }
260
261 /**
262 * Creates a new instance with defaults for variable prefix and suffix
263 * and the escaping character.
264 */
265 public StrSubstitutor() {
266 this(null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
267 }
268
269 /**
270 * Creates a new instance and initializes it. Uses defaults for variable
271 * prefix and suffix and the escaping character.
272 *
273 * @param <V> the type of the values in the map
274 * @param valueMap the map with the variables' values, may be null
275 */
276 public <V> StrSubstitutor(final Map<String, V> valueMap) {
277 this(StrLookup.mapLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
278 }
279
280 /**
281 * Creates a new instance and initializes it. Uses a default escaping character.
282 *
283 * @param <V> the type of the values in the map
284 * @param valueMap the map with the variables' values, may be null
285 * @param prefix the prefix for variables, not null
286 * @param suffix the suffix for variables, not null
287 * @throws IllegalArgumentException if the prefix or suffix is null
288 */
289 public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix) {
290 this(StrLookup.mapLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE);
291 }
292
293 /**
294 * Creates a new instance and initializes it.
295 *
296 * @param <V> the type of the values in the map
297 * @param valueMap the map with the variables' values, may be null
298 * @param prefix the prefix for variables, not null
299 * @param suffix the suffix for variables, not null
300 * @param escape the escape character
301 * @throws IllegalArgumentException if the prefix or suffix is null
302 */
303 public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
304 final char escape) {
305 this(StrLookup.mapLookup(valueMap), prefix, suffix, escape);
306 }
307
308 /**
309 * Creates a new instance and initializes it.
310 *
311 * @param <V> the type of the values in the map
312 * @param valueMap the map with the variables' values, may be null
313 * @param prefix the prefix for variables, not null
314 * @param suffix the suffix for variables, not null
315 * @param escape the escape character
316 * @param valueDelimiter the variable default value delimiter, may be null
317 * @throws IllegalArgumentException if the prefix or suffix is null
318 * @since 3.2
319 */
320 public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
321 final char escape, final String valueDelimiter) {
322 this(StrLookup.mapLookup(valueMap), prefix, suffix, escape, valueDelimiter);
323 }
324
325 /**
326 * Creates a new instance and initializes it.
327 *
328 * @param variableResolver the variable resolver, may be null
329 */
330 public StrSubstitutor(final StrLookup<?> variableResolver) {
331 this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
332 }
333
334 /**
335 * Creates a new instance and initializes it.
336 *
337 * @param variableResolver the variable resolver, may be null
338 * @param prefix the prefix for variables, not null
339 * @param suffix the suffix for variables, not null
340 * @param escape the escape character
341 * @throws IllegalArgumentException if the prefix or suffix is null
342 */
343 public StrSubstitutor(final StrLookup<?> variableResolver, final String prefix, final String suffix,
344 final char escape) {
345 this.setVariableResolver(variableResolver);
346 this.setVariablePrefix(prefix);
347 this.setVariableSuffix(suffix);
348 this.setEscapeChar(escape);
349 this.setValueDelimiterMatcher(DEFAULT_VALUE_DELIMITER);
350 }
351
352 /**
353 * Creates a new instance and initializes it.
354 *
355 * @param variableResolver the variable resolver, may be null
356 * @param prefix the prefix for variables, not null
357 * @param suffix the suffix for variables, not null
358 * @param escape the escape character
359 * @param valueDelimiter the variable default value delimiter string, may be null
360 * @throws IllegalArgumentException if the prefix or suffix is null
361 * @since 3.2
362 */
363 public StrSubstitutor(final StrLookup<?> variableResolver, final String prefix, final String suffix,
364 final char escape, final String valueDelimiter) {
365 this.setVariableResolver(variableResolver);
366 this.setVariablePrefix(prefix);
367 this.setVariableSuffix(suffix);
368 this.setEscapeChar(escape);
369 this.setValueDelimiter(valueDelimiter);
370 }
371
372 /**
373 * Creates a new instance and initializes it.
374 *
375 * @param variableResolver the variable resolver, may be null
376 * @param prefixMatcher the prefix for variables, not null
377 * @param suffixMatcher the suffix for variables, not null
378 * @param escape the escape character
379 * @throws IllegalArgumentException if the prefix or suffix is null
380 */
381 public StrSubstitutor(
382 final StrLookup<?> variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher,
383 final char escape) {
384 this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER);
385 }
386
387 /**
388 * Creates a new instance and initializes it.
389 *
390 * @param variableResolver the variable resolver, may be null
391 * @param prefixMatcher the prefix for variables, not null
392 * @param suffixMatcher the suffix for variables, not null
393 * @param escape the escape character
394 * @param valueDelimiterMatcher the variable default value delimiter matcher, may be null
395 * @throws IllegalArgumentException if the prefix or suffix is null
396 * @since 3.2
397 */
398 public StrSubstitutor(
399 final StrLookup<?> variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher,
400 final char escape, final StrMatcher valueDelimiterMatcher) {
401 this.setVariableResolver(variableResolver);
402 this.setVariablePrefixMatcher(prefixMatcher);
403 this.setVariableSuffixMatcher(suffixMatcher);
404 this.setEscapeChar(escape);
405 this.setValueDelimiterMatcher(valueDelimiterMatcher);
406 }
407
408 /**
409 * Replaces all the occurrences of variables with their matching values
410 * from the resolver using the given source string as a template.
411 *
412 * @param source the string to replace in, null returns null
413 * @return the result of the replace operation
414 */
415 public String replace(final String source) {
416 if (source == null) {
417 return null;
418 }
419 final StrBuilder buf = new StrBuilder(source);
420 if (!substitute(buf, 0, source.length())) {
421 return source;
422 }
423 return buf.toString();
424 }
425
426 /**
427 * Replaces all the occurrences of variables with their matching values
428 * from the resolver using the given source string as a template.
429 * <p>
430 * Only the specified portion of the string will be processed.
431 * The rest of the string is not processed, and is not returned.
432 * </p>
433 *
434 * @param source the string to replace in, null returns null
435 * @param offset the start offset within the array, must be valid
436 * @param length the length within the array to be processed, must be valid
437 * @return the result of the replace operation
438 */
439 public String replace(final String source, final int offset, final int length) {
440 if (source == null) {
441 return null;
442 }
443 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
444 if (!substitute(buf, 0, length)) {
445 return source.substring(offset, offset + length);
446 }
447 return buf.toString();
448 }
449
450 /**
451 * Replaces all the occurrences of variables with their matching values
452 * from the resolver using the given source array as a template.
453 * The array is not altered by this method.
454 *
455 * @param source the character array to replace in, not altered, null returns null
456 * @return the result of the replace operation
457 */
458 public String replace(final char[] source) {
459 if (source == null) {
460 return null;
461 }
462 final StrBuilder buf = new StrBuilder(source.length).append(source);
463 substitute(buf, 0, source.length);
464 return buf.toString();
465 }
466
467 /**
468 * Replaces all the occurrences of variables with their matching values
469 * from the resolver using the given source array as a template.
470 * The array is not altered by this method.
471 * <p>
472 * Only the specified portion of the array will be processed.
473 * The rest of the array is not processed, and is not returned.
474 * </p>
475 *
476 * @param source the character array to replace in, not altered, null returns null
477 * @param offset the start offset within the array, must be valid
478 * @param length the length within the array to be processed, must be valid
479 * @return the result of the replace operation
480 */
481 public String replace(final char[] source, final int offset, final int length) {
482 if (source == null) {
483 return null;
484 }
485 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
486 substitute(buf, 0, length);
487 return buf.toString();
488 }
489
490 /**
491 * Replaces all the occurrences of variables with their matching values
492 * from the resolver using the given source buffer as a template.
493 * The buffer is not altered by this method.
494 *
495 * @param source the buffer to use as a template, not changed, null returns null
496 * @return the result of the replace operation
497 */
498 public String replace(final StringBuffer source) {
499 if (source == null) {
500 return null;
501 }
502 final StrBuilder buf = new StrBuilder(source.length()).append(source);
503 substitute(buf, 0, buf.length());
504 return buf.toString();
505 }
506
507 /**
508 * Replaces all the occurrences of variables with their matching values
509 * from the resolver using the given source buffer as a template.
510 * The buffer is not altered by this method.
511 * <p>
512 * Only the specified portion of the buffer will be processed.
513 * The rest of the buffer is not processed, and is not returned.
514 * </p>
515 *
516 * @param source the buffer to use as a template, not changed, null returns null
517 * @param offset the start offset within the array, must be valid
518 * @param length the length within the array to be processed, must be valid
519 * @return the result of the replace operation
520 */
521 public String replace(final StringBuffer source, final int offset, final int length) {
522 if (source == null) {
523 return null;
524 }
525 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
526 substitute(buf, 0, length);
527 return buf.toString();
528 }
529
530 /**
531 * Replaces all the occurrences of variables with their matching values
532 * from the resolver using the given source as a template.
533 * The source is not altered by this method.
534 *
535 * @param source the buffer to use as a template, not changed, null returns null
536 * @return the result of the replace operation
537 * @since 3.2
538 */
539 public String replace(final CharSequence source) {
540 if (source == null) {
541 return null;
542 }
543 return replace(source, 0, source.length());
544 }
545
546 /**
547 * Replaces all the occurrences of variables with their matching values
548 * from the resolver using the given source as a template.
549 * The source is not altered by this method.
550 * <p>
551 * Only the specified portion of the buffer will be processed.
552 * The rest of the buffer is not processed, and is not returned.
553 * </p>
554 *
555 * @param source the buffer to use as a template, not changed, null returns null
556 * @param offset the start offset within the array, must be valid
557 * @param length the length within the array to be processed, must be valid
558 * @return the result of the replace operation
559 * @since 3.2
560 */
561 public String replace(final CharSequence source, final int offset, final int length) {
562 if (source == null) {
563 return null;
564 }
565 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
566 substitute(buf, 0, length);
567 return buf.toString();
568 }
569
570 /**
571 * Replaces all the occurrences of variables with their matching values
572 * from the resolver using the given source builder as a template.
573 * The builder is not altered by this method.
574 *
575 * @param source the builder to use as a template, not changed, null returns null
576 * @return the result of the replace operation
577 */
578 public String replace(final StrBuilder source) {
579 if (source == null) {
580 return null;
581 }
582 final StrBuilder buf = new StrBuilder(source.length()).append(source);
583 substitute(buf, 0, buf.length());
584 return buf.toString();
585 }
586
587 /**
588 * Replaces all the occurrences of variables with their matching values
589 * from the resolver using the given source builder as a template.
590 * The builder is not altered by this method.
591 * <p>
592 * Only the specified portion of the builder will be processed.
593 * The rest of the builder is not processed, and is not returned.
594 * </p>
595 *
596 * @param source the builder to use as a template, not changed, null returns null
597 * @param offset the start offset within the array, must be valid
598 * @param length the length within the array to be processed, must be valid
599 * @return the result of the replace operation
600 */
601 public String replace(final StrBuilder source, final int offset, final int length) {
602 if (source == null) {
603 return null;
604 }
605 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
606 substitute(buf, 0, length);
607 return buf.toString();
608 }
609
610 /**
611 * Replaces all the occurrences of variables in the given source object with
612 * their matching values from the resolver. The input source object is
613 * converted to a string using {@code toString} and is not altered.
614 *
615 * @param source the source to replace in, null returns null
616 * @return the result of the replace operation
617 */
618 public String replace(final Object source) {
619 if (source == null) {
620 return null;
621 }
622 final StrBuilder buf = new StrBuilder().append(source);
623 substitute(buf, 0, buf.length());
624 return buf.toString();
625 }
626
627 /**
628 * Replaces all the occurrences of variables within the given source buffer
629 * with their matching values from the resolver.
630 * The buffer is updated with the result.
631 *
632 * @param source the buffer to replace in, updated, null returns zero
633 * @return true if altered
634 */
635 public boolean replaceIn(final StringBuffer source) {
636 if (source == null) {
637 return false;
638 }
639 return replaceIn(source, 0, source.length());
640 }
641
642 /**
643 * Replaces all the occurrences of variables within the given source buffer
644 * with their matching values from the resolver.
645 * The buffer is updated with the result.
646 * <p>
647 * Only the specified portion of the buffer will be processed.
648 * The rest of the buffer is not processed, but it is not deleted.
649 * </p>
650 *
651 * @param source the buffer to replace in, updated, null returns zero
652 * @param offset the start offset within the array, must be valid
653 * @param length the length within the buffer to be processed, must be valid
654 * @return true if altered
655 */
656 public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
657 if (source == null) {
658 return false;
659 }
660 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
661 if (!substitute(buf, 0, length)) {
662 return false;
663 }
664 source.replace(offset, offset + length, buf.toString());
665 return true;
666 }
667
668 /**
669 * Replaces all the occurrences of variables within the given source buffer
670 * with their matching values from the resolver.
671 * The buffer is updated with the result.
672 *
673 * @param source the buffer to replace in, updated, null returns zero
674 * @return true if altered
675 * @since 3.2
676 */
677 public boolean replaceIn(final StringBuilder source) {
678 if (source == null) {
679 return false;
680 }
681 return replaceIn(source, 0, source.length());
682 }
683
684 /**
685 * Replaces all the occurrences of variables within the given source builder
686 * with their matching values from the resolver.
687 * The builder is updated with the result.
688 * <p>
689 * Only the specified portion of the buffer will be processed.
690 * The rest of the buffer is not processed, but it is not deleted.
691 * </p>
692 *
693 * @param source the buffer to replace in, updated, null returns zero
694 * @param offset the start offset within the array, must be valid
695 * @param length the length within the buffer to be processed, must be valid
696 * @return true if altered
697 * @since 3.2
698 */
699 public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
700 if (source == null) {
701 return false;
702 }
703 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
704 if (!substitute(buf, 0, length)) {
705 return false;
706 }
707 source.replace(offset, offset + length, buf.toString());
708 return true;
709 }
710
711 /**
712 * Replaces all the occurrences of variables within the given source
713 * builder with their matching values from the resolver.
714 *
715 * @param source the builder to replace in, updated, null returns zero
716 * @return true if altered
717 */
718 public boolean replaceIn(final StrBuilder source) {
719 if (source == null) {
720 return false;
721 }
722 return substitute(source, 0, source.length());
723 }
724
725 /**
726 * Replaces all the occurrences of variables within the given source
727 * builder with their matching values from the resolver.
728 * <p>
729 * Only the specified portion of the builder will be processed.
730 * The rest of the builder is not processed, but it is not deleted.
731 * </p>
732 *
733 * @param source the builder to replace in, null returns zero
734 * @param offset the start offset within the array, must be valid
735 * @param length the length within the builder to be processed, must be valid
736 * @return true if altered
737 */
738 public boolean replaceIn(final StrBuilder source, final int offset, final int length) {
739 if (source == null) {
740 return false;
741 }
742 return substitute(source, offset, length);
743 }
744
745 /**
746 * Internal method that substitutes the variables.
747 * <p>
748 * Most users of this class do not need to call this method. This method will
749 * be called automatically by another (public) method.
750 * </p>
751 * <p>
752 * Writers of subclasses can override this method if they need access to
753 * the substitution process at the start or end.
754 * </p>
755 *
756 * @param buf the string builder to substitute into, not null
757 * @param offset the start offset within the builder, must be valid
758 * @param length the length within the builder to be processed, must be valid
759 * @return true if altered
760 */
761 protected boolean substitute(final StrBuilder buf, final int offset, final int length) {
762 return substitute(buf, offset, length, null) > 0;
763 }
764
765 /**
766 * Recursive handler for multiple levels of interpolation. This is the main
767 * interpolation method, which resolves the values of all variable references
768 * contained in the passed-in text.
769 *
770 * @param buf the string builder to substitute into, not null
771 * @param offset the start offset within the builder, must be valid
772 * @param length the length within the builder to be processed, must be valid
773 * @param priorVariables the stack keeping track of the replaced variables, may be null
774 * @return the length change that occurs, unless priorVariables is null when the int
775 * represents a boolean flag as to whether any change occurred.
776 */
777 private int substitute(final StrBuilder buf, final int offset, final int length, List<String> priorVariables) {
778 final StrMatcher pfxMatcher = getVariablePrefixMatcher();
779 final StrMatcher suffMatcher = getVariableSuffixMatcher();
780 final char escape = getEscapeChar();
781 final StrMatcher valueDelimMatcher = getValueDelimiterMatcher();
782 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
783
784 final boolean top = priorVariables == null;
785 boolean altered = false;
786 int lengthChange = 0;
787 char[] chars = buf.buffer;
788 int bufEnd = offset + length;
789 int pos = offset;
790 while (pos < bufEnd) {
791 final int startMatchLen = pfxMatcher.isMatch(chars, pos, offset,
792 bufEnd);
793 if (startMatchLen == 0) {
794 pos++;
795 } else // found variable start marker
796 if (pos > offset && chars[pos - 1] == escape) {
797 // escaped
798 if (preserveEscapes) {
799 pos++;
800 continue;
801 }
802 buf.deleteCharAt(pos - 1);
803 chars = buf.buffer; // in case buffer was altered
804 lengthChange--;
805 altered = true;
806 bufEnd--;
807 } else {
808 // find suffix
809 final int startPos = pos;
810 pos += startMatchLen;
811 int endMatchLen;
812 int nestedVarCount = 0;
813 while (pos < bufEnd) {
814 if (substitutionInVariablesEnabled
815 && (endMatchLen = pfxMatcher.isMatch(chars,
816 pos, offset, bufEnd)) != 0) {
817 // found a nested variable start
818 nestedVarCount++;
819 pos += endMatchLen;
820 continue;
821 }
822
823 endMatchLen = suffMatcher.isMatch(chars, pos, offset,
824 bufEnd);
825 if (endMatchLen == 0) {
826 pos++;
827 } else {
828 // found variable end marker
829 if (nestedVarCount == 0) {
830 String varNameExpr = new String(chars, startPos
831 + startMatchLen, pos - startPos
832 - startMatchLen);
833 if (substitutionInVariablesEnabled) {
834 final StrBuilder bufName = new StrBuilder(varNameExpr);
835 substitute(bufName, 0, bufName.length());
836 varNameExpr = bufName.toString();
837 }
838 pos += endMatchLen;
839 final int endPos = pos;
840
841 String varName = varNameExpr;
842 String varDefaultValue = null;
843
844 if (valueDelimMatcher != null) {
845 final char [] varNameExprChars = varNameExpr.toCharArray();
846 int valueDelimiterMatchLen;
847 for (int i = 0; i < varNameExprChars.length; i++) {
848 // if there's any nested variable when nested variable substitution disabled, then stop resolving name and default value.
849 if (!substitutionInVariablesEnabled
850 && pfxMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) {
851 break;
852 }
853 if ((valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i)) != 0) {
854 varName = varNameExpr.substring(0, i);
855 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
856 break;
857 }
858 }
859 }
860
861 // on the first call initialize priorVariables
862 if (priorVariables == null) {
863 priorVariables = new ArrayList<>();
864 priorVariables.add(new String(chars,
865 offset, length));
866 }
867
868 // handle cyclic substitution
869 checkCyclicSubstitution(varName, priorVariables);
870 priorVariables.add(varName);
871
872 // resolve the variable
873 String varValue = resolveVariable(varName, buf,
874 startPos, endPos);
875 if (varValue == null) {
876 varValue = varDefaultValue;
877 }
878 if (varValue != null) {
879 // recursive replace
880 final int varLen = varValue.length();
881 buf.replace(startPos, endPos, varValue);
882 altered = true;
883 int change = substitute(buf, startPos,
884 varLen, priorVariables);
885 change = change
886 + varLen - (endPos - startPos);
887 pos += change;
888 bufEnd += change;
889 lengthChange += change;
890 chars = buf.buffer; // in case buffer was
891 // altered
892 }
893
894 // remove variable from the cyclic stack
895 priorVariables
896 .remove(priorVariables.size() - 1);
897 break;
898 }
899 nestedVarCount--;
900 pos += endMatchLen;
901 }
902 }
903 }
904 }
905 if (top) {
906 return altered ? 1 : 0;
907 }
908 return lengthChange;
909 }
910
911 /**
912 * Checks if the specified variable is already in the stack (list) of variables.
913 *
914 * @param varName the variable name to check
915 * @param priorVariables the list of prior variables
916 */
917 private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) {
918 if (!priorVariables.contains(varName)) {
919 return;
920 }
921 final StrBuilder buf = new StrBuilder(256);
922 buf.append("Infinite loop in property interpolation of ");
923 buf.append(priorVariables.remove(0));
924 buf.append(": ");
925 buf.appendWithSeparators(priorVariables, "->");
926 throw new IllegalStateException(buf.toString());
927 }
928
929 /**
930 * Internal method that resolves the value of a variable.
931 * <p>
932 * Most users of this class do not need to call this method. This method is
933 * called automatically by the substitution process.
934 * </p>
935 * <p>
936 * Writers of subclasses can override this method if they need to alter
937 * how each substitution occurs. The method is passed the variable's name
938 * and must return the corresponding value. This implementation uses the
939 * {@link #getVariableResolver()} with the variable's name as the key.
940 * </p>
941 *
942 * @param variableName the name of the variable, not null
943 * @param buf the buffer where the substitution is occurring, not null
944 * @param startPos the start position of the variable including the prefix, valid
945 * @param endPos the end position of the variable including the suffix, valid
946 * @return the variable's value or <b>null</b> if the variable is unknown
947 */
948 protected String resolveVariable(final String variableName, final StrBuilder buf, final int startPos, final int endPos) {
949 final StrLookup<?> resolver = getVariableResolver();
950 if (resolver == null) {
951 return null;
952 }
953 return resolver.lookup(variableName);
954 }
955
956 /**
957 * Returns the escape character.
958 *
959 * @return the character used for escaping variable references
960 */
961 public char getEscapeChar() {
962 return this.escapeChar;
963 }
964
965 /**
966 * Sets the escape character.
967 * If this character is placed before a variable reference in the source
968 * text, this variable will be ignored.
969 *
970 * @param escapeCharacter the escape character (0 for disabling escaping)
971 */
972 public void setEscapeChar(final char escapeCharacter) {
973 this.escapeChar = escapeCharacter;
974 }
975
976 /**
977 * Gets the variable prefix matcher currently in use.
978 * <p>
979 * The variable prefix is the character or characters that identify the
980 * start of a variable. This prefix is expressed in terms of a matcher
981 * allowing advanced prefix matches.
982 * </p>
983 *
984 * @return the prefix matcher in use
985 */
986 public StrMatcher getVariablePrefixMatcher() {
987 return prefixMatcher;
988 }
989
990 /**
991 * Sets the variable prefix matcher currently in use.
992 * <p>
993 * The variable prefix is the character or characters that identify the
994 * start of a variable. This prefix is expressed in terms of a matcher
995 * allowing advanced prefix matches.
996 * </p>
997 *
998 * @param prefixMatcher the prefix matcher to use, null ignored
999 * @return this, to enable chaining
1000 * @throws NullPointerException if the prefix matcher is null
1001 */
1002 public StrSubstitutor setVariablePrefixMatcher(final StrMatcher prefixMatcher) {
1003 this.prefixMatcher = Objects.requireNonNull(prefixMatcher, "prefixMatcher");
1004 return this;
1005 }
1006
1007 /**
1008 * Sets the variable prefix to use.
1009 * <p>
1010 * The variable prefix is the character or characters that identify the
1011 * start of a variable. This method allows a single character prefix to
1012 * be easily set.
1013 * </p>
1014 *
1015 * @param prefix the prefix character to use
1016 * @return this, to enable chaining
1017 */
1018 public StrSubstitutor setVariablePrefix(final char prefix) {
1019 return setVariablePrefixMatcher(StrMatcher.charMatcher(prefix));
1020 }
1021
1022 /**
1023 * Sets the variable prefix to use.
1024 * <p>
1025 * The variable prefix is the character or characters that identify the
1026 * start of a variable. This method allows a string prefix to be easily set.
1027 * </p>
1028 *
1029 * @param prefix the prefix for variables, not null
1030 * @return this, to enable chaining
1031 * @throws NullPointerException if the prefix is null
1032 */
1033 public StrSubstitutor setVariablePrefix(final String prefix) {
1034 return setVariablePrefixMatcher(StrMatcher.stringMatcher(Objects.requireNonNull(prefix)));
1035 }
1036
1037 /**
1038 * Gets the variable suffix matcher currently in use.
1039 * <p>
1040 * The variable suffix is the character or characters that identify the
1041 * end of a variable. This suffix is expressed in terms of a matcher
1042 * allowing advanced suffix matches.
1043 * </p>
1044 *
1045 * @return the suffix matcher in use
1046 */
1047 public StrMatcher getVariableSuffixMatcher() {
1048 return suffixMatcher;
1049 }
1050
1051 /**
1052 * Sets the variable suffix matcher currently in use.
1053 * <p>
1054 * The variable suffix is the character or characters that identify the
1055 * end of a variable. This suffix is expressed in terms of a matcher
1056 * allowing advanced suffix matches.
1057 * </p>
1058 *
1059 * @param suffixMatcher the suffix matcher to use, null ignored
1060 * @return this, to enable chaining
1061 * @throws NullPointerException if the suffix matcher is null
1062 */
1063 public StrSubstitutor setVariableSuffixMatcher(final StrMatcher suffixMatcher) {
1064 this.suffixMatcher = Objects.requireNonNull(suffixMatcher);
1065 return this;
1066 }
1067
1068 /**
1069 * Sets the variable suffix to use.
1070 * <p>
1071 * The variable suffix is the character or characters that identify the
1072 * end of a variable. This method allows a single character suffix to
1073 * be easily set.
1074 * </p>
1075 *
1076 * @param suffix the suffix character to use
1077 * @return this, to enable chaining
1078 */
1079 public StrSubstitutor setVariableSuffix(final char suffix) {
1080 return setVariableSuffixMatcher(StrMatcher.charMatcher(suffix));
1081 }
1082
1083 /**
1084 * Sets the variable suffix to use.
1085 * <p>
1086 * The variable suffix is the character or characters that identify the
1087 * end of a variable. This method allows a string suffix to be easily set.
1088 * </p>
1089 *
1090 * @param suffix the suffix for variables, not null
1091 * @return this, to enable chaining
1092 * @throws NullPointerException if the suffix is null
1093 */
1094 public StrSubstitutor setVariableSuffix(final String suffix) {
1095 return setVariableSuffixMatcher(StrMatcher.stringMatcher(Objects.requireNonNull(suffix)));
1096 }
1097
1098 /**
1099 * Gets the variable default value delimiter matcher currently in use.
1100 * <p>
1101 * The variable default value delimiter is the character or characters that delimit the
1102 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
1103 * allowing advanced variable default value delimiter matches.
1104 * </p>
1105 * <p>
1106 * If it returns null, then the variable default value resolution is disabled.
1107 * </p>
1108 *
1109 * @return the variable default value delimiter matcher in use, may be null
1110 * @since 3.2
1111 */
1112 public StrMatcher getValueDelimiterMatcher() {
1113 return valueDelimiterMatcher;
1114 }
1115
1116 /**
1117 * Sets the variable default value delimiter matcher to use.
1118 * <p>
1119 * The variable default value delimiter is the character or characters that delimit the
1120 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
1121 * allowing advanced variable default value delimiter matches.
1122 * </p>
1123 * <p>
1124 * If the {@code valueDelimiterMatcher} is null, then the variable default value resolution
1125 * becomes disabled.
1126 * </p>
1127 *
1128 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null
1129 * @return this, to enable chaining
1130 * @since 3.2
1131 */
1132 public StrSubstitutor setValueDelimiterMatcher(final StrMatcher valueDelimiterMatcher) {
1133 this.valueDelimiterMatcher = valueDelimiterMatcher;
1134 return this;
1135 }
1136
1137 /**
1138 * Sets the variable default value delimiter to use.
1139 * <p>
1140 * The variable default value delimiter is the character or characters that delimit the
1141 * variable name and the variable default value. This method allows a single character
1142 * variable default value delimiter to be easily set.
1143 * </p>
1144 *
1145 * @param valueDelimiter the variable default value delimiter character to use
1146 * @return this, to enable chaining
1147 * @since 3.2
1148 */
1149 public StrSubstitutor setValueDelimiter(final char valueDelimiter) {
1150 return setValueDelimiterMatcher(StrMatcher.charMatcher(valueDelimiter));
1151 }
1152
1153 /**
1154 * Sets the variable default value delimiter to use.
1155 * <p>
1156 * The variable default value delimiter is the character or characters that delimit the
1157 * variable name and the variable default value. This method allows a string
1158 * variable default value delimiter to be easily set.
1159 * </p>
1160 * <p>
1161 * If the {@code valueDelimiter} is null or empty string, then the variable default
1162 * value resolution becomes disabled.
1163 * </p>
1164 *
1165 * @param valueDelimiter the variable default value delimiter string to use, may be null or empty
1166 * @return this, to enable chaining
1167 * @since 3.2
1168 */
1169 public StrSubstitutor setValueDelimiter(final String valueDelimiter) {
1170 if (StringUtils.isEmpty(valueDelimiter)) {
1171 setValueDelimiterMatcher(null);
1172 return this;
1173 }
1174 return setValueDelimiterMatcher(StrMatcher.stringMatcher(valueDelimiter));
1175 }
1176
1177 /**
1178 * Gets the VariableResolver that is used to lookup variables.
1179 *
1180 * @return the VariableResolver
1181 */
1182 public StrLookup<?> getVariableResolver() {
1183 return this.variableResolver;
1184 }
1185
1186 /**
1187 * Sets the VariableResolver that is used to lookup variables.
1188 *
1189 * @param variableResolver the VariableResolver
1190 */
1191 public void setVariableResolver(final StrLookup<?> variableResolver) {
1192 this.variableResolver = variableResolver;
1193 }
1194
1195 /**
1196 * Returns a flag whether substitution is done in variable names.
1197 *
1198 * @return the substitution in variable names flag
1199 * @since 3.0
1200 */
1201 public boolean isEnableSubstitutionInVariables() {
1202 return enableSubstitutionInVariables;
1203 }
1204
1205 /**
1206 * Sets a flag whether substitution is done in variable names. If set to
1207 * <b>true</b>, the names of variables can contain other variables which are
1208 * processed first before the original variable is evaluated, e.g.
1209 * {@code ${jre-${java.version}}}. The default value is <b>false</b>.
1210 *
1211 * @param enableSubstitutionInVariables the new value of the flag
1212 * @since 3.0
1213 */
1214 public void setEnableSubstitutionInVariables(
1215 final boolean enableSubstitutionInVariables) {
1216 this.enableSubstitutionInVariables = enableSubstitutionInVariables;
1217 }
1218
1219 /**
1220 * Returns the flag controlling whether escapes are preserved during
1221 * substitution.
1222 *
1223 * @return the preserve escape flag
1224 * @since 3.5
1225 */
1226 public boolean isPreserveEscapes() {
1227 return preserveEscapes;
1228 }
1229
1230 /**
1231 * Sets a flag controlling whether escapes are preserved during
1232 * substitution. If set to <b>true</b>, the escape character is retained
1233 * during substitution (e.g. {@code $${this-is-escaped}} remains
1234 * {@code $${this-is-escaped}}). If set to <b>false</b>, the escape
1235 * character is removed during substitution (e.g.
1236 * {@code $${this-is-escaped}} becomes
1237 * {@code ${this-is-escaped}}). The default value is <b>false</b>
1238 *
1239 * @param preserveEscapes true if escapes are to be preserved
1240 * @since 3.5
1241 */
1242 public void setPreserveEscapes(final boolean preserveEscapes) {
1243 this.preserveEscapes = preserveEscapes;
1244 }
1245 }