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 * Replaces all the occurrences of variables in the given source object with
171 * their matching values from the map.
172 *
173 * @param <V> the type of the values in the map
174 * @param source the source text containing the variables to substitute, null returns null
175 * @param valueMap the map with the values, may be null
176 * @return the result of the replace operation
177 */
178 public static <V> String replace(final Object source, final Map<String, V> valueMap) {
179 return new StrSubstitutor(valueMap).replace(source);
180 }
181 /**
182 * Replaces all the occurrences of variables in the given source object with
183 * their matching values from the map. This method allows to specify a
184 * custom variable prefix and suffix
185 *
186 * @param <V> the type of the values in the map
187 * @param source the source text containing the variables to substitute, null returns null
188 * @param valueMap the map with the values, may be null
189 * @param prefix the prefix of variables, not null
190 * @param suffix the suffix of variables, not null
191 * @return the result of the replace operation
192 * @throws IllegalArgumentException if the prefix or suffix is null
193 */
194 public static <V> String replace(final Object source, final Map<String, V> valueMap, final String prefix, final String suffix) {
195 return new StrSubstitutor(valueMap, prefix, suffix).replace(source);
196 }
197 /**
198 * Replaces all the occurrences of variables in the given source object with their matching
199 * values from the properties.
200 *
201 * @param source the source text containing the variables to substitute, null returns null
202 * @param valueProperties the properties with values, may be null
203 * @return the result of the replace operation
204 */
205 public static String replace(final Object source, final Properties valueProperties) {
206 if (valueProperties == null) {
207 return source.toString();
208 }
209 final Map<String, String> valueMap = new HashMap<>();
210 final Enumeration<?> propNames = valueProperties.propertyNames();
211 while (propNames.hasMoreElements()) {
212 final String propName = String.valueOf(propNames.nextElement());
213 final String propValue = valueProperties.getProperty(propName);
214 valueMap.put(propName, propValue);
215 }
216 return replace(source, valueMap);
217 }
218 /**
219 * Replaces all the occurrences of variables in the given source object with
220 * their matching values from the system properties.
221 *
222 * @param source the source text containing the variables to substitute, null returns null
223 * @return the result of the replace operation
224 */
225 public static String replaceSystemProperties(final Object source) {
226 return new StrSubstitutor(StrLookup.systemPropertiesLookup()).replace(source);
227 }
228 /**
229 * Stores the escape character.
230 */
231 private char escapeChar;
232 /**
233 * Stores the variable prefix.
234 */
235 private StrMatcher prefixMatcher;
236 /**
237 * Stores the variable suffix.
238 */
239 private StrMatcher suffixMatcher;
240
241 /**
242 * Stores the default variable value delimiter
243 */
244 private StrMatcher valueDelimiterMatcher;
245
246 /**
247 * Variable resolution is delegated to an implementor of VariableResolver.
248 */
249 private StrLookup<?> variableResolver;
250
251 /**
252 * The flag whether substitution in variable names is enabled.
253 */
254 private boolean enableSubstitutionInVariables;
255
256 /**
257 * Whether escapes should be preserved. Default is false;
258 */
259 private boolean preserveEscapes;
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 * Checks if the specified variable is already in the stack (list) of variables.
410 *
411 * @param varName the variable name to check
412 * @param priorVariables the list of prior variables
413 */
414 private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) {
415 if (!priorVariables.contains(varName)) {
416 return;
417 }
418 final StrBuilder buf = new StrBuilder(256);
419 buf.append("Infinite loop in property interpolation of ");
420 buf.append(priorVariables.remove(0));
421 buf.append(": ");
422 buf.appendWithSeparators(priorVariables, "->");
423 throw new IllegalStateException(buf.toString());
424 }
425
426 /**
427 * Returns the escape character.
428 *
429 * @return the character used for escaping variable references
430 */
431 public char getEscapeChar() {
432 return this.escapeChar;
433 }
434
435 /**
436 * Gets the variable default value delimiter matcher currently in use.
437 * <p>
438 * The variable default value delimiter is the character or characters that delimit the
439 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
440 * allowing advanced variable default value delimiter matches.
441 * </p>
442 * <p>
443 * If it returns null, then the variable default value resolution is disabled.
444 * </p>
445 *
446 * @return the variable default value delimiter matcher in use, may be null
447 * @since 3.2
448 */
449 public StrMatcher getValueDelimiterMatcher() {
450 return valueDelimiterMatcher;
451 }
452
453 /**
454 * Gets the variable prefix matcher currently in use.
455 * <p>
456 * The variable prefix is the character or characters that identify the
457 * start of a variable. This prefix is expressed in terms of a matcher
458 * allowing advanced prefix matches.
459 * </p>
460 *
461 * @return the prefix matcher in use
462 */
463 public StrMatcher getVariablePrefixMatcher() {
464 return prefixMatcher;
465 }
466
467 /**
468 * Gets the VariableResolver that is used to lookup variables.
469 *
470 * @return the VariableResolver
471 */
472 public StrLookup<?> getVariableResolver() {
473 return this.variableResolver;
474 }
475
476 /**
477 * Gets the variable suffix matcher currently in use.
478 * <p>
479 * The variable suffix is the character or characters that identify the
480 * end of a variable. This suffix is expressed in terms of a matcher
481 * allowing advanced suffix matches.
482 * </p>
483 *
484 * @return the suffix matcher in use
485 */
486 public StrMatcher getVariableSuffixMatcher() {
487 return suffixMatcher;
488 }
489
490 /**
491 * Returns a flag whether substitution is done in variable names.
492 *
493 * @return the substitution in variable names flag
494 * @since 3.0
495 */
496 public boolean isEnableSubstitutionInVariables() {
497 return enableSubstitutionInVariables;
498 }
499
500 /**
501 * Returns the flag controlling whether escapes are preserved during
502 * substitution.
503 *
504 * @return the preserve escape flag
505 * @since 3.5
506 */
507 public boolean isPreserveEscapes() {
508 return preserveEscapes;
509 }
510
511 /**
512 * Replaces all the occurrences of variables with their matching values
513 * from the resolver using the given source array as a template.
514 * The array is not altered by this method.
515 *
516 * @param source the character array to replace in, not altered, null returns null
517 * @return the result of the replace operation
518 */
519 public String replace(final char[] source) {
520 if (source == null) {
521 return null;
522 }
523 final StrBuilder buf = new StrBuilder(source.length).append(source);
524 substitute(buf, 0, source.length);
525 return buf.toString();
526 }
527
528 /**
529 * Replaces all the occurrences of variables with their matching values
530 * from the resolver using the given source array as a template.
531 * The array is not altered by this method.
532 * <p>
533 * Only the specified portion of the array will be processed.
534 * The rest of the array is not processed, and is not returned.
535 * </p>
536 *
537 * @param source the character array to replace in, not altered, null returns null
538 * @param offset the start offset within the array, must be valid
539 * @param length the length within the array to be processed, must be valid
540 * @return the result of the replace operation
541 */
542 public String replace(final char[] source, final int offset, final int length) {
543 if (source == null) {
544 return null;
545 }
546 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
547 substitute(buf, 0, length);
548 return buf.toString();
549 }
550
551 /**
552 * Replaces all the occurrences of variables with their matching values
553 * from the resolver using the given source as a template.
554 * The source is not altered by this method.
555 *
556 * @param source the buffer to use as a template, not changed, null returns null
557 * @return the result of the replace operation
558 * @since 3.2
559 */
560 public String replace(final CharSequence source) {
561 if (source == null) {
562 return null;
563 }
564 return replace(source, 0, source.length());
565 }
566
567 /**
568 * Replaces all the occurrences of variables with their matching values
569 * from the resolver using the given source as a template.
570 * The source is not altered by this method.
571 * <p>
572 * Only the specified portion of the buffer will be processed.
573 * The rest of the buffer is not processed, and is not returned.
574 * </p>
575 *
576 * @param source the buffer to use as a template, not changed, null returns null
577 * @param offset the start offset within the array, must be valid
578 * @param length the length within the array to be processed, must be valid
579 * @return the result of the replace operation
580 * @since 3.2
581 */
582 public String replace(final CharSequence source, final int offset, final int length) {
583 if (source == null) {
584 return null;
585 }
586 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
587 substitute(buf, 0, length);
588 return buf.toString();
589 }
590
591 /**
592 * Replaces all the occurrences of variables in the given source object with
593 * their matching values from the resolver. The input source object is
594 * converted to a string using {@code toString} and is not altered.
595 *
596 * @param source the source to replace in, null returns null
597 * @return the result of the replace operation
598 */
599 public String replace(final Object source) {
600 if (source == null) {
601 return null;
602 }
603 final StrBuilder buf = new StrBuilder().append(source);
604 substitute(buf, 0, buf.length());
605 return buf.toString();
606 }
607
608 /**
609 * Replaces all the occurrences of variables with their matching values
610 * from the resolver using the given source builder as a template.
611 * The builder is not altered by this method.
612 *
613 * @param source the builder to use as a template, not changed, null returns null
614 * @return the result of the replace operation
615 */
616 public String replace(final StrBuilder source) {
617 if (source == null) {
618 return null;
619 }
620 final StrBuilder buf = new StrBuilder(source.length()).append(source);
621 substitute(buf, 0, buf.length());
622 return buf.toString();
623 }
624
625 /**
626 * Replaces all the occurrences of variables with their matching values
627 * from the resolver using the given source builder as a template.
628 * The builder is not altered by this method.
629 * <p>
630 * Only the specified portion of the builder will be processed.
631 * The rest of the builder is not processed, and is not returned.
632 * </p>
633 *
634 * @param source the builder to use as a template, not changed, null returns null
635 * @param offset the start offset within the array, must be valid
636 * @param length the length within the array to be processed, must be valid
637 * @return the result of the replace operation
638 */
639 public String replace(final StrBuilder source, final int offset, final int length) {
640 if (source == null) {
641 return null;
642 }
643 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
644 substitute(buf, 0, length);
645 return buf.toString();
646 }
647
648 /**
649 * Replaces all the occurrences of variables with their matching values
650 * from the resolver using the given source string as a template.
651 *
652 * @param source the string to replace in, null returns null
653 * @return the result of the replace operation
654 */
655 public String replace(final String source) {
656 if (source == null) {
657 return null;
658 }
659 final StrBuilder buf = new StrBuilder(source);
660 if (!substitute(buf, 0, source.length())) {
661 return source;
662 }
663 return buf.toString();
664 }
665
666 /**
667 * Replaces all the occurrences of variables with their matching values
668 * from the resolver using the given source string as a template.
669 * <p>
670 * Only the specified portion of the string will be processed.
671 * The rest of the string is not processed, and is not returned.
672 * </p>
673 *
674 * @param source the string to replace in, null returns null
675 * @param offset the start offset within the array, must be valid
676 * @param length the length within the array to be processed, must be valid
677 * @return the result of the replace operation
678 */
679 public String replace(final String source, final int offset, final int length) {
680 if (source == null) {
681 return null;
682 }
683 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
684 if (!substitute(buf, 0, length)) {
685 return source.substring(offset, offset + length);
686 }
687 return buf.toString();
688 }
689
690 /**
691 * Replaces all the occurrences of variables with their matching values
692 * from the resolver using the given source buffer as a template.
693 * The buffer is not altered by this method.
694 *
695 * @param source the buffer to use as a template, not changed, null returns null
696 * @return the result of the replace operation
697 */
698 public String replace(final StringBuffer source) {
699 if (source == null) {
700 return null;
701 }
702 final StrBuilder buf = new StrBuilder(source.length()).append(source);
703 substitute(buf, 0, buf.length());
704 return buf.toString();
705 }
706
707 /**
708 * Replaces all the occurrences of variables with their matching values
709 * from the resolver using the given source buffer as a template.
710 * The buffer is not altered by this method.
711 * <p>
712 * Only the specified portion of the buffer will be processed.
713 * The rest of the buffer is not processed, and is not returned.
714 * </p>
715 *
716 * @param source the buffer to use as a template, not changed, null returns null
717 * @param offset the start offset within the array, must be valid
718 * @param length the length within the array to be processed, must be valid
719 * @return the result of the replace operation
720 */
721 public String replace(final StringBuffer source, final int offset, final int length) {
722 if (source == null) {
723 return null;
724 }
725 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
726 substitute(buf, 0, length);
727 return buf.toString();
728 }
729
730 /**
731 * Replaces all the occurrences of variables within the given source
732 * builder with their matching values from the resolver.
733 *
734 * @param source the builder to replace in, updated, null returns zero
735 * @return true if altered
736 */
737 public boolean replaceIn(final StrBuilder source) {
738 if (source == null) {
739 return false;
740 }
741 return substitute(source, 0, source.length());
742 }
743
744 /**
745 * Replaces all the occurrences of variables within the given source
746 * builder with their matching values from the resolver.
747 * <p>
748 * Only the specified portion of the builder will be processed.
749 * The rest of the builder is not processed, but it is not deleted.
750 * </p>
751 *
752 * @param source the builder to replace in, null returns zero
753 * @param offset the start offset within the array, must be valid
754 * @param length the length within the builder to be processed, must be valid
755 * @return true if altered
756 */
757 public boolean replaceIn(final StrBuilder source, final int offset, final int length) {
758 if (source == null) {
759 return false;
760 }
761 return substitute(source, offset, length);
762 }
763
764 /**
765 * Replaces all the occurrences of variables within the given source buffer
766 * with their matching values from the resolver.
767 * The buffer is updated with the result.
768 *
769 * @param source the buffer to replace in, updated, null returns zero
770 * @return true if altered
771 */
772 public boolean replaceIn(final StringBuffer source) {
773 if (source == null) {
774 return false;
775 }
776 return replaceIn(source, 0, source.length());
777 }
778
779 /**
780 * Replaces all the occurrences of variables within the given source buffer
781 * with their matching values from the resolver.
782 * The buffer is updated with the result.
783 * <p>
784 * Only the specified portion of the buffer will be processed.
785 * The rest of the buffer is not processed, but it is not deleted.
786 * </p>
787 *
788 * @param source the buffer to replace in, updated, null returns zero
789 * @param offset the start offset within the array, must be valid
790 * @param length the length within the buffer to be processed, must be valid
791 * @return true if altered
792 */
793 public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
794 if (source == null) {
795 return false;
796 }
797 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
798 if (!substitute(buf, 0, length)) {
799 return false;
800 }
801 source.replace(offset, offset + length, buf.toString());
802 return true;
803 }
804
805 /**
806 * Replaces all the occurrences of variables within the given source buffer
807 * with their matching values from the resolver.
808 * The buffer is updated with the result.
809 *
810 * @param source the buffer to replace in, updated, null returns zero
811 * @return true if altered
812 * @since 3.2
813 */
814 public boolean replaceIn(final StringBuilder source) {
815 if (source == null) {
816 return false;
817 }
818 return replaceIn(source, 0, source.length());
819 }
820
821 /**
822 * Replaces all the occurrences of variables within the given source builder
823 * with their matching values from the resolver.
824 * The builder is updated with the result.
825 * <p>
826 * Only the specified portion of the buffer will be processed.
827 * The rest of the buffer is not processed, but it is not deleted.
828 * </p>
829 *
830 * @param source the buffer to replace in, updated, null returns zero
831 * @param offset the start offset within the array, must be valid
832 * @param length the length within the buffer to be processed, must be valid
833 * @return true if altered
834 * @since 3.2
835 */
836 public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
837 if (source == null) {
838 return false;
839 }
840 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
841 if (!substitute(buf, 0, length)) {
842 return false;
843 }
844 source.replace(offset, offset + length, buf.toString());
845 return true;
846 }
847
848 /**
849 * Internal method that resolves the value of a variable.
850 * <p>
851 * Most users of this class do not need to call this method. This method is
852 * called automatically by the substitution process.
853 * </p>
854 * <p>
855 * Writers of subclasses can override this method if they need to alter
856 * how each substitution occurs. The method is passed the variable's name
857 * and must return the corresponding value. This implementation uses the
858 * {@link #getVariableResolver()} with the variable's name as the key.
859 * </p>
860 *
861 * @param variableName the name of the variable, not null
862 * @param buf the buffer where the substitution is occurring, not null
863 * @param startPos the start position of the variable including the prefix, valid
864 * @param endPos the end position of the variable including the suffix, valid
865 * @return the variable's value or <b>null</b> if the variable is unknown
866 */
867 protected String resolveVariable(final String variableName, final StrBuilder buf, final int startPos, final int endPos) {
868 final StrLookup<?> resolver = getVariableResolver();
869 if (resolver == null) {
870 return null;
871 }
872 return resolver.lookup(variableName);
873 }
874
875 /**
876 * Sets a flag whether substitution is done in variable names. If set to
877 * <b>true</b>, the names of variables can contain other variables which are
878 * processed first before the original variable is evaluated, e.g.
879 * {@code ${jre-${java.version}}}. The default value is <b>false</b>.
880 *
881 * @param enableSubstitutionInVariables the new value of the flag
882 * @since 3.0
883 */
884 public void setEnableSubstitutionInVariables(
885 final boolean enableSubstitutionInVariables) {
886 this.enableSubstitutionInVariables = enableSubstitutionInVariables;
887 }
888
889 /**
890 * Sets the escape character.
891 * If this character is placed before a variable reference in the source
892 * text, this variable will be ignored.
893 *
894 * @param escapeCharacter the escape character (0 for disabling escaping)
895 */
896 public void setEscapeChar(final char escapeCharacter) {
897 this.escapeChar = escapeCharacter;
898 }
899
900 /**
901 * Sets a flag controlling whether escapes are preserved during
902 * substitution. If set to <b>true</b>, the escape character is retained
903 * during substitution (e.g. {@code $${this-is-escaped}} remains
904 * {@code $${this-is-escaped}}). If set to <b>false</b>, the escape
905 * character is removed during substitution (e.g.
906 * {@code $${this-is-escaped}} becomes
907 * {@code ${this-is-escaped}}). The default value is <b>false</b>
908 *
909 * @param preserveEscapes true if escapes are to be preserved
910 * @since 3.5
911 */
912 public void setPreserveEscapes(final boolean preserveEscapes) {
913 this.preserveEscapes = preserveEscapes;
914 }
915
916 /**
917 * Sets the variable default value delimiter to use.
918 * <p>
919 * The variable default value delimiter is the character or characters that delimit the
920 * variable name and the variable default value. This method allows a single character
921 * variable default value delimiter to be easily set.
922 * </p>
923 *
924 * @param valueDelimiter the variable default value delimiter character to use
925 * @return this, to enable chaining
926 * @since 3.2
927 */
928 public StrSubstitutor setValueDelimiter(final char valueDelimiter) {
929 return setValueDelimiterMatcher(StrMatcher.charMatcher(valueDelimiter));
930 }
931
932 /**
933 * Sets the variable default value delimiter to use.
934 * <p>
935 * The variable default value delimiter is the character or characters that delimit the
936 * variable name and the variable default value. This method allows a string
937 * variable default value delimiter to be easily set.
938 * </p>
939 * <p>
940 * If the {@code valueDelimiter} is null or empty string, then the variable default
941 * value resolution becomes disabled.
942 * </p>
943 *
944 * @param valueDelimiter the variable default value delimiter string to use, may be null or empty
945 * @return this, to enable chaining
946 * @since 3.2
947 */
948 public StrSubstitutor setValueDelimiter(final String valueDelimiter) {
949 if (StringUtils.isEmpty(valueDelimiter)) {
950 setValueDelimiterMatcher(null);
951 return this;
952 }
953 return setValueDelimiterMatcher(StrMatcher.stringMatcher(valueDelimiter));
954 }
955
956 /**
957 * Sets the variable default value delimiter matcher to use.
958 * <p>
959 * The variable default value delimiter is the character or characters that delimit the
960 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
961 * allowing advanced variable default value delimiter matches.
962 * </p>
963 * <p>
964 * If the {@code valueDelimiterMatcher} is null, then the variable default value resolution
965 * becomes disabled.
966 * </p>
967 *
968 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null
969 * @return this, to enable chaining
970 * @since 3.2
971 */
972 public StrSubstitutor setValueDelimiterMatcher(final StrMatcher valueDelimiterMatcher) {
973 this.valueDelimiterMatcher = valueDelimiterMatcher;
974 return this;
975 }
976
977 /**
978 * Sets the variable prefix to use.
979 * <p>
980 * The variable prefix is the character or characters that identify the
981 * start of a variable. This method allows a single character prefix to
982 * be easily set.
983 * </p>
984 *
985 * @param prefix the prefix character to use
986 * @return this, to enable chaining
987 */
988 public StrSubstitutor setVariablePrefix(final char prefix) {
989 return setVariablePrefixMatcher(StrMatcher.charMatcher(prefix));
990 }
991
992 /**
993 * Sets the variable prefix to use.
994 * <p>
995 * The variable prefix is the character or characters that identify the
996 * start of a variable. This method allows a string prefix to be easily set.
997 * </p>
998 *
999 * @param prefix the prefix for variables, not null
1000 * @return this, to enable chaining
1001 * @throws NullPointerException if the prefix is null
1002 */
1003 public StrSubstitutor setVariablePrefix(final String prefix) {
1004 return setVariablePrefixMatcher(StrMatcher.stringMatcher(Objects.requireNonNull(prefix)));
1005 }
1006
1007 /**
1008 * Sets the variable prefix matcher currently in use.
1009 * <p>
1010 * The variable prefix is the character or characters that identify the
1011 * start of a variable. This prefix is expressed in terms of a matcher
1012 * allowing advanced prefix matches.
1013 * </p>
1014 *
1015 * @param prefixMatcher the prefix matcher to use, null ignored
1016 * @return this, to enable chaining
1017 * @throws NullPointerException if the prefix matcher is null
1018 */
1019 public StrSubstitutor setVariablePrefixMatcher(final StrMatcher prefixMatcher) {
1020 this.prefixMatcher = Objects.requireNonNull(prefixMatcher, "prefixMatcher");
1021 return this;
1022 }
1023
1024 /**
1025 * Sets the VariableResolver that is used to lookup variables.
1026 *
1027 * @param variableResolver the VariableResolver
1028 */
1029 public void setVariableResolver(final StrLookup<?> variableResolver) {
1030 this.variableResolver = variableResolver;
1031 }
1032
1033 /**
1034 * Sets the variable suffix to use.
1035 * <p>
1036 * The variable suffix is the character or characters that identify the
1037 * end of a variable. This method allows a single character suffix to
1038 * be easily set.
1039 * </p>
1040 *
1041 * @param suffix the suffix character to use
1042 * @return this, to enable chaining
1043 */
1044 public StrSubstitutor setVariableSuffix(final char suffix) {
1045 return setVariableSuffixMatcher(StrMatcher.charMatcher(suffix));
1046 }
1047
1048 /**
1049 * Sets the variable suffix to use.
1050 * <p>
1051 * The variable suffix is the character or characters that identify the
1052 * end of a variable. This method allows a string suffix to be easily set.
1053 * </p>
1054 *
1055 * @param suffix the suffix for variables, not null
1056 * @return this, to enable chaining
1057 * @throws NullPointerException if the suffix is null
1058 */
1059 public StrSubstitutor setVariableSuffix(final String suffix) {
1060 return setVariableSuffixMatcher(StrMatcher.stringMatcher(Objects.requireNonNull(suffix)));
1061 }
1062
1063 /**
1064 * Sets the variable suffix matcher currently in use.
1065 * <p>
1066 * The variable suffix is the character or characters that identify the
1067 * end of a variable. This suffix is expressed in terms of a matcher
1068 * allowing advanced suffix matches.
1069 * </p>
1070 *
1071 * @param suffixMatcher the suffix matcher to use, null ignored
1072 * @return this, to enable chaining
1073 * @throws NullPointerException if the suffix matcher is null
1074 */
1075 public StrSubstitutor setVariableSuffixMatcher(final StrMatcher suffixMatcher) {
1076 this.suffixMatcher = Objects.requireNonNull(suffixMatcher);
1077 return this;
1078 }
1079
1080 /**
1081 * Internal method that substitutes the variables.
1082 * <p>
1083 * Most users of this class do not need to call this method. This method will
1084 * be called automatically by another (public) method.
1085 * </p>
1086 * <p>
1087 * Writers of subclasses can override this method if they need access to
1088 * the substitution process at the start or end.
1089 * </p>
1090 *
1091 * @param buf the string builder to substitute into, not null
1092 * @param offset the start offset within the builder, must be valid
1093 * @param length the length within the builder to be processed, must be valid
1094 * @return true if altered
1095 */
1096 protected boolean substitute(final StrBuilder buf, final int offset, final int length) {
1097 return substitute(buf, offset, length, null) > 0;
1098 }
1099
1100 /**
1101 * Recursive handler for multiple levels of interpolation. This is the main
1102 * interpolation method, which resolves the values of all variable references
1103 * contained in the passed-in text.
1104 *
1105 * @param buf the string builder to substitute into, not null
1106 * @param offset the start offset within the builder, must be valid
1107 * @param length the length within the builder to be processed, must be valid
1108 * @param priorVariables the stack keeping track of the replaced variables, may be null
1109 * @return the length change that occurs, unless priorVariables is null when the int
1110 * represents a boolean flag as to whether any change occurred.
1111 */
1112 private int substitute(final StrBuilder buf, final int offset, final int length, List<String> priorVariables) {
1113 final StrMatcher pfxMatcher = getVariablePrefixMatcher();
1114 final StrMatcher suffMatcher = getVariableSuffixMatcher();
1115 final char escape = getEscapeChar();
1116 final StrMatcher valueDelimMatcher = getValueDelimiterMatcher();
1117 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
1118
1119 final boolean top = priorVariables == null;
1120 boolean altered = false;
1121 int lengthChange = 0;
1122 char[] chars = buf.buffer;
1123 int bufEnd = offset + length;
1124 int pos = offset;
1125 while (pos < bufEnd) {
1126 final int startMatchLen = pfxMatcher.isMatch(chars, pos, offset,
1127 bufEnd);
1128 if (startMatchLen == 0) {
1129 pos++;
1130 } else // found variable start marker
1131 if (pos > offset && chars[pos - 1] == escape) {
1132 // escaped
1133 if (preserveEscapes) {
1134 pos++;
1135 continue;
1136 }
1137 buf.deleteCharAt(pos - 1);
1138 chars = buf.buffer; // in case buffer was altered
1139 lengthChange--;
1140 altered = true;
1141 bufEnd--;
1142 } else {
1143 // find suffix
1144 final int startPos = pos;
1145 pos += startMatchLen;
1146 int endMatchLen;
1147 int nestedVarCount = 0;
1148 while (pos < bufEnd) {
1149 if (substitutionInVariablesEnabled
1150 && (endMatchLen = pfxMatcher.isMatch(chars,
1151 pos, offset, bufEnd)) != 0) {
1152 // found a nested variable start
1153 nestedVarCount++;
1154 pos += endMatchLen;
1155 continue;
1156 }
1157
1158 endMatchLen = suffMatcher.isMatch(chars, pos, offset,
1159 bufEnd);
1160 if (endMatchLen == 0) {
1161 pos++;
1162 } else {
1163 // found variable end marker
1164 if (nestedVarCount == 0) {
1165 String varNameExpr = new String(chars, startPos
1166 + startMatchLen, pos - startPos
1167 - startMatchLen);
1168 if (substitutionInVariablesEnabled) {
1169 final StrBuilder bufName = new StrBuilder(varNameExpr);
1170 substitute(bufName, 0, bufName.length());
1171 varNameExpr = bufName.toString();
1172 }
1173 pos += endMatchLen;
1174 final int endPos = pos;
1175
1176 String varName = varNameExpr;
1177 String varDefaultValue = null;
1178
1179 if (valueDelimMatcher != null) {
1180 final char [] varNameExprChars = varNameExpr.toCharArray();
1181 int valueDelimiterMatchLen;
1182 for (int i = 0; i < varNameExprChars.length; i++) {
1183 // if there's any nested variable when nested variable substitution disabled, then stop resolving name and default value.
1184 if (!substitutionInVariablesEnabled
1185 && pfxMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) {
1186 break;
1187 }
1188 if ((valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i)) != 0) {
1189 varName = varNameExpr.substring(0, i);
1190 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
1191 break;
1192 }
1193 }
1194 }
1195
1196 // on the first call initialize priorVariables
1197 if (priorVariables == null) {
1198 priorVariables = new ArrayList<>();
1199 priorVariables.add(new String(chars,
1200 offset, length));
1201 }
1202
1203 // handle cyclic substitution
1204 checkCyclicSubstitution(varName, priorVariables);
1205 priorVariables.add(varName);
1206
1207 // resolve the variable
1208 String varValue = resolveVariable(varName, buf,
1209 startPos, endPos);
1210 if (varValue == null) {
1211 varValue = varDefaultValue;
1212 }
1213 if (varValue != null) {
1214 // recursive replace
1215 final int varLen = varValue.length();
1216 buf.replace(startPos, endPos, varValue);
1217 altered = true;
1218 int change = substitute(buf, startPos,
1219 varLen, priorVariables);
1220 change = change
1221 + varLen - (endPos - startPos);
1222 pos += change;
1223 bufEnd += change;
1224 lengthChange += change;
1225 chars = buf.buffer; // in case buffer was
1226 // altered
1227 }
1228
1229 // remove variable from the cyclic stack
1230 priorVariables
1231 .remove(priorVariables.size() - 1);
1232 break;
1233 }
1234 nestedVarCount--;
1235 pos += endMatchLen;
1236 }
1237 }
1238 }
1239 }
1240 if (top) {
1241 return altered ? 1 : 0;
1242 }
1243 return lengthChange;
1244 }
1245 }