1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.text;
18
19 import java.util.ArrayList;
20 import java.util.Enumeration;
21 import java.util.HashMap;
22 import java.util.List;
23 import java.util.Map;
24 import java.util.Properties;
25
26 /**
27 * Substitutes variables within a string by values.
28 * <p>
29 * This class takes a piece of text and substitutes all the variables within it.
30 * The default definition of a variable is <code>${variableName}</code>.
31 * The prefix and suffix can be changed via constructors and set methods.
32 * <p>
33 * Variable values are typically resolved from a map, but could also be resolved
34 * from system properties, or by supplying a custom variable resolver.
35 * <p>
36 * The simplest example is to use this class to replace Java System properties. For example:
37 * <pre>
38 * StrSubstitutor.replaceSystemProperties(
39 * "You are running with java.version = ${java.version} and os.name = ${os.name}.");
40 * </pre>
41 * <p>
42 * Typical usage of this class follows the following pattern: First an instance is created
43 * and initialized with the map that contains the values for the available variables.
44 * If a prefix and/or suffix for variables should be used other than the default ones,
45 * the appropriate settings can be performed. After that the <code>replace()</code>
46 * method can be called passing in the source text for interpolation. In the returned
47 * text all variable references (as long as their values are known) will be resolved.
48 * The following example demonstrates this:
49 * <pre>
50 * Map valuesMap = HashMap();
51 * valuesMap.put("animal", "quick brown fox");
52 * valuesMap.put("target", "lazy dog");
53 * String templateString = "The ${animal} jumped over the ${target}.";
54 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
55 * String resolvedString = sub.replace(templateString);
56 * </pre>
57 * yielding:
58 * <pre>
59 * The quick brown fox jumped over the lazy dog.
60 * </pre>
61 * <p>
62 * Also, this class allows to set a default value for unresolved variables.
63 * The default value for a variable can be appended to the variable name after the variable
64 * default value delimiter. The default value of the variable default value delimiter is ':-',
65 * as in bash and other *nix shells, as those are arguably where the default ${} delimiter set originated.
66 * The variable default value delimiter can be manually set by calling {@link #setValueDelimiterMatcher(StrMatcher)},
67 * {@link #setValueDelimiter(char)} or {@link #setValueDelimiter(String)}.
68 * The following shows an example with variable default value settings:
69 * <pre>
70 * Map valuesMap = HashMap();
71 * valuesMap.put("animal", "quick brown fox");
72 * valuesMap.put("target", "lazy dog");
73 * String templateString = "The ${animal} jumped over the ${target}. ${undefined.number:-1234567890}.";
74 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
75 * String resolvedString = sub.replace(templateString);
76 * </pre>
77 * yielding:
78 * <pre>
79 * The quick brown fox jumped over the lazy dog. 1234567890.
80 * </pre>
81 * <p>
82 * In addition to this usage pattern there are some static convenience methods that
83 * cover the most common use cases. These methods can be used without the need of
84 * manually creating an instance. However if multiple replace operations are to be
85 * performed, creating and reusing an instance of this class will be more efficient.
86 * <p>
87 * Variable replacement works in a recursive way. Thus, if a variable value contains
88 * a variable then that variable will also be replaced. Cyclic replacements are
89 * detected and will cause an exception to be thrown.
90 * <p>
91 * Sometimes the interpolation's result must contain a variable prefix. As an example
92 * take the following source text:
93 * <pre>
94 * The variable ${${name}} must be used.
95 * </pre>
96 * Here only the variable's name referred to in the text should be replaced resulting
97 * in the text (assuming that the value of the <code>name</code> variable is <code>x</code>):
98 * <pre>
99 * The variable ${x} must be used.
100 * </pre>
101 * To achieve this effect there are two possibilities: Either set a different prefix
102 * and suffix for variables which do not conflict with the result text you want to
103 * produce. The other possibility is to use the escape character, by default '$'.
104 * If this character is placed before a variable reference, this reference is ignored
105 * and won't be replaced. For example:
106 * <pre>
107 * The variable $${${name}} must be used.
108 * </pre>
109 * <p>
110 * In some complex scenarios you might even want to perform substitution in the
111 * names of variables, for instance
112 * <pre>
113 * ${jre-${java.specification.version}}
114 * </pre>
115 * <code>StrSubstitutor</code> supports this recursive substitution in variable
116 * names, but it has to be enabled explicitly by setting the
117 * {@link #setEnableSubstitutionInVariables(boolean) enableSubstitutionInVariables}
118 * property to <b>true</b>.
119 * <p>This class is <b>not</b> thread safe.</p>
120 *
121 * @since 1.0
122 */
123 public class StrSubstitutor {
124
125 /**
126 * Constant for the default escape character.
127 */
128 public static final char DEFAULT_ESCAPE = '$';
129 /**
130 * Constant for the default variable prefix.
131 */
132 public static final StrMatcher DEFAULT_PREFIX = StrMatcher.stringMatcher("${");
133 /**
134 * Constant for the default variable suffix.
135 */
136 public static final StrMatcher DEFAULT_SUFFIX = StrMatcher.stringMatcher("}");
137 /**
138 * Constant for the default value delimiter of a variable.
139 */
140 public static final StrMatcher DEFAULT_VALUE_DELIMITER = StrMatcher.stringMatcher(":-");
141
142 /**
143 * Stores the escape character.
144 */
145 private char escapeChar;
146 /**
147 * Stores the variable prefix.
148 */
149 private StrMatcher prefixMatcher;
150 /**
151 * Stores the variable suffix.
152 */
153 private StrMatcher suffixMatcher;
154 /**
155 * Stores the default variable value delimiter
156 */
157 private StrMatcher valueDelimiterMatcher;
158 /**
159 * Variable resolution is delegated to an implementor of VariableResolver.
160 */
161 private StrLookup<?> variableResolver;
162 /**
163 * The flag whether substitution in variable names is enabled.
164 */
165 private boolean enableSubstitutionInVariables;
166 /**
167 * Whether escapes should be preserved. Default is false;
168 */
169 private boolean preserveEscapes = false;
170
171 //-----------------------------------------------------------------------
172 /**
173 * Replaces all the occurrences of variables in the given source object with
174 * their matching values from the map.
175 *
176 * @param <V> the type of the values in the map
177 * @param source the source text containing the variables to substitute, null returns null
178 * @param valueMap the map with the values, may be null
179 * @return the result of the replace operation
180 */
181 public static <V> String replace(final Object source, final Map<String, V> valueMap) {
182 return new StrSubstitutor(valueMap).replace(source);
183 }
184
185 /**
186 * Replaces all the occurrences of variables in the given source object with
187 * their matching values from the map. This method allows to specifiy a
188 * custom variable prefix and suffix
189 *
190 * @param <V> the type of the values in the map
191 * @param source the source text containing the variables to substitute, null returns null
192 * @param valueMap the map with the values, may be null
193 * @param prefix the prefix of variables, not null
194 * @param suffix the suffix of variables, not null
195 * @return the result of the replace operation
196 * @throws IllegalArgumentException if the prefix or suffix is null
197 */
198 public static <V> String replace(final Object source, final Map<String, V> valueMap, final String prefix, final String suffix) {
199 return new StrSubstitutor(valueMap, prefix, suffix).replace(source);
200 }
201
202 /**
203 * Replaces all the occurrences of variables in the given source object with their matching
204 * values from the properties.
205 *
206 * @param source the source text containing the variables to substitute, null returns null
207 * @param valueProperties the properties with values, may be null
208 * @return the result of the replace operation
209 */
210 public static String replace(final Object source, final Properties valueProperties) {
211 if (valueProperties == null) {
212 return source.toString();
213 }
214 final Map<String,String> valueMap = new HashMap<>();
215 final Enumeration<?> propNames = valueProperties.propertyNames();
216 while (propNames.hasMoreElements()) {
217 final String propName = (String)propNames.nextElement();
218 final String propValue = valueProperties.getProperty(propName);
219 valueMap.put(propName, propValue);
220 }
221 return StrSubstitutor.replace(source, valueMap);
222 }
223
224 /**
225 * Replaces all the occurrences of variables in the given source object with
226 * their matching values from the system properties.
227 *
228 * @param source the source text containing the variables to substitute, null returns null
229 * @return the result of the replace operation
230 */
231 public static String replaceSystemProperties(final Object source) {
232 return new StrSubstitutor(StrLookup.systemPropertiesLookup()).replace(source);
233 }
234
235 //-----------------------------------------------------------------------
236 /**
237 * Creates a new instance with defaults for variable prefix and suffix
238 * and the escaping character.
239 */
240 public StrSubstitutor() {
241 this((StrLookup<?>) null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
242 }
243
244 /**
245 * Creates a new instance and initializes it. Uses defaults for variable
246 * prefix and suffix and the escaping character.
247 *
248 * @param <V> the type of the values in the map
249 * @param valueMap the map with the variables' values, may be null
250 */
251 public <V> StrSubstitutor(final Map<String, V> valueMap) {
252 this(StrLookup.mapLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
253 }
254
255 /**
256 * Creates a new instance and initializes it. Uses a default escaping character.
257 *
258 * @param <V> the type of the values in the map
259 * @param valueMap the map with the variables' values, may be null
260 * @param prefix the prefix for variables, not null
261 * @param suffix the suffix for variables, not null
262 * @throws IllegalArgumentException if the prefix or suffix is null
263 */
264 public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix) {
265 this(StrLookup.mapLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE);
266 }
267
268 /**
269 * Creates a new instance and initializes it.
270 *
271 * @param <V> the type of the values in the map
272 * @param valueMap the map with the variables' values, may be null
273 * @param prefix the prefix for variables, not null
274 * @param suffix the suffix for variables, not null
275 * @param escape the escape character
276 * @throws IllegalArgumentException if the prefix or suffix is null
277 */
278 public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
279 final char escape) {
280 this(StrLookup.mapLookup(valueMap), prefix, suffix, escape);
281 }
282
283 /**
284 * Creates a new instance and initializes it.
285 *
286 * @param <V> the type of the values in the map
287 * @param valueMap the map with the variables' values, may be null
288 * @param prefix the prefix for variables, not null
289 * @param suffix the suffix for variables, not null
290 * @param escape the escape character
291 * @param valueDelimiter the variable default value delimiter, may be null
292 * @throws IllegalArgumentException if the prefix or suffix is null
293 */
294 public <V> StrSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix,
295 final char escape, final String valueDelimiter) {
296 this(StrLookup.mapLookup(valueMap), prefix, suffix, escape, valueDelimiter);
297 }
298
299 /**
300 * Creates a new instance and initializes it.
301 *
302 * @param variableResolver the variable resolver, may be null
303 */
304 public StrSubstitutor(final StrLookup<?> variableResolver) {
305 this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
306 }
307
308 /**
309 * Creates a new instance and initializes it.
310 *
311 * @param variableResolver the variable resolver, may be null
312 * @param prefix the prefix for variables, not null
313 * @param suffix the suffix for variables, not null
314 * @param escape the escape character
315 * @throws IllegalArgumentException if the prefix or suffix is null
316 */
317 public StrSubstitutor(final StrLookup<?> variableResolver, final String prefix, final String suffix,
318 final char escape) {
319 this.setVariableResolver(variableResolver);
320 this.setVariablePrefix(prefix);
321 this.setVariableSuffix(suffix);
322 this.setEscapeChar(escape);
323 this.setValueDelimiterMatcher(DEFAULT_VALUE_DELIMITER);
324 }
325
326 /**
327 * Creates a new instance and initializes it.
328 *
329 * @param variableResolver the variable resolver, may be null
330 * @param prefix the prefix for variables, not null
331 * @param suffix the suffix for variables, not null
332 * @param escape the escape character
333 * @param valueDelimiter the variable default value delimiter string, may be null
334 * @throws IllegalArgumentException if the prefix or suffix is null
335 */
336 public StrSubstitutor(final StrLookup<?> variableResolver, final String prefix, final String suffix,
337 final char escape, final String valueDelimiter) {
338 this.setVariableResolver(variableResolver);
339 this.setVariablePrefix(prefix);
340 this.setVariableSuffix(suffix);
341 this.setEscapeChar(escape);
342 this.setValueDelimiter(valueDelimiter);
343 }
344
345 /**
346 * Creates a new instance and initializes it.
347 *
348 * @param variableResolver the variable resolver, may be null
349 * @param prefixMatcher the prefix for variables, not null
350 * @param suffixMatcher the suffix for variables, not null
351 * @param escape the escape character
352 * @throws IllegalArgumentException if the prefix or suffix is null
353 */
354 public StrSubstitutor(
355 final StrLookup<?> variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher,
356 final char escape) {
357 this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER);
358 }
359
360 /**
361 * Creates a new instance and initializes it.
362 *
363 * @param variableResolver the variable resolver, may be null
364 * @param prefixMatcher the prefix for variables, not null
365 * @param suffixMatcher the suffix for variables, not null
366 * @param escape the escape character
367 * @param valueDelimiterMatcher the variable default value delimiter matcher, may be null
368 * @throws IllegalArgumentException if the prefix or suffix is null
369 */
370 public StrSubstitutor(
371 final StrLookup<?> variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher,
372 final char escape, final StrMatcher valueDelimiterMatcher) {
373 this.setVariableResolver(variableResolver);
374 this.setVariablePrefixMatcher(prefixMatcher);
375 this.setVariableSuffixMatcher(suffixMatcher);
376 this.setEscapeChar(escape);
377 this.setValueDelimiterMatcher(valueDelimiterMatcher);
378 }
379
380 //-----------------------------------------------------------------------
381 /**
382 * Replaces all the occurrences of variables with their matching values
383 * from the resolver using the given source string as a template.
384 *
385 * @param source the string to replace in, null returns null
386 * @return the result of the replace operation
387 */
388 public String replace(final String source) {
389 if (source == null) {
390 return null;
391 }
392 final StrBuilder buf = new StrBuilder(source);
393 if (substitute(buf, 0, source.length()) == false) {
394 return source;
395 }
396 return buf.toString();
397 }
398
399 /**
400 * Replaces all the occurrences of variables with their matching values
401 * from the resolver using the given source string as a template.
402 * <p>
403 * Only the specified portion of the string will be processed.
404 * The rest of the string is not processed, and is not returned.
405 *
406 * @param source the string to replace in, null returns null
407 * @param offset the start offset within the array, must be valid
408 * @param length the length within the array to be processed, must be valid
409 * @return the result of the replace operation
410 */
411 public String replace(final String source, final int offset, final int length) {
412 if (source == null) {
413 return null;
414 }
415 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
416 if (substitute(buf, 0, length) == false) {
417 return source.substring(offset, offset + length);
418 }
419 return buf.toString();
420 }
421
422 //-----------------------------------------------------------------------
423 /**
424 * Replaces all the occurrences of variables with their matching values
425 * from the resolver using the given source array as a template.
426 * The array is not altered by this method.
427 *
428 * @param source the character array to replace in, not altered, null returns null
429 * @return the result of the replace operation
430 */
431 public String replace(final char[] source) {
432 if (source == null) {
433 return null;
434 }
435 final StrBuilder buf = new StrBuilder(source.length).append(source);
436 substitute(buf, 0, source.length);
437 return buf.toString();
438 }
439
440 /**
441 * Replaces all the occurrences of variables with their matching values
442 * from the resolver using the given source array as a template.
443 * The array is not altered by this method.
444 * <p>
445 * Only the specified portion of the array will be processed.
446 * The rest of the array is not processed, and is not returned.
447 *
448 * @param source the character array to replace in, not altered, null returns null
449 * @param offset the start offset within the array, must be valid
450 * @param length the length within the array to be processed, must be valid
451 * @return the result of the replace operation
452 */
453 public String replace(final char[] source, final int offset, final int length) {
454 if (source == null) {
455 return null;
456 }
457 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
458 substitute(buf, 0, length);
459 return buf.toString();
460 }
461
462 //-----------------------------------------------------------------------
463 /**
464 * Replaces all the occurrences of variables with their matching values
465 * from the resolver using the given source buffer as a template.
466 * The buffer is not altered by this method.
467 *
468 * @param source the buffer to use as a template, not changed, null returns null
469 * @return the result of the replace operation
470 */
471 public String replace(final StringBuffer source) {
472 if (source == null) {
473 return null;
474 }
475 final StrBuilder buf = new StrBuilder(source.length()).append(source);
476 substitute(buf, 0, buf.length());
477 return buf.toString();
478 }
479
480 /**
481 * Replaces all the occurrences of variables with their matching values
482 * from the resolver using the given source buffer as a template.
483 * The buffer is not altered by this method.
484 * <p>
485 * Only the specified portion of the buffer will be processed.
486 * The rest of the buffer is not processed, and is not returned.
487 *
488 * @param source the buffer to use as a template, not changed, null returns null
489 * @param offset the start offset within the array, must be valid
490 * @param length the length within the array to be processed, must be valid
491 * @return the result of the replace operation
492 */
493 public String replace(final StringBuffer source, final int offset, final int length) {
494 if (source == null) {
495 return null;
496 }
497 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
498 substitute(buf, 0, length);
499 return buf.toString();
500 }
501
502 /**
503 * Replaces all the occurrences of variables with their matching values
504 * from the resolver using the given source as a template.
505 * The source is not altered by this method.
506 *
507 * @param source the buffer to use as a template, not changed, null returns null
508 * @return the result of the replace operation
509 */
510 public String replace(final CharSequence source) {
511 if (source == null) {
512 return null;
513 }
514 return replace(source, 0, source.length());
515 }
516
517 /**
518 * Replaces all the occurrences of variables with their matching values
519 * from the resolver using the given source as a template.
520 * The source is not altered by this method.
521 * <p>
522 * Only the specified portion of the buffer will be processed.
523 * The rest of the buffer is not processed, and is not returned.
524 *
525 * @param source the buffer to use as a template, not changed, null returns null
526 * @param offset the start offset within the array, must be valid
527 * @param length the length within the array to be processed, must be valid
528 * @return the result of the replace operation
529 */
530 public String replace(final CharSequence source, final int offset, final int length) {
531 if (source == null) {
532 return null;
533 }
534 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
535 substitute(buf, 0, length);
536 return buf.toString();
537 }
538
539 //-----------------------------------------------------------------------
540 /**
541 * Replaces all the occurrences of variables with their matching values
542 * from the resolver using the given source builder as a template.
543 * The builder is not altered by this method.
544 *
545 * @param source the builder to use as a template, not changed, null returns null
546 * @return the result of the replace operation
547 */
548 public String replace(final StrBuilder source) {
549 if (source == null) {
550 return null;
551 }
552 final StrBuilder buf = new StrBuilder(source.length()).append(source);
553 substitute(buf, 0, buf.length());
554 return buf.toString();
555 }
556
557 /**
558 * Replaces all the occurrences of variables with their matching values
559 * from the resolver using the given source builder as a template.
560 * The builder is not altered by this method.
561 * <p>
562 * Only the specified portion of the builder will be processed.
563 * The rest of the builder is not processed, and is not returned.
564 *
565 * @param source the builder to use as a template, not changed, null returns null
566 * @param offset the start offset within the array, must be valid
567 * @param length the length within the array to be processed, must be valid
568 * @return the result of the replace operation
569 */
570 public String replace(final StrBuilder source, final int offset, final int length) {
571 if (source == null) {
572 return null;
573 }
574 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
575 substitute(buf, 0, length);
576 return buf.toString();
577 }
578
579 //-----------------------------------------------------------------------
580 /**
581 * Replaces all the occurrences of variables in the given source object with
582 * their matching values from the resolver. The input source object is
583 * converted to a string using <code>toString</code> and is not altered.
584 *
585 * @param source the source to replace in, null returns null
586 * @return the result of the replace operation
587 */
588 public String replace(final Object source) {
589 if (source == null) {
590 return null;
591 }
592 final StrBuilder buf = new StrBuilder().append(source);
593 substitute(buf, 0, buf.length());
594 return buf.toString();
595 }
596
597 //-----------------------------------------------------------------------
598 /**
599 * Replaces all the occurrences of variables within the given source buffer
600 * with their matching values from the resolver.
601 * The buffer is updated with the result.
602 *
603 * @param source the buffer to replace in, updated, null returns zero
604 * @return true if altered
605 */
606 public boolean replaceIn(final StringBuffer source) {
607 if (source == null) {
608 return false;
609 }
610 return replaceIn(source, 0, source.length());
611 }
612
613 /**
614 * Replaces all the occurrences of variables within the given source buffer
615 * with their matching values from the resolver.
616 * The buffer is updated with the result.
617 * <p>
618 * Only the specified portion of the buffer will be processed.
619 * The rest of the buffer is not processed, but it is not deleted.
620 *
621 * @param source the buffer to replace in, updated, null returns zero
622 * @param offset the start offset within the array, must be valid
623 * @param length the length within the buffer to be processed, must be valid
624 * @return true if altered
625 */
626 public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
627 if (source == null) {
628 return false;
629 }
630 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
631 if (substitute(buf, 0, length) == false) {
632 return false;
633 }
634 source.replace(offset, offset + length, buf.toString());
635 return true;
636 }
637
638 //-----------------------------------------------------------------------
639 /**
640 * Replaces all the occurrences of variables within the given source buffer
641 * with their matching values from the resolver.
642 * The buffer is updated with the result.
643 *
644 * @param source the buffer to replace in, updated, null returns zero
645 * @return true if altered
646 */
647 public boolean replaceIn(final StringBuilder source) {
648 if (source == null) {
649 return false;
650 }
651 return replaceIn(source, 0, source.length());
652 }
653
654 /**
655 * Replaces all the occurrences of variables within the given source builder
656 * with their matching values from the resolver.
657 * The builder is updated with the result.
658 * <p>
659 * Only the specified portion of the buffer will be processed.
660 * The rest of the buffer is not processed, but it is not deleted.
661 *
662 * @param source the buffer to replace in, updated, null returns zero
663 * @param offset the start offset within the array, must be valid
664 * @param length the length within the buffer to be processed, must be valid
665 * @return true if altered
666 */
667 public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
668 if (source == null) {
669 return false;
670 }
671 final StrBuilder buf = new StrBuilder(length).append(source, offset, length);
672 if (substitute(buf, 0, length) == false) {
673 return false;
674 }
675 source.replace(offset, offset + length, buf.toString());
676 return true;
677 }
678
679 //-----------------------------------------------------------------------
680 /**
681 * Replaces all the occurrences of variables within the given source
682 * builder with their matching values from the resolver.
683 *
684 * @param source the builder to replace in, updated, null returns zero
685 * @return true if altered
686 */
687 public boolean replaceIn(final StrBuilder source) {
688 if (source == null) {
689 return false;
690 }
691 return substitute(source, 0, source.length());
692 }
693
694 /**
695 * Replaces all the occurrences of variables within the given source
696 * builder with their matching values from the resolver.
697 * <p>
698 * Only the specified portion of the builder will be processed.
699 * The rest of the builder is not processed, but it is not deleted.
700 *
701 * @param source the builder to replace in, null returns zero
702 * @param offset the start offset within the array, must be valid
703 * @param length the length within the builder to be processed, must be valid
704 * @return true if altered
705 */
706 public boolean replaceIn(final StrBuilder source, final int offset, final int length) {
707 if (source == null) {
708 return false;
709 }
710 return substitute(source, offset, length);
711 }
712
713 //-----------------------------------------------------------------------
714 /**
715 * Internal method that substitutes the variables.
716 * <p>
717 * Most users of this class do not need to call this method. This method will
718 * be called automatically by another (public) method.
719 * <p>
720 * Writers of subclasses can override this method if they need access to
721 * the substitution process at the start or end.
722 *
723 * @param buf the string builder to substitute into, not null
724 * @param offset the start offset within the builder, must be valid
725 * @param length the length within the builder to be processed, must be valid
726 * @return true if altered
727 */
728 protected boolean substitute(final StrBuilder buf, final int offset, final int length) {
729 return substitute(buf, offset, length, null) > 0;
730 }
731
732 /**
733 * Recursive handler for multiple levels of interpolation. This is the main
734 * interpolation method, which resolves the values of all variable references
735 * contained in the passed in text.
736 *
737 * @param buf the string builder to substitute into, not null
738 * @param offset the start offset within the builder, must be valid
739 * @param length the length within the builder to be processed, must be valid
740 * @param priorVariables the stack keeping track of the replaced variables, may be null
741 * @return the length change that occurs, unless priorVariables is null when the int
742 * represents a boolean flag as to whether any change occurred.
743 */
744 private int substitute(final StrBuilder buf, final int offset, final int length, List<String> priorVariables) {
745 final StrMatcher pfxMatcher = getVariablePrefixMatcher();
746 final StrMatcher suffMatcher = getVariableSuffixMatcher();
747 final char escape = getEscapeChar();
748 final StrMatcher valueDelimMatcher = getValueDelimiterMatcher();
749 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
750
751 final boolean top = priorVariables == null;
752 boolean altered = false;
753 int lengthChange = 0;
754 char[] chars = buf.buffer;
755 int bufEnd = offset + length;
756 int pos = offset;
757 while (pos < bufEnd) {
758 final int startMatchLen = pfxMatcher.isMatch(chars, pos, offset,
759 bufEnd);
760 if (startMatchLen == 0) {
761 pos++;
762 } else {
763 // found variable start marker
764 if (pos > offset && chars[pos - 1] == escape) {
765 // escaped
766 if (preserveEscapes) {
767 pos++;
768 continue;
769 }
770 buf.deleteCharAt(pos - 1);
771 chars = buf.buffer; // in case buffer was altered
772 lengthChange--;
773 altered = true;
774 bufEnd--;
775 } else {
776 // find suffix
777 final int startPos = pos;
778 pos += startMatchLen;
779 int endMatchLen = 0;
780 int nestedVarCount = 0;
781 while (pos < bufEnd) {
782 if (substitutionInVariablesEnabled
783 && (endMatchLen = pfxMatcher.isMatch(chars,
784 pos, offset, bufEnd)) != 0) {
785 // found a nested variable start
786 nestedVarCount++;
787 pos += endMatchLen;
788 continue;
789 }
790
791 endMatchLen = suffMatcher.isMatch(chars, pos, offset,
792 bufEnd);
793 if (endMatchLen == 0) {
794 pos++;
795 } else {
796 // found variable end marker
797 if (nestedVarCount == 0) {
798 String varNameExpr = new String(chars, startPos
799 + startMatchLen, pos - startPos
800 - startMatchLen);
801 if (substitutionInVariablesEnabled) {
802 final StrBuilder bufName = new StrBuilder(varNameExpr);
803 substitute(bufName, 0, bufName.length());
804 varNameExpr = bufName.toString();
805 }
806 pos += endMatchLen;
807 final int endPos = pos;
808
809 String varName = varNameExpr;
810 String varDefaultValue = null;
811
812 if (valueDelimMatcher != null) {
813 final char [] varNameExprChars = varNameExpr.toCharArray();
814 int valueDelimiterMatchLen = 0;
815 for (int i = 0; i < varNameExprChars.length; i++) {
816 // if there's any nested variable when nested variable substitution disabled, then stop resolving name and default value.
817 if (!substitutionInVariablesEnabled
818 && pfxMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) {
819 break;
820 }
821 if ((valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i)) != 0) {
822 varName = varNameExpr.substring(0, i);
823 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
824 break;
825 }
826 }
827 }
828
829 // on the first call initialize priorVariables
830 if (priorVariables == null) {
831 priorVariables = new ArrayList<>();
832 priorVariables.add(new String(chars,
833 offset, length));
834 }
835
836 // handle cyclic substitution
837 checkCyclicSubstitution(varName, priorVariables);
838 priorVariables.add(varName);
839
840 // resolve the variable
841 String varValue = resolveVariable(varName, buf,
842 startPos, endPos);
843 if (varValue == null) {
844 varValue = varDefaultValue;
845 }
846 if (varValue != null) {
847 // recursive replace
848 final int varLen = varValue.length();
849 buf.replace(startPos, endPos, varValue);
850 altered = true;
851 int change = substitute(buf, startPos,
852 varLen, priorVariables);
853 change = change
854 + varLen - (endPos - startPos);
855 pos += change;
856 bufEnd += change;
857 lengthChange += change;
858 chars = buf.buffer; // in case buffer was
859 // altered
860 }
861
862 // remove variable from the cyclic stack
863 priorVariables
864 .remove(priorVariables.size() - 1);
865 break;
866 }
867 nestedVarCount--;
868 pos += endMatchLen;
869 }
870 }
871 }
872 }
873 }
874 if (top) {
875 return altered ? 1 : 0;
876 }
877 return lengthChange;
878 }
879
880 /**
881 * Checks if the specified variable is already in the stack (list) of variables.
882 *
883 * @param varName the variable name to check
884 * @param priorVariables the list of prior variables
885 */
886 private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) {
887 if (priorVariables.contains(varName) == false) {
888 return;
889 }
890 final StrBuilder buf = new StrBuilder(256);
891 buf.append("Infinite loop in property interpolation of ");
892 buf.append(priorVariables.remove(0));
893 buf.append(": ");
894 buf.appendWithSeparators(priorVariables, "->");
895 throw new IllegalStateException(buf.toString());
896 }
897
898 /**
899 * Internal method that resolves the value of a variable.
900 * <p>
901 * Most users of this class do not need to call this method. This method is
902 * called automatically by the substitution process.
903 * <p>
904 * Writers of subclasses can override this method if they need to alter
905 * how each substitution occurs. The method is passed the variable's name
906 * and must return the corresponding value. This implementation uses the
907 * {@link #getVariableResolver()} with the variable's name as the key.
908 *
909 * @param variableName the name of the variable, not null
910 * @param buf the buffer where the substitution is occurring, not null
911 * @param startPos the start position of the variable including the prefix, valid
912 * @param endPos the end position of the variable including the suffix, valid
913 * @return the variable's value or <b>null</b> if the variable is unknown
914 */
915 protected String resolveVariable(final String variableName, final StrBuilder buf, final int startPos, final int endPos) {
916 final StrLookup<?> resolver = getVariableResolver();
917 if (resolver == null) {
918 return null;
919 }
920 return resolver.lookup(variableName);
921 }
922
923 // Escape
924 //-----------------------------------------------------------------------
925 /**
926 * Returns the escape character.
927 *
928 * @return the character used for escaping variable references
929 */
930 public char getEscapeChar() {
931 return this.escapeChar;
932 }
933
934 /**
935 * Sets the escape character.
936 * If this character is placed before a variable reference in the source
937 * text, this variable will be ignored.
938 *
939 * @param escapeCharacter the escape character (0 for disabling escaping)
940 */
941 public void setEscapeChar(final char escapeCharacter) {
942 this.escapeChar = escapeCharacter;
943 }
944
945 // Prefix
946 //-----------------------------------------------------------------------
947 /**
948 * Gets the variable prefix matcher currently in use.
949 * <p>
950 * The variable prefix is the characer or characters that identify the
951 * start of a variable. This prefix is expressed in terms of a matcher
952 * allowing advanced prefix matches.
953 *
954 * @return the prefix matcher in use
955 */
956 public StrMatcher getVariablePrefixMatcher() {
957 return prefixMatcher;
958 }
959
960 /**
961 * Sets the variable prefix matcher currently in use.
962 * <p>
963 * The variable prefix is the characer or characters that identify the
964 * start of a variable. This prefix is expressed in terms of a matcher
965 * allowing advanced prefix matches.
966 *
967 * @param prefixMatcher the prefix matcher to use, null ignored
968 * @return this, to enable chaining
969 * @throws IllegalArgumentException if the prefix matcher is null
970 */
971 public StrSubstitutor setVariablePrefixMatcher(final StrMatcher prefixMatcher) {
972 if (prefixMatcher == null) {
973 throw new IllegalArgumentException("Variable prefix matcher must not be null!");
974 }
975 this.prefixMatcher = prefixMatcher;
976 return this;
977 }
978
979 /**
980 * Sets the variable prefix to use.
981 * <p>
982 * The variable prefix is the character or characters that identify the
983 * start of a variable. This method allows a single character prefix to
984 * be easily set.
985 *
986 * @param prefix the prefix character to use
987 * @return this, to enable chaining
988 */
989 public StrSubstitutor setVariablePrefix(final char prefix) {
990 return setVariablePrefixMatcher(StrMatcher.charMatcher(prefix));
991 }
992
993 /**
994 * Sets the variable prefix to use.
995 * <p>
996 * The variable prefix is the characer or characters that identify the
997 * start of a variable. This method allows a string prefix to be easily set.
998 *
999 * @param prefix the prefix for variables, not null
1000 * @return this, to enable chaining
1001 * @throws IllegalArgumentException if the prefix is null
1002 */
1003 public StrSubstitutor setVariablePrefix(final String prefix) {
1004 if (prefix == null) {
1005 throw new IllegalArgumentException("Variable prefix must not be null!");
1006 }
1007 return setVariablePrefixMatcher(StrMatcher.stringMatcher(prefix));
1008 }
1009
1010 // Suffix
1011 //-----------------------------------------------------------------------
1012 /**
1013 * Gets the variable suffix matcher currently in use.
1014 * <p>
1015 * The variable suffix is the characer or characters that identify the
1016 * end of a variable. This suffix is expressed in terms of a matcher
1017 * allowing advanced suffix matches.
1018 *
1019 * @return the suffix matcher in use
1020 */
1021 public StrMatcher getVariableSuffixMatcher() {
1022 return suffixMatcher;
1023 }
1024
1025 /**
1026 * Sets the variable suffix matcher currently in use.
1027 * <p>
1028 * The variable suffix is the characer or characters that identify the
1029 * end of a variable. This suffix is expressed in terms of a matcher
1030 * allowing advanced suffix matches.
1031 *
1032 * @param suffixMatcher the suffix matcher to use, null ignored
1033 * @return this, to enable chaining
1034 * @throws IllegalArgumentException if the suffix matcher is null
1035 */
1036 public StrSubstitutor setVariableSuffixMatcher(final StrMatcher suffixMatcher) {
1037 if (suffixMatcher == null) {
1038 throw new IllegalArgumentException("Variable suffix matcher must not be null!");
1039 }
1040 this.suffixMatcher = suffixMatcher;
1041 return this;
1042 }
1043
1044 /**
1045 * Sets the variable suffix to use.
1046 * <p>
1047 * The variable suffix is the characer or characters that identify the
1048 * end of a variable. This method allows a single character suffix to
1049 * be easily set.
1050 *
1051 * @param suffix the suffix character to use
1052 * @return this, to enable chaining
1053 */
1054 public StrSubstitutor setVariableSuffix(final char suffix) {
1055 return setVariableSuffixMatcher(StrMatcher.charMatcher(suffix));
1056 }
1057
1058 /**
1059 * Sets the variable suffix to use.
1060 * <p>
1061 * The variable suffix is the character or characters that identify the
1062 * end of a variable. This method allows a string suffix to be easily set.
1063 *
1064 * @param suffix the suffix for variables, not null
1065 * @return this, to enable chaining
1066 * @throws IllegalArgumentException if the suffix is null
1067 */
1068 public StrSubstitutor setVariableSuffix(final String suffix) {
1069 if (suffix == null) {
1070 throw new IllegalArgumentException("Variable suffix must not be null!");
1071 }
1072 return setVariableSuffixMatcher(StrMatcher.stringMatcher(suffix));
1073 }
1074
1075 // Variable Default Value Delimiter
1076 //-----------------------------------------------------------------------
1077 /**
1078 * Gets the variable default value delimiter matcher currently in use.
1079 * <p>
1080 * The variable default value delimiter is the characer or characters that delimite the
1081 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
1082 * allowing advanced variable default value delimiter matches.
1083 * <p>
1084 * If it returns null, then the variable default value resolution is disabled.
1085 *
1086 * @return the variable default value delimiter matcher in use, may be null
1087 */
1088 public StrMatcher getValueDelimiterMatcher() {
1089 return valueDelimiterMatcher;
1090 }
1091
1092 /**
1093 * Sets the variable default value delimiter matcher to use.
1094 * <p>
1095 * The variable default value delimiter is the characer or characters that delimite the
1096 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
1097 * allowing advanced variable default value delimiter matches.
1098 * <p>
1099 * If the <code>valueDelimiterMatcher</code> is null, then the variable default value resolution
1100 * becomes disabled.
1101 *
1102 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null
1103 * @return this, to enable chaining
1104 */
1105 public StrSubstitutor setValueDelimiterMatcher(final StrMatcher valueDelimiterMatcher) {
1106 this.valueDelimiterMatcher = valueDelimiterMatcher;
1107 return this;
1108 }
1109
1110 /**
1111 * Sets the variable default value delimiter to use.
1112 * <p>
1113 * The variable default value delimiter is the characer or characters that delimite the
1114 * variable name and the variable default value. This method allows a single character
1115 * variable default value delimiter to be easily set.
1116 *
1117 * @param valueDelimiter the variable default value delimiter character to use
1118 * @return this, to enable chaining
1119 */
1120 public StrSubstitutor setValueDelimiter(final char valueDelimiter) {
1121 return setValueDelimiterMatcher(StrMatcher.charMatcher(valueDelimiter));
1122 }
1123
1124 /**
1125 * Sets the variable default value delimiter to use.
1126 * <p>
1127 * The variable default value delimiter is the characer or characters that delimite the
1128 * variable name and the variable default value. This method allows a string
1129 * variable default value delimiter to be easily set.
1130 * <p>
1131 * If the <code>valueDelimiter</code> is null or empty string, then the variable default
1132 * value resolution becomes disabled.
1133 *
1134 * @param valueDelimiter the variable default value delimiter string to use, may be null or empty
1135 * @return this, to enable chaining
1136 */
1137 public StrSubstitutor setValueDelimiter(final String valueDelimiter) {
1138 if (valueDelimiter == null || valueDelimiter.length() == 0) {
1139 setValueDelimiterMatcher(null);
1140 return this;
1141 }
1142 return setValueDelimiterMatcher(StrMatcher.stringMatcher(valueDelimiter));
1143 }
1144
1145 // Resolver
1146 //-----------------------------------------------------------------------
1147 /**
1148 * Gets the VariableResolver that is used to lookup variables.
1149 *
1150 * @return the VariableResolver
1151 */
1152 public StrLookup<?> getVariableResolver() {
1153 return this.variableResolver;
1154 }
1155
1156 /**
1157 * Sets the VariableResolver that is used to lookup variables.
1158 *
1159 * @param variableResolver the VariableResolver
1160 */
1161 public void setVariableResolver(final StrLookup<?> variableResolver) {
1162 this.variableResolver = variableResolver;
1163 }
1164
1165 // Substitution support in variable names
1166 //-----------------------------------------------------------------------
1167 /**
1168 * Returns a flag whether substitution is done in variable names.
1169 *
1170 * @return the substitution in variable names flag
1171 */
1172 public boolean isEnableSubstitutionInVariables() {
1173 return enableSubstitutionInVariables;
1174 }
1175
1176 /**
1177 * Sets a flag whether substitution is done in variable names. If set to
1178 * <b>true</b>, the names of variables can contain other variables which are
1179 * processed first before the original variable is evaluated, e.g.
1180 * <code>${jre-${java.version}}</code>. The default value is <b>false</b>.
1181 *
1182 * @param enableSubstitutionInVariables the new value of the flag
1183 */
1184 public void setEnableSubstitutionInVariables(
1185 final boolean enableSubstitutionInVariables) {
1186 this.enableSubstitutionInVariables = enableSubstitutionInVariables;
1187 }
1188
1189 /**
1190 * Returns the flag controlling whether escapes are preserved during
1191 * substitution.
1192 *
1193 * @return the preserve escape flag
1194 */
1195 public boolean isPreserveEscapes() {
1196 return preserveEscapes;
1197 }
1198
1199 /**
1200 * Sets a flag controlling whether escapes are preserved during
1201 * substitution. If set to <b>true</b>, the escape character is retained
1202 * during substitution (e.g. <code>$${this-is-escaped}</code> remains
1203 * <code>$${this-is-escaped}</code>). If set to <b>false</b>, the escape
1204 * character is removed during substitution (e.g.
1205 * <code>$${this-is-escaped}</code> becomes
1206 * <code>${this-is-escaped}</code>). The default value is <b>false</b>
1207 *
1208 * @param preserveEscapes true if escapes are to be preserved
1209 */
1210 public void setPreserveEscapes(final boolean preserveEscapes) {
1211 this.preserveEscapes = preserveEscapes;
1212 }
1213 }