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.logging.log4j.core.lookup;
18
19 import java.util.ArrayList;
20 import java.util.Enumeration;
21 import java.util.HashMap;
22 import java.util.Iterator;
23 import java.util.List;
24 import java.util.Map;
25 import java.util.Properties;
26
27 import org.apache.logging.log4j.core.LogEvent;
28 import org.apache.logging.log4j.util.Strings;
29
30 /**
31 * Substitutes variables within a string by values.
32 * <p>
33 * This class takes a piece of text and substitutes all the variables within it.
34 * The default definition of a variable is <code>${variableName}</code>.
35 * The prefix and suffix can be changed via constructors and set methods.
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 * The simplest example is to use this class to replace Java System properties. For example:
41 * <pre>
42 * StrSubstitutor.replaceSystemProperties(
43 * "You are running with java.version = ${java.version} and os.name = ${os.name}.");
44 * </pre>
45 * <p>
46 * Typical usage of this class follows the following pattern: First an instance is created
47 * and initialized with the map that contains the values for the available variables.
48 * If a prefix and/or suffix for variables should be used other than the default ones,
49 * the appropriate settings can be performed. After that the <code>replace()</code>
50 * method can be called passing in the source text for interpolation. In the returned
51 * text all variable references (as long as their values are known) will be resolved.
52 * The following example demonstrates this:
53 * <pre>
54 * Map valuesMap = HashMap();
55 * valuesMap.put("animal", "quick brown fox");
56 * valuesMap.put("target", "lazy dog");
57 * String templateString = "The ${animal} jumped over the ${target}.";
58 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
59 * String resolvedString = sub.replace(templateString);
60 * </pre>
61 * yielding:
62 * <pre>
63 * The quick brown fox jumped over the lazy dog.
64 * </pre>
65 * <p>
66 * Also, this class allows to set a default value for unresolved variables.
67 * The default value for a variable can be appended to the variable name after the variable
68 * default value delimiter. The default value of the variable default value delimiter is ':-',
69 * as in bash and other *nix shells, as those are arguably where the default ${} delimiter set originated.
70 * The variable default value delimiter can be manually set by calling {@link #setValueDelimiterMatcher(StrMatcher)},
71 * {@link #setValueDelimiter(char)} or {@link #setValueDelimiter(String)}.
72 * The following shows an example with varialbe default value settings:
73 * <pre>
74 * Map valuesMap = HashMap();
75 * valuesMap.put("animal", "quick brown fox");
76 * valuesMap.put("target", "lazy dog");
77 * String templateString = "The ${animal} jumped over the ${target}. ${undefined.number:-1234567890}.";
78 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
79 * String resolvedString = sub.replace(templateString);
80 * </pre>
81 * yielding:
82 * <pre>
83 * The quick brown fox jumped over the lazy dog. 1234567890.
84 * </pre>
85 * <p>
86 * In addition to this usage pattern there are some static convenience methods that
87 * cover the most common use cases. These methods can be used without the need of
88 * manually creating an instance. However if multiple replace operations are to be
89 * performed, creating and reusing an instance of this class will be more efficient.
90 * <p>
91 * Variable replacement works in a recursive way. Thus, if a variable value contains
92 * a variable then that variable will also be replaced. Cyclic replacements are
93 * detected and will cause an exception to be thrown.
94 * <p>
95 * Sometimes the interpolation's result must contain a variable prefix. As an example
96 * take the following source text:
97 * <pre>
98 * The variable ${${name}} must be used.
99 * </pre>
100 * Here only the variable's name referred to in the text should be replaced resulting
101 * in the text (assuming that the value of the <code>name</code> variable is <code>x</code>):
102 * <pre>
103 * The variable ${x} must be used.
104 * </pre>
105 * To achieve this effect there are two possibilities: Either set a different prefix
106 * and suffix for variables which do not conflict with the result text you want to
107 * produce. The other possibility is to use the escape character, by default '$'.
108 * If this character is placed before a variable reference, this reference is ignored
109 * and won't be replaced. For example:
110 * <pre>
111 * The variable $${${name}} must be used.
112 * </pre>
113 * <p>
114 * In some complex scenarios you might even want to perform substitution in the
115 * names of variables, for instance
116 * <pre>
117 * ${jre-${java.specification.version}}
118 * </pre>
119 * <code>StrSubstitutor</code> supports this recursive substitution in variable
120 * names, but it has to be enabled explicitly by setting the
121 * {@link #setEnableSubstitutionInVariables(boolean) enableSubstitutionInVariables}
122 * property to <b>true</b>.
123 *
124 */
125 public class StrSubstitutor {
126
127 /**
128 * Constant for the default escape character.
129 */
130 public static final char DEFAULT_ESCAPE = '$';
131 /**
132 * Constant for the default variable prefix.
133 */
134 public static final StrMatcher DEFAULT_PREFIX = StrMatcher.stringMatcher("${");
135 /**
136 * Constant for the default variable suffix.
137 */
138 public static final StrMatcher DEFAULT_SUFFIX = StrMatcher.stringMatcher("}");
139 /**
140 * Constant for the default value delimiter of a variable.
141 */
142 public static final StrMatcher DEFAULT_VALUE_DELIMITER = StrMatcher.stringMatcher(":-");
143
144 private static final int BUF_SIZE = 256;
145
146 /**
147 * Stores the escape character.
148 */
149 private char escapeChar;
150 /**
151 * Stores the variable prefix.
152 */
153 private StrMatcher prefixMatcher;
154 /**
155 * Stores the variable suffix.
156 */
157 private StrMatcher suffixMatcher;
158 /**
159 * Stores the default variable value delimiter
160 */
161 private StrMatcher valueDelimiterMatcher;
162 /**
163 * Variable resolution is delegated to an implementer of VariableResolver.
164 */
165 private StrLookup variableResolver;
166 /**
167 * The flag whether substitution in variable names is enabled.
168 */
169 private boolean enableSubstitutionInVariables;
170
171 //-----------------------------------------------------------------------
172 /**
173 * Creates a new instance with defaults for variable prefix and suffix
174 * and the escaping character.
175 */
176 public StrSubstitutor() {
177 this(null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
178 }
179 /**
180 * Creates a new instance and initializes it. Uses defaults for variable
181 * prefix and suffix and the escaping character.
182 *
183 * @param valueMap the map with the variables' values, may be null
184 */
185 public StrSubstitutor(final Map<String, String> valueMap) {
186 this(new MapLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
187 }
188
189 /**
190 * Creates a new instance and initializes it. Uses a default escaping character.
191 *
192 * @param valueMap the map with the variables' values, may be null
193 * @param prefix the prefix for variables, not null
194 * @param suffix the suffix for variables, not null
195 * @throws IllegalArgumentException if the prefix or suffix is null
196 */
197 public StrSubstitutor(final Map<String, String> valueMap, final String prefix, final String suffix) {
198 this(new MapLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE);
199 }
200
201 /**
202 * Creates a new instance and initializes it.
203 *
204 * @param valueMap the map with the variables' values, may be null
205 * @param prefix the prefix for variables, not null
206 * @param suffix the suffix for variables, not null
207 * @param escape the escape character
208 * @throws IllegalArgumentException if the prefix or suffix is null
209 */
210 public StrSubstitutor(final Map<String, String> valueMap, final String prefix, final String suffix,
211 final char escape) {
212 this(new MapLookup(valueMap), prefix, suffix, escape);
213 }
214
215 /**
216 * Creates a new instance and initializes it.
217 *
218 * @param valueMap the map with the variables' values, may be null
219 * @param prefix the prefix for variables, not null
220 * @param suffix the suffix for variables, not null
221 * @param escape the escape character
222 * @param valueDelimiter the variable default value delimiter, may be null
223 * @throws IllegalArgumentException if the prefix or suffix is null
224 */
225 public StrSubstitutor(final Map<String, String> valueMap, final String prefix, final String suffix,
226 final char escape, final String valueDelimiter) {
227 this(new MapLookup(valueMap), prefix, suffix, escape, valueDelimiter);
228 }
229
230 /**
231 * Creates a new instance and initializes it.
232 *
233 * @param variableResolver the variable resolver, may be null
234 */
235 public StrSubstitutor(final StrLookup variableResolver) {
236 this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
237 }
238
239 /**
240 * Creates a new instance and initializes it.
241 *
242 * @param variableResolver the variable resolver, may be null
243 * @param prefix the prefix for variables, not null
244 * @param suffix the suffix for variables, not null
245 * @param escape the escape character
246 * @throws IllegalArgumentException if the prefix or suffix is null
247 */
248 public StrSubstitutor(final StrLookup variableResolver, final String prefix, final String suffix,
249 final char escape) {
250 this.setVariableResolver(variableResolver);
251 this.setVariablePrefix(prefix);
252 this.setVariableSuffix(suffix);
253 this.setEscapeChar(escape);
254 }
255
256 /**
257 * Creates a new instance and initializes it.
258 *
259 * @param variableResolver the variable resolver, may be null
260 * @param prefix the prefix for variables, not null
261 * @param suffix the suffix for variables, not null
262 * @param escape the escape character
263 * @param valueDelimiter the variable default value delimiter string, may be null
264 * @throws IllegalArgumentException if the prefix or suffix is null
265 */
266 public StrSubstitutor(final StrLookup variableResolver, final String prefix, final String suffix, final char escape, final String valueDelimiter) {
267 this.setVariableResolver(variableResolver);
268 this.setVariablePrefix(prefix);
269 this.setVariableSuffix(suffix);
270 this.setEscapeChar(escape);
271 this.setValueDelimiter(valueDelimiter);
272 }
273
274 /**
275 * Creates a new instance and initializes it.
276 *
277 * @param variableResolver the variable resolver, may be null
278 * @param prefixMatcher the prefix for variables, not null
279 * @param suffixMatcher the suffix for variables, not null
280 * @param escape the escape character
281 * @throws IllegalArgumentException if the prefix or suffix is null
282 */
283 public StrSubstitutor(final StrLookup variableResolver, final StrMatcher prefixMatcher,
284 final StrMatcher suffixMatcher,
285 final char escape) {
286 this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER);
287 }
288
289 /**
290 * Creates a new instance and initializes it.
291 *
292 * @param variableResolver the variable resolver, may be null
293 * @param prefixMatcher the prefix for variables, not null
294 * @param suffixMatcher the suffix for variables, not null
295 * @param escape the escape character
296 * @param valueDelimiterMatcher the variable default value delimiter matcher, may be null
297 * @throws IllegalArgumentException if the prefix or suffix is null
298 */
299 public StrSubstitutor(
300 final StrLookup variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher, final char escape, final StrMatcher valueDelimiterMatcher) {
301 this.setVariableResolver(variableResolver);
302 this.setVariablePrefixMatcher(prefixMatcher);
303 this.setVariableSuffixMatcher(suffixMatcher);
304 this.setEscapeChar(escape);
305 this.setValueDelimiterMatcher(valueDelimiterMatcher);
306 }
307
308 //-----------------------------------------------------------------------
309 /**
310 * Replaces all the occurrences of variables in the given source object with
311 * their matching values from the map.
312 *
313 * @param source the source text containing the variables to substitute, null returns null
314 * @param valueMap the map with the values, may be null
315 * @return the result of the replace operation
316 */
317 public static String replace(final Object source, final Map<String, String> valueMap) {
318 return new StrSubstitutor(valueMap).replace(source);
319 }
320
321 /**
322 * Replaces all the occurrences of variables in the given source object with
323 * their matching values from the map. This method allows to specify a
324 * custom variable prefix and suffix
325 *
326 * @param source the source text containing the variables to substitute, null returns null
327 * @param valueMap the map with the values, may be null
328 * @param prefix the prefix of variables, not null
329 * @param suffix the suffix of variables, not null
330 * @return the result of the replace operation
331 * @throws IllegalArgumentException if the prefix or suffix is null
332 */
333 public static String replace(final Object source, final Map<String, String> valueMap, final String prefix,
334 final String suffix) {
335 return new StrSubstitutor(valueMap, prefix, suffix).replace(source);
336 }
337
338 /**
339 * Replaces all the occurrences of variables in the given source object with their matching
340 * values from the properties.
341 *
342 * @param source the source text containing the variables to substitute, null returns null
343 * @param valueProperties the properties with values, may be null
344 * @return the result of the replace operation
345 */
346 public static String replace(final Object source, final Properties valueProperties) {
347 if (valueProperties == null) {
348 return source.toString();
349 }
350 final Map<String, String> valueMap = new HashMap<String, String>();
351 final Enumeration<?> propNames = valueProperties.propertyNames();
352 while (propNames.hasMoreElements()) {
353 final String propName = (String) propNames.nextElement();
354 final String propValue = valueProperties.getProperty(propName);
355 valueMap.put(propName, propValue);
356 }
357 return StrSubstitutor.replace(source, valueMap);
358 }
359
360 //-----------------------------------------------------------------------
361 /**
362 * Replaces all the occurrences of variables with their matching values
363 * from the resolver using the given source string as a template.
364 *
365 * @param source the string to replace in, null returns null
366 * @return the result of the replace operation
367 */
368 public String replace(final String source) {
369 return replace(null, source);
370 }
371 //-----------------------------------------------------------------------
372 /**
373 * Replaces all the occurrences of variables with their matching values
374 * from the resolver using the given source string as a template.
375 *
376 * @param event The current LogEvent if there is one.
377 * @param source the string to replace in, null returns null
378 * @return the result of the replace operation
379 */
380 public String replace(final LogEvent event, final String source) {
381 if (source == null) {
382 return null;
383 }
384 final StringBuilder buf = new StringBuilder(source);
385 if (!substitute(event, buf, 0, source.length())) {
386 return source;
387 }
388 return buf.toString();
389 }
390
391 /**
392 * Replaces all the occurrences of variables with their matching values
393 * from the resolver using the given source string as a template.
394 * <p>
395 * Only the specified portion of the string will be processed.
396 * The rest of the string is not processed, and is not returned.
397 *
398 * @param source the string to replace in, null returns null
399 * @param offset the start offset within the array, must be valid
400 * @param length the length within the array to be processed, must be valid
401 * @return the result of the replace operation
402 */
403 public String replace(final String source, final int offset, final int length) {
404 return replace(null, source, offset, length);
405 }
406
407 /**
408 * Replaces all the occurrences of variables with their matching values
409 * from the resolver using the given source string as a template.
410 * <p>
411 * Only the specified portion of the string will be processed.
412 * The rest of the string is not processed, and is not returned.
413 *
414 * @param event the current LogEvent, if one exists.
415 * @param source the string to replace in, null returns null
416 * @param offset the start offset within the array, must be valid
417 * @param length the length within the array to be processed, must be valid
418 * @return the result of the replace operation
419 */
420 public String replace(final LogEvent event, final String source, final int offset, final int length) {
421 if (source == null) {
422 return null;
423 }
424 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
425 if (!substitute(event, buf, 0, length)) {
426 return source.substring(offset, offset + length);
427 }
428 return buf.toString();
429 }
430
431 //-----------------------------------------------------------------------
432 /**
433 * Replaces all the occurrences of variables with their matching values
434 * from the resolver using the given source array as a template.
435 * The array is not altered by this method.
436 *
437 * @param source the character array to replace in, not altered, null returns null
438 * @return the result of the replace operation
439 */
440 public String replace(final char[] source) {
441 return replace(null, source);
442 }
443
444 //-----------------------------------------------------------------------
445 /**
446 * Replaces all the occurrences of variables with their matching values
447 * from the resolver using the given source array as a template.
448 * The array is not altered by this method.
449 *
450 * @param event the current LogEvent, if one exists.
451 * @param source the character array to replace in, not altered, null returns null
452 * @return the result of the replace operation
453 */
454 public String replace(final LogEvent event, final char[] source) {
455 if (source == null) {
456 return null;
457 }
458 final StringBuilder buf = new StringBuilder(source.length).append(source);
459 substitute(event, buf, 0, source.length);
460 return buf.toString();
461 }
462
463 /**
464 * Replaces all the occurrences of variables with their matching values
465 * from the resolver using the given source array as a template.
466 * The array is not altered by this method.
467 * <p>
468 * Only the specified portion of the array will be processed.
469 * The rest of the array is not processed, and is not returned.
470 *
471 * @param source the character array to replace in, not altered, null returns null
472 * @param offset the start offset within the array, must be valid
473 * @param length the length within the array to be processed, must be valid
474 * @return the result of the replace operation
475 */
476 public String replace(final char[] source, final int offset, final int length) {
477 return replace(null, source, offset, length);
478 }
479
480 /**
481 * Replaces all the occurrences of variables with their matching values
482 * from the resolver using the given source array as a template.
483 * The array is not altered by this method.
484 * <p>
485 * Only the specified portion of the array will be processed.
486 * The rest of the array is not processed, and is not returned.
487 *
488 * @param event the current LogEvent, if one exists.
489 * @param source the character array to replace in, not altered, null returns null
490 * @param offset the start offset within the array, must be valid
491 * @param length the length within the array to be processed, must be valid
492 * @return the result of the replace operation
493 */
494 public String replace(final LogEvent event, final char[] source, final int offset, final int length) {
495 if (source == null) {
496 return null;
497 }
498 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
499 substitute(event, buf, 0, length);
500 return buf.toString();
501 }
502
503 //-----------------------------------------------------------------------
504 /**
505 * Replaces all the occurrences of variables with their matching values
506 * from the resolver using the given source buffer as a template.
507 * The buffer is not altered by this method.
508 *
509 * @param source the buffer to use as a template, not changed, null returns null
510 * @return the result of the replace operation
511 */
512 public String replace(final StringBuffer source) {
513 return replace(null, source);
514 }
515
516 //-----------------------------------------------------------------------
517 /**
518 * Replaces all the occurrences of variables with their matching values
519 * from the resolver using the given source buffer as a template.
520 * The buffer is not altered by this method.
521 *
522 * @param event the current LogEvent, if one exists.
523 * @param source the buffer to use as a template, not changed, null returns null
524 * @return the result of the replace operation
525 */
526 public String replace(final LogEvent event, final StringBuffer source) {
527 if (source == null) {
528 return null;
529 }
530 final StringBuilder buf = new StringBuilder(source.length()).append(source);
531 substitute(event, buf, 0, buf.length());
532 return buf.toString();
533 }
534
535 /**
536 * Replaces all the occurrences of variables with their matching values
537 * from the resolver using the given source buffer as a template.
538 * The buffer is not altered by this method.
539 * <p>
540 * Only the specified portion of the buffer will be processed.
541 * The rest of the buffer is not processed, and is not returned.
542 *
543 * @param source the buffer to use as a template, not changed, null returns null
544 * @param offset the start offset within the array, must be valid
545 * @param length the length within the array to be processed, must be valid
546 * @return the result of the replace operation
547 */
548 public String replace(final StringBuffer source, final int offset, final int length) {
549 return replace(null, source, offset, length);
550 }
551
552 /**
553 * Replaces all the occurrences of variables with their matching values
554 * from the resolver using the given source buffer as a template.
555 * The buffer is not altered by this method.
556 * <p>
557 * Only the specified portion of the buffer will be processed.
558 * The rest of the buffer is not processed, and is not returned.
559 *
560 * @param event the current LogEvent, if one exists.
561 * @param source the buffer to use as a template, not changed, null returns null
562 * @param offset the start offset within the array, must be valid
563 * @param length the length within the array to be processed, must be valid
564 * @return the result of the replace operation
565 */
566 public String replace(final LogEvent event, final StringBuffer source, final int offset, final int length) {
567 if (source == null) {
568 return null;
569 }
570 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
571 substitute(event, buf, 0, length);
572 return buf.toString();
573 }
574
575 //-----------------------------------------------------------------------
576 /**
577 * Replaces all the occurrences of variables with their matching values
578 * from the resolver using the given source builder as a template.
579 * The builder is not altered by this method.
580 *
581 * @param source the builder to use as a template, not changed, null returns null
582 * @return the result of the replace operation
583 */
584 public String replace(final StringBuilder source) {
585 return replace(null, source);
586 }
587
588 //-----------------------------------------------------------------------
589 /**
590 * Replaces all the occurrences of variables with their matching values
591 * from the resolver using the given source builder as a template.
592 * The builder is not altered by this method.
593 *
594 * @param event The LogEvent.
595 * @param source the builder to use as a template, not changed, null returns null.
596 * @return the result of the replace operation.
597 */
598 public String replace(final LogEvent event, final StringBuilder source) {
599 if (source == null) {
600 return null;
601 }
602 final StringBuilder buf = new StringBuilder(source.length()).append(source);
603 substitute(event, buf, 0, buf.length());
604 return buf.toString();
605 }
606 /**
607 * Replaces all the occurrences of variables with their matching values
608 * from the resolver using the given source builder as a template.
609 * The builder is not altered by this method.
610 * <p>
611 * Only the specified portion of the builder will be processed.
612 * The rest of the builder is not processed, and is not returned.
613 *
614 * @param source the builder to use as a template, not changed, null returns null
615 * @param offset the start offset within the array, must be valid
616 * @param length the length within the array to be processed, must be valid
617 * @return the result of the replace operation
618 */
619 public String replace(final StringBuilder source, final int offset, final int length) {
620 return replace(null, source, offset, length);
621 }
622
623 /**
624 * Replaces all the occurrences of variables with their matching values
625 * from the resolver using the given source builder as a template.
626 * The builder is not altered by this method.
627 * <p>
628 * Only the specified portion of the builder will be processed.
629 * The rest of the builder is not processed, and is not returned.
630 *
631 * @param event the current LogEvent, if one exists.
632 * @param source the builder to use as a template, not changed, null returns null
633 * @param offset the start offset within the array, must be valid
634 * @param length the length within the array to be processed, must be valid
635 * @return the result of the replace operation
636 */
637 public String replace(final LogEvent event, final StringBuilder source, final int offset, final int length) {
638 if (source == null) {
639 return null;
640 }
641 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
642 substitute(event, buf, 0, length);
643 return buf.toString();
644 }
645
646 //-----------------------------------------------------------------------
647 /**
648 * Replaces all the occurrences of variables in the given source object with
649 * their matching values from the resolver. The input source object is
650 * converted to a string using <code>toString</code> and is not altered.
651 *
652 * @param source the source to replace in, null returns null
653 * @return the result of the replace operation
654 */
655 public String replace(final Object source) {
656 return replace(null, source);
657 }
658 //-----------------------------------------------------------------------
659 /**
660 * Replaces all the occurrences of variables in the given source object with
661 * their matching values from the resolver. The input source object is
662 * converted to a string using <code>toString</code> and is not altered.
663 *
664 * @param event the current LogEvent, if one exists.
665 * @param source the source to replace in, null returns null
666 * @return the result of the replace operation
667 */
668 public String replace(final LogEvent event, final Object source) {
669 if (source == null) {
670 return null;
671 }
672 final StringBuilder buf = new StringBuilder().append(source);
673 substitute(event, buf, 0, buf.length());
674 return buf.toString();
675 }
676
677 //-----------------------------------------------------------------------
678 /**
679 * Replaces all the occurrences of variables within the given source buffer
680 * with their matching values from the resolver.
681 * The buffer is updated with the result.
682 *
683 * @param source the buffer to replace in, updated, null returns zero
684 * @return true if altered
685 */
686 public boolean replaceIn(final StringBuffer source) {
687 if (source == null) {
688 return false;
689 }
690 return replaceIn(source, 0, source.length());
691 }
692
693 /**
694 * Replaces all the occurrences of variables within the given source buffer
695 * with their matching values from the resolver.
696 * The buffer is updated with the result.
697 * <p>
698 * Only the specified portion of the buffer will be processed.
699 * The rest of the buffer is not processed, but it is not deleted.
700 *
701 * @param source the buffer to replace in, updated, null returns zero
702 * @param offset the start offset within the array, must be valid
703 * @param length the length within the buffer to be processed, must be valid
704 * @return true if altered
705 */
706 public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
707 return replaceIn(null, source, offset, length);
708 }
709
710 /**
711 * Replaces all the occurrences of variables within the given source buffer
712 * with their matching values from the resolver.
713 * The buffer is updated with the result.
714 * <p>
715 * Only the specified portion of the buffer will be processed.
716 * The rest of the buffer is not processed, but it is not deleted.
717 *
718 * @param event the current LogEvent, if one exists.
719 * @param source the buffer to replace in, updated, null returns zero
720 * @param offset the start offset within the array, must be valid
721 * @param length the length within the buffer to be processed, must be valid
722 * @return true if altered
723 */
724 public boolean replaceIn(final LogEvent event, final StringBuffer source, final int offset, final int length) {
725 if (source == null) {
726 return false;
727 }
728 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
729 if (!substitute(event, buf, 0, length)) {
730 return false;
731 }
732 source.replace(offset, offset + length, buf.toString());
733 return true;
734 }
735
736 //-----------------------------------------------------------------------
737 /**
738 * Replaces all the occurrences of variables within the given source
739 * builder with their matching values from the resolver.
740 *
741 * @param source the builder to replace in, updated, null returns zero
742 * @return true if altered
743 */
744 public boolean replaceIn(final StringBuilder source) {
745 return replaceIn(null, source);
746 }
747
748 //-----------------------------------------------------------------------
749 /**
750 * Replaces all the occurrences of variables within the given source
751 * builder with their matching values from the resolver.
752 *
753 * @param event the current LogEvent, if one exists.
754 * @param source the builder to replace in, updated, null returns zero
755 * @return true if altered
756 */
757 public boolean replaceIn(final LogEvent event, final StringBuilder source) {
758 if (source == null) {
759 return false;
760 }
761 return substitute(event, source, 0, source.length());
762 }
763 /**
764 * Replaces all the occurrences of variables within the given source
765 * builder with their matching values from the resolver.
766 * <p>
767 * Only the specified portion of the builder will be processed.
768 * The rest of the builder is not processed, but it is not deleted.
769 *
770 * @param source the builder to replace in, null returns zero
771 * @param offset the start offset within the array, must be valid
772 * @param length the length within the builder to be processed, must be valid
773 * @return true if altered
774 */
775 public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
776 return replaceIn(null, source, offset, length);
777 }
778
779 /**
780 * Replaces all the occurrences of variables within the given source
781 * builder with their matching values from the resolver.
782 * <p>
783 * Only the specified portion of the builder will be processed.
784 * The rest of the builder is not processed, but it is not deleted.
785 *
786 * @param event the current LogEvent, if one is present.
787 * @param source the builder to replace in, null returns zero
788 * @param offset the start offset within the array, must be valid
789 * @param length the length within the builder to be processed, must be valid
790 * @return true if altered
791 */
792 public boolean replaceIn(final LogEvent event, final StringBuilder source, final int offset, final int length) {
793 if (source == null) {
794 return false;
795 }
796 return substitute(event, source, offset, length);
797 }
798
799 //-----------------------------------------------------------------------
800 /**
801 * Internal method that substitutes the variables.
802 * <p>
803 * Most users of this class do not need to call this method. This method will
804 * be called automatically by another (public) method.
805 * <p>
806 * Writers of subclasses can override this method if they need access to
807 * the substitution process at the start or end.
808 *
809 * @param event The current LogEvent, if there is one.
810 * @param buf the string builder to substitute into, not null
811 * @param offset the start offset within the builder, must be valid
812 * @param length the length within the builder to be processed, must be valid
813 * @return true if altered
814 */
815 protected boolean substitute(final LogEvent event, final StringBuilder buf, final int offset, final int length) {
816 return substitute(event, buf, offset, length, null) > 0;
817 }
818
819 /**
820 * Recursive handler for multiple levels of interpolation. This is the main
821 * interpolation method, which resolves the values of all variable references
822 * contained in the passed in text.
823 *
824 * @param event The current LogEvent, if there is one.
825 * @param buf the string builder to substitute into, not null
826 * @param offset the start offset within the builder, must be valid
827 * @param length the length within the builder to be processed, must be valid
828 * @param priorVariables the stack keeping track of the replaced variables, may be null
829 * @return the length change that occurs, unless priorVariables is null when the int
830 * represents a boolean flag as to whether any change occurred.
831 */
832 private int substitute(final LogEvent event, final StringBuilder buf, final int offset, final int length,
833 List<String> priorVariables) {
834 final StrMatcher prefixMatcher = getVariablePrefixMatcher();
835 final StrMatcher suffixMatcher = getVariableSuffixMatcher();
836 final char escape = getEscapeChar();
837 final StrMatcher valueDelimiterMatcher = getValueDelimiterMatcher();
838 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
839
840 final boolean top = (priorVariables == null);
841 boolean altered = false;
842 int lengthChange = 0;
843 char[] chars = getChars(buf);
844 int bufEnd = offset + length;
845 int pos = offset;
846 while (pos < bufEnd) {
847 final int startMatchLen = prefixMatcher.isMatch(chars, pos, offset,
848 bufEnd);
849 if (startMatchLen == 0) {
850 pos++;
851 } else {
852 // found variable start marker
853 if (pos > offset && chars[pos - 1] == escape) {
854 // escaped
855 buf.deleteCharAt(pos - 1);
856 chars = getChars(buf);
857 lengthChange--;
858 altered = true;
859 bufEnd--;
860 } else {
861 // find suffix
862 final int startPos = pos;
863 pos += startMatchLen;
864 int endMatchLen = 0;
865 int nestedVarCount = 0;
866 while (pos < bufEnd) {
867 if (substitutionInVariablesEnabled
868 && (endMatchLen = prefixMatcher.isMatch(chars,
869 pos, offset, bufEnd)) != 0) {
870 // found a nested variable start
871 nestedVarCount++;
872 pos += endMatchLen;
873 continue;
874 }
875
876 endMatchLen = suffixMatcher.isMatch(chars, pos, offset,
877 bufEnd);
878 if (endMatchLen == 0) {
879 pos++;
880 } else {
881 // found variable end marker
882 if (nestedVarCount == 0) {
883 String varNameExpr = new String(chars, startPos
884 + startMatchLen, pos - startPos
885 - startMatchLen);
886 if (substitutionInVariablesEnabled) {
887 final StringBuilder bufName = new StringBuilder(varNameExpr);
888 substitute(event, bufName, 0, bufName.length());
889 varNameExpr = bufName.toString();
890 }
891 pos += endMatchLen;
892 final int endPos = pos;
893
894 String varName = varNameExpr;
895 String varDefaultValue = null;
896
897 if (valueDelimiterMatcher != null) {
898 final char [] varNameExprChars = varNameExpr.toCharArray();
899 int valueDelimiterMatchLen = 0;
900 for (int i = 0; i < varNameExprChars.length; i++) {
901 // if there's any nested variable when nested variable substitution disabled, then stop resolving name and default value.
902 if (!substitutionInVariablesEnabled
903 && prefixMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) {
904 break;
905 }
906 if ((valueDelimiterMatchLen = valueDelimiterMatcher.isMatch(varNameExprChars, i)) != 0) {
907 varName = varNameExpr.substring(0, i);
908 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
909 break;
910 }
911 }
912 }
913
914 // on the first call initialize priorVariables
915 if (priorVariables == null) {
916 priorVariables = new ArrayList<String>();
917 priorVariables.add(new String(chars,
918 offset, length + lengthChange));
919 }
920
921 // handle cyclic substitution
922 checkCyclicSubstitution(varName, priorVariables);
923 priorVariables.add(varName);
924
925 // resolve the variable
926 String varValue = resolveVariable(event, varName, buf,
927 startPos, endPos);
928 if (varValue == null) {
929 varValue = varDefaultValue;
930 }
931 if (varValue != null) {
932 // recursive replace
933 final int varLen = varValue.length();
934 buf.replace(startPos, endPos, varValue);
935 altered = true;
936 int change = substitute(event, buf, startPos,
937 varLen, priorVariables);
938 change = change
939 + (varLen - (endPos - startPos));
940 pos += change;
941 bufEnd += change;
942 lengthChange += change;
943 chars = getChars(buf); // in case buffer was
944 // altered
945 }
946
947 // remove variable from the cyclic stack
948 priorVariables
949 .remove(priorVariables.size() - 1);
950 break;
951 } else {
952 nestedVarCount--;
953 pos += endMatchLen;
954 }
955 }
956 }
957 }
958 }
959 }
960 if (top) {
961 return altered ? 1 : 0;
962 }
963 return lengthChange;
964 }
965
966 /**
967 * Checks if the specified variable is already in the stack (list) of variables.
968 *
969 * @param varName the variable name to check
970 * @param priorVariables the list of prior variables
971 */
972 private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) {
973 if (!priorVariables.contains(varName)) {
974 return;
975 }
976 final StringBuilder buf = new StringBuilder(BUF_SIZE);
977 buf.append("Infinite loop in property interpolation of ");
978 buf.append(priorVariables.remove(0));
979 buf.append(": ");
980 appendWithSeparators(buf, priorVariables, "->");
981 throw new IllegalStateException(buf.toString());
982 }
983
984 /**
985 * Internal method that resolves the value of a variable.
986 * <p>
987 * Most users of this class do not need to call this method. This method is
988 * called automatically by the substitution process.
989 * <p>
990 * Writers of subclasses can override this method if they need to alter
991 * how each substitution occurs. The method is passed the variable's name
992 * and must return the corresponding value. This implementation uses the
993 * {@link #getVariableResolver()} with the variable's name as the key.
994 *
995 * @param event The LogEvent, if there is one.
996 * @param variableName the name of the variable, not null
997 * @param buf the buffer where the substitution is occurring, not null
998 * @param startPos the start position of the variable including the prefix, valid
999 * @param endPos the end position of the variable including the suffix, valid
1000 * @return the variable's value or <b>null</b> if the variable is unknown
1001 */
1002 protected String resolveVariable(final LogEvent event, final String variableName, final StringBuilder buf,
1003 final int startPos, final int endPos) {
1004 final StrLookup resolver = getVariableResolver();
1005 if (resolver == null) {
1006 return null;
1007 }
1008 return resolver.lookup(event, variableName);
1009 }
1010
1011 // Escape
1012 //-----------------------------------------------------------------------
1013 /**
1014 * Returns the escape character.
1015 *
1016 * @return the character used for escaping variable references
1017 */
1018 public char getEscapeChar() {
1019 return this.escapeChar;
1020 }
1021
1022 /**
1023 * Sets the escape character.
1024 * If this character is placed before a variable reference in the source
1025 * text, this variable will be ignored.
1026 *
1027 * @param escapeCharacter the escape character (0 for disabling escaping)
1028 */
1029 public void setEscapeChar(final char escapeCharacter) {
1030 this.escapeChar = escapeCharacter;
1031 }
1032
1033 // Prefix
1034 //-----------------------------------------------------------------------
1035 /**
1036 * Gets the variable prefix matcher currently in use.
1037 * <p>
1038 * The variable prefix is the character or characters that identify the
1039 * start of a variable. This prefix is expressed in terms of a matcher
1040 * allowing advanced prefix matches.
1041 *
1042 * @return the prefix matcher in use
1043 */
1044 public StrMatcher getVariablePrefixMatcher() {
1045 return prefixMatcher;
1046 }
1047
1048 /**
1049 * Sets the variable prefix matcher currently in use.
1050 * <p>
1051 * The variable prefix is the character or characters that identify the
1052 * start of a variable. This prefix is expressed in terms of a matcher
1053 * allowing advanced prefix matches.
1054 *
1055 * @param prefixMatcher the prefix matcher to use, null ignored
1056 * @return this, to enable chaining
1057 * @throws IllegalArgumentException if the prefix matcher is null
1058 */
1059 public StrSubstitutor setVariablePrefixMatcher(final StrMatcher prefixMatcher) {
1060 if (prefixMatcher == null) {
1061 throw new IllegalArgumentException("Variable prefix matcher must not be null!");
1062 }
1063 this.prefixMatcher = prefixMatcher;
1064 return this;
1065 }
1066
1067 /**
1068 * Sets the variable prefix to use.
1069 * <p>
1070 * The variable prefix is the character or characters that identify the
1071 * start of a variable. This method allows a single character prefix to
1072 * be easily set.
1073 *
1074 * @param prefix the prefix character to use
1075 * @return this, to enable chaining
1076 */
1077 public StrSubstitutor setVariablePrefix(final char prefix) {
1078 return setVariablePrefixMatcher(StrMatcher.charMatcher(prefix));
1079 }
1080
1081 /**
1082 * Sets the variable prefix to use.
1083 * <p>
1084 * The variable prefix is the character or characters that identify the
1085 * start of a variable. This method allows a string prefix to be easily set.
1086 *
1087 * @param prefix the prefix for variables, not null
1088 * @return this, to enable chaining
1089 * @throws IllegalArgumentException if the prefix is null
1090 */
1091 public StrSubstitutor setVariablePrefix(final String prefix) {
1092 if (prefix == null) {
1093 throw new IllegalArgumentException("Variable prefix must not be null!");
1094 }
1095 return setVariablePrefixMatcher(StrMatcher.stringMatcher(prefix));
1096 }
1097
1098 // Suffix
1099 //-----------------------------------------------------------------------
1100 /**
1101 * Gets the variable suffix matcher currently in use.
1102 * <p>
1103 * The variable suffix is the character or characters that identify the
1104 * end of a variable. This suffix is expressed in terms of a matcher
1105 * allowing advanced suffix matches.
1106 *
1107 * @return the suffix matcher in use
1108 */
1109 public StrMatcher getVariableSuffixMatcher() {
1110 return suffixMatcher;
1111 }
1112
1113 /**
1114 * Sets the variable suffix matcher currently in use.
1115 * <p>
1116 * The variable suffix is the character or characters that identify the
1117 * end of a variable. This suffix is expressed in terms of a matcher
1118 * allowing advanced suffix matches.
1119 *
1120 * @param suffixMatcher the suffix matcher to use, null ignored
1121 * @return this, to enable chaining
1122 * @throws IllegalArgumentException if the suffix matcher is null
1123 */
1124 public StrSubstitutor setVariableSuffixMatcher(final StrMatcher suffixMatcher) {
1125 if (suffixMatcher == null) {
1126 throw new IllegalArgumentException("Variable suffix matcher must not be null!");
1127 }
1128 this.suffixMatcher = suffixMatcher;
1129 return this;
1130 }
1131
1132 /**
1133 * Sets the variable suffix to use.
1134 * <p>
1135 * The variable suffix is the character or characters that identify the
1136 * end of a variable. This method allows a single character suffix to
1137 * be easily set.
1138 *
1139 * @param suffix the suffix character to use
1140 * @return this, to enable chaining
1141 */
1142 public StrSubstitutor setVariableSuffix(final char suffix) {
1143 return setVariableSuffixMatcher(StrMatcher.charMatcher(suffix));
1144 }
1145
1146 /**
1147 * Sets the variable suffix to use.
1148 * <p>
1149 * The variable suffix is the character or characters that identify the
1150 * end of a variable. This method allows a string suffix to be easily set.
1151 *
1152 * @param suffix the suffix for variables, not null
1153 * @return this, to enable chaining
1154 * @throws IllegalArgumentException if the suffix is null
1155 */
1156 public StrSubstitutor setVariableSuffix(final String suffix) {
1157 if (suffix == null) {
1158 throw new IllegalArgumentException("Variable suffix must not be null!");
1159 }
1160 return setVariableSuffixMatcher(StrMatcher.stringMatcher(suffix));
1161 }
1162
1163 // Variable Default Value Delimiter
1164 //-----------------------------------------------------------------------
1165 /**
1166 * Gets the variable default value delimiter matcher currently in use.
1167 * <p>
1168 * The variable default value delimiter is the characer or characters that delimite the
1169 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
1170 * allowing advanced variable default value delimiter matches.
1171 * <p>
1172 * If it returns null, then the variable default value resolution is disabled.
1173 *
1174 * @return the variable default value delimiter matcher in use, may be null
1175 */
1176 public StrMatcher getValueDelimiterMatcher() {
1177 return valueDelimiterMatcher;
1178 }
1179
1180 /**
1181 * Sets the variable default value delimiter matcher to use.
1182 * <p>
1183 * The variable default value delimiter is the characer or characters that delimite the
1184 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
1185 * allowing advanced variable default value delimiter matches.
1186 * <p>
1187 * If the <code>valueDelimiterMatcher</code> is null, then the variable default value resolution
1188 * becomes disabled.
1189 *
1190 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null
1191 * @return this, to enable chaining
1192 */
1193 public StrSubstitutor setValueDelimiterMatcher(final StrMatcher valueDelimiterMatcher) {
1194 this.valueDelimiterMatcher = valueDelimiterMatcher;
1195 return this;
1196 }
1197
1198 /**
1199 * Sets the variable default value delimiter to use.
1200 * <p>
1201 * The variable default value delimiter is the characer or characters that delimite the
1202 * variable name and the variable default value. This method allows a single character
1203 * variable default value delimiter to be easily set.
1204 *
1205 * @param valueDelimiter the variable default value delimiter character to use
1206 * @return this, to enable chaining
1207 */
1208 public StrSubstitutor setValueDelimiter(final char valueDelimiter) {
1209 return setValueDelimiterMatcher(StrMatcher.charMatcher(valueDelimiter));
1210 }
1211
1212 /**
1213 * Sets the variable default value delimiter to use.
1214 * <p>
1215 * The variable default value delimiter is the characer or characters that delimite the
1216 * variable name and the variable default value. This method allows a string
1217 * variable default value delimiter to be easily set.
1218 * <p>
1219 * If the <code>valueDelimiter</code> is null or empty string, then the variable default
1220 * value resolution becomes disabled.
1221 *
1222 * @param valueDelimiter the variable default value delimiter string to use, may be null or empty
1223 * @return this, to enable chaining
1224 */
1225 public StrSubstitutor setValueDelimiter(final String valueDelimiter) {
1226 if (Strings.isEmpty(valueDelimiter)) {
1227 setValueDelimiterMatcher(null);
1228 return this;
1229 }
1230 return setValueDelimiterMatcher(StrMatcher.stringMatcher(valueDelimiter));
1231 }
1232
1233 // Resolver
1234 //-----------------------------------------------------------------------
1235 /**
1236 * Gets the VariableResolver that is used to lookup variables.
1237 *
1238 * @return the VariableResolver
1239 */
1240 public StrLookup getVariableResolver() {
1241 return this.variableResolver;
1242 }
1243
1244 /**
1245 * Sets the VariableResolver that is used to lookup variables.
1246 *
1247 * @param variableResolver the VariableResolver
1248 */
1249 public void setVariableResolver(final StrLookup variableResolver) {
1250 this.variableResolver = variableResolver;
1251 }
1252
1253 // Substitution support in variable names
1254 //-----------------------------------------------------------------------
1255 /**
1256 * Returns a flag whether substitution is done in variable names.
1257 *
1258 * @return the substitution in variable names flag
1259 */
1260 public boolean isEnableSubstitutionInVariables() {
1261 return enableSubstitutionInVariables;
1262 }
1263
1264 /**
1265 * Sets a flag whether substitution is done in variable names. If set to
1266 * <b>true</b>, the names of variables can contain other variables which are
1267 * processed first before the original variable is evaluated, e.g.
1268 * <code>${jre-${java.version}}</code>. The default value is <b>false</b>.
1269 *
1270 * @param enableSubstitutionInVariables the new value of the flag
1271 */
1272 public void setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) {
1273 this.enableSubstitutionInVariables = enableSubstitutionInVariables;
1274 }
1275
1276 private char[] getChars(final StringBuilder sb) {
1277 final char[] chars = new char[sb.length()];
1278 sb.getChars(0, sb.length(), chars, 0);
1279 return chars;
1280 }
1281
1282 /**
1283 * Appends a iterable placing separators between each value, but
1284 * not before the first or after the last.
1285 * Appending a null iterable will have no effect..
1286 *
1287 * @param sb StringBuilder that contains the String being constructed.
1288 * @param iterable the iterable to append
1289 * @param separator the separator to use, null means no separator
1290 */
1291 public void appendWithSeparators(final StringBuilder sb, final Iterable<?> iterable, String separator) {
1292 if (iterable != null) {
1293 separator = (separator == null ? Strings.EMPTY : separator);
1294 final Iterator<?> it = iterable.iterator();
1295 while (it.hasNext()) {
1296 sb.append(it.next());
1297 if (it.hasNext()) {
1298 sb.append(separator);
1299 }
1300 }
1301 }
1302 }
1303
1304 @Override
1305 public String toString() {
1306 return "StrSubstitutor(" + variableResolver.toString() + ')';
1307 }
1308 }