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 * <p>
38 * Variable values are typically resolved from a map, but could also be resolved
39 * from system properties, or by supplying a custom variable resolver.
40 * </p>
41 * <p>
42 * The simplest example is to use this class to replace Java System properties. For example:
43 * </p>
44 * <pre>
45 * StrSubstitutor.replaceSystemProperties(
46 * "You are running with java.version = ${java.version} and os.name = ${os.name}.");
47 * </pre>
48 * <p>
49 * Typical usage of this class follows the following pattern: First an instance is created
50 * and initialized with the map that contains the values for the available variables.
51 * If a prefix and/or suffix for variables should be used other than the default ones,
52 * the appropriate settings can be performed. After that the <code>replace()</code>
53 * method can be called passing in the source text for interpolation. In the returned
54 * text all variable references (as long as their values are known) will be resolved.
55 * The following example demonstrates this:
56 * </p>
57 * <pre>
58 * Map valuesMap = HashMap();
59 * valuesMap.put("animal", "quick brown fox");
60 * valuesMap.put("target", "lazy dog");
61 * String templateString = "The ${animal} jumped over the ${target}.";
62 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
63 * String resolvedString = sub.replace(templateString);
64 * </pre>
65 * <p>yielding:</p>
66 * <pre>
67 * The quick brown fox jumped over the lazy dog.
68 * </pre>
69 * <p>
70 * Also, this class allows to set a default value for unresolved variables.
71 * The default value for a variable can be appended to the variable name after the variable
72 * default value delimiter. The default value of the variable default value delimiter is ':-',
73 * as in bash and other *nix shells, as those are arguably where the default ${} delimiter set originated.
74 * The variable default value delimiter can be manually set by calling {@link #setValueDelimiterMatcher(StrMatcher)},
75 * {@link #setValueDelimiter(char)} or {@link #setValueDelimiter(String)}.
76 * The following shows an example with variable default value settings:
77 * </p>
78 * <pre>
79 * Map valuesMap = HashMap();
80 * valuesMap.put("animal", "quick brown fox");
81 * valuesMap.put("target", "lazy dog");
82 * String templateString = "The ${animal} jumped over the ${target}. ${undefined.number:-1234567890}.";
83 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
84 * String resolvedString = sub.replace(templateString);
85 * </pre>
86 * <p>yielding:</p>
87 * <pre>
88 * The quick brown fox jumped over the lazy dog. 1234567890.
89 * </pre>
90 * <p>
91 * In addition to this usage pattern there are some static convenience methods that
92 * cover the most common use cases. These methods can be used without the need of
93 * manually creating an instance. However if multiple replace operations are to be
94 * performed, creating and reusing an instance of this class will be more efficient.
95 * </p>
96 * <p>
97 * Variable replacement works in a recursive way. Thus, if a variable value contains
98 * a variable then that variable will also be replaced. Cyclic replacements are
99 * detected and will cause an exception to be thrown.
100 * </p>
101 * <p>
102 * Sometimes the interpolation's result must contain a variable prefix. As an example
103 * take the following source text:
104 * </p>
105 * <pre>
106 * The variable ${${name}} must be used.
107 * </pre>
108 * <p>
109 * Here only the variable's name referred to in the text should be replaced resulting
110 * in the text (assuming that the value of the <code>name</code> variable is <code>x</code>):
111 * </p>
112 * <pre>
113 * The variable ${x} must be used.
114 * </pre>
115 * <p>
116 * To achieve this effect there are two possibilities: Either set a different prefix
117 * and suffix for variables which do not conflict with the result text you want to
118 * produce. The other possibility is to use the escape character, by default '$'.
119 * If this character is placed before a variable reference, this reference is ignored
120 * and won't be replaced. For example:
121 * </p>
122 * <pre>
123 * The variable $${${name}} must be used.
124 * </pre>
125 * <p>
126 * In some complex scenarios you might even want to perform substitution in the
127 * names of variables, for instance
128 * </p>
129 * <pre>
130 * ${jre-${java.specification.version}}
131 * </pre>
132 * <p>
133 * <code>StrSubstitutor</code> supports this recursive substitution in variable
134 * names, but it has to be enabled explicitly by setting the
135 * {@link #setEnableSubstitutionInVariables(boolean) enableSubstitutionInVariables}
136 * property to <b>true</b>.
137 * </p>
138 */
139 public class StrSubstitutor {
140
141 /**
142 * Constant for the default escape character.
143 */
144 public static final char DEFAULT_ESCAPE = '$';
145
146 /**
147 * Constant for the default variable prefix.
148 */
149 public static final StrMatcher DEFAULT_PREFIX = StrMatcher.stringMatcher(DEFAULT_ESCAPE + "{");
150
151 /**
152 * Constant for the default variable suffix.
153 */
154 public static final StrMatcher DEFAULT_SUFFIX = StrMatcher.stringMatcher("}");
155
156 /**
157 * Constant for the default value delimiter of a variable.
158 */
159 public static final StrMatcher DEFAULT_VALUE_DELIMITER = StrMatcher.stringMatcher(":-");
160
161 private static final int BUF_SIZE = 256;
162
163 /**
164 * Stores the escape character.
165 */
166 private char escapeChar;
167 /**
168 * Stores the variable prefix.
169 */
170 private StrMatcher prefixMatcher;
171 /**
172 * Stores the variable suffix.
173 */
174 private StrMatcher suffixMatcher;
175 /**
176 * Stores the default variable value delimiter
177 */
178 private StrMatcher valueDelimiterMatcher;
179 /**
180 * Variable resolution is delegated to an implementer of VariableResolver.
181 */
182 private StrLookup variableResolver;
183 /**
184 * The flag whether substitution in variable names is enabled.
185 */
186 private boolean enableSubstitutionInVariables;
187
188 //-----------------------------------------------------------------------
189 /**
190 * Creates a new instance with defaults for variable prefix and suffix
191 * and the escaping character.
192 */
193 public StrSubstitutor() {
194 this(null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
195 }
196 /**
197 * Creates a new instance and initializes it. Uses defaults for variable
198 * prefix and suffix and the escaping character.
199 *
200 * @param valueMap the map with the variables' values, may be null
201 */
202 public StrSubstitutor(final Map<String, String> valueMap) {
203 this(new MapLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
204 }
205
206 /**
207 * Creates a new instance and initializes it. Uses a default escaping character.
208 *
209 * @param valueMap the map with the variables' values, may be null
210 * @param prefix the prefix for variables, not null
211 * @param suffix the suffix for variables, not null
212 * @throws IllegalArgumentException if the prefix or suffix is null
213 */
214 public StrSubstitutor(final Map<String, String> valueMap, final String prefix, final String suffix) {
215 this(new MapLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE);
216 }
217
218 /**
219 * Creates a new instance and initializes it.
220 *
221 * @param valueMap the map with the variables' values, may be null
222 * @param prefix the prefix for variables, not null
223 * @param suffix the suffix for variables, not null
224 * @param escape the escape character
225 * @throws IllegalArgumentException if the prefix or suffix is null
226 */
227 public StrSubstitutor(final Map<String, String> valueMap, final String prefix, final String suffix,
228 final char escape) {
229 this(new MapLookup(valueMap), prefix, suffix, escape);
230 }
231
232 /**
233 * Creates a new instance and initializes it.
234 *
235 * @param valueMap the map with the variables' values, may be null
236 * @param prefix the prefix for variables, not null
237 * @param suffix the suffix for variables, not null
238 * @param escape the escape character
239 * @param valueDelimiter the variable default value delimiter, may be null
240 * @throws IllegalArgumentException if the prefix or suffix is null
241 */
242 public StrSubstitutor(final Map<String, String> valueMap, final String prefix, final String suffix,
243 final char escape, final String valueDelimiter) {
244 this(new MapLookup(valueMap), prefix, suffix, escape, valueDelimiter);
245 }
246
247 /**
248 * Creates a new instance and initializes it.
249 *
250 * @param variableResolver the variable resolver, may be null
251 */
252 public StrSubstitutor(final StrLookup variableResolver) {
253 this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_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 * @throws IllegalArgumentException if the prefix or suffix is null
264 */
265 public StrSubstitutor(final StrLookup variableResolver, final String prefix, final String suffix,
266 final char escape) {
267 this.setVariableResolver(variableResolver);
268 this.setVariablePrefix(prefix);
269 this.setVariableSuffix(suffix);
270 this.setEscapeChar(escape);
271 }
272
273 /**
274 * Creates a new instance and initializes it.
275 *
276 * @param variableResolver the variable resolver, may be null
277 * @param prefix the prefix for variables, not null
278 * @param suffix the suffix for variables, not null
279 * @param escape the escape character
280 * @param valueDelimiter the variable default value delimiter string, may be null
281 * @throws IllegalArgumentException if the prefix or suffix is null
282 */
283 public StrSubstitutor(final StrLookup variableResolver, final String prefix, final String suffix, final char escape, final String valueDelimiter) {
284 this.setVariableResolver(variableResolver);
285 this.setVariablePrefix(prefix);
286 this.setVariableSuffix(suffix);
287 this.setEscapeChar(escape);
288 this.setValueDelimiter(valueDelimiter);
289 }
290
291 /**
292 * Creates a new instance and initializes it.
293 *
294 * @param variableResolver the variable resolver, may be null
295 * @param prefixMatcher the prefix for variables, not null
296 * @param suffixMatcher the suffix for variables, not null
297 * @param escape the escape character
298 * @throws IllegalArgumentException if the prefix or suffix is null
299 */
300 public StrSubstitutor(final StrLookup variableResolver, final StrMatcher prefixMatcher,
301 final StrMatcher suffixMatcher,
302 final char escape) {
303 this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER);
304 }
305
306 /**
307 * Creates a new instance and initializes it.
308 *
309 * @param variableResolver the variable resolver, may be null
310 * @param prefixMatcher the prefix for variables, not null
311 * @param suffixMatcher the suffix for variables, not null
312 * @param escape the escape character
313 * @param valueDelimiterMatcher the variable default value delimiter matcher, may be null
314 * @throws IllegalArgumentException if the prefix or suffix is null
315 */
316 public StrSubstitutor(
317 final StrLookup variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher, final char escape, final StrMatcher valueDelimiterMatcher) {
318 this.setVariableResolver(variableResolver);
319 this.setVariablePrefixMatcher(prefixMatcher);
320 this.setVariableSuffixMatcher(suffixMatcher);
321 this.setEscapeChar(escape);
322 this.setValueDelimiterMatcher(valueDelimiterMatcher);
323 }
324
325 //-----------------------------------------------------------------------
326 /**
327 * Replaces all the occurrences of variables in the given source object with
328 * their matching values from the map.
329 *
330 * @param source the source text containing the variables to substitute, null returns null
331 * @param valueMap the map with the values, may be null
332 * @return the result of the replace operation
333 */
334 public static String replace(final Object source, final Map<String, String> valueMap) {
335 return new StrSubstitutor(valueMap).replace(source);
336 }
337
338 /**
339 * Replaces all the occurrences of variables in the given source object with
340 * their matching values from the map. This method allows to specify a
341 * custom variable prefix and suffix
342 *
343 * @param source the source text containing the variables to substitute, null returns null
344 * @param valueMap the map with the values, may be null
345 * @param prefix the prefix of variables, not null
346 * @param suffix the suffix of variables, not null
347 * @return the result of the replace operation
348 * @throws IllegalArgumentException if the prefix or suffix is null
349 */
350 public static String replace(final Object source, final Map<String, String> valueMap, final String prefix,
351 final String suffix) {
352 return new StrSubstitutor(valueMap, prefix, suffix).replace(source);
353 }
354
355 /**
356 * Replaces all the occurrences of variables in the given source object with their matching
357 * values from the properties.
358 *
359 * @param source the source text containing the variables to substitute, null returns null
360 * @param valueProperties the properties with values, may be null
361 * @return the result of the replace operation
362 */
363 public static String replace(final Object source, final Properties valueProperties) {
364 if (valueProperties == null) {
365 return source.toString();
366 }
367 final Map<String, String> valueMap = new HashMap<String, String>();
368 final Enumeration<?> propNames = valueProperties.propertyNames();
369 while (propNames.hasMoreElements()) {
370 final String propName = (String) propNames.nextElement();
371 final String propValue = valueProperties.getProperty(propName);
372 valueMap.put(propName, propValue);
373 }
374 return StrSubstitutor.replace(source, valueMap);
375 }
376
377 //-----------------------------------------------------------------------
378 /**
379 * Replaces all the occurrences of variables with their matching values
380 * from the resolver using the given source string as a template.
381 *
382 * @param source the string to replace in, null returns null
383 * @return the result of the replace operation
384 */
385 public String replace(final String source) {
386 return replace(null, source);
387 }
388 //-----------------------------------------------------------------------
389 /**
390 * Replaces all the occurrences of variables with their matching values
391 * from the resolver using the given source string as a template.
392 *
393 * @param event The current LogEvent if there is one.
394 * @param source the string to replace in, null returns null
395 * @return the result of the replace operation
396 */
397 public String replace(final LogEvent event, final String source) {
398 if (source == null) {
399 return null;
400 }
401 final StringBuilder buf = new StringBuilder(source);
402 if (!substitute(event, buf, 0, source.length())) {
403 return source;
404 }
405 return buf.toString();
406 }
407
408 /**
409 * Replaces all the occurrences of variables with their matching values
410 * from the resolver using the given source string as a template.
411 * <p>
412 * Only the specified portion of the string will be processed.
413 * The rest of the string is not processed, and is not returned.
414 * </p>
415 *
416 * @param source the string to replace in, null returns null
417 * @param offset the start offset within the array, must be valid
418 * @param length the length within the array to be processed, must be valid
419 * @return the result of the replace operation
420 */
421 public String replace(final String source, final int offset, final int length) {
422 return replace(null, source, offset, length);
423 }
424
425 /**
426 * Replaces all the occurrences of variables with their matching values
427 * from the resolver using the given source string as a template.
428 * <p>
429 * Only the specified portion of the string will be processed.
430 * The rest of the string is not processed, and is not returned.
431 * </p>
432 *
433 * @param event the current LogEvent, if one exists.
434 * @param source the string to replace in, null returns null
435 * @param offset the start offset within the array, must be valid
436 * @param length the length within the array to be processed, must be valid
437 * @return the result of the replace operation
438 */
439 public String replace(final LogEvent event, final String source, final int offset, final int length) {
440 if (source == null) {
441 return null;
442 }
443 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
444 if (!substitute(event, buf, 0, length)) {
445 return source.substring(offset, offset + length);
446 }
447 return buf.toString();
448 }
449
450 //-----------------------------------------------------------------------
451 /**
452 * Replaces all the occurrences of variables with their matching values
453 * from the resolver using the given source array as a template.
454 * The array is not altered by this method.
455 *
456 * @param source the character array to replace in, not altered, null returns null
457 * @return the result of the replace operation
458 */
459 public String replace(final char[] source) {
460 return replace(null, source);
461 }
462
463 //-----------------------------------------------------------------------
464 /**
465 * Replaces all the occurrences of variables with their matching values
466 * from the resolver using the given source array as a template.
467 * The array is not altered by this method.
468 *
469 * @param event the current LogEvent, if one exists.
470 * @param source the character array to replace in, not altered, null returns null
471 * @return the result of the replace operation
472 */
473 public String replace(final LogEvent event, final char[] source) {
474 if (source == null) {
475 return null;
476 }
477 final StringBuilder buf = new StringBuilder(source.length).append(source);
478 substitute(event, buf, 0, source.length);
479 return buf.toString();
480 }
481
482 /**
483 * Replaces all the occurrences of variables with their matching values
484 * from the resolver using the given source array as a template.
485 * The array is not altered by this method.
486 * <p>
487 * Only the specified portion of the array will be processed.
488 * The rest of the array is not processed, and is not returned.
489 * </p>
490 *
491 * @param source the character array to replace in, not altered, null returns null
492 * @param offset the start offset within the array, must be valid
493 * @param length the length within the array to be processed, must be valid
494 * @return the result of the replace operation
495 */
496 public String replace(final char[] source, final int offset, final int length) {
497 return replace(null, source, offset, length);
498 }
499
500 /**
501 * Replaces all the occurrences of variables with their matching values
502 * from the resolver using the given source array as a template.
503 * The array is not altered by this method.
504 * <p>
505 * Only the specified portion of the array will be processed.
506 * The rest of the array is not processed, and is not returned.
507 * </p>
508 *
509 * @param event the current LogEvent, if one exists.
510 * @param source the character array to replace in, not altered, null returns null
511 * @param offset the start offset within the array, must be valid
512 * @param length the length within the array to be processed, must be valid
513 * @return the result of the replace operation
514 */
515 public String replace(final LogEvent event, final char[] source, final int offset, final int length) {
516 if (source == null) {
517 return null;
518 }
519 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
520 substitute(event, buf, 0, length);
521 return buf.toString();
522 }
523
524 //-----------------------------------------------------------------------
525 /**
526 * Replaces all the occurrences of variables with their matching values
527 * from the resolver using the given source buffer as a template.
528 * The buffer is not altered by this method.
529 *
530 * @param source the buffer to use as a template, not changed, null returns null
531 * @return the result of the replace operation
532 */
533 public String replace(final StringBuffer source) {
534 return replace(null, source);
535 }
536
537 //-----------------------------------------------------------------------
538 /**
539 * Replaces all the occurrences of variables with their matching values
540 * from the resolver using the given source buffer as a template.
541 * The buffer is not altered by this method.
542 *
543 * @param event the current LogEvent, if one exists.
544 * @param source the buffer to use as a template, not changed, null returns null
545 * @return the result of the replace operation
546 */
547 public String replace(final LogEvent event, final StringBuffer source) {
548 if (source == null) {
549 return null;
550 }
551 final StringBuilder buf = new StringBuilder(source.length()).append(source);
552 substitute(event, buf, 0, buf.length());
553 return buf.toString();
554 }
555
556 /**
557 * Replaces all the occurrences of variables with their matching values
558 * from the resolver using the given source buffer as a template.
559 * The buffer is not altered by this method.
560 * <p>
561 * Only the specified portion of the buffer will be processed.
562 * The rest of the buffer is not processed, and is not returned.
563 * </p>
564 *
565 * @param source the buffer 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 StringBuffer source, final int offset, final int length) {
571 return replace(null, source, offset, length);
572 }
573
574 /**
575 * Replaces all the occurrences of variables with their matching values
576 * from the resolver using the given source buffer as a template.
577 * The buffer is not altered by this method.
578 * <p>
579 * Only the specified portion of the buffer will be processed.
580 * The rest of the buffer is not processed, and is not returned.
581 * </p>
582 *
583 * @param event the current LogEvent, if one exists.
584 * @param source the buffer to use as a template, not changed, null returns null
585 * @param offset the start offset within the array, must be valid
586 * @param length the length within the array to be processed, must be valid
587 * @return the result of the replace operation
588 */
589 public String replace(final LogEvent event, final StringBuffer source, final int offset, final int length) {
590 if (source == null) {
591 return null;
592 }
593 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
594 substitute(event, buf, 0, length);
595 return buf.toString();
596 }
597
598 //-----------------------------------------------------------------------
599 /**
600 * Replaces all the occurrences of variables with their matching values
601 * from the resolver using the given source builder as a template.
602 * The builder is not altered by this method.
603 *
604 * @param source the builder to use as a template, not changed, null returns null
605 * @return the result of the replace operation
606 */
607 public String replace(final StringBuilder source) {
608 return replace(null, source);
609 }
610
611 //-----------------------------------------------------------------------
612 /**
613 * Replaces all the occurrences of variables with their matching values
614 * from the resolver using the given source builder as a template.
615 * The builder is not altered by this method.
616 *
617 * @param event The LogEvent.
618 * @param source the builder to use as a template, not changed, null returns null.
619 * @return the result of the replace operation.
620 */
621 public String replace(final LogEvent event, final StringBuilder source) {
622 if (source == null) {
623 return null;
624 }
625 final StringBuilder buf = new StringBuilder(source.length()).append(source);
626 substitute(event, buf, 0, buf.length());
627 return buf.toString();
628 }
629 /**
630 * Replaces all the occurrences of variables with their matching values
631 * from the resolver using the given source builder as a template.
632 * The builder is not altered by this method.
633 * <p>
634 * Only the specified portion of the builder will be processed.
635 * The rest of the builder is not processed, and is not returned.
636 * </p>
637 *
638 * @param source the builder to use as a template, not changed, null returns null
639 * @param offset the start offset within the array, must be valid
640 * @param length the length within the array to be processed, must be valid
641 * @return the result of the replace operation
642 */
643 public String replace(final StringBuilder source, final int offset, final int length) {
644 return replace(null, source, offset, length);
645 }
646
647 /**
648 * Replaces all the occurrences of variables with their matching values
649 * from the resolver using the given source builder as a template.
650 * The builder is not altered by this method.
651 * <p>
652 * Only the specified portion of the builder will be processed.
653 * The rest of the builder is not processed, and is not returned.
654 * </p>
655 *
656 * @param event the current LogEvent, if one exists.
657 * @param source the builder to use as a template, not changed, null returns null
658 * @param offset the start offset within the array, must be valid
659 * @param length the length within the array to be processed, must be valid
660 * @return the result of the replace operation
661 */
662 public String replace(final LogEvent event, final StringBuilder source, final int offset, final int length) {
663 if (source == null) {
664 return null;
665 }
666 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
667 substitute(event, buf, 0, length);
668 return buf.toString();
669 }
670
671 //-----------------------------------------------------------------------
672 /**
673 * Replaces all the occurrences of variables in the given source object with
674 * their matching values from the resolver. The input source object is
675 * converted to a string using <code>toString</code> and is not altered.
676 *
677 * @param source the source to replace in, null returns null
678 * @return the result of the replace operation
679 */
680 public String replace(final Object source) {
681 return replace(null, source);
682 }
683 //-----------------------------------------------------------------------
684 /**
685 * Replaces all the occurrences of variables in the given source object with
686 * their matching values from the resolver. The input source object is
687 * converted to a string using <code>toString</code> and is not altered.
688 *
689 * @param event the current LogEvent, if one exists.
690 * @param source the source to replace in, null returns null
691 * @return the result of the replace operation
692 */
693 public String replace(final LogEvent event, final Object source) {
694 if (source == null) {
695 return null;
696 }
697 final StringBuilder buf = new StringBuilder().append(source);
698 substitute(event, buf, 0, buf.length());
699 return buf.toString();
700 }
701
702 //-----------------------------------------------------------------------
703 /**
704 * Replaces all the occurrences of variables within the given source buffer
705 * with their matching values from the resolver.
706 * The buffer is updated with the result.
707 *
708 * @param source the buffer to replace in, updated, null returns zero
709 * @return true if altered
710 */
711 public boolean replaceIn(final StringBuffer source) {
712 if (source == null) {
713 return false;
714 }
715 return replaceIn(source, 0, source.length());
716 }
717
718 /**
719 * Replaces all the occurrences of variables within the given source buffer
720 * with their matching values from the resolver.
721 * The buffer is updated with the result.
722 * <p>
723 * Only the specified portion of the buffer will be processed.
724 * The rest of the buffer is not processed, but it is not deleted.
725 * </p>
726 *
727 * @param source the buffer to replace in, updated, null returns zero
728 * @param offset the start offset within the array, must be valid
729 * @param length the length within the buffer to be processed, must be valid
730 * @return true if altered
731 */
732 public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
733 return replaceIn(null, source, offset, length);
734 }
735
736 /**
737 * Replaces all the occurrences of variables within the given source buffer
738 * with their matching values from the resolver.
739 * The buffer is updated with the result.
740 * <p>
741 * Only the specified portion of the buffer will be processed.
742 * The rest of the buffer is not processed, but it is not deleted.
743 * </p>
744 *
745 * @param event the current LogEvent, if one exists.
746 * @param source the buffer to replace in, updated, null returns zero
747 * @param offset the start offset within the array, must be valid
748 * @param length the length within the buffer to be processed, must be valid
749 * @return true if altered
750 */
751 public boolean replaceIn(final LogEvent event, final StringBuffer source, final int offset, final int length) {
752 if (source == null) {
753 return false;
754 }
755 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
756 if (!substitute(event, buf, 0, length)) {
757 return false;
758 }
759 source.replace(offset, offset + length, buf.toString());
760 return true;
761 }
762
763 //-----------------------------------------------------------------------
764 /**
765 * Replaces all the occurrences of variables within the given source
766 * builder with their matching values from the resolver.
767 *
768 * @param source the builder to replace in, updated, null returns zero
769 * @return true if altered
770 */
771 public boolean replaceIn(final StringBuilder source) {
772 return replaceIn(null, source);
773 }
774
775 //-----------------------------------------------------------------------
776 /**
777 * Replaces all the occurrences of variables within the given source
778 * builder with their matching values from the resolver.
779 *
780 * @param event the current LogEvent, if one exists.
781 * @param source the builder to replace in, updated, null returns zero
782 * @return true if altered
783 */
784 public boolean replaceIn(final LogEvent event, final StringBuilder source) {
785 if (source == null) {
786 return false;
787 }
788 return substitute(event, source, 0, source.length());
789 }
790 /**
791 * Replaces all the occurrences of variables within the given source
792 * builder with their matching values from the resolver.
793 * <p>
794 * Only the specified portion of the builder will be processed.
795 * The rest of the builder is not processed, but it is not deleted.
796 * </p>
797 *
798 * @param source the builder to replace in, null returns zero
799 * @param offset the start offset within the array, must be valid
800 * @param length the length within the builder to be processed, must be valid
801 * @return true if altered
802 */
803 public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
804 return replaceIn(null, source, offset, length);
805 }
806
807 /**
808 * Replaces all the occurrences of variables within the given source
809 * builder with their matching values from the resolver.
810 * <p>
811 * Only the specified portion of the builder will be processed.
812 * The rest of the builder is not processed, but it is not deleted.
813 * </p>
814 *
815 * @param event the current LogEvent, if one is present.
816 * @param source the builder to replace in, null returns zero
817 * @param offset the start offset within the array, must be valid
818 * @param length the length within the builder to be processed, must be valid
819 * @return true if altered
820 */
821 public boolean replaceIn(final LogEvent event, final StringBuilder source, final int offset, final int length) {
822 if (source == null) {
823 return false;
824 }
825 return substitute(event, source, offset, length);
826 }
827
828 //-----------------------------------------------------------------------
829 /**
830 * Internal method that substitutes the variables.
831 * <p>
832 * Most users of this class do not need to call this method. This method will
833 * be called automatically by another (public) method.
834 * </p>
835 * <p>
836 * Writers of subclasses can override this method if they need access to
837 * the substitution process at the start or end.
838 * </p>
839 *
840 * @param event The current LogEvent, if there is one.
841 * @param buf the string builder to substitute into, not null
842 * @param offset the start offset within the builder, must be valid
843 * @param length the length within the builder to be processed, must be valid
844 * @return true if altered
845 */
846 protected boolean substitute(final LogEvent event, final StringBuilder buf, final int offset, final int length) {
847 return substitute(event, buf, offset, length, null) > 0;
848 }
849
850 /**
851 * Recursive handler for multiple levels of interpolation. This is the main
852 * interpolation method, which resolves the values of all variable references
853 * contained in the passed in text.
854 *
855 * @param event The current LogEvent, if there is one.
856 * @param buf the string builder to substitute into, not null
857 * @param offset the start offset within the builder, must be valid
858 * @param length the length within the builder to be processed, must be valid
859 * @param priorVariables the stack keeping track of the replaced variables, may be null
860 * @return the length change that occurs, unless priorVariables is null when the int
861 * represents a boolean flag as to whether any change occurred.
862 */
863 private int substitute(final LogEvent event, final StringBuilder buf, final int offset, final int length,
864 List<String> priorVariables) {
865 final StrMatcher prefixMatcher = getVariablePrefixMatcher();
866 final StrMatcher suffixMatcher = getVariableSuffixMatcher();
867 final char escape = getEscapeChar();
868 final StrMatcher valueDelimiterMatcher = getValueDelimiterMatcher();
869 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
870
871 final boolean top = (priorVariables == null);
872 boolean altered = false;
873 int lengthChange = 0;
874 char[] chars = getChars(buf);
875 int bufEnd = offset + length;
876 int pos = offset;
877 while (pos < bufEnd) {
878 final int startMatchLen = prefixMatcher.isMatch(chars, pos, offset,
879 bufEnd);
880 if (startMatchLen == 0) {
881 pos++;
882 } else {
883 // found variable start marker
884 if (pos > offset && chars[pos - 1] == escape) {
885 // escaped
886 buf.deleteCharAt(pos - 1);
887 chars = getChars(buf);
888 lengthChange--;
889 altered = true;
890 bufEnd--;
891 } else {
892 // find suffix
893 final int startPos = pos;
894 pos += startMatchLen;
895 int endMatchLen = 0;
896 int nestedVarCount = 0;
897 while (pos < bufEnd) {
898 if (substitutionInVariablesEnabled
899 && (endMatchLen = prefixMatcher.isMatch(chars,
900 pos, offset, bufEnd)) != 0) {
901 // found a nested variable start
902 nestedVarCount++;
903 pos += endMatchLen;
904 continue;
905 }
906
907 endMatchLen = suffixMatcher.isMatch(chars, pos, offset,
908 bufEnd);
909 if (endMatchLen == 0) {
910 pos++;
911 } else {
912 // found variable end marker
913 if (nestedVarCount == 0) {
914 String varNameExpr = new String(chars, startPos
915 + startMatchLen, pos - startPos
916 - startMatchLen);
917 if (substitutionInVariablesEnabled) {
918 final StringBuilder bufName = new StringBuilder(varNameExpr);
919 substitute(event, bufName, 0, bufName.length());
920 varNameExpr = bufName.toString();
921 }
922 pos += endMatchLen;
923 final int endPos = pos;
924
925 String varName = varNameExpr;
926 String varDefaultValue = null;
927
928 if (valueDelimiterMatcher != null) {
929 final char [] varNameExprChars = varNameExpr.toCharArray();
930 int valueDelimiterMatchLen = 0;
931 for (int i = 0; i < varNameExprChars.length; i++) {
932 // if there's any nested variable when nested variable substitution disabled, then stop resolving name and default value.
933 if (!substitutionInVariablesEnabled
934 && prefixMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) {
935 break;
936 }
937 if ((valueDelimiterMatchLen = valueDelimiterMatcher.isMatch(varNameExprChars, i)) != 0) {
938 varName = varNameExpr.substring(0, i);
939 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
940 break;
941 }
942 }
943 }
944
945 // on the first call initialize priorVariables
946 if (priorVariables == null) {
947 priorVariables = new ArrayList<String>();
948 priorVariables.add(new String(chars,
949 offset, length + lengthChange));
950 }
951
952 // handle cyclic substitution
953 checkCyclicSubstitution(varName, priorVariables);
954 priorVariables.add(varName);
955
956 // resolve the variable
957 String varValue = resolveVariable(event, varName, buf,
958 startPos, endPos);
959 if (varValue == null) {
960 varValue = varDefaultValue;
961 }
962 if (varValue != null) {
963 // recursive replace
964 final int varLen = varValue.length();
965 buf.replace(startPos, endPos, varValue);
966 altered = true;
967 int change = substitute(event, buf, startPos,
968 varLen, priorVariables);
969 change = change
970 + (varLen - (endPos - startPos));
971 pos += change;
972 bufEnd += change;
973 lengthChange += change;
974 chars = getChars(buf); // in case buffer was
975 // altered
976 }
977
978 // remove variable from the cyclic stack
979 priorVariables
980 .remove(priorVariables.size() - 1);
981 break;
982 } else {
983 nestedVarCount--;
984 pos += endMatchLen;
985 }
986 }
987 }
988 }
989 }
990 }
991 if (top) {
992 return altered ? 1 : 0;
993 }
994 return lengthChange;
995 }
996
997 /**
998 * Checks if the specified variable is already in the stack (list) of variables.
999 *
1000 * @param varName the variable name to check
1001 * @param priorVariables the list of prior variables
1002 */
1003 private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) {
1004 if (!priorVariables.contains(varName)) {
1005 return;
1006 }
1007 final StringBuilder buf = new StringBuilder(BUF_SIZE);
1008 buf.append("Infinite loop in property interpolation of ");
1009 buf.append(priorVariables.remove(0));
1010 buf.append(": ");
1011 appendWithSeparators(buf, priorVariables, "->");
1012 throw new IllegalStateException(buf.toString());
1013 }
1014
1015 /**
1016 * Internal method that resolves the value of a variable.
1017 * <p>
1018 * Most users of this class do not need to call this method. This method is
1019 * called automatically by the substitution process.
1020 * </p>
1021 * <p>
1022 * Writers of subclasses can override this method if they need to alter
1023 * how each substitution occurs. The method is passed the variable's name
1024 * and must return the corresponding value. This implementation uses the
1025 * {@link #getVariableResolver()} with the variable's name as the key.
1026 * </p>
1027 *
1028 * @param event The LogEvent, if there is one.
1029 * @param variableName the name of the variable, not null
1030 * @param buf the buffer where the substitution is occurring, not null
1031 * @param startPos the start position of the variable including the prefix, valid
1032 * @param endPos the end position of the variable including the suffix, valid
1033 * @return the variable's value or <b>null</b> if the variable is unknown
1034 */
1035 protected String resolveVariable(final LogEvent event, final String variableName, final StringBuilder buf,
1036 final int startPos, final int endPos) {
1037 final StrLookup resolver = getVariableResolver();
1038 if (resolver == null) {
1039 return null;
1040 }
1041 return resolver.lookup(event, variableName);
1042 }
1043
1044 // Escape
1045 //-----------------------------------------------------------------------
1046 /**
1047 * Returns the escape character.
1048 *
1049 * @return the character used for escaping variable references
1050 */
1051 public char getEscapeChar() {
1052 return this.escapeChar;
1053 }
1054
1055 /**
1056 * Sets the escape character.
1057 * If this character is placed before a variable reference in the source
1058 * text, this variable will be ignored.
1059 *
1060 * @param escapeCharacter the escape character (0 for disabling escaping)
1061 */
1062 public void setEscapeChar(final char escapeCharacter) {
1063 this.escapeChar = escapeCharacter;
1064 }
1065
1066 // Prefix
1067 //-----------------------------------------------------------------------
1068 /**
1069 * Gets the variable prefix matcher currently in use.
1070 * <p>
1071 * The variable prefix is the character or characters that identify the
1072 * start of a variable. This prefix is expressed in terms of a matcher
1073 * allowing advanced prefix matches.
1074 * </p>
1075 *
1076 * @return the prefix matcher in use
1077 */
1078 public StrMatcher getVariablePrefixMatcher() {
1079 return prefixMatcher;
1080 }
1081
1082 /**
1083 * Sets the variable prefix matcher currently in use.
1084 * <p>
1085 * The variable prefix is the character or characters that identify the
1086 * start of a variable. This prefix is expressed in terms of a matcher
1087 * allowing advanced prefix matches.
1088 * </p>
1089 *
1090 * @param prefixMatcher the prefix matcher to use, null ignored
1091 * @return this, to enable chaining
1092 * @throws IllegalArgumentException if the prefix matcher is null
1093 */
1094 public StrSubstitutor setVariablePrefixMatcher(final StrMatcher prefixMatcher) {
1095 if (prefixMatcher == null) {
1096 throw new IllegalArgumentException("Variable prefix matcher must not be null!");
1097 }
1098 this.prefixMatcher = prefixMatcher;
1099 return this;
1100 }
1101
1102 /**
1103 * Sets the variable prefix to use.
1104 * <p>
1105 * The variable prefix is the character or characters that identify the
1106 * start of a variable. This method allows a single character prefix to
1107 * be easily set.
1108 * </p>
1109 *
1110 * @param prefix the prefix character to use
1111 * @return this, to enable chaining
1112 */
1113 public StrSubstitutor setVariablePrefix(final char prefix) {
1114 return setVariablePrefixMatcher(StrMatcher.charMatcher(prefix));
1115 }
1116
1117 /**
1118 * Sets the variable prefix to use.
1119 * <p>
1120 * The variable prefix is the character or characters that identify the
1121 * start of a variable. This method allows a string prefix to be easily set.
1122 * </p>
1123 *
1124 * @param prefix the prefix for variables, not null
1125 * @return this, to enable chaining
1126 * @throws IllegalArgumentException if the prefix is null
1127 */
1128 public StrSubstitutor setVariablePrefix(final String prefix) {
1129 if (prefix == null) {
1130 throw new IllegalArgumentException("Variable prefix must not be null!");
1131 }
1132 return setVariablePrefixMatcher(StrMatcher.stringMatcher(prefix));
1133 }
1134
1135 // Suffix
1136 //-----------------------------------------------------------------------
1137 /**
1138 * Gets the variable suffix matcher currently in use.
1139 * <p>
1140 * The variable suffix is the character or characters that identify the
1141 * end of a variable. This suffix is expressed in terms of a matcher
1142 * allowing advanced suffix matches.
1143 * </p>
1144 *
1145 * @return the suffix matcher in use
1146 */
1147 public StrMatcher getVariableSuffixMatcher() {
1148 return suffixMatcher;
1149 }
1150
1151 /**
1152 * Sets the variable suffix matcher currently in use.
1153 * <p>
1154 * The variable suffix is the character or characters that identify the
1155 * end of a variable. This suffix is expressed in terms of a matcher
1156 * allowing advanced suffix matches.
1157 * </p>
1158 *
1159 * @param suffixMatcher the suffix matcher to use, null ignored
1160 * @return this, to enable chaining
1161 * @throws IllegalArgumentException if the suffix matcher is null
1162 */
1163 public StrSubstitutor setVariableSuffixMatcher(final StrMatcher suffixMatcher) {
1164 if (suffixMatcher == null) {
1165 throw new IllegalArgumentException("Variable suffix matcher must not be null!");
1166 }
1167 this.suffixMatcher = suffixMatcher;
1168 return this;
1169 }
1170
1171 /**
1172 * Sets the variable suffix to use.
1173 * <p>
1174 * The variable suffix is the character or characters that identify the
1175 * end of a variable. This method allows a single character suffix to
1176 * be easily set.
1177 * </p>
1178 *
1179 * @param suffix the suffix character to use
1180 * @return this, to enable chaining
1181 */
1182 public StrSubstitutor setVariableSuffix(final char suffix) {
1183 return setVariableSuffixMatcher(StrMatcher.charMatcher(suffix));
1184 }
1185
1186 /**
1187 * Sets the variable suffix to use.
1188 * <p>
1189 * The variable suffix is the character or characters that identify the
1190 * end of a variable. This method allows a string suffix to be easily set.
1191 * </p>
1192 *
1193 * @param suffix the suffix for variables, not null
1194 * @return this, to enable chaining
1195 * @throws IllegalArgumentException if the suffix is null
1196 */
1197 public StrSubstitutor setVariableSuffix(final String suffix) {
1198 if (suffix == null) {
1199 throw new IllegalArgumentException("Variable suffix must not be null!");
1200 }
1201 return setVariableSuffixMatcher(StrMatcher.stringMatcher(suffix));
1202 }
1203
1204 // Variable Default Value Delimiter
1205 //-----------------------------------------------------------------------
1206 /**
1207 * Gets the variable default value delimiter matcher currently in use.
1208 * <p>
1209 * The variable default value delimiter is the character or characters that delimit the
1210 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
1211 * allowing advanced variable default value delimiter matches.
1212 * </p>
1213 * <p>
1214 * If it returns null, then the variable default value resolution is disabled.
1215 * </p>
1216 *
1217 * @return the variable default value delimiter matcher in use, may be null
1218 */
1219 public StrMatcher getValueDelimiterMatcher() {
1220 return valueDelimiterMatcher;
1221 }
1222
1223 /**
1224 * Sets the variable default value delimiter matcher to use.
1225 * <p>
1226 * The variable default value delimiter is the character or characters that delimit the
1227 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
1228 * allowing advanced variable default value delimiter matches.
1229 * </p>
1230 * <p>
1231 * If the <code>valueDelimiterMatcher</code> is null, then the variable default value resolution
1232 * becomes disabled.
1233 * </p>
1234 *
1235 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null
1236 * @return this, to enable chaining
1237 */
1238 public StrSubstitutor setValueDelimiterMatcher(final StrMatcher valueDelimiterMatcher) {
1239 this.valueDelimiterMatcher = valueDelimiterMatcher;
1240 return this;
1241 }
1242
1243 /**
1244 * Sets the variable default value delimiter to use.
1245 * <p>
1246 * The variable default value delimiter is the character or characters that delimit the
1247 * variable name and the variable default value. This method allows a single character
1248 * variable default value delimiter to be easily set.
1249 * </p>
1250 *
1251 * @param valueDelimiter the variable default value delimiter character to use
1252 * @return this, to enable chaining
1253 */
1254 public StrSubstitutor setValueDelimiter(final char valueDelimiter) {
1255 return setValueDelimiterMatcher(StrMatcher.charMatcher(valueDelimiter));
1256 }
1257
1258 /**
1259 * Sets the variable default value delimiter to use.
1260 * <p>
1261 * The variable default value delimiter is the character or characters that delimit the
1262 * variable name and the variable default value. This method allows a string
1263 * variable default value delimiter to be easily set.
1264 * </p>
1265 * <p>
1266 * If the <code>valueDelimiter</code> is null or empty string, then the variable default
1267 * value resolution becomes disabled.
1268 * </p>
1269 *
1270 * @param valueDelimiter the variable default value delimiter string to use, may be null or empty
1271 * @return this, to enable chaining
1272 */
1273 public StrSubstitutor setValueDelimiter(final String valueDelimiter) {
1274 if (Strings.isEmpty(valueDelimiter)) {
1275 setValueDelimiterMatcher(null);
1276 return this;
1277 }
1278 return setValueDelimiterMatcher(StrMatcher.stringMatcher(valueDelimiter));
1279 }
1280
1281 // Resolver
1282 //-----------------------------------------------------------------------
1283 /**
1284 * Gets the VariableResolver that is used to lookup variables.
1285 *
1286 * @return the VariableResolver
1287 */
1288 public StrLookup getVariableResolver() {
1289 return this.variableResolver;
1290 }
1291
1292 /**
1293 * Sets the VariableResolver that is used to lookup variables.
1294 *
1295 * @param variableResolver the VariableResolver
1296 */
1297 public void setVariableResolver(final StrLookup variableResolver) {
1298 this.variableResolver = variableResolver;
1299 }
1300
1301 // Substitution support in variable names
1302 //-----------------------------------------------------------------------
1303 /**
1304 * Returns a flag whether substitution is done in variable names.
1305 *
1306 * @return the substitution in variable names flag
1307 */
1308 public boolean isEnableSubstitutionInVariables() {
1309 return enableSubstitutionInVariables;
1310 }
1311
1312 /**
1313 * Sets a flag whether substitution is done in variable names. If set to
1314 * <b>true</b>, the names of variables can contain other variables which are
1315 * processed first before the original variable is evaluated, e.g.
1316 * <code>${jre-${java.version}}</code>. The default value is <b>false</b>.
1317 *
1318 * @param enableSubstitutionInVariables the new value of the flag
1319 */
1320 public void setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) {
1321 this.enableSubstitutionInVariables = enableSubstitutionInVariables;
1322 }
1323
1324 private char[] getChars(final StringBuilder sb) {
1325 final char[] chars = new char[sb.length()];
1326 sb.getChars(0, sb.length(), chars, 0);
1327 return chars;
1328 }
1329
1330 /**
1331 * Appends a iterable placing separators between each value, but
1332 * not before the first or after the last.
1333 * Appending a null iterable will have no effect..
1334 *
1335 * @param sb StringBuilder that contains the String being constructed.
1336 * @param iterable the iterable to append
1337 * @param separator the separator to use, null means no separator
1338 */
1339 public void appendWithSeparators(final StringBuilder sb, final Iterable<?> iterable, String separator) {
1340 if (iterable != null) {
1341 separator = separator == null ? Strings.EMPTY : separator;
1342 final Iterator<?> it = iterable.iterator();
1343 while (it.hasNext()) {
1344 sb.append(it.next());
1345 if (it.hasNext()) {
1346 sb.append(separator);
1347 }
1348 }
1349 }
1350 }
1351
1352 @Override
1353 public String toString() {
1354 return "StrSubstitutor(" + variableResolver.toString() + ')';
1355 }
1356 }