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.core.config.Configuration;
29 import org.apache.logging.log4j.core.config.ConfigurationAware;
30 import org.apache.logging.log4j.util.Strings;
31
32 /**
33 * Substitutes variables within a string by values.
34 * <p>
35 * This class takes a piece of text and substitutes all the variables within it.
36 * The default definition of a variable is <code>${variableName}</code>.
37 * The prefix and suffix can be changed via constructors and set methods.
38 * </p>
39 * <p>
40 * Variable values are typically resolved from a map, but could also be resolved
41 * from system properties, or by supplying a custom variable resolver.
42 * </p>
43 * <p>
44 * The simplest example is to use this class to replace Java System properties. For example:
45 * </p>
46 * <pre>
47 * StrSubstitutor.replaceSystemProperties(
48 * "You are running with java.version = ${java.version} and os.name = ${os.name}.");
49 * </pre>
50 * <p>
51 * Typical usage of this class follows the following pattern: First an instance is created
52 * and initialized with the map that contains the values for the available variables.
53 * If a prefix and/or suffix for variables should be used other than the default ones,
54 * the appropriate settings can be performed. After that the <code>replace()</code>
55 * method can be called passing in the source text for interpolation. In the returned
56 * text all variable references (as long as their values are known) will be resolved.
57 * The following example demonstrates this:
58 * </p>
59 * <pre>
60 * Map valuesMap = HashMap();
61 * valuesMap.put("animal", "quick brown fox");
62 * valuesMap.put("target", "lazy dog");
63 * String templateString = "The ${animal} jumped over the ${target}.";
64 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
65 * String resolvedString = sub.replace(templateString);
66 * </pre>
67 * <p>yielding:</p>
68 * <pre>
69 * The quick brown fox jumped over the lazy dog.
70 * </pre>
71 * <p>
72 * Also, this class allows to set a default value for unresolved variables.
73 * The default value for a variable can be appended to the variable name after the variable
74 * default value delimiter. The default value of the variable default value delimiter is ':-',
75 * as in bash and other *nix shells, as those are arguably where the default ${} delimiter set originated.
76 * The variable default value delimiter can be manually set by calling {@link #setValueDelimiterMatcher(StrMatcher)},
77 * {@link #setValueDelimiter(char)} or {@link #setValueDelimiter(String)}.
78 * The following shows an example with variable default value settings:
79 * </p>
80 * <pre>
81 * Map valuesMap = HashMap();
82 * valuesMap.put("animal", "quick brown fox");
83 * valuesMap.put("target", "lazy dog");
84 * String templateString = "The ${animal} jumped over the ${target}. ${undefined.number:-1234567890}.";
85 * StrSubstitutor sub = new StrSubstitutor(valuesMap);
86 * String resolvedString = sub.replace(templateString);
87 * </pre>
88 * <p>yielding:</p>
89 * <pre>
90 * The quick brown fox jumped over the lazy dog. 1234567890.
91 * </pre>
92 * <p>
93 * In addition to this usage pattern there are some static convenience methods that
94 * cover the most common use cases. These methods can be used without the need of
95 * manually creating an instance. However if multiple replace operations are to be
96 * performed, creating and reusing an instance of this class will be more efficient.
97 * </p>
98 * <p>
99 * Variable replacement works in a recursive way. Thus, if a variable value contains
100 * a variable then that variable will also be replaced. Cyclic replacements are
101 * detected and will cause an exception to be thrown.
102 * </p>
103 * <p>
104 * Sometimes the interpolation's result must contain a variable prefix. As an example
105 * take the following source text:
106 * </p>
107 * <pre>
108 * The variable ${${name}} must be used.
109 * </pre>
110 * <p>
111 * Here only the variable's name referred to in the text should be replaced resulting
112 * in the text (assuming that the value of the <code>name</code> variable is <code>x</code>):
113 * </p>
114 * <pre>
115 * The variable ${x} must be used.
116 * </pre>
117 * <p>
118 * To achieve this effect there are two possibilities: Either set a different prefix
119 * and suffix for variables which do not conflict with the result text you want to
120 * produce. The other possibility is to use the escape character, by default '$'.
121 * If this character is placed before a variable reference, this reference is ignored
122 * and won't be replaced. For example:
123 * </p>
124 * <pre>
125 * The variable $${${name}} must be used.
126 * </pre>
127 * <p>
128 * In some complex scenarios you might even want to perform substitution in the
129 * names of variables, for instance
130 * </p>
131 * <pre>
132 * ${jre-${java.specification.version}}
133 * </pre>
134 * <p>
135 * <code>StrSubstitutor</code> supports this recursive substitution in variable
136 * names, but it has to be enabled explicitly by setting the
137 * {@link #setEnableSubstitutionInVariables(boolean) enableSubstitutionInVariables}
138 * property to <b>true</b>.
139 * </p>
140 */
141 public class StrSubstitutor implements ConfigurationAware {
142
143 /**
144 * Constant for the default escape character.
145 */
146 public static final char DEFAULT_ESCAPE = '$';
147
148 /**
149 * Constant for the default variable prefix.
150 */
151 public static final StrMatcher DEFAULT_PREFIX = StrMatcher.stringMatcher(DEFAULT_ESCAPE + "{");
152
153 /**
154 * Constant for the default variable suffix.
155 */
156 public static final StrMatcher DEFAULT_SUFFIX = StrMatcher.stringMatcher("}");
157
158 /**
159 * Constant for the default value delimiter of a variable.
160 */
161 public static final StrMatcher DEFAULT_VALUE_DELIMITER = StrMatcher.stringMatcher(":-");
162
163 private static final int BUF_SIZE = 256;
164
165 /**
166 * Stores the escape character.
167 */
168 private char escapeChar;
169 /**
170 * Stores the variable prefix.
171 */
172 private StrMatcher prefixMatcher;
173 /**
174 * Stores the variable suffix.
175 */
176 private StrMatcher suffixMatcher;
177 /**
178 * Stores the default variable value delimiter
179 */
180 private StrMatcher valueDelimiterMatcher;
181 /**
182 * Variable resolution is delegated to an implementer of VariableResolver.
183 */
184 private StrLookup variableResolver;
185 /**
186 * The flag whether substitution in variable names is enabled.
187 */
188 private boolean enableSubstitutionInVariables = true;
189 /**
190 * The currently active Configuration for use by ConfigurationAware StrLookup implementations.
191 */
192 private Configuration configuration;
193
194 //-----------------------------------------------------------------------
195 /**
196 * Creates a new instance with defaults for variable prefix and suffix
197 * and the escaping character.
198 */
199 public StrSubstitutor() {
200 this(null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
201 }
202
203 /**
204 * Creates a new instance and initializes it. Uses defaults for variable
205 * prefix and suffix and the escaping character.
206 *
207 * @param valueMap the map with the variables' values, may be null
208 */
209 public StrSubstitutor(final Map<String, String> valueMap) {
210 this(new MapLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE);
211 }
212
213 /**
214 * Creates a new instance and initializes it. Uses a default escaping character.
215 *
216 * @param valueMap the map with the variables' values, may be null
217 * @param prefix the prefix for variables, not null
218 * @param suffix the suffix for variables, not null
219 * @throws IllegalArgumentException if the prefix or suffix is null
220 */
221 public StrSubstitutor(final Map<String, String> valueMap, final String prefix, final String suffix) {
222 this(new MapLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE);
223 }
224
225 /**
226 * Creates a new instance and initializes it.
227 *
228 * @param valueMap the map with the variables' values, may be null
229 * @param prefix the prefix for variables, not null
230 * @param suffix the suffix for variables, not null
231 * @param escape the escape character
232 * @throws IllegalArgumentException if the prefix or suffix is null
233 */
234 public StrSubstitutor(final Map<String, String> valueMap, final String prefix, final String suffix,
235 final char escape) {
236 this(new MapLookup(valueMap), prefix, suffix, escape);
237 }
238
239 /**
240 * Creates a new instance and initializes it.
241 *
242 * @param valueMap the map with the variables' values, 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 * @param valueDelimiter the variable default value delimiter, may be null
247 * @throws IllegalArgumentException if the prefix or suffix is null
248 */
249 public StrSubstitutor(final Map<String, String> valueMap, final String prefix, final String suffix,
250 final char escape, final String valueDelimiter) {
251 this(new MapLookup(valueMap), prefix, suffix, escape, valueDelimiter);
252 }
253
254 /**
255 * Creates a new instance and initializes it. Uses defaults for variable
256 * prefix and suffix and the escaping character.
257 *
258 * @param properties the map with the variables' values, may be null
259 */
260 public StrSubstitutor(final Properties properties) {
261 this(toTypeSafeMap(properties));
262 }
263
264 /**
265 * Creates a new instance and initializes it.
266 *
267 * @param variableResolver the variable resolver, may be null
268 */
269 public StrSubstitutor(final StrLookup variableResolver) {
270 this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_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 * @throws IllegalArgumentException if the prefix or suffix is null
281 */
282 public StrSubstitutor(final StrLookup variableResolver, final String prefix, final String suffix,
283 final char escape) {
284 this.setVariableResolver(variableResolver);
285 this.setVariablePrefix(prefix);
286 this.setVariableSuffix(suffix);
287 this.setEscapeChar(escape);
288 }
289
290 /**
291 * Creates a new instance and initializes it.
292 *
293 * @param variableResolver the variable resolver, may be null
294 * @param prefix the prefix for variables, not null
295 * @param suffix the suffix for variables, not null
296 * @param escape the escape character
297 * @param valueDelimiter the variable default value delimiter string, may be null
298 * @throws IllegalArgumentException if the prefix or suffix is null
299 */
300 public StrSubstitutor(final StrLookup variableResolver, final String prefix, final String suffix, final char escape, final String valueDelimiter) {
301 this.setVariableResolver(variableResolver);
302 this.setVariablePrefix(prefix);
303 this.setVariableSuffix(suffix);
304 this.setEscapeChar(escape);
305 this.setValueDelimiter(valueDelimiter);
306 }
307
308 /**
309 * Creates a new instance and initializes it.
310 *
311 * @param variableResolver the variable resolver, may be null
312 * @param prefixMatcher the prefix for variables, not null
313 * @param suffixMatcher the suffix for variables, not null
314 * @param escape the escape character
315 * @throws IllegalArgumentException if the prefix or suffix is null
316 */
317 public StrSubstitutor(final StrLookup variableResolver, final StrMatcher prefixMatcher,
318 final StrMatcher suffixMatcher,
319 final char escape) {
320 this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER);
321 }
322
323 /**
324 * Creates a new instance and initializes it.
325 *
326 * @param variableResolver the variable resolver, may be null
327 * @param prefixMatcher the prefix for variables, not null
328 * @param suffixMatcher the suffix for variables, not null
329 * @param escape the escape character
330 * @param valueDelimiterMatcher the variable default value delimiter matcher, may be null
331 * @throws IllegalArgumentException if the prefix or suffix is null
332 */
333 public StrSubstitutor(
334 final StrLookup variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher, final char escape, final StrMatcher valueDelimiterMatcher) {
335 this.setVariableResolver(variableResolver);
336 this.setVariablePrefixMatcher(prefixMatcher);
337 this.setVariableSuffixMatcher(suffixMatcher);
338 this.setEscapeChar(escape);
339 this.setValueDelimiterMatcher(valueDelimiterMatcher);
340 }
341
342 //-----------------------------------------------------------------------
343 /**
344 * Replaces all the occurrences of variables in the given source object with
345 * their matching values from the map.
346 *
347 * @param source the source text containing the variables to substitute, null returns null
348 * @param valueMap the map with the values, may be null
349 * @return the result of the replace operation
350 */
351 public static String replace(final Object source, final Map<String, String> valueMap) {
352 return new StrSubstitutor(valueMap).replace(source);
353 }
354
355 /**
356 * Replaces all the occurrences of variables in the given source object with
357 * their matching values from the map. This method allows to specify a
358 * custom variable prefix and suffix
359 *
360 * @param source the source text containing the variables to substitute, null returns null
361 * @param valueMap the map with the values, may be null
362 * @param prefix the prefix of variables, not null
363 * @param suffix the suffix of variables, not null
364 * @return the result of the replace operation
365 * @throws IllegalArgumentException if the prefix or suffix is null
366 */
367 public static String replace(final Object source, final Map<String, String> valueMap, final String prefix,
368 final String suffix) {
369 return new StrSubstitutor(valueMap, prefix, suffix).replace(source);
370 }
371
372 /**
373 * Replaces all the occurrences of variables in the given source object with their matching
374 * values from the properties.
375 *
376 * @param source the source text containing the variables to substitute, null returns null
377 * @param valueProperties the properties with values, may be null
378 * @return the result of the replace operation
379 */
380 public static String replace(final Object source, final Properties valueProperties) {
381 if (valueProperties == null) {
382 return source.toString();
383 }
384 final Map<String, String> valueMap = new HashMap<>();
385 final Enumeration<?> propNames = valueProperties.propertyNames();
386 while (propNames.hasMoreElements()) {
387 final String propName = (String) propNames.nextElement();
388 final String propValue = valueProperties.getProperty(propName);
389 valueMap.put(propName, propValue);
390 }
391 return StrSubstitutor.replace(source, valueMap);
392 }
393
394 private static Map<String, String> toTypeSafeMap(final Properties properties) {
395 final Map<String, String> map = new HashMap<>(properties.size());
396 for (final String name : properties.stringPropertyNames()) {
397 map.put(name, properties.getProperty(name));
398 }
399 return map;
400 }
401
402 //-----------------------------------------------------------------------
403 /**
404 * Replaces all the occurrences of variables with their matching values
405 * from the resolver using the given source string as a template.
406 *
407 * @param source the string to replace in, null returns null
408 * @return the result of the replace operation
409 */
410 public String replace(final String source) {
411 return replace(null, source);
412 }
413 //-----------------------------------------------------------------------
414 /**
415 * Replaces all the occurrences of variables with their matching values
416 * from the resolver using the given source string as a template.
417 *
418 * @param event The current LogEvent if there is one.
419 * @param source the string to replace in, null returns null
420 * @return the result of the replace operation
421 */
422 public String replace(final LogEvent event, final String source) {
423 if (source == null) {
424 return null;
425 }
426 final StringBuilder buf = new StringBuilder(source);
427 if (!substitute(event, buf, 0, source.length())) {
428 return source;
429 }
430 return buf.toString();
431 }
432
433 /**
434 * Replaces all the occurrences of variables with their matching values
435 * from the resolver using the given source string as a template.
436 * <p>
437 * Only the specified portion of the string will be processed.
438 * The rest of the string is not processed, and is not returned.
439 * </p>
440 *
441 * @param source the string to replace in, null returns null
442 * @param offset the start offset within the array, must be valid
443 * @param length the length within the array to be processed, must be valid
444 * @return the result of the replace operation
445 */
446 public String replace(final String source, final int offset, final int length) {
447 return replace(null, source, offset, length);
448 }
449
450 /**
451 * Replaces all the occurrences of variables with their matching values
452 * from the resolver using the given source string as a template.
453 * <p>
454 * Only the specified portion of the string will be processed.
455 * The rest of the string is not processed, and is not returned.
456 * </p>
457 *
458 * @param event the current LogEvent, if one exists.
459 * @param source the string to replace in, null returns null
460 * @param offset the start offset within the array, must be valid
461 * @param length the length within the array to be processed, must be valid
462 * @return the result of the replace operation
463 */
464 public String replace(final LogEvent event, final String source, final int offset, final int length) {
465 if (source == null) {
466 return null;
467 }
468 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
469 if (!substitute(event, buf, 0, length)) {
470 return source.substring(offset, offset + length);
471 }
472 return buf.toString();
473 }
474
475 //-----------------------------------------------------------------------
476 /**
477 * Replaces all the occurrences of variables with their matching values
478 * from the resolver using the given source array as a template.
479 * The array is not altered by this method.
480 *
481 * @param source the character array to replace in, not altered, null returns null
482 * @return the result of the replace operation
483 */
484 public String replace(final char[] source) {
485 return replace(null, source);
486 }
487
488 //-----------------------------------------------------------------------
489 /**
490 * Replaces all the occurrences of variables with their matching values
491 * from the resolver using the given source array as a template.
492 * The array is not altered by this method.
493 *
494 * @param event the current LogEvent, if one exists.
495 * @param source the character array to replace in, not altered, null returns null
496 * @return the result of the replace operation
497 */
498 public String replace(final LogEvent event, final char[] source) {
499 if (source == null) {
500 return null;
501 }
502 final StringBuilder buf = new StringBuilder(source.length).append(source);
503 substitute(event, buf, 0, source.length);
504 return buf.toString();
505 }
506
507 /**
508 * Replaces all the occurrences of variables with their matching values
509 * from the resolver using the given source array as a template.
510 * The array is not altered by this method.
511 * <p>
512 * Only the specified portion of the array will be processed.
513 * The rest of the array is not processed, and is not returned.
514 * </p>
515 *
516 * @param source the character array to replace in, not altered, null returns null
517 * @param offset the start offset within the array, must be valid
518 * @param length the length within the array to be processed, must be valid
519 * @return the result of the replace operation
520 */
521 public String replace(final char[] source, final int offset, final int length) {
522 return replace(null, source, offset, length);
523 }
524
525 /**
526 * Replaces all the occurrences of variables with their matching values
527 * from the resolver using the given source array as a template.
528 * The array is not altered by this method.
529 * <p>
530 * Only the specified portion of the array will be processed.
531 * The rest of the array is not processed, and is not returned.
532 * </p>
533 *
534 * @param event the current LogEvent, if one exists.
535 * @param source the character array to replace in, not altered, null returns null
536 * @param offset the start offset within the array, must be valid
537 * @param length the length within the array to be processed, must be valid
538 * @return the result of the replace operation
539 */
540 public String replace(final LogEvent event, final char[] source, final int offset, final int length) {
541 if (source == null) {
542 return null;
543 }
544 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
545 substitute(event, buf, 0, length);
546 return buf.toString();
547 }
548
549 //-----------------------------------------------------------------------
550 /**
551 * Replaces all the occurrences of variables with their matching values
552 * from the resolver using the given source buffer as a template.
553 * The buffer is not altered by this method.
554 *
555 * @param source the buffer to use as a template, not changed, null returns null
556 * @return the result of the replace operation
557 */
558 public String replace(final StringBuffer source) {
559 return replace(null, source);
560 }
561
562 //-----------------------------------------------------------------------
563 /**
564 * Replaces all the occurrences of variables with their matching values
565 * from the resolver using the given source buffer as a template.
566 * The buffer is not altered by this method.
567 *
568 * @param event the current LogEvent, if one exists.
569 * @param source the buffer to use as a template, not changed, null returns null
570 * @return the result of the replace operation
571 */
572 public String replace(final LogEvent event, final StringBuffer source) {
573 if (source == null) {
574 return null;
575 }
576 final StringBuilder buf = new StringBuilder(source.length()).append(source);
577 substitute(event, buf, 0, buf.length());
578 return buf.toString();
579 }
580
581 /**
582 * Replaces all the occurrences of variables with their matching values
583 * from the resolver using the given source buffer as a template.
584 * The buffer is not altered by this method.
585 * <p>
586 * Only the specified portion of the buffer will be processed.
587 * The rest of the buffer is not processed, and is not returned.
588 * </p>
589 *
590 * @param source the buffer to use as a template, not changed, null returns null
591 * @param offset the start offset within the array, must be valid
592 * @param length the length within the array to be processed, must be valid
593 * @return the result of the replace operation
594 */
595 public String replace(final StringBuffer source, final int offset, final int length) {
596 return replace(null, source, offset, length);
597 }
598
599 /**
600 * Replaces all the occurrences of variables with their matching values
601 * from the resolver using the given source buffer as a template.
602 * The buffer is not altered by this method.
603 * <p>
604 * Only the specified portion of the buffer will be processed.
605 * The rest of the buffer is not processed, and is not returned.
606 * </p>
607 *
608 * @param event the current LogEvent, if one exists.
609 * @param source the buffer to use as a template, not changed, null returns null
610 * @param offset the start offset within the array, must be valid
611 * @param length the length within the array to be processed, must be valid
612 * @return the result of the replace operation
613 */
614 public String replace(final LogEvent event, final StringBuffer source, final int offset, final int length) {
615 if (source == null) {
616 return null;
617 }
618 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
619 substitute(event, buf, 0, length);
620 return buf.toString();
621 }
622
623 //-----------------------------------------------------------------------
624 /**
625 * Replaces all the occurrences of variables with their matching values
626 * from the resolver using the given source builder as a template.
627 * The builder is not altered by this method.
628 *
629 * @param source the builder to use as a template, not changed, null returns null
630 * @return the result of the replace operation
631 */
632 public String replace(final StringBuilder source) {
633 return replace(null, source);
634 }
635
636 //-----------------------------------------------------------------------
637 /**
638 * Replaces all the occurrences of variables with their matching values
639 * from the resolver using the given source builder as a template.
640 * The builder is not altered by this method.
641 *
642 * @param event The LogEvent.
643 * @param source the builder to use as a template, not changed, null returns null.
644 * @return the result of the replace operation.
645 */
646 public String replace(final LogEvent event, final StringBuilder source) {
647 if (source == null) {
648 return null;
649 }
650 final StringBuilder buf = new StringBuilder(source.length()).append(source);
651 substitute(event, buf, 0, buf.length());
652 return buf.toString();
653 }
654 /**
655 * Replaces all the occurrences of variables with their matching values
656 * from the resolver using the given source builder as a template.
657 * The builder is not altered by this method.
658 * <p>
659 * Only the specified portion of the builder will be processed.
660 * The rest of the builder is not processed, and is not returned.
661 * </p>
662 *
663 * @param source the builder to use as a template, not changed, null returns null
664 * @param offset the start offset within the array, must be valid
665 * @param length the length within the array to be processed, must be valid
666 * @return the result of the replace operation
667 */
668 public String replace(final StringBuilder source, final int offset, final int length) {
669 return replace(null, source, offset, length);
670 }
671
672 /**
673 * Replaces all the occurrences of variables with their matching values
674 * from the resolver using the given source builder as a template.
675 * The builder is not altered by this method.
676 * <p>
677 * Only the specified portion of the builder will be processed.
678 * The rest of the builder is not processed, and is not returned.
679 * </p>
680 *
681 * @param event the current LogEvent, if one exists.
682 * @param source the builder to use as a template, not changed, null returns null
683 * @param offset the start offset within the array, must be valid
684 * @param length the length within the array to be processed, must be valid
685 * @return the result of the replace operation
686 */
687 public String replace(final LogEvent event, final StringBuilder source, final int offset, final int length) {
688 if (source == null) {
689 return null;
690 }
691 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
692 substitute(event, buf, 0, length);
693 return buf.toString();
694 }
695
696 //-----------------------------------------------------------------------
697 /**
698 * Replaces all the occurrences of variables in the given source object with
699 * their matching values from the resolver. The input source object is
700 * converted to a string using <code>toString</code> and is not altered.
701 *
702 * @param source the source to replace in, null returns null
703 * @return the result of the replace operation
704 */
705 public String replace(final Object source) {
706 return replace(null, source);
707 }
708 //-----------------------------------------------------------------------
709 /**
710 * Replaces all the occurrences of variables in the given source object with
711 * their matching values from the resolver. The input source object is
712 * converted to a string using <code>toString</code> and is not altered.
713 *
714 * @param event the current LogEvent, if one exists.
715 * @param source the source to replace in, null returns null
716 * @return the result of the replace operation
717 */
718 public String replace(final LogEvent event, final Object source) {
719 if (source == null) {
720 return null;
721 }
722 final StringBuilder buf = new StringBuilder().append(source);
723 substitute(event, buf, 0, buf.length());
724 return buf.toString();
725 }
726
727 //-----------------------------------------------------------------------
728 /**
729 * Replaces all the occurrences of variables within the given source buffer
730 * with their matching values from the resolver.
731 * The buffer is updated with the result.
732 *
733 * @param source the buffer to replace in, updated, null returns zero
734 * @return true if altered
735 */
736 public boolean replaceIn(final StringBuffer source) {
737 if (source == null) {
738 return false;
739 }
740 return replaceIn(source, 0, source.length());
741 }
742
743 /**
744 * Replaces all the occurrences of variables within the given source buffer
745 * with their matching values from the resolver.
746 * The buffer is updated with the result.
747 * <p>
748 * Only the specified portion of the buffer will be processed.
749 * The rest of the buffer is not processed, but it is not deleted.
750 * </p>
751 *
752 * @param source the buffer to replace in, updated, null returns zero
753 * @param offset the start offset within the array, must be valid
754 * @param length the length within the buffer to be processed, must be valid
755 * @return true if altered
756 */
757 public boolean replaceIn(final StringBuffer source, final int offset, final int length) {
758 return replaceIn(null, source, offset, length);
759 }
760
761 /**
762 * Replaces all the occurrences of variables within the given source buffer
763 * with their matching values from the resolver.
764 * The buffer is updated with the result.
765 * <p>
766 * Only the specified portion of the buffer will be processed.
767 * The rest of the buffer is not processed, but it is not deleted.
768 * </p>
769 *
770 * @param event the current LogEvent, if one exists.
771 * @param source the buffer to replace in, updated, null returns zero
772 * @param offset the start offset within the array, must be valid
773 * @param length the length within the buffer to be processed, must be valid
774 * @return true if altered
775 */
776 public boolean replaceIn(final LogEvent event, final StringBuffer source, final int offset, final int length) {
777 if (source == null) {
778 return false;
779 }
780 final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
781 if (!substitute(event, buf, 0, length)) {
782 return false;
783 }
784 source.replace(offset, offset + length, buf.toString());
785 return true;
786 }
787
788 //-----------------------------------------------------------------------
789 /**
790 * Replaces all the occurrences of variables within the given source
791 * builder with their matching values from the resolver.
792 *
793 * @param source the builder to replace in, updated, null returns zero
794 * @return true if altered
795 */
796 public boolean replaceIn(final StringBuilder source) {
797 return replaceIn(null, source);
798 }
799
800 //-----------------------------------------------------------------------
801 /**
802 * Replaces all the occurrences of variables within the given source
803 * builder with their matching values from the resolver.
804 *
805 * @param event the current LogEvent, if one exists.
806 * @param source the builder to replace in, updated, null returns zero
807 * @return true if altered
808 */
809 public boolean replaceIn(final LogEvent event, final StringBuilder source) {
810 if (source == null) {
811 return false;
812 }
813 return substitute(event, source, 0, source.length());
814 }
815 /**
816 * Replaces all the occurrences of variables within the given source
817 * builder with their matching values from the resolver.
818 * <p>
819 * Only the specified portion of the builder will be processed.
820 * The rest of the builder is not processed, but it is not deleted.
821 * </p>
822 *
823 * @param source the builder to replace in, null returns zero
824 * @param offset the start offset within the array, must be valid
825 * @param length the length within the builder to be processed, must be valid
826 * @return true if altered
827 */
828 public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
829 return replaceIn(null, source, offset, length);
830 }
831
832 /**
833 * Replaces all the occurrences of variables within the given source
834 * builder with their matching values from the resolver.
835 * <p>
836 * Only the specified portion of the builder will be processed.
837 * The rest of the builder is not processed, but it is not deleted.
838 * </p>
839 *
840 * @param event the current LogEvent, if one is present.
841 * @param source the builder to replace in, null returns zero
842 * @param offset the start offset within the array, must be valid
843 * @param length the length within the builder to be processed, must be valid
844 * @return true if altered
845 */
846 public boolean replaceIn(final LogEvent event, final StringBuilder source, final int offset, final int length) {
847 if (source == null) {
848 return false;
849 }
850 return substitute(event, source, offset, length);
851 }
852
853 //-----------------------------------------------------------------------
854 /**
855 * Internal method that substitutes the variables.
856 * <p>
857 * Most users of this class do not need to call this method. This method will
858 * be called automatically by another (public) method.
859 * </p>
860 * <p>
861 * Writers of subclasses can override this method if they need access to
862 * the substitution process at the start or end.
863 * </p>
864 *
865 * @param event The current LogEvent, if there is one.
866 * @param buf the string builder to substitute into, not null
867 * @param offset the start offset within the builder, must be valid
868 * @param length the length within the builder to be processed, must be valid
869 * @return true if altered
870 */
871 protected boolean substitute(final LogEvent event, final StringBuilder buf, final int offset, final int length) {
872 return substitute(event, buf, offset, length, null) > 0;
873 }
874
875 /**
876 * Recursive handler for multiple levels of interpolation. This is the main
877 * interpolation method, which resolves the values of all variable references
878 * contained in the passed in text.
879 *
880 * @param event The current LogEvent, if there is one.
881 * @param buf the string builder to substitute into, not null
882 * @param offset the start offset within the builder, must be valid
883 * @param length the length within the builder to be processed, must be valid
884 * @param priorVariables the stack keeping track of the replaced variables, may be null
885 * @return the length change that occurs, unless priorVariables is null when the int
886 * represents a boolean flag as to whether any change occurred.
887 */
888 private int substitute(final LogEvent event, final StringBuilder buf, final int offset, final int length,
889 List<String> priorVariables) {
890 final StrMatcher prefixMatcher = getVariablePrefixMatcher();
891 final StrMatcher suffixMatcher = getVariableSuffixMatcher();
892 final char escape = getEscapeChar();
893 final StrMatcher valueDelimiterMatcher = getValueDelimiterMatcher();
894 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables();
895
896 final boolean top = priorVariables == null;
897 boolean altered = false;
898 int lengthChange = 0;
899 char[] chars = getChars(buf);
900 int bufEnd = offset + length;
901 int pos = offset;
902 while (pos < bufEnd) {
903 final int startMatchLen = prefixMatcher.isMatch(chars, pos, offset, bufEnd);
904 if (startMatchLen == 0) {
905 pos++;
906 } else {
907 // found variable start marker
908 if (pos > offset && chars[pos - 1] == escape) {
909 // escaped
910 buf.deleteCharAt(pos - 1);
911 chars = getChars(buf);
912 lengthChange--;
913 altered = true;
914 bufEnd--;
915 } else {
916 // find suffix
917 final int startPos = pos;
918 pos += startMatchLen;
919 int endMatchLen = 0;
920 int nestedVarCount = 0;
921 while (pos < bufEnd) {
922 if (substitutionInVariablesEnabled
923 && (endMatchLen = prefixMatcher.isMatch(chars, pos, offset, bufEnd)) != 0) {
924 // found a nested variable start
925 nestedVarCount++;
926 pos += endMatchLen;
927 continue;
928 }
929
930 endMatchLen = suffixMatcher.isMatch(chars, pos, offset, bufEnd);
931 if (endMatchLen == 0) {
932 pos++;
933 } else {
934 // found variable end marker
935 if (nestedVarCount == 0) {
936 String varNameExpr = new String(chars, startPos + startMatchLen, pos - startPos - startMatchLen);
937 if (substitutionInVariablesEnabled) {
938 final StringBuilder bufName = new StringBuilder(varNameExpr);
939 substitute(event, bufName, 0, bufName.length());
940 varNameExpr = bufName.toString();
941 }
942 pos += endMatchLen;
943 final int endPos = pos;
944
945 String varName = varNameExpr;
946 String varDefaultValue = null;
947
948 if (valueDelimiterMatcher != null) {
949 final char [] varNameExprChars = varNameExpr.toCharArray();
950 int valueDelimiterMatchLen = 0;
951 for (int i = 0; i < varNameExprChars.length; i++) {
952 // if there's any nested variable when nested variable substitution disabled, then stop resolving name and default value.
953 if (!substitutionInVariablesEnabled
954 && prefixMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) {
955 break;
956 }
957 if ((valueDelimiterMatchLen = valueDelimiterMatcher.isMatch(varNameExprChars, i)) != 0) {
958 varName = varNameExpr.substring(0, i);
959 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
960 break;
961 }
962 }
963 }
964
965 // on the first call initialize priorVariables
966 if (priorVariables == null) {
967 priorVariables = new ArrayList<>();
968 priorVariables.add(new String(chars, offset, length + lengthChange));
969 }
970
971 // handle cyclic substitution
972 checkCyclicSubstitution(varName, priorVariables);
973 priorVariables.add(varName);
974
975 // resolve the variable
976 String varValue = resolveVariable(event, varName, buf, startPos, endPos);
977 if (varValue == null) {
978 varValue = varDefaultValue;
979 }
980 if (varValue != null) {
981 // recursive replace
982 final int varLen = varValue.length();
983 buf.replace(startPos, endPos, varValue);
984 altered = true;
985 int change = substitute(event, buf, startPos, varLen, priorVariables);
986 change = change + (varLen - (endPos - startPos));
987 pos += change;
988 bufEnd += change;
989 lengthChange += change;
990 chars = getChars(buf); // in case buffer was altered
991 }
992
993 // remove variable from the cyclic stack
994 priorVariables.remove(priorVariables.size() - 1);
995 break;
996 }
997 nestedVarCount--;
998 pos += endMatchLen;
999 }
1000 }
1001 }
1002 }
1003 }
1004 if (top) {
1005 return altered ? 1 : 0;
1006 }
1007 return lengthChange;
1008 }
1009
1010 /**
1011 * Checks if the specified variable is already in the stack (list) of variables.
1012 *
1013 * @param varName the variable name to check
1014 * @param priorVariables the list of prior variables
1015 */
1016 private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) {
1017 if (!priorVariables.contains(varName)) {
1018 return;
1019 }
1020 final StringBuilder buf = new StringBuilder(BUF_SIZE);
1021 buf.append("Infinite loop in property interpolation of ");
1022 buf.append(priorVariables.remove(0));
1023 buf.append(": ");
1024 appendWithSeparators(buf, priorVariables, "->");
1025 throw new IllegalStateException(buf.toString());
1026 }
1027
1028 /**
1029 * Internal method that resolves the value of a variable.
1030 * <p>
1031 * Most users of this class do not need to call this method. This method is
1032 * called automatically by the substitution process.
1033 * </p>
1034 * <p>
1035 * Writers of subclasses can override this method if they need to alter
1036 * how each substitution occurs. The method is passed the variable's name
1037 * and must return the corresponding value. This implementation uses the
1038 * {@link #getVariableResolver()} with the variable's name as the key.
1039 * </p>
1040 *
1041 * @param event The LogEvent, if there is one.
1042 * @param variableName the name of the variable, not null
1043 * @param buf the buffer where the substitution is occurring, not null
1044 * @param startPos the start position of the variable including the prefix, valid
1045 * @param endPos the end position of the variable including the suffix, valid
1046 * @return the variable's value or <b>null</b> if the variable is unknown
1047 */
1048 protected String resolveVariable(final LogEvent event, final String variableName, final StringBuilder buf,
1049 final int startPos, final int endPos) {
1050 final StrLookup resolver = getVariableResolver();
1051 if (resolver == null) {
1052 return null;
1053 }
1054 return resolver.lookup(event, variableName);
1055 }
1056
1057 // Escape
1058 //-----------------------------------------------------------------------
1059 /**
1060 * Returns the escape character.
1061 *
1062 * @return the character used for escaping variable references
1063 */
1064 public char getEscapeChar() {
1065 return this.escapeChar;
1066 }
1067
1068 /**
1069 * Sets the escape character.
1070 * If this character is placed before a variable reference in the source
1071 * text, this variable will be ignored.
1072 *
1073 * @param escapeCharacter the escape character (0 for disabling escaping)
1074 */
1075 public void setEscapeChar(final char escapeCharacter) {
1076 this.escapeChar = escapeCharacter;
1077 }
1078
1079 // Prefix
1080 //-----------------------------------------------------------------------
1081 /**
1082 * Gets the variable prefix matcher currently in use.
1083 * <p>
1084 * The variable prefix is the character or characters that identify the
1085 * start of a variable. This prefix is expressed in terms of a matcher
1086 * allowing advanced prefix matches.
1087 * </p>
1088 *
1089 * @return the prefix matcher in use
1090 */
1091 public StrMatcher getVariablePrefixMatcher() {
1092 return prefixMatcher;
1093 }
1094
1095 /**
1096 * Sets the variable prefix matcher currently in use.
1097 * <p>
1098 * The variable prefix is the character or characters that identify the
1099 * start of a variable. This prefix is expressed in terms of a matcher
1100 * allowing advanced prefix matches.
1101 * </p>
1102 *
1103 * @param prefixMatcher the prefix matcher to use, null ignored
1104 * @return this, to enable chaining
1105 * @throws IllegalArgumentException if the prefix matcher is null
1106 */
1107 public StrSubstitutor setVariablePrefixMatcher(final StrMatcher prefixMatcher) {
1108 if (prefixMatcher == null) {
1109 throw new IllegalArgumentException("Variable prefix matcher must not be null!");
1110 }
1111 this.prefixMatcher = prefixMatcher;
1112 return this;
1113 }
1114
1115 /**
1116 * Sets the variable prefix to use.
1117 * <p>
1118 * The variable prefix is the character or characters that identify the
1119 * start of a variable. This method allows a single character prefix to
1120 * be easily set.
1121 * </p>
1122 *
1123 * @param prefix the prefix character to use
1124 * @return this, to enable chaining
1125 */
1126 public StrSubstitutor setVariablePrefix(final char prefix) {
1127 return setVariablePrefixMatcher(StrMatcher.charMatcher(prefix));
1128 }
1129
1130 /**
1131 * Sets the variable prefix to use.
1132 * <p>
1133 * The variable prefix is the character or characters that identify the
1134 * start of a variable. This method allows a string prefix to be easily set.
1135 * </p>
1136 *
1137 * @param prefix the prefix for variables, not null
1138 * @return this, to enable chaining
1139 * @throws IllegalArgumentException if the prefix is null
1140 */
1141 public StrSubstitutor setVariablePrefix(final String prefix) {
1142 if (prefix == null) {
1143 throw new IllegalArgumentException("Variable prefix must not be null!");
1144 }
1145 return setVariablePrefixMatcher(StrMatcher.stringMatcher(prefix));
1146 }
1147
1148 // Suffix
1149 //-----------------------------------------------------------------------
1150 /**
1151 * Gets the variable suffix matcher currently in use.
1152 * <p>
1153 * The variable suffix is the character or characters that identify the
1154 * end of a variable. This suffix is expressed in terms of a matcher
1155 * allowing advanced suffix matches.
1156 * </p>
1157 *
1158 * @return the suffix matcher in use
1159 */
1160 public StrMatcher getVariableSuffixMatcher() {
1161 return suffixMatcher;
1162 }
1163
1164 /**
1165 * Sets the variable suffix matcher currently in use.
1166 * <p>
1167 * The variable suffix is the character or characters that identify the
1168 * end of a variable. This suffix is expressed in terms of a matcher
1169 * allowing advanced suffix matches.
1170 * </p>
1171 *
1172 * @param suffixMatcher the suffix matcher to use, null ignored
1173 * @return this, to enable chaining
1174 * @throws IllegalArgumentException if the suffix matcher is null
1175 */
1176 public StrSubstitutor setVariableSuffixMatcher(final StrMatcher suffixMatcher) {
1177 if (suffixMatcher == null) {
1178 throw new IllegalArgumentException("Variable suffix matcher must not be null!");
1179 }
1180 this.suffixMatcher = suffixMatcher;
1181 return this;
1182 }
1183
1184 /**
1185 * Sets the variable suffix to use.
1186 * <p>
1187 * The variable suffix is the character or characters that identify the
1188 * end of a variable. This method allows a single character suffix to
1189 * be easily set.
1190 * </p>
1191 *
1192 * @param suffix the suffix character to use
1193 * @return this, to enable chaining
1194 */
1195 public StrSubstitutor setVariableSuffix(final char suffix) {
1196 return setVariableSuffixMatcher(StrMatcher.charMatcher(suffix));
1197 }
1198
1199 /**
1200 * Sets the variable suffix to use.
1201 * <p>
1202 * The variable suffix is the character or characters that identify the
1203 * end of a variable. This method allows a string suffix to be easily set.
1204 * </p>
1205 *
1206 * @param suffix the suffix for variables, not null
1207 * @return this, to enable chaining
1208 * @throws IllegalArgumentException if the suffix is null
1209 */
1210 public StrSubstitutor setVariableSuffix(final String suffix) {
1211 if (suffix == null) {
1212 throw new IllegalArgumentException("Variable suffix must not be null!");
1213 }
1214 return setVariableSuffixMatcher(StrMatcher.stringMatcher(suffix));
1215 }
1216
1217 // Variable Default Value Delimiter
1218 //-----------------------------------------------------------------------
1219 /**
1220 * Gets the variable default value delimiter matcher currently in use.
1221 * <p>
1222 * The variable default value delimiter is the character or characters that delimit the
1223 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
1224 * allowing advanced variable default value delimiter matches.
1225 * </p>
1226 * <p>
1227 * If it returns null, then the variable default value resolution is disabled.
1228 * </p>
1229 *
1230 * @return the variable default value delimiter matcher in use, may be null
1231 */
1232 public StrMatcher getValueDelimiterMatcher() {
1233 return valueDelimiterMatcher;
1234 }
1235
1236 /**
1237 * Sets the variable default value delimiter matcher to use.
1238 * <p>
1239 * The variable default value delimiter is the character or characters that delimit the
1240 * variable name and the variable default value. This delimiter is expressed in terms of a matcher
1241 * allowing advanced variable default value delimiter matches.
1242 * </p>
1243 * <p>
1244 * If the <code>valueDelimiterMatcher</code> is null, then the variable default value resolution
1245 * becomes disabled.
1246 * </p>
1247 *
1248 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null
1249 * @return this, to enable chaining
1250 */
1251 public StrSubstitutor setValueDelimiterMatcher(final StrMatcher valueDelimiterMatcher) {
1252 this.valueDelimiterMatcher = valueDelimiterMatcher;
1253 return this;
1254 }
1255
1256 /**
1257 * Sets the variable default value delimiter to use.
1258 * <p>
1259 * The variable default value delimiter is the character or characters that delimit the
1260 * variable name and the variable default value. This method allows a single character
1261 * variable default value delimiter to be easily set.
1262 * </p>
1263 *
1264 * @param valueDelimiter the variable default value delimiter character to use
1265 * @return this, to enable chaining
1266 */
1267 public StrSubstitutor setValueDelimiter(final char valueDelimiter) {
1268 return setValueDelimiterMatcher(StrMatcher.charMatcher(valueDelimiter));
1269 }
1270
1271 /**
1272 * Sets the variable default value delimiter to use.
1273 * <p>
1274 * The variable default value delimiter is the character or characters that delimit the
1275 * variable name and the variable default value. This method allows a string
1276 * variable default value delimiter to be easily set.
1277 * </p>
1278 * <p>
1279 * If the <code>valueDelimiter</code> is null or empty string, then the variable default
1280 * value resolution becomes disabled.
1281 * </p>
1282 *
1283 * @param valueDelimiter the variable default value delimiter string to use, may be null or empty
1284 * @return this, to enable chaining
1285 */
1286 public StrSubstitutor setValueDelimiter(final String valueDelimiter) {
1287 if (Strings.isEmpty(valueDelimiter)) {
1288 setValueDelimiterMatcher(null);
1289 return this;
1290 }
1291 return setValueDelimiterMatcher(StrMatcher.stringMatcher(valueDelimiter));
1292 }
1293
1294 // Resolver
1295 //-----------------------------------------------------------------------
1296 /**
1297 * Gets the VariableResolver that is used to lookup variables.
1298 *
1299 * @return the VariableResolver
1300 */
1301 public StrLookup getVariableResolver() {
1302 return this.variableResolver;
1303 }
1304
1305 /**
1306 * Sets the VariableResolver that is used to lookup variables.
1307 *
1308 * @param variableResolver the VariableResolver
1309 */
1310 public void setVariableResolver(final StrLookup variableResolver) {
1311 if (variableResolver instanceof ConfigurationAware && this.configuration != null) {
1312 ((ConfigurationAware) variableResolver).setConfiguration(this.configuration);
1313 }
1314 this.variableResolver = variableResolver;
1315 }
1316
1317 // Substitution support in variable names
1318 //-----------------------------------------------------------------------
1319 /**
1320 * Returns a flag whether substitution is done in variable names.
1321 *
1322 * @return the substitution in variable names flag
1323 */
1324 public boolean isEnableSubstitutionInVariables() {
1325 return enableSubstitutionInVariables;
1326 }
1327
1328 /**
1329 * Sets a flag whether substitution is done in variable names. If set to
1330 * <b>true</b>, the names of variables can contain other variables which are
1331 * processed first before the original variable is evaluated, e.g.
1332 * <code>${jre-${java.version}}</code>. The default value is <b>true</b>.
1333 *
1334 * @param enableSubstitutionInVariables the new value of the flag
1335 */
1336 public void setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) {
1337 this.enableSubstitutionInVariables = enableSubstitutionInVariables;
1338 }
1339
1340 private char[] getChars(final StringBuilder sb) {
1341 final char[] chars = new char[sb.length()];
1342 sb.getChars(0, sb.length(), chars, 0);
1343 return chars;
1344 }
1345
1346 /**
1347 * Appends a iterable placing separators between each value, but
1348 * not before the first or after the last.
1349 * Appending a null iterable will have no effect..
1350 *
1351 * @param sb StringBuilder that contains the String being constructed.
1352 * @param iterable the iterable to append
1353 * @param separator the separator to use, null means no separator
1354 */
1355 public void appendWithSeparators(final StringBuilder sb, final Iterable<?> iterable, String separator) {
1356 if (iterable != null) {
1357 separator = separator == null ? Strings.EMPTY : separator;
1358 final Iterator<?> it = iterable.iterator();
1359 while (it.hasNext()) {
1360 sb.append(it.next());
1361 if (it.hasNext()) {
1362 sb.append(separator);
1363 }
1364 }
1365 }
1366 }
1367
1368 @Override
1369 public String toString() {
1370 return "StrSubstitutor(" + variableResolver.toString() + ')';
1371 }
1372
1373 @Override
1374 public void setConfiguration(final Configuration configuration) {
1375 this.configuration = configuration;
1376 if (this.variableResolver instanceof ConfigurationAware) {
1377 ((ConfigurationAware) this.variableResolver).setConfiguration(this.configuration);
1378 }
1379 }
1380 }