001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * https://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.text; 018 019import java.util.ArrayList; 020import java.util.List; 021import java.util.Map; 022import java.util.Objects; 023import java.util.Properties; 024import java.util.function.Function; 025import java.util.stream.Collectors; 026 027import org.apache.commons.lang3.Validate; 028import org.apache.commons.text.lookup.StringLookup; 029import org.apache.commons.text.lookup.StringLookupFactory; 030import org.apache.commons.text.matcher.StringMatcher; 031import org.apache.commons.text.matcher.StringMatcherFactory; 032 033/** 034 * Substitutes variables within a string by values. 035 * <p> 036 * This class takes a piece of text and substitutes all the variables within it. The default definition of a variable is 037 * {@code ${variableName}}. The prefix and suffix can be changed via constructors and set methods. 038 * </p> 039 * <p> 040 * Variable values are typically resolved from a map, but could also be resolved from system properties, or by supplying 041 * a custom variable resolver. 042 * </p> 043 * <h2>Using System Properties</h2> 044 * <p> 045 * The simplest example is to use this class to replace Java System properties. For example: 046 * </p> 047 * 048 * <pre> 049 * StringSubstitutor 050 * .replaceSystemProperties("You are running with java.version = ${java.version} and os.name = ${os.name}."); 051 * </pre> 052 * 053 * <h2>Using a Custom Map</h2> 054 * <p> 055 * Typical usage of this class follows the following pattern: 056 * </p> 057 * <ul> 058 * <li>Create and initialize a StringSubstitutor with the map that contains the values for the variables you want to 059 * make available.</li> 060 * <li>Optionally set attributes like variable prefix, variable suffix, default value delimiter, and so on.</li> 061 * <li>Call the {@code replace()} method with in the source text for interpolation.</li> 062 * <li>The returned text contains all variable references (as long as their values are known) as resolved.</li> 063 * </ul> 064 * <p> 065 * For example: 066 * </p> 067 * 068 * <pre> 069 * // Build map 070 * Map<String, String> valuesMap = new HashMap<>(); 071 * valuesMap.put("animal", "quick brown fox"); 072 * valuesMap.put("target", "lazy dog"); 073 * String templateString = "The ${animal} jumped over the ${target}."; 074 * 075 * // Build StringSubstitutor 076 * StringSubstitutor sub = new StringSubstitutor(valuesMap); 077 * 078 * // Replace 079 * String resolvedString = sub.replace(templateString); 080 * </pre> 081 * 082 * <p> 083 * yielding: 084 * </p> 085 * 086 * <pre> 087 * "The quick brown fox jumped over the lazy dog." 088 * </pre> 089 * 090 * <h2>Providing Default Values</h2> 091 * <p> 092 * You can set a default value for unresolved variables. The default value for a variable can be appended to the 093 * variable name after the variable default value delimiter. The default value of the variable default value delimiter 094 * is ":-", as in bash and other *nix shells. 095 * </p> 096 * <p> 097 * You can set the variable value delimiter with {@link #setValueDelimiterMatcher(StringMatcher)}, 098 * {@link #setValueDelimiter(char)} or {@link #setValueDelimiter(String)}. 099 * </p> 100 * <p> 101 * For example: 102 * </p> 103 * 104 * <pre> 105 * // Build map 106 * Map<String, String> valuesMap = new HashMap<>(); 107 * valuesMap.put("animal", "quick brown fox"); 108 * valuesMap.put("target", "lazy dog"); 109 * String templateString = "The ${animal} jumped over the ${target} ${undefined.number:-1234567890} times."; 110 * 111 * // Build StringSubstitutor 112 * StringSubstitutor sub = new StringSubstitutor(valuesMap); 113 * 114 * // Replace 115 * String resolvedString = sub.replace(templateString); 116 * </pre> 117 * 118 * <p> 119 * yielding: 120 * </p> 121 * 122 * <pre> 123 * "The quick brown fox jumped over the lazy dog 1234567890 times." 124 * </pre> 125 * 126 * <p> 127 * {@code StringSubstitutor} supports throwing exceptions for unresolved variables, you enable this by setting calling 128 * {@link #setEnableUndefinedVariableException(boolean)} with {@code true}. 129 * </p> 130 * 131 * <h2>Reusing Instances</h2> 132 * <p> 133 * Static shortcut methods cover the most common use cases. If multiple replace operations are to be performed, creating 134 * and reusing an instance of this class will be more efficient. 135 * </p> 136 * 137 * <h2>Using Interpolation</h2> 138 * <p> 139 * The default interpolator lets you use string lookups like: 140 * </p> 141 * 142 * <pre> 143 * final StringSubstitutor interpolator = StringSubstitutor.createInterpolator(); 144 * final String text = interpolator.replace( 145 * "Base64 Decoder: ${base64Decoder:SGVsbG9Xb3JsZCE=}\n" 146 * + "Base64 Encoder: ${base64Encoder:HelloWorld!}\n" 147 * + "Java Constant: ${const:java.awt.event.KeyEvent.VK_ESCAPE}\n" 148 * + "Date: ${date:yyyy-MM-dd}\n" 149 * + "Environment Variable: ${env:USERNAME}\n" 150 * + "File Content: ${file:UTF-8:src/test/resources/document.properties}\n" 151 * + "Java: ${java:version}\n" 152 * + "Localhost: ${localhost:canonical-name}\n" 153 * + "Properties File: ${properties:src/test/resources/document.properties::mykey}\n" 154 * + "Resource Bundle: ${resourceBundle:org.apache.commons.text.example.testResourceBundleLookup:mykey}\n" 155 * + "System Property: ${sys:user.dir}\n" 156 * + "URL Decoder: ${urlDecoder:Hello%20World%21}\n" 157 * + "URL Encoder: ${urlEncoder:Hello World!}\n" 158 * + "XML XPath: ${xml:src/test/resources/document.xml:/root/path/to/node}\n"); 159 * </pre> 160 * <p> 161 * For documentation and a full list of available lookups, see {@link StringLookupFactory}. 162 * </p> 163 * <p><strong>NOTE:</strong> The list of lookups available by default in {@link #createInterpolator()} changed 164 * in version {@code 1.10.0}. See the {@link StringLookupFactory} documentation for details and an explanation 165 * on how to reproduce the previous functionality. 166 * </p> 167 * 168 * <h2>Using Recursive Variable Replacement</h2> 169 * <p> 170 * Variable replacement can work recursively by calling {@link #setEnableSubstitutionInVariables(boolean)} with 171 * {@code true}. If a variable value contains a variable then that variable will also be replaced. Cyclic replacements 172 * are detected and will throw an exception. 173 * </p> 174 * <p> 175 * You can get the replace result to contain a variable prefix. For example: 176 * </p> 177 * 178 * <pre> 179 * "The variable ${${name}} must be used." 180 * </pre> 181 * 182 * <p> 183 * If the value of the "name" variable is "x", then only the variable "name" is replaced resulting in: 184 * </p> 185 * 186 * <pre> 187 * "The variable ${x} must be used." 188 * </pre> 189 * 190 * <p> 191 * To achieve this effect there are two possibilities: Either set a different prefix and suffix for variables which do 192 * not conflict with the result text you want to produce. The other possibility is to use the escape character, by 193 * default '$'. If this character is placed before a variable reference, this reference is ignored and won't be 194 * replaced. For example: 195 * </p> 196 * 197 * <pre> 198 * "The variable $${${name}} must be used." 199 * </pre> 200 * <p> 201 * In some complex scenarios you might even want to perform substitution in the names of variables, for instance 202 * </p> 203 * 204 * <pre> 205 * ${jre-${java.specification.version}} 206 * </pre> 207 * 208 * <p> 209 * {@code StringSubstitutor} supports this recursive substitution in variable names, but it has to be enabled explicitly 210 * by calling {@link #setEnableSubstitutionInVariables(boolean)} with {@code true}. 211 * </p> 212 * 213 * <h2>Thread Safety</h2> 214 * <p> 215 * This class is <strong>not</strong> thread safe. 216 * </p> 217 * 218 * @since 1.3 219 */ 220public class StringSubstitutor { 221 222 /** 223 * The low-level result of a substitution. 224 * 225 * @since 1.9 226 */ 227 private static final class Result { 228 229 /** Whether the buffer is altered. */ 230 public final boolean altered; 231 232 /** The length of change. */ 233 public final int lengthChange; 234 235 private Result(final boolean altered, final int lengthChange) { 236 this.altered = altered; 237 this.lengthChange = lengthChange; 238 } 239 240 @Override 241 public String toString() { 242 return "Result [altered=" + altered + ", lengthChange=" + lengthChange + "]"; 243 } 244 } 245 246 /** 247 * Constant for the default escape character. 248 */ 249 public static final char DEFAULT_ESCAPE = '$'; 250 251 /** 252 * The default variable default separator. 253 * 254 * @since 1.5. 255 */ 256 public static final String DEFAULT_VAR_DEFAULT = ":-"; 257 258 /** 259 * The default variable end separator. 260 * 261 * @since 1.5. 262 */ 263 public static final String DEFAULT_VAR_END = "}"; 264 265 /** 266 * The default variable start separator. 267 * 268 * @since 1.5. 269 */ 270 public static final String DEFAULT_VAR_START = "${"; 271 272 /** 273 * Constant for the default variable prefix. 274 */ 275 public static final StringMatcher DEFAULT_PREFIX = StringMatcherFactory.INSTANCE.stringMatcher(DEFAULT_VAR_START); 276 277 /** 278 * Constant for the default variable suffix. 279 */ 280 public static final StringMatcher DEFAULT_SUFFIX = StringMatcherFactory.INSTANCE.stringMatcher(DEFAULT_VAR_END); 281 282 /** 283 * Constant for the default value delimiter of a variable. 284 */ 285 public static final StringMatcher DEFAULT_VALUE_DELIMITER = StringMatcherFactory.INSTANCE 286 .stringMatcher(DEFAULT_VAR_DEFAULT); 287 288 /** 289 * Creates a new instance using the interpolator string lookup 290 * {@link StringLookupFactory#interpolatorStringLookup()}. 291 * <p> 292 * This StringSubstitutor lets you perform substitutions like: 293 * </p> 294 * 295 * <pre> 296 * StringSubstitutor.createInterpolator().replace( 297 * "OS name: ${sys:os.name}, user: ${env:USER}"); 298 * </pre> 299 * 300 * <p>The table below lists the lookups available by default in the returned instance. These 301 * may be modified through the use of the 302 * {@value org.apache.commons.text.lookup.StringLookupFactory#DEFAULT_STRING_LOOKUPS_PROPERTY} 303 * system property, as described in the {@link StringLookupFactory} documentation.</p> 304 * 305 * <p><strong>NOTE:</strong> The list of lookups available by default changed in version {@code 1.10.0}. 306 * Configuration via system property (as mentioned above) may be necessary to reproduce previous functionality. 307 * </p> 308 * 309 * <table> 310 * <caption>Default Lookups</caption> 311 * <tr> 312 * <th>Key</th> 313 * <th>Lookup</th> 314 * </tr> 315 * <tr> 316 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_BASE64_DECODER}</td> 317 * <td>{@link StringLookupFactory#base64DecoderStringLookup()}</td> 318 * </tr> 319 * <tr> 320 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_BASE64_ENCODER}</td> 321 * <td>{@link StringLookupFactory#base64EncoderStringLookup()}</td> 322 * </tr> 323 * <tr> 324 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_CONST}</td> 325 * <td>{@link StringLookupFactory#constantStringLookup()}</td> 326 * </tr> 327 * <tr> 328 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_DATE}</td> 329 * <td>{@link StringLookupFactory#dateStringLookup()}</td> 330 * </tr> 331 * <tr> 332 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_ENV}</td> 333 * <td>{@link StringLookupFactory#environmentVariableStringLookup()}</td> 334 * </tr> 335 * <tr> 336 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_FILE}</td> 337 * <td>{@link StringLookupFactory#fileStringLookup()}</td> 338 * </tr> 339 * <tr> 340 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_JAVA}</td> 341 * <td>{@link StringLookupFactory#javaPlatformStringLookup()}</td> 342 * </tr> 343 * <tr> 344 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_LOCALHOST}</td> 345 * <td>{@link StringLookupFactory#localHostStringLookup()}</td> 346 * </tr> 347 * <tr> 348 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_LOOPBACK_ADDRESS}</td> 349 * <td>{@link StringLookupFactory#loopbackAddressStringLookup()}</td> 350 * </tr> 351 * <tr> 352 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_PROPERTIES}</td> 353 * <td>{@link StringLookupFactory#propertiesStringLookup()}</td> 354 * </tr> 355 * <tr> 356 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_RESOURCE_BUNDLE}</td> 357 * <td>{@link StringLookupFactory#resourceBundleStringLookup()}</td> 358 * </tr> 359 * <tr> 360 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_SYS}</td> 361 * <td>{@link StringLookupFactory#systemPropertyStringLookup()}</td> 362 * </tr> 363 * <tr> 364 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_URL_DECODER}</td> 365 * <td>{@link StringLookupFactory#urlDecoderStringLookup()}</td> 366 * </tr> 367 * <tr> 368 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_URL_ENCODER}</td> 369 * <td>{@link StringLookupFactory#urlEncoderStringLookup()}</td> 370 * </tr> 371 * <tr> 372 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_XML}</td> 373 * <td>{@link StringLookupFactory#xmlStringLookup()}</td> 374 * </tr> 375 * <tr> 376 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_XML_DECODER}</td> 377 * <td>{@link StringLookupFactory#xmlDecoderStringLookup()}</td> 378 * </tr> 379 * <tr> 380 * <td>{@value org.apache.commons.text.lookup.StringLookupFactory#KEY_XML_ENCODER}</td> 381 * <td>{@link StringLookupFactory#xmlEncoderStringLookup()}</td> 382 * </tr> 383 * </table> 384 * 385 * @return a new instance using the interpolator string lookup. 386 * @see StringLookupFactory#interpolatorStringLookup() 387 * @since 1.8 388 */ 389 public static StringSubstitutor createInterpolator() { 390 return new StringSubstitutor(StringLookupFactory.INSTANCE.interpolatorStringLookup()); 391 } 392 393 /** 394 * Replaces all the occurrences of variables in the given source object with their matching values from the map. 395 * 396 * @param <V> the type of the values in the map 397 * @param source the source text containing the variables to substitute, null returns null 398 * @param valueMap the map with the values, may be null 399 * @return The result of the replace operation 400 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true 401 */ 402 public static <V> String replace(final Object source, final Map<String, V> valueMap) { 403 return new StringSubstitutor(valueMap).replace(source); 404 } 405 406 /** 407 * Replaces all the occurrences of variables in the given source object with their matching values from the map. 408 * This method allows to specify a custom variable prefix and suffix 409 * 410 * @param <V> the type of the values in the map 411 * @param source the source text containing the variables to substitute, null returns null 412 * @param valueMap the map with the values, may be null 413 * @param prefix the prefix of variables, not null 414 * @param suffix the suffix of variables, not null 415 * @return The result of the replace operation 416 * @throws IllegalArgumentException if the prefix or suffix is null 417 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true 418 */ 419 public static <V> String replace(final Object source, final Map<String, V> valueMap, final String prefix, 420 final String suffix) { 421 return new StringSubstitutor(valueMap, prefix, suffix).replace(source); 422 } 423 424 /** 425 * Replaces all the occurrences of variables in the given source object with their matching values from the 426 * properties. 427 * 428 * @param source the source text containing the variables to substitute, null returns null 429 * @param valueProperties the properties with values, may be null 430 * @return The result of the replace operation 431 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true 432 */ 433 public static String replace(final Object source, final Properties valueProperties) { 434 if (valueProperties == null) { 435 return source.toString(); 436 } 437 return replace(source, valueProperties.stringPropertyNames().stream().collect(Collectors.toMap(Function.identity(), valueProperties::getProperty))); 438 } 439 440 /** 441 * Replaces all the occurrences of variables in the given source object with their matching values from the system 442 * properties. 443 * 444 * @param source the source text containing the variables to substitute, null returns null 445 * @return The result of the replace operation 446 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true 447 */ 448 public static String replaceSystemProperties(final Object source) { 449 return new StringSubstitutor(StringLookupFactory.INSTANCE.systemPropertyStringLookup()).replace(source); 450 } 451 452 /** 453 * The flag whether substitution in variable values is disabled. 454 */ 455 private boolean disableSubstitutionInValues; 456 457 /** 458 * The flag whether substitution in variable names is enabled. 459 */ 460 private boolean enableSubstitutionInVariables; 461 462 /** 463 * The flag whether exception should be thrown on undefined variable. 464 */ 465 private boolean failOnUndefinedVariable; 466 467 /** 468 * Stores the escape character. 469 */ 470 private char escapeChar; 471 472 /** 473 * Stores the variable prefix. 474 */ 475 private StringMatcher prefixMatcher; 476 477 /** 478 * Whether escapes should be preserved. Default is false; 479 */ 480 private boolean preserveEscapes; 481 482 /** 483 * Stores the variable suffix. 484 */ 485 private StringMatcher suffixMatcher; 486 487 /** 488 * Stores the default variable value delimiter. 489 */ 490 private StringMatcher valueDelimiterMatcher; 491 492 /** 493 * Variable resolution is delegated to an implementor of {@link StringLookup}. 494 */ 495 private StringLookup variableResolver; 496 497 /** 498 * Constructs a new instance with defaults for variable prefix and suffix and the escaping character. 499 */ 500 public StringSubstitutor() { 501 this(null, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE); 502 } 503 504 /** 505 * Constructs a new initialized instance. Uses defaults for variable prefix and suffix and the escaping 506 * character. 507 * 508 * @param <V> the type of the values in the map. 509 * @param valueMap the map with the variables' values, may be null. 510 */ 511 public <V> StringSubstitutor(final Map<String, V> valueMap) { 512 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE); 513 } 514 515 /** 516 * Constructs a new initialized instance. Uses a default escaping character. 517 * 518 * @param <V> the type of the values in the map. 519 * @param valueMap the map with the variables' values, may be null. 520 * @param prefix the prefix for variables, not null. 521 * @param suffix the suffix for variables, not null. 522 * @throws IllegalArgumentException if the prefix or suffix is null. 523 */ 524 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix) { 525 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, DEFAULT_ESCAPE); 526 } 527 528 /** 529 * Constructs a new initialized instance. 530 * 531 * @param <V> the type of the values in the map. 532 * @param valueMap the map with the variables' values, may be null. 533 * @param prefix the prefix for variables, not null. 534 * @param suffix the suffix for variables, not null. 535 * @param escape the escape character. 536 * @throws IllegalArgumentException if the prefix or suffix is null. 537 */ 538 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix, 539 final char escape) { 540 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, escape); 541 } 542 543 /** 544 * Constructs a new initialized instance. 545 * 546 * @param <V> the type of the values in the map. 547 * @param valueMap the map with the variables' values, may be null. 548 * @param prefix the prefix for variables, not null. 549 * @param suffix the suffix for variables, not null. 550 * @param escape the escape character. 551 * @param valueDelimiter the variable default value delimiter, may be null. 552 * @throws IllegalArgumentException if the prefix or suffix is null. 553 */ 554 public <V> StringSubstitutor(final Map<String, V> valueMap, final String prefix, final String suffix, 555 final char escape, final String valueDelimiter) { 556 this(StringLookupFactory.INSTANCE.mapStringLookup(valueMap), prefix, suffix, escape, valueDelimiter); 557 } 558 559 /** 560 * Constructs a new initialized instance. 561 * 562 * @param variableResolver the variable resolver, may be null 563 */ 564 public StringSubstitutor(final StringLookup variableResolver) { 565 this(variableResolver, DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_ESCAPE); 566 } 567 568 /** 569 * Constructs a new initialized instance. 570 * 571 * @param variableResolver the variable resolver, may be null. 572 * @param prefix the prefix for variables, not null. 573 * @param suffix the suffix for variables, not null. 574 * @param escape the escape character. 575 * @throws IllegalArgumentException if the prefix or suffix is null. 576 */ 577 public StringSubstitutor(final StringLookup variableResolver, final String prefix, final String suffix, 578 final char escape) { 579 setVariableResolver(variableResolver); 580 setVariablePrefix(prefix); 581 setVariableSuffix(suffix); 582 setEscapeChar(escape); 583 setValueDelimiterMatcher(DEFAULT_VALUE_DELIMITER); 584 } 585 586 /** 587 * Constructs a new initialized instance. 588 * 589 * @param variableResolver the variable resolver, may be null. 590 * @param prefix the prefix for variables, not null. 591 * @param suffix the suffix for variables, not null. 592 * @param escape the escape character. 593 * @param valueDelimiter the variable default value delimiter string, may be null. 594 * @throws IllegalArgumentException if the prefix or suffix is null. 595 */ 596 public StringSubstitutor(final StringLookup variableResolver, final String prefix, final String suffix, 597 final char escape, final String valueDelimiter) { 598 setVariableResolver(variableResolver); 599 setVariablePrefix(prefix); 600 setVariableSuffix(suffix); 601 setEscapeChar(escape); 602 setValueDelimiter(valueDelimiter); 603 } 604 605 /** 606 * Constructs a new initialized instance. 607 * 608 * @param variableResolver the variable resolver, may be null 609 * @param prefixMatcher the prefix for variables, not null. 610 * @param suffixMatcher the suffix for variables, not null. 611 * @param escape the escape character. 612 * @throws IllegalArgumentException if the prefix or suffix is null. 613 */ 614 public StringSubstitutor(final StringLookup variableResolver, final StringMatcher prefixMatcher, 615 final StringMatcher suffixMatcher, final char escape) { 616 this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER); 617 } 618 619 /** 620 * Constructs a new initialized instance. 621 * 622 * @param variableResolver the variable resolver, may be null 623 * @param prefixMatcher the prefix for variables, not null 624 * @param suffixMatcher the suffix for variables, not null 625 * @param escape the escape character 626 * @param valueDelimiterMatcher the variable default value delimiter matcher, may be null 627 * @throws IllegalArgumentException if the prefix or suffix is null 628 */ 629 public StringSubstitutor(final StringLookup variableResolver, final StringMatcher prefixMatcher, 630 final StringMatcher suffixMatcher, final char escape, final StringMatcher valueDelimiterMatcher) { 631 setVariableResolver(variableResolver); 632 setVariablePrefixMatcher(prefixMatcher); 633 setVariableSuffixMatcher(suffixMatcher); 634 setEscapeChar(escape); 635 setValueDelimiterMatcher(valueDelimiterMatcher); 636 } 637 638 /** 639 * Creates a new instance based on the given. 640 * 641 * @param other The StringSubstitutor used as the source. 642 * @since 1.9 643 */ 644 public StringSubstitutor(final StringSubstitutor other) { 645 disableSubstitutionInValues = other.isDisableSubstitutionInValues(); 646 enableSubstitutionInVariables = other.isEnableSubstitutionInVariables(); 647 failOnUndefinedVariable = other.isEnableUndefinedVariableException(); 648 escapeChar = other.getEscapeChar(); 649 prefixMatcher = other.getVariablePrefixMatcher(); 650 preserveEscapes = other.isPreserveEscapes(); 651 suffixMatcher = other.getVariableSuffixMatcher(); 652 valueDelimiterMatcher = other.getValueDelimiterMatcher(); 653 variableResolver = other.getStringLookup(); 654 } 655 656 /** 657 * Checks if the specified variable is already in the stack (list) of variables. 658 * 659 * @param varName the variable name to check 660 * @param priorVariables the list of prior variables 661 */ 662 private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) { 663 if (!priorVariables.contains(varName)) { 664 return; 665 } 666 final TextStringBuilder buf = new TextStringBuilder(256); 667 buf.append("Infinite loop in property interpolation of "); 668 buf.append(priorVariables.remove(0)); 669 buf.append(": "); 670 buf.appendWithSeparators(priorVariables, "->"); 671 throw new IllegalStateException(buf.toString()); 672 } 673 674 // Escape 675 /** 676 * Returns the escape character. 677 * 678 * @return The character used for escaping variable references. 679 */ 680 public char getEscapeChar() { 681 return escapeChar; 682 } 683 684 /** 685 * Gets the StringLookup that is used to lookup variables. 686 * 687 * @return The StringLookup. 688 */ 689 public StringLookup getStringLookup() { 690 return variableResolver; 691 } 692 693 /** 694 * Gets the variable default value delimiter matcher currently in use. 695 * <p> 696 * The variable default value delimiter is the character or characters that delimit the variable name and the 697 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default 698 * value delimiter matches. 699 * </p> 700 * <p> 701 * If it returns null, then the variable default value resolution is disabled. 702 * 703 * @return The variable default value delimiter matcher in use, may be null. 704 */ 705 public StringMatcher getValueDelimiterMatcher() { 706 return valueDelimiterMatcher; 707 } 708 709 /** 710 * Gets the variable prefix matcher currently in use. 711 * <p> 712 * The variable prefix is the character or characters that identify the start of a variable. This prefix is 713 * expressed in terms of a matcher allowing advanced prefix matches. 714 * </p> 715 * 716 * @return The prefix matcher in use 717 */ 718 public StringMatcher getVariablePrefixMatcher() { 719 return prefixMatcher; 720 } 721 722 /** 723 * Gets the variable suffix matcher currently in use. 724 * <p> 725 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed 726 * in terms of a matcher allowing advanced suffix matches. 727 * </p> 728 * 729 * @return The suffix matcher in use 730 */ 731 public StringMatcher getVariableSuffixMatcher() { 732 return suffixMatcher; 733 } 734 735 /** 736 * Returns a flag whether substitution is disabled in variable values.If set to <strong>true</strong>, the values of variables 737 * can contain other variables will not be processed and substituted original variable is evaluated, e.g. 738 * 739 * <pre> 740 * Map<String, String> valuesMap = new HashMap<>(); 741 * valuesMap.put("name", "Douglas ${surname}"); 742 * valuesMap.put("surname", "Crockford"); 743 * String templateString = "Hi ${name}"; 744 * StrSubstitutor sub = new StrSubstitutor(valuesMap); 745 * String resolvedString = sub.replace(templateString); 746 * </pre> 747 * 748 * yielding: 749 * 750 * <pre> 751 * Hi Douglas ${surname} 752 * </pre> 753 * 754 * @return The substitution in variable values flag. 755 */ 756 public boolean isDisableSubstitutionInValues() { 757 return disableSubstitutionInValues; 758 } 759 760 /** 761 * Returns a flag whether substitution is done in variable names. 762 * 763 * @return The substitution in variable names flag. 764 */ 765 public boolean isEnableSubstitutionInVariables() { 766 return enableSubstitutionInVariables; 767 } 768 769 /** 770 * Returns a flag whether exception can be thrown upon undefined variable. 771 * 772 * @return The fail on undefined variable flag. 773 */ 774 public boolean isEnableUndefinedVariableException() { 775 return failOnUndefinedVariable; 776 } 777 778 /** 779 * Returns the flag controlling whether escapes are preserved during substitution. 780 * 781 * @return The preserve escape flag. 782 */ 783 public boolean isPreserveEscapes() { 784 return preserveEscapes; 785 } 786 787 /** 788 * Replaces all the occurrences of variables with their matching values from the resolver using the given source 789 * array as a template. The array is not altered by this method. 790 * 791 * @param source the character array to replace in, not altered, null returns null. 792 * @return The result of the replace operation. 793 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 794 */ 795 public String replace(final char[] source) { 796 if (source == null) { 797 return null; 798 } 799 final TextStringBuilder buf = new TextStringBuilder(source.length).append(source); 800 substitute(buf, 0, source.length); 801 return buf.toString(); 802 } 803 804 /** 805 * Replaces all the occurrences of variables with their matching values from the resolver using the given source array as a template. The array is not 806 * altered by this method. 807 * <p> 808 * Only the specified portion of the array will be processed. The rest of the array is not processed, and is not returned. 809 * </p> 810 * 811 * @param source the character array to replace in, not altered, null returns null. 812 * @param offset the start offset within the array, must be valid. 813 * @param length the length within the array to be processed, must be valid. 814 * @return The result of the replace operation. 815 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 816 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the range {@code 0 <= offset <= chars.length}. 817 * @throws StringIndexOutOfBoundsException if {@code length < 0}. 818 * @throws StringIndexOutOfBoundsException if {@code offset + length > chars.length}. 819 */ 820 public String replace(final char[] source, final int offset, final int length) { 821 if (source == null) { 822 return null; 823 } 824 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 825 substitute(buf, 0, length); 826 return buf.toString(); 827 } 828 829 /** 830 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as 831 * a template. The source is not altered by this method. 832 * 833 * @param source the buffer to use as a template, not changed, null returns null. 834 * @return The result of the replace operation. 835 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 836 */ 837 public String replace(final CharSequence source) { 838 if (source == null) { 839 return null; 840 } 841 return replace(source, 0, source.length()); 842 } 843 844 /** 845 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as 846 * a template. The source is not altered by this method. 847 * <p> 848 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not 849 * returned. 850 * </p> 851 * 852 * @param source the buffer to use as a template, not changed, null returns null. 853 * @param offset the start offset within the array, must be valid. 854 * @param length the length within the array to be processed, must be valid. 855 * @return The result of the replace operation. 856 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 857 */ 858 public String replace(final CharSequence source, final int offset, final int length) { 859 if (source == null) { 860 return null; 861 } 862 final TextStringBuilder buf = new TextStringBuilder(length).append(source.toString(), offset, length); 863 substitute(buf, 0, length); 864 return buf.toString(); 865 } 866 867 /** 868 * Replaces all the occurrences of variables in the given source object with their matching values from the 869 * resolver. The input source object is converted to a string using {@code toString} and is not altered. 870 * 871 * @param source the source to replace in, null returns null. 872 * @return The result of the replace operation. 873 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true. 874 */ 875 public String replace(final Object source) { 876 if (source == null) { 877 return null; 878 } 879 final TextStringBuilder buf = new TextStringBuilder().append(source); 880 substitute(buf, 0, buf.length()); 881 return buf.toString(); 882 } 883 884 /** 885 * Replaces all the occurrences of variables with their matching values from the resolver using the given source 886 * string as a template. 887 * 888 * @param source the string to replace in, null returns null. 889 * @return The result of the replace operation. 890 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 891 */ 892 public String replace(final String source) { 893 if (source == null) { 894 return null; 895 } 896 final TextStringBuilder buf = new TextStringBuilder(source); 897 if (!substitute(buf, 0, source.length())) { 898 return source; 899 } 900 return buf.toString(); 901 } 902 903 /** 904 * Replaces all the occurrences of variables with their matching values from the resolver using the given source string as a template. 905 * <p> 906 * Only the specified portion of the string will be processed. The rest of the string is not processed, and is not returned. 907 * </p> 908 * 909 * @param source the string to replace in, null returns null. 910 * @param offset the start offset within the source, must be valid. 911 * @param length the length within the source to be processed, must be valid. 912 * @return The result of the replace operation. 913 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 914 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the range {@code 0 <= offset <= source.length()}. 915 * @throws StringIndexOutOfBoundsException if {@code length < 0}. 916 * @throws StringIndexOutOfBoundsException if {@code offset + length > source.length()}. 917 */ 918 public String replace(final String source, final int offset, final int length) { 919 if (source == null) { 920 return null; 921 } 922 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 923 if (!substitute(buf, 0, length)) { 924 return source.substring(offset, offset + length); 925 } 926 return buf.toString(); 927 } 928 929 /** 930 * Replaces all the occurrences of variables with their matching values from the resolver using the given source 931 * buffer as a template. The buffer is not altered by this method. 932 * 933 * @param source the buffer to use as a template, not changed, null returns null. 934 * @return The result of the replace operation. 935 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 936 */ 937 public String replace(final StringBuffer source) { 938 if (source == null) { 939 return null; 940 } 941 final TextStringBuilder buf = new TextStringBuilder(source.length()).append(source); 942 substitute(buf, 0, buf.length()); 943 return buf.toString(); 944 } 945 946 /** 947 * Replaces all the occurrences of variables with their matching values from the resolver using the given source 948 * buffer as a template. The buffer is not altered by this method. 949 * <p> 950 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not 951 * returned. 952 * </p> 953 * 954 * @param source the buffer to use as a template, not changed, null returns null. 955 * @param offset the start offset within the source, must be valid. 956 * @param length the length within the source to be processed, must be valid. 957 * @return The result of the replace operation. 958 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 959 */ 960 public String replace(final StringBuffer source, final int offset, final int length) { 961 if (source == null) { 962 return null; 963 } 964 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 965 substitute(buf, 0, length); 966 return buf.toString(); 967 } 968 969 /** 970 * Replaces all the occurrences of variables with their matching values from the resolver using the given source 971 * builder as a template. The builder is not altered by this method. 972 * 973 * @param source the builder to use as a template, not changed, null returns null. 974 * @return The result of the replace operation. 975 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 976 */ 977 public String replace(final TextStringBuilder source) { 978 if (source == null) { 979 return null; 980 } 981 final TextStringBuilder builder = new TextStringBuilder(source.length()).append(source); 982 substitute(builder, 0, builder.length()); 983 return builder.toString(); 984 } 985 986 /** 987 * Replaces all the occurrences of variables with their matching values from the resolver using the given source 988 * builder as a template. The builder is not altered by this method. 989 * <p> 990 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, and is not 991 * returned. 992 * </p> 993 * 994 * @param source the builder to use as a template, not changed, null returns null. 995 * @param offset the start offset within the source, must be valid. 996 * @param length the length within the source to be processed, must be valid. 997 * @return The result of the replace operation. 998 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 999 */ 1000 public String replace(final TextStringBuilder source, final int offset, final int length) { 1001 if (source == null) { 1002 return null; 1003 } 1004 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 1005 substitute(buf, 0, length); 1006 return buf.toString(); 1007 } 1008 1009 /** 1010 * Replaces all the occurrences of variables within the given source buffer with their matching values from the 1011 * resolver. The buffer is updated with the result. 1012 * 1013 * @param source the buffer to replace in, updated, null returns zero. 1014 * @return true if altered 1015 */ 1016 public boolean replaceIn(final StringBuffer source) { 1017 if (source == null) { 1018 return false; 1019 } 1020 return replaceIn(source, 0, source.length()); 1021 } 1022 1023 /** 1024 * Replaces all the occurrences of variables within the given source buffer with their matching values from the 1025 * resolver. The buffer is updated with the result. 1026 * <p> 1027 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is 1028 * not deleted. 1029 * </p> 1030 * 1031 * @param source the buffer to replace in, updated, null returns zero. 1032 * @param offset the start offset within the source, must be valid. 1033 * @param length the length within the source to be processed, must be valid. 1034 * @return true if altered. 1035 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 1036 */ 1037 public boolean replaceIn(final StringBuffer source, final int offset, final int length) { 1038 if (source == null) { 1039 return false; 1040 } 1041 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 1042 if (!substitute(buf, 0, length)) { 1043 return false; 1044 } 1045 source.replace(offset, offset + length, buf.toString()); 1046 return true; 1047 } 1048 1049 /** 1050 * Replaces all the occurrences of variables within the given source buffer with their matching values from the 1051 * resolver. The buffer is updated with the result. 1052 * 1053 * @param source the buffer to replace in, updated, null returns zero. 1054 * @return true if altered. 1055 */ 1056 public boolean replaceIn(final StringBuilder source) { 1057 if (source == null) { 1058 return false; 1059 } 1060 return replaceIn(source, 0, source.length()); 1061 } 1062 1063 /** 1064 * Replaces all the occurrences of variables within the given source builder with their matching values from the 1065 * resolver. The builder is updated with the result. 1066 * <p> 1067 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is 1068 * not deleted. 1069 * </p> 1070 * 1071 * @param source the buffer to replace in, updated, null returns zero. 1072 * @param offset the start offset within the source, must be valid. 1073 * @param length the length within the source to be processed, must be valid. 1074 * @return true if altered. 1075 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 1076 */ 1077 public boolean replaceIn(final StringBuilder source, final int offset, final int length) { 1078 if (source == null) { 1079 return false; 1080 } 1081 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 1082 if (!substitute(buf, 0, length)) { 1083 return false; 1084 } 1085 source.replace(offset, offset + length, buf.toString()); 1086 return true; 1087 } 1088 1089 /** 1090 * Replaces all the occurrences of variables within the given source builder with their matching values from the 1091 * resolver. 1092 * 1093 * @param source the builder to replace in, updated, null returns zero. 1094 * @return true if altered. 1095 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 1096 */ 1097 public boolean replaceIn(final TextStringBuilder source) { 1098 if (source == null) { 1099 return false; 1100 } 1101 return substitute(source, 0, source.length()); 1102 } 1103 1104 /** 1105 * Replaces all the occurrences of variables within the given source builder with their matching values from the 1106 * resolver. 1107 * <p> 1108 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, but it is 1109 * not deleted. 1110 * </p> 1111 * 1112 * @param source the builder to replace in, null returns zero. 1113 * @param offset the start offset within the source, must be valid. 1114 * @param length the length within the source to be processed, must be valid. 1115 * @return true if altered. 1116 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 1117 */ 1118 public boolean replaceIn(final TextStringBuilder source, final int offset, final int length) { 1119 if (source == null) { 1120 return false; 1121 } 1122 return substitute(source, offset, length); 1123 } 1124 1125 /** 1126 * Internal method that resolves the value of a variable. 1127 * <p> 1128 * Most users of this class do not need to call this method. This method is called automatically by the substitution 1129 * process. 1130 * </p> 1131 * <p> 1132 * Writers of subclasses can override this method if they need to alter how each substitution occurs. The method is 1133 * passed the variable's name and must return the corresponding value. This implementation uses the 1134 * {@link #getStringLookup()} with the variable's name as the key. 1135 * </p> 1136 * 1137 * @param variableName the name of the variable, not null. 1138 * @param buf the buffer where the substitution is occurring, not null. 1139 * @param startPos the start position of the variable including the prefix, valid. 1140 * @param endPos the end position of the variable including the suffix, valid. 1141 * @return The variable's value or <strong>null</strong> if the variable is unknown. 1142 */ 1143 protected String resolveVariable(final String variableName, final TextStringBuilder buf, final int startPos, 1144 final int endPos) { 1145 final StringLookup resolver = getStringLookup(); 1146 if (resolver == null) { 1147 return null; 1148 } 1149 return resolver.apply(variableName); 1150 } 1151 1152 /** 1153 * Sets a flag whether substitution is done in variable values (recursive). 1154 * 1155 * @param disableSubstitutionInValues true if substitution in variable value are disabled. 1156 * @return {@code this} instance. 1157 */ 1158 public StringSubstitutor setDisableSubstitutionInValues(final boolean disableSubstitutionInValues) { 1159 this.disableSubstitutionInValues = disableSubstitutionInValues; 1160 return this; 1161 } 1162 1163 /** 1164 * Sets a flag whether substitution is done in variable names. If set to <strong>true</strong>, the names of variables can 1165 * contain other variables which are processed first before the original variable is evaluated, e.g. 1166 * {@code ${jre-${java.version}}}. The default value is <strong>false</strong>. 1167 * 1168 * @param enableSubstitutionInVariables the new value of the flag. 1169 * @return {@code this} instance. 1170 */ 1171 public StringSubstitutor setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) { 1172 this.enableSubstitutionInVariables = enableSubstitutionInVariables; 1173 return this; 1174 } 1175 1176 /** 1177 * Sets a flag whether exception should be thrown if any variable is undefined. 1178 * 1179 * @param failOnUndefinedVariable true if exception should be thrown on undefined variable. 1180 * @return {@code this} instance. 1181 */ 1182 public StringSubstitutor setEnableUndefinedVariableException(final boolean failOnUndefinedVariable) { 1183 this.failOnUndefinedVariable = failOnUndefinedVariable; 1184 return this; 1185 } 1186 1187 /** 1188 * Sets the escape character. If this character is placed before a variable reference in the source text, this 1189 * variable will be ignored. 1190 * 1191 * @param escapeChar the escape character (0 for disabling escaping). 1192 * @return {@code this} instance. 1193 */ 1194 public StringSubstitutor setEscapeChar(final char escapeChar) { 1195 this.escapeChar = escapeChar; 1196 return this; 1197 } 1198 1199 /** 1200 * Sets a flag controlling whether escapes are preserved during substitution. If set to <strong>true</strong>, the escape 1201 * character is retained during substitution (e.g. {@code $${this-is-escaped}} remains {@code $${this-is-escaped}}). 1202 * If set to <strong>false</strong>, the escape character is removed during substitution (e.g. {@code $${this-is-escaped}} 1203 * becomes {@code ${this-is-escaped}}). The default value is <strong>false</strong> 1204 * 1205 * @param preserveEscapes true if escapes are to be preserved. 1206 * @return {@code this} instance. 1207 */ 1208 public StringSubstitutor setPreserveEscapes(final boolean preserveEscapes) { 1209 this.preserveEscapes = preserveEscapes; 1210 return this; 1211 } 1212 1213 /** 1214 * Sets the variable default value delimiter to use. 1215 * <p> 1216 * The variable default value delimiter is the character or characters that delimit the variable name and the 1217 * variable default value. This method allows a single character variable default value delimiter to be easily set. 1218 * </p> 1219 * 1220 * @param valueDelimiter the variable default value delimiter character to use. 1221 * @return {@code this} instance. 1222 */ 1223 public StringSubstitutor setValueDelimiter(final char valueDelimiter) { 1224 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.charMatcher(valueDelimiter)); 1225 } 1226 1227 /** 1228 * Sets the variable default value delimiter to use. 1229 * <p> 1230 * The variable default value delimiter is the character or characters that delimit the variable name and the 1231 * variable default value. This method allows a string variable default value delimiter to be easily set. 1232 * </p> 1233 * <p> 1234 * If the {@code valueDelimiter} is null or empty string, then the variable default value resolution becomes 1235 * disabled. 1236 * </p> 1237 * 1238 * @param valueDelimiter the variable default value delimiter string to use, may be null or empty. 1239 * @return {@code this} instance. 1240 */ 1241 public StringSubstitutor setValueDelimiter(final String valueDelimiter) { 1242 if (valueDelimiter == null || valueDelimiter.isEmpty()) { 1243 setValueDelimiterMatcher(null); 1244 return this; 1245 } 1246 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.stringMatcher(valueDelimiter)); 1247 } 1248 1249 /** 1250 * Sets the variable default value delimiter matcher to use. 1251 * <p> 1252 * The variable default value delimiter is the character or characters that delimit the variable name and the 1253 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default 1254 * value delimiter matches. 1255 * </p> 1256 * <p> 1257 * If the {@code valueDelimiterMatcher} is null, then the variable default value resolution becomes disabled. 1258 * </p> 1259 * 1260 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null. 1261 * @return {@code this} instance. 1262 */ 1263 public StringSubstitutor setValueDelimiterMatcher(final StringMatcher valueDelimiterMatcher) { 1264 this.valueDelimiterMatcher = valueDelimiterMatcher; 1265 return this; 1266 } 1267 1268 /** 1269 * Sets the variable prefix to use. 1270 * <p> 1271 * The variable prefix is the character or characters that identify the start of a variable. This method allows a 1272 * single character prefix to be easily set. 1273 * </p> 1274 * 1275 * @param prefix the prefix character to use. 1276 * @return {@code this} instance. 1277 */ 1278 public StringSubstitutor setVariablePrefix(final char prefix) { 1279 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.charMatcher(prefix)); 1280 } 1281 1282 /** 1283 * Sets the variable prefix to use. 1284 * <p> 1285 * The variable prefix is the character or characters that identify the start of a variable. This method allows a 1286 * string prefix to be easily set. 1287 * </p> 1288 * 1289 * @param prefix the prefix for variables, not null. 1290 * @return {@code this} instance. 1291 * @throws IllegalArgumentException if the prefix is null. 1292 */ 1293 public StringSubstitutor setVariablePrefix(final String prefix) { 1294 Validate.isTrue(prefix != null, "Variable prefix must not be null!"); 1295 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(prefix)); 1296 } 1297 1298 /** 1299 * Sets the variable prefix matcher currently in use. 1300 * <p> 1301 * The variable prefix is the character or characters that identify the start of a variable. This prefix is 1302 * expressed in terms of a matcher allowing advanced prefix matches. 1303 * </p> 1304 * 1305 * @param prefixMatcher the prefix matcher to use, null ignored. 1306 * @return {@code this} instance. 1307 * @throws IllegalArgumentException if the prefix matcher is null. 1308 */ 1309 public StringSubstitutor setVariablePrefixMatcher(final StringMatcher prefixMatcher) { 1310 Validate.isTrue(prefixMatcher != null, "Variable prefix matcher must not be null!"); 1311 this.prefixMatcher = prefixMatcher; 1312 return this; 1313 } 1314 1315 /** 1316 * Sets the VariableResolver that is used to lookup variables. 1317 * 1318 * @param variableResolver the VariableResolver. 1319 * @return {@code this} instance. 1320 */ 1321 public StringSubstitutor setVariableResolver(final StringLookup variableResolver) { 1322 this.variableResolver = variableResolver; 1323 return this; 1324 } 1325 1326 /** 1327 * Sets the variable suffix to use. 1328 * <p> 1329 * The variable suffix is the character or characters that identify the end of a variable. This method allows a 1330 * single character suffix to be easily set. 1331 * </p> 1332 * 1333 * @param suffix the suffix character to use. 1334 * @return {@code this} instance. 1335 */ 1336 public StringSubstitutor setVariableSuffix(final char suffix) { 1337 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.charMatcher(suffix)); 1338 } 1339 1340 /** 1341 * Sets the variable suffix to use. 1342 * <p> 1343 * The variable suffix is the character or characters that identify the end of a variable. This method allows a 1344 * string suffix to be easily set. 1345 * </p> 1346 * 1347 * @param suffix the suffix for variables, not null. 1348 * @return {@code this} instance. 1349 * @throws IllegalArgumentException if the suffix is null. 1350 */ 1351 public StringSubstitutor setVariableSuffix(final String suffix) { 1352 Validate.isTrue(suffix != null, "Variable suffix must not be null!"); 1353 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(suffix)); 1354 } 1355 1356 /** 1357 * Sets the variable suffix matcher currently in use. 1358 * <p> 1359 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed 1360 * in terms of a matcher allowing advanced suffix matches. 1361 * </p> 1362 * 1363 * @param suffixMatcher the suffix matcher to use, null ignored. 1364 * @return {@code this} instance. 1365 * @throws IllegalArgumentException if the suffix matcher is null. 1366 */ 1367 public StringSubstitutor setVariableSuffixMatcher(final StringMatcher suffixMatcher) { 1368 Validate.isTrue(suffixMatcher != null, "Variable suffix matcher must not be null!"); 1369 this.suffixMatcher = suffixMatcher; 1370 return this; 1371 } 1372 1373 /** 1374 * Internal method that substitutes the variables. 1375 * <p> 1376 * Most users of this class do not need to call this method. This method will be called automatically by another 1377 * (public) method. 1378 * </p> 1379 * <p> 1380 * Writers of subclasses can override this method if they need access to the substitution process at the start or 1381 * end. 1382 * </p> 1383 * 1384 * @param builder the string builder to substitute into, not null. 1385 * @param offset the start offset within the builder, must be valid. 1386 * @param length the length within the builder to be processed, must be valid. 1387 * @return true if altered. 1388 */ 1389 protected boolean substitute(final TextStringBuilder builder, final int offset, final int length) { 1390 return substitute(builder, offset, length, null).altered; 1391 } 1392 1393 /** 1394 * Recursive handler for multiple levels of interpolation. This is the main interpolation method, which resolves the 1395 * values of all variable references contained in the passed in text. 1396 * 1397 * @param builder the string builder to substitute into, not null. 1398 * @param offset the start offset within the builder, must be valid. 1399 * @param length the length within the builder to be processed, must be valid. 1400 * @param priorVariables the stack keeping track of the replaced variables, may be null. 1401 * @return The result. 1402 * @throws IllegalArgumentException if variable is not found and <code>isEnableUndefinedVariableException() == true</code>. 1403 * @since 1.9 1404 */ 1405 private Result substitute(final TextStringBuilder builder, final int offset, final int length, 1406 List<String> priorVariables) { 1407 Objects.requireNonNull(builder, "builder"); 1408 final StringMatcher prefixMatcher = getVariablePrefixMatcher(); 1409 final StringMatcher suffixMatcher = getVariableSuffixMatcher(); 1410 final char escapeCh = getEscapeChar(); 1411 final StringMatcher valueDelimMatcher = getValueDelimiterMatcher(); 1412 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables(); 1413 final boolean substitutionInValuesDisabled = isDisableSubstitutionInValues(); 1414 final boolean undefinedVariableException = isEnableUndefinedVariableException(); 1415 final boolean preserveEscapes = isPreserveEscapes(); 1416 1417 boolean altered = false; 1418 int lengthChange = 0; 1419 int bufEnd = offset + length; 1420 int pos = offset; 1421 int escPos = -1; 1422 outer: while (pos < bufEnd) { 1423 final int startMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd); 1424 if (startMatchLen == 0) { 1425 pos++; 1426 } else { 1427 // found variable start marker 1428 if (pos > offset && builder.charAt(pos - 1) == escapeCh) { 1429 // escape detected 1430 if (preserveEscapes) { 1431 // keep escape 1432 pos++; 1433 continue; 1434 } 1435 // mark esc ch for deletion if we find a complete variable 1436 escPos = pos - 1; 1437 } 1438 // find suffix 1439 int startPos = pos; 1440 pos += startMatchLen; 1441 int endMatchLen = 0; 1442 int nestedVarCount = 0; 1443 while (pos < bufEnd) { 1444 if (substitutionInVariablesEnabled && prefixMatcher.isMatch(builder, pos, offset, bufEnd) != 0) { 1445 // found a nested variable start 1446 endMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd); 1447 nestedVarCount++; 1448 pos += endMatchLen; 1449 continue; 1450 } 1451 1452 endMatchLen = suffixMatcher.isMatch(builder, pos, offset, bufEnd); 1453 if (endMatchLen == 0) { 1454 pos++; 1455 } else { 1456 // found variable end marker 1457 if (nestedVarCount == 0) { 1458 if (escPos >= 0) { 1459 // delete escape 1460 builder.deleteCharAt(escPos); 1461 escPos = -1; 1462 lengthChange--; 1463 altered = true; 1464 bufEnd--; 1465 pos = startPos + 1; 1466 startPos--; 1467 continue outer; 1468 } 1469 // get var name 1470 String varNameExpr = builder.midString(startPos + startMatchLen, 1471 pos - startPos - startMatchLen); 1472 if (substitutionInVariablesEnabled) { 1473 final TextStringBuilder bufName = new TextStringBuilder(varNameExpr); 1474 substitute(bufName, 0, bufName.length()); 1475 varNameExpr = bufName.toString(); 1476 } 1477 pos += endMatchLen; 1478 final int endPos = pos; 1479 1480 String varName = varNameExpr; 1481 String varDefaultValue = null; 1482 1483 if (valueDelimMatcher != null) { 1484 final char[] varNameExprChars = varNameExpr.toCharArray(); 1485 int valueDelimiterMatchLen = 0; 1486 for (int i = 0; i < varNameExprChars.length; i++) { 1487 // if there's any nested variable when nested variable substitution disabled, 1488 // then stop resolving name and default value. 1489 if (!substitutionInVariablesEnabled && prefixMatcher.isMatch(varNameExprChars, i, i, 1490 varNameExprChars.length) != 0) { 1491 break; 1492 } 1493 if (valueDelimMatcher.isMatch(varNameExprChars, i, 0, 1494 varNameExprChars.length) != 0) { 1495 valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i, 0, 1496 varNameExprChars.length); 1497 varName = varNameExpr.substring(0, i); 1498 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen); 1499 break; 1500 } 1501 } 1502 } 1503 1504 // on the first call initialize priorVariables 1505 if (priorVariables == null) { 1506 priorVariables = new ArrayList<>(); 1507 priorVariables.add(builder.midString(offset, length)); 1508 } 1509 1510 // handle cyclic substitution 1511 checkCyclicSubstitution(varName, priorVariables); 1512 priorVariables.add(varName); 1513 1514 // resolve the variable 1515 String varValue = resolveVariable(varName, builder, startPos, endPos); 1516 if (varValue == null) { 1517 varValue = varDefaultValue; 1518 } 1519 if (varValue != null) { 1520 final int varLen = varValue.length(); 1521 builder.replace(startPos, endPos, varValue); 1522 altered = true; 1523 int change = 0; 1524 if (!substitutionInValuesDisabled) { // recursive replace 1525 change = substitute(builder, startPos, varLen, priorVariables).lengthChange; 1526 } 1527 change = change + varLen - (endPos - startPos); 1528 pos += change; 1529 bufEnd += change; 1530 lengthChange += change; 1531 } else if (undefinedVariableException) { 1532 throw new IllegalArgumentException( 1533 String.format("Cannot resolve variable '%s' (enableSubstitutionInVariables=%s).", 1534 varName, substitutionInVariablesEnabled)); 1535 } 1536 1537 // remove variable from the cyclic stack 1538 priorVariables.remove(priorVariables.size() - 1); 1539 break; 1540 } 1541 nestedVarCount--; 1542 pos += endMatchLen; 1543 } 1544 } 1545 } 1546 } 1547 return new Result(altered, lengthChange); 1548 } 1549 1550 /** 1551 * Returns a string representation of the object. 1552 * 1553 * @return a string representation of the object. 1554 * @since 1.11.0 1555 */ 1556 @Override 1557 public String toString() { 1558 // @formatter:off 1559 return new StringBuilder() 1560 .append("StringSubstitutor [disableSubstitutionInValues=") 1561 .append(disableSubstitutionInValues) 1562 .append(", enableSubstitutionInVariables=") 1563 .append(enableSubstitutionInVariables) 1564 .append(", enableUndefinedVariableException=") 1565 .append(failOnUndefinedVariable) 1566 .append(", escapeChar=") 1567 .append(escapeChar) 1568 .append(", prefixMatcher=") 1569 .append(prefixMatcher) 1570 .append(", preserveEscapes=") 1571 .append(preserveEscapes) 1572 .append(", suffixMatcher=") 1573 .append(suffixMatcher) 1574 .append(", valueDelimiterMatcher=") 1575 .append(valueDelimiterMatcher) 1576 .append(", variableResolver=") 1577 .append(variableResolver) 1578 .append("]") 1579 .toString(); 1580 // @formatter:on 1581 } 1582}