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 /** 675 * Returns the escape character. 676 * 677 * @return The character used for escaping variable references. 678 */ 679 public char getEscapeChar() { 680 return escapeChar; 681 } 682 683 /** 684 * Gets the StringLookup that is used to lookup variables. 685 * 686 * @return The StringLookup. 687 */ 688 public StringLookup getStringLookup() { 689 return variableResolver; 690 } 691 692 /** 693 * Gets the variable default value delimiter matcher currently in use. 694 * <p> 695 * The variable default value delimiter is the character or characters that delimit the variable name and the 696 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default 697 * value delimiter matches. 698 * </p> 699 * <p> 700 * If it returns null, then the variable default value resolution is disabled. 701 * 702 * @return The variable default value delimiter matcher in use, may be null. 703 */ 704 public StringMatcher getValueDelimiterMatcher() { 705 return valueDelimiterMatcher; 706 } 707 708 /** 709 * Gets the variable prefix matcher currently in use. 710 * <p> 711 * The variable prefix is the character or characters that identify the start of a variable. This prefix is 712 * expressed in terms of a matcher allowing advanced prefix matches. 713 * </p> 714 * 715 * @return The prefix matcher in use 716 */ 717 public StringMatcher getVariablePrefixMatcher() { 718 return prefixMatcher; 719 } 720 721 /** 722 * Gets the variable suffix matcher currently in use. 723 * <p> 724 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed 725 * in terms of a matcher allowing advanced suffix matches. 726 * </p> 727 * 728 * @return The suffix matcher in use 729 */ 730 public StringMatcher getVariableSuffixMatcher() { 731 return suffixMatcher; 732 } 733 734 /** 735 * Checks whether the specified buffer contains a variable suffix after the given position. 736 * 737 * @param builder The string builder to check, not null. 738 * @param pos The position to start checking from. 739 * @param offset The start offset within the builder, must be valid. 740 * @param bufEnd The end offset within the builder, must be valid. 741 * @param suffixMatcher The suffix matcher to use, not null. 742 * @return true if a suffix is found after the given position. 743 */ 744 private boolean hasLaterSuffix(final TextStringBuilder builder, int pos, final int offset, final int bufEnd, final StringMatcher suffixMatcher) { 745 while (pos < bufEnd) { 746 if (suffixMatcher.isMatch(builder, pos, offset, bufEnd) != 0) { 747 return true; 748 } 749 pos++; 750 } 751 return false; 752 } 753 754 /** 755 * Returns a flag whether substitution is disabled in variable values.If set to <strong>true</strong>, the values of variables 756 * can contain other variables will not be processed and substituted original variable is evaluated, e.g. 757 * 758 * <pre> 759 * Map<String, String> valuesMap = new HashMap<>(); 760 * valuesMap.put("name", "Douglas ${surname}"); 761 * valuesMap.put("surname", "Crockford"); 762 * String templateString = "Hi ${name}"; 763 * StrSubstitutor sub = new StrSubstitutor(valuesMap); 764 * String resolvedString = sub.replace(templateString); 765 * </pre> 766 * 767 * yielding: 768 * 769 * <pre> 770 * Hi Douglas ${surname} 771 * </pre> 772 * 773 * @return The substitution in variable values flag. 774 */ 775 public boolean isDisableSubstitutionInValues() { 776 return disableSubstitutionInValues; 777 } 778 779 /** 780 * Returns a flag whether substitution is done in variable names. 781 * 782 * @return The substitution in variable names flag. 783 */ 784 public boolean isEnableSubstitutionInVariables() { 785 return enableSubstitutionInVariables; 786 } 787 788 /** 789 * Returns a flag whether exception can be thrown upon undefined variable. 790 * 791 * @return The fail on undefined variable flag. 792 */ 793 public boolean isEnableUndefinedVariableException() { 794 return failOnUndefinedVariable; 795 } 796 797 /** 798 * Returns the flag controlling whether escapes are preserved during substitution. 799 * 800 * @return The preserve escape flag. 801 */ 802 public boolean isPreserveEscapes() { 803 return preserveEscapes; 804 } 805 806 /** 807 * Replaces all the occurrences of variables with their matching values from the resolver using the given source 808 * array as a template. The array is not altered by this method. 809 * 810 * @param source The character array to replace in, not altered, null returns null. 811 * @return The result of the replace operation. 812 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 813 */ 814 public String replace(final char[] source) { 815 if (source == null) { 816 return null; 817 } 818 final TextStringBuilder buf = new TextStringBuilder(source.length).append(source); 819 substitute(buf, 0, source.length); 820 return buf.toString(); 821 } 822 823 /** 824 * 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 825 * altered by this method. 826 * <p> 827 * Only the specified portion of the array will be processed. The rest of the array is not processed, and is not returned. 828 * </p> 829 * 830 * @param source The character array to replace in, not altered, null returns null. 831 * @param offset The start offset within the array, must be valid. 832 * @param length The length within the array to be processed, must be valid. 833 * @return The result of the replace operation. 834 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 835 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the range {@code 0 <= offset <= chars.length}. 836 * @throws StringIndexOutOfBoundsException if {@code length < 0}. 837 * @throws StringIndexOutOfBoundsException if {@code offset + length > chars.length}. 838 */ 839 public String replace(final char[] source, final int offset, final int length) { 840 if (source == null) { 841 return null; 842 } 843 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 844 substitute(buf, 0, length); 845 return buf.toString(); 846 } 847 848 /** 849 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as 850 * a template. The source is not altered by this method. 851 * 852 * @param source The buffer to use as a template, not changed, null returns null. 853 * @return The result of the replace operation. 854 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 855 */ 856 public String replace(final CharSequence source) { 857 if (source == null) { 858 return null; 859 } 860 return replace(source, 0, source.length()); 861 } 862 863 /** 864 * Replaces all the occurrences of variables with their matching values from the resolver using the given source as 865 * a template. The source is not altered by this method. 866 * <p> 867 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not 868 * returned. 869 * </p> 870 * 871 * @param source The buffer to use as a template, not changed, null returns null. 872 * @param offset The start offset within the array, must be valid. 873 * @param length The length within the array to be processed, must be valid. 874 * @return The result of the replace operation. 875 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 876 */ 877 public String replace(final CharSequence source, final int offset, final int length) { 878 if (source == null) { 879 return null; 880 } 881 final TextStringBuilder buf = new TextStringBuilder(length).append(source.toString(), offset, length); 882 substitute(buf, 0, length); 883 return buf.toString(); 884 } 885 886 /** 887 * Replaces all the occurrences of variables in the given source object with their matching values from the 888 * resolver. The input source object is converted to a string using {@code toString} and is not altered. 889 * 890 * @param source The source to replace in, null returns null. 891 * @return The result of the replace operation. 892 * @throws IllegalArgumentException if a variable is not found and enableUndefinedVariableException is true. 893 */ 894 public String replace(final Object source) { 895 if (source == null) { 896 return null; 897 } 898 final TextStringBuilder buf = new TextStringBuilder().append(source); 899 substitute(buf, 0, buf.length()); 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 905 * string as a template. 906 * 907 * @param source The string to replace in, null returns null. 908 * @return The result of the replace operation. 909 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 910 */ 911 public String replace(final String source) { 912 if (source == null) { 913 return null; 914 } 915 final TextStringBuilder buf = new TextStringBuilder(source); 916 if (!substitute(buf, 0, source.length())) { 917 return source; 918 } 919 return buf.toString(); 920 } 921 922 /** 923 * Replaces all the occurrences of variables with their matching values from the resolver using the given source string as a template. 924 * <p> 925 * Only the specified portion of the string will be processed. The rest of the string is not processed, and is not returned. 926 * </p> 927 * 928 * @param source The string to replace in, null returns null. 929 * @param offset The start offset within the source, must be valid. 930 * @param length The length within the source to be processed, must be valid. 931 * @return The result of the replace operation. 932 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 933 * @throws StringIndexOutOfBoundsException if {@code offset} is not in the range {@code 0 <= offset <= source.length()}. 934 * @throws StringIndexOutOfBoundsException if {@code length < 0}. 935 * @throws StringIndexOutOfBoundsException if {@code offset + length > source.length()}. 936 */ 937 public String replace(final String source, final int offset, final int length) { 938 if (source == null) { 939 return null; 940 } 941 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 942 if (!substitute(buf, 0, length)) { 943 return source.substring(offset, offset + length); 944 } 945 return buf.toString(); 946 } 947 948 /** 949 * Replaces all the occurrences of variables with their matching values from the resolver using the given source 950 * buffer as a template. The buffer is not altered by this method. 951 * 952 * @param source The buffer to use as a template, not changed, null returns null. 953 * @return The result of the replace operation. 954 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 955 */ 956 public String replace(final StringBuffer source) { 957 if (source == null) { 958 return null; 959 } 960 final TextStringBuilder buf = new TextStringBuilder(source.length()).append(source); 961 substitute(buf, 0, buf.length()); 962 return buf.toString(); 963 } 964 965 /** 966 * Replaces all the occurrences of variables with their matching values from the resolver using the given source 967 * buffer as a template. The buffer is not altered by this method. 968 * <p> 969 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not 970 * returned. 971 * </p> 972 * 973 * @param source The buffer to use as a template, not changed, null returns null. 974 * @param offset The start offset within the source, must be valid. 975 * @param length The length within the source to be processed, must be valid. 976 * @return The result of the replace operation. 977 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 978 */ 979 public String replace(final StringBuffer source, final int offset, final int length) { 980 if (source == null) { 981 return null; 982 } 983 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 984 substitute(buf, 0, length); 985 return buf.toString(); 986 } 987 988 /** 989 * Replaces all the occurrences of variables with their matching values from the resolver using the given source 990 * builder as a template. The builder is not altered by this method. 991 * 992 * @param source The builder to use as a template, not changed, null returns null. 993 * @return The result of the replace operation. 994 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 995 */ 996 public String replace(final TextStringBuilder source) { 997 if (source == null) { 998 return null; 999 } 1000 final TextStringBuilder builder = new TextStringBuilder(source.length()).append(source); 1001 substitute(builder, 0, builder.length()); 1002 return builder.toString(); 1003 } 1004 1005 /** 1006 * Replaces all the occurrences of variables with their matching values from the resolver using the given source 1007 * builder as a template. The builder is not altered by this method. 1008 * <p> 1009 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, and is not 1010 * returned. 1011 * </p> 1012 * 1013 * @param source The builder to use as a template, not changed, null returns null. 1014 * @param offset The start offset within the source, must be valid. 1015 * @param length The length within the source to be processed, must be valid. 1016 * @return The result of the replace operation. 1017 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 1018 */ 1019 public String replace(final TextStringBuilder source, final int offset, final int length) { 1020 if (source == null) { 1021 return null; 1022 } 1023 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 1024 substitute(buf, 0, length); 1025 return buf.toString(); 1026 } 1027 1028 /** 1029 * Replaces all the occurrences of variables within the given source buffer with their matching values from the 1030 * resolver. The buffer is updated with the result. 1031 * 1032 * @param source The buffer to replace in, updated, null returns zero. 1033 * @return true if altered 1034 */ 1035 public boolean replaceIn(final StringBuffer source) { 1036 if (source == null) { 1037 return false; 1038 } 1039 return replaceIn(source, 0, source.length()); 1040 } 1041 1042 /** 1043 * Replaces all the occurrences of variables within the given source buffer with their matching values from the 1044 * resolver. The buffer is updated with the result. 1045 * <p> 1046 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is 1047 * not deleted. 1048 * </p> 1049 * 1050 * @param source The buffer to replace in, updated, null returns zero. 1051 * @param offset The start offset within the source, must be valid. 1052 * @param length The length within the source to be processed, must be valid. 1053 * @return true if altered. 1054 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 1055 */ 1056 public boolean replaceIn(final StringBuffer source, final int offset, final int length) { 1057 if (source == null) { 1058 return false; 1059 } 1060 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 1061 if (!substitute(buf, 0, length)) { 1062 return false; 1063 } 1064 source.replace(offset, offset + length, buf.toString()); 1065 return true; 1066 } 1067 1068 /** 1069 * Replaces all the occurrences of variables within the given source buffer with their matching values from the 1070 * resolver. The buffer is updated with the result. 1071 * 1072 * @param source The buffer to replace in, updated, null returns zero. 1073 * @return true if altered. 1074 */ 1075 public boolean replaceIn(final StringBuilder source) { 1076 if (source == null) { 1077 return false; 1078 } 1079 return replaceIn(source, 0, source.length()); 1080 } 1081 1082 /** 1083 * Replaces all the occurrences of variables within the given source builder with their matching values from the 1084 * resolver. The builder is updated with the result. 1085 * <p> 1086 * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is 1087 * not deleted. 1088 * </p> 1089 * 1090 * @param source The buffer to replace in, updated, null returns zero. 1091 * @param offset The start offset within the source, must be valid. 1092 * @param length The length within the source to be processed, must be valid. 1093 * @return true if altered. 1094 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 1095 */ 1096 public boolean replaceIn(final StringBuilder source, final int offset, final int length) { 1097 if (source == null) { 1098 return false; 1099 } 1100 final TextStringBuilder buf = new TextStringBuilder(length).append(source, offset, length); 1101 if (!substitute(buf, 0, length)) { 1102 return false; 1103 } 1104 source.replace(offset, offset + length, buf.toString()); 1105 return true; 1106 } 1107 1108 /** 1109 * Replaces all the occurrences of variables within the given source builder with their matching values from the 1110 * resolver. 1111 * 1112 * @param source The builder to replace in, updated, null returns zero. 1113 * @return true if altered. 1114 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 1115 */ 1116 public boolean replaceIn(final TextStringBuilder source) { 1117 if (source == null) { 1118 return false; 1119 } 1120 return substitute(source, 0, source.length()); 1121 } 1122 1123 /** 1124 * Replaces all the occurrences of variables within the given source builder with their matching values from the 1125 * resolver. 1126 * <p> 1127 * Only the specified portion of the builder will be processed. The rest of the builder is not processed, but it is 1128 * not deleted. 1129 * </p> 1130 * 1131 * @param source The builder to replace in, null returns zero. 1132 * @param offset The start offset within the source, must be valid. 1133 * @param length The length within the source to be processed, must be valid. 1134 * @return true if altered. 1135 * @throws IllegalArgumentException if variable is not found when its allowed to throw exception. 1136 */ 1137 public boolean replaceIn(final TextStringBuilder source, final int offset, final int length) { 1138 if (source == null) { 1139 return false; 1140 } 1141 return substitute(source, offset, length); 1142 } 1143 1144 /** 1145 * Internal method that resolves the value of a variable. 1146 * <p> 1147 * Most users of this class do not need to call this method. This method is called automatically by the substitution 1148 * process. 1149 * </p> 1150 * <p> 1151 * Writers of subclasses can override this method if they need to alter how each substitution occurs. The method is 1152 * passed the variable's name and must return the corresponding value. This implementation uses the 1153 * {@link #getStringLookup()} with the variable's name as the key. 1154 * </p> 1155 * 1156 * @param variableName The name of the variable, not null. 1157 * @param buf The buffer where the substitution is occurring, not null. 1158 * @param startPos The start position of the variable including the prefix, valid. 1159 * @param endPos The end position of the variable including the suffix, valid. 1160 * @return The variable's value or {@code null} if the variable is unknown. 1161 */ 1162 protected String resolveVariable(final String variableName, final TextStringBuilder buf, final int startPos, 1163 final int endPos) { 1164 final StringLookup resolver = getStringLookup(); 1165 if (resolver == null) { 1166 return null; 1167 } 1168 return resolver.apply(variableName); 1169 } 1170 1171 /** 1172 * Sets a flag whether substitution is done in variable values (recursive). 1173 * 1174 * @param disableSubstitutionInValues true if substitution in variable value are disabled. 1175 * @return {@code this} instance. 1176 */ 1177 public StringSubstitutor setDisableSubstitutionInValues(final boolean disableSubstitutionInValues) { 1178 this.disableSubstitutionInValues = disableSubstitutionInValues; 1179 return this; 1180 } 1181 1182 /** 1183 * Sets a flag whether substitution is done in variable names. If set to <strong>true</strong>, the names of variables can 1184 * contain other variables which are processed first before the original variable is evaluated, e.g. 1185 * {@code ${jre-${java.version}}}. The default value is <strong>false</strong>. 1186 * 1187 * @param enableSubstitutionInVariables The new value of the flag. 1188 * @return {@code this} instance. 1189 */ 1190 public StringSubstitutor setEnableSubstitutionInVariables(final boolean enableSubstitutionInVariables) { 1191 this.enableSubstitutionInVariables = enableSubstitutionInVariables; 1192 return this; 1193 } 1194 1195 /** 1196 * Sets a flag whether exception should be thrown if any variable is undefined. 1197 * 1198 * @param failOnUndefinedVariable true if exception should be thrown on undefined variable. 1199 * @return {@code this} instance. 1200 */ 1201 public StringSubstitutor setEnableUndefinedVariableException(final boolean failOnUndefinedVariable) { 1202 this.failOnUndefinedVariable = failOnUndefinedVariable; 1203 return this; 1204 } 1205 1206 /** 1207 * Sets the escape character. If this character is placed before a variable reference in the source text, this 1208 * variable will be ignored. 1209 * 1210 * @param escapeChar The escape character (0 for disabling escaping). 1211 * @return {@code this} instance. 1212 */ 1213 public StringSubstitutor setEscapeChar(final char escapeChar) { 1214 this.escapeChar = escapeChar; 1215 return this; 1216 } 1217 1218 /** 1219 * Sets a flag controlling whether escapes are preserved during substitution. If set to <strong>true</strong>, the escape 1220 * character is retained during substitution (e.g. {@code $${this-is-escaped}} remains {@code $${this-is-escaped}}). 1221 * If set to <strong>false</strong>, the escape character is removed during substitution (e.g. {@code $${this-is-escaped}} 1222 * becomes {@code ${this-is-escaped}}). The default value is <strong>false</strong> 1223 * 1224 * @param preserveEscapes true if escapes are to be preserved. 1225 * @return {@code this} instance. 1226 */ 1227 public StringSubstitutor setPreserveEscapes(final boolean preserveEscapes) { 1228 this.preserveEscapes = preserveEscapes; 1229 return this; 1230 } 1231 1232 /** 1233 * Sets the variable default value delimiter to use. 1234 * <p> 1235 * The variable default value delimiter is the character or characters that delimit the variable name and the 1236 * variable default value. This method allows a single character variable default value delimiter to be easily set. 1237 * </p> 1238 * 1239 * @param valueDelimiter The variable default value delimiter character to use. 1240 * @return {@code this} instance. 1241 */ 1242 public StringSubstitutor setValueDelimiter(final char valueDelimiter) { 1243 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.charMatcher(valueDelimiter)); 1244 } 1245 1246 /** 1247 * Sets the variable default value delimiter to use. 1248 * <p> 1249 * The variable default value delimiter is the character or characters that delimit the variable name and the 1250 * variable default value. This method allows a string variable default value delimiter to be easily set. 1251 * </p> 1252 * <p> 1253 * If the {@code valueDelimiter} is null or empty string, then the variable default value resolution becomes 1254 * disabled. 1255 * </p> 1256 * 1257 * @param valueDelimiter The variable default value delimiter string to use, may be null or empty. 1258 * @return {@code this} instance. 1259 */ 1260 public StringSubstitutor setValueDelimiter(final String valueDelimiter) { 1261 if (valueDelimiter == null || valueDelimiter.isEmpty()) { 1262 setValueDelimiterMatcher(null); 1263 return this; 1264 } 1265 return setValueDelimiterMatcher(StringMatcherFactory.INSTANCE.stringMatcher(valueDelimiter)); 1266 } 1267 1268 /** 1269 * Sets the variable default value delimiter matcher to use. 1270 * <p> 1271 * The variable default value delimiter is the character or characters that delimit the variable name and the 1272 * variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default 1273 * value delimiter matches. 1274 * </p> 1275 * <p> 1276 * If the {@code valueDelimiterMatcher} is null, then the variable default value resolution becomes disabled. 1277 * </p> 1278 * 1279 * @param valueDelimiterMatcher variable default value delimiter matcher to use, may be null. 1280 * @return {@code this} instance. 1281 */ 1282 public StringSubstitutor setValueDelimiterMatcher(final StringMatcher valueDelimiterMatcher) { 1283 this.valueDelimiterMatcher = valueDelimiterMatcher; 1284 return this; 1285 } 1286 1287 /** 1288 * Sets the variable prefix to use. 1289 * <p> 1290 * The variable prefix is the character or characters that identify the start of a variable. This method allows a 1291 * single character prefix to be easily set. 1292 * </p> 1293 * 1294 * @param prefix The prefix character to use. 1295 * @return {@code this} instance. 1296 */ 1297 public StringSubstitutor setVariablePrefix(final char prefix) { 1298 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.charMatcher(prefix)); 1299 } 1300 1301 /** 1302 * Sets the variable prefix to use. 1303 * <p> 1304 * The variable prefix is the character or characters that identify the start of a variable. This method allows a 1305 * string prefix to be easily set. 1306 * </p> 1307 * 1308 * @param prefix The prefix for variables, not null. 1309 * @return {@code this} instance. 1310 * @throws IllegalArgumentException if the prefix is null. 1311 */ 1312 public StringSubstitutor setVariablePrefix(final String prefix) { 1313 Validate.isTrue(prefix != null, "Variable prefix must not be null!"); 1314 return setVariablePrefixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(prefix)); 1315 } 1316 1317 /** 1318 * Sets the variable prefix matcher currently in use. 1319 * <p> 1320 * The variable prefix is the character or characters that identify the start of a variable. This prefix is 1321 * expressed in terms of a matcher allowing advanced prefix matches. 1322 * </p> 1323 * 1324 * @param prefixMatcher The prefix matcher to use, null ignored. 1325 * @return {@code this} instance. 1326 * @throws IllegalArgumentException if the prefix matcher is null. 1327 */ 1328 public StringSubstitutor setVariablePrefixMatcher(final StringMatcher prefixMatcher) { 1329 Validate.isTrue(prefixMatcher != null, "Variable prefix matcher must not be null!"); 1330 this.prefixMatcher = prefixMatcher; 1331 return this; 1332 } 1333 1334 /** 1335 * Sets the VariableResolver that is used to lookup variables. 1336 * 1337 * @param variableResolver The VariableResolver. 1338 * @return {@code this} instance. 1339 */ 1340 public StringSubstitutor setVariableResolver(final StringLookup variableResolver) { 1341 this.variableResolver = variableResolver; 1342 return this; 1343 } 1344 1345 /** 1346 * Sets the variable suffix to use. 1347 * <p> 1348 * The variable suffix is the character or characters that identify the end of a variable. This method allows a 1349 * single character suffix to be easily set. 1350 * </p> 1351 * 1352 * @param suffix The suffix character to use. 1353 * @return {@code this} instance. 1354 */ 1355 public StringSubstitutor setVariableSuffix(final char suffix) { 1356 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.charMatcher(suffix)); 1357 } 1358 1359 /** 1360 * Sets the variable suffix to use. 1361 * <p> 1362 * The variable suffix is the character or characters that identify the end of a variable. This method allows a 1363 * string suffix to be easily set. 1364 * </p> 1365 * 1366 * @param suffix The suffix for variables, not null. 1367 * @return {@code this} instance. 1368 * @throws IllegalArgumentException if the suffix is null. 1369 */ 1370 public StringSubstitutor setVariableSuffix(final String suffix) { 1371 Validate.isTrue(suffix != null, "Variable suffix must not be null!"); 1372 return setVariableSuffixMatcher(StringMatcherFactory.INSTANCE.stringMatcher(suffix)); 1373 } 1374 1375 /** 1376 * Sets the variable suffix matcher currently in use. 1377 * <p> 1378 * The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed 1379 * in terms of a matcher allowing advanced suffix matches. 1380 * </p> 1381 * 1382 * @param suffixMatcher The suffix matcher to use, null ignored. 1383 * @return {@code this} instance. 1384 * @throws IllegalArgumentException if the suffix matcher is null. 1385 */ 1386 public StringSubstitutor setVariableSuffixMatcher(final StringMatcher suffixMatcher) { 1387 Validate.isTrue(suffixMatcher != null, "Variable suffix matcher must not be null!"); 1388 this.suffixMatcher = suffixMatcher; 1389 return this; 1390 } 1391 1392 /** 1393 * Internal method that substitutes the variables. 1394 * <p> 1395 * Most users of this class do not need to call this method. This method will be called automatically by another 1396 * (public) method. 1397 * </p> 1398 * <p> 1399 * Writers of subclasses can override this method if they need access to the substitution process at the start or 1400 * end. 1401 * </p> 1402 * 1403 * @param builder The string builder to substitute into, not null. 1404 * @param offset The start offset within the builder, must be valid. 1405 * @param length The length within the builder to be processed, must be valid. 1406 * @return true if altered. 1407 */ 1408 protected boolean substitute(final TextStringBuilder builder, final int offset, final int length) { 1409 return substitute(builder, offset, length, null).altered; 1410 } 1411 1412 /** 1413 * Recursive handler for multiple levels of interpolation. This is the main interpolation method, which resolves the values of all variable references 1414 * contained in the passed in text. 1415 * 1416 * @param builder The string builder to substitute into, not null. 1417 * @param offset The start offset within the builder, must be valid. 1418 * @param length The length within the builder to be processed, must be valid. 1419 * @param priorVariables The stack keeping track of the replaced variables, may be null. 1420 * @return The result. 1421 * @throws IllegalArgumentException if variable is not found and <code>isEnableUndefinedVariableException() == true</code>. 1422 * @since 1.9 1423 */ 1424 private Result substitute(final TextStringBuilder builder, final int offset, final int length, List<String> priorVariables) { 1425 Objects.requireNonNull(builder, "builder"); 1426 final StringMatcher prefixMatcher = getVariablePrefixMatcher(); 1427 final StringMatcher suffixMatcher = getVariableSuffixMatcher(); 1428 final char escapeCh = getEscapeChar(); 1429 final StringMatcher valueDelimMatcher = getValueDelimiterMatcher(); 1430 final boolean substitutionInVariablesEnabled = isEnableSubstitutionInVariables(); 1431 final boolean substitutionInValuesDisabled = isDisableSubstitutionInValues(); 1432 final boolean undefinedVariableException = isEnableUndefinedVariableException(); 1433 final boolean preserveEscapes = isPreserveEscapes(); 1434 boolean altered = false; 1435 int lengthChange = 0; 1436 int bufEnd = offset + length; 1437 int pos = offset; 1438 int escPos = -1; 1439 outer: while (pos < bufEnd) { 1440 final int startMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd); 1441 if (startMatchLen == 0) { 1442 pos++; 1443 } else { 1444 // found variable start marker 1445 if (pos > offset && builder.charAt(pos - 1) == escapeCh) { 1446 // escape detected 1447 if (preserveEscapes) { 1448 // keep escape 1449 pos++; 1450 continue; 1451 } 1452 // mark esc ch for deletion if we find a complete variable 1453 escPos = pos - 1; 1454 } 1455 // find suffix 1456 int startPos = pos; 1457 pos += startMatchLen; 1458 int endMatchLen = 0; 1459 int nestedVarCount = 0; 1460 while (pos < bufEnd) { 1461 if (substitutionInVariablesEnabled && prefixMatcher.isMatch(builder, pos, offset, bufEnd) != 0) { 1462 // found a nested variable start 1463 endMatchLen = prefixMatcher.isMatch(builder, pos, offset, bufEnd); 1464 nestedVarCount++; 1465 pos += endMatchLen; 1466 continue; 1467 } 1468 endMatchLen = suffixMatcher.isMatch(builder, pos, offset, bufEnd); 1469 if (endMatchLen == 0) { 1470 pos++; 1471 } else { 1472 // found variable end marker 1473 if (nestedVarCount == 0) { 1474 if (escPos >= 0) { 1475 final boolean escapedVariableStartsWithNestedPrefix = prefixMatcher.isMatch(builder, startPos + startMatchLen, offset, 1476 bufEnd) != 0; 1477 final boolean hasOuterSuffix = hasLaterSuffix(builder, pos + endMatchLen, offset, bufEnd, suffixMatcher); 1478 pos = escapedVariableStartsWithNestedPrefix && !hasOuterSuffix ? escPos : startPos + 1; 1479 // delete escape 1480 builder.deleteCharAt(escPos); 1481 escPos = -1; 1482 lengthChange--; 1483 altered = true; 1484 bufEnd--; 1485 startPos--; 1486 continue outer; 1487 } 1488 // get var name 1489 String varNameExpr = builder.midString(startPos + startMatchLen, pos - startPos - startMatchLen); 1490 if (substitutionInVariablesEnabled) { 1491 final TextStringBuilder bufName = new TextStringBuilder(varNameExpr); 1492 substitute(bufName, 0, bufName.length()); 1493 varNameExpr = bufName.toString(); 1494 } 1495 pos += endMatchLen; 1496 final int endPos = pos; 1497 String varName = varNameExpr; 1498 String varDefaultValue = null; 1499 if (valueDelimMatcher != null) { 1500 final char[] varNameExprChars = varNameExpr.toCharArray(); 1501 int valueDelimiterMatchLen = 0; 1502 for (int i = 0; i < varNameExprChars.length; i++) { 1503 // if there's any nested variable when nested variable substitution disabled, 1504 // then stop resolving name and default value. 1505 if (!substitutionInVariablesEnabled && prefixMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) { 1506 break; 1507 } 1508 if (valueDelimMatcher.isMatch(varNameExprChars, i, 0, varNameExprChars.length) != 0) { 1509 valueDelimiterMatchLen = valueDelimMatcher.isMatch(varNameExprChars, i, 0, varNameExprChars.length); 1510 varName = varNameExpr.substring(0, i); 1511 varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen); 1512 break; 1513 } 1514 } 1515 } 1516 // on the first call initialize priorVariables 1517 if (priorVariables == null) { 1518 priorVariables = new ArrayList<>(); 1519 priorVariables.add(builder.midString(offset, length)); 1520 } 1521 // handle cyclic substitution 1522 checkCyclicSubstitution(varName, priorVariables); 1523 priorVariables.add(varName); 1524 // resolve the variable 1525 String varValue = resolveVariable(varName, builder, startPos, endPos); 1526 if (varValue == null) { 1527 varValue = varDefaultValue; 1528 } 1529 if (varValue != null) { 1530 final int varLen = varValue.length(); 1531 builder.replace(startPos, endPos, varValue); 1532 altered = true; 1533 int change = 0; 1534 if (!substitutionInValuesDisabled) { // recursive replace 1535 change = substitute(builder, startPos, varLen, priorVariables).lengthChange; 1536 } 1537 change = change + varLen - (endPos - startPos); 1538 pos += change; 1539 bufEnd += change; 1540 lengthChange += change; 1541 } else if (undefinedVariableException) { 1542 throw new IllegalArgumentException(String.format("Cannot resolve variable '%s' (enableSubstitutionInVariables=%s).", varName, 1543 substitutionInVariablesEnabled)); 1544 } 1545 // remove variable from the cyclic stack 1546 priorVariables.remove(priorVariables.size() - 1); 1547 break; 1548 } 1549 nestedVarCount--; 1550 pos += endMatchLen; 1551 } 1552 } 1553 } 1554 } 1555 return new Result(altered, lengthChange); 1556 } 1557 1558 /** 1559 * Returns a string representation of the object. 1560 * 1561 * @return A string representation of the object. 1562 * @since 1.11.0 1563 */ 1564 @Override 1565 public String toString() { 1566 // @formatter:off 1567 return new StringBuilder() 1568 .append("StringSubstitutor [disableSubstitutionInValues=") 1569 .append(disableSubstitutionInValues) 1570 .append(", enableSubstitutionInVariables=") 1571 .append(enableSubstitutionInVariables) 1572 .append(", enableUndefinedVariableException=") 1573 .append(failOnUndefinedVariable) 1574 .append(", escapeChar=") 1575 .append(escapeChar) 1576 .append(", prefixMatcher=") 1577 .append(prefixMatcher) 1578 .append(", preserveEscapes=") 1579 .append(preserveEscapes) 1580 .append(", suffixMatcher=") 1581 .append(suffixMatcher) 1582 .append(", valueDelimiterMatcher=") 1583 .append(valueDelimiterMatcher) 1584 .append(", variableResolver=") 1585 .append(variableResolver) 1586 .append("]") 1587 .toString(); 1588 // @formatter:on 1589 } 1590}