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 * http://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.configuration2.tree; 018 019import java.util.Iterator; 020import java.util.NoSuchElementException; 021 022import org.apache.commons.lang3.StringUtils; 023 024/** 025 * <p> 026 * A simple class that supports creation of and iteration on configuration keys 027 * supported by a {@link DefaultExpressionEngine} object. 028 * </p> 029 * <p> 030 * For key creation the class works similar to a StringBuffer: There are several 031 * {@code appendXXXX()} methods with which single parts of a key can be 032 * constructed. All these methods return a reference to the actual object so 033 * they can be written in a chain. When using this methods the exact syntax for 034 * keys need not be known. 035 * </p> 036 * <p> 037 * This class also defines a specialized iterator for configuration keys. With 038 * such an iterator a key can be tokenized into its single parts. For each part 039 * it can be checked whether it has an associated index. 040 * </p> 041 * <p> 042 * Instances of this class are always associated with an instance of 043 * {@link DefaultExpressionEngine}, from which the current 044 * delimiters are obtained. So key creation and parsing is specific to this 045 * associated expression engine. 046 * </p> 047 * 048 * @since 1.3 049 * @author <a 050 * href="http://commons.apache.org/configuration/team-list.html">Commons 051 * Configuration team</a> 052 * @version $Id: DefaultConfigurationKey.java 1842194 2018-09-27 22:24:23Z ggregory $ 053 */ 054public class DefaultConfigurationKey 055{ 056 /** Constant for the initial StringBuffer size. */ 057 private static final int INITIAL_SIZE = 32; 058 059 /** Stores a reference to the associated expression engine. */ 060 private final DefaultExpressionEngine expressionEngine; 061 062 /** Holds a buffer with the so far created key. */ 063 private final StringBuilder keyBuffer; 064 065 /** 066 * Creates a new instance of {@code DefaultConfigurationKey} and sets 067 * the associated expression engine. 068 * 069 * @param engine the expression engine (must not be <b>null</b>) 070 * @throws IllegalArgumentException if the expression engine is <b>null</b> 071 */ 072 public DefaultConfigurationKey(final DefaultExpressionEngine engine) 073 { 074 this(engine, null); 075 } 076 077 /** 078 * Creates a new instance of {@code DefaultConfigurationKey} and sets the 079 * associated expression engine and an initial key. 080 * 081 * @param engine the expression engine (must not be <b>null</b>) 082 * @param key the key to be wrapped 083 * @throws IllegalArgumentException if the expression engine is <b>null</b> 084 */ 085 public DefaultConfigurationKey(final DefaultExpressionEngine engine, final String key) 086 { 087 if (engine == null) 088 { 089 throw new IllegalArgumentException( 090 "Expression engine must not be null!"); 091 } 092 expressionEngine = engine; 093 if (key != null) 094 { 095 keyBuffer = new StringBuilder(trim(key)); 096 } 097 else 098 { 099 keyBuffer = new StringBuilder(INITIAL_SIZE); 100 } 101 } 102 103 /** 104 * Returns the associated default expression engine. 105 * 106 * @return the associated expression engine 107 */ 108 public DefaultExpressionEngine getExpressionEngine() 109 { 110 return expressionEngine; 111 } 112 113 /** 114 * Appends the name of a property to this key. If necessary, a property 115 * delimiter will be added. If the boolean argument is set to <b>true</b>, 116 * property delimiters contained in the property name will be escaped. 117 * 118 * @param property the name of the property to be added 119 * @param escape a flag if property delimiters in the passed in property name 120 * should be escaped 121 * @return a reference to this object 122 */ 123 public DefaultConfigurationKey append(final String property, final boolean escape) 124 { 125 String key; 126 if (escape && property != null) 127 { 128 key = escapeDelimiters(property); 129 } 130 else 131 { 132 key = property; 133 } 134 key = trim(key); 135 136 if (keyBuffer.length() > 0 && !isAttributeKey(property) 137 && key.length() > 0) 138 { 139 keyBuffer.append(getSymbols().getPropertyDelimiter()); 140 } 141 142 keyBuffer.append(key); 143 return this; 144 } 145 146 /** 147 * Appends the name of a property to this key. If necessary, a property 148 * delimiter will be added. Property delimiters in the given string will not 149 * be escaped. 150 * 151 * @param property the name of the property to be added 152 * @return a reference to this object 153 */ 154 public DefaultConfigurationKey append(final String property) 155 { 156 return append(property, false); 157 } 158 159 /** 160 * Appends an index to this configuration key. 161 * 162 * @param index the index to be appended 163 * @return a reference to this object 164 */ 165 public DefaultConfigurationKey appendIndex(final int index) 166 { 167 keyBuffer.append(getSymbols().getIndexStart()); 168 keyBuffer.append(index); 169 keyBuffer.append(getSymbols().getIndexEnd()); 170 return this; 171 } 172 173 /** 174 * Appends an attribute to this configuration key. 175 * 176 * @param attr the name of the attribute to be appended 177 * @return a reference to this object 178 */ 179 public DefaultConfigurationKey appendAttribute(final String attr) 180 { 181 keyBuffer.append(constructAttributeKey(attr)); 182 return this; 183 } 184 185 /** 186 * Returns the actual length of this configuration key. 187 * 188 * @return the length of this key 189 */ 190 public int length() 191 { 192 return keyBuffer.length(); 193 } 194 195 /** 196 * Sets the new length of this configuration key. With this method it is 197 * possible to truncate the key, e.g. to return to a state prior calling 198 * some {@code append()} methods. The semantic is the same as the 199 * {@code setLength()} method of {@code StringBuilder}. 200 * 201 * @param len the new length of the key 202 */ 203 public void setLength(final int len) 204 { 205 keyBuffer.setLength(len); 206 } 207 /** 208 * Returns a configuration key object that is initialized with the part 209 * of the key that is common to this key and the passed in key. 210 * 211 * @param other the other key 212 * @return a key object with the common key part 213 */ 214 public DefaultConfigurationKey commonKey(final DefaultConfigurationKey other) 215 { 216 if (other == null) 217 { 218 throw new IllegalArgumentException("Other key must no be null!"); 219 } 220 221 final DefaultConfigurationKey result = new DefaultConfigurationKey(getExpressionEngine()); 222 final KeyIterator it1 = iterator(); 223 final KeyIterator it2 = other.iterator(); 224 225 while (it1.hasNext() && it2.hasNext() && partsEqual(it1, it2)) 226 { 227 if (it1.isAttribute()) 228 { 229 result.appendAttribute(it1.currentKey()); 230 } 231 else 232 { 233 result.append(it1.currentKey()); 234 if (it1.hasIndex) 235 { 236 result.appendIndex(it1.getIndex()); 237 } 238 } 239 } 240 241 return result; 242 } 243 244 /** 245 * Returns the "difference key" to a given key. This value 246 * is the part of the passed in key that differs from this key. There is 247 * the following relation: 248 * {@code other = key.commonKey(other) + key.differenceKey(other)} 249 * for an arbitrary configuration key {@code key}. 250 * 251 * @param other the key for which the difference is to be calculated 252 * @return the difference key 253 */ 254 public DefaultConfigurationKey differenceKey(final DefaultConfigurationKey other) 255 { 256 final DefaultConfigurationKey common = commonKey(other); 257 final DefaultConfigurationKey result = new DefaultConfigurationKey(getExpressionEngine()); 258 259 if (common.length() < other.length()) 260 { 261 final String k = other.toString().substring(common.length()); 262 // skip trailing delimiters 263 int i = 0; 264 while (i < k.length() 265 && String.valueOf(k.charAt(i)).equals( 266 getSymbols().getPropertyDelimiter())) 267 { 268 i++; 269 } 270 271 if (i < k.length()) 272 { 273 result.append(k.substring(i)); 274 } 275 } 276 277 return result; 278 } 279 280 /** 281 * Checks if two {@code ConfigurationKey} objects are equal. Two instances 282 * of this class are considered equal if they have the same content (i.e. 283 * their internal string representation is equal). The expression engine 284 * property is not taken into account. 285 * 286 * @param obj the object to compare 287 * @return a flag if both objects are equal 288 */ 289 @Override 290 public boolean equals(final Object obj) 291 { 292 if (this == obj) 293 { 294 return true; 295 } 296 if (!(obj instanceof DefaultConfigurationKey)) 297 { 298 return false; 299 } 300 301 final DefaultConfigurationKey c = (DefaultConfigurationKey) obj; 302 return keyBuffer.toString().equals(c.toString()); 303 } 304 305 /** 306 * Returns the hash code for this object. 307 * 308 * @return the hash code 309 */ 310 @Override 311 public int hashCode() 312 { 313 return String.valueOf(keyBuffer).hashCode(); 314 } 315 316 /** 317 * Returns a string representation of this object. This is the configuration 318 * key as a plain string. 319 * 320 * @return a string for this object 321 */ 322 @Override 323 public String toString() 324 { 325 return keyBuffer.toString(); 326 } 327 328 /** 329 * Tests if the specified key represents an attribute according to the 330 * current expression engine. 331 * 332 * @param key the key to be checked 333 * @return <b>true</b> if this is an attribute key, <b>false</b> otherwise 334 */ 335 public boolean isAttributeKey(final String key) 336 { 337 if (key == null) 338 { 339 return false; 340 } 341 342 return key.startsWith(getSymbols().getAttributeStart()) 343 && (getSymbols().getAttributeEnd() == null || key 344 .endsWith(getSymbols().getAttributeEnd())); 345 } 346 347 /** 348 * Decorates the given key so that it represents an attribute. Adds special 349 * start and end markers. The passed in string will be modified only if does 350 * not already represent an attribute. 351 * 352 * @param key the key to be decorated 353 * @return the decorated attribute key 354 */ 355 public String constructAttributeKey(final String key) 356 { 357 if (key == null) 358 { 359 return StringUtils.EMPTY; 360 } 361 if (isAttributeKey(key)) 362 { 363 return key; 364 } 365 final StringBuilder buf = new StringBuilder(); 366 buf.append(getSymbols().getAttributeStart()).append(key); 367 if (getSymbols().getAttributeEnd() != null) 368 { 369 buf.append(getSymbols().getAttributeEnd()); 370 } 371 return buf.toString(); 372 } 373 374 /** 375 * Extracts the name of the attribute from the given attribute key. This 376 * method removes the attribute markers - if any - from the specified key. 377 * 378 * @param key the attribute key 379 * @return the name of the corresponding attribute 380 */ 381 public String attributeName(final String key) 382 { 383 return isAttributeKey(key) ? removeAttributeMarkers(key) : key; 384 } 385 386 /** 387 * Removes leading property delimiters from the specified key. 388 * 389 * @param key the key 390 * @return the key with removed leading property delimiters 391 */ 392 public String trimLeft(final String key) 393 { 394 if (key == null) 395 { 396 return StringUtils.EMPTY; 397 } 398 String result = key; 399 while (hasLeadingDelimiter(result)) 400 { 401 result = result.substring(getSymbols() 402 .getPropertyDelimiter().length()); 403 } 404 return result; 405 } 406 407 /** 408 * Removes trailing property delimiters from the specified key. 409 * 410 * @param key the key 411 * @return the key with removed trailing property delimiters 412 */ 413 public String trimRight(final String key) 414 { 415 if (key == null) 416 { 417 return StringUtils.EMPTY; 418 } 419 String result = key; 420 while (hasTrailingDelimiter(result)) 421 { 422 result = result 423 .substring(0, result.length() 424 - getSymbols().getPropertyDelimiter() 425 .length()); 426 } 427 return result; 428 } 429 430 /** 431 * Removes delimiters at the beginning and the end of the specified key. 432 * 433 * @param key the key 434 * @return the key with removed property delimiters 435 */ 436 public String trim(final String key) 437 { 438 return trimRight(trimLeft(key)); 439 } 440 441 /** 442 * Returns an iterator for iterating over the single components of this 443 * configuration key. 444 * 445 * @return an iterator for this key 446 */ 447 public KeyIterator iterator() 448 { 449 return new KeyIterator(); 450 } 451 452 /** 453 * Helper method that checks if the specified key ends with a property 454 * delimiter. 455 * 456 * @param key the key to check 457 * @return a flag if there is a trailing delimiter 458 */ 459 private boolean hasTrailingDelimiter(final String key) 460 { 461 return key.endsWith(getSymbols().getPropertyDelimiter()) 462 && (getSymbols().getEscapedDelimiter() == null || !key 463 .endsWith(getSymbols().getEscapedDelimiter())); 464 } 465 466 /** 467 * Helper method that checks if the specified key starts with a property 468 * delimiter. 469 * 470 * @param key the key to check 471 * @return a flag if there is a leading delimiter 472 */ 473 private boolean hasLeadingDelimiter(final String key) 474 { 475 return key.startsWith(getSymbols().getPropertyDelimiter()) 476 && (getSymbols().getEscapedDelimiter() == null || !key 477 .startsWith(getSymbols().getEscapedDelimiter())); 478 } 479 480 /** 481 * Helper method for removing attribute markers from a key. 482 * 483 * @param key the key 484 * @return the key with removed attribute markers 485 */ 486 private String removeAttributeMarkers(final String key) 487 { 488 return key 489 .substring( 490 getSymbols().getAttributeStart().length(), 491 key.length() 492 - ((getSymbols().getAttributeEnd() != null) ? getSymbols() 493 .getAttributeEnd().length() 494 : 0)); 495 } 496 497 /** 498 * Unescapes the delimiters in the specified string. 499 * 500 * @param key the key to be unescaped 501 * @return the unescaped key 502 */ 503 private String unescapeDelimiters(final String key) 504 { 505 return (getSymbols().getEscapedDelimiter() == null) ? key 506 : StringUtils.replace(key, getSymbols() 507 .getEscapedDelimiter(), getSymbols() 508 .getPropertyDelimiter()); 509 } 510 511 /** 512 * Returns the symbols object from the associated expression engine. 513 * 514 * @return the {@code DefaultExpressionEngineSymbols} 515 */ 516 private DefaultExpressionEngineSymbols getSymbols() 517 { 518 return getExpressionEngine().getSymbols(); 519 } 520 521 /** 522 * Escapes the delimiters in the specified string. 523 * 524 * @param key the key to be escaped 525 * @return the escaped key 526 */ 527 private String escapeDelimiters(final String key) 528 { 529 return (getSymbols().getEscapedDelimiter() == null || key 530 .indexOf(getSymbols().getPropertyDelimiter()) < 0) ? key 531 : StringUtils.replace(key, getSymbols() 532 .getPropertyDelimiter(), getSymbols() 533 .getEscapedDelimiter()); 534 } 535 536 /** 537 * Helper method for comparing two key parts. 538 * 539 * @param it1 the iterator with the first part 540 * @param it2 the iterator with the second part 541 * @return a flag if both parts are equal 542 */ 543 private static boolean partsEqual(final KeyIterator it1, final KeyIterator it2) 544 { 545 return it1.nextKey().equals(it2.nextKey()) 546 && it1.getIndex() == it2.getIndex() 547 && it1.isAttribute() == it2.isAttribute(); 548 } 549 550 /** 551 * A specialized iterator class for tokenizing a configuration key. This 552 * class implements the normal iterator interface. In addition it provides 553 * some specific methods for configuration keys. 554 */ 555 public class KeyIterator implements Iterator<Object>, Cloneable 556 { 557 /** Stores the current key name. */ 558 private String current; 559 560 /** Stores the start index of the actual token. */ 561 private int startIndex; 562 563 /** Stores the end index of the actual token. */ 564 private int endIndex; 565 566 /** Stores the index of the actual property if there is one. */ 567 private int indexValue; 568 569 /** Stores a flag if the actual property has an index. */ 570 private boolean hasIndex; 571 572 /** Stores a flag if the actual property is an attribute. */ 573 private boolean attribute; 574 575 /** 576 * Returns the next key part of this configuration key. This is a short 577 * form of {@code nextKey(false)}. 578 * 579 * @return the next key part 580 */ 581 public String nextKey() 582 { 583 return nextKey(false); 584 } 585 586 /** 587 * Returns the next key part of this configuration key. The boolean 588 * parameter indicates wheter a decorated key should be returned. This 589 * affects only attribute keys: if the parameter is <b>false</b>, the 590 * attribute markers are stripped from the key; if it is <b>true</b>, 591 * they remain. 592 * 593 * @param decorated a flag if the decorated key is to be returned 594 * @return the next key part 595 */ 596 public String nextKey(final boolean decorated) 597 { 598 if (!hasNext()) 599 { 600 throw new NoSuchElementException("No more key parts!"); 601 } 602 603 hasIndex = false; 604 indexValue = -1; 605 final String key = findNextIndices(); 606 607 current = key; 608 hasIndex = checkIndex(key); 609 attribute = checkAttribute(current); 610 611 return currentKey(decorated); 612 } 613 614 /** 615 * Checks if there is a next element. 616 * 617 * @return a flag if there is a next element 618 */ 619 @Override 620 public boolean hasNext() 621 { 622 return endIndex < keyBuffer.length(); 623 } 624 625 /** 626 * Returns the next object in the iteration. 627 * 628 * @return the next object 629 */ 630 @Override 631 public Object next() 632 { 633 return nextKey(); 634 } 635 636 /** 637 * Removes the current object in the iteration. This method is not 638 * supported by this iterator type, so an exception is thrown. 639 */ 640 @Override 641 public void remove() 642 { 643 throw new UnsupportedOperationException("Remove not supported!"); 644 } 645 646 /** 647 * Returns the current key of the iteration (without skipping to the 648 * next element). This is the same key the previous {@code next()} 649 * call had returned. (Short form of {@code currentKey(false)}. 650 * 651 * @return the current key 652 */ 653 public String currentKey() 654 { 655 return currentKey(false); 656 } 657 658 /** 659 * Returns the current key of the iteration (without skipping to the 660 * next element). The boolean parameter indicates wheter a decorated key 661 * should be returned. This affects only attribute keys: if the 662 * parameter is <b>false</b>, the attribute markers are stripped from 663 * the key; if it is <b>true</b>, they remain. 664 * 665 * @param decorated a flag if the decorated key is to be returned 666 * @return the current key 667 */ 668 public String currentKey(final boolean decorated) 669 { 670 return (decorated && !isPropertyKey()) ? constructAttributeKey(current) 671 : current; 672 } 673 674 /** 675 * Returns a flag if the current key is an attribute. This method can be 676 * called after {@code next()}. 677 * 678 * @return a flag if the current key is an attribute 679 */ 680 public boolean isAttribute() 681 { 682 // if attribute emulation mode is active, the last part of a key is 683 // always an attribute key, too 684 return attribute || (isAttributeEmulatingMode() && !hasNext()); 685 } 686 687 /** 688 * Returns a flag whether the current key refers to a property (i.e. is 689 * no special attribute key). Usually this method will return the 690 * opposite of {@code isAttribute()}, but if the delimiters for 691 * normal properties and attributes are set to the same string, it is 692 * possible that both methods return <b>true</b>. 693 * 694 * @return a flag if the current key is a property key 695 * @see #isAttribute() 696 */ 697 public boolean isPropertyKey() 698 { 699 return !attribute; 700 } 701 702 /** 703 * Returns the index value of the current key. If the current key does 704 * not have an index, return value is -1. This method can be called 705 * after {@code next()}. 706 * 707 * @return the index value of the current key 708 */ 709 public int getIndex() 710 { 711 return indexValue; 712 } 713 714 /** 715 * Returns a flag if the current key has an associated index. This 716 * method can be called after {@code next()}. 717 * 718 * @return a flag if the current key has an index 719 */ 720 public boolean hasIndex() 721 { 722 return hasIndex; 723 } 724 725 /** 726 * Creates a clone of this object. 727 * 728 * @return a clone of this object 729 */ 730 @Override 731 public Object clone() 732 { 733 try 734 { 735 return super.clone(); 736 } 737 catch (final CloneNotSupportedException cex) 738 { 739 // should not happen 740 return null; 741 } 742 } 743 744 /** 745 * Helper method for determining the next indices. 746 * 747 * @return the next key part 748 */ 749 private String findNextIndices() 750 { 751 startIndex = endIndex; 752 // skip empty names 753 while (startIndex < length() 754 && hasLeadingDelimiter(keyBuffer.substring(startIndex))) 755 { 756 startIndex += getSymbols().getPropertyDelimiter() 757 .length(); 758 } 759 760 // Key ends with a delimiter? 761 if (startIndex >= length()) 762 { 763 endIndex = length(); 764 startIndex = endIndex - 1; 765 return keyBuffer.substring(startIndex, endIndex); 766 } 767 return nextKeyPart(); 768 } 769 770 /** 771 * Helper method for extracting the next key part. Takes escaping of 772 * delimiter characters into account. 773 * 774 * @return the next key part 775 */ 776 private String nextKeyPart() 777 { 778 int attrIdx = keyBuffer.toString().indexOf( 779 getSymbols().getAttributeStart(), startIndex); 780 if (attrIdx < 0 || attrIdx == startIndex) 781 { 782 attrIdx = length(); 783 } 784 785 int delIdx = nextDelimiterPos(keyBuffer.toString(), startIndex, 786 attrIdx); 787 if (delIdx < 0) 788 { 789 delIdx = attrIdx; 790 } 791 792 endIndex = Math.min(attrIdx, delIdx); 793 return unescapeDelimiters(keyBuffer.substring(startIndex, endIndex)); 794 } 795 796 /** 797 * Searches the next unescaped delimiter from the given position. 798 * 799 * @param key the key 800 * @param pos the start position 801 * @param endPos the end position 802 * @return the position of the next delimiter or -1 if there is none 803 */ 804 private int nextDelimiterPos(final String key, final int pos, final int endPos) 805 { 806 int delimiterPos = pos; 807 boolean found = false; 808 809 do 810 { 811 delimiterPos = key.indexOf(getSymbols() 812 .getPropertyDelimiter(), delimiterPos); 813 if (delimiterPos < 0 || delimiterPos >= endPos) 814 { 815 return -1; 816 } 817 final int escapePos = escapedPosition(key, delimiterPos); 818 if (escapePos < 0) 819 { 820 found = true; 821 } 822 else 823 { 824 delimiterPos = escapePos; 825 } 826 } 827 while (!found); 828 829 return delimiterPos; 830 } 831 832 /** 833 * Checks if a delimiter at the specified position is escaped. If this 834 * is the case, the next valid search position will be returned. 835 * Otherwise the return value is -1. 836 * 837 * @param key the key to check 838 * @param pos the position where a delimiter was found 839 * @return information about escaped delimiters 840 */ 841 private int escapedPosition(final String key, final int pos) 842 { 843 if (getSymbols().getEscapedDelimiter() == null) 844 { 845 // nothing to escape 846 return -1; 847 } 848 final int escapeOffset = escapeOffset(); 849 if (escapeOffset < 0 || escapeOffset > pos) 850 { 851 // No escaping possible at this position 852 return -1; 853 } 854 855 final int escapePos = key.indexOf(getSymbols() 856 .getEscapedDelimiter(), pos - escapeOffset); 857 if (escapePos <= pos && escapePos >= 0) 858 { 859 // The found delimiter is escaped. Next valid search position 860 // is behind the escaped delimiter. 861 return escapePos 862 + getSymbols().getEscapedDelimiter().length(); 863 } 864 return -1; 865 } 866 867 /** 868 * Determines the relative offset of an escaped delimiter in relation to 869 * a delimiter. Depending on the used delimiter and escaped delimiter 870 * tokens the position where to search for an escaped delimiter is 871 * different. If, for instance, the dot character (".") is 872 * used as delimiter, and a doubled dot ("..") as escaped 873 * delimiter, the escaped delimiter starts at the same position as the 874 * delimiter. If the token "\." was used, it would start one 875 * character before the delimiter because the delimiter character 876 * "." is the second character in the escaped delimiter 877 * string. This relation will be determined by this method. For this to 878 * work the delimiter string must be contained in the escaped delimiter 879 * string. 880 * 881 * @return the relative offset of the escaped delimiter in relation to a 882 * delimiter 883 */ 884 private int escapeOffset() 885 { 886 return getSymbols().getEscapedDelimiter().indexOf( 887 getSymbols().getPropertyDelimiter()); 888 } 889 890 /** 891 * Helper method for checking if the passed key is an attribute. If this 892 * is the case, the internal fields will be set. 893 * 894 * @param key the key to be checked 895 * @return a flag if the key is an attribute 896 */ 897 private boolean checkAttribute(final String key) 898 { 899 if (isAttributeKey(key)) 900 { 901 current = removeAttributeMarkers(key); 902 return true; 903 } 904 return false; 905 } 906 907 /** 908 * Helper method for checking if the passed key contains an index. If 909 * this is the case, internal fields will be set. 910 * 911 * @param key the key to be checked 912 * @return a flag if an index is defined 913 */ 914 private boolean checkIndex(final String key) 915 { 916 boolean result = false; 917 918 try 919 { 920 final int idx = key.lastIndexOf(getSymbols().getIndexStart()); 921 if (idx > 0) 922 { 923 final int endidx = key.indexOf(getSymbols().getIndexEnd(), 924 idx); 925 926 if (endidx > idx + 1) 927 { 928 indexValue = Integer.parseInt(key.substring(idx + 1, endidx)); 929 current = key.substring(0, idx); 930 result = true; 931 } 932 } 933 } 934 catch (final NumberFormatException nfe) 935 { 936 result = false; 937 } 938 939 return result; 940 } 941 942 /** 943 * Returns a flag whether attributes are marked the same way as normal 944 * property keys. We call this the "attribute emulating mode". 945 * When navigating through node hierarchies it might be convenient to 946 * treat attributes the same way than other child nodes, so an 947 * expression engine supports to set the attribute markers to the same 948 * value than the property delimiter. If this is the case, some special 949 * checks have to be performed. 950 * 951 * @return a flag if attributes and normal property keys are treated the 952 * same way 953 */ 954 private boolean isAttributeEmulatingMode() 955 { 956 return getSymbols().getAttributeEnd() == null 957 && StringUtils.equals(getSymbols() 958 .getPropertyDelimiter(), getSymbols() 959 .getAttributeStart()); 960 } 961 } 962}