xpath.class.php

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<?php
/**
 * Php.XPath
 *
 * +======================================================================================================+
 * | A php class for searching an XML document using XPath, and making modifications using a DOM 
 * | style API. Does not require the DOM XML PHP library. 
 * |
 * +======================================================================================================+
 * | What Is XPath:
 * | --------------
 * | - "What SQL is for a relational database, XPath is for an XML document." -- Sam Blum
 * | - "The primary purpose of XPath is to address parts of an XML document. In support of this 
 * |    primary purpose, it also provides basic facilities for manipulting it." -- W3C
 * | 
 * | XPath in action and a very nice intro is under:
 * |    http://www.zvon.org/xxl/XPathTutorial/General/examples.html
 * | Specs Can be found under:
 * |    http://www.w3.org/TR/xpath     W3C XPath Recommendation 
 * |    http://www.w3.org/TR/xpath20   W3C XPath Recommendation 
 * |
 * | NOTE: Most of the XPath-spec has been realized, but not all. Usually this should not be
 * |       problem as the missing part is either rarely used or it's simpler to do with PHP itself.
 * +------------------------------------------------------------------------------------------------------+
 * | Requires PHP version  4.0.5 and up
 * +------------------------------------------------------------------------------------------------------+
 * | Main Active Authors:
 * | --------------------
 * | Nigel Swinson <[e-mail]>
 * |   Started around 2001-07, saved phpxml from near death and renamed to Php.XPath
 * |   Restructured XPath code to stay in line with XPath spec.
 * | Sam Blum <[e-mail]>
 * |   Started around 2001-09 1st major restruct (V2.0) and testbench initiator.   
 * |   2nd (V3.0) major rewrite in 2002-02
 * | Daniel Allen <[e-mail]>
 * |   Started around 2001-10 working to make Php.XPath adhere to specs 
 * | Main Former Author: Michael P. Mehl <[e-mail]>
 * |   Inital creator of V 1.0. Stoped activities around 2001-03        
 * +------------------------------------------------------------------------------------------------------+
 * | Code Structure:
 * | --------------_
 * | The class is split into 3 main objects. To keep usability easy all 3 
 * | objects are in this file (but may be split in 3 file in future).
 * |   +-------------+ 
 * |   |  XPathBase  | XPathBase holds general and debugging functions. 
 * |   +------+------+
 * |          v      
 * |   +-------------+ XPathEngine is the implementation of the W3C XPath spec. It contains the 
 * |   | XPathEngine | XML-import (parser), -export  and can handle xPathQueries. It's a fully 
 * |   +------+------+ functional class but has no functions to modify the XML-document (see following).
 * |          v      
 * |   +-------------+ 
 * |   |    XPath    | XPath extends the functionality with actions to modify the XML-document.
 * |   +-------------+ We tryed to implement a DOM - like interface.
 * +------------------------------------------------------------------------------------------------------+
 * | Usage:
 * | ------
 * | Scroll to the end of this php file and you will find a short sample code to get you started
 * +------------------------------------------------------------------------------------------------------+
 * | Glossary:
 * | ---------
 * | To understand how to use the functions and to pass the right parameters, read following:
 * |     
 * | Document: (full node tree, XML-tree)
 * |     After a XML-source has been imported and parsed, it's stored as a tree of nodes sometimes 
 * |     refered to as 'document'.
 * |     
 * | AbsoluteXPath: (xPath, xPathSet)
 * |     A absolute XPath is a string. It 'points' to *one* node in the XML-document. We use the
 * |     term 'absolute' to emphasise that it is not an xPath-query (see xPathQuery). A valid xPath 
 * |     has the form like '/AAA[1]/BBB[2]/CCC[1]'. Usually functions that require a node (see Node) 
 * |     will also accept an abs. XPath.
 * |     
 * | Node: (node, nodeSet, node-tree)
 * |     Some funtions require or return a node (or a whole node-tree). Nodes are only used with the 
 * |     XPath-interface and have an internal structure. Every node in a XML document has a unique 
 * |     corresponding abs. xPath. That's why public functions that accept a node, will usually also 
 * |     accept a abs. xPath (a string) 'pointing' to an existing node (see absolutXPath).
 * |     
 * | XPathQuery: (xquery, query)
 * |     A xPath-query is a string that is matched against the XML-document. The result of the match 
 * |     is a xPathSet (vector of xPath's). It's always possible to pass a single absoluteXPath 
 * |     instead of a xPath-query. A valid xPathQuery could look like this:
 * |     '//XXX/*[contains(., "foo")]/..' (See the link in 'What Is XPath' to learn more).
 * |     
 * |     
 * +------------------------------------------------------------------------------------------------------+
 * | Internals:
 * | ----------
 * | - The Node Tree
 * |   -------------
 * | A central role of the package is how the XML-data is stored. The whole data is in a node-tree.
 * | A node can be seen as the equvalent to a tag in the XML soure with some extra info.
 * | For instance the following XML 
 * |                        <AAA foo="x">***<BBB/><CCC/>**<BBB/>*</AAA>
 * | Would produce folowing node-tree:
 * |                              'super-root'      <-- $nodeRoot (Very handy)  
 * |                                    |                                           
 * |             'depth' 0            AAA[1]        <-- top node. The 'textParts' of this node would be
 * |                                /   |   \                     'textParts' => array('***','','**','*')
 * |             'depth' 1     BBB[1] CCC[1] BBB[2]               (NOTE: Is always size of child nodes+1)
 * | - The Node
 * |   --------
 * | The node itself is an structure desiged mainly to be used in connection with the interface of PHP.XPath.
 * | That means it's possible for functions to return a sub-node-tree that can be used as input of an other 
 * | PHP.XPath function.
 * | 
 * | The main structure of a node is:
 * |   $node = array(
 * |     'name'        => '',      # The tag name. E.g. In <FOO bar="aaa"/> it would be 'FOO'
 * |     'attributes'  => array(), # The attributes of the tag E.g. In <FOO bar="aaa"/> it would be array('bar'=>'aaa')
 * |     'textParts'   => array(), # Array of text parts surrounding the children E.g. <FOO>aa<A>bb<B/>cc</A>dd</FOO> -> array('aa','bb','cc','dd')
 * |     'childNodes'  => array(), # Array of refences (pointers) to child nodes.
 * |     
 * | For optimisation reasions some additional data is stored in the node too:
 * |     'parentNode'  => NULL     # Reference (pointer) to the parent node (or NULL if it's 'super root')
 * |     'depth'       => 0,       # The tag depth (or tree level) starting with the root tag at 0.
 * |     'pos'         => 0,       # Is the zero-based position this node has in the parent's 'childNodes'-list.
 * |     'contextPos'  => 1,       # Is the one-based position this node has by counting the siblings tags (tags with same name)
 * |     'xpath'       => ''       # Is the abs. XPath to this node.
 * |     'generated_id'=> ''       # The id returned for this node by generate-id() (attribute and text nodes not supported)
 * | 
 * | - The NodeIndex
 * |   -------------
 * | Every node in the tree has an absolute XPath. E.g '/AAA[1]/BBB[2]' the $nodeIndex is a hash array
 * | to all the nodes in the node-tree. The key used is the absolute XPath (a string).
 * |    
 * +------------------------------------------------------------------------------------------------------+
 * | License:
 * | --------
 * | The contents of this file are subject to the Mozilla Public License Version 1.1 (the "License"); 
 * | you may not use this file except in compliance with the License. You may obtain a copy of the 
 * | License at http://www.mozilla.org/MPL/ 
 * | 
 * | Software distributed under the License is distributed on an "AS IS" basis, WITHOUT WARRANTY
 * | OF ANY KIND, either express or implied. See the License for the specific language governing 
 * | rights and limitations under the License. 
 * |
 * | The Original Code is <phpXML/>. 
 * | 
 * | The Initial Developer of the Original Code is Michael P. Mehl. Portions created by Michael 
 * | P. Mehl are Copyright (C) 2001 Michael P. Mehl. All Rights Reserved.
 * |
 * | Contributor(s): N.Swinson / S.Blum / D.Allen
 * | 
 * | Alternatively, the contents of this file may be used under the terms of either of the GNU 
 * | General Public License Version 2 or later (the "GPL"), or the GNU Lesser General Public 
 * | License Version 2.1 or later (the "LGPL"), in which case the provisions of the GPL or the 
 * | LGPL License are applicable instead of those above.  If you wish to allow use of your version 
 * | of this file only under the terms of the GPL or the LGPL License and not to allow others to 
 * | use your version of this file under the MPL, indicate your decision by deleting the 
 * | provisions above and replace them with the notice and other provisions required by the 
 * | GPL or the LGPL License.  If you do not delete the provisions above, a recipient may use 
 * | your version of this file under either the MPL, the GPL or the LGPL License. 
 * | 
 * +======================================================================================================+
 *
 * @author  S.Blum / N.Swinson / D.Allen / (P.Mehl)
 * @link    http://sourceforge.net/projects/phpxpath/
 * @version 3.4
 * @CVS $Id: XPath.class.php,v 1.1 2005/04/15 21:23:31 mschering Exp $
 */

/************************************************************************************************
* ===============================================================================================
*                               X P a t h B a s e  -  Class                                      
* ===============================================================================================
************************************************************************************************/
class XPathBase {
  var $_lastError;
  
  // As debugging of the xml parse is spread across several functions, we need to make this a member.
  var $bDebugXmlParse = FALSE;

  // Used to help navigate through the begin/end debug calls
  var $iDebugNextLinkNumber = 1;
  var $aDebugOpenLinks = array();

  /**
   * Constructor
   */
  function XPathBase() {
    # $this->bDebugXmlParse = TRUE;
    $this->properties['verboseLevel'] = 1;  // 0=silent, 1 and above produce verbose output (an echo to screen). 
    
    if (!isSet($_ENV)) {  // Note: $_ENV introduced in 4.1.0. In earlier versions, use $HTTP_ENV_VARS.
      $_ENV = $GLOBALS['HTTP_ENV_VARS'];
    }
    
    // Windows 95/98 do not support file locking. Detecting OS (Operation System) and setting the 
    // properties['OS_supports_flock'] to FALSE if win 95/98 is detected. 
    // This will surpress the file locking error reported from win 98 users when exportToFile() is called.
    // May have to add more OS's to the list in future (Macs?).
    // ### Note that it's only the FAT and NFS file systems that are really a problem.  NTFS and
    // the latest php libs do support flock()
    $_ENV['OS'] = isSet($_ENV['OS']) ? $_ENV['OS'] : 'Unknown OS';
    switch ($_ENV['OS']) { 
      case 'Windows_95':
      case 'Windows_98':
      case 'Unknown OS':
        // should catch Mac OS X compatible environment 
        if (preg_match('/Darwin/',$_SERVER['SERVER_SOFTWARE'])) { 
           // fall-through 
        } else { 
           $this->properties['OS_supports_flock'] = FALSE; 
           break; 
        }
      default:
        $this->properties['OS_supports_flock'] = TRUE;
    }
  }
  
  
  /**
   * Resets the object so it's able to take a new xml sting/file
   *
   * Constructing objects is slow.  If you can, reuse ones that you have used already
   * by using this reset() function.
   */
  function reset() {
    $this->_lastError   = '';
  }
  
  //-----------------------------------------------------------------------------------------
  // XPathBase                    ------  Helpers  ------                                    
  //-----------------------------------------------------------------------------------------
  
  /**
   * This method checks the right amount and match of brackets
   *
   * @param     $term (string) String in which is checked.
   * @return          (bool)   TRUE: OK / FALSE: KO  
   */
  function _bracketsCheck($term) {
    $leng = strlen($term);
    $brackets = 0;
    $bracketMisscount = $bracketMissmatsh = FALSE;
    $stack = array();
    for ($i=0; $i<$leng; $i++) {
      switch ($term[$i]) {
        case '(' : 
        case '[' : 
          $stack[$brackets] = $term[$i]; 
          $brackets++; 
          break;
        case ')': 
          $brackets--;
          if ($brackets<0) {
            $bracketMisscount = TRUE;
            break 2;
          }
          if ($stack[$brackets] != '(') {
            $bracketMissmatsh = TRUE;
            break 2;
          }
          break;
        case ']' : 
          $brackets--;
          if ($brackets<0) {
            $bracketMisscount = TRUE;
            break 2;
          }
          if ($stack[$brackets] != '[') {
            $bracketMissmatsh = TRUE;
            break 2;
          }
          break;
      }
    }
    // Check whether we had a valid number of brackets.
    if ($brackets != 0) $bracketMisscount = TRUE;
    if ($bracketMisscount || $bracketMissmatsh) {
      return FALSE;
    }
    return TRUE;
  }
  
  /**
   * Looks for a string within another string -- BUT the search-string must be located *outside* of any brackets.
   *
   * This method looks for a string within another string. Brackets in the
   * string the method is looking through will be respected, which means that
   * only if the string the method is looking for is located outside of
   * brackets, the search will be successful.
   *
   * @param     $term       (string) String in which the search shall take place.
   * @param     $expression (string) String that should be searched.
   * @return                (int)    This method returns -1 if no string was found, 
   *                                 otherwise the offset at which the string was found.
   */
  function _searchString($term, $expression) {
    $bracketCounter = 0; // Record where we are in the brackets. 
    $leng = strlen($term);
    $exprLeng = strlen($expression);
    for ($i=0; $i<$leng; $i++) {
      $char = $term[$i];
      if ($char=='(' || $char=='[') {
        $bracketCounter++;
        continue;
      }
      elseif ($char==')' || $char==']') {
        $bracketCounter--;