XPATH

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XPATH

• http//www.zvon.org/xxl/XPathTutorial/General/exam
  ples.html

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• XPath syntax is similar to file system. If the
  path starts with the slash / , then it represents
  an absolute path to the required element.  
• /AAA (Select the root element AAA)
•      ltAAAgt           ltBBB/gt           ltCCC/gt
            ltBBB/gt           ltBBB/gt
            ltDDDgt                ltBBB/gt
            lt/DDDgt           ltCCC/gt      lt/AAAgt

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• /AAA/CCC
• Select all elements CCC which are children of the
  root element AAA
•      ltAAAgt           ltBBB/gt           ltCCC/gt
            ltBBB/gt           ltBBB/gt
            ltDDDgt                ltBBB/gt
            lt/DDDgt           ltCCC/gt      lt/AAAgt

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• /AAA/DDD/BBB
• Select all elements BBB which are children of DDD
  which are children of the root element AAA
•      ltAAAgt           ltBBB/gt           ltCCC/gt
            ltBBB/gt           ltBBB/gt
            ltDDDgt                ltBBB/gt
            lt/DDDgt           ltCCC/gt      lt/AAAgt

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• If the path starts with // then all elements in
  the document which fulfill following criteria are
  selected. 
• //BBB
• Select all elements BBB
•      ltAAAgt           ltBBB/gt           ltCCC/gt
            ltBBB/gt           ltDDDgt               
  ltBBB/gt          lt/DDDgt           ltCCCgt         
        ltDDDgt                    ltBBB/gt           
           ltBBB/gt               lt/DDDgt          lt/
  CCCgt      lt/AAAgt

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• //DDD/BBB
• Select all elements BBB which are children of DDD
•      ltAAAgt           ltBBB/gt           ltCCC/gt
            ltBBB/gt           ltDDDgt               
  ltBBB/gt          lt/DDDgt           ltCCCgt         
        ltDDDgt                    ltBBB/gt           
           ltBBB/gt               lt/DDDgt          lt/
  CCCgt      lt/AAAgt

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• The star selects all elements located by
  preceeding path  /AAA/CCC/DDD/
• Select all elements enclosed by elements
  /AAA/CCC/DDD
• ltAAAgt         
• ltXXXgt               ltDDDgt                  
    ltBBB/gt                    ltBBB/gt              
        ltEEE/gt                    ltFFF/gt          
       lt/DDDgt          lt/XXXgt           ltCCCgt    
             ltDDDgt                    ltBBB/gt      
                ltBBB/gt                    ltEEE/gt  
                    ltFFF/gt               lt/DDDgt   
       

•   lt/CCCgt           ltCCCgt               ltBBBgt   
                   ltBBBgt                         ltB
  BB/gt                    lt/BBBgt               lt/B
  BBgt          lt/CCCgt      lt/AAAgt

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• ////BBB
• Select all elements BBB which have 3 ancestors
•      ltAAAgt           ltXXXgt               ltDDDgt
                      ltBBB/gt                    ltBB
  B/gt                    ltEEE/gt                   
   ltFFF/gt               lt/DDDgt          lt/XXXgt
            ltCCCgt              

•  ltDDDgt                    ltBBB/gt                
      ltBBB/gt                    ltEEE/gt            
          ltFFF/gt               lt/DDDgt          lt/C
  CCgt           ltCCCgt               ltBBBgt        
              ltBBBgt                         ltBBB/gt
                      lt/BBBgt               lt/BBBgt 
           lt/CCCgt      lt/AAAgt

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• //
• Select all elements
•      ltAAAgt           ltXXXgt               ltDDDgt
                      ltBBB/gt                    ltBB
  B/gt                    ltEEE/gt                   
   ltFFF/gt               lt/DDDgt          lt/XXXgt
            ltCCCgt               ltDDDgt            
          

• ltBBB/gt                    ltBBB/gt                
      ltEEE/gt                    ltFFF/gt            
     lt/DDDgt          lt/CCCgt           ltCCCgt      
           ltBBBgt                    ltBBBgt         
                  ltBBB/gt                    lt/BBBgt
                 lt/BBBgt          lt/CCCgt
       lt/AAAgt

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• Expression in square brackets can further specify
  an element. A number in the brackets gives the
  position of the element in the selected set. The
  function last() selects the last element in the
  selection.   /AAA/BBB1
• Select the first BBB child of element AAA
•      ltAAAgt           ltBBB/gt           ltBBB/gt
            ltBBB/gt           ltBBB/gt      lt/AAAgt

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• /AAA/BBBlast()
• Select the last BBB child of element AAA
•      ltAAAgt           ltBBB/gt           ltBBB/gt
            ltBBB/gt           ltBBB/gt      lt/AAAgt

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• Attributes are specified by _at_ prefix. 
• //_at_id
• Select all attributes _at_id
•      ltAAAgt           ltBBB id "b1"/gt
            ltBBB id "b2"/gt           ltBBB name
  "bbb"/gt           ltBBB/gt      lt/AAAgt

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• //BBB_at_id
• Select BBB elements which have attribute id
•      ltAAAgt           ltBBB id "b1"/gt
            ltBBB id "b2"/gt           ltBBB name
  "bbb"/gt           ltBBB/gt      lt/AAAgt

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• //BBB_at_name
• Select BBB elements which have attribute name
•      ltAAAgt           ltBBB id "b1"/gt
            ltBBB id "b2"/gt           ltBBB name
  "bbb"/gt           ltBBB/gt      lt/AAAgt

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• //BBB_at_
• Select BBB elements which have any attribute
•      ltAAAgt           ltBBB id "b1"/gt
            ltBBB id "b2"/gt           ltBBB name
  "bbb"/gt           ltBBB/gt      lt/AAAgt

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• //BBBnot(_at_)
• Select BBB elements without an attribute
•      ltAAAgt           ltBBB id "b1"/gt
            ltBBB id "b2"/gt           ltBBB name
  "bbb"/gt           ltBBB/gt      lt/AAAgt

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• Values of attributes can be used as selection
  criteria..   //BBB_at_id'b1'
• Select BBB elements which have attribute id with
  value b1
•      ltAAAgt           ltBBB id "b1"/gt
            ltBBB name " bbb "/gt           ltBBB
  name "bbb"/gt      lt/AAAgt

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• //BBB_at_name'bbb'
• Select BBB elements which have attribute name
  with value 'bbb'
•      ltAAAgt           ltBBB id "b1"/gt
            ltBBB name " bbb "/gt           ltBBB
  name "bbb"/gt      lt/AAAgt

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• Normalized-space removes leading and starting
  spaces and replaces sequences of whitespace
  characters by a single space
• //BBBnormalize-space(_at_name)'bbb'
• Select BBB elements which have attribute name
  with value bbb, leading and trailing spaces are
  removed before comparison
•      ltAAAgt           ltBBB id "b1"/gt
            ltBBB name " bbb "/gt           ltBBB
  name "bbb"/gt      lt/AAAgt

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• Function count() counts the number of selected
  elements
•   //count(BBB)2
• Select elements which have two children BBB
•     ltAAAgt           ltCCCgt               ltBBB/gt
                 ltBBB/gt               ltBBB/gt      
      lt/CCCgt           ltDDDgt               ltBBB/gt
                 ltBBB/gt          lt/DDDgt           

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• //count()2
• Select elements which have 2 children
•      ltAAAgt           ltCCCgt               ltBBB/gt
                 ltBBB/gt               ltBBB/gt     
       lt/CCCgt           ltDDDgt               ltBBB/gt
                 ltBBB/gt          lt/DDDgt
            ltEEEgt               ltCCC/gt           
      ltDDD/gt          lt/EEEgt      lt/AAAgt

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• //count()3
• Select elements which have 3 children
•      ltAAAgt           ltCCCgt               ltBBB/gt
                 ltBBB/gt               ltBBB/gt     
       lt/CCCgt           ltDDDgt               ltBBB/gt
                 ltBBB/gt          lt/DDDgt
            ltEEEgt               ltCCC/gt           
      ltDDD/gt          lt/EEEgt      lt/AAAgt

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• //name()'BBB'
• Select all elements with name BBB, equivalent
  with //BBB
•      ltAAAgt           ltBCCgt               ltBBB/gt
                 ltBBB/gt               ltBBB/gt     
       lt/BCCgt           ltDDBgt               ltBBB/gt
                 ltBBB/gt          lt/DDBgt
            

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• //starts-with(name(),'B')
• Select all elements name of which starts with
  letter B
•      ltAAAgt           ltBCCgt               ltBBB/gt
                 ltBBB/gt               ltBBB/gt     
       lt/BCCgt           ltDDBgt               ltBBB/gt
                 ltBBB/gt          lt/DDBgt
            ltBECgt               ltCCC/gt           
      ltDBD/gt          lt/BECgt      lt/AAAgt

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• //contains(name(),'C')
• Select all elements name of which contain letter
  C
•      ltAAAgt           ltBCCgt               ltBBB/gt
                 ltBBB/gt               ltBBB/gt     
       lt/BCCgt           ltDDBgt               ltBBB/gt
                 ltBBB/gt          lt/DDBgt
            ltBECgt               ltCCC/gt           
      ltDBD/gt          lt/BECgt      lt/AAAgt

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• //string-length(name()) 3
• Select elements with three-letter name
•      ltAAAgt           ltQ/gt           ltSSSS/gt
            ltBB/gt           ltCCC/gt
            ltDDDDDDDD/gt           ltEEEE/gt
       lt/AAAgt

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• //string-length(name()) lt 3
• Select elements name of which has one or two
  characters
•      ltAAAgt           ltQ/gt           ltSSSS/gt
            ltBB/gt           ltCCC/gt
            ltDDDDDDDD/gt           ltEEEE/gt
       lt/AAAgt
•  

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• //string-length(name()) gt 3
• Select elements with name longer than three
  characters
•      ltAAAgt           ltQ/gt           ltSSSS/gt
            ltBB/gt           ltCCC/gt
            ltDDDDDDDD/gt           ltEEEE/gt
       lt/AAAgt

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• Several paths can be combined with separator. 
  //CCC //BBB
• Select all elements CCC and BBB
•      ltAAAgt           ltBBB/gt           ltCCC/gt
            ltDDDgt               ltCCC/gt          lt
  /DDDgt           ltEEE/gt      lt/AAAgt

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• /AAA/EEE //BBB
• Select all elements BBB and elements EEE which
  are children of root element AAA
•      ltAAAgt           ltBBB/gt           ltCCC/gt
            ltDDDgt               ltCCC/gt          lt
  /DDDgt           ltEEE/gt      lt/AAAgt

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• /AAA/EEE //DDD/CCC /AAA //BBB
• Number of combinations is not restricted
•      ltAAAgt           ltBBB/gt           ltCCC/gt
            ltDDDgt               ltCCC/gt          lt
  /DDDgt           ltEEE/gt      lt/AAAgt

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• The child axis contains the children of the
  context node. The child axis is the default axis
  and it can be omitted.   /AAA
• Equivalent of /childAAA
•      ltAAAgt           ltBBB/gt           ltCCC/gt
       lt/AAAgt

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• /AAA/BBB
• Equivalent of /childAAA/childBBB
•      ltAAAgt           ltBBB/gt           ltCCC/gt
       lt/AAAgt

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• /childAAA/BBB
• Both possibilities can be combined
•      ltAAAgt           ltBBB/gt           ltCCC/gt
       lt/AAAgt

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• /descendant
• Select all descendats of document root and
  therefore all elements
•      ltAAAgt           ltBBBgt               ltDDDgt
                      ltCCCgt                        
   ltDDD/gt                         ltEEE/gt          
            lt/CCCgt               lt/DDDgt          lt
  /BBBgt           

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• /AAA/BBB/descendant
• Select all descendants of /AAA/BBB
•      ltAAAgt           ltBBBgt               ltDDDgt
                      ltCCCgt                        
   ltDDD/gt                         ltEEE/gt          
            lt/CCCgt               lt/DDDgt          lt
  /BBB

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• //CCC/descendant
• Select all elements which have CCC among its
  ancestors
•      ltAAAgt           ltBBBgt               ltDDDgt
                      ltCCCgt                        
   ltDDD/gt                         ltEEE/gt          
            lt/CCCgt               lt/DDDgt          lt
  /BBBgt           ltCCCgt               

• ltDDDgt        ltEEEgt               ltDDDgt         
                ltFFF/gt                      lt/DDDgt
                      lt/EEEgt               lt/DDDgt 
           lt/CCCgt      lt/AAAgt

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• //CCC/descendantDDD
• Select elements DDD which have CCC among its
  ancestors
•      ltAAAgt           ltBBBgt               ltDDDgt
                      ltCCCgt                        
   ltDDD/gt                         ltEEE/gt          
            lt/CCCgt               lt/DDDgt          lt
  /BBBgt           ltCCCgt               

•          ltDDDgt                    ltEEEgt         
              ltDDDgt                       ltFFF/gt  
                     lt/DDDgt                    lt/EE
  Egt               lt/DDDgt          lt/CCCgt
       lt/AAAgt

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• The parent axis contains the parent of the
  context node, if there is one.   //DDD/parent
• Select all parents of DDD element
•      ltAAAgt           ltBBBgt               ltDDDgt
                      ltCCCgt                        
   ltDDD/gt                         ltEEE/gt          
            lt/CCCgt               lt/DDDgt          lt
  /BBBgt           ltCCCgt               ltDDDgt      
                

• ltEEEgt                       ltDDDgt               
          ltFFF/gt                     lt/DDDgt       
               lt/EEEgt               lt/DDDgt        
    lt/CCCgt      lt/AAAgt