NAME

       stag-diff - finds the difference between two stag files

SYNOPSIS

         stag-diff -ignore foo-id -ignore bar-id file1.xml file2.xml

DESCRIPTION

       Compares two data trees and reports whether they match. If they do not match, the mismatch
       is reported.

   ARGUMENTS
       -help|h
           shows this document

       -ignore|i ELEMENT
           these nodes are ignored for the purposes of comparison. Note that attributes are
           treated as elements, prefixed by the containing element id. For example, if you have

             <foo ID="wibble">

           And you wish to ignore the ID attribute, then you would use the switch

             -ignore foo-ID

           You can specify multiple elements to ignore like this

             -i foo -i bar -i baz

           You can also specify paths

             -i foo/bar/bar-id

       -parser|p FORMAT
           which parser to use. The default is XML. This can also be autodetected by the file
           suffix. Other alternatives are sxpr and itext. See Data::Stag for details.

       -report|r ELEMENT
           report mismatches as they occur on each element of type ELEMENT

           multiple elements can be specified

       -verbose|v
           used in conjunction with the -report switch

           shows the tree of the mismatching element

   OUTPUT
       If a mismatch is reported, a report is generated displaying the subpart of the tree that
       could not be matched. This will look like this:

       REASON: no_matching_node: annotation
         no_matching_node: feature_set
           no_matching_node: feature_span
             no_matching_node: evidence
               no_matching_node: evidence-id
                 data_mismatch(:15077290 ne :15077291): evidence-id AND evidence-id

       Due to the nature of tree matching, it can be difficult to specify exactly how trees do
       not match. To investigate this, you may need to use the -r and -v options. For the above
       output, I would recommend using

         stag-diff -r feature_span -v

   ALGORITHM
       Both trees are recursively traversed... see the actual code for how this works

       The order of elements is not important; eg

         <foo>
           <bar>
             <baz>1</baz>
           </bar>
           <bar>
             <baz>2</baz>
           </bar>
         </foo>

       matches

         <foo>
           <bar>
             <baz>2</baz>
           </bar>
           <bar>
             <baz>1</baz>
           </bar>
         </foo>

       The recursive nature of this algorithm means that certain tree comparisons will explode
       wrt time and memory. I think this will only happen with very deep trees where nodes high
       up in the tree can only be differentiated by nodes low down in the tree.

       Both trees are loaded into memory to begin with, so it may thrash with very large
       documents

   AUTHOR
       Chris Mungall cjm at fruitfly dot org

SEE ALSO

       Data::Stag