lib/sax/helpers/sax_locator_impl.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 #
   3 # This file is free software, which comes along with NIT. This software is
   4 # distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
   5 # without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
   6 # PARTICULAR PURPOSE. You can modify it is you want, provided this header
   7 # is kept unaltered, and a notification of the changes is added.
   8 # You are allowed to redistribute it and sell it, alone or is a part of
   9 # another product.
  10
  11 # Provides an optional convenience implementation of `Locator`.
  12 module sax::helpers::sax_locator_impl
  13
  14 import sax::sax_locator
  15
  16 # Provides an optional convenience implementation of `Locator`.
  17 #
  18 # This class is available mainly for application writers, who
  19 # can use it to make a persistent snapshot of a locator at any
  20 # point during a document parse:
  21 #
  22 #     import sax::helpers::sax_locator_impl
  23 #     import sax::content_handler
  24 #
  25 #     class Example super ContentHandler
  26 #       private var locator: SAXLocator
  27 #       private var start_loc: nullable SAXLocator = null
  28 #
  29 #       redef fun start_document do
  30 #               # save the location of the start of the document
  31 #               # for future use.
  32 #               start_loc = new SAXLocatorImpl.with(locator)
  33 #       end
  34 #     end
  35 #
  36 # Normally, parser writers will not use this class, since it
  37 # is more efficient to provide location information only when
  38 # requested, rather than constantly updating a `Locator` object.
  39 #
  40 # Note: The original source code and documentation of this class comes, in part,
  41 # from [SAX 2.0](http://www.saxproject.org).
  42 class SAXLocatorImpl super SAXLocator
  43         redef var public_id: nullable String = null is writable
  44         redef var system_id: nullable String = null is writable
  45         redef var line_number: Int = -1 is writable
  46         redef var column_number: Int = -1 is writable
  47
  48         # Zero-argument constructor.
  49         #
  50         # This will not normally be useful, since the main purpose
  51         # of this class is to make a snapshot of an existing Locator.
  52         init do
  53         end
  54
  55         # Copy constructor.
  56         #
  57         # Create a persistent copy of the current state of a locator.
  58         # When the original locator changes, this copy will still keep
  59         # the original values (and it can be used outside the scope of
  60         # `ContentHandler` methods).
  61         #
  62         # Parameters:
  63         #
  64         # * `locator`: locator to copy.
  65         init with(locator: SAXLocator) do
  66                 public_id = locator.public_id
  67                 system_id = locator.system_id
  68                 line_number = locator.line_number
  69                 column_number = locator.column_number
  70         end
  71 end