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 #     module example
  23 #     #
  24 #     import sax::helpers::SAXLocatorImpl
  25 #     import sax::ContentHandler
  26 #     #
  27 #     class Example super ContentHandler
  28 #       private var _locator: nullable SAXLocator = null
  29 #       private var start_loc: nullable SAXLocator = null
  30 #     #
  31 #       fun locator=(Locator locator) do
  32 #               # note the locator
  33 #               _locator = locator
  34 #       end
  35 #     #
  36 #       fun start_document do
  37 #               # save the location of the start of the document
  38 #               # for future use.
  39 #               start_loc = new SAXLocatorImpl.from(locator)
  40 #       end
  41 #     end
  42 #
  43 # Normally, parser writers will not use this class, since it
  44 # is more efficient to provide location information only when
  45 # requested, rather than constantly updating a `Locator` object.
  46 #
  47 # Note: The original source code and documentation of this class comes, in part,
  48 # from [SAX 2.0](http://www.saxproject.org).
  49 class SAXLocatorImpl super SAXLocator
  50         redef var public_id: nullable String = null is writable
  51         redef var system_id: nullable String = null is writable
  52         redef var line_number: Int = -1 is writable
  53         redef var column_number: Int = -1 is writable
  54
  55         # Zero-argument constructor.
  56         #
  57         # This will not normally be useful, since the main purpose
  58         # of this class is to make a snapshot of an existing Locator.
  59         init do
  60         end
  61
  62         # Copy constructor.
  63         #
  64         # Create a persistent copy of the current state of a locator.
  65         # When the original locator changes, this copy will still keep
  66         # the original values (and it can be used outside the scope of
  67         # `ContentHandler` methods).
  68         #
  69         # Parameters:
  70         #
  71         # * `locator`: locator to copy.
  72         init with(locator: SAXLocator) do
  73                 public_id = locator.public_id
  74                 system_id = locator.system_id
  75                 line_number = locator.line_number
  76                 column_number = locator.column_number
  77         end
  78 end