Re: [Boost-bugs] [Boost C++ Libraries] #11600: boost property_tree exponential newline growth

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #11600: boost property_tree exponential newline growth
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2016-02-11 09:51:54

#11600: boost property_tree exponential newline growth
------------------------------------------+---------------------------
  Reporter:  Timo Strunk <Timo.Strunk@…>  |      Owner:  cornedbee
      Type:  Bugs                         |     Status:  closed
 Milestone:  To Be Determined             |  Component:  property_tree
   Version:  Boost 1.59.0                 |   Severity:  Problem
Resolution:  invalid                      |   Keywords:
------------------------------------------+---------------------------

Comment (by Timo Strunk <timo.strunk@…>):

 Without my code you currently cannot round-trip the following XML using
 Property Tree:

     <XML>
          <Text>AB  CD</Text>
     </XML>

 There are two protected spaces in between AB and CD. I need those two
 spaces.

 Using the previous boost 1.59 code you end up with:

     <?xml version="1.0" encoding="utf-8"?>
     <XML>
       &#10;  &#10;  &#10;    &#10;&#10;  &#10;&#10;  &#10;
       <Text>AB  CD</Text>
     </XML>

 This is good, because the text is not broken, but if the XML is rewritten
 several million times you end up with a GB of '&#10;' (or actual newlines
 in case of pull request #18).

 Using trim_whitespace you end up with:
     <?xml version="1.0" encoding="utf-8"?>
     <XML>
       <Text>AB CD</Text>
     </XML>

 which makes everything look nice, but the double whitespace in the middle
 is gone.

 The problem here is that property_tree::trim_whitespace is converted to
 rapidxml::normalize_whitespace. The trim_whitespace option of rapidxml is
 not exposed.

 My change (incorrectly, you are right) trims whitespace, even if
 trim_whitespace is not enabled.
 Therefore my suggestion would be: I send a third Pull request in which I
 integrate a new option
 boost::property_tree::xml_parser::trim_but_dont_normalize_whitespace,
 which enables rapidxml::trim_whitespace but not
 rapidxml::normalize_whitespace.

 Would this be acceptable for you?

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11600#comment:5>
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