I use boost property tree to write some nice xml files and everything works fine... but I would like to somehow make sure that one specific block is at the start of the xml file. This block is a general block about the software and some general settings and it would be great for human readers that this block is at the beginning. Unfortunately I cannot make sure that this block is always the first that is written... Is there another easy solution or workaround?
Just use insert:
ptree pt;
pt.add("a.c.d", "hello");
pt.add("a.e", "world");
pt.add("a.b", "bye");
write_xml(std::cout, pt, boost::property_tree::xml_writer_make_settings<std::string>(' ', 2));
Prints
<?xml version="1.0" encoding="utf-8"?>
<a>
<c>
<d>hello</d>
</c>
<e>world</e>
<b>bye</b>
</a>
Using insert to insert a node at a specific location:
// let's move `b` to the start:
ptree pt;
pt.add("a.c.d", "hello");
pt.add("a.e", "world");
auto& a = pt.get_child("a");
a.insert(a.begin(), {"b", ptree{"bye"}});
write_xml(std::cout, pt, boost::property_tree::xml_writer_make_settings<std::string>(' ', 2));
Prints
<?xml version="1.0" encoding="utf-8"?>
<a>
<b>bye</b>
<c>
<d>hello</d>
</c>
<e>world</e>
</a>