Generating C++ code

[Ulrich Eckhardt]

Am 09.10.2012 18:00, schrieb Jean-Michel Pichavant:
> I'm trying to generate C++ code from an XML file. I'd like to use a
> template engine, which imo produce something readable and
> maintainable.
> [...]
> Here's my flow:
>
> XML file -> nice python app -> C++ code

There is one question that you should answer (or maybe decide?) first: 
How close is the XML structure to C++ semantically?

The syntactic level is obviously very different, as one uses XML as 
metaformat while the other is C++. The semantic level is rather about 
the question if there is e.g. a "<class name='foo'>" that directly 
translates to a "class foo {" in C++. If that is the case, the SAX API 
should help you, as it basically invokes callbacks for every XML element 
encountered while parsing the input stream. In those callbacks, you 
could then generate the according C++ code in a way that should be 
readable and maintainable with plain Python or some template engine.

You you need to skip back-and-forth over the input, reading the whole 
XML as DOM tree would probably be a better approach. Still, the 
processing of input is separate from output generation, so you could at 
least divide your task before conquering it.

Notes:
  - There is also XSLT which can generate pretty much anything from XML, 
but it is can't do much more than text replacements triggered by input 
matching. The more the output differs semantically from the input, the 
more difficult it becomes to use. Also, XSLT tends to become write-only 
code, i.e. unreadable.
  - I think there was a feature in GCC that allows generating XML from 
C++ input, maybe even the reverse. Maybe you could leverage that?


Good luck!

Uli