Stefan,
I'm using boost::wave to implement a C/C++ preprocessor for the Synopsis (http://synopsis.fresco.org/) project. I have just been asked for support of the '-include' command line option, which, for typical compilers, means to preload an include file before parsing the actual input.
I wonder how to implement that with wave. The wave::context<> constructor expects two input iterators (begin and end) which it will use during parsing. Relying only on this would mean I have to write my own iterators (or wrapper container) that is able to switch from one input source (the one specified by '-include') to the next (the actual input file).
However, I believe there is a lot of value in wave::context<> being able to do that internally (either, by allowing to reassign a new pair of iterators, or by providing a copy constructor for the context that creates a new context from a new pair of iterators, but inherits the state of an existing context).
Does anything like this exist ? Are there plans to support such use cases ?
Wave does already support that! The iterator returned from the context has a member function force_include(): context_type::iterator_type it = ctx.begin(); for (each of the files to be pre-included) it.force_include(filename, last_name); Note, you have to call force_include() in reverse order if compared to the sequence of files to pre-include, i.e. the file to be pre-included first has to be supplied to force_include() last. The additional flag (second parameter) has to be true when calling force_include() for the last time (for the 'first' file). Obviously you need to call force_include() _before_ you dereference the iterator for the first time. BTW, if you would like to see an example how to implement this, the wave driver applet has a command line option --forceinclude/-F allowing to specify one or several files to be pre-included before the actual preprocessing begins: vector<string>::const_reverse_iterator rend = force.rend(); for (vector<string>::const_reverse_iterator cit = force.rbegin(); cit != rend; /**/) { string filename(*cit); first.force_include(filename.c_str(), ++cit == rend); } where 'force' is a vector containing the filenames to pre-include and 'first' is the iterator returned from ctx.begin(). HTH Regards Hartmut