Re: [Help-glpk] MathProg Parser

[Andrew Makhorin]

> I am currently trying to find a way to retrieve the symbols
> through the API, and to retrieve data using the symbols.
>>From previous posts, I understand that I cannot get the marginal
>>value of a constraint from the mathprog language, I have to go
>>through the API.
> So, to summarize the problem, if i cannot do API stuff from
> mathprog then i need to do mathprog stuff from the API.

In principle, there should be a feature in the language to obtain
additional solution components like reduced costs, the solution
status, etc. However, this is not implemented yet.

> I found the MPL struct that seems to contains all I need but it
> is destroyed at the end of the loadmodel api. The first patch would
> be to make it persistant.

lpx_read_model is a simplified driver to the mathprog translator.
See comments to the translator api routines in file 'glpmpl04.c'
(mpl_initialize, mpl_read_model, etc.).

> Is there any work planned on this part?
> Has anybody already done something in this way?
> This way sounds quite difficult, it might be easier to add some
> keywords to mathprog. The mathprog parser looks quite complicated,
> has it been built with yacc/lex tools or by hand?
> Is there the grammar source code somewhere?

The mathprog parser is based on the recursive descent. It was written
in a direct way without using automated tools like yacc and lex.