free_form_exp_to_sexp

Converts the free_form_exp to an S-Expression using the S-Expression builders defined in the symbols.

The symbols should have one symbol with an empty string as its name, which is used for words which do not have a symbol name prefix.

The symbols is a NULL-terminated array of known symbols. The NULL should be set for the symbol's name.

Parameters:

free_form_exp	a Free Form Expression
symbols	known symbols, which can be used in the Free From Expression

Returns:

converted free_form_exp into S-Expression, null on error. Free the returned string with a g_free, when done with it.