Angus Leeming wrote:
Gennadiy Rozental wrote:
You need to implement iterator that match InputIterator concept. Also it is very similar to iteration though N-ary matrix.
You need to build a collection of directory iterators on each level.
Here is a sketch of how next function would look like (if you use input_iterator_adaptor).
void next() { starting from end find first level iterator that is not equal to end
If not found, finite la comedi.
if found last level, increment it and that's all
If found level in the middle increment it, rebuild all directory iterators for following levels and start from the beginning. }
I think there should be iterator like this (generic, over matrix) somewhere.If not it would be interesting undertaking.
Gennadiy,
Thank you for this. I'll mull it over and get back to you.
Ok, I've thought a bit and think I understand your proposal. Let's use a class to store the predicates that will be used to initialise the filter_iterators at each level of the tree: class glob_pattern { vector<glob_predicate<> > predicates; }; Ie, "../foo*bar/baz?.eps" would require that glob_pattern stored a vector of 3 predicates. Let's call these "filter_iterators at each level of the tree" glob_directory_iterators. A glob_iterator will store a vector of glob_directory_iterators. (Also 3 in the example's case). Incrementing a glob_iterator will use a strategy similar to the one you outline above. class glob_pattern { vector<glob_predicate<> > predicates; public: glob_iterator begin() const; glob_iterator end() const; }; class glob_iterator { vector<glob_directory_iterator> dir_iterators; public: glob_iterator(vector<glob_predicate<> > const & p) { typedef vector<glob_predicate<> > p_vec; dir_iterators.reserve(p.size()); p_vec::const_iterator it = p.begin(); p_vec::const_iterator const end = p.end(); for (; it != end; ++it) dir_iterators.push_back( glob_directory_iterator(*it)); } glob_iterator operator++() { /* implement the "next" strategy */ } }; This strategy moves all the nonsense about "does the predicate contain wildcards or not" into glob_directory_iterator. Fine. No doubt there's lots of implementation details left, (like using input_iterator_adaptor), but I think that this pseudo code covers the idea. Am I on the right track? Angus