thin-provisioning-tools/persistent-data/space-maps/subtracting_span_iterator.h

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#ifndef SPAN_ITERATOR_H
#define SPAN_ITERATOR_H
#include "persistent-data/space_map.h"
#include <set>
//----------------------------------------------------------------
namespace persistent_data {
// FIXME: rewrite with tests using the run_list stuff.
class subtracting_span_iterator : public space_map::span_iterator {
public:
typedef set<block_address> block_set;
typedef space_map::span span;
subtracting_span_iterator(span_iterator &sub_it,
block_set const &forbidden_blocks)
: sub_it_(sub_it),
forbidden_blocks_(forbidden_blocks),
current_begin_() {
}
virtual maybe_span first() {
current_span_ = sub_it_.first();
if (current_span_)
current_begin_ = current_span_->first;
return next();
}
virtual maybe_span next() {
maybe_span r;
while (more_spans()) {
r = next_();
if (r)
break;
}
return r;
}
private:
bool more_spans() const {
return current_span_;
}
bool span_consumed() const {
return current_begin_ == current_span_->second;
}
bool forbidden_block(block_address b) const {
return forbidden_blocks_.count(b) > 0;
}
void skip_forbidden_blocks() {
while (!span_consumed() && forbidden_block(current_begin_))
current_begin_++;
}
span get_span() {
block_address b = current_begin_;
while (!span_consumed() && !forbidden_block(current_begin_))
current_begin_++;
return span(b, current_begin_);
}
void get_current_span_from_sub_it() {
current_span_ = sub_it_.next();
if (current_span_)
current_begin_ = current_span_->first;
}
maybe_span next_() {
if (span_consumed())
get_current_span_from_sub_it();
if (!more_spans())
return maybe_span();
skip_forbidden_blocks();
if (!span_consumed())
return maybe_span(get_span());
else
return maybe_span();
}
span_iterator &sub_it_;
block_set const &forbidden_blocks_;
maybe_span current_span_;
block_address current_begin_;
};
}
//----------------------------------------------------------------
#endif