office-gobmx/binaryurp/source/cache.hxx
2011-11-28 22:05:46 +01:00

137 lines
4.2 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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#ifndef INCLUDED_BINARYURP_SOURCE_CACHE_HXX
#define INCLUDED_BINARYURP_SOURCE_CACHE_HXX
#include "sal/config.h"
#include <cassert>
#include <cstddef>
#include <map>
#include "boost/noncopyable.hpp"
#include "sal/types.h"
namespace binaryurp {
namespace cache {
enum { size = 256, ignore = 0xFFFF };
}
template< typename T > class Cache: private boost::noncopyable {
public:
explicit Cache(std::size_t size):
size_(size), first_(map_.end()), last_(map_.end())
{
assert(size < cache::ignore);
}
sal_uInt16 add(T const & content, bool * found) {
assert(found != 0);
typename Map::iterator i(map_.find(content));
*found = i != map_.end();
if (i == map_.end()) {
typename Map::size_type n = map_.size();
if (n < size_) {
i =
(map_.insert(
typename Map::value_type(
content,
Entry(
static_cast< sal_uInt16 >(n), map_.end(),
first_)))).
first;
if (first_ == map_.end()) {
last_ = i;
} else {
first_->second.prev = i;
}
first_ = i;
} else if (last_ != map_.end()) {
i =
(map_.insert(
typename Map::value_type(
content,
Entry(last_->second.index, map_.end(), first_)))).
first;
first_->second.prev = i;
first_ = i;
typename Map::iterator j(last_);
last_ = last_->second.prev;
last_->second.next = map_.end();
map_.erase(j);
} else {
// Reached iff size_ == 0:
return cache::ignore;
}
} else if (i != first_) {
// Move to front (reached only if size_ > 1):
i->second.prev->second.next = i->second.next;
if (i->second.next == map_.end()) {
last_ = i->second.prev;
} else {
i->second.next->second.prev = i->second.prev;
}
i->second.prev = map_.end();
i->second.next = first_;
first_->second.prev = i;
first_ = i;
}
return i->second.index;
}
private:
struct Entry;
typedef std::map< T, Entry > Map;
struct Entry {
sal_uInt16 index;
typename Map::iterator prev;
typename Map::iterator next;
Entry(
sal_uInt16 theIndex, typename Map::iterator thePrev,
typename Map::iterator theNext):
index(theIndex), prev(thePrev), next(theNext) {}
};
std::size_t size_;
Map map_;
typename Map::iterator first_;
typename Map::iterator last_;
};
}
#endif
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