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#ifndef INTERN_POOL_H
#define INTERN_POOL_H
#define DEBUG_INTERN_POOL(x) x
/* to "intern" a string in lisp is to make a symbol from it (a pointer to a canonical copy whose pointer can be equality-compared/hashed directly with other interned things). we take an Item that has a key part and some mutable parts (that aren't in its identity), and we hash-by-value the key part to map to a canonical on-heap Item - and we use a boost object pool to allocate them */
//FIXME: actually store function object state (assumed stateless so far)
#include <boost/pool/object_pool.hpp>
#include "hash.h"
//#include "null_traits.h"
#include <functional>
template <class I>
struct get_key { // default accessor for I = like pair<key,val>
typedef typename I::first_type const& result_type;
typedef I const& argument_type;
result_type operator()(I const& i) const {
return i.first;
}
};
// Arg type should be the non-pointer version. this saves me from using boost type traits to remove_pointer. f may be binary or unary
template <class KeyF,class F,class Arg=typename KeyF::argument_type>
struct compose_indirect {
typedef Arg *argument_type; // we also accept Arg &
KeyF kf;
F f;
typedef typename F::result_type result_type;
result_type operator()(Arg const& p) const {
return f(kf(p));
}
result_type operator()(Arg & p) const {
return f(kf(p));
}
result_type operator()(Arg * p) const {
return f(kf(*p));
}
template <class V>
result_type operator()(V const& v) const {
return f(kf(*v));
}
result_type operator()(Arg const& a1,Arg const& a2) const {
return f(kf(a1),kf(a2));
}
result_type operator()(Arg & a1,Arg & a2) const {
return f(kf(a1),kf(a2));
}
result_type operator()(Arg * a1,Arg * a2) const {
return f(kf(*a1),kf(*a2));
}
template <class V,class W>
result_type operator()(V const& v,W const&w) const {
return f(kf(*v),kf(*w));
}
};
/*
template <class F>
struct indirect_function {
F f;
explicit indirect_function(F const& f=F()) : f(f) {}
typedef typename F::result_type result_type;
template <class V>
result_type operator()(V *p) const {
return f(*p);
}
};
*/
template <class Item,class KeyF=get_key<Item>,class HashKey=boost::hash<typename KeyF::result_type>,class EqKey=std::equal_to<typename KeyF::result_type>, class Pool=boost::object_pool<Item> >
struct intern_pool : Pool {
KeyF key;
typedef typename KeyF::result_type Key;
typedef Item *Handle;
typedef compose_indirect<KeyF,HashKey,Item> HashDeep;
typedef compose_indirect<KeyF,EqKey,Item> EqDeep;
typedef HASH_SET<Handle,HashDeep,EqDeep> Canonical;
typedef typename Canonical::iterator CFind;
typedef std::pair<CFind,bool> CInsert;
Canonical canonical;
bool interneq(Handle &i) { // returns true if i is newly interned, false if it already existed
CInsert i_new=canonical.insert(i);
i=*i_new.first;
return i_new.second;
}
// inherited: Handle construct(...)
Handle construct_fresh() { return Pool::construct(); }
Handle intern(Handle i) { // (maybe invalidating i, returning a valid canonical handle (pointer)
CInsert i_new=canonical.insert(i);
if (i_new.second)
return i;
else {
free(i);
return *i_new->first;
}
}
void destroy_interned(Handle i) {
DEBUG_INTERN_POOL(assert(canonical.find(i)!=canonical.end()));
canonical.erase(i);
destroy(i);
}
bool destroy_fresh(Handle i) {
DEBUG_INTERN_POOL(assert(canonical.find(i)!=canonical.end()||*canonical.find(i)!=i)); // i is a constructed item not yet interned.
destroy(i);
}
void destroy_both(Handle i) { // i must have come from this pool. may be interned, or not. destroy both the noninterned and interned.
if (!destroy_if_interned(i)) destroy(i);
}
// destroy intern(i) if it exists. return true if it existed AND its address was i. otherwise return false (whether or not a value-equal item existed and was destroyed)
bool destroy_if_interned(Handle i) {
CFind f=canonical.find(i);
if (f!=canonical.end()) {
Handle interned=*f;
canonical.erase(f);
destroy(f);
if (f==i) return true;
}
return false;
}
intern_pool() {
HASH_MAP_EMPTY(canonical,(Handle)0);
}
};
#endif
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