82 lines
2.5 KiB
C++
82 lines
2.5 KiB
C++
/*
|
|
Copyright (c) 2013 Microsoft Corporation. All rights reserved.
|
|
Released under Apache 2.0 license as described in the file LICENSE.
|
|
|
|
Author: Leonardo de Moura
|
|
*/
|
|
#include <unordered_set>
|
|
#include "util/buffer.h"
|
|
#include "library/max_sharing.h"
|
|
|
|
namespace lean {
|
|
/**
|
|
\brief Implementation of the functional object for creating expressions with maximally
|
|
shared sub-expressions.
|
|
*/
|
|
struct max_sharing_fn::imp {
|
|
struct expr_struct_eq { unsigned operator()(expr const & e1, expr const & e2) const { return e1 == e2; }};
|
|
typedef typename std::unordered_set<expr, expr_hash, expr_struct_eq> expr_cache;
|
|
|
|
expr_cache m_cache;
|
|
|
|
void cache(expr const & a) {
|
|
a.raw()->set_max_shared();
|
|
m_cache.insert(a);
|
|
}
|
|
|
|
expr apply(expr const & a) {
|
|
auto r = m_cache.find(a);
|
|
if (r != m_cache.end()) {
|
|
lean_assert((*r).raw()->max_shared());
|
|
return *r;
|
|
}
|
|
if (a.raw()->max_shared()) {
|
|
m_cache.insert(a);
|
|
return a;
|
|
}
|
|
switch (a.kind()) {
|
|
case expr_kind::Var: case expr_kind::Constant: case expr_kind::Type: case expr_kind::Value:
|
|
cache(a);
|
|
return a;
|
|
case expr_kind::App: {
|
|
expr r = update_app(a, [=](expr const & c){ return apply(c); });
|
|
cache(r);
|
|
return r;
|
|
}
|
|
case expr_kind::Eq : {
|
|
expr r = update_eq(a, [=](expr const & l, expr const & r){ return std::make_pair(apply(l), apply(r)); });
|
|
cache(r);
|
|
return r;
|
|
}
|
|
case expr_kind::Lambda:
|
|
case expr_kind::Pi: {
|
|
expr r = update_abst(a, [=](expr const & t, expr const & b) { return std::make_pair(apply(t), apply(b)); });
|
|
cache(r);
|
|
return r;
|
|
}
|
|
case expr_kind::Let: {
|
|
expr r = update_let(a, [=](expr const & t, expr const & v, expr const & b) {
|
|
expr new_t = t ? apply(t) : expr();
|
|
return std::make_tuple(new_t, apply(v), apply(b));
|
|
});
|
|
cache(r);
|
|
return r;
|
|
}}
|
|
lean_unreachable();
|
|
return a;
|
|
}
|
|
expr operator()(expr const & a) { return apply(a); }
|
|
};
|
|
|
|
max_sharing_fn::max_sharing_fn():m_imp(new imp) {}
|
|
max_sharing_fn::~max_sharing_fn() {}
|
|
expr max_sharing_fn::operator()(expr const & a) { return (*m_imp)(a); }
|
|
void max_sharing_fn::clear() { m_imp->m_cache.clear(); }
|
|
|
|
expr max_sharing(expr const & a) {
|
|
if (a.raw()->max_shared())
|
|
return a;
|
|
else
|
|
return max_sharing_fn::imp()(a);
|
|
}
|
|
} // namespace lean
|