lean2/src/kernel/max_sharing.cpp

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/*
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 "buffer.h"
#include "max_sharing.h"
namespace lean {
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 & v, expr const & b) { return std::make_pair(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