lean2/src/kernel/expr_eq_fn.cpp

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/*
Copyright (c) 2014 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
*/
#include <vector>
#include <memory>
#include "util/interrupt.h"
#include "util/thread.h"
#include "kernel/expr.h"
#include "kernel/expr_sets.h"
#ifndef LEAN_EQ_CACHE_CAPACITY
#define LEAN_EQ_CACHE_CAPACITY 1024*8
#endif
namespace lean {
struct eq_cache {
struct entry {
expr_ptr m_a;
expr_ptr m_b;
entry():m_a(nullptr), m_b(nullptr) {}
};
unsigned m_capacity;
std::vector<entry> m_cache;
std::vector<unsigned> m_used;
eq_cache():m_capacity(LEAN_EQ_CACHE_CAPACITY), m_cache(LEAN_EQ_CACHE_CAPACITY) {}
bool check(expr const & a, expr const & b) {
unsigned i = hash(a.hash_alloc(), b.hash_alloc()) % m_capacity;
if (m_cache[i].m_a == a.raw() && m_cache[i].m_b == b.raw()) {
return true;
} else {
if (m_cache[i].m_a == nullptr)
m_used.push_back(i);
m_cache[i].m_a = a.raw();
m_cache[i].m_b = b.raw();
return false;
}
}
void clear() {
for (unsigned i : m_used)
m_cache[i].m_a = nullptr;
m_used.clear();
}
};
MK_THREAD_LOCAL_GET_DEF(eq_cache, get_eq_cache);
/** \brief Functional object for comparing expressions.
Remark if CompareBinderInfo is true, then functional object will also compare
binder information attached to lambda and Pi expressions */
template<bool CompareBinderInfo>
class expr_eq_fn {
eq_cache & m_cache;
bool apply(expr const & a, expr const & b) {
if (is_eqp(a, b)) return true;
if (a.hash() != b.hash()) return false;
if (a.kind() != b.kind()) return false;
if (is_var(a)) return var_idx(a) == var_idx(b);
if (m_cache.check(a, b))
return true;
check_system("expression equality test");
switch (a.kind()) {
case expr_kind::Var:
lean_unreachable(); // LCOV_EXCL_LINE
case expr_kind::Constant:
return
const_name(a) == const_name(b) &&
compare(const_levels(a), const_levels(b), [](level const & l1, level const & l2) { return l1 == l2; });
case expr_kind::Meta:
return
mlocal_name(a) == mlocal_name(b) &&
apply(mlocal_type(a), mlocal_type(b));
case expr_kind::Local:
return
mlocal_name(a) == mlocal_name(b) &&
apply(mlocal_type(a), mlocal_type(b)) &&
(!CompareBinderInfo || local_pp_name(a) == local_pp_name(b)) &&
(!CompareBinderInfo || local_info(a) == local_info(b));
case expr_kind::App:
return
apply(app_fn(a), app_fn(b)) &&
apply(app_arg(a), app_arg(b));
case expr_kind::Lambda: case expr_kind::Pi:
return
apply(binding_domain(a), binding_domain(b)) &&
apply(binding_body(a), binding_body(b)) &&
(!CompareBinderInfo || binding_info(a) == binding_info(b));
case expr_kind::Sort:
return sort_level(a) == sort_level(b);
case expr_kind::Macro:
if (macro_def(a) != macro_def(b) || macro_num_args(a) != macro_num_args(b))
return false;
for (unsigned i = 0; i < macro_num_args(a); i++) {
if (!apply(macro_arg(a, i), macro_arg(b, i)))
return false;
}
return true;
}
lean_unreachable(); // LCOV_EXCL_LINE
}
public:
expr_eq_fn():m_cache(get_eq_cache()) {}
~expr_eq_fn() { m_cache.clear(); }
bool operator()(expr const & a, expr const & b) { return apply(a, b); }
};
bool is_equal(expr const & a, expr const & b) {
return expr_eq_fn<false>()(a, b);
}
bool is_bi_equal(expr const & a, expr const & b) {
return expr_eq_fn<true>()(a, b);
}
}