82 lines
2.1 KiB
C++
82 lines
2.1 KiB
C++
|
/*
|
||
|
|
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 "kernel/type_checker.h"
|
||
|
|
#include "library/num.h"
|
||
|
|
|
||
|
|
namespace lean {
|
||
|
|
static expr g_num(Const({"num", "num"}));
|
||
|
|
static expr g_pos_num(Const({"num", "pos_num"}));
|
||
|
|
static expr g_zero(Const({"num", "zero"}));
|
||
|
|
static expr g_pos(Const({"num", "pos"}));
|
||
|
|
static expr g_one(Const({"num", "one"}));
|
||
|
|
static expr g_bit0(Const({"num", "bit0"}));
|
||
|
|
static expr g_bit1(Const({"num", "bit1"}));
|
||
|
|
|
||
|
|
bool has_num_decls(environment const & env) {
|
||
|
|
try {
|
||
|
|
type_checker tc(env);
|
||
|
|
return
|
||
|
|
tc.infer(g_zero) == g_num &&
|
||
|
|
tc.infer(g_pos) == mk_arrow(g_pos_num, g_num) &&
|
||
|
|
tc.infer(g_one) == g_pos_num &&
|
||
|
|
tc.infer(g_bit0) == mk_arrow(g_pos_num, g_pos_num) &&
|
||
|
|
tc.infer(g_bit1) == mk_arrow(g_pos_num, g_pos_num);
|
||
|
|
} catch (...) {
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
expr from_pos_num(mpz const & n) {
|
||
|
|
lean_assert(n > 0);
|
||
|
|
if (n == 1)
|
||
|
|
return g_one;
|
||
|
|
if (n % mpz(2) == 1)
|
||
|
|
return mk_app(g_bit1, from_pos_num(n / 2));
|
||
|
|
else
|
||
|
|
return mk_app(g_bit0, from_pos_num(n / 2));
|
||
|
|
}
|
||
|
|
|
||
|
|
expr from_num(mpz const & n) {
|
||
|
|
expr r;
|
||
|
|
lean_assert(n >= 0);
|
||
|
|
if (n == 0)
|
||
|
|
r = g_zero;
|
||
|
|
else
|
||
|
|
r = mk_app(g_pos, from_pos_num(n));
|
||
|
|
lean_assert(*to_num(r) == n);
|
||
|
|
return r;
|
||
|
|
}
|
||
|
|
|
||
|
|
mpz to_pos_num_core(expr const & e) {
|
||
|
|
if (e == g_one)
|
||
|
|
return mpz(1);
|
||
|
|
else if (app_fn(e) == g_bit0)
|
||
|
|
return 2 * to_pos_num_core(app_arg(e));
|
||
|
|
else if (app_fn(e) == g_bit1)
|
||
|
|
return 2 * to_pos_num_core(app_arg(e)) + 1;
|
||
|
|
else
|
||
|
|
throw exception("expression does not represent a numeral");
|
||
|
|
}
|
||
|
|
|
||
|
|
mpz to_num_core(expr const & e) {
|
||
|
|
if (e == g_zero)
|
||
|
|
return mpz(0);
|
||
|
|
else if (app_fn(e) == g_pos)
|
||
|
|
return to_pos_num_core(app_arg(e));
|
||
|
|
else
|
||
|
|
throw exception("expression does not represent a numeral");
|
||
|
|
}
|
||
|
|
|
||
|
|
optional<mpz> to_num(expr const & e) {
|
||
|
|
try {
|
||
|
|
return optional<mpz>(to_num_core(e));
|
||
|
|
} catch (...) {
|
||
|
|
return optional<mpz>();
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|