97 lines
2.5 KiB
C++
97 lines
2.5 KiB
C++
/*
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Copyright (c) 2014 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#include "kernel/type_checker.h"
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#include "library/num.h"
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namespace lean {
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static expr * g_num = nullptr;
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static expr * g_pos_num = nullptr;
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static expr * g_zero = nullptr;
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static expr * g_pos = nullptr;
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static expr * g_one = nullptr;
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static expr * g_bit0 = nullptr;
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static expr * g_bit1 = nullptr;
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void initialize_num() {
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g_num = new expr(Const("num"));
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g_pos_num = new expr(Const("pos_num"));
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g_zero = new expr(Const({"num", "zero"}));
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g_pos = new expr(Const({"num", "pos"}));
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g_one = new expr(Const({"pos_num", "one"}));
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g_bit0 = new expr(Const({"pos_num", "bit0"}));
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g_bit1 = new expr(Const({"pos_num", "bit1"}));
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}
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void finalize_num() {
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delete g_num;
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delete g_pos_num;
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delete g_zero;
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delete g_pos;
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delete g_one;
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delete g_bit0;
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delete g_bit1;
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}
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bool has_num_decls(environment const & env) {
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try {
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type_checker tc(env);
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return
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tc.infer(*g_zero).first == *g_num &&
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tc.infer(*g_pos).first == mk_arrow(*g_pos_num, *g_num) &&
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tc.infer(*g_one).first == *g_pos_num &&
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tc.infer(*g_bit0).first == mk_arrow(*g_pos_num, *g_pos_num) &&
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tc.infer(*g_bit1).first == mk_arrow(*g_pos_num, *g_pos_num);
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} catch (...) {
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return false;
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}
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}
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expr from_pos_num(mpz const & n) {
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lean_assert(n > 0);
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if (n == 1)
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return *g_one;
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if (n % mpz(2) == 1)
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return mk_app(*g_bit1, from_pos_num(n / 2));
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else
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return mk_app(*g_bit0, from_pos_num(n / 2));
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}
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expr from_num(mpz const & n) {
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expr r;
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lean_assert(n >= 0);
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if (n == 0)
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r = *g_zero;
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else
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r = mk_app(*g_pos, from_pos_num(n));
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lean_assert(*to_num(r) == n);
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return r;
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}
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optional<mpz> to_pos_num(expr const & e) {
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if (e == *g_one) {
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return some(mpz(1));
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} else if (is_app(e)) {
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if (app_fn(e) == *g_bit0) {
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if (auto r = to_pos_num(app_arg(e)))
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return some(2*(*r));
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} else if (app_fn(e) == *g_bit1) {
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if (auto r = to_pos_num(app_arg(e)))
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return some(2*(*r) + 1);
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}
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}
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return optional<mpz>();
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}
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optional<mpz> to_num(expr const & e) {
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if (e == *g_zero)
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return some(mpz(0));
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else if (is_app(e) && app_fn(e) == *g_pos)
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return to_pos_num(app_arg(e));
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else
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return optional<mpz>();
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}
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}
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