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perf(library/num): avoid exception

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2014-08-14 09:08:39 -07:00
parent 19537b72ee
commit ebbca0d613
1 changed files with 16 additions and 22 deletions
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36
src/library/num.cpp
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@ -51,31 +51,25 @@ expr from_num(mpz const & 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");
optional<mpz> to_pos_num(expr const & e) {
if (e == g_one) {
return some(mpz(1));
} else if (app_fn(e) == g_bit0) {
if (auto r = to_pos_num(app_arg(e)))
return some(2*(*r));
} else if (app_fn(e) == g_bit1) {
if (auto r = to_pos_num(app_arg(e)))
return some(2*(*r) + 1);
}
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");
return optional<mpz>();
}
optional<mpz> to_num(expr const & e) {
try {
return optional<mpz>(to_num_core(e));
} catch (...) {
if (e == g_zero)
return some(mpz(0));
else if (is_app(e) && app_fn(e) == g_pos)
return to_pos_num(app_arg(e));
else
return optional<mpz>();
}
}
}