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import std._uint;
import std._int;
import std._vec;
// FIXME: With recursive object types, we could implement binary methods like
// union, intersection, and difference. At that point, we could write
// an optimizing version of this module that produces a different obj
// for the case where nbits <= 32.
// FIXME: Almost all the functions in this module should be state fns, but the
// effect system isn't currently working correctly.
state type t = rec(vec[mutable uint] storage, uint nbits);
// FIXME: this should be a constant once they work
fn uint_bits() -> uint {
ret 32u + ((1u << 32u) >> 27u);
}
fn create(uint nbits, bool init) -> t {
auto elt;
if (init) {
elt = ~0u;
} else {
elt = 0u;
}
auto storage = _vec.init_elt[mutable uint](elt, nbits / uint_bits() + 1u);
ret rec(storage = storage, nbits = nbits);
}
impure fn process(&fn(uint, uint) -> uint op, &t v0, &t v1) -> bool {
auto len = _vec.len[mutable uint](v1.storage);
check (_vec.len[mutable uint](v0.storage) == len);
check (v0.nbits == v1.nbits);
auto changed = false;
for each (uint i in _uint.range(0u, len)) {
auto w0 = v0.storage.(i);
auto w1 = v1.storage.(i);
auto w = op(w0, w1);
if (w0 != w) {
changed = true;
v0.storage.(i) = w;
}
}
ret changed;
}
fn lor(uint w0, uint w1) -> uint {
ret w0 | w1;
}
impure fn union(&t v0, &t v1) -> bool {
auto sub = lor;
ret process(sub, v0, v1);
}
fn land(uint w0, uint w1) -> uint {
ret w0 & w1;
}
impure fn intersect(&t v0, &t v1) -> bool {
auto sub = land;
ret process(sub, v0, v1);
}
fn right(uint w0, uint w1) -> uint {
ret w1;
}
impure fn copy(&t v0, t v1) -> bool {
auto sub = right;
ret process(sub, v0, v1);
}
fn get(&t v, uint i) -> bool {
check (i < v.nbits);
auto bits = uint_bits();
auto w = i / bits;
auto b = i % bits;
auto x = 1u & (v.storage.(w) >> b);
ret x == 1u;
}
fn equal(&t v0, &t v1) -> bool {
// FIXME: when we can break or return from inside an iterator loop,
// we can eliminate this painful while-loop
auto len = _vec.len[mutable uint](v1.storage);
auto i = 0u;
while (i < len) {
if (v0.storage.(i) != v1.storage.(i)) {
ret false;
}
i = i + 1u;
}
ret true;
}
impure fn clear(&t v) {
for each (uint i in _uint.range(0u, _vec.len[mutable uint](v.storage))) {
v.storage.(i) = 0u;
}
}
impure fn invert(&t v) {
for each (uint i in _uint.range(0u, _vec.len[mutable uint](v.storage))) {
v.storage.(i) = ~v.storage.(i);
}
}
/* v0 = v0 - v1 */
impure fn difference(&t v0, &t v1) -> bool {
invert(v1);
auto b = intersect(v0, v1);
invert(v1);
ret b;
}
impure fn set(&t v, uint i, bool x) {
check (i < v.nbits);
auto bits = uint_bits();
auto w = i / bits;
auto b = i % bits;
auto w0 = v.storage.(w);
auto flag = 1u << b;
if (x) {
v.storage.(w) = v.storage.(w) | flag;
} else {
v.storage.(w) = v.storage.(w) & ~flag;
}
}
fn init_to_vec(t v, uint i) -> uint {
if (get(v, i)) {
ret 1u;
} else {
ret 0u;
}
}
fn to_vec(&t v) -> vec[uint] {
auto sub = bind init_to_vec(v, _);
ret _vec.init_fn[uint](sub, v.nbits);
}
// FIXME: can we just use structural equality on to_vec?
fn eq_vec(&t v0, &vec[uint] v1) -> bool {
check (v0.nbits == _vec.len[uint](v1));
auto len = v0.nbits;
auto i = 0u;
while (i < len) {
auto w0 = get(v0, i);
auto w1 = v1.(i);
if ((!w0 && w1 != 0u) || (w0 && w1 == 0u)) {
ret false;
}
i = i + 1u;
}
ret true;
}
//
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// compile-command: "make -k -C .. 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
// End:
//
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