1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866
pub use crate::change_detection::{NonSendMut, Res, ResMut};
use crate::{
archetype::{Archetype, Archetypes},
bundle::Bundles,
change_detection::{Ticks, TicksMut},
component::{ComponentId, ComponentTicks, Components, Tick},
entity::Entities,
prelude::QueryBuilder,
query::{
Access, FilteredAccess, FilteredAccessSet, QueryData, QueryFilter, QueryState,
ReadOnlyQueryData,
},
system::{Query, SystemMeta},
world::{unsafe_world_cell::UnsafeWorldCell, DeferredWorld, FromWorld, World},
};
use bevy_ecs_macros::impl_param_set;
pub use bevy_ecs_macros::Resource;
pub use bevy_ecs_macros::SystemParam;
use bevy_ptr::UnsafeCellDeref;
use bevy_utils::{all_tuples, synccell::SyncCell};
use std::{
fmt::Debug,
marker::PhantomData,
ops::{Deref, DerefMut},
};
/// A parameter that can be used in a [`System`](super::System).
///
/// # Derive
///
/// This trait can be derived with the [`derive@super::SystemParam`] macro.
/// This macro only works if each field on the derived struct implements [`SystemParam`].
/// Note: There are additional requirements on the field types.
/// See the *Generic `SystemParam`s* section for details and workarounds of the probable
/// cause if this derive causes an error to be emitted.
///
/// Derived `SystemParam` structs may have two lifetimes: `'w` for data stored in the [`World`],
/// and `'s` for data stored in the parameter's state.
///
/// The following list shows the most common [`SystemParam`]s and which lifetime they require
///
/// ```
/// # use bevy_ecs::prelude::*;
/// # #[derive(Resource)]
/// # struct SomeResource;
/// # #[derive(Event)]
/// # struct SomeEvent;
/// # #[derive(Resource)]
/// # struct SomeOtherResource;
/// # use bevy_ecs::system::SystemParam;
/// # #[derive(SystemParam)]
/// # struct ParamsExample<'w, 's> {
/// # query:
/// Query<'w, 's, Entity>,
/// # res:
/// Res<'w, SomeResource>,
/// # res_mut:
/// ResMut<'w, SomeOtherResource>,
/// # local:
/// Local<'s, u8>,
/// # commands:
/// Commands<'w, 's>,
/// # eventreader:
/// EventReader<'w, 's, SomeEvent>,
/// # eventwriter:
/// EventWriter<'w, SomeEvent>
/// # }
///```
/// ## `PhantomData`
///
/// [`PhantomData`] is a special type of `SystemParam` that does nothing.
/// This is useful for constraining generic types or lifetimes.
///
/// # Example
///
/// ```
/// # use bevy_ecs::prelude::*;
/// # #[derive(Resource)]
/// # struct SomeResource;
/// use std::marker::PhantomData;
/// use bevy_ecs::system::SystemParam;
///
/// #[derive(SystemParam)]
/// struct MyParam<'w, Marker: 'static> {
/// foo: Res<'w, SomeResource>,
/// marker: PhantomData<Marker>,
/// }
///
/// fn my_system<T: 'static>(param: MyParam<T>) {
/// // Access the resource through `param.foo`
/// }
///
/// # bevy_ecs::system::assert_is_system(my_system::<()>);
/// ```
///
/// # Generic `SystemParam`s
///
/// When using the derive macro, you may see an error in the form of:
///
/// ```text
/// expected ... [ParamType]
/// found associated type `<[ParamType] as SystemParam>::Item<'_, '_>`
/// ```
/// where `[ParamType]` is the type of one of your fields.
/// To solve this error, you can wrap the field of type `[ParamType]` with [`StaticSystemParam`]
/// (i.e. `StaticSystemParam<[ParamType]>`).
///
/// ## Details
///
/// The derive macro requires that the [`SystemParam`] implementation of
/// each field `F`'s [`Item`](`SystemParam::Item`)'s is itself `F`
/// (ignoring lifetimes for simplicity).
/// This assumption is due to type inference reasons, so that the derived [`SystemParam`] can be
/// used as an argument to a function system.
/// If the compiler cannot validate this property for `[ParamType]`, it will error in the form shown above.
///
/// This will most commonly occur when working with `SystemParam`s generically, as the requirement
/// has not been proven to the compiler.
///
/// # Safety
///
/// The implementor must ensure the following is true.
/// - [`SystemParam::init_state`] correctly registers all [`World`] accesses used
/// by [`SystemParam::get_param`] with the provided [`system_meta`](SystemMeta).
/// - None of the world accesses may conflict with any prior accesses registered
/// on `system_meta`.
pub unsafe trait SystemParam: Sized {
/// Used to store data which persists across invocations of a system.
type State: Send + Sync + 'static;
/// The item type returned when constructing this system param.
/// The value of this associated type should be `Self`, instantiated with new lifetimes.
///
/// You could think of `SystemParam::Item<'w, 's>` as being an *operation* that changes the lifetimes bound to `Self`.
type Item<'world, 'state>: SystemParam<State = Self::State>;
/// Registers any [`World`] access used by this [`SystemParam`]
/// and creates a new instance of this param's [`State`](Self::State).
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State;
/// For the specified [`Archetype`], registers the components accessed by this [`SystemParam`] (if applicable).a
///
/// # Safety
/// `archetype` must be from the [`World`] used to initialize `state` in `init_state`.
#[inline]
#[allow(unused_variables)]
unsafe fn new_archetype(
state: &mut Self::State,
archetype: &Archetype,
system_meta: &mut SystemMeta,
) {
}
/// Applies any deferred mutations stored in this [`SystemParam`]'s state.
/// This is used to apply [`Commands`] during [`apply_deferred`](crate::prelude::apply_deferred).
///
/// [`Commands`]: crate::prelude::Commands
#[inline]
#[allow(unused_variables)]
fn apply(state: &mut Self::State, system_meta: &SystemMeta, world: &mut World) {}
/// Queues any deferred mutations to be applied at the next [`apply_deferred`](crate::prelude::apply_deferred).
#[inline]
#[allow(unused_variables)]
fn queue(state: &mut Self::State, system_meta: &SystemMeta, world: DeferredWorld) {}
/// Creates a parameter to be passed into a [`SystemParamFunction`].
///
/// [`SystemParamFunction`]: super::SystemParamFunction
///
/// # Safety
///
/// - The passed [`UnsafeWorldCell`] must have access to any world data
/// registered in [`init_state`](SystemParam::init_state).
/// - `world` must be the same `World` that was used to initialize [`state`](SystemParam::init_state).
unsafe fn get_param<'world, 'state>(
state: &'state mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'world>,
change_tick: Tick,
) -> Self::Item<'world, 'state>;
}
/// A parameter that can be built with [`SystemBuilder`](crate::system::builder::SystemBuilder)
pub trait BuildableSystemParam: SystemParam {
/// A mutable reference to this type will be passed to the builder function
type Builder<'b>;
/// Constructs [`SystemParam::State`] for `Self` using a given builder function
fn build(
world: &mut World,
meta: &mut SystemMeta,
func: impl FnOnce(&mut Self::Builder<'_>),
) -> Self::State;
}
/// A [`SystemParam`] that only reads a given [`World`].
///
/// # Safety
/// This must only be implemented for [`SystemParam`] impls that exclusively read the World passed in to [`SystemParam::get_param`]
pub unsafe trait ReadOnlySystemParam: SystemParam {}
/// Shorthand way of accessing the associated type [`SystemParam::Item`] for a given [`SystemParam`].
pub type SystemParamItem<'w, 's, P> = <P as SystemParam>::Item<'w, 's>;
// SAFETY: QueryState is constrained to read-only fetches, so it only reads World.
unsafe impl<'w, 's, D: ReadOnlyQueryData + 'static, F: QueryFilter + 'static> ReadOnlySystemParam
for Query<'w, 's, D, F>
{
}
// SAFETY: Relevant query ComponentId and ArchetypeComponentId access is applied to SystemMeta. If
// this Query conflicts with any prior access, a panic will occur.
unsafe impl<D: QueryData + 'static, F: QueryFilter + 'static> SystemParam for Query<'_, '_, D, F> {
type State = QueryState<D, F>;
type Item<'w, 's> = Query<'w, 's, D, F>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
let state = QueryState::new_with_access(world, &mut system_meta.archetype_component_access);
assert_component_access_compatibility(
&system_meta.name,
std::any::type_name::<D>(),
std::any::type_name::<F>(),
&system_meta.component_access_set,
&state.component_access,
world,
);
system_meta
.component_access_set
.add(state.component_access.clone());
state
}
unsafe fn new_archetype(
state: &mut Self::State,
archetype: &Archetype,
system_meta: &mut SystemMeta,
) {
state.new_archetype(archetype, &mut system_meta.archetype_component_access);
}
#[inline]
unsafe fn get_param<'w, 's>(
state: &'s mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
change_tick: Tick,
) -> Self::Item<'w, 's> {
// SAFETY: We have registered all of the query's world accesses,
// so the caller ensures that `world` has permission to access any
// world data that the query needs.
unsafe { Query::new(world, state, system_meta.last_run, change_tick) }
}
}
impl<'w, 's, D: QueryData + 'static, F: QueryFilter + 'static> BuildableSystemParam
for Query<'w, 's, D, F>
{
type Builder<'b> = QueryBuilder<'b, D, F>;
#[inline]
fn build(
world: &mut World,
system_meta: &mut SystemMeta,
build: impl FnOnce(&mut Self::Builder<'_>),
) -> Self::State {
let mut builder = QueryBuilder::new(world);
build(&mut builder);
let state = builder.build();
assert_component_access_compatibility(
&system_meta.name,
std::any::type_name::<D>(),
std::any::type_name::<F>(),
&system_meta.component_access_set,
&state.component_access,
world,
);
system_meta
.component_access_set
.add(state.component_access.clone());
state
}
}
fn assert_component_access_compatibility(
system_name: &str,
query_type: &'static str,
filter_type: &'static str,
system_access: &FilteredAccessSet<ComponentId>,
current: &FilteredAccess<ComponentId>,
world: &World,
) {
let conflicts = system_access.get_conflicts_single(current);
if conflicts.is_empty() {
return;
}
let conflicting_components = conflicts
.into_iter()
.map(|component_id| world.components.get_info(component_id).unwrap().name())
.collect::<Vec<&str>>();
let accesses = conflicting_components.join(", ");
panic!("error[B0001]: Query<{query_type}, {filter_type}> in system {system_name} accesses component(s) {accesses} in a way that conflicts with a previous system parameter. Consider using `Without<T>` to create disjoint Queries or merging conflicting Queries into a `ParamSet`. See: https://bevyengine.org/learn/errors/#b0001");
}
/// A collection of potentially conflicting [`SystemParam`]s allowed by disjoint access.
///
/// Allows systems to safely access and interact with up to 8 mutually exclusive [`SystemParam`]s, such as
/// two queries that reference the same mutable data or an event reader and writer of the same type.
///
/// Each individual [`SystemParam`] can be accessed by using the functions `p0()`, `p1()`, ..., `p7()`,
/// according to the order they are defined in the `ParamSet`. This ensures that there's either
/// only one mutable reference to a parameter at a time or any number of immutable references.
///
/// # Examples
///
/// The following system mutably accesses the same component two times,
/// which is not allowed due to rust's mutability rules.
///
/// ```should_panic
/// # use bevy_ecs::prelude::*;
/// #
/// # #[derive(Component)]
/// # struct Health;
/// #
/// # #[derive(Component)]
/// # struct Enemy;
/// #
/// # #[derive(Component)]
/// # struct Ally;
/// #
/// // This will panic at runtime when the system gets initialized.
/// fn bad_system(
/// mut enemies: Query<&mut Health, With<Enemy>>,
/// mut allies: Query<&mut Health, With<Ally>>,
/// ) {
/// // ...
/// }
/// #
/// # let mut bad_system_system = IntoSystem::into_system(bad_system);
/// # let mut world = World::new();
/// # bad_system_system.initialize(&mut world);
/// # bad_system_system.run((), &mut world);
/// ```
///
/// Conflicting `SystemParam`s like these can be placed in a `ParamSet`,
/// which leverages the borrow checker to ensure that only one of the contained parameters are accessed at a given time.
///
/// ```
/// # use bevy_ecs::prelude::*;
/// #
/// # #[derive(Component)]
/// # struct Health;
/// #
/// # #[derive(Component)]
/// # struct Enemy;
/// #
/// # #[derive(Component)]
/// # struct Ally;
/// #
/// // Given the following system
/// fn fancy_system(
/// mut set: ParamSet<(
/// Query<&mut Health, With<Enemy>>,
/// Query<&mut Health, With<Ally>>,
/// )>
/// ) {
/// // This will access the first `SystemParam`.
/// for mut health in set.p0().iter_mut() {
/// // Do your fancy stuff here...
/// }
///
/// // The second `SystemParam`.
/// // This would fail to compile if the previous parameter was still borrowed.
/// for mut health in set.p1().iter_mut() {
/// // Do even fancier stuff here...
/// }
/// }
/// # bevy_ecs::system::assert_is_system(fancy_system);
/// ```
///
/// Of course, `ParamSet`s can be used with any kind of `SystemParam`, not just [queries](Query).
///
/// ```
/// # use bevy_ecs::prelude::*;
/// #
/// # #[derive(Event)]
/// # struct MyEvent;
/// # impl MyEvent {
/// # pub fn new() -> Self { Self }
/// # }
/// fn event_system(
/// mut set: ParamSet<(
/// // `EventReader`s and `EventWriter`s conflict with each other,
/// // since they both access the event queue resource for `MyEvent`.
/// EventReader<MyEvent>,
/// EventWriter<MyEvent>,
/// // `&World` reads the entire world, so a `ParamSet` is the only way
/// // that it can be used in the same system as any mutable accesses.
/// &World,
/// )>,
/// ) {
/// for event in set.p0().read() {
/// // ...
/// # let _event = event;
/// }
/// set.p1().send(MyEvent::new());
///
/// let entities = set.p2().entities();
/// // ...
/// # let _entities = entities;
/// }
/// # bevy_ecs::system::assert_is_system(event_system);
/// ```
pub struct ParamSet<'w, 's, T: SystemParam> {
param_states: &'s mut T::State,
world: UnsafeWorldCell<'w>,
system_meta: SystemMeta,
change_tick: Tick,
}
impl_param_set!();
/// A type that can be inserted into a [`World`] as a singleton.
///
/// You can access resource data in systems using the [`Res`] and [`ResMut`] system parameters
///
/// Only one resource of each type can be stored in a [`World`] at any given time.
///
/// # Examples
///
/// ```
/// # let mut world = World::default();
/// # let mut schedule = Schedule::default();
/// # use bevy_ecs::prelude::*;
/// #[derive(Resource)]
/// struct MyResource { value: u32 }
///
/// world.insert_resource(MyResource { value: 42 });
///
/// fn read_resource_system(resource: Res<MyResource>) {
/// assert_eq!(resource.value, 42);
/// }
///
/// fn write_resource_system(mut resource: ResMut<MyResource>) {
/// assert_eq!(resource.value, 42);
/// resource.value = 0;
/// assert_eq!(resource.value, 0);
/// }
/// # schedule.add_systems((read_resource_system, write_resource_system).chain());
/// # schedule.run(&mut world);
/// ```
///
/// # `!Sync` Resources
/// A `!Sync` type cannot implement `Resource`. However, it is possible to wrap a `Send` but not `Sync`
/// type in [`SyncCell`] or the currently unstable [`Exclusive`] to make it `Sync`. This forces only
/// having mutable access (`&mut T` only, never `&T`), but makes it safe to reference across multiple
/// threads.
///
/// This will fail to compile since `RefCell` is `!Sync`.
/// ```compile_fail
/// # use std::cell::RefCell;
/// # use bevy_ecs::system::Resource;
///
/// #[derive(Resource)]
/// struct NotSync {
/// counter: RefCell<usize>,
/// }
/// ```
///
/// This will compile since the `RefCell` is wrapped with `SyncCell`.
/// ```
/// # use std::cell::RefCell;
/// # use bevy_ecs::system::Resource;
/// use bevy_utils::synccell::SyncCell;
///
/// #[derive(Resource)]
/// struct ActuallySync {
/// counter: SyncCell<RefCell<usize>>,
/// }
/// ```
///
/// [`Exclusive`]: https://doc.rust-lang.org/nightly/std/sync/struct.Exclusive.html
#[diagnostic::on_unimplemented(
message = "`{Self}` is not a `Resource`",
label = "invalid `Resource`",
note = "consider annotating `{Self}` with `#[derive(Resource)]`"
)]
pub trait Resource: Send + Sync + 'static {}
// SAFETY: Res only reads a single World resource
unsafe impl<'a, T: Resource> ReadOnlySystemParam for Res<'a, T> {}
// SAFETY: Res ComponentId and ArchetypeComponentId access is applied to SystemMeta. If this Res
// conflicts with any prior access, a panic will occur.
unsafe impl<'a, T: Resource> SystemParam for Res<'a, T> {
type State = ComponentId;
type Item<'w, 's> = Res<'w, T>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
let component_id = world.components.init_resource::<T>();
world.initialize_resource_internal(component_id);
let combined_access = system_meta.component_access_set.combined_access();
assert!(
!combined_access.has_write(component_id),
"error[B0002]: Res<{}> in system {} conflicts with a previous ResMut<{0}> access. Consider removing the duplicate access. See: https://bevyengine.org/learn/errors/#b0002",
std::any::type_name::<T>(),
system_meta.name,
);
system_meta
.component_access_set
.add_unfiltered_read(component_id);
let archetype_component_id = world
.get_resource_archetype_component_id(component_id)
.unwrap();
system_meta
.archetype_component_access
.add_read(archetype_component_id);
component_id
}
#[inline]
unsafe fn get_param<'w, 's>(
&mut component_id: &'s mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
change_tick: Tick,
) -> Self::Item<'w, 's> {
let (ptr, ticks) = world
.get_resource_with_ticks(component_id)
.unwrap_or_else(|| {
panic!(
"Resource requested by {} does not exist: {}",
system_meta.name,
std::any::type_name::<T>()
)
});
Res {
value: ptr.deref(),
ticks: Ticks {
added: ticks.added.deref(),
changed: ticks.changed.deref(),
last_run: system_meta.last_run,
this_run: change_tick,
},
}
}
}
// SAFETY: Only reads a single World resource
unsafe impl<'a, T: Resource> ReadOnlySystemParam for Option<Res<'a, T>> {}
// SAFETY: this impl defers to `Res`, which initializes and validates the correct world access.
unsafe impl<'a, T: Resource> SystemParam for Option<Res<'a, T>> {
type State = ComponentId;
type Item<'w, 's> = Option<Res<'w, T>>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
Res::<T>::init_state(world, system_meta)
}
#[inline]
unsafe fn get_param<'w, 's>(
&mut component_id: &'s mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
change_tick: Tick,
) -> Self::Item<'w, 's> {
world
.get_resource_with_ticks(component_id)
.map(|(ptr, ticks)| Res {
value: ptr.deref(),
ticks: Ticks {
added: ticks.added.deref(),
changed: ticks.changed.deref(),
last_run: system_meta.last_run,
this_run: change_tick,
},
})
}
}
// SAFETY: Res ComponentId and ArchetypeComponentId access is applied to SystemMeta. If this Res
// conflicts with any prior access, a panic will occur.
unsafe impl<'a, T: Resource> SystemParam for ResMut<'a, T> {
type State = ComponentId;
type Item<'w, 's> = ResMut<'w, T>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
let component_id = world.components.init_resource::<T>();
world.initialize_resource_internal(component_id);
let combined_access = system_meta.component_access_set.combined_access();
if combined_access.has_write(component_id) {
panic!(
"error[B0002]: ResMut<{}> in system {} conflicts with a previous ResMut<{0}> access. Consider removing the duplicate access. See: https://bevyengine.org/learn/errors/#b0002",
std::any::type_name::<T>(), system_meta.name);
} else if combined_access.has_read(component_id) {
panic!(
"error[B0002]: ResMut<{}> in system {} conflicts with a previous Res<{0}> access. Consider removing the duplicate access. See: https://bevyengine.org/learn/errors/#b0002",
std::any::type_name::<T>(), system_meta.name);
}
system_meta
.component_access_set
.add_unfiltered_write(component_id);
let archetype_component_id = world
.get_resource_archetype_component_id(component_id)
.unwrap();
system_meta
.archetype_component_access
.add_write(archetype_component_id);
component_id
}
#[inline]
unsafe fn get_param<'w, 's>(
&mut component_id: &'s mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
change_tick: Tick,
) -> Self::Item<'w, 's> {
let value = world
.get_resource_mut_by_id(component_id)
.unwrap_or_else(|| {
panic!(
"Resource requested by {} does not exist: {}",
system_meta.name,
std::any::type_name::<T>()
)
});
ResMut {
value: value.value.deref_mut::<T>(),
ticks: TicksMut {
added: value.ticks.added,
changed: value.ticks.changed,
last_run: system_meta.last_run,
this_run: change_tick,
},
}
}
}
// SAFETY: this impl defers to `ResMut`, which initializes and validates the correct world access.
unsafe impl<'a, T: Resource> SystemParam for Option<ResMut<'a, T>> {
type State = ComponentId;
type Item<'w, 's> = Option<ResMut<'w, T>>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
ResMut::<T>::init_state(world, system_meta)
}
#[inline]
unsafe fn get_param<'w, 's>(
&mut component_id: &'s mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
change_tick: Tick,
) -> Self::Item<'w, 's> {
world
.get_resource_mut_by_id(component_id)
.map(|value| ResMut {
value: value.value.deref_mut::<T>(),
ticks: TicksMut {
added: value.ticks.added,
changed: value.ticks.changed,
last_run: system_meta.last_run,
this_run: change_tick,
},
})
}
}
/// SAFETY: only reads world
unsafe impl<'w> ReadOnlySystemParam for &'w World {}
// SAFETY: `read_all` access is set and conflicts result in a panic
unsafe impl SystemParam for &'_ World {
type State = ();
type Item<'w, 's> = &'w World;
fn init_state(_world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
let mut access = Access::default();
access.read_all();
if !system_meta
.archetype_component_access
.is_compatible(&access)
{
panic!("&World conflicts with a previous mutable system parameter. Allowing this would break Rust's mutability rules");
}
system_meta.archetype_component_access.extend(&access);
let mut filtered_access = FilteredAccess::default();
filtered_access.read_all();
if !system_meta
.component_access_set
.get_conflicts_single(&filtered_access)
.is_empty()
{
panic!("&World conflicts with a previous mutable system parameter. Allowing this would break Rust's mutability rules");
}
system_meta.component_access_set.add(filtered_access);
}
unsafe fn get_param<'w, 's>(
_state: &'s mut Self::State,
_system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
_change_tick: Tick,
) -> Self::Item<'w, 's> {
// SAFETY: Read-only access to the entire world was registered in `init_state`.
unsafe { world.world() }
}
}
/// SAFETY: `DeferredWorld` can read all components and resources but cannot be used to gain any other mutable references.
unsafe impl<'w> SystemParam for DeferredWorld<'w> {
type State = ();
type Item<'world, 'state> = DeferredWorld<'world>;
fn init_state(_world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
system_meta.component_access_set.read_all();
system_meta.component_access_set.write_all();
system_meta.set_has_deferred();
}
unsafe fn get_param<'world, 'state>(
_state: &'state mut Self::State,
_system_meta: &SystemMeta,
world: UnsafeWorldCell<'world>,
_change_tick: Tick,
) -> Self::Item<'world, 'state> {
world.into_deferred()
}
}
/// A system local [`SystemParam`].
///
/// A local may only be accessed by the system itself and is therefore not visible to other systems.
/// If two or more systems specify the same local type each will have their own unique local.
/// If multiple [`SystemParam`]s within the same system each specify the same local type
/// each will get their own distinct data storage.
///
/// The supplied lifetime parameter is the [`SystemParam`]s `'s` lifetime.
///
/// # Examples
///
/// ```
/// # use bevy_ecs::prelude::*;
/// # let world = &mut World::default();
/// fn write_to_local(mut local: Local<usize>) {
/// *local = 42;
/// }
/// fn read_from_local(local: Local<usize>) -> usize {
/// *local
/// }
/// let mut write_system = IntoSystem::into_system(write_to_local);
/// let mut read_system = IntoSystem::into_system(read_from_local);
/// write_system.initialize(world);
/// read_system.initialize(world);
///
/// assert_eq!(read_system.run((), world), 0);
/// write_system.run((), world);
/// // Note how the read local is still 0 due to the locals not being shared.
/// assert_eq!(read_system.run((), world), 0);
/// ```
///
/// N.B. A [`Local`]s value cannot be read or written to outside of the containing system.
/// To add configuration to a system, convert a capturing closure into the system instead:
///
/// ```
/// # use bevy_ecs::prelude::*;
/// # use bevy_ecs::system::assert_is_system;
/// struct Config(u32);
/// #[derive(Resource)]
/// struct MyU32Wrapper(u32);
/// fn reset_to_system(value: Config) -> impl FnMut(ResMut<MyU32Wrapper>) {
/// move |mut val| val.0 = value.0
/// }
///
/// // .add_systems(reset_to_system(my_config))
/// # assert_is_system(reset_to_system(Config(10)));
/// ```
#[derive(Debug)]
pub struct Local<'s, T: FromWorld + Send + 'static>(pub(crate) &'s mut T);
// SAFETY: Local only accesses internal state
unsafe impl<'s, T: FromWorld + Send + 'static> ReadOnlySystemParam for Local<'s, T> {}
impl<'s, T: FromWorld + Send + 'static> Deref for Local<'s, T> {
type Target = T;
#[inline]
fn deref(&self) -> &Self::Target {
self.0
}
}
impl<'s, T: FromWorld + Send + 'static> DerefMut for Local<'s, T> {
#[inline]
fn deref_mut(&mut self) -> &mut Self::Target {
self.0
}
}
impl<'s, 'a, T: FromWorld + Send + 'static> IntoIterator for &'a Local<'s, T>
where
&'a T: IntoIterator,
{
type Item = <&'a T as IntoIterator>::Item;
type IntoIter = <&'a T as IntoIterator>::IntoIter;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
}
}
impl<'s, 'a, T: FromWorld + Send + 'static> IntoIterator for &'a mut Local<'s, T>
where
&'a mut T: IntoIterator,
{
type Item = <&'a mut T as IntoIterator>::Item;
type IntoIter = <&'a mut T as IntoIterator>::IntoIter;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
}
}
// SAFETY: only local state is accessed
unsafe impl<'a, T: FromWorld + Send + 'static> SystemParam for Local<'a, T> {
type State = SyncCell<T>;
type Item<'w, 's> = Local<'s, T>;
fn init_state(world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {
SyncCell::new(T::from_world(world))
}
#[inline]
unsafe fn get_param<'w, 's>(
state: &'s mut Self::State,
_system_meta: &SystemMeta,
_world: UnsafeWorldCell<'w>,
_change_tick: Tick,
) -> Self::Item<'w, 's> {
Local(state.get())
}
}
impl<'w, T: FromWorld + Send + 'static> BuildableSystemParam for Local<'w, T> {
type Builder<'b> = T;
fn build(
world: &mut World,
_meta: &mut SystemMeta,
func: impl FnOnce(&mut Self::Builder<'_>),
) -> Self::State {
let mut value = T::from_world(world);
func(&mut value);
SyncCell::new(value)
}
}
/// Types that can be used with [`Deferred<T>`] in systems.
/// This allows storing system-local data which is used to defer [`World`] mutations.
///
/// Types that implement `SystemBuffer` should take care to perform as many
/// computations up-front as possible. Buffers cannot be applied in parallel,
/// so you should try to minimize the time spent in [`SystemBuffer::apply`].
pub trait SystemBuffer: FromWorld + Send + 'static {
/// Applies any deferred mutations to the [`World`].
fn apply(&mut self, system_meta: &SystemMeta, world: &mut World);
/// Queues any deferred mutations to be applied at the next [`apply_deferred`](crate::prelude::apply_deferred).
fn queue(&mut self, _system_meta: &SystemMeta, _world: DeferredWorld) {}
}
/// A [`SystemParam`] that stores a buffer which gets applied to the [`World`] during
/// [`apply_deferred`](crate::schedule::apply_deferred).
/// This is used internally by [`Commands`] to defer `World` mutations.
///
/// [`Commands`]: crate::system::Commands
///
/// # Examples
///
/// By using this type to defer mutations, you can avoid mutable `World` access within
/// a system, which allows it to run in parallel with more systems.
///
/// Note that deferring mutations is *not* free, and should only be used if
/// the gains in parallelization outweigh the time it takes to apply deferred mutations.
/// In general, [`Deferred`] should only be used for mutations that are infrequent,
/// or which otherwise take up a small portion of a system's run-time.
///
/// ```
/// # use bevy_ecs::prelude::*;
/// // Tracks whether or not there is a threat the player should be aware of.
/// #[derive(Resource, Default)]
/// pub struct Alarm(bool);
///
/// #[derive(Component)]
/// pub struct Settlement {
/// // ...
/// }
///
/// // A threat from inside the settlement.
/// #[derive(Component)]
/// pub struct Criminal;
///
/// // A threat from outside the settlement.
/// #[derive(Component)]
/// pub struct Monster;
///
/// # impl Criminal { pub fn is_threat(&self, _: &Settlement) -> bool { true } }
///
/// use bevy_ecs::system::{Deferred, SystemBuffer, SystemMeta};
///
/// // Uses deferred mutations to allow signalling the alarm from multiple systems in parallel.
/// #[derive(Resource, Default)]
/// struct AlarmFlag(bool);
///
/// impl AlarmFlag {
/// /// Sounds the alarm the next time buffers are applied via apply_deferred.
/// pub fn flag(&mut self) {
/// self.0 = true;
/// }
/// }
///
/// impl SystemBuffer for AlarmFlag {
/// // When `AlarmFlag` is used in a system, this function will get
/// // called the next time buffers are applied via apply_deferred.
/// fn apply(&mut self, system_meta: &SystemMeta, world: &mut World) {
/// if self.0 {
/// world.resource_mut::<Alarm>().0 = true;
/// self.0 = false;
/// }
/// }
/// }
///
/// // Sound the alarm if there are any criminals who pose a threat.
/// fn alert_criminal(
/// settlements: Query<&Settlement>,
/// criminals: Query<&Criminal>,
/// mut alarm: Deferred<AlarmFlag>
/// ) {
/// let settlement = settlements.single();
/// for criminal in &criminals {
/// // Only sound the alarm if the criminal is a threat.
/// // For this example, assume that this check is expensive to run.
/// // Since the majority of this system's run-time is dominated
/// // by calling `is_threat()`, we defer sounding the alarm to
/// // allow this system to run in parallel with other alarm systems.
/// if criminal.is_threat(settlement) {
/// alarm.flag();
/// }
/// }
/// }
///
/// // Sound the alarm if there is a monster.
/// fn alert_monster(
/// monsters: Query<&Monster>,
/// mut alarm: ResMut<Alarm>
/// ) {
/// if monsters.iter().next().is_some() {
/// // Since this system does nothing except for sounding the alarm,
/// // it would be pointless to defer it, so we sound the alarm directly.
/// alarm.0 = true;
/// }
/// }
///
/// let mut world = World::new();
/// world.init_resource::<Alarm>();
/// world.spawn(Settlement {
/// // ...
/// });
///
/// let mut schedule = Schedule::default();
/// // These two systems have no conflicts and will run in parallel.
/// schedule.add_systems((alert_criminal, alert_monster));
///
/// // There are no criminals or monsters, so the alarm is not sounded.
/// schedule.run(&mut world);
/// assert_eq!(world.resource::<Alarm>().0, false);
///
/// // Spawn a monster, which will cause the alarm to be sounded.
/// let m_id = world.spawn(Monster).id();
/// schedule.run(&mut world);
/// assert_eq!(world.resource::<Alarm>().0, true);
///
/// // Remove the monster and reset the alarm.
/// world.entity_mut(m_id).despawn();
/// world.resource_mut::<Alarm>().0 = false;
///
/// // Spawn a criminal, which will cause the alarm to be sounded.
/// world.spawn(Criminal);
/// schedule.run(&mut world);
/// assert_eq!(world.resource::<Alarm>().0, true);
/// ```
pub struct Deferred<'a, T: SystemBuffer>(pub(crate) &'a mut T);
impl<'a, T: SystemBuffer> Deref for Deferred<'a, T> {
type Target = T;
#[inline]
fn deref(&self) -> &Self::Target {
self.0
}
}
impl<'a, T: SystemBuffer> DerefMut for Deferred<'a, T> {
#[inline]
fn deref_mut(&mut self) -> &mut Self::Target {
self.0
}
}
impl<T: SystemBuffer> Deferred<'_, T> {
/// Returns a [`Deferred<T>`] with a smaller lifetime.
/// This is useful if you have `&mut Deferred<T>` but need `Deferred<T>`.
pub fn reborrow(&mut self) -> Deferred<T> {
Deferred(self.0)
}
}
// SAFETY: Only local state is accessed.
unsafe impl<T: SystemBuffer> ReadOnlySystemParam for Deferred<'_, T> {}
// SAFETY: Only local state is accessed.
unsafe impl<T: SystemBuffer> SystemParam for Deferred<'_, T> {
type State = SyncCell<T>;
type Item<'w, 's> = Deferred<'s, T>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
system_meta.set_has_deferred();
SyncCell::new(T::from_world(world))
}
fn apply(state: &mut Self::State, system_meta: &SystemMeta, world: &mut World) {
state.get().apply(system_meta, world);
}
fn queue(state: &mut Self::State, system_meta: &SystemMeta, world: DeferredWorld) {
state.get().queue(system_meta, world);
}
unsafe fn get_param<'w, 's>(
state: &'s mut Self::State,
_system_meta: &SystemMeta,
_world: UnsafeWorldCell<'w>,
_change_tick: Tick,
) -> Self::Item<'w, 's> {
Deferred(state.get())
}
}
/// Shared borrow of a non-[`Send`] resource.
///
/// Only `Send` resources may be accessed with the [`Res`] [`SystemParam`]. In case that the
/// resource does not implement `Send`, this `SystemParam` wrapper can be used. This will instruct
/// the scheduler to instead run the system on the main thread so that it doesn't send the resource
/// over to another thread.
///
/// # Panics
///
/// Panics when used as a `SystemParameter` if the resource does not exist.
///
/// Use `Option<NonSend<T>>` instead if the resource might not always exist.
pub struct NonSend<'w, T: 'static> {
pub(crate) value: &'w T,
ticks: ComponentTicks,
last_run: Tick,
this_run: Tick,
}
// SAFETY: Only reads a single World non-send resource
unsafe impl<'w, T> ReadOnlySystemParam for NonSend<'w, T> {}
impl<'w, T> Debug for NonSend<'w, T>
where
T: Debug,
{
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_tuple("NonSend").field(&self.value).finish()
}
}
impl<'w, T: 'static> NonSend<'w, T> {
/// Returns `true` if the resource was added after the system last ran.
pub fn is_added(&self) -> bool {
self.ticks.is_added(self.last_run, self.this_run)
}
/// Returns `true` if the resource was added or mutably dereferenced after the system last ran.
pub fn is_changed(&self) -> bool {
self.ticks.is_changed(self.last_run, self.this_run)
}
}
impl<'w, T> Deref for NonSend<'w, T> {
type Target = T;
fn deref(&self) -> &Self::Target {
self.value
}
}
impl<'a, T> From<NonSendMut<'a, T>> for NonSend<'a, T> {
fn from(nsm: NonSendMut<'a, T>) -> Self {
Self {
value: nsm.value,
ticks: ComponentTicks {
added: nsm.ticks.added.to_owned(),
changed: nsm.ticks.changed.to_owned(),
},
this_run: nsm.ticks.this_run,
last_run: nsm.ticks.last_run,
}
}
}
// SAFETY: NonSendComponentId and ArchetypeComponentId access is applied to SystemMeta. If this
// NonSend conflicts with any prior access, a panic will occur.
unsafe impl<'a, T: 'static> SystemParam for NonSend<'a, T> {
type State = ComponentId;
type Item<'w, 's> = NonSend<'w, T>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
system_meta.set_non_send();
let component_id = world.components.init_non_send::<T>();
world.initialize_non_send_internal(component_id);
let combined_access = system_meta.component_access_set.combined_access();
assert!(
!combined_access.has_write(component_id),
"error[B0002]: NonSend<{}> in system {} conflicts with a previous mutable resource access ({0}). Consider removing the duplicate access. See: https://bevyengine.org/learn/errors/#b0002",
std::any::type_name::<T>(),
system_meta.name,
);
system_meta
.component_access_set
.add_unfiltered_read(component_id);
let archetype_component_id = world
.get_non_send_archetype_component_id(component_id)
.unwrap();
system_meta
.archetype_component_access
.add_read(archetype_component_id);
component_id
}
#[inline]
unsafe fn get_param<'w, 's>(
&mut component_id: &'s mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
change_tick: Tick,
) -> Self::Item<'w, 's> {
let (ptr, ticks) = world
.get_non_send_with_ticks(component_id)
.unwrap_or_else(|| {
panic!(
"Non-send resource requested by {} does not exist: {}",
system_meta.name,
std::any::type_name::<T>()
)
});
NonSend {
value: ptr.deref(),
ticks: ticks.read(),
last_run: system_meta.last_run,
this_run: change_tick,
}
}
}
// SAFETY: Only reads a single World non-send resource
unsafe impl<T: 'static> ReadOnlySystemParam for Option<NonSend<'_, T>> {}
// SAFETY: this impl defers to `NonSend`, which initializes and validates the correct world access.
unsafe impl<T: 'static> SystemParam for Option<NonSend<'_, T>> {
type State = ComponentId;
type Item<'w, 's> = Option<NonSend<'w, T>>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
NonSend::<T>::init_state(world, system_meta)
}
#[inline]
unsafe fn get_param<'w, 's>(
&mut component_id: &'s mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
change_tick: Tick,
) -> Self::Item<'w, 's> {
world
.get_non_send_with_ticks(component_id)
.map(|(ptr, ticks)| NonSend {
value: ptr.deref(),
ticks: ticks.read(),
last_run: system_meta.last_run,
this_run: change_tick,
})
}
}
// SAFETY: NonSendMut ComponentId and ArchetypeComponentId access is applied to SystemMeta. If this
// NonSendMut conflicts with any prior access, a panic will occur.
unsafe impl<'a, T: 'static> SystemParam for NonSendMut<'a, T> {
type State = ComponentId;
type Item<'w, 's> = NonSendMut<'w, T>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
system_meta.set_non_send();
let component_id = world.components.init_non_send::<T>();
world.initialize_non_send_internal(component_id);
let combined_access = system_meta.component_access_set.combined_access();
if combined_access.has_write(component_id) {
panic!(
"error[B0002]: NonSendMut<{}> in system {} conflicts with a previous mutable resource access ({0}). Consider removing the duplicate access. See: https://bevyengine.org/learn/errors/#b0002",
std::any::type_name::<T>(), system_meta.name);
} else if combined_access.has_read(component_id) {
panic!(
"error[B0002]: NonSendMut<{}> in system {} conflicts with a previous immutable resource access ({0}). Consider removing the duplicate access. See: https://bevyengine.org/learn/errors/#b0002",
std::any::type_name::<T>(), system_meta.name);
}
system_meta
.component_access_set
.add_unfiltered_write(component_id);
let archetype_component_id = world
.get_non_send_archetype_component_id(component_id)
.unwrap();
system_meta
.archetype_component_access
.add_write(archetype_component_id);
component_id
}
#[inline]
unsafe fn get_param<'w, 's>(
&mut component_id: &'s mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
change_tick: Tick,
) -> Self::Item<'w, 's> {
let (ptr, ticks) = world
.get_non_send_with_ticks(component_id)
.unwrap_or_else(|| {
panic!(
"Non-send resource requested by {} does not exist: {}",
system_meta.name,
std::any::type_name::<T>()
)
});
NonSendMut {
value: ptr.assert_unique().deref_mut(),
ticks: TicksMut::from_tick_cells(ticks, system_meta.last_run, change_tick),
}
}
}
// SAFETY: this impl defers to `NonSendMut`, which initializes and validates the correct world access.
unsafe impl<'a, T: 'static> SystemParam for Option<NonSendMut<'a, T>> {
type State = ComponentId;
type Item<'w, 's> = Option<NonSendMut<'w, T>>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
NonSendMut::<T>::init_state(world, system_meta)
}
#[inline]
unsafe fn get_param<'w, 's>(
&mut component_id: &'s mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
change_tick: Tick,
) -> Self::Item<'w, 's> {
world
.get_non_send_with_ticks(component_id)
.map(|(ptr, ticks)| NonSendMut {
value: ptr.assert_unique().deref_mut(),
ticks: TicksMut::from_tick_cells(ticks, system_meta.last_run, change_tick),
})
}
}
// SAFETY: Only reads World archetypes
unsafe impl<'a> ReadOnlySystemParam for &'a Archetypes {}
// SAFETY: no component value access
unsafe impl<'a> SystemParam for &'a Archetypes {
type State = ();
type Item<'w, 's> = &'w Archetypes;
fn init_state(_world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {}
#[inline]
unsafe fn get_param<'w, 's>(
_state: &'s mut Self::State,
_system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
_change_tick: Tick,
) -> Self::Item<'w, 's> {
world.archetypes()
}
}
// SAFETY: Only reads World components
unsafe impl<'a> ReadOnlySystemParam for &'a Components {}
// SAFETY: no component value access
unsafe impl<'a> SystemParam for &'a Components {
type State = ();
type Item<'w, 's> = &'w Components;
fn init_state(_world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {}
#[inline]
unsafe fn get_param<'w, 's>(
_state: &'s mut Self::State,
_system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
_change_tick: Tick,
) -> Self::Item<'w, 's> {
world.components()
}
}
// SAFETY: Only reads World entities
unsafe impl<'a> ReadOnlySystemParam for &'a Entities {}
// SAFETY: no component value access
unsafe impl<'a> SystemParam for &'a Entities {
type State = ();
type Item<'w, 's> = &'w Entities;
fn init_state(_world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {}
#[inline]
unsafe fn get_param<'w, 's>(
_state: &'s mut Self::State,
_system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
_change_tick: Tick,
) -> Self::Item<'w, 's> {
world.entities()
}
}
// SAFETY: Only reads World bundles
unsafe impl<'a> ReadOnlySystemParam for &'a Bundles {}
// SAFETY: no component value access
unsafe impl<'a> SystemParam for &'a Bundles {
type State = ();
type Item<'w, 's> = &'w Bundles;
fn init_state(_world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {}
#[inline]
unsafe fn get_param<'w, 's>(
_state: &'s mut Self::State,
_system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
_change_tick: Tick,
) -> Self::Item<'w, 's> {
world.bundles()
}
}
/// A [`SystemParam`] that reads the previous and current change ticks of the system.
///
/// A system's change ticks are updated each time it runs:
/// - `last_run` copies the previous value of `change_tick`
/// - `this_run` copies the current value of [`World::read_change_tick`]
///
/// Component change ticks that are more recent than `last_run` will be detected by the system.
/// Those can be read by calling [`last_changed`](crate::change_detection::DetectChanges::last_changed)
/// on a [`Mut<T>`](crate::change_detection::Mut) or [`ResMut<T>`](ResMut).
#[derive(Debug)]
pub struct SystemChangeTick {
last_run: Tick,
this_run: Tick,
}
impl SystemChangeTick {
/// Returns the current [`World`] change tick seen by the system.
#[inline]
pub fn this_run(&self) -> Tick {
self.this_run
}
/// Returns the [`World`] change tick seen by the system the previous time it ran.
#[inline]
pub fn last_run(&self) -> Tick {
self.last_run
}
}
// SAFETY: Only reads internal system state
unsafe impl ReadOnlySystemParam for SystemChangeTick {}
// SAFETY: `SystemChangeTick` doesn't require any world access
unsafe impl SystemParam for SystemChangeTick {
type State = ();
type Item<'w, 's> = SystemChangeTick;
fn init_state(_world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {}
unsafe fn get_param<'w, 's>(
_state: &'s mut Self::State,
system_meta: &SystemMeta,
_world: UnsafeWorldCell<'w>,
change_tick: Tick,
) -> Self::Item<'w, 's> {
SystemChangeTick {
last_run: system_meta.last_run,
this_run: change_tick,
}
}
}
macro_rules! impl_system_param_tuple {
($($param: ident),*) => {
// SAFETY: tuple consists only of ReadOnlySystemParams
unsafe impl<$($param: ReadOnlySystemParam),*> ReadOnlySystemParam for ($($param,)*) {}
// SAFETY: implementors of each `SystemParam` in the tuple have validated their impls
#[allow(clippy::undocumented_unsafe_blocks)] // false positive by clippy
#[allow(non_snake_case)]
unsafe impl<$($param: SystemParam),*> SystemParam for ($($param,)*) {
type State = ($($param::State,)*);
type Item<'w, 's> = ($($param::Item::<'w, 's>,)*);
#[inline]
fn init_state(_world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {
(($($param::init_state(_world, _system_meta),)*))
}
#[inline]
#[allow(unused_unsafe)]
unsafe fn new_archetype(($($param,)*): &mut Self::State, _archetype: &Archetype, _system_meta: &mut SystemMeta) {
// SAFETY: The caller ensures that `archetype` is from the World the state was initialized from in `init_state`.
unsafe { $($param::new_archetype($param, _archetype, _system_meta);)* }
}
#[inline]
fn apply(($($param,)*): &mut Self::State, _system_meta: &SystemMeta, _world: &mut World) {
$($param::apply($param, _system_meta, _world);)*
}
#[inline]
fn queue(($($param,)*): &mut Self::State, _system_meta: &SystemMeta, mut _world: DeferredWorld) {
$($param::queue($param, _system_meta, _world.reborrow());)*
}
#[inline]
#[allow(clippy::unused_unit)]
unsafe fn get_param<'w, 's>(
state: &'s mut Self::State,
_system_meta: &SystemMeta,
_world: UnsafeWorldCell<'w>,
_change_tick: Tick,
) -> Self::Item<'w, 's> {
let ($($param,)*) = state;
($($param::get_param($param, _system_meta, _world, _change_tick),)*)
}
}
};
}
all_tuples!(impl_system_param_tuple, 0, 16, P);
/// Contains type aliases for built-in [`SystemParam`]s with `'static` lifetimes.
/// This makes it more convenient to refer to these types in contexts where
/// explicit lifetime annotations are required.
///
/// Note that this is entirely safe and tracks lifetimes correctly.
/// This purely exists for convenience.
///
/// You can't instantiate a static `SystemParam`, you'll always end up with
/// `Res<'w, T>`, `ResMut<'w, T>` or `&'w T` bound to the lifetime of the provided
/// `&'w World`.
///
/// [`SystemParam`]: super::SystemParam
pub mod lifetimeless {
/// A [`Query`](super::Query) with `'static` lifetimes.
pub type SQuery<D, F = ()> = super::Query<'static, 'static, D, F>;
/// A shorthand for writing `&'static T`.
pub type Read<T> = &'static T;
/// A shorthand for writing `&'static mut T`.
pub type Write<T> = &'static mut T;
/// A [`Res`](super::Res) with `'static` lifetimes.
pub type SRes<T> = super::Res<'static, T>;
/// A [`ResMut`](super::ResMut) with `'static` lifetimes.
pub type SResMut<T> = super::ResMut<'static, T>;
/// [`Commands`](crate::system::Commands) with `'static` lifetimes.
pub type SCommands = crate::system::Commands<'static, 'static>;
}
/// A helper for using system parameters in generic contexts
///
/// This type is a [`SystemParam`] adapter which always has
/// `Self::State::Item == Self` (ignoring lifetimes for brevity),
/// no matter the argument [`SystemParam`] (`P`) (other than
/// that `P` must be `'static`)
///
/// This makes it useful for having arbitrary [`SystemParam`] type arguments
/// to function systems, or for generic types using the [`derive@SystemParam`]
/// derive:
///
/// ```
/// # use bevy_ecs::prelude::*;
/// use bevy_ecs::system::{SystemParam, StaticSystemParam};
/// #[derive(SystemParam)]
/// struct GenericParam<'w,'s, T: SystemParam + 'static> {
/// field: StaticSystemParam<'w, 's, T>,
/// }
/// fn do_thing_generically<T: SystemParam + 'static>(t: StaticSystemParam<T>) {}
///
/// fn check_always_is_system<T: SystemParam + 'static>(){
/// bevy_ecs::system::assert_is_system(do_thing_generically::<T>);
/// }
/// ```
/// Note that in a real case you'd generally want
/// additional bounds on `P`, for your use of the parameter
/// to have a reason to be generic.
///
/// For example, using this would allow a type to be generic over
/// whether a resource is accessed mutably or not, with
/// impls being bounded on [`P: Deref<Target=MyType>`](Deref), and
/// [`P: DerefMut<Target=MyType>`](DerefMut) depending on whether the
/// method requires mutable access or not.
///
/// The method which doesn't use this type will not compile:
/// ```compile_fail
/// # use bevy_ecs::prelude::*;
/// # use bevy_ecs::system::{SystemParam, StaticSystemParam};
///
/// fn do_thing_generically<T: SystemParam + 'static>(t: T) {}
///
/// #[derive(SystemParam)]
/// struct GenericParam<'w, 's, T: SystemParam> {
/// field: T,
/// // Use the lifetimes in this type, or they will be unbound.
/// phantom: core::marker::PhantomData<&'w &'s ()>
/// }
/// # fn check_always_is_system<T: SystemParam + 'static>(){
/// # bevy_ecs::system::assert_is_system(do_thing_generically::<T>);
/// # }
/// ```
///
pub struct StaticSystemParam<'w, 's, P: SystemParam>(SystemParamItem<'w, 's, P>);
impl<'w, 's, P: SystemParam> Deref for StaticSystemParam<'w, 's, P> {
type Target = SystemParamItem<'w, 's, P>;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl<'w, 's, P: SystemParam> DerefMut for StaticSystemParam<'w, 's, P> {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.0
}
}
impl<'w, 's, P: SystemParam> StaticSystemParam<'w, 's, P> {
/// Get the value of the parameter
pub fn into_inner(self) -> SystemParamItem<'w, 's, P> {
self.0
}
}
// SAFETY: This doesn't add any more reads, and the delegated fetch confirms it
unsafe impl<'w, 's, P: ReadOnlySystemParam + 'static> ReadOnlySystemParam
for StaticSystemParam<'w, 's, P>
{
}
// SAFETY: all methods are just delegated to `P`'s `SystemParam` implementation
unsafe impl<P: SystemParam + 'static> SystemParam for StaticSystemParam<'_, '_, P> {
type State = P::State;
type Item<'world, 'state> = StaticSystemParam<'world, 'state, P>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
P::init_state(world, system_meta)
}
unsafe fn new_archetype(
state: &mut Self::State,
archetype: &Archetype,
system_meta: &mut SystemMeta,
) {
// SAFETY: The caller guarantees that the provided `archetype` matches the World used to initialize `state`.
unsafe { P::new_archetype(state, archetype, system_meta) };
}
fn apply(state: &mut Self::State, system_meta: &SystemMeta, world: &mut World) {
P::apply(state, system_meta, world);
}
fn queue(state: &mut Self::State, system_meta: &SystemMeta, world: DeferredWorld) {
P::queue(state, system_meta, world);
}
unsafe fn get_param<'world, 'state>(
state: &'state mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'world>,
change_tick: Tick,
) -> Self::Item<'world, 'state> {
// SAFETY: Defer to the safety of P::SystemParam
StaticSystemParam(unsafe { P::get_param(state, system_meta, world, change_tick) })
}
}
// SAFETY: No world access.
unsafe impl<T: ?Sized> SystemParam for PhantomData<T> {
type State = ();
type Item<'world, 'state> = Self;
fn init_state(_world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {}
unsafe fn get_param<'world, 'state>(
_state: &'state mut Self::State,
_system_meta: &SystemMeta,
_world: UnsafeWorldCell<'world>,
_change_tick: Tick,
) -> Self::Item<'world, 'state> {
PhantomData
}
}
// SAFETY: No world access.
unsafe impl<T: ?Sized> ReadOnlySystemParam for PhantomData<T> {}
#[cfg(test)]
mod tests {
use super::*;
use crate::{
self as bevy_ecs, // Necessary for the `SystemParam` Derive when used inside `bevy_ecs`.
system::assert_is_system,
};
use std::cell::RefCell;
// Compile test for https://github.com/bevyengine/bevy/pull/2838.
#[test]
fn system_param_generic_bounds() {
#[derive(SystemParam)]
pub struct SpecialQuery<
'w,
's,
D: QueryData + Send + Sync + 'static,
F: QueryFilter + Send + Sync + 'static = (),
> {
_query: Query<'w, 's, D, F>,
}
fn my_system(_: SpecialQuery<(), ()>) {}
assert_is_system(my_system);
}
// Compile tests for https://github.com/bevyengine/bevy/pull/6694.
#[test]
fn system_param_flexibility() {
#[derive(SystemParam)]
pub struct SpecialRes<'w, T: Resource> {
_res: Res<'w, T>,
}
#[derive(SystemParam)]
pub struct SpecialLocal<'s, T: FromWorld + Send + 'static> {
_local: Local<'s, T>,
}
#[derive(Resource)]
struct R;
fn my_system(_: SpecialRes<R>, _: SpecialLocal<u32>) {}
assert_is_system(my_system);
}
#[derive(Resource)]
pub struct R<const I: usize>;
// Compile test for https://github.com/bevyengine/bevy/pull/7001.
#[test]
fn system_param_const_generics() {
#[allow(dead_code)]
#[derive(SystemParam)]
pub struct ConstGenericParam<'w, const I: usize>(Res<'w, R<I>>);
fn my_system(_: ConstGenericParam<0>, _: ConstGenericParam<1000>) {}
assert_is_system(my_system);
}
// Compile test for https://github.com/bevyengine/bevy/pull/6867.
#[test]
fn system_param_field_limit() {
#[derive(SystemParam)]
pub struct LongParam<'w> {
// Each field should be a distinct type so there will
// be an error if the derive messes up the field order.
_r0: Res<'w, R<0>>,
_r1: Res<'w, R<1>>,
_r2: Res<'w, R<2>>,
_r3: Res<'w, R<3>>,
_r4: Res<'w, R<4>>,
_r5: Res<'w, R<5>>,
_r6: Res<'w, R<6>>,
_r7: Res<'w, R<7>>,
_r8: Res<'w, R<8>>,
_r9: Res<'w, R<9>>,
_r10: Res<'w, R<10>>,
_r11: Res<'w, R<11>>,
_r12: Res<'w, R<12>>,
_r13: Res<'w, R<13>>,
_r14: Res<'w, R<14>>,
_r15: Res<'w, R<15>>,
_r16: Res<'w, R<16>>,
}
fn long_system(_: LongParam) {}
assert_is_system(long_system);
}
// Compile test for https://github.com/bevyengine/bevy/pull/6919.
// Regression test for https://github.com/bevyengine/bevy/issues/7447.
#[test]
fn system_param_phantom_data() {
#[derive(SystemParam)]
struct PhantomParam<'w, T: Resource, Marker: 'static> {
_foo: Res<'w, T>,
marker: PhantomData<&'w Marker>,
}
fn my_system(_: PhantomParam<R<0>, ()>) {}
assert_is_system(my_system);
}
// Compile tests for https://github.com/bevyengine/bevy/pull/6957.
#[test]
fn system_param_struct_variants() {
#[derive(SystemParam)]
pub struct UnitParam;
#[allow(dead_code)]
#[derive(SystemParam)]
pub struct TupleParam<'w, 's, R: Resource, L: FromWorld + Send + 'static>(
Res<'w, R>,
Local<'s, L>,
);
fn my_system(_: UnitParam, _: TupleParam<R<0>, u32>) {}
assert_is_system(my_system);
}
// Regression test for https://github.com/bevyengine/bevy/issues/4200.
#[test]
fn system_param_private_fields() {
#[derive(Resource)]
struct PrivateResource;
#[allow(dead_code)]
#[derive(SystemParam)]
pub struct EncapsulatedParam<'w>(Res<'w, PrivateResource>);
fn my_system(_: EncapsulatedParam) {}
assert_is_system(my_system);
}
// Regression test for https://github.com/bevyengine/bevy/issues/7103.
#[test]
fn system_param_where_clause() {
#[derive(SystemParam)]
pub struct WhereParam<'w, 's, D>
where
D: 'static + QueryData,
{
_q: Query<'w, 's, D, ()>,
}
fn my_system(_: WhereParam<()>) {}
assert_is_system(my_system);
}
// Regression test for https://github.com/bevyengine/bevy/issues/1727.
#[test]
fn system_param_name_collision() {
#[derive(Resource)]
pub struct FetchState;
#[derive(SystemParam)]
pub struct Collide<'w> {
_x: Res<'w, FetchState>,
}
fn my_system(_: Collide) {}
assert_is_system(my_system);
}
// Regression test for https://github.com/bevyengine/bevy/issues/8192.
#[test]
fn system_param_invariant_lifetime() {
#[derive(SystemParam)]
pub struct InvariantParam<'w, 's> {
_set: ParamSet<'w, 's, (Query<'w, 's, ()>,)>,
}
fn my_system(_: InvariantParam) {}
assert_is_system(my_system);
}
// Compile test for https://github.com/bevyengine/bevy/pull/9589.
#[test]
fn non_sync_local() {
fn non_sync_system(cell: Local<RefCell<u8>>) {
assert_eq!(*cell.borrow(), 0);
}
let mut world = World::new();
let mut schedule = crate::schedule::Schedule::default();
schedule.add_systems(non_sync_system);
schedule.run(&mut world);
}
// Regression test for https://github.com/bevyengine/bevy/issues/10207.
#[test]
fn param_set_non_send_first() {
fn non_send_param_set(mut p: ParamSet<(NonSend<*mut u8>, ())>) {
let _ = p.p0();
p.p1();
}
let mut world = World::new();
world.insert_non_send_resource(std::ptr::null_mut::<u8>());
let mut schedule = crate::schedule::Schedule::default();
schedule.add_systems((non_send_param_set, non_send_param_set, non_send_param_set));
schedule.run(&mut world);
}
// Regression test for https://github.com/bevyengine/bevy/issues/10207.
#[test]
fn param_set_non_send_second() {
fn non_send_param_set(mut p: ParamSet<((), NonSendMut<*mut u8>)>) {
p.p0();
let _ = p.p1();
}
let mut world = World::new();
world.insert_non_send_resource(std::ptr::null_mut::<u8>());
let mut schedule = crate::schedule::Schedule::default();
schedule.add_systems((non_send_param_set, non_send_param_set, non_send_param_set));
schedule.run(&mut world);
}
}