1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
14 //! A typesafe bitmask flag generator.
16 /// The `bitflags!` macro generates a `struct` that holds a set of C-style
17 /// bitmask flags. It is useful for creating typesafe wrappers for C APIs.
19 /// The flags should only be defined for integer types, otherwise unexpected
20 /// type errors may occur at compile time.
26 /// flags Flags: u32 {
27 /// const FLAG_A = 0b00000001,
28 /// const FLAG_B = 0b00000010,
29 /// const FLAG_C = 0b00000100,
30 /// const FLAG_ABC = FLAG_A.bits
37 /// let e1 = FLAG_A | FLAG_C;
38 /// let e2 = FLAG_B | FLAG_C;
39 /// assert!((e1 | e2) == FLAG_ABC); // union
40 /// assert!((e1 & e2) == FLAG_C); // intersection
41 /// assert!((e1 - e2) == FLAG_A); // set difference
42 /// assert!(!e2 == FLAG_A); // set complement
46 /// The generated `struct`s can also be extended with type and trait implementations:
52 /// flags Flags: u32 {
53 /// const FLAG_A = 0b00000001,
54 /// const FLAG_B = 0b00000010,
59 /// pub fn clear(&mut self) {
60 /// self.bits = 0; // The `bits` field can be accessed from within the
61 /// // same module where the `bitflags!` macro was invoked.
65 /// impl fmt::Show for Flags {
66 /// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
72 /// let mut flags = FLAG_A | FLAG_B;
74 /// assert!(flags.is_empty());
75 /// assert_eq!(format!("{}", flags).as_slice(), "hi!");
81 /// Attributes can be attached to the generated `struct` by placing them
82 /// before the `flags` keyword.
86 /// The `PartialEq` and `Clone` traits are automatically derived for the `struct` using
87 /// the `deriving` attribute. Additional traits can be derived by providing an
88 /// explicit `deriving` attribute on `flags`.
92 /// The following operator traits are implemented for the generated `struct`:
95 /// - `BitAnd`: intersection
96 /// - `BitXor`: toggle
97 /// - `Sub`: set difference
98 /// - `Not`: set complement
102 /// The following methods are defined for the generated `struct`:
104 /// - `empty`: an empty set of flags
105 /// - `all`: the set of all flags
106 /// - `bits`: the raw value of the flags currently stored
107 /// - `from_bits`: convert from underlying bit representation, unless that
108 /// representation contains bits that do not correspond to a flag
109 /// - `from_bits_truncate`: convert from underlying bit representation, dropping
110 /// any bits that do not correspond to flags
111 /// - `is_empty`: `true` if no flags are currently stored
112 /// - `is_all`: `true` if all flags are currently set
113 /// - `intersects`: `true` if there are flags common to both `self` and `other`
114 /// - `contains`: `true` all of the flags in `other` are contained within `self`
115 /// - `insert`: inserts the specified flags in-place
116 /// - `remove`: removes the specified flags in-place
117 /// - `toggle`: the specified flags will be inserted if not present, and removed
120 macro_rules! bitflags {
121 ($(#[$attr:meta])* flags $BitFlags:ident: $T:ty {
122 $($(#[$Flag_attr:meta])* const $Flag:ident = $value:expr),+
124 #[deriving(Copy, PartialEq, Eq, Clone, PartialOrd, Ord, Hash)]
126 pub struct $BitFlags {
130 $($(#[$Flag_attr])* pub const $Flag: $BitFlags = $BitFlags { bits: $value };)+
133 /// Returns an empty set of flags.
135 pub fn empty() -> $BitFlags {
136 $BitFlags { bits: 0 }
139 /// Returns the set containing all flags.
141 pub fn all() -> $BitFlags {
142 $BitFlags { bits: $($value)|+ }
145 /// Returns the raw value of the flags currently stored.
147 pub fn bits(&self) -> $T {
151 /// Convert from underlying bit representation, unless that
152 /// representation contains bits that do not correspond to a flag.
154 pub fn from_bits(bits: $T) -> ::std::option::Option<$BitFlags> {
155 if (bits & !$BitFlags::all().bits()) != 0 {
156 ::std::option::Option::None
158 ::std::option::Option::Some($BitFlags { bits: bits })
162 /// Convert from underlying bit representation, dropping any bits
163 /// that do not correspond to flags.
165 pub fn from_bits_truncate(bits: $T) -> $BitFlags {
166 $BitFlags { bits: bits } & $BitFlags::all()
169 /// Returns `true` if no flags are currently stored.
171 pub fn is_empty(&self) -> bool {
172 *self == $BitFlags::empty()
175 /// Returns `true` if all flags are currently set.
177 pub fn is_all(&self) -> bool {
178 *self == $BitFlags::all()
181 /// Returns `true` if there are flags common to both `self` and `other`.
183 pub fn intersects(&self, other: $BitFlags) -> bool {
184 !(*self & other).is_empty()
187 /// Returns `true` all of the flags in `other` are contained within `self`.
189 pub fn contains(&self, other: $BitFlags) -> bool {
190 (*self & other) == other
193 /// Inserts the specified flags in-place.
195 pub fn insert(&mut self, other: $BitFlags) {
196 self.bits |= other.bits;
199 /// Removes the specified flags in-place.
201 pub fn remove(&mut self, other: $BitFlags) {
202 self.bits &= !other.bits;
205 /// Toggles the specified flags in-place.
207 pub fn toggle(&mut self, other: $BitFlags) {
208 self.bits ^= other.bits;
212 impl ::std::ops::BitOr<$BitFlags, $BitFlags> for $BitFlags {
213 /// Returns the union of the two sets of flags.
215 fn bitor(self, other: $BitFlags) -> $BitFlags {
216 $BitFlags { bits: self.bits | other.bits }
220 impl ::std::ops::BitXor<$BitFlags, $BitFlags> for $BitFlags {
221 /// Returns the left flags, but with all the right flags toggled.
223 fn bitxor(self, other: $BitFlags) -> $BitFlags {
224 $BitFlags { bits: self.bits ^ other.bits }
228 impl ::std::ops::BitAnd<$BitFlags, $BitFlags> for $BitFlags {
229 /// Returns the intersection between the two sets of flags.
231 fn bitand(self, other: $BitFlags) -> $BitFlags {
232 $BitFlags { bits: self.bits & other.bits }
236 impl ::std::ops::Sub<$BitFlags, $BitFlags> for $BitFlags {
237 /// Returns the set difference of the two sets of flags.
239 fn sub(self, other: $BitFlags) -> $BitFlags {
240 $BitFlags { bits: self.bits & !other.bits }
244 impl ::std::ops::Not<$BitFlags> for $BitFlags {
245 /// Returns the complement of this set of flags.
247 fn not(self) -> $BitFlags {
248 $BitFlags { bits: !self.bits } & $BitFlags::all()
252 ($(#[$attr:meta])* flags $BitFlags:ident: $T:ty {
253 $($(#[$Flag_attr:meta])* const $Flag:ident = $value:expr),+,
257 flags $BitFlags: $T {
258 $($(#[$Flag_attr])* const $Flag = $value),+
265 #[allow(non_upper_case_globals)]
268 use option::Option::{Some, None};
271 #[doc = "> The first principle is that you must not fool yourself — and"]
272 #[doc = "> you are the easiest person to fool."]
274 #[doc = "> - Richard Feynman"]
276 const FlagA = 0b00000001,
277 #[doc = "<pcwalton> macros are way better at generating code than trans is"]
278 const FlagB = 0b00000010,
279 const FlagC = 0b00000100,
281 #[doc = "* strcat table"]
282 #[doc = "<strcat> wait what?"]
283 const FlagABC = FlagA.bits
290 flags AnotherSetOfFlags: i8 {
291 const AnotherFlag = -1_i8,
297 assert_eq!(Flags::empty().bits(), 0b00000000);
298 assert_eq!(FlagA.bits(), 0b00000001);
299 assert_eq!(FlagABC.bits(), 0b00000111);
301 assert_eq!(AnotherSetOfFlags::empty().bits(), 0b00);
302 assert_eq!(AnotherFlag.bits(), !0_i8);
306 fn test_from_bits() {
307 assert!(Flags::from_bits(0) == Some(Flags::empty()));
308 assert!(Flags::from_bits(0b1) == Some(FlagA));
309 assert!(Flags::from_bits(0b10) == Some(FlagB));
310 assert!(Flags::from_bits(0b11) == Some(FlagA | FlagB));
311 assert!(Flags::from_bits(0b1000) == None);
313 assert!(AnotherSetOfFlags::from_bits(!0_i8) == Some(AnotherFlag));
317 fn test_from_bits_truncate() {
318 assert!(Flags::from_bits_truncate(0) == Flags::empty());
319 assert!(Flags::from_bits_truncate(0b1) == FlagA);
320 assert!(Flags::from_bits_truncate(0b10) == FlagB);
321 assert!(Flags::from_bits_truncate(0b11) == (FlagA | FlagB));
322 assert!(Flags::from_bits_truncate(0b1000) == Flags::empty());
323 assert!(Flags::from_bits_truncate(0b1001) == FlagA);
325 assert!(AnotherSetOfFlags::from_bits_truncate(0_i8) == AnotherSetOfFlags::empty());
330 assert!(Flags::empty().is_empty());
331 assert!(!FlagA.is_empty());
332 assert!(!FlagABC.is_empty());
334 assert!(!AnotherFlag.is_empty());
339 assert!(Flags::all().is_all());
340 assert!(!FlagA.is_all());
341 assert!(FlagABC.is_all());
343 assert!(AnotherFlag.is_all());
347 fn test_two_empties_do_not_intersect() {
348 let e1 = Flags::empty();
349 let e2 = Flags::empty();
350 assert!(!e1.intersects(e2));
352 assert!(AnotherFlag.intersects(AnotherFlag));
356 fn test_empty_does_not_intersect_with_full() {
357 let e1 = Flags::empty();
359 assert!(!e1.intersects(e2));
363 fn test_disjoint_intersects() {
366 assert!(!e1.intersects(e2));
370 fn test_overlapping_intersects() {
372 let e2 = FlagA | FlagB;
373 assert!(e1.intersects(e2));
379 let e2 = FlagA | FlagB;
380 assert!(!e1.contains(e2));
381 assert!(e2.contains(e1));
382 assert!(FlagABC.contains(e2));
384 assert!(AnotherFlag.contains(AnotherFlag));
390 let e2 = FlagA | FlagB;
394 let mut e3 = AnotherSetOfFlags::empty();
395 e3.insert(AnotherFlag);
396 assert!(e3 == AnotherFlag);
401 let mut e1 = FlagA | FlagB;
402 let e2 = FlagA | FlagC;
404 assert!(e1 == FlagB);
406 let mut e3 = AnotherFlag;
407 e3.remove(AnotherFlag);
408 assert!(e3 == AnotherSetOfFlags::empty());
412 fn test_operators() {
413 let e1 = FlagA | FlagC;
414 let e2 = FlagB | FlagC;
415 assert!((e1 | e2) == FlagABC); // union
416 assert!((e1 & e2) == FlagC); // intersection
417 assert!((e1 - e2) == FlagA); // set difference
418 assert!(!e2 == FlagA); // set complement
419 assert!(e1 ^ e2 == FlagA | FlagB); // toggle
422 assert!(e3 == FlagA | FlagB);
424 let mut m4 = AnotherSetOfFlags::empty();
425 m4.toggle(AnotherSetOfFlags::empty());
426 assert!(m4 == AnotherSetOfFlags::empty());
431 let mut a = Flags::empty();
432 let mut b = Flags::empty();
434 assert!(!(a < b) && !(b < a));
438 assert!(!(a < b) && b < a);
445 let mut a = Flags::empty();
446 let mut b = Flags::empty();
448 assert!(a <= b && a >= b);
450 assert!(a > b && a >= b);
451 assert!(b < a && b <= a);
453 assert!(b > a && b >= a);
454 assert!(a < b && a <= b);
459 let mut x = Flags::empty();
460 let mut y = Flags::empty();
461 assert!(hash::hash(&x) == hash::hash(&y));
464 assert!(hash::hash(&x) == hash::hash(&y));