+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! A typesafe bitmask flag generator.
+
+/// The `bitflags!` macro generates a `struct` that holds a set of C-style
+/// bitmask flags. It is useful for creating typesafe wrappers for C APIs.
+///
+/// The flags should only be defined for integer types, otherwise unexpected
+/// type errors may occur at compile time.
+///
+/// # Example
+///
+/// ```{.rust}
+/// #[macro_use]
+/// extern crate bitflags;
+///
+/// bitflags! {
+///     flags Flags: u32 {
+///         const FLAG_A       = 0b00000001,
+///         const FLAG_B       = 0b00000010,
+///         const FLAG_C       = 0b00000100,
+///         const FLAG_ABC     = FLAG_A.bits
+///                            | FLAG_B.bits
+///                            | FLAG_C.bits,
+///     }
+/// }
+///
+/// fn main() {
+///     let e1 = FLAG_A | FLAG_C;
+///     let e2 = FLAG_B | FLAG_C;
+///     assert!((e1 | e2) == FLAG_ABC);   // union
+///     assert!((e1 & e2) == FLAG_C);     // intersection
+///     assert!((e1 - e2) == FLAG_A);     // set difference
+///     assert!(!e2 == FLAG_A);           // set complement
+/// }
+/// ```
+///
+/// The generated `struct`s can also be extended with type and trait
+/// implementations:
+///
+/// ```{.rust}
+/// #[macro_use]
+/// extern crate bitflags;
+///
+/// use std::fmt;
+///
+/// bitflags! {
+///     flags Flags: u32 {
+///         const FLAG_A   = 0b00000001,
+///         const FLAG_B   = 0b00000010,
+///     }
+/// }
+///
+/// impl Flags {
+///     pub fn clear(&mut self) {
+///         self.bits = 0;  // The `bits` field can be accessed from within the
+///                         // same module where the `bitflags!` macro was invoked.
+///     }
+/// }
+///
+/// impl fmt::Display for Flags {
+///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+///         write!(f, "hi!")
+///     }
+/// }
+///
+/// fn main() {
+///     let mut flags = FLAG_A | FLAG_B;
+///     flags.clear();
+///     assert!(flags.is_empty());
+///     assert_eq!(format!("{}", flags), "hi!");
+///     assert_eq!(format!("{:?}", FLAG_A | FLAG_B), "Flags { bits: 0b11 }");
+///     assert_eq!(format!("{:?}", FLAG_B), "Flags { bits: 0b10 }");
+/// }
+/// ```
+///
+/// # Attributes
+///
+/// Attributes can be attached to the generated `struct` by placing them
+/// before the `flags` keyword.
+///
+/// # Derived traits
+///
+/// The `PartialEq` and `Clone` traits are automatically derived for the
+/// `struct` using the `deriving` attribute. Additional traits can be derived by
+/// providing an explicit `deriving` attribute on `flags`. The `Debug` trait is
+/// also implemented by displaying the bits value of the internal struct.
+///
+/// # Operators
+///
+/// The following operator traits are implemented for the generated `struct`:
+///
+/// - `BitOr`: union
+/// - `BitAnd`: intersection
+/// - `BitXor`: toggle
+/// - `Sub`: set difference
+/// - `Not`: set complement
+///
+/// # Methods
+///
+/// The following methods are defined for the generated `struct`:
+///
+/// - `empty`: an empty set of flags
+/// - `all`: the set of all flags
+/// - `bits`: the raw value of the flags currently stored
+/// - `from_bits`: convert from underlying bit representation, unless that
+///                representation contains bits that do not correspond to a flag
+/// - `from_bits_truncate`: convert from underlying bit representation, dropping
+///                         any bits that do not correspond to flags
+/// - `is_empty`: `true` if no flags are currently stored
+/// - `is_all`: `true` if all flags are currently set
+/// - `intersects`: `true` if there are flags common to both `self` and `other`
+/// - `contains`: `true` all of the flags in `other` are contained within `self`
+/// - `insert`: inserts the specified flags in-place
+/// - `remove`: removes the specified flags in-place
+/// - `toggle`: the specified flags will be inserted if not present, and removed
+///             if they are.
+#[macro_export]
+macro_rules! bitflags {
+    ($(#[$attr:meta])* flags $BitFlags:ident: $T:ty {
+        $($(#[$Flag_attr:meta])* const $Flag:ident = $value:expr),+
+    }) => {
+        #[derive(Copy, PartialEq, Eq, Clone, PartialOrd, Ord, Hash)]
+        $(#[$attr])*
+        pub struct $BitFlags {
+            bits: $T,
+        }
+
+        $($(#[$Flag_attr])* pub const $Flag: $BitFlags = $BitFlags { bits: $value };)+
+
+        impl ::std::fmt::Debug for $BitFlags {
+            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                let out = format!("{} {{ bits: {:#b} }}",
+                                  stringify!($BitFlags),
+                                  self.bits);
+                f.write_str(&out[..])
+            }
+        }
+
+        impl $BitFlags {
+            /// Returns an empty set of flags.
+            #[inline]
+            pub fn empty() -> $BitFlags {
+                $BitFlags { bits: 0 }
+            }
+
+            /// Returns the set containing all flags.
+            #[inline]
+            pub fn all() -> $BitFlags {
+                $BitFlags { bits: $($value)|+ }
+            }
+
+            /// Returns the raw value of the flags currently stored.
+            #[inline]
+            pub fn bits(&self) -> $T {
+                self.bits
+            }
+
+            /// Convert from underlying bit representation, unless that
+            /// representation contains bits that do not correspond to a flag.
+            #[inline]
+            pub fn from_bits(bits: $T) -> ::std::option::Option<$BitFlags> {
+                if (bits & !$BitFlags::all().bits()) != 0 {
+                    ::std::option::Option::None
+                } else {
+                    ::std::option::Option::Some($BitFlags { bits: bits })
+                }
+            }
+
+            /// Convert from underlying bit representation, dropping any bits
+            /// that do not correspond to flags.
+            #[inline]
+            pub fn from_bits_truncate(bits: $T) -> $BitFlags {
+                $BitFlags { bits: bits } & $BitFlags::all()
+            }
+
+            /// Returns `true` if no flags are currently stored.
+            #[inline]
+            pub fn is_empty(&self) -> bool {
+                *self == $BitFlags::empty()
+            }
+
+            /// Returns `true` if all flags are currently set.
+            #[inline]
+            pub fn is_all(&self) -> bool {
+                *self == $BitFlags::all()
+            }
+
+            /// Returns `true` if there are flags common to both `self` and `other`.
+            #[inline]
+            pub fn intersects(&self, other: $BitFlags) -> bool {
+                !(*self & other).is_empty()
+            }
+
+            /// Returns `true` all of the flags in `other` are contained within `self`.
+            #[inline]
+            pub fn contains(&self, other: $BitFlags) -> bool {
+                (*self & other) == other
+            }
+
+            /// Inserts the specified flags in-place.
+            #[inline]
+            pub fn insert(&mut self, other: $BitFlags) {
+                self.bits |= other.bits;
+            }
+
+            /// Removes the specified flags in-place.
+            #[inline]
+            pub fn remove(&mut self, other: $BitFlags) {
+                self.bits &= !other.bits;
+            }
+
+            /// Toggles the specified flags in-place.
+            #[inline]
+            pub fn toggle(&mut self, other: $BitFlags) {
+                self.bits ^= other.bits;
+            }
+        }
+
+        impl ::std::ops::BitOr for $BitFlags {
+            type Output = $BitFlags;
+
+            /// Returns the union of the two sets of flags.
+            #[inline]
+            fn bitor(self, other: $BitFlags) -> $BitFlags {
+                $BitFlags { bits: self.bits | other.bits }
+            }
+        }
+
+        impl ::std::ops::BitXor for $BitFlags {
+            type Output = $BitFlags;
+
+            /// Returns the left flags, but with all the right flags toggled.
+            #[inline]
+            fn bitxor(self, other: $BitFlags) -> $BitFlags {
+                $BitFlags { bits: self.bits ^ other.bits }
+            }
+        }
+
+        impl ::std::ops::BitAnd for $BitFlags {
+            type Output = $BitFlags;
+
+            /// Returns the intersection between the two sets of flags.
+            #[inline]
+            fn bitand(self, other: $BitFlags) -> $BitFlags {
+                $BitFlags { bits: self.bits & other.bits }
+            }
+        }
+
+        impl ::std::ops::Sub for $BitFlags {
+            type Output = $BitFlags;
+
+            /// Returns the set difference of the two sets of flags.
+            #[inline]
+            fn sub(self, other: $BitFlags) -> $BitFlags {
+                $BitFlags { bits: self.bits & !other.bits }
+            }
+        }
+
+        impl ::std::ops::Not for $BitFlags {
+            type Output = $BitFlags;
+
+            /// Returns the complement of this set of flags.
+            #[inline]
+            fn not(self) -> $BitFlags {
+                $BitFlags { bits: !self.bits } & $BitFlags::all()
+            }
+        }
+    };
+    ($(#[$attr:meta])* flags $BitFlags:ident: $T:ty {
+        $($(#[$Flag_attr:meta])* const $Flag:ident = $value:expr),+,
+    }) => {
+        bitflags! {
+            $(#[$attr])*
+            flags $BitFlags: $T {
+                $($(#[$Flag_attr])* const $Flag = $value),+
+            }
+        }
+    };
+}
+
+#[cfg(test)]
+#[allow(non_upper_case_globals, dead_code)]
+mod tests {
+    use std::hash::{SipHasher, Hash, Hasher};
+
+    bitflags! {
+        #[doc = "> The first principle is that you must not fool yourself — and"]
+        #[doc = "> you are the easiest person to fool."]
+        #[doc = "> "]
+        #[doc = "> - Richard Feynman"]
+        flags Flags: u32 {
+            const FlagA       = 0b00000001,
+            #[doc = "<pcwalton> macros are way better at generating code than trans is"]
+            const FlagB       = 0b00000010,
+            const FlagC       = 0b00000100,
+            #[doc = "* cmr bed"]
+            #[doc = "* strcat table"]
+            #[doc = "<strcat> wait what?"]
+            const FlagABC     = FlagA.bits
+                               | FlagB.bits
+                               | FlagC.bits,
+        }
+    }
+
+    bitflags! {
+        flags _CfgFlags: u32 {
+            #[cfg(windows)]
+            const _CfgA = 0b01,
+            #[cfg(unix)]
+            const _CfgB = 0b01,
+        }
+    }
+
+    bitflags! {
+        flags AnotherSetOfFlags: i8 {
+            const AnotherFlag = -1_i8,
+        }
+    }
+
+    #[test]
+    fn test_bits(){
+        assert_eq!(Flags::empty().bits(), 0b00000000);
+        assert_eq!(FlagA.bits(), 0b00000001);
+        assert_eq!(FlagABC.bits(), 0b00000111);
+
+        assert_eq!(AnotherSetOfFlags::empty().bits(), 0b00);
+        assert_eq!(AnotherFlag.bits(), !0_i8);
+    }
+
+    #[test]
+    fn test_from_bits() {
+        assert!(Flags::from_bits(0) == Some(Flags::empty()));
+        assert!(Flags::from_bits(0b1) == Some(FlagA));
+        assert!(Flags::from_bits(0b10) == Some(FlagB));
+        assert!(Flags::from_bits(0b11) == Some(FlagA | FlagB));
+        assert!(Flags::from_bits(0b1000) == None);
+
+        assert!(AnotherSetOfFlags::from_bits(!0_i8) == Some(AnotherFlag));
+    }
+
+    #[test]
+    fn test_from_bits_truncate() {
+        assert!(Flags::from_bits_truncate(0) == Flags::empty());
+        assert!(Flags::from_bits_truncate(0b1) == FlagA);
+        assert!(Flags::from_bits_truncate(0b10) == FlagB);
+        assert!(Flags::from_bits_truncate(0b11) == (FlagA | FlagB));
+        assert!(Flags::from_bits_truncate(0b1000) == Flags::empty());
+        assert!(Flags::from_bits_truncate(0b1001) == FlagA);
+
+        assert!(AnotherSetOfFlags::from_bits_truncate(0_i8) == AnotherSetOfFlags::empty());
+    }
+
+    #[test]
+    fn test_is_empty(){
+        assert!(Flags::empty().is_empty());
+        assert!(!FlagA.is_empty());
+        assert!(!FlagABC.is_empty());
+
+        assert!(!AnotherFlag.is_empty());
+    }
+
+    #[test]
+    fn test_is_all() {
+        assert!(Flags::all().is_all());
+        assert!(!FlagA.is_all());
+        assert!(FlagABC.is_all());
+
+        assert!(AnotherFlag.is_all());
+    }
+
+    #[test]
+    fn test_two_empties_do_not_intersect() {
+        let e1 = Flags::empty();
+        let e2 = Flags::empty();
+        assert!(!e1.intersects(e2));
+
+        assert!(AnotherFlag.intersects(AnotherFlag));
+    }
+
+    #[test]
+    fn test_empty_does_not_intersect_with_full() {
+        let e1 = Flags::empty();
+        let e2 = FlagABC;
+        assert!(!e1.intersects(e2));
+    }
+
+    #[test]
+    fn test_disjoint_intersects() {
+        let e1 = FlagA;
+        let e2 = FlagB;
+        assert!(!e1.intersects(e2));
+    }
+
+    #[test]
+    fn test_overlapping_intersects() {
+        let e1 = FlagA;
+        let e2 = FlagA | FlagB;
+        assert!(e1.intersects(e2));
+    }
+
+    #[test]
+    fn test_contains() {
+        let e1 = FlagA;
+        let e2 = FlagA | FlagB;
+        assert!(!e1.contains(e2));
+        assert!(e2.contains(e1));
+        assert!(FlagABC.contains(e2));
+
+        assert!(AnotherFlag.contains(AnotherFlag));
+    }
+
+    #[test]
+    fn test_insert(){
+        let mut e1 = FlagA;
+        let e2 = FlagA | FlagB;
+        e1.insert(e2);
+        assert!(e1 == e2);
+
+        let mut e3 = AnotherSetOfFlags::empty();
+        e3.insert(AnotherFlag);
+        assert!(e3 == AnotherFlag);
+    }
+
+    #[test]
+    fn test_remove(){
+        let mut e1 = FlagA | FlagB;
+        let e2 = FlagA | FlagC;
+        e1.remove(e2);
+        assert!(e1 == FlagB);
+
+        let mut e3 = AnotherFlag;
+        e3.remove(AnotherFlag);
+        assert!(e3 == AnotherSetOfFlags::empty());
+    }
+
+    #[test]
+    fn test_operators() {
+        let e1 = FlagA | FlagC;
+        let e2 = FlagB | FlagC;
+        assert!((e1 | e2) == FlagABC);     // union
+        assert!((e1 & e2) == FlagC);       // intersection
+        assert!((e1 - e2) == FlagA);       // set difference
+        assert!(!e2 == FlagA);             // set complement
+        assert!(e1 ^ e2 == FlagA | FlagB); // toggle
+        let mut e3 = e1;
+        e3.toggle(e2);
+        assert!(e3 == FlagA | FlagB);
+
+        let mut m4 = AnotherSetOfFlags::empty();
+        m4.toggle(AnotherSetOfFlags::empty());
+        assert!(m4 == AnotherSetOfFlags::empty());
+    }
+
+    #[test]
+    fn test_lt() {
+        let mut a = Flags::empty();
+        let mut b = Flags::empty();
+
+        assert!(!(a < b) && !(b < a));
+        b = FlagB;
+        assert!(a < b);
+        a = FlagC;
+        assert!(!(a < b) && b < a);
+        b = FlagC | FlagB;
+        assert!(a < b);
+    }
+
+    #[test]
+    fn test_ord() {
+        let mut a = Flags::empty();
+        let mut b = Flags::empty();
+
+        assert!(a <= b && a >= b);
+        a = FlagA;
+        assert!(a > b && a >= b);
+        assert!(b < a && b <= a);
+        b = FlagB;
+        assert!(b > a && b >= a);
+        assert!(a < b && a <= b);
+    }
+
+    fn hash<T: Hash>(t: &T) -> u64 {
+        let mut s = SipHasher::new_with_keys(0, 0);
+        t.hash(&mut s);
+        s.finish()
+    }
+
+    #[test]
+    fn test_hash() {
+        let mut x = Flags::empty();
+        let mut y = Flags::empty();
+        assert!(hash(&x) == hash(&y));
+        x = Flags::all();
+        y = FlagABC;
+        assert!(hash(&x) == hash(&y));
+    }
+
+    #[test]
+    fn test_debug() {
+        assert_eq!(format!("{:?}", FlagA | FlagB), "Flags { bits: 0b11 }");
+        assert_eq!(format!("{:?}", FlagABC), "Flags { bits: 0b111 }");
+    }
+}
+

+

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