Merge pull request #86 from jcmoyer/flags-trait

Flags trait

src/sdl2/flags.rs

@@ -1,9 +1,11 @@
 // Loosely based on zlib-licensed code from RustAllegro
 //     https://github.com/SiegeLord/RustAllegro
 //
-// Implements efficient, type-safe flags with support for bitwise operators.
+//! Implements efficient, type-safe flags with support for bitwise operators.
 //
-// Usage:
+// The macros defined in this module are for internal usage only.
+//
+// Example:
 //
 // flag_type!(FlagTypeName {
 //     FlagName1 = FlagValue1,
@@ -19,6 +21,22 @@
 
 #![macro_escape]
 
+/// The `Flags` trait is used to define values for flag types where either none
+/// or all of the flags are set.
+pub trait Flags: ::std::ops::Not<Self> {
+    /// Returns a value representing an empty bitset. Implementors should ensure
+    /// this function returns the equivalent of `0` (no bits set) for a flag
+    /// type.
+    fn none() -> Self;
+
+    /// By default, this function will negate the result of `none()`. For sanely
+    /// implemented types, this should be equivalent to having all flags set.
+    fn all() -> Self {
+        let none: Self = Flags::none();
+        !none
+    }
+}
+
 macro_rules! flag_type(
     ($typename:ident : $supertype:ident { $($name:ident = $value:expr),* }) => {
         pub struct $typename {
@@ -99,6 +117,12 @@ macro_rules! flag_type(
             }
         }
 
+        impl ::flags::Flags for $typename {
+            fn none() -> $typename {
+                $typename { bits: 0 as $supertype }
+            }
+        }
+
         $(
             pub static $name: $typename = $typename { bits: $value as $supertype };
         )+

src/sdl2/joystick.rs

@@ -1,4 +1,4 @@
-mod flag;
+mod flags;
 
 #[allow(non_camel_case_types)]
 pub mod ll {

src/sdl2/keyboard.rs

@@ -9,7 +9,7 @@ use rect::Rect;
 use scancode::ScanCode;
 use video::Window;
 
-mod flag;
+mod flags;
 
 #[allow(non_camel_case_types)]
 pub mod ll {

src/sdl2/lib.rs

@@ -33,3 +33,4 @@ pub mod rwops;
 pub mod sdl;
 pub mod audio;
 pub mod version;
+pub mod flags;

src/sdl2/mouse.rs

@@ -4,7 +4,7 @@ use get_error;
 use surface;
 use video;
 
-mod flag;
+mod flags;
 
 #[allow(non_camel_case_types)]
 pub mod ll {

src/sdl2/render.rs

@@ -13,7 +13,7 @@ use std::num::FromPrimitive;
 use std::vec::Vec;
 use std::c_vec::CVec;
 
-mod flag;
+mod flags;
 
 #[allow(non_camel_case_types)]
 pub mod ll {

src/sdl2/sdl.rs

@@ -1,7 +1,7 @@
 use std::cast;
 use std::str;
 
-mod flag;
+mod flags;
 
 // Setup linking for all targets.
 #[cfg(target_os="macos")]

src/sdl2/surface.rs

@@ -6,7 +6,7 @@ use libc::c_int;
 use pixels;
 use rwops;
 
-mod flag;
+mod flags;
 
 #[allow(non_camel_case_types)]
 pub mod ll {

src/sdl2/video.rs

@@ -11,7 +11,7 @@ use std::num::FromPrimitive;
 
 use get_error;
 
-mod flag;
+mod flags;
 
 #[allow(non_camel_case_types)]
 pub mod ll {