1 files changed, 108 insertions, 0 deletions
diff --git a/libc/src/macros.rs b/libc/src/macros.rs
new file mode 100644
index 0000000..5811c84
--- /dev/null
+++ b/libc/src/macros.rs
@@ -0,0 +1,108 @@
+/// A macro for defining #[cfg] if-else statements.
+///
+/// This is similar to the `if/elif` C preprocessor macro by allowing definition
+/// of a cascade of `#[cfg]` cases, emitting the implementation which matches
+/// first.
+///
+/// This allows you to conveniently provide a long list #[cfg]'d blocks of code
+/// without having to rewrite each clause multiple times.
+macro_rules! cfg_if {
+    ($(
+        if #[cfg($($meta:meta),*)] { $($it:item)* }
+    ) else * else {
+        $($it2:item)*
+    }) => {
+        __cfg_if_items! {
+            () ;
+            $( ( ($($meta),*) ($($it)*) ), )*
+            ( () ($($it2)*) ),
+        }
+    }
+}
+
+macro_rules! __cfg_if_items {
+    (($($not:meta,)*) ; ) => {};
+    (($($not:meta,)*) ; ( ($($m:meta),*) ($($it:item)*) ), $($rest:tt)*) => {
+        __cfg_if_apply! { cfg(all(not(any($($not),*)), $($m,)*)), $($it)* }
+        __cfg_if_items! { ($($not,)* $($m,)*) ; $($rest)* }
+    }
+}
+
+macro_rules! __cfg_if_apply {
+    ($m:meta, $($it:item)*) => {
+        $(#[$m] $it)*
+    }
+}
+
+macro_rules! s {
+    ($($(#[$attr:meta])* pub struct $i:ident { $($field:tt)* })*) => ($(
+        __item! {
+            #[repr(C)]
+            $(#[$attr])*
+            pub struct $i { $($field)* }
+        }
+        impl ::dox::Copy for $i {}
+        impl ::dox::Clone for $i {
+            fn clone(&self) -> $i { *self }
+        }
+    )*)
+}
+
+macro_rules! f {
+    ($(pub fn $i:ident($($arg:ident: $argty:ty),*) -> $ret:ty {
+        $($body:stmt);*
+    })*) => ($(
+        #[inline]
+        #[cfg(not(dox))]
+        pub unsafe extern fn $i($($arg: $argty),*) -> $ret {
+            $($body);*
+        }
+
+        #[cfg(dox)]
+        #[allow(dead_code)]
+        pub unsafe extern fn $i($($arg: $argty),*) -> $ret {
+            loop {}
+        }
+    )*)
+}
+
+macro_rules! __item {
+    ($i:item) => ($i)
+}
+
+#[cfg(test)]
+mod tests {
+    cfg_if! {
+        if #[cfg(test)] {
+            use std::option::Option as Option2;
+            fn works1() -> Option2<u32> { Some(1) }
+        } else {
+            fn works1() -> Option<u32> { None }
+        }
+    }
+
+    cfg_if! {
+        if #[cfg(foo)] {
+            fn works2() -> bool { false }
+        } else if #[cfg(test)] {
+            fn works2() -> bool { true }
+        } else {
+            fn works2() -> bool { false }
+        }
+    }
+
+    cfg_if! {
+        if #[cfg(foo)] {
+            fn works3() -> bool { false }
+        } else {
+            fn works3() -> bool { true }
+        }
+    }
+
+    #[test]
+    fn it_works() {
+        assert!(works1().is_some());
+        assert!(works2());
+        assert!(works3());
+    }
+}