diff options
Diffstat (limited to 'library/core/src/internal_macros.rs')
-rw-r--r-- | library/core/src/internal_macros.rs | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/library/core/src/internal_macros.rs b/library/core/src/internal_macros.rs new file mode 100644 index 000000000..5d4c9ba73 --- /dev/null +++ b/library/core/src/internal_macros.rs @@ -0,0 +1,258 @@ +// implements the unary operator "op &T" +// based on "op T" where T is expected to be `Copy`able +macro_rules! forward_ref_unop { + (impl const $imp:ident, $method:ident for $t:ty) => { + forward_ref_unop!(impl const $imp, $method for $t, + #[stable(feature = "rust1", since = "1.0.0")]); + }; + // Equivalent to the non-const version, with the addition of `rustc_const_unstable` + (impl const $imp:ident, $method:ident for $t:ty, #[$attr:meta]) => { + #[$attr] + #[rustc_const_unstable(feature = "const_ops", issue = "90080")] + impl const $imp for &$t { + type Output = <$t as $imp>::Output; + + #[inline] + fn $method(self) -> <$t as $imp>::Output { + $imp::$method(*self) + } + } + }; + (impl $imp:ident, $method:ident for $t:ty, #[$attr:meta]) => { + #[$attr] + impl $imp for &$t { + type Output = <$t as $imp>::Output; + + #[inline] + fn $method(self) -> <$t as $imp>::Output { + $imp::$method(*self) + } + } + } +} + +// implements binary operators "&T op U", "T op &U", "&T op &U" +// based on "T op U" where T and U are expected to be `Copy`able +macro_rules! forward_ref_binop { + (impl const $imp:ident, $method:ident for $t:ty, $u:ty) => { + forward_ref_binop!(impl const $imp, $method for $t, $u, + #[stable(feature = "rust1", since = "1.0.0")]); + }; + // Equivalent to the non-const version, with the addition of `rustc_const_unstable` + (impl const $imp:ident, $method:ident for $t:ty, $u:ty, #[$attr:meta]) => { + #[$attr] + #[rustc_const_unstable(feature = "const_ops", issue = "90080")] + impl<'a> const $imp<$u> for &'a $t { + type Output = <$t as $imp<$u>>::Output; + + #[inline] + fn $method(self, other: $u) -> <$t as $imp<$u>>::Output { + $imp::$method(*self, other) + } + } + + #[$attr] + #[rustc_const_unstable(feature = "const_ops", issue = "90080")] + impl const $imp<&$u> for $t { + type Output = <$t as $imp<$u>>::Output; + + #[inline] + fn $method(self, other: &$u) -> <$t as $imp<$u>>::Output { + $imp::$method(self, *other) + } + } + + #[$attr] + #[rustc_const_unstable(feature = "const_ops", issue = "90080")] + impl const $imp<&$u> for &$t { + type Output = <$t as $imp<$u>>::Output; + + #[inline] + fn $method(self, other: &$u) -> <$t as $imp<$u>>::Output { + $imp::$method(*self, *other) + } + } + }; + (impl $imp:ident, $method:ident for $t:ty, $u:ty, #[$attr:meta]) => { + #[$attr] + impl<'a> $imp<$u> for &'a $t { + type Output = <$t as $imp<$u>>::Output; + + #[inline] + fn $method(self, other: $u) -> <$t as $imp<$u>>::Output { + $imp::$method(*self, other) + } + } + + #[$attr] + impl $imp<&$u> for $t { + type Output = <$t as $imp<$u>>::Output; + + #[inline] + fn $method(self, other: &$u) -> <$t as $imp<$u>>::Output { + $imp::$method(self, *other) + } + } + + #[$attr] + impl $imp<&$u> for &$t { + type Output = <$t as $imp<$u>>::Output; + + #[inline] + fn $method(self, other: &$u) -> <$t as $imp<$u>>::Output { + $imp::$method(*self, *other) + } + } + } +} + +// implements "T op= &U", based on "T op= U" +// where U is expected to be `Copy`able +macro_rules! forward_ref_op_assign { + (impl $imp:ident, $method:ident for $t:ty, $u:ty) => { + forward_ref_op_assign!(impl $imp, $method for $t, $u, + #[stable(feature = "op_assign_builtins_by_ref", since = "1.22.0")]); + }; + (impl const $imp:ident, $method:ident for $t:ty, $u:ty) => { + forward_ref_op_assign!(impl const $imp, $method for $t, $u, + #[stable(feature = "op_assign_builtins_by_ref", since = "1.22.0")]); + }; + // Equivalent to the non-const version, with the addition of `rustc_const_unstable` + (impl const $imp:ident, $method:ident for $t:ty, $u:ty, #[$attr:meta]) => { + #[$attr] + #[rustc_const_unstable(feature = "const_ops", issue = "90080")] + impl const $imp<&$u> for $t { + #[inline] + fn $method(&mut self, other: &$u) { + $imp::$method(self, *other); + } + } + }; + (impl $imp:ident, $method:ident for $t:ty, $u:ty, #[$attr:meta]) => { + #[$attr] + impl $imp<&$u> for $t { + #[inline] + fn $method(&mut self, other: &$u) { + $imp::$method(self, *other); + } + } + } +} + +/// Create a zero-size type similar to a closure type, but named. +macro_rules! impl_fn_for_zst { + ($( + $( #[$attr: meta] )* + struct $Name: ident impl$( <$( $lifetime : lifetime ),+> )? Fn = + |$( $arg: ident: $ArgTy: ty ),*| -> $ReturnTy: ty + $body: block; + )+) => { + $( + $( #[$attr] )* + struct $Name; + + impl $( <$( $lifetime ),+> )? Fn<($( $ArgTy, )*)> for $Name { + #[inline] + extern "rust-call" fn call(&self, ($( $arg, )*): ($( $ArgTy, )*)) -> $ReturnTy { + $body + } + } + + impl $( <$( $lifetime ),+> )? FnMut<($( $ArgTy, )*)> for $Name { + #[inline] + extern "rust-call" fn call_mut( + &mut self, + ($( $arg, )*): ($( $ArgTy, )*) + ) -> $ReturnTy { + Fn::call(&*self, ($( $arg, )*)) + } + } + + impl $( <$( $lifetime ),+> )? FnOnce<($( $ArgTy, )*)> for $Name { + type Output = $ReturnTy; + + #[inline] + extern "rust-call" fn call_once(self, ($( $arg, )*): ($( $ArgTy, )*)) -> $ReturnTy { + Fn::call(&self, ($( $arg, )*)) + } + } + )+ + } +} + +/// A macro for defining `#[cfg]` if-else statements. +/// +/// `cfg_if` 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. +/// +/// # Example +/// +/// ```ignore(cannot-test-this-because-non-exported-macro) +/// cfg_if! { +/// if #[cfg(unix)] { +/// fn foo() { /* unix specific functionality */ } +/// } else if #[cfg(target_pointer_width = "32")] { +/// fn foo() { /* non-unix, 32-bit functionality */ } +/// } else { +/// fn foo() { /* fallback implementation */ } +/// } +/// } +/// +/// # fn main() {} +/// ``` +// This is a copy of `cfg_if!` from the `cfg_if` crate. +// The recursive invocations should use $crate if this is ever exported. +macro_rules! cfg_if { + // match if/else chains with a final `else` + ( + $( + if #[cfg( $i_meta:meta )] { $( $i_tokens:tt )* } + ) else+ + else { $( $e_tokens:tt )* } + ) => { + cfg_if! { + @__items () ; + $( + (( $i_meta ) ( $( $i_tokens )* )) , + )+ + (() ( $( $e_tokens )* )) , + } + }; + + // Internal and recursive macro to emit all the items + // + // Collects all the previous cfgs in a list at the beginning, so they can be + // negated. After the semicolon is all the remaining items. + (@__items ( $( $_:meta , )* ) ; ) => {}; + ( + @__items ( $( $no:meta , )* ) ; + (( $( $yes:meta )? ) ( $( $tokens:tt )* )) , + $( $rest:tt , )* + ) => { + // Emit all items within one block, applying an appropriate #[cfg]. The + // #[cfg] will require all `$yes` matchers specified and must also negate + // all previous matchers. + #[cfg(all( + $( $yes , )? + not(any( $( $no ),* )) + ))] + cfg_if! { @__identity $( $tokens )* } + + // Recurse to emit all other items in `$rest`, and when we do so add all + // our `$yes` matchers to the list of `$no` matchers as future emissions + // will have to negate everything we just matched as well. + cfg_if! { + @__items ( $( $no , )* $( $yes , )? ) ; + $( $rest , )* + } + }; + + // Internal macro to make __apply work out right for different match types, + // because of how macros match/expand stuff. + (@__identity $( $tokens:tt )* ) => { + $( $tokens )* + }; +} |