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Allow to have multiple conditions in the same macro call #78

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Allow to have multiple conditions in the same macro call #78

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87 changes: 86 additions & 1 deletion src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,11 +22,26 @@
//!
//! # fn main() {}
//! ```
//!
//! You can have other `if` conditions in the same macro call:
//!
//! ```
//! cfg_if::cfg_if! {
//! if #[cfg(unix)] {
//! fn foo() { /* unix specific functionality */ }
//! }
//! if #[cfg(feature = "bar")] {
//! fn bar() {}
//! }
//! }
//!
//! # fn main() {}
//! ```

#![no_std]
#![doc(html_root_url = "https://docs.rs/cfg-if")]
#![deny(missing_docs)]
#![cfg_attr(test, deny(warnings))]
#![cfg_attr(test, deny(warnings), allow(unexpected_cfgs))]

/// The main macro provided by this crate. See crate documentation for more
/// information.
Expand All @@ -48,6 +63,26 @@ macro_rules! cfg_if {
}
};

// Allow to multiple conditions in a same call.
(
$(
if #[cfg( $i_meta:meta )] { $( $i_tokens:tt )* }
) else+
else { $( $e_tokens:tt )* }
if $($extra_conditions:tt)+
) => {
$crate::cfg_if! {
@__items () ;
$(
(( $i_meta ) ( $( $i_tokens )* )) ,
)+
(() ( $( $e_tokens )* )) ,
}
$crate::cfg_if! {
if $($extra_conditions)+
}
};

// match if/else chains lacking a final `else`
(
if #[cfg( $i_meta:meta )] { $( $i_tokens:tt )* }
Expand All @@ -64,6 +99,26 @@ macro_rules! cfg_if {
}
};

// Allow to multiple conditions in a same call.
(
if #[cfg( $i_meta:meta )] { $( $i_tokens:tt )* }
$(
else if #[cfg( $e_meta:meta )] { $( $e_tokens:tt )* }
)*
if $($extra_conditions:tt)+
) => {
$crate::cfg_if! {
@__items () ;
(( $i_meta ) ( $( $i_tokens )* )) ,
$(
(( $e_meta ) ( $( $e_tokens )* )) ,
)*
}
$crate::cfg_if! {
if $($extra_conditions)+
}
};

// Internal and recursive macro to emit all the items
//
// Collects all the previous cfgs in a list at the beginning, so they can be
Expand Down Expand Up @@ -143,13 +198,43 @@ mod tests {
}
}

cfg_if! {
if #[cfg(foo)] {
fn works6() -> bool { false }
} else if #[cfg(test)] {
fn works6() -> bool { true }
}
if #[cfg(test)] {
fn works7() -> bool { true }
} else {
fn works7() -> bool { false }
}
}

cfg_if! {
if #[cfg(test)] {
fn works8() -> bool { true }
} else if #[cfg(foo)] {
fn works8() -> bool { false }
}
if #[cfg(foo)] {
fn works9() -> bool { false }
} else if #[cfg(test)] {
fn works9() -> bool { true }
}
}

#[test]
fn it_works() {
assert!(works1().is_some());
assert!(works2());
assert!(works3());
assert!(works4().is_some());
assert!(works5());
assert!(works6());
assert!(works7());
assert!(works8());
assert!(works9());
}

#[test]
Expand Down