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// Copyright 2018 Jacob Kiesel // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. //! This crate provides an easy way to inline selection of input parameters //! based on the platform being targeted. Can be used on any `Sized` type. //! //! This is guaranteed to be a zero cost abstraction, as all calls are inlined. //! //! ``` //! extern crate platform; //! //! use platform::Platform; //! //! fn main() { //! println!("Hello from {}!", //! "unknown" //! .ios("ios") //! .android("android") //! .windows("windows") //! .macos("macos") //! .linux("linux") //! .wasm32("wasm32") //! .emscripten("emscripten") //! ); //! //! // Alternatively, let's pretend the arguments are non-trivial to evaluate. //! // We can also use this on function pointers so long as all the variants can //! // coerce to the same function pointer type. //! println!("Hello from {}!", //! ((|| String::from("unknown")) as fn() -> String) //! .ios(|| String::from("ios")) //! .android(|| String::from("android")) //! .windows(|| String::from("windows")) //! .macos(|| String::from("macos")) //! .linux(|| String::from("linux")) //! .wasm32(|| String::from("wasm32")) //! .emscripten(|| String::from("emscripten")) //! () //! ); //! } //! ``` macro_rules! define_platform { ($platform:ident, $name:tt) => { #[inline(always)] fn $platform(self, _input: Self) -> Self { #[cfg(target_os=$name)] { _input } #[cfg(not(target_os=$name))] { self } } }; } pub trait Platform: Sized { #[inline(always)] fn wasm32(self, _input: Self) -> Self { #[cfg(target_arch = "wasm32")] { _input } #[cfg(not(target_arch = "wasm32"))] { self } } define_platform!(ios, "ios"); define_platform!(android, "android"); define_platform!(windows, "windows"); define_platform!(macos, "macos"); define_platform!(linux, "linux"); define_platform!(emscripten, "emscripten"); define_platform!(freebsd, "freebsd"); define_platform!(openbsd, "openbsd"); define_platform!(dragonfly, "dragonfly"); define_platform!(netbsd, "netbsd"); define_platform!(redox, "redox"); } impl<T> Platform for T {}