platform/
lib.rs

1// Copyright 2018 Jacob Kiesel
2
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// 	http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15//! This crate provides an easy way to inline selection of input parameters
16//! based on the platform being targeted.  Can be used on any `Sized` type.
17//!
18//! This is guaranteed to be a zero cost abstraction, as all calls are inlined.
19//!
20//! ```
21//! extern crate platform;
22//!
23//! use platform::Platform;
24//!
25//! fn main() {
26//!     println!("Hello from {}!",
27//!         "unknown"
28//!         .ios("ios")
29//!         .android("android")
30//!         .windows("windows")
31//!         .macos("macos")
32//!         .linux("linux")
33//!         .wasm32("wasm32")
34//!         .emscripten("emscripten")
35//!     );
36//!
37//!     // Alternatively, let's pretend the arguments are non-trivial to evaluate.
38//!     // We can also use this on function pointers so long as all the variants can 
39//!     // coerce to the same function pointer type.
40//!     println!("Hello from {}!",
41//!         ((|| String::from("unknown")) as fn() -> String)
42//!         .ios(|| String::from("ios"))
43//!         .android(|| String::from("android"))
44//!         .windows(|| String::from("windows"))
45//!         .macos(|| String::from("macos"))
46//!         .linux(|| String::from("linux"))
47//!         .wasm32(|| String::from("wasm32"))
48//!         .emscripten(|| String::from("emscripten"))
49//!         ()
50//!     );
51//! }
52//! ```
53
54macro_rules! define_platform {
55    ($platform:ident, $name:tt) => {
56        #[inline(always)]
57        fn $platform(self, _input: Self) -> Self {
58            #[cfg(target_os=$name)]
59            {
60                _input
61            }
62            #[cfg(not(target_os=$name))]
63            {
64                self
65            }
66        }
67    };
68}
69
70pub trait Platform: Sized {
71    #[inline(always)]
72    fn wasm32(self, _input: Self) -> Self {
73        #[cfg(target_arch = "wasm32")]
74        {
75            _input
76        }
77
78        #[cfg(not(target_arch = "wasm32"))]
79        {
80            self
81        }
82    }
83    define_platform!(ios, "ios");
84    define_platform!(android, "android");
85    define_platform!(windows, "windows");
86    define_platform!(macos, "macos");
87    define_platform!(linux, "linux");
88    define_platform!(emscripten, "emscripten");
89    define_platform!(freebsd, "freebsd");
90    define_platform!(openbsd, "openbsd");
91    define_platform!(dragonfly, "dragonfly");
92    define_platform!(netbsd, "netbsd");
93    define_platform!(redox, "redox");
94}
95
96impl<T> Platform for T {}
platform/lib.rs

platform/
lib.rs
