get_random_const/
lib.rs

1//! Simple compile time random generator
2//!
3//! ## Example
4//!
5//! ```rust
6//! use get_random_const::random;
7//!
8//! const RANDOM_U8: u8 = random!(u8);
9//! assert_ne!(RANDOM_U8, 0);
10//!
11//! static RANDOM_I32: i32 = random!(i32);
12//! assert_ne!(RANDOM_I32, 0);
13//!
14//! assert_ne!(random!(u8), 0u8);
15//! assert_ne!(random!(i8), 0i8);
16//! assert_ne!(random!(u16), 0u16);
17//! assert_ne!(random!(i16), 0i16);
18//! assert_ne!(random!(u32), 0u32);
19//! assert_ne!(random!(i32), 0i32);
20//! assert_ne!(random!(u64), 0u64);
21//! assert_ne!(random!(i64), 0i64);
22//! assert_ne!(random!(u128), 0u128);
23//! assert_ne!(random!(i128), 0i128);
24//! assert_ne!(random!(usize), 0usize);
25//! assert_ne!(random!(isize), 0isize);
26//!
27//! let random_array = random!([u32;5]);
28//! assert_eq!(random_array.len(), 5);
29//!
30//! for elem in random_array.iter() {
31//!     assert_ne!(*elem, 0);
32//! }
33//!
34//! let random_array: [u32; 0] = random!([u32;0]); //Well, I guess you can if you want?
35//! assert_eq!(random_array.len(), 0);
36//! ```
37
38
39extern crate proc_macro;
40
41use proc_macro::TokenStream;
42
43use core::mem;
44
45fn randomize<T: Copy>() -> T {
46    let mut val = mem::MaybeUninit::<T>::uninit();
47    let slice = unsafe {
48        core::slice::from_raw_parts_mut(val.as_mut_ptr() as *mut mem::MaybeUninit<u8>, core::mem::size_of::<T>())
49    };
50
51    getrandom::fill_uninit(slice).expect("Failed to generate random number");
52    unsafe {
53        val.assume_init()
54    }
55}
56
57fn randomize_type(path: &str) -> Option<String> {
58    let res = if path.eq_ignore_ascii_case("u8"){
59        let res = randomize::<u8>();
60        format!("{}u8", res)
61    } else if path.eq_ignore_ascii_case("i8") {
62        let res = randomize::<i8>();
63        format!("{}i8", res)
64    } else if path.eq_ignore_ascii_case("u16") {
65        let res = randomize::<u16>();
66        format!("{}u16", res)
67    } else if path.eq_ignore_ascii_case("i16") {
68        let res = randomize::<i16>();
69        format!("{}i16", res)
70    } else if path.eq_ignore_ascii_case("u32") {
71        let res = randomize::<u32>();
72        format!("{}u32", res)
73    } else if path.eq_ignore_ascii_case("i32") {
74        let res = randomize::<i32>();
75        format!("{}i32", res)
76    } else if path.eq_ignore_ascii_case("u64") {
77        let res = randomize::<u64>();
78        format!("{}u64", res)
79    } else if path.eq_ignore_ascii_case("i64") {
80        let res = randomize::<i64>();
81        format!("{}i64", res)
82    } else if path.eq_ignore_ascii_case("u128") {
83        let res = randomize::<u128>();
84        format!("{}u128", res)
85    } else if path.eq_ignore_ascii_case("i128") {
86        let res = randomize::<i128>();
87        format!("{}i128", res)
88    } else if path.eq_ignore_ascii_case("usize") {
89        let res = randomize::<usize>();
90        format!("{}usize", res)
91    } else if path.eq_ignore_ascii_case("isize") {
92        let res = randomize::<isize>();
93        format!("{}isize", res)
94    } else {
95        return None
96    };
97
98    Some(res)
99}
100
101#[proc_macro]
102pub fn random(input: TokenStream) -> TokenStream {
103    let input = input.to_string();
104    let input = input.trim();
105
106    if input.is_empty() {
107        panic!("Empty input :(");
108    } else if input.starts_with('[') {
109        if !input.ends_with(']') {
110            panic!("'{}' is missing right bracket", input);
111        }
112
113        let array_content = input[1..input.len()-1].trim();
114        if array_content.is_empty() {
115            panic!("just empty brackets? Did you mean array?");
116        }
117
118        let mut split = array_content.splitn(2, ';');
119        let typ = split.next().unwrap().trim();
120
121        if randomize_type(typ).is_none() {
122            panic!("'{}' is unsupported", typ);
123        }
124
125        let num = split.next().expect("Missing ';' in array type").trim();
126        let num: usize = num.parse().expect("Array type size is invalid as usize");
127
128        let mut result = "[".to_owned();
129        if num > 0 {
130            for _ in 0..num {
131                result.push_str(randomize_type(typ).unwrap().as_str());
132                result.push(',');
133            }
134            result.pop();
135        }
136        result.push(']');
137
138        result.parse().unwrap()
139    } else if let Some(result) = randomize_type(input) {
140        result.parse().unwrap()
141    } else {
142        panic!("Unsupported type");
143    }
144}
get_random_const/lib.rs

get_random_const/
lib.rs
