ab_riscv_macros_common/
code_utils.rs

1//! This module contains hacks for Rust nightly syntax to make it compatible with `syn`
2// TODO: Remove this module once `syn` supports used Rust nightly syntax
3
4const FROM_TRAIT_CONST_1: &str = "const trait ";
5const TO_TRAIT_CONST_1: &str = "trait _const";
6const FROM_TRAIT_CONST_2: &str = "const unsafe trait ";
7const TO_TRAIT_CONST_2: &str = "unsafe trait _const";
8const FROM_IMPL_CONST_1: &str = "> const ";
9const TO_IMPL_CONST_1: &str = "> cnst::";
10const FROM_IMPL_CONST_2: &str = "> const  ";
11const TO_IMPL_CONST_2: &str = "> cnst ::";
12const FROM_IMPL_CONST_REVERT_1: &str = "pub cnst::";
13const TO_IMPL_CONST_REVERT_1: &str = "pub const ";
14const FROM_IMPL_CONST_REVERT_2: &str = "pub cnst ::";
15const TO_IMPL_CONST_REVERT_2: &str = "pub const  ";
16const FROM_IMPL_CONST_REVERT_3: &str = ") cnst::";
17const TO_IMPL_CONST_REVERT_3: &str = ") const ";
18const FROM_IMPL_CONST_REVERT_4: &str = ") cnst ::";
19const TO_IMPL_CONST_REVERT_4: &str = ") const  ";
20const FROM_IMPL_CONST_REVERT_5: &str = "cnst::fn";
21const TO_IMPL_CONST_REVERT_5: &str = "const fn";
22
23const FROM_BRACKETS_CONST_1: &str = "[const] ";
24const TO_BRACKETS_CONST_1: &str = "BRCONST+";
25const FROM_BRACKETS_CONST_2: &str = " [const] ";
26const TO_BRACKETS_CONST_2: &str = "BRCONST +";
27
28/// Replace bits of Rust nightly syntax with something that is technically valid in stable Rust, so
29/// `syn` can parse it
30pub fn pre_process_rust_code(s: &mut str) {
31    replace_inplace(s, FROM_TRAIT_CONST_1, TO_TRAIT_CONST_1);
32    replace_inplace(s, FROM_TRAIT_CONST_2, TO_TRAIT_CONST_2);
33    replace_inplace(s, FROM_IMPL_CONST_1, TO_IMPL_CONST_1);
34    replace_inplace(s, FROM_IMPL_CONST_2, TO_IMPL_CONST_2);
35    replace_inplace(s, FROM_IMPL_CONST_REVERT_1, TO_IMPL_CONST_REVERT_1);
36    replace_inplace(s, FROM_IMPL_CONST_REVERT_2, TO_IMPL_CONST_REVERT_2);
37    replace_inplace(s, FROM_IMPL_CONST_REVERT_3, TO_IMPL_CONST_REVERT_3);
38    replace_inplace(s, FROM_IMPL_CONST_REVERT_4, TO_IMPL_CONST_REVERT_4);
39    replace_inplace(s, FROM_IMPL_CONST_REVERT_5, TO_IMPL_CONST_REVERT_5);
40    replace_inplace(s, FROM_BRACKETS_CONST_1, TO_BRACKETS_CONST_1);
41    replace_inplace(s, FROM_BRACKETS_CONST_2, TO_BRACKETS_CONST_2);
42}
43
44/// The inverse of [`pre_process_rust_code()`]
45pub fn post_process_rust_code(s: &mut str) {
46    replace_inplace(s, TO_TRAIT_CONST_2, FROM_TRAIT_CONST_2);
47    replace_inplace(s, TO_TRAIT_CONST_1, FROM_TRAIT_CONST_1);
48    replace_inplace(s, TO_IMPL_CONST_1, FROM_IMPL_CONST_1);
49    replace_inplace(s, TO_IMPL_CONST_2, FROM_IMPL_CONST_2);
50    replace_inplace(s, TO_BRACKETS_CONST_1, FROM_BRACKETS_CONST_1);
51    replace_inplace(s, TO_BRACKETS_CONST_2, FROM_BRACKETS_CONST_2);
52}
53
54fn replace_inplace(mut s: &mut str, from: &str, to: &str) {
55    assert_eq!(from.len(), to.len(), "`{from}` != `{to}`");
56
57    if from.is_empty() {
58        return;
59    }
60
61    while let Some(found) = s.find(from) {
62        let start = found;
63        let end = found + from.len();
64
65        // SAFETY: Replacing a valid string with a valid string of the same length
66        unsafe { s.as_bytes_mut() }
67            .get_mut(start..end)
68            .expect("Just found a string of the desired length; qed")
69            .copy_from_slice(to.as_bytes());
70
71        s = &mut s[end..];
72    }
73}
ab_riscv_macros_common/code_utils.rs

ab_riscv_macros_common/
code_utils.rs
