nu_utils/
module_path.rs

1#[doc(hidden)]
2pub mod __private {
3    /// Returns the module path without the leading crate segment.
4    ///
5    /// For example:
6    /// - `"crate::a::b"` -> `"a::b"`
7    ///
8    /// This looks for the first occurrence of `"::"` and returns everything after it.
9    ///
10    /// # Panics
11    ///
12    /// Panics if `full` does not contain `"::"`.
13    pub const fn module_path_without_crate_impl(full: &str) -> &str {
14        let mut bytes = full.as_bytes();
15
16        while let [first, rest @ ..] = bytes {
17            bytes = rest;
18            if *first == b':' {
19                match rest {
20                    [second, rest @ ..] if *second == b':' => {
21                        // SAFETY:
22                        // - `full` is a valid `&str`, so `bytes` is valid UTF-8.
23                        // - `:` is ASCII (1 byte), so `rest` is guaranteed to start on a UTF-8 code point boundary.
24                        // - Therefore the resulting byte slice is valid UTF-8, making `from_utf8_unchecked` sound.
25                        // - Also this is required as dynamically slicing a &str is not possible in stable rust yet.
26                        return unsafe { str::from_utf8_unchecked(rest) };
27                    }
28                    _ => (),
29                }
30            }
31        }
32
33        panic!("expected a module path containing '::', like 'crate::module'");
34    }
35}
36
37/// Expands to the current module path without the crate name.
38///
39/// This behaves like [`module_path!`], but removes the leading crate segment.
40///
41/// # Panics
42///
43/// Panics if invoked from the crate root, because [`module_path!`] expands to
44/// just the crate name there, which does not contain `"::"`.
45#[macro_export]
46macro_rules! module_path_without_crate {
47    () => {
48        const { $crate::module_path::__private::module_path_without_crate_impl(module_path!()) }
49    };
50}
51
52#[cfg(test)]
53mod tests {
54    use super::__private::module_path_without_crate_impl;
55
56    #[test]
57    fn impl_strips_first_segment() {
58        assert_eq!("b", const { module_path_without_crate_impl("a::b") });
59        assert_eq!("b::c", const { module_path_without_crate_impl("a::b::c") });
60        assert_eq!(
61            "nested::module::item",
62            const { module_path_without_crate_impl("crate::nested::module::item") }
63        );
64    }
65
66    #[test]
67    fn impl_allows_non_ascii_after_separator() {
68        assert_eq!(
69            "mödule::ty",
70            const { module_path_without_crate_impl("crate::mödule::ty") }
71        );
72    }
73
74    #[test]
75    #[should_panic(expected = "expected a module path containing '::'")]
76    fn impl_panics_when_no_separator_exists() {
77        let _ = module_path_without_crate_impl("crate");
78    }
79
80    #[test]
81    fn macro_matches_module_path_suffix_here() {
82        assert_eq!("module_path::tests", crate::module_path_without_crate!());
83    }
84
85    #[test]
86    fn macro_matches_module_path_suffix_in_nested_module() {
87        mod nested {
88            pub fn value() -> &'static str {
89                crate::module_path_without_crate!()
90            }
91        }
92
93        assert_eq!("module_path::tests::nested", nested::value());
94    }
95}
nu_utils/module_path.rs

nu_utils/
module_path.rs
