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use std::fmt::{self, Display};
use std::ffi::CStr;
use std::os::raw::c_char;
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct ConstCStr {
val: &'static str,
}
impl ConstCStr {
#[inline]
pub const unsafe fn from_str_with_nul_unchecked(val: &'static str) -> ConstCStr {
ConstCStr { val }
}
#[inline]
pub fn as_str(self) -> &'static str {
&self.val[..self.val.len() - 1]
}
#[inline]
pub fn as_bytes(self) -> &'static [u8] {
self.as_str().as_bytes()
}
#[inline]
pub const fn as_bytes_with_nul(self) -> &'static [u8] {
self.val.as_bytes()
}
#[inline]
pub const fn as_ptr(self) -> *const c_char {
self.val.as_bytes().as_ptr() as *const c_char
}
#[inline]
pub fn as_cstr(self) -> &'static CStr {
unsafe { CStr::from_bytes_with_nul_unchecked(self.as_bytes_with_nul()) }
}
}
impl Display for ConstCStr {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> fmt::Result {
self.as_str().fmt(f)
}
}
impl Default for ConstCStr {
#[inline]
fn default() -> ConstCStr {
const_cstr!("")
}
}
impl AsRef<str> for ConstCStr {
fn as_ref(&self) -> &str {
self.as_str()
}
}
impl AsRef<[u8]> for ConstCStr {
fn as_ref(&self) -> &[u8] {
self.as_bytes()
}
}
impl AsRef<CStr> for ConstCStr {
fn as_ref(&self) -> &CStr {
self.as_cstr()
}
}
impl From<ConstCStr> for &'static str {
fn from(c: ConstCStr) -> &'static str {
c.as_str()
}
}
impl From<ConstCStr> for &'static [u8] {
fn from(c: ConstCStr) -> &'static [u8] {
c.as_bytes()
}
}
impl From<ConstCStr> for *const c_char {
fn from(c: ConstCStr) -> *const c_char {
c.as_ptr()
}
}
impl From<ConstCStr> for &'static CStr {
fn from(c: ConstCStr) -> &'static CStr {
c.as_cstr()
}
}
#[macro_export]
macro_rules! const_cstr {
($strval:expr) => {
unsafe { $crate::ConstCStr::from_str_with_nul_unchecked(concat!($strval, "\0")) }
};
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
const HELLO: ConstCStr = const_cstr!("Hello, World!");
assert_eq!(HELLO.as_str(), "Hello, World!");
assert_eq!(HELLO.as_bytes(), b"Hello, World!");
assert_eq!(HELLO.as_bytes_with_nul(), b"Hello, World!\0");
assert_eq!(
unsafe { CStr::from_ptr(HELLO.as_ptr()) },
CStr::from_bytes_with_nul(b"Hello, World!\0").unwrap(),
);
assert_eq!(
HELLO.as_cstr(),
CStr::from_bytes_with_nul(b"Hello, World!\0").unwrap(),
);
}
}