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#[cfg(test)]
#[macro_use]
extern crate assert_matches;
use std::ffi::CStr;
use std::str::Utf8Error;
use std::convert::AsRef;
use std::mem::transmute;
use std::os::raw::c_char;
use std::ops::Deref;
use std::fmt;
#[derive(Debug)]
pub enum Utf8CStrError {
NoNulTerm,
EmbeddedNulTerm(usize),
Utf8Error(Utf8Error)
}
#[derive(PartialEq, Eq)]
pub struct Utf8CStr {
inner: CStr,
}
impl fmt::Debug for Utf8CStr {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
let s : &str = self.as_ref();
write!(fmt, "{:?}", s)
}
}
impl fmt::Display for Utf8CStr {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
let s : &str = self.as_ref();
write!(fmt, "{}", s)
}
}
impl Utf8CStr {
pub unsafe fn from_raw_parts<'a>(v: *const c_char, l: usize) -> &'a Self {
transmute((v, l))
}
pub unsafe fn from_ptr_unchecked<'a>(v: *const c_char) -> &'a Self {
Self::from_cstr_unchecked(CStr::from_ptr(v))
}
pub fn from_cstr(v: &CStr) -> Result<&Self, Utf8Error> {
try!(v.to_str());
Ok(unsafe { transmute(v)})
}
pub unsafe fn from_cstr_unchecked(v: &CStr) -> &Utf8CStr {
Self::from_bytes_with_nul_unchecked(v.to_bytes_with_nul())
}
pub fn from_bytes(b: &[u8]) -> Result<&Self, Utf8CStrError> {
for (l, &v) in b[0..b.len() - 1].iter().enumerate() {
if v == b'\0' {
return Err(Utf8CStrError::EmbeddedNulTerm(l));
}
}
if b[b.len() - 1] != b'\0' {
return Err(Utf8CStrError::NoNulTerm);
}
let c : &CStr = unsafe { transmute(b) };
Self::from_cstr(c).map_err(|e| Utf8CStrError::Utf8Error(e))
}
pub unsafe fn from_bytes_with_nul_unchecked(b: &[u8]) -> &Self {
transmute(b)
}
pub fn as_ptr(&self) -> *const c_char {
let v : &CStr = self.as_ref();
v.as_ptr()
}
}
impl AsRef<str> for Utf8CStr {
fn as_ref(&self) -> &str {
unsafe { transmute(self.inner.to_bytes()) }
}
}
impl AsRef<CStr> for Utf8CStr {
fn as_ref(&self) -> &CStr {
unsafe { transmute(self) }
}
}
impl Deref for Utf8CStr {
type Target = str;
fn deref(&self) -> &Self::Target {
self.as_ref()
}
}
#[cfg(test)]
mod tests {
use super::Utf8CStr;
use super::Utf8CStrError;
#[test]
fn it_works() {
let x = Utf8CStr::from_bytes(b"hello\0").unwrap();
assert_matches!(Utf8CStr::from_bytes(b"hell").err().unwrap(), Utf8CStrError::NoNulTerm);
assert_matches!(Utf8CStr::from_bytes(b"hell\0d").err().unwrap(), Utf8CStrError::EmbeddedNulTerm(4));
assert_matches!(Utf8CStr::from_bytes(&[8,1,23,4,0xff, 0]).err().unwrap(), Utf8CStrError::Utf8Error(_));
println!("{:?}", x);
println!("{}", x);
assert_eq!(x, x);
assert!(x != Utf8CStr::from_bytes(b"hell\0").unwrap());
let v = b"hello\0";
let b = unsafe { Utf8CStr::from_raw_parts(v.as_ptr() as *const _, v.len()) };
assert_eq!(b, x);
}
}