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//! Miscellaneous utilities.
use std::borrow::Cow;
use std::ffi::CStr;
use std::mem::transmute;
use std::str;
/// Converts a `char *` which is known to be valid UTF-8 into a `&str`
///
/// The usual `from_glib_none(s)` allocates an owned String. The
/// purpose of `utf8_cstr()` is to get a temporary string slice into a
/// C string which is already known to be valid UTF-8; for example,
/// as for strings which come from `libxml2`.
pub unsafe fn utf8_cstr<'a>(s: *const libc::c_char) -> &'a str {
assert!(!s.is_null());
str::from_utf8_unchecked(CStr::from_ptr(s).to_bytes())
}
pub unsafe fn opt_utf8_cstr<'a>(s: *const libc::c_char) -> Option<&'a str> {
if s.is_null() {
None
} else {
Some(utf8_cstr(s))
}
}
/// Error-tolerant C string import
pub unsafe fn cstr<'a>(s: *const libc::c_char) -> Cow<'a, str> {
if s.is_null() {
return Cow::Borrowed("(null)");
}
CStr::from_ptr(s).to_string_lossy()
}
/// Casts a pointer to `c_char` to a pointer to `u8`.
///
/// The obvious `p as *const u8` or `p as *const _` produces a
/// trivial_casts warning when compiled on aarch64, where `c_char` is
/// unsigned (on Intel, it is signed, so the cast works).
///
/// We do this here with a `transmute`, which is awkward to type,
/// so wrap it in a function.
pub unsafe fn c_char_as_u8_ptr(p: *const libc::c_char) -> *const u8 {
transmute::<_, *const u8>(p)
}
/// Casts a pointer to `c_char` to a pointer to mutable `u8`.
///
/// See [`c_char_as_u8_ptr`] for the reason for this.
pub unsafe fn c_char_as_u8_ptr_mut(p: *mut libc::c_char) -> *mut u8 {
transmute::<_, *mut u8>(p)
}
pub fn clamp<T: PartialOrd>(val: T, low: T, high: T) -> T {
if val < low {
low
} else if val > high {
high
} else {
val
}
}
#[macro_export]
macro_rules! enum_default {
($name:ident, $default:expr) => {
impl Default for $name {
#[inline]
fn default() -> $name {
$default
}
}
};
}
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