Struct jni::strings::JNIStr
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pub struct JNIStr { /* fields omitted */ }
Wrapper for std::ffi::CStr
that also takes care of encoding between
UTF-8 and Java's Modified UTF-8.
Methods
impl JNIStr
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pub unsafe fn from_ptr<'a>(ptr: *const c_char) -> &'a JNIStr
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Construct a reference to a JNIStr
from a pointer. Equivalent to
CStr::from_ptr
.
Methods from Deref<Target = CStr>
pub fn as_ptr(&self) -> *const i8
1.0.0[src]
Returns the inner pointer to this C string.
The returned pointer will be valid for as long as self
is, and points
to a contiguous region of memory terminated with a 0 byte to represent
the end of the string.
WARNING
It is your responsibility to make sure that the underlying memory is not
freed too early. For example, the following code will cause undefined
behavior when ptr
is used inside the unsafe
block:
use std::ffi::{CString}; let ptr = CString::new("Hello").unwrap().as_ptr(); unsafe { // `ptr` is dangling *ptr; }
This happens because the pointer returned by as_ptr
does not carry any
lifetime information and the CString
is deallocated immediately after
the CString::new("Hello").unwrap().as_ptr()
expression is evaluated.
To fix the problem, bind the CString
to a local variable:
use std::ffi::{CString}; let hello = CString::new("Hello").unwrap(); let ptr = hello.as_ptr(); unsafe { // `ptr` is valid because `hello` is in scope *ptr; }
This way, the lifetime of the CString
in hello
encompasses
the lifetime of ptr
and the unsafe
block.
pub fn to_bytes(&self) -> &[u8]
1.0.0[src]
Converts this C string to a byte slice.
The returned slice will not contain the trailing nul terminator that this C string has.
Note: This method is currently implemented as a constant-time cast, but it is planned to alter its definition in the future to perform the length calculation whenever this method is called.
Examples
use std::ffi::CStr; let c_str = CStr::from_bytes_with_nul(b"foo\0").unwrap(); assert_eq!(c_str.to_bytes(), b"foo");
pub fn to_bytes_with_nul(&self) -> &[u8]
1.0.0[src]
Converts this C string to a byte slice containing the trailing 0 byte.
This function is the equivalent of to_bytes
except that it will retain
the trailing nul terminator instead of chopping it off.
Note: This method is currently implemented as a 0-cost cast, but it is planned to alter its definition in the future to perform the length calculation whenever this method is called.
Examples
use std::ffi::CStr; let c_str = CStr::from_bytes_with_nul(b"foo\0").unwrap(); assert_eq!(c_str.to_bytes_with_nul(), b"foo\0");
pub fn to_str(&self) -> Result<&str, Utf8Error>
1.4.0[src]
Yields a &str
slice if the CStr
contains valid UTF-8.
If the contents of the CStr
are valid UTF-8 data, this
function will return the corresponding &str
slice. Otherwise,
it will return an error with details of where UTF-8 validation failed.
Note: This method is currently implemented to check for validity after a constant-time cast, but it is planned to alter its definition in the future to perform the length calculation in addition to the UTF-8 check whenever this method is called.
Examples
use std::ffi::CStr; let c_str = CStr::from_bytes_with_nul(b"foo\0").unwrap(); assert_eq!(c_str.to_str(), Ok("foo"));
pub fn to_string_lossy(&self) -> Cow<str>
1.4.0[src]
Converts a CStr
into a Cow
<
str
>
.
If the contents of the CStr
are valid UTF-8 data, this
function will return a Cow
::
Borrowed
(
[&str
])
with the the corresponding [&str
] slice. Otherwise, it will
replace any invalid UTF-8 sequences with U+FFFD REPLACEMENT CHARACTER
and return a Cow
::
[Owned
](
String
)
with the result.
Note: This method is currently implemented to check for validity after a constant-time cast, but it is planned to alter its definition in the future to perform the length calculation in addition to the UTF-8 check whenever this method is called.
Examples
Calling to_string_lossy
on a CStr
containing valid UTF-8:
use std::borrow::Cow; use std::ffi::CStr; let c_str = CStr::from_bytes_with_nul(b"Hello World\0").unwrap(); assert_eq!(c_str.to_string_lossy(), Cow::Borrowed("Hello World"));
Calling to_string_lossy
on a CStr
containing invalid UTF-8:
use std::borrow::Cow; use std::ffi::CStr; let c_str = CStr::from_bytes_with_nul(b"Hello \xF0\x90\x80World\0").unwrap(); assert_eq!( c_str.to_string_lossy(), Cow::Owned(String::from("Hello �World")) as Cow<str> );
Trait Implementations
impl Deref for JNIStr
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type Target = CStr
The resulting type after dereferencing.
fn deref(&self) -> &Self::Target
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Dereferences the value.
impl<'a> From<&'a JNIStr> for Cow<'a, str>
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impl Borrow<JNIStr> for JNIString
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impl ToOwned for JNIStr
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type Owned = JNIString
fn to_owned(&self) -> JNIString
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Creates owned data from borrowed data, usually by cloning. Read more
fn clone_into(&self, target: &mut Self::Owned)
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🔬 This is a nightly-only experimental API. (toowned_clone_into
)
recently added
Uses borrowed data to replace owned data, usually by cloning. Read more