Struct widestring::WideCString

pub struct WideCString { /* fields omitted */ }

An owned, mutable C-style "wide" string for FFI that is nul-aware and nul-terminated.

WideCString is aware of nul values. Unless unchecked conversions are used, all WideCString strings end with a nul-terminator in the underlying buffer and contain no internal nul values. The strings may still contain invalid or ill-formed UTF-16 data. These strings are intended to be used with FFI functions such as Windows API that may require nul-terminated strings.

WideCString can be converted to and from many other string types, including WideString, OsString, and String, making proper Unicode Windows FFI safe and easy.

Examples

The following example constructs a WideCString and shows how to convert a WideCString to a regular Rust String.

use widestring::WideCString;
let v = vec![84u16, 104u16, 101u16]; // 'T' 'h' 'e'
// Create a wide string from the vector
let wstr = WideCString::new(v).unwrap();
// Convert to a rust string!
let rust_str = wstr.to_string_lossy();
assert_eq!(rust_str, "The");

Methods

impl WideCString

pub fn new<T: Into<Vec<u16>>>(v: T) -> Result<WideCString, NulError>

Constructs a WideCString from a container of wide character data.

This method will consume the provided data and use the underlying elements to construct a new string. The data will be scanned for invalid nul values.

Failures

This function will return an error if the data contains a nul value. The returned error will contain the Vec<u16> as well as the position of the nul value.

Examples

use widestring::WideCString;
let v = vec![84u16, 104u16, 101u16]; // 'T' 'h' 'e'
// Create a wide string from the vector
let wcstr = WideCString::new(v).unwrap();

The following example demonstrates errors from nul values in a vector.

use widestring::WideCString;
let v = vec![84u16, 0u16, 104u16, 101u16]; // 'T' NUL 'h' 'e'
// Create a wide string from the vector
let res = WideCString::new(v);
assert!(res.is_err());
assert_eq!(res.err().unwrap().nul_position(), 1);

pub fn from_vec_with_nul<T: Into<Vec<u16>>>(
    v: T
) -> Result<WideCString, MissingNulError>

Constructs a WideCString from a nul-terminated container of UTF-16 data.

This method will consume the provided data and use the underlying elements to construct a new string. The string will be truncated at the first nul value in the string.

Failures

This function will return an error if the data does not contain a nul to terminate the string. The returned error will contain the consumed Vec<u16>.

Examples

use widestring::WideCString;
let v = vec![84u16, 104u16, 101u16, 0u16]; // 'T' 'h' 'e' NUL
// Create a wide string from the vector
let wcstr = WideCString::from_vec_with_nul(v).unwrap();

The following example demonstrates errors from missing nul values in a vector.

use widestring::WideCString;
let v = vec![84u16, 104u16, 101u16]; // 'T' 'h' 'e'
// Create a wide string from the vector
let res = WideCString::from_vec_with_nul(v);
assert!(res.is_err());

pub unsafe fn from_vec_unchecked<T: Into<Vec<u16>>>(v: T) -> WideCString

Creates a WideCString from a vector without checking for interior nul values.

A terminating nul value will be appended if the vector does not already have a terminating nul.

Safety

This method is equivalent to new except that no runtime assertion is made that v contains no nul values. Providing a vector with nul values will result in an invalid WideCString.

pub unsafe fn from_vec_with_nul_unchecked<T: Into<Vec<u16>>>(
    v: T
) -> WideCString

Creates a WideCString from a vector that should have a nul terminator, without checking for any nul values.

Safety

This method is equivalent to from_vec_with_nul except that no runtime assertion is made that v contains no nul values. Providing a vector with interior nul values or without a terminating nul value will result in an invalid WideCString.

pub fn from_str<T: AsRef<OsStr>>(s: T) -> Result<WideCString, NulError>

Constructs a WideCString from anything that can be converted to an OsStr.

The string will be scanned for invalid nul values.

Failures

This function will return an error if the data contains a nul value. The returned error will contain a Vec<u16> as well as the position of the nul value.

Examples

use widestring::WideCString;
let s = "MyString";
// Create a wide string from the string
let wcstr = WideCString::from_str(s).unwrap();

The following example demonstrates errors from nul values in a vector.

use widestring::WideCString;
let s = "My\u{0}String";
// Create a wide string from the string
let res = WideCString::from_str(s);
assert!(res.is_err());
assert_eq!(res.err().unwrap().nul_position(), 2);

pub unsafe fn from_str_unchecked<T: AsRef<OsStr>>(s: T) -> WideCString

Constructs a WideCString from anything that can be converted to an OsStr, without checking for interior nul values.

Safety

This method is equivalent to from_str except that no runtime assertion is made that s contains no nul values. Providing a string with nul values will result in an invalid WideCString.

Examples

use widestring::WideCString;
let s = "MyString";
// Create a wide string from the string
let wcstr = unsafe { WideCString::from_str_unchecked(s) };

pub fn from_str_with_nul<T: AsRef<OsStr>>(
    s: T
) -> Result<WideCString, MissingNulError>

Constructs a WideCString from anything that can be converted to an OsStr with a nul terminator.

The string will be truncated at the first nul value in the string.

Failures

This function will return an error if the data does not contain a nul to terminate the string. The returned error will contain the consumed Vec<u16>.

Examples

use widestring::WideCString;
let s = "My\u{0}String";
// Create a wide string from the string
let wcstr = WideCString::from_str_with_nul(s).unwrap();
assert_eq!(wcstr.to_string_lossy(), "My");

The following example demonstrates errors from missing nul values in a vector.

use widestring::WideCString;
let s = "MyString";
// Create a wide string from the string
let res = WideCString::from_str_with_nul(s);
assert!(res.is_err());

pub unsafe fn from_str_with_nul_unchecked<T: AsRef<OsStr>>(s: T) -> WideCString

Constructs a WideCString from anything that can be converted to an OsStr that should have a terminating nul, but without checking for any nul values.

Safety

This method is equivalent to from_str_with_nul except that no runtime assertion is made that s contains no nul values. Providing a vector with interior nul values or without a terminating nul value will result in an invalid WideCString.

Examples

use widestring::WideCString;
let s = "My String\u{0}";
// Create a wide string from the string
let wcstr = unsafe { WideCString::from_str_with_nul_unchecked(s) };
assert_eq!(wcstr.to_string_lossy(), "My String");

pub fn from_wide_str<T: AsRef<WideStr>>(s: T) -> Result<WideCString, NulError>

Constructs a WideCString from anything that can be converted to a WideStr.

The string will be scanned for invalid nul values.

Failures

This function will return an error if the data contains a nul value. The returned error will contain a Vec<u16> as well as the position of the nul value.

pub unsafe fn from_wide_str_unchecked<T: AsRef<WideStr>>(s: T) -> WideCString

Constructs a WideCString from anything that can be converted to a WideStr, without scanning for invalid nul values.

Safety

This method is equivalent to from_wide_str except that no runtime assertion is made that s contains no nul values. Providing a string with nul values will result in an invalid WideCString.

pub fn from_wide_str_with_nul<T: AsRef<WideStr>>(
    s: T
) -> Result<WideCString, MissingNulError>

Constructs a WideCString from anything that can be converted to a WideStr with a nul terminator.

The string will be truncated at the first nul value in the string.

Failures

This function will return an error if the data does not contain a nul to terminate the string. The returned error will contain the consumed Vec<u16>.

pub unsafe fn from_wide_str_with_nul_unchecked<T: AsRef<WideStr>>(
    s: T
) -> WideCString

Constructs a WideCString from anything that can be converted to a WideStr with a nul terminator, without checking the string for any invalid interior nul values.

Safety

This method is equivalent to from_wide_str_with_nul except that no runtime assertion is made that s contains no nul values. Providing a vector with interior nul values or without a terminating nul value will result in an invalid WideCString.

pub unsafe fn from_ptr_str(p: *const u16) -> WideCString

Constructs a new WideCString copied from a u16 nul-terminated string pointer.

This will scan for nul values beginning with p. The first nul value will be used as the nul terminator for the string, similar to how libc string functions such as strlen work.

Safety

This function is unsafe as there is no guarantee that the given pointer is valid or has a nul terminator, and the function could scan past the underlying buffer.

p must be non-null.

Panics

This function panics if p is null.

Caveat

The lifetime for the returned string is inferred from its usage. To prevent accidental misuse, it's suggested to tie the lifetime to whichever source lifetime is safe in the context, such as by providing a helper function taking the lifetime of a host value for the string, or by explicit annotation.

pub unsafe fn from_ptr(
    p: *const u16,
    len: usize
) -> Result<WideCString, NulError>

Constructs a new WideCString copied from a u16 pointer and a length.

The len argument is the number of u16 elements, not the number of bytes.

The string will be scanned for invalid nul values.

Failures

This function will return an error if the data contains a nul value. The returned error will contain a Vec<u16> as well as the position of the nul value.

Safety

This function is unsafe as there is no guarantee that the given pointer is valid for len elements.

Panics

Panics if len is greater than 0 but p is a null pointer.

pub unsafe fn from_ptr_unchecked(p: *const u16, len: usize) -> WideCString

Constructs a new WideCString copied from a u16 pointer and a length.

The len argument is the number of u16 elements, not the number of bytes.

The string will not be checked for invalid nul values.

Safety

This function is unsafe as there is no guarantee that the given pointer is valid for len elements. In addition, no checking for invalid nul values is performed, so if any elements of p are a nul value, the resulting WideCString will be invalid.

Panics

Panics if len is greater than 0 but p is a null pointer.

pub unsafe fn from_ptr_with_nul(
    p: *const u16,
    len: usize
) -> Result<WideCString, MissingNulError>

Constructs a new WideString copied from a u16 pointer and a length.

The len argument is the number of u16 elements, not the number of bytes.

The string will be truncated at the first nul value in the string.

Failures

This function will return an error if the data does not contain a nul to terminate the string. The returned error will contain the consumed Vec<u16>.

Safety

This function is unsafe as there is no guarantee that the given pointer is valid for len elements.

Panics

Panics if len is greater than 0 but p is a null pointer.

pub unsafe fn from_ptr_with_nul_unchecked(
    p: *const u16,
    len: usize
) -> WideCString

Constructs a new WideString copied from a u16 pointer and a length.

The len argument is the number of u16 elements, not the number of bytes.

The data should end with a nul terminator, but no checking is done on whether the data actually ends with a nul terminator, or if the data contains any interior nul values.

Safety

This function is unsafe as there is no guarantee that the given pointer is valid for len elements. In addition, no checking for nul values is performed, so if there data does not end with a nul terminator, or if there are any interior nul values, the resulting WideCString will be invalid.

Panics

Panics if len is greater than 0 but p is a null pointer.

pub fn as_wide_c_str(&self) -> &WideCStr

Converts to a WideCStr reference.

pub fn into_vec(self) -> Vec<u16>

Converts the wide string into a Vec<u16> without a nul terminator, consuming the string in the process.

The resulting vector will not contain a nul-terminator, and will contain no other nul values.

pub fn into_vec_with_nul(self) -> Vec<u16>

Converts the wide string into a Vec<u16>, consuming the string in the process.

The resulting vector will contain a nul-terminator and no interior nul values.

pub fn into_raw(self) -> *mut u16

Transfers ownership of the wide string to a C caller.

Safety

The pointer must be returned to Rust and reconstituted using from_raw to be properly deallocated. Specifically, one should not use the standard C free function to deallocate this string.

Failure to call from_raw will lead to a memory leak.

pub unsafe fn from_raw(p: *mut u16) -> WideCString

Retakes ownership of a WideCString that was transferred to C.

Safety

This should only ever be called with a pointer that was earlier obtained by calling into_raw on a WideCString. Additionally, the length of the string will be recalculated from the pointer.

pub fn into_boxed_wide_c_str(self) -> Box<WideCStr>

Converts this WideCString into a boxed WideCStr.

Examples

use widestring::{WideCString, WideCStr};

let mut v = vec![102u16, 111u16, 111u16]; // "foo"
let c_string = WideCString::new(v.clone()).unwrap();
let boxed = c_string.into_boxed_wide_c_str();
v.push(0);
assert_eq!(&*boxed, WideCStr::from_slice_with_nul(&v).unwrap());

Methods from Deref<Target = WideCStr>

pub fn to_wide_c_string(&self) -> WideCString

Copies the wide string to an new owned WideString.

pub fn to_os_string(&self) -> OsString

Decodes a wide string to an owned OsString.

This makes a string copy of the WideCStr. Since WideCStr makes no guarantees that it is valid UTF-16, there is no guarantee that the resulting OsString will be valid data. The OsString will not have a nul terminator.

Examples

use widestring::WideCString;
use std::ffi::OsString;
let s = "MyString";
// Create a wide string from the string
let wstr = WideCString::from_str(s).unwrap();
// Create an OsString from the wide string
let osstr = wstr.to_os_string();

assert_eq!(osstr, OsString::from(s));

pub fn to_wide_string(&self) -> WideString

Copies the wide string to a new owned WideString.

The WideString will not have a nul terminator.

pub fn to_string(&self) -> Result<String, FromUtf16Error>

Copies the wide string to a String if it contains valid UTF-16 data.

Failures

Returns an error if the string contains any invalid UTF-16 data.

Examples

use widestring::WideCString;
let s = "MyString";
// Create a wide string from the string
let wstr = WideCString::from_str(s).unwrap();
// Create a regular string from the wide string
let s2 = wstr.to_string().unwrap();

assert_eq!(s2, s);

pub fn to_string_lossy(&self) -> String

Copies the wide string to a String.

Any non-Unicode sequences are replaced with U+FFFD REPLACEMENT CHARACTER.

Examples

use widestring::WideCString;
let s = "MyString";
// Create a wide string from the string
let wstr = WideCString::from_str(s).unwrap();
// Create a regular string from the wide string
let s2 = wstr.to_string_lossy();

assert_eq!(s2, s);

pub fn as_slice(&self) -> &[u16]

Converts to a slice of the wide string.

The slice will not include the nul terminator.

pub fn as_slice_with_nul(&self) -> &[u16]

Converts to a slice of the wide string, including the nul terminator.

pub fn as_ptr(&self) -> *const u16

Returns a raw pointer to the wide string.

The pointer is valid only as long as the lifetime of this reference.

pub fn len(&self) -> usize

Returns the length of the wide string as number of UTF-16 code units (not code points and not number of bytes) not including nul terminator.

pub fn is_empty(&self) -> bool

Returns whether this wide string contains no data (i.e. is only the nul terminator).

Trait Implementations

impl Debug for WideCString

fn fmt(&self, __arg_0: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Clone for WideCString

fn clone(&self) -> WideCString

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl PartialEq for WideCString

fn eq(&self, __arg_0: &WideCString) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, __arg_0: &WideCString) -> bool

This method tests for !=.

impl Eq for WideCString

impl PartialOrd for WideCString

fn partial_cmp(&self, __arg_0: &WideCString) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, __arg_0: &WideCString) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, __arg_0: &WideCString) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, __arg_0: &WideCString) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, __arg_0: &WideCString) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl Ord for WideCString

fn cmp(&self, __arg_0: &WideCString) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

impl Hash for WideCString

fn hash<__H: Hasher>(&self, __arg_0: &mut __H)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].

impl Into<Vec<u16>> for WideCString

fn into(self) -> Vec<u16>

Performs the conversion.

impl<'a> From<WideCString> for Cow<'a, WideCStr>

fn from(s: WideCString) -> Cow<'a, WideCStr>

Performs the conversion.

impl From<WideCString> for OsString

fn from(s: WideCString) -> OsString

Performs the conversion.

impl From<WideCString> for WideString

fn from(s: WideCString) -> WideString

Performs the conversion.

impl<'a, T: ?Sized + AsRef<WideCStr>> From<&'a T> for WideCString

fn from(s: &'a T) -> WideCString

Performs the conversion.

impl Index<RangeFull> for WideCString

type Output = WideCStr

The returned type after indexing.

fn index(&self, _index: RangeFull) -> &WideCStr

Performs the indexing (container[index]) operation.

impl Deref for WideCString

type Target = WideCStr

The resulting type after dereferencing.

fn deref(&self) -> &WideCStr

Dereferences the value.

impl Default for WideCString

fn default() -> WideCString

Returns the "default value" for a type.

impl Drop for WideCString

fn drop(&mut self)

Executes the destructor for this type.

impl Borrow<WideCStr> for WideCString

fn borrow(&self) -> &WideCStr

Immutably borrows from an owned value.

impl AsRef<WideCStr> for WideCString

fn as_ref(&self) -> &WideCStr

Performs the conversion.

impl AsRef<[u16]> for WideCString

fn as_ref(&self) -> &[u16]

Performs the conversion.

impl From<Box<WideCStr>> for WideCString

fn from(s: Box<WideCStr>) -> WideCString

Performs the conversion.

impl From<WideCString> for Box<WideCStr>

fn from(s: WideCString) -> Box<WideCStr>

Performs the conversion.