Trait encode_unicode::CharExt

source · [−]
pub trait CharExt: Sized {

Show 16 methods    fn to_utf8(self) -> Utf8Char;
    fn to_utf16(self) -> Utf16Char;
    fn iter_utf8_bytes(self) -> Utf8IteratorⓘNotable traits for Utf8Iteratorimpl Iterator for Utf8Iterator    type Item = u8;impl Read for Utf8Iterator;
    fn iter_utf16_units(self) -> Utf16IteratorⓘNotable traits for Utf16Iteratorimpl Iterator for Utf16Iterator    type Item = u16;;
    fn to_utf8_array(self) -> ([u8; 4], usize);
    fn to_utf16_array(self) -> [u16; 2];
    fn to_utf16_tuple(self) -> (u16, Option<u16>);
    fn from_utf8_slice_start(src: &[u8]) -> Result<(Self, usize), Utf8Error>;
    fn from_utf16_slice_start(
        src: &[u16]
    ) -> Result<(Self, usize), Utf16SliceError>;
    fn from_utf8_array(utf8: [u8; 4]) -> Result<Self, Utf8Error>;
    fn from_utf16_array(utf16: [u16; 2]) -> Result<Self, Utf16ArrayError>;
    fn from_utf16_tuple(
        utf16: (u16, Option<u16>)
    ) -> Result<Self, Utf16TupleError>;
    unsafe fn from_utf8_exact_slice_unchecked(src: &[u8]) -> Self;
    fn from_utf16_array_unchecked(utf16: [u16; 2]) -> Self;
    unsafe fn from_utf16_tuple_unchecked(utf16: (u16, Option<u16>)) -> Self;
    fn from_u32_detailed(c: u32) -> Result<Self, CodepointError>;

}
Expand description

Extension trait for char that adds methods for converting to and from UTF-8 or UTF-16.

Required Methods

Get the UTF-8 representation of this codepoint.

Utf8Char is to [u8;4] what char is to u32: a restricted type that cannot be mutated internally.

Get the UTF-16 representation of this codepoint.

Utf16Char is to [u16;2] what char is to u32: a restricted type that cannot be mutated internally.

Iterate over or read the one to four bytes in the UTF-8 representation of this codepoint.

An identical alternative to the unstable char.encode_utf8(). That method somehow still exist on stable, so I have to use a different name.

Iterate over the one or two units in the UTF-16 representation of this codepoint.

An identical alternative to the unstable char.encode_utf16(). That method somehow still exist on stable, so I have to use a different name.

Convert this char to an UTF-8 array, and also return how many bytes of the array are used,

The returned array is left-aligned with unused bytes set to zero.

Convert this char to UTF-16.

The second element is non-zero when a surrogate pair is required.

Examples
use encode_unicode::CharExt;

assert_eq!('@'.to_utf16_array(), ['@' as u16, 0]);
assert_eq!('睷'.to_utf16_array(), ['睷' as u16, 0]);
assert_eq!('\u{abcde}'.to_utf16_array(), [0xda6f, 0xdcde]);

Convert this char to UTF-16. The second item is Some if a surrogate pair is required.

Examples
use encode_unicode::CharExt;

assert_eq!('@'.to_utf16_tuple(), ('@' as u16, None));
assert_eq!('睷'.to_utf16_tuple(), ('睷' as u16, None));
assert_eq!('\u{abcde}'.to_utf16_tuple(), (0xda6f, Some(0xdcde)));

Create a char from the start of an UTF-8 slice, and also return how many bytes were used.

Errors

Returns an Err if the slice is empty, doesn’t start with a valid UTF-8 sequence or is too short for the sequence.

Examples
use encode_unicode::CharExt;
use encode_unicode::error::Utf8ErrorKind::*;

assert_eq!(char::from_utf8_slice_start(&[b'A', b'B', b'C']), Ok(('A',1)));
assert_eq!(char::from_utf8_slice_start(&[0xdd, 0xbb]), Ok(('\u{77b}',2)));

assert_eq!(char::from_utf8_slice_start(&[]).unwrap_err(), TooFewBytes);
assert_eq!(char::from_utf8_slice_start(&[0xf0, 0x99]).unwrap_err(), TooFewBytes);
assert_eq!(char::from_utf8_slice_start(&[0xee, b'F', 0x80]).unwrap_err(), InterruptedSequence);
assert_eq!(char::from_utf8_slice_start(&[0xee, 0x99, 0x0f]).unwrap_err(), InterruptedSequence);

Create a char from the start of an UTF-16 slice, and also return how many units were used.

If you want to continue after an error, continue with the next u16 unit.

Convert an UTF-8 sequence as returned from .to_utf8_array() into a char

The codepoint must start at the first byte, and leftover bytes are ignored.

Errors

Returns an Err if the array doesn’t start with a valid UTF-8 sequence.

Examples
use encode_unicode::CharExt;
use encode_unicode::error::Utf8ErrorKind::*;

assert_eq!(char::from_utf8_array([b'A', 0, 0, 0]), Ok('A'));
assert_eq!(char::from_utf8_array([0xf4, 0x8b, 0xbb, 0xbb]), Ok('\u{10befb}'));
assert_eq!(char::from_utf8_array([b'A', b'B', b'C', b'D']), Ok('A'));
assert_eq!(char::from_utf8_array([0, 0, 0xcc, 0xbb]), Ok('\0'));

assert_eq!(char::from_utf8_array([0xef, b'F', 0x80, 0x80]).unwrap_err(), InterruptedSequence);
assert_eq!(char::from_utf8_array([0xc1, 0x80, 0, 0]).unwrap_err().kind(), NonUtf8Byte);
assert_eq!(char::from_utf8_array([0xe0, 0x9a, 0xbf, 0]).unwrap_err().kind(), OverlongEncoding);
assert_eq!(char::from_utf8_array([0xf4, 0xaa, 0x99, 0x88]).unwrap_err(), TooHighCodepoint);

Convert a UTF-16 pair as returned from .to_utf16_array() into a char.

The second element is ignored when not required.

Examples
use encode_unicode::CharExt;
use encode_unicode::error::Utf16ArrayError;

assert_eq!(char::from_utf16_array(['x' as u16, 'y' as u16]), Ok('x'));
assert_eq!(char::from_utf16_array(['睷' as u16, 0]), Ok('睷'));
assert_eq!(char::from_utf16_array([0xda6f, 0xdcde]), Ok('\u{abcde}'));
assert_eq!(char::from_utf16_array([0xf111, 0xdbad]), Ok('\u{f111}'));
assert_eq!(char::from_utf16_array([0xdaaf, 0xdaaf]), Err(Utf16ArrayError::SecondIsNotTrailingSurrogate));
assert_eq!(char::from_utf16_array([0xdcac, 0x9000]), Err(Utf16ArrayError::FirstIsTrailingSurrogate));

Convert a UTF-16 pair as returned from .to_utf16_tuple() into a char.

Convert an UTF-8 sequence into a char.

The length of the slice is taken as length of the sequence; it should be 1,2,3 or 4.

Safety

The slice must contain exactly one, valid, UTF-8 sequence.

Passing a slice that produces an invalid codepoint is always undefined behavior; Later checks that the codepoint is valid can be removed by the compiler.

Panics

If the slice is empty

Convert a UTF-16 array as returned from .to_utf16_array() into a char.

This function is safe because it avoids creating invalid codepoints, but the returned value might not be what one expectedd.

Examples
use encode_unicode::CharExt;

// starts with a trailing surrogate - converted as if it was a valid
// surrogate pair anyway.
assert_eq!(char::from_utf16_array_unchecked([0xdbad, 0xf19e]), '\u{fb59e}');
// missing trailing surrogate - ditto
assert_eq!(char::from_utf16_array_unchecked([0xd802, 0]), '\u{10800}');

Convert a UTF-16 tuple as returned from .to_utf16_tuple() into a char.

Safety

If the second element is None, the first element must be a codepoint in the basic multilingual pane. (In other words, outside the range0xd8_00..0xe0_00.)
Violating this results in an invalid char in that reserved range being created, which is (or can easily lead to) undefined behavior.

Produces more detailed errors than char::from_u32()

Errors

This function will return an error if

  • the value is greater than 0x10ffff
  • the value is between 0xd800 and 0xdfff (inclusive)
Examples
use encode_unicode::CharExt;
use encode_unicode::error::CodepointError;

assert_eq!(char::from_u32_detailed(0x41), Ok('A'));
assert_eq!(char::from_u32_detailed(0x40_00_00), Err(CodepointError::TooHigh));
assert_eq!(char::from_u32_detailed(0xd951), Err(CodepointError::Utf16Reserved));
assert_eq!(char::from_u32_detailed(0xdddd), Err(CodepointError::Utf16Reserved));
assert_eq!(char::from_u32_detailed(0xdd), Ok('Ý'));
assert_eq!(char::from_u32_detailed(0x1f331), Ok('🌱'));

Implementations on Foreign Types

Implementors