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// devela::text::char::scalar::c8
use super::*;
use crate::{Char, CharAscii, MismatchedCapacity};
impl char8 {
/* private helper fns */
// SAFETY: this is not marked as unsafe because it's only used privately
// a few selected operations in this module.
const fn from_char_unchecked(c: char) -> char8 {
char8(c as u32 as u8)
}
/* constants */
/// The lowest Unicode scalar a `char8` can represent, `'\u{00}'`.
pub const MIN: char8 = char8(0x00);
/// The highest Unicode scalar a `char8` can represent, `'\u{FF}'`.
pub const MAX: char8 = char8(0xFF);
/* from_* conversions */
/// Converts an `CharAscii` to `char8`.
pub const fn from_char_ascii(c: CharAscii) -> char8 {
char8(c as u8)
}
/// Converts a `char7` to `char8`.
pub const fn from_char7(c: char7) -> char8 {
char8(c.0.get())
}
/// Tries to convert a `char16` to `char8`.
///
/// # Errors
/// Returns [`MismatchedCapacity`] if the character can't fit in 8 bits.
pub const fn try_from_char16(c: char16) -> Result<char8, MismatchedCapacity> {
let scalar = c.to_scalar();
if Char(scalar).len_bytes() == 1 {
Ok(char8(scalar as u8))
} else {
Err(MismatchedCapacity::too_large(scalar as usize, u8::MAX as usize))
}
}
/// Tries to convert a `charu` to `char8`.
///
/// # Errors
/// Returns [`MismatchedCapacity`] if the character can't fit in 8 bits.
pub const fn try_from_charu(c: charu) -> Result<char8, MismatchedCapacity> {
let scalar = c.to_scalar();
if Char(scalar).len_bytes() == 1 {
Ok(char8(scalar as u8))
} else {
Err(MismatchedCapacity::too_large(scalar as usize, u8::MAX as usize))
}
}
/// Tries to convert a `char` to `char8`.
///
/// # Errors
/// Returns [`MismatchedCapacity`] if the character can't fit in 8 bits.
pub const fn try_from_char(c: char) -> Result<char8, MismatchedCapacity> {
let scalar = c as u32;
if Char(scalar).len_bytes() == 1 {
Ok(char8(scalar as u8))
} else {
Err(MismatchedCapacity::too_large(scalar as usize, u8::MAX as usize))
}
}
/* to_* conversions */
/// Tries to convert this `char8` to `CharAscii`.
///
/// # Errors
/// Returns [`MismatchedCapacity`] if `self` can't fit in 7 bits.
///
/// # Features
/// Makes use of the `unsafe_str` feature if enabled.
pub const fn try_to_char_ascii(self) -> Result<CharAscii, MismatchedCapacity> {
if Char(self.to_scalar()).is_ascii() {
#[cfg(any(feature = "safe_text", not(feature = "unsafe_str")))]
if let Some(c) = CharAscii::from_u8(self.0) {
return Ok(c);
} else {
unreachable![]
}
#[cfg(all(not(feature = "safe_text"), feature = "unsafe_str"))]
// SAFETY: we've already checked it's in range.
return Ok(unsafe { CharAscii::from_u8_unchecked(self.0) });
}
Err(MismatchedCapacity::too_large(self.to_scalar() as usize, 127))
}
/// Tries to convert this `char8` to `char7`.
///
/// # Errors
/// Returns [`MismatchedCapacity`] if `self` can't fit in 7 bits.
pub const fn try_to_char7(self) -> Result<char7, MismatchedCapacity> {
char7::try_from_char8(self)
}
/// Converts this `char8` to `char16`.
pub const fn to_char16(self) -> char16 {
char16::from_char8(self)
}
/// Converts this `char8` to `charu`.
pub const fn to_charu(self) -> charu {
charu::from_char8(self)
}
/// Converts this `char8` to `char`.
#[must_use]
pub const fn to_char(self) -> char {
self.0 as char
}
/// Converts this `char8` to a `u32` Unicode scalar value.
#[must_use]
pub const fn to_scalar(self) -> u32 {
self.0 as u32
}
/// Converts this `char8` to an UTF-8 encoded sequence of bytes.
///
/// Note that this function always returns a 2-byte array, but the actual
/// UTF-8 sequence may be shorter. The unused bytes are set to 0.
//
// https://en.wikipedia.org/wiki/UTF-8#Encoding
#[must_use]
#[allow(clippy::unusual_byte_groupings, clippy::single_match_else)]
pub const fn to_utf8_bytes(self) -> [u8; 2] {
let c = self.0;
match c {
// From 0x0000 to 0x007F:
// the UTF-8 encoding is the same as the scalar value.
0x0000..=0x007F => [c, 0],
// from 0x0080 to 0x00FF:
// the UTF-8 encoding is 110xxxxx 10xxxxxx,
// where xxxxx and xxxxxx are the bits of the scalar value.
0x0080.. => {
let y = 0b10_000000 | (Char::<u8>::CONT_MASK & c);
let x = 0b110_00000 | (c >> 6);
[x, y]
}
}
}
//
/* queries */
/// Returns `true` if this Unicode scalar is a [noncharacter][0].
///
/// [0]: https://www.unicode.org/glossary/#noncharacter
#[must_use]
pub const fn is_noncharacter(self) -> bool {
Char(self.0 as u32).is_noncharacter()
}
/// Returns `true` if this Unicode scalar is an [abstract character][0].
///
/// [0]: https://www.unicode.org/glossary/#abstract_character
#[must_use]
pub const fn is_character(self) -> bool {
!self.is_noncharacter()
}
/// Checks if the value is within the ASCII range.
#[must_use]
pub const fn is_ascii(self) -> bool {
self.0 <= 0x7F
}
/// Makes a copy of the value in its ASCII upper case equivalent.
///
/// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', but non-ASCII letters
/// are unchanged.
pub const fn to_ascii_uppercase(self) -> char8 {
Self::from_char_unchecked(char::to_ascii_uppercase(&self.to_char()))
}
/// Makes a copy of the value in its ASCII lower case equivalent.
///
/// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', but non-ASCII letters
/// are unchanged.
pub const fn to_ascii_lowercase(self) -> char8 {
Self::from_char_unchecked(char::to_ascii_lowercase(&self.to_char()))
}
}