qubit_codec_text/charset/
utf32.rs

1// =============================================================================
2//    Copyright (c) 2026 Haixing Hu.
3//
4//    SPDX-License-Identifier: Apache-2.0
5//
6//    Licensed under the Apache License, Version 2.0.
7// =============================================================================
8use crate::{
9    ByteOrder,
10    Unicode,
11    UnicodeBom,
12};
13
14/// Namespace for UTF-32 constants and code-unit classification helpers.
15pub enum Utf32 {}
16
17impl Utf32 {
18    /// Maximum number of UTF-32 code units needed for one Unicode scalar value.
19    pub const MAX_UNITS_PER_CHAR: usize = 1;
20
21    /// Maximum number of serialized UTF-32 bytes needed for one Unicode scalar
22    /// value.
23    pub const MAX_BYTES_PER_CHAR: usize = 4;
24
25    /// Tests whether a UTF-32 unit is a valid Unicode scalar value.
26    ///
27    /// # Parameters
28    ///
29    /// - `unit`: The UTF-32 unit to test.
30    ///
31    /// # Returns
32    ///
33    /// Returns `true` if `unit` is a valid Unicode scalar value.
34    #[inline(always)]
35    pub const fn is_valid_unit(unit: u32) -> bool {
36        Unicode::is_scalar_value(unit)
37    }
38
39    /// Returns the UTF-32 unit count needed for a character.
40    ///
41    /// # Parameters
42    ///
43    /// - `_ch`: The character to size.
44    ///
45    /// # Returns
46    ///
47    /// Always returns `1`.
48    #[inline(always)]
49    pub const fn unit_len(_ch: char) -> usize {
50        1
51    }
52
53    /// Detects a UTF-32 BOM and returns its byte order.
54    ///
55    /// # Parameters
56    ///
57    /// - `bytes`: The byte buffer to inspect.
58    ///
59    /// # Returns
60    ///
61    /// Returns `Some(ByteOrder)` for UTF-32 BOM prefixes, or `None` otherwise.
62    #[inline]
63    pub fn detect_bom(bytes: &[u8]) -> Option<ByteOrder> {
64        match UnicodeBom::detect(bytes) {
65            Some(UnicodeBom::Utf32BigEndian) => Some(ByteOrder::BigEndian),
66            Some(UnicodeBom::Utf32LittleEndian) => {
67                Some(ByteOrder::LittleEndian)
68            }
69            _ => None,
70        }
71    }
72}
qubit_codec_text/charset/utf32.rs

qubit_codec_text/charset/
utf32.rs
