jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2022, Linus Groh <linusg@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <AK/CharacterTypes.h>
8#include <LibWeb/Infra/ByteSequences.h>
9
10namespace Web::Infra {
11
12// https://infra.spec.whatwg.org/#byte-lowercase
13void byte_lowercase(ByteBuffer& bytes)
14{
15 // To byte-lowercase a byte sequence, increase each byte it contains, in the range 0x41 (A) to 0x5A (Z), inclusive, by 0x20.
16 for (size_t i = 0; i < bytes.size(); ++i)
17 bytes[i] = to_ascii_lowercase(bytes[i]);
18}
19
20// https://infra.spec.whatwg.org/#byte-uppercase
21void byte_uppercase(ByteBuffer& bytes)
22{
23 // To byte-uppercase a byte sequence, subtract each byte it contains, in the range 0x61 (a) to 0x7A (z), inclusive, by 0x20.
24 for (size_t i = 0; i < bytes.size(); ++i)
25 bytes[i] = to_ascii_uppercase(bytes[i]);
26}
27
28// https://infra.spec.whatwg.org/#byte-sequence-starts-with
29bool is_prefix_of(ReadonlyBytes potential_prefix, ReadonlyBytes input)
30{
31 // "input starts with potentialPrefix" can be used as a synonym for "potentialPrefix is a prefix of input".
32 return input.starts_with(potential_prefix);
33}
34
35// https://infra.spec.whatwg.org/#byte-less-than
36bool is_byte_less_than(ReadonlyBytes a, ReadonlyBytes b)
37{
38 // 1. If b is a prefix of a, then return false.
39 if (is_prefix_of(b, a))
40 return false;
41
42 // 2. If a is a prefix of b, then return true.
43 if (is_prefix_of(a, b))
44 return true;
45
46 // 3. Let n be the smallest index such that the nth byte of a is different from the nth byte of b.
47 // (There has to be such an index, since neither byte sequence is a prefix of the other.)
48 // 4. If the nth byte of a is less than the nth byte of b, then return true.
49 // 5. Return false.
50 for (size_t i = 0; i < a.size(); ++i) {
51 if (a[i] != b[i])
52 return a[i] < b[i];
53 }
54 VERIFY_NOT_REACHED();
55}
56
57}