/*
* Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/StringBuilder.h>
#include <AK/Utf8View.h>
#include <LibWeb/CSS/Serialize.h>
namespace Web::CSS {
// https://www.w3.org/TR/cssom-1/#escape-a-character
void escape_a_character(StringBuilder& builder, u32 character)
{
builder.append('\\');
builder.append_code_point(character);
}
// https://www.w3.org/TR/cssom-1/#escape-a-character-as-code-point
void escape_a_character_as_code_point(StringBuilder& builder, u32 character)
{
builder.appendff("\\{:x} ", character);
}
// https://www.w3.org/TR/cssom-1/#serialize-an-identifier
void serialize_an_identifier(StringBuilder& builder, StringView ident)
{
Utf8View characters { ident };
auto first_character = characters.is_empty() ? 0 : *characters.begin();
// To serialize an identifier means to create a string represented by the concatenation of,
// for each character of the identifier:
for (auto character : characters) {
// If the character is NULL (U+0000), then the REPLACEMENT CHARACTER (U+FFFD).
if (character == 0) {
builder.append_code_point(0xFFFD);
continue;
}
// If the character is in the range [\1-\1f] (U+0001 to U+001F) or is U+007F,
// then the character escaped as code point.
if ((character >= 0x0001 && character <= 0x001F) || (character == 0x007F)) {
escape_a_character_as_code_point(builder, character);
continue;
}
// If the character is the first character and is in the range [0-9] (U+0030 to U+0039),
// then the character escaped as code point.
if (builder.is_empty() && character >= '0' && character <= '9') {
escape_a_character_as_code_point(builder, character);
continue;
}
// If the character is the second character and is in the range [0-9] (U+0030 to U+0039)
// and the first character is a "-" (U+002D), then the character escaped as code point.
if (builder.length() == 1 && first_character == '-' && character >= '0' && character <= '9') {
escape_a_character_as_code_point(builder, character);
continue;
}
// If the character is the first character and is a "-" (U+002D), and there is no second
// character, then the escaped character.
if (builder.is_empty() && character == '-' && characters.length() == 1) {
escape_a_character(builder, character);
continue;
}
// If the character is not handled by one of the above rules and is greater than or equal to U+0080, is "-" (U+002D) or "_" (U+005F), or is in one of the ranges [0-9] (U+0030 to U+0039), [A-Z] (U+0041 to U+005A), or \[a-z] (U+0061 to U+007A), then the character itself.
if ((character >= 0x0080)
|| (character == '-') || (character == '_')
|| (character >= '0' && character <= '9')
|| (character >= 'A' && character <= 'Z')
|| (character >= 'a' && character <= 'z')) {
builder.append_code_point(character);
continue;
}
// Otherwise, the escaped character.
escape_a_character(builder, character);
}
}
// https://www.w3.org/TR/cssom-1/#serialize-a-string
void serialize_a_string(StringBuilder& builder, StringView string)
{
Utf8View characters { string };
// To serialize a string means to create a string represented by '"' (U+0022), followed by the result
// of applying the rules below to each character of the given string, followed by '"' (U+0022):
builder.append('"');
for (auto character : characters) {
// If the character is NULL (U+0000), then the REPLACEMENT CHARACTER (U+FFFD).
if (character == 0) {
builder.append_code_point(0xFFFD);
continue;
}
// If the character is in the range [\1-\1f] (U+0001 to U+001F) or is U+007F, the character escaped as code point.
if ((character >= 0x0001 && character <= 0x001F) || (character == 0x007F)) {
escape_a_character_as_code_point(builder, character);
continue;
}
// If the character is '"' (U+0022) or "\" (U+005C), the escaped character.
if (character == 0x0022 || character == 0x005C) {
escape_a_character(builder, character);
continue;
}
// Otherwise, the character itself.
builder.append_code_point(character);
}
builder.append('"');
}
// https://www.w3.org/TR/cssom-1/#serialize-a-url
void serialize_a_url(StringBuilder& builder, StringView url)
{
// To serialize a URL means to create a string represented by "url(",
// followed by the serialization of the URL as a string, followed by ")".
builder.append("url("sv);
serialize_a_string(builder, url);
builder.append(')');
}
// https://www.w3.org/TR/cssom-1/#serialize-a-local
void serialize_a_local(StringBuilder& builder, StringView path)
{
// To serialize a LOCAL means to create a string represented by "local(",
// followed by the serialization of the LOCAL as a string, followed by ")".
builder.append("local("sv);
serialize_a_string(builder, path);
builder.append(')');
}
// NOTE: No spec currently exists for serializing a <'unicode-range'>.
void serialize_unicode_ranges(StringBuilder& builder, Vector<Gfx::UnicodeRange> const& unicode_ranges)
{
serialize_a_comma_separated_list(builder, unicode_ranges, [](auto& builder, Gfx::UnicodeRange unicode_range) -> void {
return serialize_a_string(builder, unicode_range.to_string());
});
}
namespace {
char nth_digit(u32 value, u8 digit)
{
// This helper is used to format integers.
// nth_digit(745, 1) -> '5'
// nth_digit(745, 2) -> '4'
// nth_digit(745, 3) -> '7'
VERIFY(value < 1000);
VERIFY(digit <= 3);
VERIFY(digit > 0);
while (digit > 1) {
value /= 10;
digit--;
}
return '0' + value % 10;
}
Array<char, 4> format_to_8bit_compatible(u8 value)
{
// This function formats to the shortest string that roundtrips at 8 bits.
// As an example:
// 127 / 255 = 0.498 ± 0.001
// 128 / 255 = 0.502 ± 0.001
// But round(.5 * 255) == 128, so this function returns (note that it's only the fractional part):
// 127 -> "498"
// 128 -> "5"
u32 const three_digits = (value * 1000u + 127) / 255;
u32 const rounded_to_two_digits = (three_digits + 5) / 10 * 10;
if ((rounded_to_two_digits * 255 / 100 + 5) / 10 != value)
return { nth_digit(three_digits, 3), nth_digit(three_digits, 2), nth_digit(three_digits, 1), '\0' };
u32 const rounded_to_one_digit = (three_digits + 50) / 100 * 100;
if ((rounded_to_one_digit * 255 / 100 + 5) / 10 != value)
return { nth_digit(rounded_to_two_digits, 3), nth_digit(rounded_to_two_digits, 2), '\0', '\0' };
return { nth_digit(rounded_to_one_digit, 3), '\0', '\0', '\0' };
}
}
// https://www.w3.org/TR/css-color-4/#serializing-sRGB-values
void serialize_a_srgb_value(StringBuilder& builder, Color color)
{
// The serialized form is derived from the computed value and thus, uses either the rgb() or rgba() form
// (depending on whether the alpha is exactly 1, or not), with lowercase letters for the function name.
// NOTE: Since we use Gfx::Color, having an "alpha of 1" means its value is 255.
if (color.alpha() == 0)
builder.appendff("rgba({}, {}, {}, 0)"sv, color.red(), color.green(), color.blue());
else if (color.alpha() == 255)
builder.appendff("rgb({}, {}, {})"sv, color.red(), color.green(), color.blue());
else
builder.appendff("rgba({}, {}, {}, 0.{})"sv, color.red(), color.green(), color.blue(), format_to_8bit_compatible(color.alpha()).data());
}
String serialize_an_identifier(StringView ident)
{
StringBuilder builder;
serialize_an_identifier(builder, ident);
return MUST(builder.to_string());
}
String serialize_a_string(StringView string)
{
StringBuilder builder;
serialize_a_string(builder, string);
return MUST(builder.to_string());
}
String serialize_a_url(StringView url)
{
StringBuilder builder;
serialize_a_url(builder, url);
return MUST(builder.to_string());
}
String serialize_a_srgb_value(Color color)
{
StringBuilder builder;
serialize_a_srgb_value(builder, color);
return MUST(builder.to_string());
}
}