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LibHTML: Implement some basic floating point CSS value parsing

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This commit is contained in:
Andreas Kling 2019-11-18 16:54:03 +01:00
parent b0f38c1733
commit a14cc573b0
Notes: sideshowbarker 2024-07-19 11:09:26 +09:00
1 changed files with 86 additions and 7 deletions
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93
Libraries/LibHTML/Parser/CSSParser.cpp
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@ -22,13 +22,92 @@ static Optional<Color> parse_css_color(const StringView& view)
return {};
}
NonnullRefPtr<StyleValue> parse_css_value(const StringView& view)
static Optional<float> try_parse_float(const StringView& string)
{
String string(view);
char* endptr = nullptr;
long value = strtol(String(view).characters(), &endptr, 10);
if (endptr && ((!*endptr) || (endptr[0] == 'p' && endptr[1] == 'x' && endptr[2] == '\0')))
return LengthStyleValue::create(Length((float)value, Length::Type::Absolute));
const char* str = string.characters_without_null_termination();
size_t len = string.length();
size_t weight = 1;
int exp_val = 0;
float value = 0.0f;
float fraction = 0.0f;
bool has_sign = false;
bool is_negative = false;
bool is_fractional = false;
bool is_scientific = false;
if (str[0] == '-') {
is_negative = true;
has_sign = true;
}
if (str[0] == '+') {
has_sign = true;
}
for (size_t i = has_sign; i < len; i++) {
// Looks like we're about to start working on the fractional part
if (str[i] == '.') {
is_fractional = true;
continue;
}
if (str[i] == 'e' || str[i] == 'E') {
if (str[i + 1] == '-' || str[i + 1] == '+')
exp_val = atoi(str + i + 2);
else
exp_val = atoi(str + i + 1);
is_scientific = true;
continue;
}
if (str[i] < '0' || str[i] > '9' || exp_val != 0) {
return {};
continue;
}
if (is_fractional) {
fraction *= 10;
fraction += str[i] - '0';
weight *= 10;
} else {
value = value * 10;
value += str[i] - '0';
}
}
fraction /= weight;
value += fraction;
if (is_scientific) {
bool divide = exp_val < 0;
if (divide)
exp_val *= -1;
for (int i = 0; i < exp_val; i++) {
if (divide)
value /= 10;
else
value *= 10;
}
}
return is_negative ? -value : value;
}
static Optional<float> parse_number(const StringView& view)
{
if (view.length() >= 2 && view[view.length() - 2] == 'p' && view[view.length() - 1] == 'x')
return parse_number(view.substring_view(0, view.length() - 2));
return try_parse_float(view);
}
NonnullRefPtr<StyleValue> parse_css_value(const StringView& string)
{
auto number = parse_number(string);
if (number.has_value())
return LengthStyleValue::create(Length(number.value(), Length::Type::Absolute));
if (string == "inherit")
return InheritStyleValue::create();
if (string == "initial")
@ -36,7 +115,7 @@ NonnullRefPtr<StyleValue> parse_css_value(const StringView& view)
if (string == "auto")
return LengthStyleValue::create(Length());
auto color = parse_css_color(view);
auto color = parse_css_color(string);
if (color.has_value())
return ColorStyleValue::create(color.value());