ladybird/Libraries/LibHTML/Parser/CSSParser.cpp

428 lines
13 KiB
C++

#include <AK/HashMap.h>
#include <LibHTML/CSS/StyleSheet.h>
#include <LibHTML/Parser/CSSParser.h>
#include <ctype.h>
#include <stdio.h>
#define PARSE_ASSERT(x) \
if (!(x)) { \
dbg() << "CSS PARSER ASSERTION FAILED: " << #x; \
dbg() << "At character# " << index << " in CSS: _" << css << "_"; \
ASSERT_NOT_REACHED(); \
}
static Optional<Color> parse_css_color(const StringView& view)
{
auto color = Color::from_string(view);
if (color.has_value())
return color;
// FIXME: Parse all valid color strings :^)
return {};
}
NonnullRefPtr<StyleValue> parse_css_value(const StringView& view)
{
String string(view);
bool ok;
int as_int = string.to_int(ok);
if (ok)
return LengthStyleValue::create(Length(as_int, Length::Type::Absolute));
unsigned as_uint = string.to_uint(ok);
if (ok)
return LengthStyleValue::create(Length(as_uint, Length::Type::Absolute));
if (string == "inherit")
return InheritStyleValue::create();
if (string == "initial")
return InitialStyleValue::create();
if (string == "auto")
return LengthStyleValue::create(Length());
auto color = parse_css_color(view);
if (color.has_value())
return ColorStyleValue::create(color.value());
if (string == "-libhtml-link")
return IdentifierStyleValue::create(CSS::ValueID::VendorSpecificLink);
return StringStyleValue::create(string);
}
static CSS::PropertyID parse_css_property_id(const StringView& string)
{
static HashMap<String, CSS::PropertyID> map;
if (map.is_empty()) {
map.set("background-color", CSS::PropertyID::BackgroundColor);
map.set("border-bottom-style", CSS::PropertyID::BorderBottomStyle);
map.set("border-bottom-width", CSS::PropertyID::BorderBottomWidth);
map.set("border-collapse", CSS::PropertyID::BorderCollapse);
map.set("border-left-style", CSS::PropertyID::BorderLeftStyle);
map.set("border-left-width", CSS::PropertyID::BorderLeftWidth);
map.set("border-right-style", CSS::PropertyID::BorderRightStyle);
map.set("border-right-width", CSS::PropertyID::BorderRightWidth);
map.set("border-spacing", CSS::PropertyID::BorderSpacing);
map.set("border-top-style", CSS::PropertyID::BorderTopStyle);
map.set("border-top-width", CSS::PropertyID::BorderTopWidth);
map.set("color", CSS::PropertyID::Color);
map.set("display", CSS::PropertyID::Display);
map.set("font-family", CSS::PropertyID::FontFamily);
map.set("font-size", CSS::PropertyID::FontSize);
map.set("font-style", CSS::PropertyID::FontStyle);
map.set("font-variant", CSS::PropertyID::FontVariant);
map.set("font-weight", CSS::PropertyID::FontWeight);
map.set("height", CSS::PropertyID::Height);
map.set("letter-spacing", CSS::PropertyID::LetterSpacing);
map.set("line-height", CSS::PropertyID::LineHeight);
map.set("list-style", CSS::PropertyID::ListStyle);
map.set("list-style-image", CSS::PropertyID::ListStyleImage);
map.set("list-style-position", CSS::PropertyID::ListStylePosition);
map.set("list-style-type", CSS::PropertyID::ListStyleType);
map.set("margin-bottom", CSS::PropertyID::MarginBottom);
map.set("margin-left", CSS::PropertyID::MarginLeft);
map.set("margin-right", CSS::PropertyID::MarginRight);
map.set("margin-top", CSS::PropertyID::MarginTop);
map.set("padding-bottom", CSS::PropertyID::PaddingBottom);
map.set("padding-left", CSS::PropertyID::PaddingLeft);
map.set("padding-right", CSS::PropertyID::PaddingRight);
map.set("padding-top", CSS::PropertyID::PaddingTop);
map.set("text-align", CSS::PropertyID::TextAlign);
map.set("text-decoration", CSS::PropertyID::TextDecoration);
map.set("text-indent", CSS::PropertyID::TextIndent);
map.set("text-transform", CSS::PropertyID::TextTransform);
map.set("visibility", CSS::PropertyID::Visibility);
map.set("white-space", CSS::PropertyID::WhiteSpace);
map.set("width", CSS::PropertyID::Width);
map.set("word-spacing", CSS::PropertyID::WordSpacing);
}
return map.get(string).value_or(CSS::PropertyID::Invalid);
}
class CSSParser {
public:
CSSParser(const StringView& input)
: css(input)
{
}
bool next_is(const char* str) const
{
int len = strlen(str);
for (int i = 0; i < len; ++i) {
if (peek(i) != str[i])
return false;
}
return true;
}
char peek(int offset = 0) const
{
if ((index + offset) < css.length())
return css[index + offset];
return 0;
}
char consume_specific(char ch)
{
PARSE_ASSERT(peek() == ch);
PARSE_ASSERT(index < css.length());
++index;
return ch;
}
char consume_one()
{
PARSE_ASSERT(index < css.length());
return css[index++];
};
void consume_whitespace_or_comments()
{
bool in_comment = false;
for (; index < css.length(); ++index) {
char ch = peek();
if (isspace(ch))
continue;
if (!in_comment && ch == '/' && peek(1) == '*') {
in_comment = true;
++index;
continue;
}
if (in_comment && ch == '*' && peek(1) == '/') {
in_comment = false;
++index;
continue;
}
if (in_comment)
continue;
break;
}
}
bool is_valid_selector_char(char ch) const
{
return isalnum(ch) || ch == '-' || ch == '_' || ch == '(' || ch == ')' || ch == '@';
}
bool is_combinator(char ch) const
{
return ch == '~' || ch == '>' || ch == '+';
}
Optional<Selector::Component> parse_selector_component()
{
consume_whitespace_or_comments();
Selector::Component::Type type;
Selector::Component::Relation relation = Selector::Component::Relation::Descendant;
if (peek() == '{')
return {};
if (is_combinator(peek())) {
switch (peek()) {
case '>':
relation = Selector::Component::Relation::ImmediateChild;
break;
case '+':
relation = Selector::Component::Relation::AdjacentSibling;
break;
case '~':
relation = Selector::Component::Relation::GeneralSibling;
break;
}
consume_one();
consume_whitespace_or_comments();
}
if (peek() == '.') {
type = Selector::Component::Type::Class;
consume_one();
} else if (peek() == '#') {
type = Selector::Component::Type::Id;
consume_one();
} else {
type = Selector::Component::Type::TagName;
}
while (is_valid_selector_char(peek()))
buffer.append(consume_one());
PARSE_ASSERT(!buffer.is_null());
Selector::Component component { type, Selector::Component::PseudoClass::None, relation, String::copy(buffer) };
buffer.clear();
if (peek() == '[') {
// FIXME: Implement attribute selectors.
while (peek() != ']') {
consume_one();
}
consume_one();
}
if (peek() == ':') {
// FIXME: Implement pseudo elements.
[[maybe_unused]] bool is_pseudo_element = false;
consume_one();
if (peek() == ':') {
is_pseudo_element = true;
consume_one();
}
while (is_valid_selector_char(peek()))
buffer.append(consume_one());
auto pseudo_name = String::copy(buffer);
buffer.clear();
if (pseudo_name == "link")
component.pseudo_class = Selector::Component::PseudoClass::Link;
else if (pseudo_name == "hover")
component.pseudo_class = Selector::Component::PseudoClass::Hover;
}
return component;
}
void parse_selector()
{
Vector<Selector::Component> components;
for (;;) {
auto component = parse_selector_component();
if (component.has_value())
components.append(component.value());
consume_whitespace_or_comments();
if (peek() == ',' || peek() == '{')
break;
}
if (components.is_empty())
return;
components.first().relation = Selector::Component::Relation::None;
current_rule.selectors.append(Selector(move(components)));
};
void parse_selector_list()
{
for (;;) {
parse_selector();
consume_whitespace_or_comments();
if (peek() == ',') {
consume_one();
continue;
}
if (peek() == '{')
break;
}
}
bool is_valid_property_name_char(char ch) const
{
return ch && !isspace(ch) && ch != ':';
}
bool is_valid_property_value_char(char ch) const
{
return ch && ch != '!' && ch != ';';
}
Optional<StyleProperty> parse_property()
{
consume_whitespace_or_comments();
if (peek() == ';') {
consume_one();
return {};
}
buffer.clear();
while (is_valid_property_name_char(peek()))
buffer.append(consume_one());
auto property_name = String::copy(buffer);
buffer.clear();
consume_whitespace_or_comments();
consume_specific(':');
consume_whitespace_or_comments();
while (is_valid_property_value_char(peek()))
buffer.append(consume_one());
// Remove trailing whitespace.
while (!buffer.is_empty() && isspace(buffer.last()))
buffer.take_last();
auto property_value = String::copy(buffer);
buffer.clear();
consume_whitespace_or_comments();
bool is_important = false;
if (peek() == '!') {
consume_specific('!');
consume_specific('i');
consume_specific('m');
consume_specific('p');
consume_specific('o');
consume_specific('r');
consume_specific('t');
consume_specific('a');
consume_specific('n');
consume_specific('t');
consume_whitespace_or_comments();
is_important = true;
}
if (peek() && peek() != '}')
consume_specific(';');
return StyleProperty { parse_css_property_id(property_name), parse_css_value(property_value), is_important };
}
void parse_declaration()
{
for (;;) {
auto property = parse_property();
if (property.has_value())
current_rule.properties.append(property.value());
consume_whitespace_or_comments();
if (peek() == '}')
break;
}
}
void parse_rule()
{
consume_whitespace_or_comments();
if (index >= css.length())
return;
// FIXME: We ignore @media rules for now.
if (next_is("@media")) {
while (peek() != '{')
consume_one();
int level = 0;
for (;;) {
auto ch = consume_one();
if (ch == '{') {
++level;
} else if (ch == '}') {
--level;
if (level == 0)
break;
}
}
consume_whitespace_or_comments();
return;
}
parse_selector_list();
consume_specific('{');
parse_declaration();
consume_specific('}');
rules.append(StyleRule::create(move(current_rule.selectors), StyleDeclaration::create(move(current_rule.properties))));
consume_whitespace_or_comments();
}
NonnullRefPtr<StyleSheet> parse_sheet()
{
while (index < css.length()) {
parse_rule();
}
return StyleSheet::create(move(rules));
}
NonnullRefPtr<StyleDeclaration> parse_standalone_declaration()
{
consume_whitespace_or_comments();
for (;;) {
auto property = parse_property();
if (property.has_value())
current_rule.properties.append(property.value());
consume_whitespace_or_comments();
if (!peek())
break;
}
return StyleDeclaration::create(move(current_rule.properties));
}
private:
NonnullRefPtrVector<StyleRule> rules;
struct CurrentRule {
Vector<Selector> selectors;
Vector<StyleProperty> properties;
};
CurrentRule current_rule;
Vector<char> buffer;
int index = 0;
StringView css;
};
NonnullRefPtr<StyleSheet> parse_css(const StringView& css)
{
CSSParser parser(css);
return parser.parse_sheet();
}
NonnullRefPtr<StyleDeclaration> parse_css_declaration(const StringView& css)
{
CSSParser parser(css);
return parser.parse_standalone_declaration();
}