LibWeb: Rename directory LibHTML => LibWeb

Let's rename this to LibWeb since it aims to provide more parts of the
web platform than just HTML. :^)

Libraries/LibWeb/Parser/CSSParser.cpp

@@ -0,0 +1,637 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/HashMap.h>
+#include <LibWeb/CSS/PropertyID.h>
+#include <LibWeb/CSS/StyleSheet.h>
+#include <LibWeb/Parser/CSSParser.h>
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#define PARSE_ASSERT(x)                                                   \
+    if (!(x)) {                                                           \
+        dbg() << "CSS PARSER ASSERTION FAILED: " << #x;                   \
+        dbg() << "At character# " << index << " in CSS: _" << css << "_"; \
+        ASSERT_NOT_REACHED();                                             \
+    }
+
+namespace Web {
+
+static Optional<Color> parse_css_color(const StringView& view)
+{
+    auto color = Color::from_string(view);
+    if (color.has_value())
+        return color;
+
+    return {};
+}
+
+static Optional<float> try_parse_float(const StringView& string)
+{
+    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")
+        return InitialStyleValue::create();
+    if (string == "auto")
+        return LengthStyleValue::create(Length());
+
+    auto color = parse_css_color(string);
+    if (color.has_value())
+        return ColorStyleValue::create(color.value());
+
+    if (string == "-libhtml-link")
+        return IdentifierStyleValue::create(CSS::ValueID::VendorSpecificLink);
+
+    return StringStyleValue::create(string);
+}
+
+class CSSParser {
+public:
+    CSSParser(const StringView& input)
+        : css(input)
+    {
+    }
+
+    bool next_is(const char* str) const
+    {
+        size_t len = strlen(str);
+        for (size_t i = 0; i < len; ++i) {
+            if (peek(i) != str[i])
+                return false;
+        }
+        return true;
+    }
+
+    char peek(size_t offset = 0) const
+    {
+        if ((index + offset) < css.length())
+            return css[index + offset];
+        return 0;
+    }
+
+    char consume_specific(char ch)
+    {
+        if (peek() != ch) {
+            dbg() << "peek() != '" << ch << "'";
+        }
+        PARSE_ASSERT(peek() == ch);
+        PARSE_ASSERT(index < css.length());
+        ++index;
+        return ch;
+    }
+
+    char consume_one()
+    {
+        PARSE_ASSERT(index < css.length());
+        return css[index++];
+    };
+
+    bool consume_whitespace_or_comments()
+    {
+        size_t original_index = index;
+        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;
+        }
+        return original_index != index;
+    }
+
+    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::SimpleSelector> parse_simple_selector()
+    {
+        if (consume_whitespace_or_comments())
+            return {};
+
+        if (peek() == '{' || peek() == ',' || is_combinator(peek()))
+            return {};
+
+        Selector::SimpleSelector::Type type;
+
+        if (peek() == '*') {
+            type = Selector::SimpleSelector::Type::Universal;
+            consume_one();
+            return Selector::SimpleSelector {
+                type,
+                Selector::SimpleSelector::PseudoClass::None,
+                String(),
+                Selector::SimpleSelector::AttributeMatchType::None,
+                String(),
+                String()
+            };
+        }
+
+        if (peek() == '.') {
+            type = Selector::SimpleSelector::Type::Class;
+            consume_one();
+        } else if (peek() == '#') {
+            type = Selector::SimpleSelector::Type::Id;
+            consume_one();
+        } else if (isalpha(peek())) {
+            type = Selector::SimpleSelector::Type::TagName;
+        } else {
+            type = Selector::SimpleSelector::Type::Universal;
+        }
+
+        if (type != Selector::SimpleSelector::Type::Universal) {
+            while (is_valid_selector_char(peek()))
+                buffer.append(consume_one());
+            PARSE_ASSERT(!buffer.is_null());
+        }
+
+        Selector::SimpleSelector simple_selector {
+            type,
+            Selector::SimpleSelector::PseudoClass::None,
+            String::copy(buffer),
+            Selector::SimpleSelector::AttributeMatchType::None,
+            String(),
+            String()
+        };
+        buffer.clear();
+
+        if (peek() == '[') {
+            Selector::SimpleSelector::AttributeMatchType attribute_match_type = Selector::SimpleSelector::AttributeMatchType::HasAttribute;
+            String attribute_name;
+            String attribute_value;
+            bool in_value = false;
+            consume_specific('[');
+            char expected_end_of_attribute_selector = ']';
+            while (peek() != expected_end_of_attribute_selector) {
+                char ch = consume_one();
+                if (ch == '=') {
+                    attribute_match_type = Selector::SimpleSelector::AttributeMatchType::ExactValueMatch;
+                    attribute_name = String::copy(buffer);
+                    buffer.clear();
+                    in_value = true;
+                    consume_whitespace_or_comments();
+                    if (peek() == '\'') {
+                        expected_end_of_attribute_selector = '\'';
+                        consume_one();
+                    } else if (peek() == '"') {
+                        expected_end_of_attribute_selector = '"';
+                        consume_one();
+                    }
+                    continue;
+                }
+                buffer.append(ch);
+            }
+            if (in_value)
+                attribute_value = String::copy(buffer);
+            else
+                attribute_name = String::copy(buffer);
+            buffer.clear();
+            simple_selector.attribute_match_type = attribute_match_type;
+            simple_selector.attribute_name = attribute_name;
+            simple_selector.attribute_value = attribute_value;
+            if (expected_end_of_attribute_selector != ']')
+                consume_specific(expected_end_of_attribute_selector);
+            consume_whitespace_or_comments();
+            consume_specific(']');
+        }
+
+        if (peek() == ':') {
+            // FIXME: Implement pseudo elements.
+            [[maybe_unused]] bool is_pseudo_element = false;
+            consume_one();
+            if (peek() == ':') {
+                is_pseudo_element = true;
+                consume_one();
+            }
+            if (next_is("not")) {
+                buffer.append(consume_one());
+                buffer.append(consume_one());
+                buffer.append(consume_one());
+                buffer.append(consume_specific('('));
+                while (peek() != ')')
+                    buffer.append(consume_one());
+                buffer.append(consume_specific(')'));
+            } else {
+                while (is_valid_selector_char(peek()))
+                    buffer.append(consume_one());
+            }
+
+            auto pseudo_name = String::copy(buffer);
+            buffer.clear();
+
+            if (pseudo_name == "link")
+                simple_selector.pseudo_class = Selector::SimpleSelector::PseudoClass::Link;
+            else if (pseudo_name == "hover")
+                simple_selector.pseudo_class = Selector::SimpleSelector::PseudoClass::Hover;
+            else if (pseudo_name == "first-child")
+                simple_selector.pseudo_class = Selector::SimpleSelector::PseudoClass::FirstChild;
+            else if (pseudo_name == "last-child")
+                simple_selector.pseudo_class = Selector::SimpleSelector::PseudoClass::LastChild;
+            else if (pseudo_name == "only-child")
+                simple_selector.pseudo_class = Selector::SimpleSelector::PseudoClass::OnlyChild;
+            else if (pseudo_name == "empty")
+                simple_selector.pseudo_class = Selector::SimpleSelector::PseudoClass::Empty;
+        }
+
+        return simple_selector;
+    }
+
+    Optional<Selector::ComplexSelector> parse_complex_selector()
+    {
+        auto relation = Selector::ComplexSelector::Relation::Descendant;
+
+        if (peek() == '{' || peek() == ',')
+            return {};
+
+        if (is_combinator(peek())) {
+            switch (peek()) {
+            case '>':
+                relation = Selector::ComplexSelector::Relation::ImmediateChild;
+                break;
+            case '+':
+                relation = Selector::ComplexSelector::Relation::AdjacentSibling;
+                break;
+            case '~':
+                relation = Selector::ComplexSelector::Relation::GeneralSibling;
+                break;
+            }
+            consume_one();
+            consume_whitespace_or_comments();
+        }
+
+        consume_whitespace_or_comments();
+
+        Vector<Selector::SimpleSelector> simple_selectors;
+        for (;;) {
+            auto component = parse_simple_selector();
+            if (!component.has_value())
+                break;
+            simple_selectors.append(component.value());
+            // If this assert triggers, we're most likely up to no good.
+            PARSE_ASSERT(simple_selectors.size() < 100);
+        }
+
+        return Selector::ComplexSelector { relation, move(simple_selectors) };
+    }
+
+    void parse_selector()
+    {
+        Vector<Selector::ComplexSelector> complex_selectors;
+
+        for (;;) {
+            auto complex_selector = parse_complex_selector();
+            if (complex_selector.has_value())
+                complex_selectors.append(complex_selector.value());
+            consume_whitespace_or_comments();
+            if (peek() == ',' || peek() == '{')
+                break;
+        }
+
+        if (complex_selectors.is_empty())
+            return;
+        complex_selectors.first().relation = Selector::ComplexSelector::Relation::None;
+
+        current_rule.selectors.append(Selector(move(complex_selectors)));
+    };
+
+    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 != ';' && ch != '}';
+    }
+
+    struct ValueAndImportant {
+        String value;
+        bool important { false };
+    };
+
+    ValueAndImportant consume_css_value()
+    {
+        buffer.clear();
+
+        int paren_nesting_level = 0;
+        bool important = false;
+
+        for (;;) {
+            char ch = peek();
+            if (ch == '(') {
+                ++paren_nesting_level;
+                buffer.append(consume_one());
+                continue;
+            }
+            if (ch == ')') {
+                PARSE_ASSERT(paren_nesting_level > 0);
+                --paren_nesting_level;
+                buffer.append(consume_one());
+                continue;
+            }
+            if (paren_nesting_level > 0) {
+                buffer.append(consume_one());
+                continue;
+            }
+            if (next_is("!important")) {
+                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');
+                important = true;
+                continue;
+            }
+            if (next_is("/*")) {
+                consume_whitespace_or_comments();
+                continue;
+            }
+            if (!ch)
+                break;
+            if (ch == '}')
+                break;
+            if (ch == ';')
+                break;
+            buffer.append(consume_one());
+        }
+
+        // Remove trailing whitespace.
+        while (!buffer.is_empty() && isspace(buffer.last()))
+            buffer.take_last();
+
+        auto string = String::copy(buffer);
+        buffer.clear();
+
+        return { string, important };
+    }
+
+    Optional<StyleProperty> parse_property()
+    {
+        consume_whitespace_or_comments();
+        if (peek() == ';') {
+            consume_one();
+            return {};
+        }
+        if (peek() == '}')
+            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();
+
+        auto [property_value, important] = consume_css_value();
+
+        consume_whitespace_or_comments();
+
+        if (peek() && peek() != '}')
+            consume_specific(';');
+
+        auto property_id = CSS::property_id_from_string(property_name);
+        return StyleProperty { property_id, parse_css_value(property_value), 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 @-rules for now.
+        if (peek() == '@') {
+            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();
+    }
+
+    RefPtr<StyleSheet> parse_sheet()
+    {
+        while (index < css.length()) {
+            parse_rule();
+        }
+
+        return StyleSheet::create(move(rules));
+    }
+
+    RefPtr<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;
+
+    size_t index = 0;
+
+    StringView css;
+};
+
+RefPtr<StyleSheet> parse_css(const StringView& css)
+{
+    CSSParser parser(css);
+    return parser.parse_sheet();
+}
+
+RefPtr<StyleDeclaration> parse_css_declaration(const StringView& css)
+{
+    CSSParser parser(css);
+    return parser.parse_standalone_declaration();
+}
+
+}

Libraries/LibWeb/Parser/CSSParser.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/NonnullRefPtr.h>
+#include <LibWeb/CSS/StyleSheet.h>
+
+namespace Web {
+
+RefPtr<StyleSheet> parse_css(const StringView&);
+RefPtr<StyleDeclaration> parse_css_declaration(const StringView&);
+NonnullRefPtr<StyleValue> parse_css_value(const StringView&);
+
+}

Libraries/LibWeb/Parser/HTMLParser.cpp

@@ -0,0 +1,384 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/Function.h>
+#include <AK/NonnullRefPtrVector.h>
+#include <AK/StringBuilder.h>
+#include <LibWeb/DOM/Comment.h>
+#include <LibWeb/DOM/DocumentFragment.h>
+#include <LibWeb/DOM/DocumentType.h>
+#include <LibWeb/DOM/Element.h>
+#include <LibWeb/DOM/ElementFactory.h>
+#include <LibWeb/DOM/Text.h>
+#include <LibWeb/Parser/HTMLParser.h>
+#include <ctype.h>
+#include <stdio.h>
+
+namespace Web {
+
+static bool is_valid_in_attribute_name(char ch)
+{
+    return isalnum(ch) || ch == '_' || ch == '-';
+}
+
+static bool is_self_closing_tag(const StringView& tag_name)
+{
+    return tag_name == "area"
+        || tag_name == "base"
+        || tag_name == "br"
+        || tag_name == "col"
+        || tag_name == "embed"
+        || tag_name == "hr"
+        || tag_name == "img"
+        || tag_name == "input"
+        || tag_name == "link"
+        || tag_name == "meta"
+        || tag_name == "param"
+        || tag_name == "source"
+        || tag_name == "track"
+        || tag_name == "wbr";
+}
+
+static bool parse_html_document(const StringView& html, Document& document, ParentNode& root)
+{
+    NonnullRefPtrVector<ParentNode> node_stack;
+    node_stack.append(root);
+
+    enum class State {
+        Free = 0,
+        BeforeTagName,
+        InTagName,
+        InDoctype,
+        InComment,
+        InAttributeList,
+        InAttributeName,
+        BeforeAttributeValue,
+        InAttributeValueNoQuote,
+        InAttributeValueSingleQuote,
+        InAttributeValueDoubleQuote,
+    };
+
+    auto state = State::Free;
+
+    StringBuilder text_buffer;
+
+    Vector<char, 32> tag_name_buffer;
+
+    Vector<Attribute> attributes;
+    Vector<char, 256> attribute_name_buffer;
+    Vector<char, 256> attribute_value_buffer;
+
+    bool is_slash_tag = false;
+    bool is_exclamation_tag = false;
+
+    auto move_to_state = [&](State new_state) {
+        if (new_state == State::BeforeTagName) {
+            is_slash_tag = false;
+            is_exclamation_tag = false;
+            tag_name_buffer.clear();
+            attributes.clear();
+        }
+        if (new_state == State::InAttributeName)
+            attribute_name_buffer.clear();
+        if (new_state == State::BeforeAttributeValue)
+            attribute_value_buffer.clear();
+        if (state == State::Free && !text_buffer.string_view().is_empty()) {
+            auto text_node = adopt(*new Text(document, text_buffer.to_string()));
+            node_stack.last().append_child(text_node, false);
+        }
+        state = new_state;
+        text_buffer.clear();
+    };
+
+    auto close_tag = [&] {
+        if (node_stack.size() > 1)
+            node_stack.take_last();
+    };
+
+    auto open_tag = [&] {
+        auto new_element = create_element(document, String::copy(tag_name_buffer));
+        tag_name_buffer.clear();
+        new_element->set_attributes(move(attributes));
+        node_stack.append(new_element);
+        if (node_stack.size() != 1)
+            node_stack[node_stack.size() - 2].append_child(new_element, false);
+
+        if (is_self_closing_tag(new_element->tag_name()))
+            close_tag();
+    };
+
+    auto commit_doctype = [&] {
+        node_stack.last().append_child(adopt(*new DocumentType(document)), false);
+    };
+
+    auto commit_comment = [&] {
+        node_stack.last().append_child(adopt(*new Comment(document, text_buffer.to_string())), false);
+    };
+
+    auto commit_tag = [&] {
+        if (is_slash_tag)
+            close_tag();
+        else
+            open_tag();
+    };
+
+    auto commit_attribute = [&] {
+        if (!attribute_name_buffer.is_empty()) {
+            auto name = String::copy(attribute_name_buffer);
+            String value;
+            if (attribute_value_buffer.is_empty())
+                value = String::empty();
+            else
+                value = String::copy(attribute_value_buffer);
+            attributes.empend(name, value);
+        }
+    };
+
+    for (size_t i = 0; i < html.length(); ++i) {
+        auto peek = [&](size_t offset) -> char {
+            if (i + offset >= html.length())
+                return '\0';
+            return html[i + offset];
+        };
+        char ch = html[i];
+        switch (state) {
+        case State::Free:
+            if (ch == '<') {
+                is_slash_tag = false;
+                move_to_state(State::BeforeTagName);
+                break;
+            }
+            if (ch != '&') {
+                text_buffer.append(ch);
+            } else {
+                struct Escape {
+                    const char* code;
+                    const char* value;
+                };
+                static Escape escapes[] = {
+                    { "&lt;", "<" },
+                    { "&gt;", ">" },
+                    { "&amp;", "&" },
+                    { "&mdash;", "-" },
+                };
+                auto rest_of_html = html.substring_view(i, html.length() - i);
+                bool found = false;
+                for (auto& escape : escapes) {
+                    if (rest_of_html.starts_with(escape.code)) {
+                        text_buffer.append(escape.value);
+                        found = true;
+                        i += strlen(escape.code) - 1;
+                        break;
+                    }
+                }
+                if (!found)
+                    dbg() << "Unhandled escape sequence";
+            }
+            break;
+        case State::BeforeTagName:
+            if (ch == '/') {
+                is_slash_tag = true;
+                break;
+            }
+            if (ch == '!') {
+                if (toupper(peek(1)) == 'D'
+                    && toupper(peek(2)) == 'O'
+                    && toupper(peek(3)) == 'C'
+                    && toupper(peek(4)) == 'T'
+                    && toupper(peek(5)) == 'Y'
+                    && toupper(peek(6)) == 'P'
+                    && toupper(peek(7)) == 'E') {
+                    i += 7;
+                    move_to_state(State::InDoctype);
+                    break;
+                }
+                if (peek(1) == '-' && peek(2) == '-') {
+                    i += 2;
+                    move_to_state(State::InComment);
+                    break;
+                }
+                break;
+            }
+            if (ch == '>') {
+                move_to_state(State::Free);
+                break;
+            }
+            if (!isalpha(ch))
+                break;
+            move_to_state(State::InTagName);
+            [[fallthrough]];
+        case State::InTagName:
+            if (isspace(ch)) {
+                move_to_state(State::InAttributeList);
+                break;
+            }
+            if (ch == '>') {
+                commit_tag();
+                move_to_state(State::Free);
+                break;
+            }
+            tag_name_buffer.append(ch);
+            break;
+        case State::InDoctype:
+            if (ch == '>') {
+                commit_doctype();
+                move_to_state(State::Free);
+                break;
+            }
+            break;
+        case State::InComment:
+            if (ch == '-' && peek(1) == '-' && peek(2) == '>') {
+                commit_comment();
+                i += 2;
+                move_to_state(State::Free);
+                break;
+            }
+            text_buffer.append(ch);
+            break;
+        case State::InAttributeList:
+            if (ch == '>') {
+                commit_tag();
+                move_to_state(State::Free);
+                break;
+            }
+            if (!isalpha(ch))
+                break;
+            move_to_state(State::InAttributeName);
+            [[fallthrough]];
+        case State::InAttributeName:
+            if (is_valid_in_attribute_name(ch)) {
+                attribute_name_buffer.append(ch);
+                break;
+            }
+            if (isspace(ch)) {
+                commit_attribute();
+                break;
+            }
+
+            if (ch == '>') {
+                commit_attribute();
+                commit_tag();
+                move_to_state(State::Free);
+                break;
+            }
+
+            if (ch == '=') {
+                move_to_state(State::BeforeAttributeValue);
+                break;
+            }
+            break;
+        case State::BeforeAttributeValue:
+            if (ch == '\'') {
+                move_to_state(State::InAttributeValueSingleQuote);
+                break;
+            }
+            if (ch == '"') {
+                move_to_state(State::InAttributeValueDoubleQuote);
+                break;
+            }
+            if (ch == '>') {
+                commit_tag();
+                move_to_state(State::Free);
+                break;
+            }
+            if (isspace(ch)) {
+                commit_attribute();
+                move_to_state(State::InAttributeList);
+                break;
+            }
+            move_to_state(State::InAttributeValueNoQuote);
+            [[fallthrough]];
+        case State::InAttributeValueNoQuote:
+            if (isspace(ch)) {
+                commit_attribute();
+                move_to_state(State::InAttributeList);
+                break;
+            }
+            if (ch == '>') {
+                commit_attribute();
+                commit_tag();
+                move_to_state(State::Free);
+                break;
+            }
+            attribute_value_buffer.append(ch);
+            break;
+        case State::InAttributeValueSingleQuote:
+            if (ch == '\'') {
+                commit_attribute();
+                move_to_state(State::InAttributeList);
+                break;
+            }
+            attribute_value_buffer.append(ch);
+            break;
+        case State::InAttributeValueDoubleQuote:
+            if (ch == '"') {
+                commit_attribute();
+                move_to_state(State::InAttributeList);
+                break;
+            }
+            attribute_value_buffer.append(ch);
+            break;
+        default:
+            fprintf(stderr, "Unhandled state %d\n", (int)state);
+            ASSERT_NOT_REACHED();
+        }
+    }
+
+    return true;
+}
+
+RefPtr<DocumentFragment> parse_html_fragment(Document& document, const StringView& html)
+{
+    auto fragment = adopt(*new DocumentFragment(document));
+    if (!parse_html_document(html, document, *fragment))
+        return nullptr;
+    return fragment;
+}
+
+RefPtr<Document> parse_html_document(const StringView& html, const URL& url)
+{
+    auto document = adopt(*new Document);
+    document->set_url(url);
+    document->set_source(html);
+
+    if (!parse_html_document(html, *document, *document))
+        return nullptr;
+
+    document->fixup();
+
+    Function<void(Node&)> fire_insertion_callbacks = [&](Node& node) {
+        for (auto* child = node.first_child(); child; child = child->next_sibling()) {
+            fire_insertion_callbacks(*child);
+        }
+        if (node.parent())
+            node.inserted_into(*node.parent());
+    };
+    fire_insertion_callbacks(document);
+
+    return document;
+}
+
+}

Libraries/LibWeb/Parser/HTMLParser.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/NonnullRefPtr.h>
+#include <LibWeb/DOM/Document.h>
+
+namespace Web {
+
+class DocumentFragment;
+
+RefPtr<Document> parse_html_document(const StringView&, const URL& = URL());
+RefPtr<DocumentFragment> parse_html_fragment(Document&, const StringView&);
+
+}