LibWeb: Implement DOMTokenList for managing space-separated tokens lists

DOMTokenList is used as the return type of, e.g., the Element.classList
property.

1 files changed, 258 insertions, 0 deletions

diff --git a/Userland/Libraries/LibWeb/DOM/DOMTokenList.cpp b/Userland/Libraries/LibWeb/DOM/DOMTokenList.cpp
new file mode 100644
index 0000000000..838f933ca1
--- /dev/null
+++ b/Userland/Libraries/LibWeb/DOM/DOMTokenList.cpp
@@ -0,0 +1,258 @@
+/*
+ * Copyright (c) 2021, Tim Flynn <trflynn89@pm.me>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/CharacterTypes.h>
+#include <AK/StringBuilder.h>
+#include <LibWeb/DOM/DOMException.h>
+#include <LibWeb/DOM/DOMTokenList.h>
+#include <LibWeb/DOM/Element.h>
+
+namespace {
+
+// https://infra.spec.whatwg.org/#set-append
+inline void append_to_ordered_set(Vector<String>& set, String item)
+{
+    if (!set.contains_slow(item))
+        set.append(move(item));
+}
+
+// https://infra.spec.whatwg.org/#list-remove
+inline void remove_from_ordered_set(Vector<String>& set, StringView item)
+{
+    set.remove_first_matching([&](auto const& value) { return value == item; });
+}
+
+// https://infra.spec.whatwg.org/#set-replace
+inline void replace_in_ordered_set(Vector<String>& set, StringView item, String replacement)
+{
+    auto item_index = set.find_first_index(item);
+    VERIFY(item_index.has_value());
+
+    auto replacement_index = set.find_first_index(replacement);
+    if (!replacement_index.has_value()) {
+        set[*item_index] = move(replacement);
+        return;
+    }
+
+    auto index_to_set = min(*item_index, *replacement_index);
+    auto index_to_remove = max(*item_index, *replacement_index);
+    if (index_to_set == index_to_remove)
+        return;
+
+    set[index_to_set] = move(replacement);
+    set.remove(index_to_remove);
+}
+
+}
+
+namespace Web::DOM {
+
+NonnullRefPtr<DOMTokenList> DOMTokenList::create(Element const& associated_element, FlyString associated_attribute)
+{
+    return adopt_ref(*new DOMTokenList(associated_element, move(associated_attribute)));
+}
+
+// https://dom.spec.whatwg.org/#ref-for-domtokenlist%E2%91%A0%E2%91%A2
+DOMTokenList::DOMTokenList(Element const& associated_element, FlyString associated_attribute)
+    : m_associated_element(associated_element)
+    , m_associated_attribute(move(associated_attribute))
+{
+    auto value = associated_element.get_attribute(m_associated_attribute);
+    associated_attribute_changed(value);
+}
+
+// https://dom.spec.whatwg.org/#ref-for-domtokenlist%E2%91%A0%E2%91%A1
+void DOMTokenList::associated_attribute_changed(StringView value)
+{
+    m_token_set.clear();
+
+    if (value.is_empty())
+        return;
+
+    auto split_values = value.split_view(' ');
+    for (auto const& split_value : split_values)
+        append_to_ordered_set(m_token_set, split_value);
+}
+
+// https://dom.spec.whatwg.org/#ref-for-dfn-supported-property-indices%E2%91%A3
+bool DOMTokenList::is_supported_property_index(u32 index) const
+{
+    return index < m_token_set.size();
+}
+
+// https://dom.spec.whatwg.org/#dom-domtokenlist-item
+String const& DOMTokenList::item(size_t index) const
+{
+    static const String null_string {};
+
+    // 1. If index is equal to or greater than this’s token set’s size, then return null.
+    if (index >= m_token_set.size())
+        return null_string;
+
+    // 2. Return this’s token set[index].
+    return m_token_set[index];
+}
+
+// https://dom.spec.whatwg.org/#dom-domtokenlist-contains
+bool DOMTokenList::contains(StringView token)
+{
+    return m_token_set.contains_slow(token);
+}
+
+// https://dom.spec.whatwg.org/#dom-domtokenlist-add
+ExceptionOr<void> DOMTokenList::add(Vector<String> const& tokens)
+{
+    // 1. For each token in tokens:
+    for (auto const& token : tokens) {
+        // a. If token is the empty string, then throw a "SyntaxError" DOMException.
+        // b. If token contains any ASCII whitespace, then throw an "InvalidCharacterError" DOMException.
+        if (auto exception = validate_token(token); exception.is_exception())
+            return exception;
+
+        // 2. For each token in tokens, append token to this’s token set.
+        append_to_ordered_set(m_token_set, token);
+    }
+
+    // 3. Run the update steps.
+    run_update_steps();
+    return {};
+}
+
+// https://dom.spec.whatwg.org/#dom-domtokenlist-remove
+ExceptionOr<void> DOMTokenList::remove(Vector<String> const& tokens)
+{
+    // 1. For each token in tokens:
+    for (auto const& token : tokens) {
+        // a. If token is the empty string, then throw a "SyntaxError" DOMException.
+        // b. If token contains any ASCII whitespace, then throw an "InvalidCharacterError" DOMException.
+        if (auto exception = validate_token(token); exception.is_exception())
+            return exception;
+
+        // 2. For each token in tokens, remove token from this’s token set.
+        remove_from_ordered_set(m_token_set, token);
+    }
+
+    // 3. Run the update steps.
+    run_update_steps();
+    return {};
+}
+
+// https://dom.spec.whatwg.org/#dom-domtokenlist-toggle
+ExceptionOr<bool> DOMTokenList::toggle(String const& token, Optional<bool> force)
+{
+    // 1. If token is the empty string, then throw a "SyntaxError" DOMException.
+    // 2. If token contains any ASCII whitespace, then throw an "InvalidCharacterError" DOMException.
+    if (auto exception = validate_token(token); exception.is_exception())
+        return exception.exception();
+
+    // 3. If this’s token set[token] exists, then:
+    if (contains(token)) {
+        // a. If force is either not given or is false, then remove token from this’s token set, run the update steps and return false.
+        if (!force.has_value() || !force.value()) {
+            remove_from_ordered_set(m_token_set, token);
+            run_update_steps();
+            return false;
+        }
+
+        // b. Return true.
+        return true;
+    }
+
+    // 4. Otherwise, if force not given or is true, append token to this’s token set, run the update steps, and return true.
+    if (!force.has_value() || force.value()) {
+        append_to_ordered_set(m_token_set, token);
+        run_update_steps();
+        return true;
+    }
+
+    // 5. Return false.
+    return false;
+}
+
+// https://dom.spec.whatwg.org/#dom-domtokenlist-replace
+ExceptionOr<bool> DOMTokenList::replace(String const& token, String const& new_token)
+{
+    // 1. If either token or newToken is the empty string, then throw a "SyntaxError" DOMException.
+    // 2. If either token or newToken contains any ASCII whitespace, then throw an "InvalidCharacterError" DOMException.
+    if (auto exception = validate_token(token); exception.is_exception())
+        return exception.exception();
+    if (auto exception = validate_token(new_token); exception.is_exception())
+        return exception.exception();
+
+    // 3. If this’s token set does not contain token, then return false.
+    if (!contains(token))
+        return false;
+
+    // 4. Replace token in this’s token set with newToken.
+    replace_in_ordered_set(m_token_set, token, new_token);
+
+    // 5. Run the update steps.
+    run_update_steps();
+
+    // 6. Return true.
+    return true;
+}
+
+// https://dom.spec.whatwg.org/#dom-domtokenlist-supports
+// https://dom.spec.whatwg.org/#concept-domtokenlist-validation
+ExceptionOr<bool> DOMTokenList::supports([[maybe_unused]] StringView token)
+{
+    // FIXME: Implement this fully when any use case defines supported tokens.
+
+    // 1. If the associated attribute’s local name does not define supported tokens, throw a TypeError.
+    return DOM::SimpleException {
+        DOM::SimpleExceptionType::TypeError,
+        String::formatted("Attribute {} does not define any supported tokens", m_associated_attribute)
+    };
+
+    // 2. Let lowercase token be a copy of token, in ASCII lowercase.
+    // 3. If lowercase token is present in supported tokens, return true.
+    // 4. Return false.
+}
+
+// https://dom.spec.whatwg.org/#dom-domtokenlist-value
+String DOMTokenList::value() const
+{
+    StringBuilder builder;
+    builder.join(' ', m_token_set);
+    return builder.build();
+}
+
+// https://dom.spec.whatwg.org/#ref-for-concept-element-attributes-set-value%E2%91%A2
+void DOMTokenList::set_value(String value)
+{
+    auto associated_element = m_associated_element.strong_ref();
+    if (!associated_element)
+        return;
+
+    associated_element->set_attribute(m_associated_attribute, move(value));
+}
+
+ExceptionOr<void> DOMTokenList::validate_token(StringView token) const
+{
+    if (token.is_empty())
+        return SyntaxError::create("Non-empty DOM tokens are not allowed");
+    if (any_of(token, is_ascii_space))
+        return InvalidCharacterError::create("DOM tokens containing ASCII whitespace are not allowed");
+    return {};
+}
+
+// https://dom.spec.whatwg.org/#concept-dtl-update
+void DOMTokenList::run_update_steps()
+{
+    auto associated_element = m_associated_element.strong_ref();
+    if (!associated_element)
+        return;
+
+    // 1. If the associated element does not have an associated attribute and token set is empty, then return.
+    if (!associated_element->has_attribute(m_associated_attribute) && m_token_set.is_empty())
+        return;
+
+    // 2. Set an attribute value for the associated element using associated attribute’s local name and the result of running the ordered set serializer for token set.
+    associated_element->set_attribute(m_associated_attribute, value());
+}
+
+}