ladybird/Libraries/LibWeb/CSS/CountersSet.cpp

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/*
* Copyright (c) 2024, Sam Atkins <sam@ladybird.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "CountersSet.h"
#include <LibWeb/DOM/Element.h>
#include <LibWeb/DOM/Node.h>
namespace Web::CSS {
// https://drafts.csswg.org/css-lists-3/#instantiate-counter
Counter& CountersSet::instantiate_a_counter(FlyString name, UniqueNodeID originating_element_id, bool reversed, Optional<CounterValue> value)
{
// 1. Let counters be elements CSS counters set.
auto* element = DOM::Node::from_unique_id(originating_element_id);
// 2. Let innermost counter be the last counter in counters with the name name.
// If innermost counters originating element is element or a previous sibling of element,
// remove innermost counter from counters.
auto innermost_counter = last_counter_with_name(name);
if (innermost_counter.has_value()) {
auto* originating_node = DOM::Node::from_unique_id(innermost_counter->originating_element_id);
VERIFY(originating_node);
auto& innermost_element = verify_cast<DOM::Element>(*originating_node);
if (&innermost_element == element
|| (innermost_element.parent() == element->parent() && innermost_element.is_before(*element))) {
m_counters.remove_first_matching([&innermost_counter](auto& it) {
return it.name == innermost_counter->name
&& it.originating_element_id == innermost_counter->originating_element_id;
});
}
}
// 3. Append a new counter to counters with name name, originating element element,
// reversed being reversed, and initial value value (if given)
m_counters.append({
.name = move(name),
.originating_element_id = originating_element_id,
.reversed = reversed,
.value = value,
});
return m_counters.last();
}
// https://drafts.csswg.org/css-lists-3/#propdef-counter-set
void CountersSet::set_a_counter(FlyString name, UniqueNodeID originating_element_id, CounterValue value)
{
if (auto existing_counter = last_counter_with_name(name); existing_counter.has_value()) {
existing_counter->value = value;
return;
}
// If there is not currently a counter of the given name on the element, the element instantiates
// a new counter of the given name with a starting value of 0 before setting or incrementing its value.
// https://drafts.csswg.org/css-lists-3/#valdef-counter-set-counter-name-integer
auto& counter = instantiate_a_counter(name, originating_element_id, false, 0);
counter.value = value;
}
// https://drafts.csswg.org/css-lists-3/#propdef-counter-increment
void CountersSet::increment_a_counter(FlyString name, UniqueNodeID originating_element_id, CounterValue amount)
{
if (auto existing_counter = last_counter_with_name(name); existing_counter.has_value()) {
// FIXME: How should we handle existing counters with no value? Can that happen?
VERIFY(existing_counter->value.has_value());
existing_counter->value->saturating_add(amount.value());
return;
}
// If there is not currently a counter of the given name on the element, the element instantiates
// a new counter of the given name with a starting value of 0 before setting or incrementing its value.
// https://drafts.csswg.org/css-lists-3/#valdef-counter-set-counter-name-integer
auto& counter = instantiate_a_counter(name, originating_element_id, false, 0);
counter.value->saturating_add(amount.value());
}
Optional<Counter&> CountersSet::last_counter_with_name(FlyString const& name)
{
for (auto& counter : m_counters.in_reverse()) {
if (counter.name == name)
return counter;
}
return {};
}
Optional<Counter&> CountersSet::counter_with_same_name_and_creator(FlyString const& name, UniqueNodeID originating_element_id)
{
return m_counters.first_matching([&](auto& it) {
return it.name == name && it.originating_element_id == originating_element_id;
});
}
void CountersSet::append_copy(Counter const& counter)
{
m_counters.append(counter);
}
}