708f49d906
This represents each element's set of CSS counters. https://drafts.csswg.org/css-lists-3/#css-counters-set Counters are resolved while building the tree. Most elements will not have any counters to keep track of, so as an optimization, we don't create a CountersSet object until the element actually needs one. In order to properly support counters on pseudo-elements, the CountersSet needs to go somewhere else. However, my experiments with placing it on the Layout::Node kept hitting a wall. For now, this is fairly simple at least.
103 lines
4 KiB
C++
103 lines
4 KiB
C++
/*
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* Copyright (c) 2024, Sam Atkins <sam@ladybird.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include "CountersSet.h"
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#include <LibWeb/DOM/Element.h>
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#include <LibWeb/DOM/Node.h>
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namespace Web::CSS {
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// https://drafts.csswg.org/css-lists-3/#instantiate-counter
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Counter& CountersSet::instantiate_a_counter(FlyString name, i32 originating_element_id, bool reversed, Optional<CounterValue> value)
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{
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// 1. Let counters be element’s CSS counters set.
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auto* element = DOM::Node::from_unique_id(originating_element_id);
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// 2. Let innermost counter be the last counter in counters with the name name.
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// If innermost counter’s originating element is element or a previous sibling of element,
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// remove innermost counter from counters.
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auto innermost_counter = last_counter_with_name(name);
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if (innermost_counter.has_value()) {
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auto* originating_node = DOM::Node::from_unique_id(innermost_counter->originating_element_id);
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VERIFY(originating_node);
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auto& innermost_element = verify_cast<DOM::Element>(*originating_node);
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if (&innermost_element == element
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|| (innermost_element.parent() == element->parent() && innermost_element.is_before(*element))) {
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m_counters.remove_first_matching([&innermost_counter](auto& it) {
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return it.name == innermost_counter->name
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&& it.originating_element_id == innermost_counter->originating_element_id;
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});
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}
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}
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// 3. Append a new counter to counters with name name, originating element element,
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// reversed being reversed, and initial value value (if given)
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m_counters.append({
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.name = move(name),
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.originating_element_id = originating_element_id,
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.reversed = reversed,
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.value = value,
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});
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return m_counters.last();
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}
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// https://drafts.csswg.org/css-lists-3/#propdef-counter-set
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void CountersSet::set_a_counter(FlyString name, i32 originating_element_id, CounterValue value)
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{
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if (auto existing_counter = last_counter_with_name(name); existing_counter.has_value()) {
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existing_counter->value = value;
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return;
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}
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// If there is not currently a counter of the given name on the element, the element instantiates
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// a new counter of the given name with a starting value of 0 before setting or incrementing its value.
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// https://drafts.csswg.org/css-lists-3/#valdef-counter-set-counter-name-integer
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auto& counter = instantiate_a_counter(name, originating_element_id, false, 0);
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counter.value = value;
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}
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// https://drafts.csswg.org/css-lists-3/#propdef-counter-increment
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void CountersSet::increment_a_counter(FlyString name, i32 originating_element_id, CounterValue amount)
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{
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if (auto existing_counter = last_counter_with_name(name); existing_counter.has_value()) {
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// FIXME: How should we handle existing counters with no value? Can that happen?
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VERIFY(existing_counter->value.has_value());
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existing_counter->value->saturating_add(amount.value());
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return;
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}
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// If there is not currently a counter of the given name on the element, the element instantiates
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// a new counter of the given name with a starting value of 0 before setting or incrementing its value.
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// https://drafts.csswg.org/css-lists-3/#valdef-counter-set-counter-name-integer
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auto& counter = instantiate_a_counter(name, originating_element_id, false, 0);
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counter.value->saturating_add(amount.value());
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}
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Optional<Counter&> CountersSet::last_counter_with_name(FlyString const& name)
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{
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for (auto& counter : m_counters.in_reverse()) {
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if (counter.name == name)
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return counter;
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}
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return {};
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}
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Optional<Counter&> CountersSet::counter_with_same_name_and_creator(FlyString const& name, i32 originating_element_id)
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{
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return m_counters.first_matching([&](auto& it) {
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return it.name == name && it.originating_element_id == originating_element_id;
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});
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}
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void CountersSet::append_copy(Counter const& counter)
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{
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m_counters.append(counter);
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}
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}
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