Source/WebCore/dom/SpeculationRulesMatcher.cpp

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#include "config.h"
#include "SpeculationRulesMatcher.h"

#include "CheckVisibilityOptions.h"
#include "Document.h"
#include "Element.h"
#include "HTMLAnchorElement.h"
#include "JSDOMGlobalObject.h"
#include "ReferrerPolicy.h"
#include "ScriptController.h"
#include "SelectorQuery.h"
#include "ShadowRoot.h"
#include "SpeculationRules.h"
#include "URLPattern.h"
#include "URLPatternOptions.h"

namespace WebCore {

static bool isUnslottedElement(Element& element)
{
    for (RefPtr ancestor = &element; ancestor; ) {
        RefPtr parent = ancestor->parentElement();
        if (parent && parent->shadowRoot() && !ancestor->assignedSlot())
            return true;
        ancestor = WTF::move(parent);
    }
    return false;
}

static bool matches(const SpeculationRules::DocumentPredicate&, Document&, HTMLAnchorElement&);

static bool matches(const SpeculationRules::URLPatternPredicate& predicate, HTMLAnchorElement& anchor)
{
    for (const auto& patternString : predicate.patterns) {
        ExceptionOr<Ref<URLPattern>> exceptionOrPattern = URLPattern::create(anchor.protectedDocument(), patternString, String(anchor.document().baseURL().string()), URLPatternOptions());
        if (exceptionOrPattern.hasException())
            continue;

        Ref<URLPattern> pattern = exceptionOrPattern.returnValue();
        auto result = pattern->test(anchor.protectedDocument(), anchor.href().string(), String(anchor.document().baseURL().string()));
        if (!result.hasException() && result.returnValue())
            return true;
    }
    return false;
}

static bool matches(const SpeculationRules::CSSSelectorPredicate& predicate, Element& element)
{
    for (const auto& selectorString : predicate.selectors) {
        auto query = element.protectedDocument()->selectorQueryForString(selectorString);
        if (query.hasException())
            continue;
        if (query.returnValue().matches(element))
            return true;
    }
    return false;
}

static bool matches(const Box<SpeculationRules::Conjunction>& predicate, Document& document, HTMLAnchorElement& anchor)
{
    for (const auto& clause : predicate->clauses) {
        if (!matches(clause, document, anchor))
            return false;
    }
    return true;
}

static bool matches(const Box<SpeculationRules::Disjunction>& predicate, Document& document, HTMLAnchorElement& anchor)
{
    if (predicate->clauses.isEmpty())
        return false;

    for (const auto& clause : predicate->clauses) {
        if (matches(clause, document, anchor))
            return true;
    }
    return false;
}

static bool matches(const Box<SpeculationRules::Negation>& predicate, Document& document, HTMLAnchorElement& anchor)
{
    return !matches(*predicate->clause, document, anchor);
}

// https://html.spec.whatwg.org/C#dr-predicate-matches
static bool matches(const SpeculationRules::DocumentPredicate& predicate, Document& document, HTMLAnchorElement& anchor)
{
    return WTF::switchOn(predicate.value(),
        [&] (const SpeculationRules::URLPatternPredicate& p) { return matches(p, anchor); },
        [&] (const SpeculationRules::CSSSelectorPredicate& p) { return matches(p, anchor); },
        [&] (const Box<SpeculationRules::Conjunction>& p) { return matches(p, document, anchor); },
        [&] (const Box<SpeculationRules::Disjunction>& p) { return matches(p, document, anchor); },
        [&] (const Box<SpeculationRules::Negation>& p) { return matches(p, document, anchor); }
    );
}

// https://html.spec.whatwg.org/C#find-matching-links
std::optional<PrefetchRule> SpeculationRulesMatcher::hasMatchingRule(Document& document, HTMLAnchorElement& anchor)
{
    Ref speculationRules = document.speculationRules();
    if (speculationRules->prefetchRules().isEmptyIgnoringNullReferences())
        return std::nullopt;

    // 2.2 If descendant is not being rendered or is part of skipped contents, then continue.
    // An element is not being rendered if:
    // - It's unslotted (light DOM child of a shadow host without a slot assignment)
    // - It or an ancestor has display:none
    // - It's part of content-visibility:hidden content
    if (isUnslottedElement(anchor) || !anchor.checkVisibility(CheckVisibilityOptions { }))
        return std::nullopt;

    const auto& url = anchor.href();

    for (auto [node, rules] : speculationRules->prefetchRules()) {
        for (const auto& rule : rules) {
            for (const auto& href : rule.urls) {
                if (href == url)
                    return PrefetchRule { rule.tags, rule.referrerPolicy, rule.eagerness };
            }

            if (rule.predicate && matches(rule.predicate.value(), document, anchor)) {
                // For document rules, if the rule doesn't specify a referrer policy,
                // use the link element's referrerPolicy attribute if present.
                auto referrerPolicy = rule.referrerPolicy;
                if (!referrerPolicy) {
                    auto linkReferrerPolicy = anchor.referrerPolicy();
                    if (linkReferrerPolicy != ReferrerPolicy::EmptyString)
                        referrerPolicy = linkReferrerPolicy;
                }
                return PrefetchRule { rule.tags, referrerPolicy, rule.eagerness };
            }
        }
    }

    return std::nullopt;
}

} // namespace WebCore