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666251caf7
Added evaluating supports() conditions in the import preload scanner and not emitting URLs if they do not match. There is no use preloading imports for features we do not support, as they will never be loaded since supports() conditions cannot change mid-page. Also tweaked internals a bit (added a generic ResetState internal func) and added a new gtest for import supports(), plus a WPT test print test. Differential Revision: https://phabricator.services.mozilla.com/D175432
95 lines
3.2 KiB
C++
95 lines
3.2 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=2 sw=2 et tw=78: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_ImportScanner_h
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#define mozilla_ImportScanner_h
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/* A simple best-effort scanner for @import rules for the HTML parser */
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#include "nsString.h"
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#include "nsTArray.h"
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namespace mozilla {
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struct ImportScanner final {
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ImportScanner() = default;
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// Called when a <style> element starts.
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//
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// Note that this function cannot make assumptions about the internal state,
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// as you can nest <svg:style> elements.
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void Start();
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// Called when a <style> element ends. Returns the list of URLs scanned.
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nsTArray<nsString> Stop();
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// Whether Scan() should be called.
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bool ShouldScan() const {
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return mState != State::OutsideOfStyleElement && mState != State::Done;
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}
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// Scan() should be called when text content is parsed, and returns an array
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// of found URLs, if any.
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//
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// Asserts ShouldScan() returns true.
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nsTArray<nsString> Scan(Span<const char16_t> aFragment);
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private:
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enum class State {
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// Initial state, doesn't scan anything until Start() is called.
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OutsideOfStyleElement,
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// In an idle state during the stylesheet scanning, either at the
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// beginning or after parsing a rule.
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Idle,
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// We've seen a '/' character, but not the '*' yet, so we don't know if
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// it's a comment.
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MaybeAtCommentStart,
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// We're inside a comment.
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AtComment,
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// We've seen a '*' while we're in a comment, but we don't now yet whether
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// '/' comes afterwards (thus ending the comment).
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MaybeAtCommentEnd,
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// We're parsing the '@' rule name.
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AtRuleName,
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// We're parsing the '@' rule value.
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AtRuleValue,
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// We're parsing the '@' rule value and we've seen the delimiter (quote or
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// url() function) that encloses the url.
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AtRuleValueDelimited,
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// We've seen the url, but haven't seen the ';' finishing the rule yet.
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AfterRuleValue,
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// We've seen anything that is not an @import or a @charset rule, and thus
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// further @import / @charset should not be parsed.
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Done,
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};
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void ResetState();
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void EmitUrl();
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[[nodiscard]] State Scan(char16_t aChar);
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static constexpr const uint32_t kMaxRuleNameLength = 7; // (charset, import)
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State mState = State::OutsideOfStyleElement;
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nsAutoStringN<kMaxRuleNameLength> mRuleName;
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nsAutoStringN<128> mRuleValue;
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nsAutoStringN<128> mAfterRuleValue;
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nsTArray<nsString> mUrlsFound;
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// This is conceptually part of the AtRuleValue* / AfterRuleValue states,
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// and serves to differentiate between @import (where we actually care about
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// the value) and @charset (where we don't). It's just more convenient this
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// way than having separate states for them.
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bool mInImportRule = false;
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// If we're in the AtRuleValueDelimited state, what is the closing character
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// that will end the value. This is either a parenthesis (for unquoted
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// urls), or a quote, either single or double.
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char16_t mUrlValueDelimiterClosingChar = 0;
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};
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} // namespace mozilla
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#endif
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