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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 sw=2 et tw=78: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#ifndef mozilla_ImportScanner_h
#define mozilla_ImportScanner_h
/* A simple best-effort scanner for @import rules for the HTML parser */
#include "nsString.h"
#include "nsTArray.h"
namespace mozilla {
struct ImportScanner final {
ImportScanner() = default;
// Called when a <style> element starts.
// Note that this function cannot make assumptions about the internal state,
// as you can nest <svg:style> elements.
void Start();
// Called when a <style> element ends. Returns the list of URLs scanned.
nsTArray<nsString> Stop();
// Whether Scan() should be called.
bool ShouldScan() const {
return mState != State::OutsideOfStyleElement && mState != State::Done;
// Scan() should be called when text content is parsed, and returns an array
// of found URLs, if any.
// Asserts ShouldScan() returns true.
nsTArray<nsString> Scan(Span<const char16_t> aFragment);
enum class State {
// Initial state, doesn't scan anything until Start() is called.
// In an idle state during the stylesheet scanning, either at the
// beginning or after parsing a rule.
// We've seen a '/' character, but not the '*' yet, so we don't know if
// it's a comment.
// We're inside a comment.
// We've seen a '*' while we're in a comment, but we don't now yet whether
// '/' comes afterwards (thus ending the comment).
// We're parsing the '@' rule name.
// We're parsing the '@' rule value.
// We're parsing the '@' rule value and we've seen the delimiter (quote or
// url() function) that encloses the url.
// We've seen the url, but haven't seen the ';' finishing the rule yet.
// We've seen anything that is not an @import or a @charset rule, and thus
// further @import / @charset should not be parsed.
void ResetState();
void EmitUrl();
[[nodiscard]] State Scan(char16_t aChar);
static constexpr const uint32_t kMaxRuleNameLength = 7; // (charset, import)
State mState = State::OutsideOfStyleElement;
nsAutoStringN<kMaxRuleNameLength> mRuleName;
nsAutoStringN<128> mRuleValue;
nsAutoStringN<128> mAfterRuleValue;
nsTArray<nsString> mUrlsFound;
// This is conceptually part of the AtRuleValue* / AfterRuleValue states,
// and serves to differentiate between @import (where we actually care about
// the value) and @charset (where we don't). It's just more convenient this
// way than having separate states for them.
bool mInImportRule = false;
// If we're in the AtRuleValueDelimited state, what is the closing character
// that will end the value. This is either a parenthesis (for unquoted
// urls), or a quote, either single or double.
char16_t mUrlValueDelimiterClosingChar = 0;
} // namespace mozilla