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/*
* Copyright (C) 2010-2018 Apple Inc. All rights reserved.
* Copyright (C) 2012 Google Inc. All rights reserved.
* Copyright (C) 2017 Yusuke Suzuki <utatane.tea@gmail.com>. All rights reserved.
* Copyright (C) 2017 Mozilla Foundation. All rights reserved.
*
* 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 http://mozilla.org/MPL/2.0/.
*/
#pragma once
#include <wtf/text/EscapedFormsForJSON.h>
#include <wtf/text/ParsingUtilities.h>
#include <wtf/text/StringBuilderInternals.h>
#include <wtf/text/WTFString.h>
namespace WTF {
template<typename OutputCharacterType, typename InputCharacterType>
ALWAYS_INLINE static bool appendEscapedJSONStringContent(std::span<OutputCharacterType>& output, std::span<const InputCharacterType> input)
{
for (; !input.empty(); skip(input, 1)) {
auto character = input.front();
if (character <= 0xFF) [[likely]] {
auto escaped = escapedFormsForJSON[character];
if (!escaped) [[likely]] {
consume(output) = character;
continue;
}
output[0] = '\\';
output[1] = escaped;
skip(output, 2);
if (escaped == 'u') [[unlikely]] {
output[0] = '0';
output[1] = '0';
output[2] = upperNibbleToLowercaseASCIIHexDigit(character);
output[3] = lowerNibbleToLowercaseASCIIHexDigit(character);
skip(output, 4);
}
continue;
}
// We can end up calling appendEscapedJSONStringContent if we've already proven the string has only Latin1 characters when stringifying JSONs.
// This optimization prevents us from bailing out mid-stream just because we saw e.g. a UTF-16 substring that was actually Latin1.
if constexpr (std::same_as<OutputCharacterType, Latin1Character>)
return false;
if (!U16_IS_SURROGATE(character)) [[likely]] {
consume(output) = character;
continue;
}
if (input.size() > 1) {
auto next = input[1];
bool isValidSurrogatePair = U16_IS_SURROGATE_LEAD(character) && U16_IS_TRAIL(next);
if (isValidSurrogatePair) {
output[0] = character;
output[1] = next;
skip(output, 2);
skip(input, 1);
continue;
}
}
uint8_t upper = static_cast<uint32_t>(character) >> 8;
uint8_t lower = static_cast<uint8_t>(character);
output[0] = '\\';
output[1] = 'u';
output[2] = upperNibbleToLowercaseASCIIHexDigit(upper);
output[3] = lowerNibbleToLowercaseASCIIHexDigit(upper);
output[4] = upperNibbleToLowercaseASCIIHexDigit(lower);
output[5] = lowerNibbleToLowercaseASCIIHexDigit(lower);
skip(output, 6);
}
return true;
}
} // namespace WTF
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