Source/WebCore/dom/TextEncoderStreamEncoder.cpp

/*
 * Copyright (C) 2020 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "TextEncoderStreamEncoder.h"

#include <JavaScriptCore/GenericTypedArrayViewInlines.h>
#include <JavaScriptCore/JSCInlines.h>
#include <JavaScriptCore/JSGenericTypedArrayViewInlines.h>
#include <wtf/unicode/CharacterNames.h>

namespace WebCore {

RefPtr<Uint8Array> TextEncoderStreamEncoder::encode(const String& input)
{
    StringView view(input);

    if (!view.length())
        return nullptr;

    Vector<uint8_t> bytes(WTF::checkedProduct<size_t>(view.length() + 1, 3));
    auto bytesSpan = bytes.mutableSpan();
    size_t bytesWritten = 0;

    for (size_t cptr = 0; cptr < view.length(); cptr++) {
        // https://encoding.spec.whatwg.org/#convert-code-unit-to-scalar-value
        auto token = view[cptr];
        if (m_pendingLeadSurrogate) {
            auto leadSurrogate = *std::exchange(m_pendingLeadSurrogate, std::nullopt);
            if (U16_IS_TRAIL(token)) {
                auto codePoint = U16_GET_SUPPLEMENTARY(leadSurrogate, token);
                U8_APPEND_UNSAFE(bytesSpan, bytesWritten, codePoint);
                continue;
            }
            U8_APPEND_UNSAFE(bytesSpan, bytesWritten, replacementCharacter);
        }
        if (U16_IS_LEAD(token)) {
            m_pendingLeadSurrogate = token;
            continue;
        }
        if (U16_IS_TRAIL(token)) {
            U8_APPEND_UNSAFE(bytesSpan, bytesWritten, replacementCharacter);
            continue;
        }
        U8_APPEND_UNSAFE(bytesSpan, bytesWritten, token);
    }

    if (!bytesWritten)
        return nullptr;

    return Uint8Array::tryCreate(bytes.span().first(bytesWritten));
}

RefPtr<Uint8Array> TextEncoderStreamEncoder::flush()
{
    if (!m_pendingLeadSurrogate)
        return nullptr;

    constexpr std::array<uint8_t, 3> byteSequence { 0xEF, 0xBF, 0xBD };
    return Uint8Array::tryCreate(byteSequence);
}

}