ladybird/Userland/Libraries/LibWeb/Encoding/TextEncoder.cpp
Shannon Booth 04c094343f LibWeb+Meta: Add wrapper for the BufferSource/ArrayBufferView IDL types
These wrappers will make it much easier to do various operations on the
different ArrayBuffer-related classes in LibWeb compared to the current
solution, which is to just accept a Handle<Object> everywhere (and use
"any" in the *.idl files).

Co-Authored-By: Matthew Olsson <mattco@serenityos.org>
2023-11-24 08:43:35 +01:00

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/*
* Copyright (c) 2021-2022, Linus Groh <linusg@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibJS/Runtime/TypedArray.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/Encoding/TextEncoder.h>
#include <LibWeb/WebIDL/ExceptionOr.h>
namespace Web::Encoding {
JS_DEFINE_ALLOCATOR(TextEncoder);
WebIDL::ExceptionOr<JS::NonnullGCPtr<TextEncoder>> TextEncoder::construct_impl(JS::Realm& realm)
{
return realm.heap().allocate<TextEncoder>(realm, realm);
}
TextEncoder::TextEncoder(JS::Realm& realm)
: PlatformObject(realm)
{
}
TextEncoder::~TextEncoder() = default;
void TextEncoder::initialize(JS::Realm& realm)
{
Base::initialize(realm);
set_prototype(&Bindings::ensure_web_prototype<Bindings::TextEncoderPrototype>(realm, "TextEncoder"));
}
// https://encoding.spec.whatwg.org/#dom-textencoder-encode
JS::NonnullGCPtr<JS::Uint8Array> TextEncoder::encode(String const& input) const
{
// NOTE: The AK::String is always UTF-8, so most of these steps are no-ops.
// 1. Convert input to an I/O queue of scalar values.
// 2. Let output be the I/O queue of bytes « end-of-queue ».
// 3. While true:
// 1. Let item be the result of reading from input.
// 2. Let result be the result of processing an item with item, an instance of the UTF-8 encoder, input, output, and "fatal".
// 3. Assert: result is not an error.
// 4. If result is finished, then convert output into a byte sequence and return a Uint8Array object wrapping an ArrayBuffer containing output.
auto byte_buffer = MUST(ByteBuffer::copy(input.bytes()));
auto array_length = byte_buffer.size();
auto array_buffer = JS::ArrayBuffer::create(realm(), move(byte_buffer));
return JS::Uint8Array::create(realm(), array_length, *array_buffer);
}
// https://encoding.spec.whatwg.org/#dom-textencoder-encodeinto
TextEncoderEncodeIntoResult TextEncoder::encode_into(String const& source, JS::Handle<WebIDL::BufferSource> const& destination) const
{
auto& data = destination->viewed_array_buffer()->buffer();
// 1. Let read be 0.
unsigned long long read = 0;
// 2. Let written be 0.
unsigned long long written = 0;
// NOTE: The AK::String is always UTF-8, so most of these steps are no-ops.
// 3. Let encoder be an instance of the UTF-8 encoder.
// 4. Let unused be the I/O queue of scalar values « end-of-queue ».
// 5. Convert source to an I/O queue of scalar values.
auto code_points = source.code_points();
auto it = code_points.begin();
// 6. While true:
while (true) {
// 6.1. Let item be the result of reading from source.
// 6.2. Let result be the result of running encoders handler on unused and item.
// 6.3. If result is finished, then break.
if (it.done())
break;
auto item = *it;
auto result = it.underlying_code_point_bytes();
// 6.4. Otherwise:
// 6.4.1. If destinations byte length written is greater than or equal to the number of bytes in result, then:
if (data.size() - written >= result.size()) {
// 6.4.1.1. If item is greater than U+FFFF, then increment read by 2.
if (item > 0xffff) {
read += 2;
}
// 6.4.1.2. Otherwise, increment read by 1.
else {
read++;
}
// 6.4.1.3. Write the bytes in result into destination, with startingOffset set to written.
// 6.4.1.4. Increment written by the number of bytes in result.
for (auto byte : result)
data[written++] = byte;
}
// 6.4.2. Otherwise, break.
else {
break;
}
++it;
}
// 7. Return «[ "read" → read, "written" → written ]».
return { read, written };
}
// https://encoding.spec.whatwg.org/#dom-textencoder-encoding
FlyString const& TextEncoder::encoding()
{
static FlyString const encoding = "utf-8"_fly_string;
return encoding;
}
}