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// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_BINDINGS_BIGINT_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_BINDINGS_BIGINT_H_
#include <optional>
#include "base/compiler_specific.h"
#include "third_party/abseil-cpp/absl/numeric/int128.h"
#include "third_party/blink/renderer/platform/platform_export.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"
#include "v8/include/v8-context.h"
#include "v8/include/v8-forward.h"
#include "v8/include/v8-local-handle.h"
#include "v8/include/v8-primitive.h"
#include "v8/include/v8-value.h"
namespace blink {
class ExceptionState;
class PLATFORM_EXPORT BigInt final {
public:
BigInt() = default;
explicit BigInt(v8::Local<v8::BigInt> bigint) {
int word_count = bigint->WordCount();
words_.resize(word_count);
bigint->ToWordsArray(&sign_bit_, &word_count, words_.data());
}
bool IsNegative() const { return sign_bit_ != 0; }
bool FitsIn128Bits() const { return words_.size() <= 2; }
v8::Local<v8::BigInt> ToV8(v8::Local<v8::Context> context) const {
return v8::BigInt::NewFromWords(context, sign_bit_, words_.size(),
words_.data())
.ToLocalChecked();
}
// Will return nullopt if this is negative or will not fit in 128 bits.
std::optional<absl::uint128> ToUInt128() const {
if (IsNegative() || !FitsIn128Bits()) {
return std::nullopt;
}
if (words_.size() == 0) {
return 0;
}
if (words_.size() == 1) {
return words_[0];
}
return absl::MakeUint128(words_[1], words_[0]);
}
private:
Vector<uint64_t> words_; // least significant at the front
int sign_bit_ = 0; // 0 for positive/zero, 1 for negative
};
// Convert a value to a BigInt. This can fail depending on the input type
// and value.
// https://webidl.spec.whatwg.org/#es-bigint
PLATFORM_EXPORT BigInt ToBigIntSlow(v8::Isolate*,
v8::Local<v8::Value>,
ExceptionState&);
inline BigInt ToBigInt(v8::Isolate* isolate,
v8::Local<v8::Value> value,
ExceptionState& exception_state) {
// Fast case. The value is already a BigInt.
if (value->IsBigInt()) [[likely]] {
return BigInt(value.As<v8::BigInt>());
}
return ToBigIntSlow(isolate, value, exception_state);
}
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_BINDINGS_BIGINT_H_
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