78 lines
1.9 KiB
C++
78 lines
1.9 KiB
C++
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/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include "CallbackOStream.h"
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#include <algorithm>
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#include <cassert>
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namespace facebook {
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namespace hermes {
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namespace inspector {
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namespace detail {
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CallbackOStream::CallbackOStream(size_t sz, Fn cb)
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: std::ostream(&sbuf_), sbuf_(sz, std::move(cb)) {}
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CallbackOStream::StreamBuf::StreamBuf(size_t sz, Fn cb)
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: sz_(sz), buf_(std::make_unique<char[]>(sz)), cb_(std::move(cb)) {
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reset();
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}
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CallbackOStream::StreamBuf::~StreamBuf() {
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sync();
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}
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std::streambuf::int_type CallbackOStream::StreamBuf::overflow(
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std::streambuf::int_type ch) {
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assert(pptr() <= epptr() && "overflow expects the buffer not to be overfull");
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if (!pptr()) {
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return traits_type::eof();
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}
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*pptr() = ch;
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pbump(1);
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if (sync() == 0) {
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return traits_type::not_eof(ch);
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}
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// Set to nullptr on failure.
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setp(nullptr, nullptr);
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return traits_type::eof();
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}
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int CallbackOStream::StreamBuf::sync() {
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try {
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return pbase() == pptr() || cb_(take()) ? 0 : -1;
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} catch (...) {
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return -1;
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}
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}
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void CallbackOStream::StreamBuf::reset() {
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assert(sz_ > 0 && "Buffer cannot be empty.");
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// std::streambuf::overflow accepts the character that caused the overflow as
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// a parameter. Part of handling the overflow is adding this character to the
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// stream. We choose to do this by stealing a byte at the end of the "put"
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// area where the character can be written, even if the area is otherwise
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// full, immediately prior to being flushed.
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setp(&buf_[0], &buf_[0] + sz_ - 1);
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}
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std::string CallbackOStream::StreamBuf::take() {
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const size_t strsz = pptr() - pbase();
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reset();
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return std::string(pbase(), strsz);
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}
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} // namespace detail
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} // namespace inspector
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} // namespace hermes
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} // namespace facebook
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