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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef QUICHE_SPDY_CORE_HPACK_HPACK_OUTPUT_STREAM_H_
#define QUICHE_SPDY_CORE_HPACK_HPACK_OUTPUT_STREAM_H_
#include <cstdint>
#include <map>
#include <string>
#include "absl/strings/string_view.h"
#include "common/platform/api/quiche_export.h"
#include "spdy/core/hpack/hpack_constants.h"
// All section references below are to
// http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-08
namespace spdy {
// An HpackOutputStream handles all the low-level details of encoding
// header fields.
class QUICHE_EXPORT_PRIVATE HpackOutputStream {
public:
HpackOutputStream();
HpackOutputStream(const HpackOutputStream&) = delete;
HpackOutputStream& operator=(const HpackOutputStream&) = delete;
~HpackOutputStream();
// Appends the lower |bit_size| bits of |bits| to the internal buffer.
//
// |bit_size| must be > 0 and <= 8. |bits| must not have any bits
// set other than the lower |bit_size| bits.
void AppendBits(uint8_t bits, size_t bit_size);
// Simply forwards to AppendBits(prefix.bits, prefix.bit-size).
void AppendPrefix(HpackPrefix prefix);
// Directly appends |buffer|.
void AppendBytes(absl::string_view buffer);
// Appends the given integer using the representation described in
// 6.1. If the internal buffer ends on a byte boundary, the prefix
// length N is taken to be 8; otherwise, it is taken to be the
// number of bits to the next byte boundary.
//
// It is guaranteed that the internal buffer will end on a byte
// boundary after this function is called.
void AppendUint32(uint32_t I);
// Return pointer to internal buffer. |bit_offset_| needs to be zero.
std::string* MutableString();
// Swaps the internal buffer with |output|, then resets state.
void TakeString(std::string* output);
// Gives up to |max_size| bytes of the internal buffer to |output|. Resets
// internal state with the overflow.
void BoundedTakeString(size_t max_size, std::string* output);
// Size in bytes of stream's internal buffer.
size_t size() const { return buffer_.size(); }
// Returns the estimate of dynamically allocated memory in bytes.
size_t EstimateMemoryUsage() const;
private:
// The internal bit buffer.
std::string buffer_;
// If 0, the buffer ends on a byte boundary. If non-zero, the buffer
// ends on the nth most significant bit. Guaranteed to be < 8.
size_t bit_offset_;
};
} // namespace spdy
#endif // QUICHE_SPDY_CORE_HPACK_HPACK_OUTPUT_STREAM_H_