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// Copyright 2018 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.
#include <cstdint>
#include <string>
#include "absl/strings/string_view.h"
#include "quiche/quic/core/qpack/qpack_instructions.h"
#include "quiche/quic/platform/api/quic_export.h"
namespace quic {
// Generic instruction encoder class. Takes a QpackLanguage that describes a
// language, that is, a set of instruction opcodes together with a list of
// fields that follow each instruction.
class QUIC_EXPORT_PRIVATE QpackInstructionEncoder {
QpackInstructionEncoder(const QpackInstructionEncoder&) = delete;
QpackInstructionEncoder& operator=(const QpackInstructionEncoder&) = delete;
// Append encoded instruction to |output|.
void Encode(const QpackInstructionWithValues& instruction_with_values,
std::string* output);
enum class State {
// Write instruction opcode to |byte_|.
// Select state based on type of current field.
// Write static bit to |byte_|.
// Encode an integer (|varint_| or |varint2_| or string length) with a
// prefix, using |byte_| for the high bits.
// Determine if Huffman encoding should be used for the header name or
// value, set |use_huffman_| and |string_length_| appropriately, write the
// Huffman bit to |byte_|.
// Write header name or value, performing Huffman encoding if |use_huffman_|
// is true.
// One method for each state. Some append encoded bytes to |output|.
// Some only change internal state.
void DoOpcode();
void DoStartField();
void DoSBit(bool s_bit);
void DoVarintEncode(uint64_t varint, uint64_t varint2, std::string* output);
void DoStartString(absl::string_view name, absl::string_view value);
void DoWriteString(absl::string_view name, absl::string_view value,
std::string* output);
// True if name or value should be Huffman encoded.
bool use_huffman_;
// Length of name or value string to be written.
// If |use_huffman_| is true, length is after Huffman encoding.
size_t string_length_;
// Storage for a single byte that contains multiple fields, that is, multiple
// states are writing it.
uint8_t byte_;
// Encoding state.
State state_;
// Instruction currently being decoded.
const QpackInstruction* instruction_;
// Field currently being decoded.
QpackInstructionFields::const_iterator field_;
} // namespace quic