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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 NET_SPDY_HPACK_ENCODER_H_
#define NET_SPDY_HPACK_ENCODER_H_
#include <map>
#include <string>
#include <vector>
#include "base/basictypes.h"
#include "base/macros.h"
#include "base/strings/string_piece.h"
#include "net/base/net_export.h"
#include "net/spdy/hpack_header_table.h"
#include "net/spdy/hpack_output_stream.h"
// An HpackEncoder encodes header sets as outlined in
// http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-06
namespace net {
class HpackHuffmanTable;
namespace test {
class HpackEncoderPeer;
} // namespace test
class NET_EXPORT_PRIVATE HpackEncoder {
public:
friend class test::HpackEncoderPeer;
// |table| is an initialized HPACK Huffman table, having an
// externally-managed lifetime which spans beyond HpackEncoder.
explicit HpackEncoder(const HpackHuffmanTable& table);
~HpackEncoder();
// Encodes the given header set into the given string. Returns
// whether or not the encoding was successful.
bool EncodeHeaderSet(const std::map<std::string, std::string>& header_set,
std::string* output);
// Encodes the given header set into the given string. Only non-indexed
// literal representations are emitted, bypassing the header table. Huffman
// coding is also not used. Returns whether the encoding was successful.
// TODO(jgraettinger): Enable Huffman coding once the table as stablized.
bool EncodeHeaderSetWithoutCompression(
const std::map<std::string, std::string>& header_set,
std::string* output);
// Called upon a change to SETTINGS_HEADER_TABLE_SIZE. Specifically, this
// is to be called after receiving (and sending an acknowledgement for) a
// SETTINGS_HEADER_TABLE_SIZE update from the remote decoding endpoint.
void ApplyHeaderTableSizeSetting(size_t size_setting) {
header_table_.SetSettingsHeaderTableSize(size_setting);
}
private:
typedef std::pair<base::StringPiece, base::StringPiece> Representation;
typedef std::vector<Representation> Representations;
// Emits a static/dynamic indexed representation (Section 4.2).
void EmitDynamicIndex(HpackEntry* entry);
void EmitStaticIndex(HpackEntry* entry);
// Emits a literal representation (Section 4.3).
void EmitIndexedLiteral(const Representation& representation);
void EmitNonIndexedLiteral(const Representation& representation);
void EmitLiteral(const Representation& representation);
// Emits a Huffman or identity string (whichever is smaller).
void EmitString(base::StringPiece str);
// Determines the representation delta required to encode |header_set| in
// the current header table context. Entries in the reference set are
// enumerated and marked with membership in the current |header_set|.
// Representations which must be explicitly emitted are returned.
Representations DetermineEncodingDelta(
const std::map<std::string, std::string>& header_set);
static void CookieToCrumbs(const Representation& cookie,
Representations* crumbs_out);
HpackHeaderTable header_table_;
HpackOutputStream output_stream_;
bool allow_huffman_compression_;
const HpackHuffmanTable& huffman_table_;
DISALLOW_COPY_AND_ASSIGN(HpackEncoder);
};
} // namespace net
#endif // NET_SPDY_HPACK_ENCODER_H_
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