Split net/spdy into core and chromium subdirectories.

net/spdy/hpack/hpack_huffman_table.h

-// 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_HPACK_HUFFMAN_TABLE_H_
-#define NET_SPDY_HPACK_HPACK_HUFFMAN_TABLE_H_
-
-#include <stdint.h>
-
-#include <cstddef>
-#include <vector>
-
-#include "net/base/net_export.h"
-#include "net/spdy/hpack/hpack_constants.h"
-#include "net/spdy/platform/api/spdy_string.h"
-#include "net/spdy/platform/api/spdy_string_piece.h"
-
-namespace net {
-
-namespace test {
-class HpackHuffmanTablePeer;
-}  // namespace test
-
-class HpackInputStream;
-class HpackOutputStream;
-
-// HpackHuffmanTable encodes and decodes string literals using a constructed
-// canonical Huffman code. Once initialized, an instance is read only and
-// may be accessed only through its const interface.
-class NET_EXPORT_PRIVATE HpackHuffmanTable {
- public:
-  friend class test::HpackHuffmanTablePeer;
-
-  typedef HpackHuffmanSymbol Symbol;
-
-  // DecodeTables are multilevel indexes on code prefixes. Each table indexes
-  // a portion of the prefix mapped to DecodeEntry, which in turn either
-  // captures a terminal symbol, or points to the next DecodeTable to consult
-  // with successive portions of the prefix.
-  struct NET_EXPORT_PRIVATE DecodeEntry {
-    DecodeEntry();
-    DecodeEntry(uint8_t next_table_index, uint8_t length, uint16_t symbol_id);
-
-    // The next table to consult. If this is a terminal,
-    // |next_table_index| will be self-referential.
-    uint8_t next_table_index;
-    // Bit-length of terminal code, if this is a terminal. Length of the
-    // longest code having this prefix, if non-terminal.
-    uint8_t length;
-    // Set only for terminal entries.
-    uint16_t symbol_id;
-  };
-  struct NET_EXPORT_PRIVATE DecodeTable {
-    // Number of bits indexed by the chain leading to this table.
-    uint8_t prefix_length;
-    // Number of additional prefix bits this table indexes.
-    uint8_t indexed_length;
-    // Entries are represented as a length |size()| slice into
-    // |decode_entries_| beginning at |entries_offset|.
-    size_t entries_offset;
-    // Returns |1 << indexed_length|.
-    size_t size() const;
-  };
-
-  HpackHuffmanTable();
-  ~HpackHuffmanTable();
-
-  // Prepares HpackHuffmanTable to encode & decode the canonical Huffman
-  // code as determined by the given symbols. Must be called exactly once.
-  // Returns false if the input symbols define an invalid coding, and true
-  // otherwise. Symbols must be presented in ascending ID order with no gaps,
-  // and |symbol_count| must fit in a uint16_t.
-  bool Initialize(const Symbol* input_symbols, size_t symbol_count);
-
-  // Returns whether Initialize() has been successfully called.
-  bool IsInitialized() const;
-
-  // Encodes the input string to the output stream using the table's Huffman
-  // context.
-  void EncodeString(SpdyStringPiece in, HpackOutputStream* out) const;
-
-  // Returns the encoded size of the input string.
-  size_t EncodedSize(SpdyStringPiece in) const;
-
-  // Decodes symbols from |in| into |out|, using the support for generic (any)
-  // huffman tables, not just those defined in the HPACK spec. It is the
-  // caller's responsibility to ensure |out| has reserved a sufficient buffer to
-  // hold decoded output. GenericDecodeString() halts when |in| runs out of
-  // input, in which case true is returned. It also halts (returning false) if
-  // an invalid Huffman code prefix is read, or if |out_capacity| would
-  // otherwise be overflowed.
-  // DEPRECATED: HpackHuffmanDecoder is now used for decoding strings encoded
-  // according to the Huffman Table in the HPACK spec.
-  bool GenericDecodeString(HpackInputStream* in, SpdyString* out) const;
-
-  // Returns the estimate of dynamically allocated memory in bytes.
-  size_t EstimateMemoryUsage() const;
-
- private:
-  // Expects symbols ordered on length & ID ascending.
-  void BuildDecodeTables(const std::vector<Symbol>& symbols);
-
-  // Expects symbols ordered on ID ascending.
-  void BuildEncodeTable(const std::vector<Symbol>& symbols);
-
-  // Adds a new DecodeTable with the argument prefix & indexed length.
-  // Returns the new table index.
-  uint8_t AddDecodeTable(uint8_t prefix, uint8_t indexed);
-
-  const DecodeEntry& Entry(const DecodeTable& table, uint32_t index) const;
-
-  void SetEntry(const DecodeTable& table,
-                uint32_t index,
-                const DecodeEntry& entry);
-
-  std::vector<DecodeTable> decode_tables_;
-  std::vector<DecodeEntry> decode_entries_;
-
-  // Symbol code and code length, in ascending symbol ID order.
-  // Codes are stored in the most-significant bits of the word.
-  std::vector<uint32_t> code_by_id_;
-  std::vector<uint8_t> length_by_id_;
-
-  // The first 8 bits of the longest code. Applied when generating padding bits.
-  uint8_t pad_bits_;
-
-  // If initialization fails, preserve the symbol ID which failed validation
-  // for examination in tests.
-  uint16_t failed_symbol_id_;
-};
-
-}  // namespace net
-
-#endif  // NET_SPDY_HPACK_HPACK_HUFFMAN_TABLE_H_