#define LLVM_SUPPORT_COMPRESSOR_H
#include "llvm/Support/DataTypes.h"
-#include <ostream>
+#include <iosfwd>
namespace llvm {
- /// This class provides an abstraction for compressing a block of memory using
- /// a standard compression utility such as bzip2 or libz. This interface
- /// allows us to abstract the notion of compression and deal with alternate
- /// compression scheme availability depending on the configured platform. This
- /// facility will always favor a bzip2 implementation if its available.
- /// Otherwise, libz will be used if it is available. If neither zlib nor bzip2
- /// are available, a very simple algorithm provided by the Compressor class
- /// will be used. The type of compression used can be determined by inspecting
- /// the first byte of the compressed output. ASCII values '0', '1', and '2',
- /// denote the compression type as given in the Algorithm enumeration below.
- /// The Compressor is intended for use with memory mapped files where the
- /// entire data block to be compressed or decompressed is available in
- /// memory. However, output can be gathered in repeated calls to a callback.
+ /// This class provides an abstraction for compression and decompression of
+ /// a block of memory. The algorithm used here is currently bzip2 but that
+ /// may change without notice. Should newer algorithms prove to compress
+ /// bytecode better than bzip2, that newer algorithm will be added, but won't
+ /// replace bzip2. This interface allows us to abstract the notion of
+ /// compression and deal with alternate compression schemes over time.
+ /// The type of compression used can be determined by inspecting the
+ /// first byte of the compressed output. Currently value '0' means no
+ /// compression was used (for very small files) and value '2' means bzip2
+ /// compression was used. The Compressor is intended for use with memory
+ /// mapped files where the entire data block to be compressed or decompressed
+ /// is available in memory. However, output can be gathered in repeated calls
+ /// to a callback. Utilities for sending compressed or decompressed output
+ /// to a stream or directly to a memory block are also provided.
/// @since 1.4
/// @brief An abstraction for memory to memory data (de)compression
class Compressor {
- /// @name Types
- /// @{
- public:
- enum Algorithm {
- COMP_TYPE_SIMPLE = '0', ///< Use simple but ubiquitous algorithm
- COMP_TYPE_ZLIB = '1', ///< Use zlib algorithm, if available
- COMP_TYPE_BZIP2 = '2', ///< Use bzip2 algorithm (preferred)
- };
-
- /// @}
/// @name High Level Interface
/// @{
public:
/// @throws std::string explaining error if a compression error occurs
/// @returns The size of the output buffer \p out.
/// @brief Compress memory to a new memory buffer.
- static uint64_t compressToNewBuffer(
+ static size_t compressToNewBuffer(
const char* in, ///< The buffer to be compressed
- unsigned size, ///< The size of the buffer to be compressed
- char*&out, ///< The returned output buffer
- Algorithm hint ///< Hint for type of compression to perform
- = COMP_TYPE_BZIP2
+ size_t size, ///< The size of the buffer to be compressed
+ char*&out ///< The returned output buffer
);
/// This method compresses a block of memory pointed to by \p in with
/// compression the caller would *prefer*.
/// @returns The amount of data written to \p out.
/// @brief Compress memory to a file.
- static uint64_t compressToStream(
+ static size_t compressToStream(
const char*in, ///< The buffer to be compressed
- unsigned size, ///< The size of the buffer to be compressed
- std::ostream& out, ///< The output stream to write data on
- Algorithm hint ///< Hint for type of compression to perform
- = COMP_TYPE_BZIP2
+ size_t size, ///< The size of the buffer to be compressed
+ std::ostream& out ///< The output stream to write data on
);
/// This method decompresses a block of memory pointed to by \p in with
/// by malloc. It is the caller's responsibility to free \p out.
/// @returns The size of the output buffer \p out.
/// @brief Decompress memory to a new memory buffer.
- static uint64_t decompressToNewBuffer(
+ static size_t decompressToNewBuffer(
const char *in, ///< The buffer to be decompressed
- unsigned size, ///< Size of the buffer to be decompressed
+ size_t size, ///< Size of the buffer to be decompressed
char*&out ///< The returned output buffer
);
/// this method.
/// @returns The amount of data written to \p out.
/// @brief Decompress memory to a stream.
- static uint64_t decompressToStream(
+ static size_t decompressToStream(
const char *in, ///< The buffer to be decompressed
- unsigned size, ///< Size of the buffer to be decompressed
+ size_t size, ///< Size of the buffer to be decompressed
std::ostream& out ///< The stream to write write data on
);
/// @returns 0 for success, 1 for failure
/// @throws nothing
/// @brief Output callback function type
- typedef unsigned (OutputDataCallback)(char*& buffer, unsigned& size,
+ typedef size_t (OutputDataCallback)(char*& buffer, size_t& size,
void* context);
/// This function does the compression work. The block of memory starting
/// @throws std::string if an error occurs
/// @returns the total size of the compressed data
/// @brief Compress a block of memory.
- static uint64_t compress(
+ static size_t compress(
const char* in, ///< The buffer to be compressed
- unsigned size, ///< The size of the buffer to be compressed
+ size_t size, ///< The size of the buffer to be compressed
OutputDataCallback* cb, ///< Call back for memory allocation
- Algorithm hint ///< Hint for type of compression to perform
- = COMP_TYPE_BZIP2,
- void* context ///< Context for callback
- = 0
+ void* context = 0 ///< Context for callback
);
/// This function does the decompression work. The block of memory
/// @throws std::string if an error occurs
/// @returns the total size of the decompressed data
/// @brief Decompress a block of memory.
- static uint64_t decompress(
+ static size_t decompress(
const char *in, ///< The buffer to be decompressed
- unsigned size, ///< Size of the buffer to be decompressed
+ size_t size, ///< Size of the buffer to be decompressed
OutputDataCallback* cb, ///< Call back for memory allocation
- void* context ///< Context for callback
- = 0
+ void* context = 0 ///< Context for callback
);
/// @}
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