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+/*
+ * A C++ I/O streams interface to the zlib gz* functions
+ *
+ * by Ludwig Schwardt <schwardt@sun.ac.za>
+ * original version by Kevin Ruland <kevin@rodin.wustl.edu>
+ *
+ * This version is standard-compliant and compatible with gcc 3.x.
+ */
+
+#ifndef ZFSTREAM_H
+#define ZFSTREAM_H
+
+#include <istream> // not iostream, since we don't need cin/cout
+#include <ostream>
+#include "zlib.h"
+
+/*****************************************************************************/
+
+/**
+ * @brief Gzipped file stream buffer class.
+ *
+ * This class implements basic_filebuf for gzipped files. It doesn't yet support
+ * seeking (allowed by zlib but slow/limited), putback and read/write access
+ * (tricky). Otherwise, it attempts to be a drop-in replacement for the standard
+ * file streambuf.
+*/
+class gzfilebuf : public std::streambuf
+{
+public:
+ // Default constructor.
+ gzfilebuf();
+
+ // Destructor.
+ virtual
+ ~gzfilebuf();
+
+ /**
+ * @brief Set compression level and strategy on the fly.
+ * @param comp_level Compression level (see zlib.h for allowed values)
+ * @param comp_strategy Compression strategy (see zlib.h for allowed values)
+ * @return Z_OK on success, Z_STREAM_ERROR otherwise.
+ *
+ * Unfortunately, these parameters cannot be modified separately, as the
+ * previous zfstream version assumed. Since the strategy is seldom changed,
+ * it can default and setcompression(level) then becomes like the old
+ * setcompressionlevel(level).
+ */
+ int
+ setcompression(int comp_level,
+ int comp_strategy = Z_DEFAULT_STRATEGY);
+
+ /**
+ * @brief Check if file is open.
+ * @return True if file is open.
+ */
+ bool
+ is_open() const { return (file != NULL); }
+
+ /**
+ * @brief Open gzipped file.
+ * @param name File name.
+ * @param mode Open mode flags.
+ * @return @c this on success, NULL on failure.
+ */
+ gzfilebuf*
+ open(const char* name,
+ std::ios_base::openmode mode);
+
+ /**
+ * @brief Attach to already open gzipped file.
+ * @param fd File descriptor.
+ * @param mode Open mode flags.
+ * @return @c this on success, NULL on failure.
+ */
+ gzfilebuf*
+ attach(int fd,
+ std::ios_base::openmode mode);
+
+ /**
+ * @brief Close gzipped file.
+ * @return @c this on success, NULL on failure.
+ */
+ gzfilebuf*
+ close();
+
+protected:
+ /**
+ * @brief Convert ios open mode int to mode string used by zlib.
+ * @return True if valid mode flag combination.
+ */
+ bool
+ open_mode(std::ios_base::openmode mode,
+ char* c_mode) const;
+
+ /**
+ * @brief Number of characters available in stream buffer.
+ * @return Number of characters.
+ *
+ * This indicates number of characters in get area of stream buffer.
+ * These characters can be read without accessing the gzipped file.
+ */
+ virtual std::streamsize
+ showmanyc();
+
+ /**
+ * @brief Fill get area from gzipped file.
+ * @return First character in get area on success, EOF on error.
+ *
+ * This actually reads characters from gzipped file to stream
+ * buffer. Always buffered.
+ */
+ virtual int_type
+ underflow();
+
+ /**
+ * @brief Write put area to gzipped file.
+ * @param c Extra character to add to buffer contents.
+ * @return Non-EOF on success, EOF on error.
+ *
+ * This actually writes characters in stream buffer to
+ * gzipped file. With unbuffered output this is done one
+ * character at a time.
+ */
+ virtual int_type
+ overflow(int_type c = traits_type::eof());
+
+ /**
+ * @brief Installs external stream buffer.
+ * @param p Pointer to char buffer.
+ * @param n Size of external buffer.
+ * @return @c this on success, NULL on failure.
+ *
+ * Call setbuf(0,0) to enable unbuffered output.
+ */
+ virtual std::streambuf*
+ setbuf(char_type* p,
+ std::streamsize n);
+
+ /**
+ * @brief Flush stream buffer to file.
+ * @return 0 on success, -1 on error.
+ *
+ * This calls underflow(EOF) to do the job.
+ */
+ virtual int
+ sync();
+
+//
+// Some future enhancements
+//
+// virtual int_type uflow();
+// virtual int_type pbackfail(int_type c = traits_type::eof());
+// virtual pos_type
+// seekoff(off_type off,
+// std::ios_base::seekdir way,
+// std::ios_base::openmode mode = std::ios_base::in|std::ios_base::out);
+// virtual pos_type
+// seekpos(pos_type sp,
+// std::ios_base::openmode mode = std::ios_base::in|std::ios_base::out);
+
+private:
+ /**
+ * @brief Allocate internal buffer.
+ *
+ * This function is safe to call multiple times. It will ensure
+ * that a proper internal buffer exists if it is required. If the
+ * buffer already exists or is external, the buffer pointers will be
+ * reset to their original state.
+ */
+ void
+ enable_buffer();
+
+ /**
+ * @brief Destroy internal buffer.
+ *
+ * This function is safe to call multiple times. It will ensure
+ * that the internal buffer is deallocated if it exists. In any
+ * case, it will also reset the buffer pointers.
+ */
+ void
+ disable_buffer();
+
+ /**
+ * Underlying file pointer.
+ */
+ gzFile file;
+
+ /**
+ * Mode in which file was opened.
+ */
+ std::ios_base::openmode io_mode;
+
+ /**
+ * @brief True if this object owns file descriptor.
+ *
+ * This makes the class responsible for closing the file
+ * upon destruction.
+ */
+ bool own_fd;
+
+ /**
+ * @brief Stream buffer.
+ *
+ * For simplicity this remains allocated on the free store for the
+ * entire life span of the gzfilebuf object, unless replaced by setbuf.
+ */
+ char_type* buffer;
+
+ /**
+ * @brief Stream buffer size.
+ *
+ * Defaults to system default buffer size (typically 8192 bytes).
+ * Modified by setbuf.
+ */
+ std::streamsize buffer_size;
+
+ /**
+ * @brief True if this object owns stream buffer.
+ *
+ * This makes the class responsible for deleting the buffer
+ * upon destruction.
+ */
+ bool own_buffer;
+};
+
+/*****************************************************************************/
+
+/**
+ * @brief Gzipped file input stream class.
+ *
+ * This class implements ifstream for gzipped files. Seeking and putback
+ * is not supported yet.
+*/
+class gzifstream : public std::istream
+{
+public:
+ // Default constructor
+ gzifstream();
+
+ /**
+ * @brief Construct stream on gzipped file to be opened.
+ * @param name File name.
+ * @param mode Open mode flags (forced to contain ios::in).
+ */
+ explicit
+ gzifstream(const char* name,
+ std::ios_base::openmode mode = std::ios_base::in);
+
+ /**
+ * @brief Construct stream on already open gzipped file.
+ * @param fd File descriptor.
+ * @param mode Open mode flags (forced to contain ios::in).
+ */
+ explicit
+ gzifstream(int fd,
+ std::ios_base::openmode mode = std::ios_base::in);
+
+ /**
+ * Obtain underlying stream buffer.
+ */
+ gzfilebuf*
+ rdbuf() const
+ { return const_cast<gzfilebuf*>(&sb); }
+
+ /**
+ * @brief Check if file is open.
+ * @return True if file is open.
+ */
+ bool
+ is_open() { return sb.is_open(); }
+
+ /**
+ * @brief Open gzipped file.
+ * @param name File name.
+ * @param mode Open mode flags (forced to contain ios::in).
+ *
+ * Stream will be in state good() if file opens successfully;
+ * otherwise in state fail(). This differs from the behavior of
+ * ifstream, which never sets the state to good() and therefore
+ * won't allow you to reuse the stream for a second file unless
+ * you manually clear() the state. The choice is a matter of
+ * convenience.
+ */
+ void
+ open(const char* name,
+ std::ios_base::openmode mode = std::ios_base::in);
+
+ /**
+ * @brief Attach to already open gzipped file.
+ * @param fd File descriptor.
+ * @param mode Open mode flags (forced to contain ios::in).
+ *
+ * Stream will be in state good() if attach succeeded; otherwise
+ * in state fail().
+ */
+ void
+ attach(int fd,
+ std::ios_base::openmode mode = std::ios_base::in);
+
+ /**
+ * @brief Close gzipped file.
+ *
+ * Stream will be in state fail() if close failed.
+ */
+ void
+ close();
+
+private:
+ /**
+ * Underlying stream buffer.
+ */
+ gzfilebuf sb;
+};
+
+/*****************************************************************************/
+
+/**
+ * @brief Gzipped file output stream class.
+ *
+ * This class implements ofstream for gzipped files. Seeking and putback
+ * is not supported yet.
+*/
+class gzofstream : public std::ostream
+{
+public:
+ // Default constructor
+ gzofstream();
+
+ /**
+ * @brief Construct stream on gzipped file to be opened.
+ * @param name File name.
+ * @param mode Open mode flags (forced to contain ios::out).
+ */
+ explicit
+ gzofstream(const char* name,
+ std::ios_base::openmode mode = std::ios_base::out);
+
+ /**
+ * @brief Construct stream on already open gzipped file.
+ * @param fd File descriptor.
+ * @param mode Open mode flags (forced to contain ios::out).
+ */
+ explicit
+ gzofstream(int fd,
+ std::ios_base::openmode mode = std::ios_base::out);
+
+ /**
+ * Obtain underlying stream buffer.
+ */
+ gzfilebuf*
+ rdbuf() const
+ { return const_cast<gzfilebuf*>(&sb); }
+
+ /**
+ * @brief Check if file is open.
+ * @return True if file is open.
+ */
+ bool
+ is_open() { return sb.is_open(); }
+
+ /**
+ * @brief Open gzipped file.
+ * @param name File name.
+ * @param mode Open mode flags (forced to contain ios::out).
+ *
+ * Stream will be in state good() if file opens successfully;
+ * otherwise in state fail(). This differs from the behavior of
+ * ofstream, which never sets the state to good() and therefore
+ * won't allow you to reuse the stream for a second file unless
+ * you manually clear() the state. The choice is a matter of
+ * convenience.
+ */
+ void
+ open(const char* name,
+ std::ios_base::openmode mode = std::ios_base::out);
+
+ /**
+ * @brief Attach to already open gzipped file.
+ * @param fd File descriptor.
+ * @param mode Open mode flags (forced to contain ios::out).
+ *
+ * Stream will be in state good() if attach succeeded; otherwise
+ * in state fail().
+ */
+ void
+ attach(int fd,
+ std::ios_base::openmode mode = std::ios_base::out);
+
+ /**
+ * @brief Close gzipped file.
+ *
+ * Stream will be in state fail() if close failed.
+ */
+ void
+ close();
+
+private:
+ /**
+ * Underlying stream buffer.
+ */
+ gzfilebuf sb;
+};
+
+/*****************************************************************************/
+
+/**
+ * @brief Gzipped file output stream manipulator class.
+ *
+ * This class defines a two-argument manipulator for gzofstream. It is used
+ * as base for the setcompression(int,int) manipulator.
+*/
+template<typename T1, typename T2>
+ class gzomanip2
+ {
+ public:
+ // Allows insertor to peek at internals
+ template <typename Ta, typename Tb>
+ friend gzofstream&
+ operator<<(gzofstream&,
+ const gzomanip2<Ta,Tb>&);
+
+ // Constructor
+ gzomanip2(gzofstream& (*f)(gzofstream&, T1, T2),
+ T1 v1,
+ T2 v2);
+ private:
+ // Underlying manipulator function
+ gzofstream&
+ (*func)(gzofstream&, T1, T2);
+
+ // Arguments for manipulator function
+ T1 val1;
+ T2 val2;
+ };
+
+/*****************************************************************************/
+
+// Manipulator function thunks through to stream buffer
+inline gzofstream&
+setcompression(gzofstream &gzs, int l, int s = Z_DEFAULT_STRATEGY)
+{
+ (gzs.rdbuf())->setcompression(l, s);
+ return gzs;
+}
+
+// Manipulator constructor stores arguments
+template<typename T1, typename T2>
+ inline
+ gzomanip2<T1,T2>::gzomanip2(gzofstream &(*f)(gzofstream &, T1, T2),
+ T1 v1,
+ T2 v2)
+ : func(f), val1(v1), val2(v2)
+ { }
+
+// Insertor applies underlying manipulator function to stream
+template<typename T1, typename T2>
+ inline gzofstream&
+ operator<<(gzofstream& s, const gzomanip2<T1,T2>& m)
+ { return (*m.func)(s, m.val1, m.val2); }
+
+// Insert this onto stream to simplify setting of compression level
+inline gzomanip2<int,int>
+setcompression(int l, int s = Z_DEFAULT_STRATEGY)
+{ return gzomanip2<int,int>(&setcompression, l, s); }
+
+#endif // ZFSTREAM_H
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