include/wx/file.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        file.cpp
   3 // Purpose:     wxFile - encapsulates low-level "file descriptor"
   4 //              wxTempFile - safely replace the old file
   5 // Author:      Vadim Zeitlin
   6 // Modified by:
   7 // Created:     29/01/98
   8 // RCS-ID:      $Id$
   9 // Copyright:   (c) 1998 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr>
  10 // Licence:     wxWindows license
  11 /////////////////////////////////////////////////////////////////////////////
  12
  13 #ifndef   __FILEH__
  14 #define   __FILEH__
  15
  16 #ifdef __GNUG__
  17 #pragma interface "file.h"
  18 #endif
  19
  20 #include  "wx/string.h"
  21 #include  "wx/filefn.h"
  22
  23 // ----------------------------------------------------------------------------
  24 // constants
  25 // ----------------------------------------------------------------------------
  26
  27 // error return value for Seek() functions
  28 const off_t ofsInvalid = (off_t)-1;
  29
  30 // ----------------------------------------------------------------------------
  31 // class wxFile: raw file IO
  32 //
  33 // NB: for space efficiency this class has no virtual functions, including
  34 //     dtor which is _not_ virtual, so it shouldn't be used as a base class.
  35 // ----------------------------------------------------------------------------
  36 class WXDLLEXPORT wxFile
  37 {
  38 public:
  39   // more file constants
  40   // -------------------
  41
  42     // opening mode
  43   enum OpenMode { read, write, read_write, write_append };
  44     // standard values for file descriptor
  45   enum { fd_invalid = -1, fd_stdin, fd_stdout, fd_stderr };
  46
  47   // static functions
  48   // ----------------
  49   static bool Exists(const char *sz);  // also checks it's a regular file
  50
  51   // ctors
  52   // -----
  53     // def ctor
  54   wxFile() { m_fd = fd_invalid; }
  55     // open specified file (may fail, use IsOpened())
  56   wxFile(const char *szFileName, OpenMode mode = read);
  57     // attach to (already opened) file
  58   wxFile(int fd) { m_fd = fd; }
  59
  60   // open/close
  61   bool Create(const char *szFileName, bool bOverwrite = FALSE);
  62   bool Open(const char *szFileName, OpenMode mode = read);
  63   bool Close();  // Close is a NOP if not opened
  64
  65   // assign an existing file descriptor and get it back from wxFile object
  66   void Attach(int fd) { Close(); m_fd = fd; }
  67   void Detach()       { m_fd = fd_invalid;  }
  68   int  fd() const { return m_fd; }
  69
  70   // read/write (unbuffered)
  71     // returns number of bytes read or ofsInvalid on error
  72   off_t Read(void *pBuf, off_t nCount);
  73     // returns true on success
  74   uint Write(const void *pBuf, uint nCount);
  75     // returns true on success
  76   bool Write(const wxString& s) { return Write(s.c_str(), s.Len()) != 0; }
  77     // flush data not yet written
  78   bool Flush();
  79
  80   // file pointer operations (return ofsInvalid on failure)
  81     // move ptr ofs bytes related to start/current off_t/end of file
  82   off_t Seek(off_t ofs, wxSeekMode mode = wxFromStart);
  83     // move ptr to ofs bytes before the end
  84   off_t SeekEnd(off_t ofs = 0) { return Seek(ofs, wxFromEnd); }
  85     // get current off_t
  86   off_t Tell() const;
  87     // get current file length
  88   off_t Length() const;
  89
  90   // simple accessors
  91     // is file opened?
  92   bool IsOpened() const { return m_fd != fd_invalid; }
  93     // is end of file reached?
  94   bool Eof() const;
  95     // is an error occured?
  96   bool Error() const { return m_error; }
  97
  98   // dtor closes the file if opened
  99  ~wxFile();
 100
 101 private:
 102   // copy ctor and assignment operator are private because
 103   // it doesn't make sense to copy files this way:
 104   // attempt to do it will provoke a compile-time error.
 105   wxFile(const wxFile&);
 106   wxFile& operator=(const wxFile&);
 107
 108   int m_fd; // file descriptor or INVALID_FD if not opened
 109   bool m_error; // error memory
 110 };
 111
 112 // ----------------------------------------------------------------------------
 113 // class wxTempFile: if you want to replace another file, create an instance
 114 // of wxTempFile passing the name of the file to be replaced to the ctor. Then
 115 // you can write to wxTempFile and call Commit() function to replace the old
 116 // file (and close this one) or call Discard() to cancel the modification. If
 117 // you call neither of them, dtor will call Discard().
 118 // ----------------------------------------------------------------------------
 119 class wxTempFile
 120 {
 121 public:
 122   // ctors
 123     // default
 124   wxTempFile() { }
 125     // associates the temp file with the file to be replaced and opens it
 126   wxTempFile(const wxString& strName);
 127
 128   // open the temp file (strName is the name of file to be replaced)
 129   bool Open(const wxString& strName);
 130
 131   // is the file opened?
 132   bool IsOpened() const { return m_file.IsOpened(); }
 133
 134   // I/O (both functions return true on success, false on failure)
 135   bool Write(const void *p, uint n) { return m_file.Write(p, n) != 0; }
 136   bool Write(const wxString& str)   { return m_file.Write(str); }
 137
 138   // different ways to close the file
 139     // validate changes and delete the old file of name m_strName
 140   bool Commit();
 141     // discard changes
 142   void Discard();
 143
 144   // dtor calls Discard() if file is still opened
 145  ~wxTempFile();
 146
 147 private:
 148   wxString  m_strName,  // name of the file to replace in Commit()
 149             m_strTemp;  // temporary file name
 150   wxFile    m_file;     // the temporary file
 151 };
 152
 153 #endif
 154         // __FILEH__