apt-pkg/tagfile.h

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: tagfile.h,v 1.12 1998/12/07 07:26:23 jgg Exp $
   4 /* ######################################################################
   5
   6    Fast scanner for RFC-822 type header information
   7
   8    This parser handles Debian package files (and others). Their form is
   9    RFC-822 type header fields in groups seperated by a blank line.
  10
  11    The parser reads the file and provides methods to step linearly
  12    over it or to jump to a pre-recorded start point and read that record.
  13
  14    A second class is used to perform pre-parsing of the record. It works
  15    by indexing the start of each header field and providing lookup
  16    functions for header fields.
  17
  18    ##################################################################### */
  19                                                                         /*}}}*/
  20 // Header section: pkglib
  21 #ifndef PKGLIB_TAGFILE_H
  22 #define PKGLIB_TAGFILE_H
  23
  24 #ifdef __GNUG__
  25 #pragma interface "apt-pkg/tagfile.h"
  26 #endif
  27
  28 #include <apt-pkg/fileutl.h>
  29
  30 class pkgTagSection
  31 {
  32    const char *Section;
  33    const char *Stop;
  34
  35    // We have a limit of 256 tags per section.
  36    unsigned short Indexes[256];
  37    unsigned short AlphaIndexes[26 + 26*26];
  38
  39    unsigned int TagCount;
  40
  41    public:
  42
  43    inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
  44    inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
  45
  46    bool Find(const char *Tag,const char *&Start, const char *&End);
  47    string FindS(const char *Tag);
  48    unsigned int FindI(const char *Tag);
  49    bool Scan(const char *Start,unsigned long MaxLength);
  50    inline unsigned long size() {return Stop - Section;};
  51
  52    inline unsigned int Count() {return TagCount;};
  53    inline void Get(const char *&Start,const char *&Stop,unsigned int I)
  54                    {Start = Section + Indexes[I]; Stop = Section + Indexes[I+1];}
  55
  56    inline void GetSection(const char *&Start,const char *&Stop)
  57    {
  58       Start = Section;
  59       Stop = this->Stop;
  60    };
  61
  62    pkgTagSection() : Section(0), Stop(0) {};
  63 };
  64
  65 class pkgTagFile
  66 {
  67    FileFd &Fd;
  68    char *Buffer;
  69    char *Start;
  70    char *End;
  71    unsigned long Left;
  72    unsigned long iOffset;
  73    unsigned long Size;
  74
  75    bool Fill();
  76
  77    public:
  78
  79    bool Step(pkgTagSection &Section);
  80    inline unsigned long Offset() {return iOffset;};
  81    bool Jump(pkgTagSection &Tag,unsigned long Offset);
  82
  83    pkgTagFile(FileFd &F,unsigned long Size = 32*1024);
  84 };
  85
  86 #endif