ReadIndex.h

   1 #ifndef READINDEX_H_
   2 #define READINDEX_H_
   3
   4 #include<cstdio>
   5 #include<cstdlib>
   6 #include<iostream>
   7 #include<fstream>
   8
   9 #include "utils.h"
  10
  11 struct ReadIndex {
  12         READ_INT_TYPE nReads;
  13         int gap, nPos;
  14         std::streampos *index;
  15
  16         ReadIndex () {
  17                 nReads = 0; gap = nPos = 0;
  18                 index = NULL;
  19         }
  20
  21         ReadIndex(const char* readF) {
  22                 char indexF[STRLEN];
  23                 std::ifstream fin;
  24
  25                 sprintf(indexF, "%s.ridx", readF);
  26                 fin.open(indexF, std::ios::binary);
  27                 if (!fin.is_open()) { fprintf(stderr, "Cannot open %s! It may not exist.\n", indexF); exit(-1); }
  28
  29                 nReads = 0; gap = nPos = 0;
  30                 index = NULL;
  31                 if (fin.is_open()) {
  32                         fin.read((char*)&nReads, sizeof(nReads));
  33                         fin.read((char*)&gap, sizeof(gap));
  34                         fin.read((char*)&nPos, sizeof(nPos));
  35                         index = new std::streampos[nPos];
  36                         for (int i = 0; i < nPos; i++) {
  37                                 fin.read((char*)&index[i], sizeof(std::streampos));
  38                         }
  39                 }
  40         }
  41
  42         ~ReadIndex() {
  43                 nReads = 0; gap = nPos = 0;
  44                 if (index != NULL) delete[] index;
  45         }
  46
  47         //rid  0-based , return crid : current seeked rid
  48         READ_INT_TYPE locate(READ_INT_TYPE rid, std::ifstream& out) {
  49                 if (index == NULL) {
  50                         out.seekg(0, std::ios::beg);
  51                         return 0;
  52                 }
  53                 assert(rid >= 0 && rid < nReads);
  54                 out.seekg(index[rid / gap]);
  55                 return (rid / gap) * gap;
  56         }
  57 };
  58
  59 #endif /* READINDEX_H_ */