tools_tinycdb.py

Using the tinycdb index files.

#!/usr/bin/python
 
 
import msparser
import sys
import re
 
def main() :
  # This next line just creates the object. It doesn't open a file
  # The 'source file' is (unusually!) this Python script (sys.argv[0]), 
  # meaning that if this file is changed, the index will be re-created.
  version = "1.1"
  sourceFile = sys.argv[0]
  cdbname = sys.argv[0] + '.cdb'
  cdb = msparser.ms_tinycdb(cdbname, version, sourceFile)
 
  if not cdb.isValid() :
    showErrors(cdb)
    return 1
 
  if not cdb.openIndexFile(True) :
    if cdb.isPossibleToCreate() :
      print("Creating file because: %s" % cdb.getLastErrorString())
      cdb.prepareToCreate()
      cdb.saveValueForKey("Hello", "world")
    
      # It is unusual to use the same key for 2 values, but it can be done:
      cdb.saveValueForKey("HELP", "me")
      cdb.saveValueForKey("HELP", "me too")
    
      # Example of saving a file offset. Can use a binary offset into the
      # file with the ms_tincycdb.saveFileOffsetForKey() function, but this
      # example uses saveIntForKey and a line offset. This facile example
      # uses this source file as the input!
      # and saves an offset to THIS line!
      try :
          fh = open(sys.argv[0], 'r')
      except IOError as err:
        errno, strerror = err.args
        print("Cannot open " + sys.argv[0] + " for reading: " + strerror)
        return 1
        sys.exit(1)
      line_nr = 1
      for line in fh :
        if re.search('\s*# and saves an.*', line) :
            break
 
        line_nr += 1
 
      fh.close();
      
      cdb.saveIntForKey("Line", line_nr)
      cdb.finishCreate()
 
      
  if cdb.isValid() :
    print("Retrieving value for Hello    : %s" % cdb.getValueFromKey("Hello"))
    print("Retrieving 1st value for HELP : %s" % cdb.getValueFromKey("HELP", 0))
    print("Retrieving 2nd value for HELP : %s" % cdb.getValueFromKey("HELP", 1))
 
    # Check saved line index  
    try :
        fh = open(sys.argv[0], 'r')
    except IOError as err:
        errno, strerror = err.args
        print("Cannot open " + sys.argv[0] + " for reading: " + strerror)
        return 1
 
    line_nr = cdb.getIntFromKey("Line")
 
    i = 1
    for line in fh :
        if i == line_nr : break
        i += 1
 
    print("Testing line index. Line " + str(line_nr + 1) + " : " + line)
    fh.close()
  else :
    showErrors(cdb)
 
 
def showErrors(obj) :
    err = obj.getErrorHandler()
 
    for i in range(1, 1 + err.getNumberOfErrors()) :
        print("Error number: %d (%d times): %s" % (err.getErrorNumber(i), err.getErrorRepeats(i) + 1, err.getErrorString(i))) 
            
    print(" ")
    obj.clearAllErrors()
 
if __name__ == "__main__" :
    sys.exit(main())