Demo/scripts/pp.py

   1 #! /usr/bin/env python
   2
   3 # Emulate some Perl command line options.
   4 # Usage: pp [-a] [-c] [-d] [-e scriptline] [-F fieldsep] [-n] [-p] [file] ...
   5 # Where the options mean the following:
   6 #   -a            : together with -n or -p, splits each line into list F
   7 #   -c            : check syntax only, do not execute any code
   8 #   -d            : run the script under the debugger, pdb
   9 #   -e scriptline : gives one line of the Python script; may be repeated
  10 #   -F fieldsep   : sets the field separator for the -a option [not in Perl]
  11 #   -n            : runs the script for each line of input
  12 #   -p            : prints the line after the script has run
  13 # When no script lines have been passed, the first file argument
  14 # contains the script.  With -n or -p, the remaining arguments are
  15 # read as input to the script, line by line.  If a file is '-'
  16 # or missing, standard input is read.
  17
  18 # XXX To do:
  19 # - add -i extension option (change files in place)
  20 # - make a single loop over the files and lines (changes effect of 'break')?
  21 # - add an option to specify the record separator
  22 # - except for -n/-p, run directly from the file if at all possible
  23
  24 import sys
  25 import getopt
  26
  27 FS = ''
  28 SCRIPT = []
  29 AFLAG = 0
  30 CFLAG = 0
  31 DFLAG = 0
  32 NFLAG = 0
  33 PFLAG = 0
  34
  35 try:
  36     optlist, ARGS = getopt.getopt(sys.argv[1:], 'acde:F:np')
  37 except getopt.error, msg:
  38     sys.stderr.write('%s: %s\n' % (sys.argv[0], msg))
  39     sys.exit(2)
  40
  41 for option, optarg in optlist:
  42     if option == '-a':
  43         AFLAG = 1
  44     elif option == '-c':
  45         CFLAG = 1
  46     elif option == '-d':
  47         DFLAG = 1
  48     elif option == '-e':
  49         for line in optarg.split('\n'):
  50             SCRIPT.append(line)
  51     elif option == '-F':
  52         FS = optarg
  53     elif option == '-n':
  54         NFLAG = 1
  55         PFLAG = 0
  56     elif option == '-p':
  57         NFLAG = 1
  58         PFLAG = 1
  59     else:
  60         print option, 'not recognized???'
  61
  62 if not ARGS: ARGS.append('-')
  63
  64 if not SCRIPT:
  65     if ARGS[0] == '-':
  66         fp = sys.stdin
  67     else:
  68         fp = open(ARGS[0], 'r')
  69     while 1:
  70         line = fp.readline()
  71         if not line: break
  72         SCRIPT.append(line[:-1])
  73     del fp
  74     del ARGS[0]
  75     if not ARGS: ARGS.append('-')
  76
  77 if CFLAG:
  78     prologue = ['if 0:']
  79     epilogue = []
  80 elif NFLAG:
  81     # Note that it is on purpose that AFLAG and PFLAG are
  82     # tested dynamically each time through the loop
  83     prologue = [
  84             'LINECOUNT = 0',
  85             'for FILE in ARGS:',
  86             '   \tif FILE == \'-\':',
  87             '   \t   \tFP = sys.stdin',
  88             '   \telse:',
  89             '   \t   \tFP = open(FILE, \'r\')',
  90             '   \tLINENO = 0',
  91             '   \twhile 1:',
  92             '   \t   \tLINE = FP.readline()',
  93             '   \t   \tif not LINE: break',
  94             '   \t   \tLINENO = LINENO + 1',
  95             '   \t   \tLINECOUNT = LINECOUNT + 1',
  96             '   \t   \tL = LINE[:-1]',
  97             '   \t   \taflag = AFLAG',
  98             '   \t   \tif aflag:',
  99             '   \t   \t   \tif FS: F = L.split(FS)',
 100             '   \t   \t   \telse: F = L.split()'
 101             ]
 102     epilogue = [
 103             '   \t   \tif not PFLAG: continue',
 104             '   \t   \tif aflag:',
 105             '   \t   \t   \tif FS: print FS.join(F)',
 106             '   \t   \t   \telse: print \' \'.join(F)',
 107             '   \t   \telse: print L',
 108             ]
 109 else:
 110     prologue = ['if 1:']
 111     epilogue = []
 112
 113 # Note that we indent using tabs only, so that any indentation style
 114 # used in 'command' will come out right after re-indentation.
 115
 116 program = '\n'.join(prologue) + '\n'
 117 for line in SCRIPT:
 118     program += '   \t   \t' + line + '\n'
 119 program += '\n'.join(epilogue) + '\n'
 120
 121 import tempfile
 122 fp = tempfile.NamedTemporaryFile()
 123 fp.write(program)
 124 fp.flush()
 125 if DFLAG:
 126     import pdb
 127     pdb.run('execfile(%r)' % (fp.name,))
 128 else:
 129     execfile(fp.name)