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 string
  26 import getopt
  27
  28 FS = ''
  29 SCRIPT = []
  30 AFLAG = 0
  31 CFLAG = 0
  32 DFLAG = 0
  33 NFLAG = 0
  34 PFLAG = 0
  35
  36 try:
  37     optlist, ARGS = getopt.getopt(sys.argv[1:], 'acde:F:np')
  38 except getopt.error, msg:
  39     sys.stderr.write(sys.argv[0] + ': ' + msg + '\n')
  40     sys.exit(2)
  41
  42 for option, optarg in optlist:
  43     if option == '-a':
  44         AFLAG = 1
  45     elif option == '-c':
  46         CFLAG = 1
  47     elif option == '-d':
  48         DFLAG = 1
  49     elif option == '-e':
  50         for line in string.splitfields(optarg, '\n'):
  51             SCRIPT.append(line)
  52     elif option == '-F':
  53         FS = optarg
  54     elif option == '-n':
  55         NFLAG = 1
  56         PFLAG = 0
  57     elif option == '-p':
  58         NFLAG = 1
  59         PFLAG = 1
  60     else:
  61         print option, 'not recognized???'
  62
  63 if not ARGS: ARGS.append('-')
  64
  65 if not SCRIPT:
  66     if ARGS[0] == '-':
  67         fp = sys.stdin
  68     else:
  69         fp = open(ARGS[0], 'r')
  70     while 1:
  71         line = fp.readline()
  72         if not line: break
  73         SCRIPT.append(line[:-1])
  74     del fp
  75     del ARGS[0]
  76     if not ARGS: ARGS.append('-')
  77
  78 if CFLAG:
  79     prologue = ['if 0:']
  80     epilogue = []
  81 elif NFLAG:
  82     # Note that it is on purpose that AFLAG and PFLAG are
  83     # tested dynamically each time through the loop
  84     prologue = [ \
  85             'LINECOUNT = 0', \
  86             'for FILE in ARGS:', \
  87             '   \tif FILE == \'-\':', \
  88             '   \t   \tFP = sys.stdin', \
  89             '   \telse:', \
  90             '   \t   \tFP = open(FILE, \'r\')', \
  91             '   \tLINENO = 0', \
  92             '   \twhile 1:', \
  93             '   \t   \tLINE = FP.readline()', \
  94             '   \t   \tif not LINE: break', \
  95             '   \t   \tLINENO = LINENO + 1', \
  96             '   \t   \tLINECOUNT = LINECOUNT + 1', \
  97             '   \t   \tL = LINE[:-1]', \
  98             '   \t   \taflag = AFLAG', \
  99             '   \t   \tif aflag:', \
 100             '   \t   \t   \tif FS: F = string.splitfields(L, FS)', \
 101             '   \t   \t   \telse: F = string.split(L)' \
 102             ]
 103     epilogue = [ \
 104             '   \t   \tif not PFLAG: continue', \
 105             '   \t   \tif aflag:', \
 106             '   \t   \t   \tif FS: print string.joinfields(F, FS)', \
 107             '   \t   \t   \telse: print string.join(F)', \
 108             '   \t   \telse: print L', \
 109             ]
 110 else:
 111     prologue = ['if 1:']
 112     epilogue = []
 113
 114 # Note that we indent using tabs only, so that any indentation style
 115 # used in 'command' will come out right after re-indentation.
 116
 117 program = string.joinfields(prologue, '\n') + '\n'
 118 for line in SCRIPT:
 119     program = program + ('   \t   \t' + line + '\n')
 120 program = program + (string.joinfields(epilogue, '\n') + '\n')
 121
 122 import tempfile
 123 fp = tempfile.NamedTemporaryFile()
 124 fp.write(program)
 125 fp.flush()
 126 if DFLAG:
 127     import pdb
 128     pdb.run('execfile(%r)' % (tfn,))
 129 else:
 130     execfile(tfn)