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1"""ndiff [-q] file1 file2
2    or
3ndiff (-r1 | -r2) < ndiff_output > file1_or_file2
4
5Print a human-friendly file difference report to stdout.  Both inter-
6and intra-line differences are noted.  In the second form, recreate file1
7(-r1) or file2 (-r2) on stdout, from an ndiff report on stdin.
8
9In the first form, if -q ("quiet") is not specified, the first two lines
10of output are
11
12-: file1
13+: file2
14
15Each remaining line begins with a two-letter code:
16
17    "- "    line unique to file1
18    "+ "    line unique to file2
19    "  "    line common to both files
20    "? "    line not present in either input file
21
22Lines beginning with "? " attempt to guide the eye to intraline
23differences, and were not present in either input file.  These lines can be
24confusing if the source files contain tab characters.
25
26The first file can be recovered by retaining only lines that begin with
27"  " or "- ", and deleting those 2-character prefixes; use ndiff with -r1.
28
29The second file can be recovered similarly, but by retaining only "  " and
30"+ " lines; use ndiff with -r2; or, on Unix, the second file can be
31recovered by piping the output through
32
33    sed -n '/^[+ ] /s/^..//p'
34"""
35
36__version__ = 1, 7, 0
37
38import difflib, sys
39
40def fail(msg):
41    out = sys.stderr.write
42    out(msg + "\n\n")
43    out(__doc__)
44    return 0
45
46# open a file & return the file object; gripe and return 0 if it
47# couldn't be opened
48def fopen(fname):
49    try:
50        return open(fname)
51    except IOError as detail:
52        return fail("couldn't open " + fname + ": " + str(detail))
53
54# open two files & spray the diff to stdout; return false iff a problem
55def fcompare(f1name, f2name):
56    f1 = fopen(f1name)
57    f2 = fopen(f2name)
58    if not f1 or not f2:
59        return 0
60
61    a = f1.readlines(); f1.close()
62    b = f2.readlines(); f2.close()
63    for line in difflib.ndiff(a, b):
64        print(line, end=' ')
65
66    return 1
67
68# crack args (sys.argv[1:] is normal) & compare;
69# return false iff a problem
70
71def main(args):
72    import getopt
73    try:
74        opts, args = getopt.getopt(args, "qr:")
75    except getopt.error as detail:
76        return fail(str(detail))
77    noisy = 1
78    qseen = rseen = 0
79    for opt, val in opts:
80        if opt == "-q":
81            qseen = 1
82            noisy = 0
83        elif opt == "-r":
84            rseen = 1
85            whichfile = val
86    if qseen and rseen:
87        return fail("can't specify both -q and -r")
88    if rseen:
89        if args:
90            return fail("no args allowed with -r option")
91        if whichfile in ("1", "2"):
92            restore(whichfile)
93            return 1
94        return fail("-r value must be 1 or 2")
95    if len(args) != 2:
96        return fail("need 2 filename args")
97    f1name, f2name = args
98    if noisy:
99        print('-:', f1name)
100        print('+:', f2name)
101    return fcompare(f1name, f2name)
102
103# read ndiff output from stdin, and print file1 (which=='1') or
104# file2 (which=='2') to stdout
105
106def restore(which):
107    restored = difflib.restore(sys.stdin.readlines(), which)
108    sys.stdout.writelines(restored)
109
110if __name__ == '__main__':
111    main(sys.argv[1:])
112