1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
|
User Commands SIM(1)
NAME
sim - find similarities in C, Java, Pascal, Modula-2, Lisp,
Miranda or text files
SYNOPSIS
sim_c [ -[defFnpsS] -r N -w N -o F ] file ... [ / [ file ...
] ]
sim_c ...
sim_java ...
sim_pasc ...
sim_m2 ...
sim_lisp ...
sim_mira ...
sim_text ...
DESCRIPTION
Sim_c reads the C files file ... and looks for pieces of
text that are similar; two pieces of program text are simi-
lar if they only differ in layout, comment, identifiers and
the contents of numbers, strings and characters. If any
runs of sufficient length are found, they are reported on
standard output; the number of significant tokens in the run
is given between square brackets.
Sim_java does the same for Java, sim_pasc for Pascal, sim_m2
for Modula-2, sim_lisp for Lisp, and sim_mira for Miranda.
Sim_text works on arbitrary text; it is occasionally useful
on shell scripts.
The program can be used for finding copied pieces of code in
purportedly unrelated programs (with -s or -S), or for find-
ing accidentally duplicated code in larger projects (with
-f).
If a / is present between the input files, the latter are
divided into a group of "new" files (before the /) and a
group of "old" files; if there is no /, all files are "new".
Old files are never compared to each other. Since the simi-
larity tester reads the files several times, it cannot read
from standard input.
There are the following options:
-d The output is in a diff(1)-like format instead of the
default 2-column format.
-e Each file is compared to each file in isolation; this
will find all similarities between all texts involved,
regardless of duplicates.
-f Runs are restricted to pieces with balancing
parentheses, to isolate potential functions (C, Java,
Vrije Universiteit Last change: 2001/11/13 1
User Commands SIM(1)
Pascal, Modula-2 and Lisp only).
-F The names of functions in calls are required to match
exactly (C, Java, Pascal, Modula-2 and Lisp only).
-n Similarities found are only summarized, not displayed.
-o F The output is written to the file named F.
-p The output is given in similarity percentages; see
below.
-r N The minimum run length is set to N (default is N = 24).
-s The contents of a file are not compared to itself (-s =
not self).
-S The contents of the new files are compared to the old
files only - not between themselves.
-w N The page width used is set to N columns (default is N =
80).
The -p option results in lines of the form F consists for x
% of G material meaning that x % of F's text can also be
found in G. Note that this relation is not symmetric; it is
in fact quite possible for one file to consist for 100 % of
text from another file, while the other file consists for
only 1 % of text of the first file, if their lengths differ
enough. Note also that the granularity of the recognized
text is still governed by the -r option or its default.
Care has been taken to keep all internal processes linear in
the length of the input, with the exception of the matching
process which is almost linear, using a hash table; various
other tables are used for speed-up. If, however, there is
not enough memory for the tables, they are discarded in
order of unimportance, under which conditions the algorithms
revert to their quadratic nature.
AUTHOR
Dick Grune, Vrije Universiteit, Amsterdam.
BUGS
Strong periodicity in the input text (like a table of N
almost identical lines) causes problems. Sim tries to cope
with this but cannot avoid giving appr. log N messages about
it. The best advice is still to take the offending files
out of the game.
Since it uses lex(1) on some systems, it may dump core on
any weird construction that overflows lex's internal
Vrije Universiteit Last change: 2001/11/13 2
User Commands SIM(1)
buffers.
Vrije Universiteit Last change: 2001/11/13 3
|
