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
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
#!/usr/bin/python
# Copyright (c) 2017-2019, The Tor Project, Inc.
# See LICENSE for licensing information
# This script iterates over a list of C files. For each file, it looks at the
# #if/#else C macros, and annotates them with comments explaining what they
# match.
#
# For example, it replaces this:
#
# #ifdef HAVE_OCELOT
# // 500 lines of ocelot code
# #endif
#
# with this:
#
# #ifdef HAVE_OCELOT
# // 500 lines of ocelot code
# #endif /* defined(HAVE_OCELOT) */
#
# Note that only #else and #endif lines are annotated. Existing comments
# on those lines are removed.
import re
# Any block with fewer than this many lines does not need annotations.
LINE_OBVIOUSNESS_LIMIT = 4
# Maximum line width. This includes a terminating newline character.
#
# (This is the maximum before encoding, so that if the the operating system
# uses multiple characers to encode newline, that's still okay.)
LINE_WIDTH=80
class Problem(Exception):
pass
def close_parens_needed(expr):
"""Return the number of left-parentheses needed to make 'expr'
balanced.
"""
return expr.count("(") - expr.count(")")
def truncate_expression(expr, new_width):
"""Given a parenthesized C expression in 'expr', try to return a new
expression that is similar to 'expr', but no more than 'new_width'
characters long.
Try to return an expression with balanced parentheses.
"""
if len(expr) <= new_width:
# The expression is already short enough.
return expr
ellipsis = "..."
# Start this at the minimum that we might truncate.
n_to_remove = len(expr) + len(ellipsis) - new_width
# Try removing characters, one by one, until we get something where
# re-balancing the parentheses still fits within the limit.
while n_to_remove < len(expr):
truncated = expr[:-n_to_remove] + ellipsis
truncated += ")" * close_parens_needed(truncated)
if len(truncated) <= new_width:
return truncated
n_to_remove += 1
return ellipsis
def commented_line(fmt, argument, maxwidth=LINE_WIDTH):
"""
Return fmt%argument, for use as a commented line. If the line would
be longer than maxwidth, truncate argument.
Requires that fmt%"..." will fit into maxwidth characters.
Requires that fmt ends with a newline.
"""
assert fmt.endswith("\n")
result = fmt % argument
if len(result) <= maxwidth:
return result
else:
# How long can we let the argument be? Try filling in the
# format with an empty argument to find out.
max_arg_width = maxwidth - len(fmt % "")
result = fmt % truncate_expression(argument, max_arg_width)
assert len(result) <= maxwidth
return result
def negate(expr):
"""Return a negated version of expr; try to avoid double-negation.
We usually wrap expressions in parentheses and add a "!".
>>> negate("A && B")
'!(A && B)'
But if we recognize the expression as negated, we can restore it.
>>> negate(negate("A && B"))
'A && B'
The same applies for defined(FOO).
>>> negate("defined(FOO)")
'!defined(FOO)'
>>> negate(negate("defined(FOO)"))
'defined(FOO)'
Internal parentheses don't confuse us:
>>> negate("!(FOO) && !(BAR)")
'!(!(FOO) && !(BAR))'
"""
expr = expr.strip()
# See whether we match !(...), with no intervening close-parens.
m = re.match(r'^!\s*\(([^\)]*)\)$', expr)
if m:
return m.group(1)
# See whether we match !?defined(...), with no intervening close-parens.
m = re.match(r'^(!?)\s*(defined\([^\)]*\))$', expr)
if m:
if m.group(1) == "!":
prefix = ""
else:
prefix = "!"
return prefix + m.group(2)
return "!(%s)" % expr
def uncomment(s):
"""
Remove existing trailing comments from an #else or #endif line.
"""
s = re.sub(r'//.*','',s)
s = re.sub(r'/\*.*','',s)
return s.strip()
def translate(f_in, f_out):
"""
Read a file from f_in, and write its annotated version to f_out.
"""
# A stack listing our current if/else state. Each member of the stack
# is a list of directives. Each directive is a 3-tuple of
# (command, rest, lineno)
# where "command" is one of if/ifdef/ifndef/else/elif, and where
# "rest" is an expression in a format suitable for use with #if, and where
# lineno is the line number where the directive occurred.
stack = []
# the stack element corresponding to the top level of the file.
whole_file = []
cur_level = whole_file
lineno = 0
for line in f_in:
lineno += 1
m = re.match(r'\s*#\s*(if|ifdef|ifndef|else|endif|elif)\b\s*(.*)',
line)
if not m:
# no directive, so we can just write it out.
f_out.write(line)
continue
command,rest = m.groups()
if command in ("if", "ifdef", "ifndef"):
# The #if directive pushes us one level lower on the stack.
if command == 'ifdef':
rest = "defined(%s)"%uncomment(rest)
elif command == 'ifndef':
rest = "!defined(%s)"%uncomment(rest)
elif rest.endswith("\\"):
rest = rest[:-1]+"..."
rest = uncomment(rest)
new_level = [ (command, rest, lineno) ]
stack.append(cur_level)
cur_level = new_level
f_out.write(line)
elif command in ("else", "elif"):
# We stay at the same level on the stack. If we have an #else,
# we comment it.
if len(cur_level) == 0 or cur_level[-1][0] == 'else':
raise Problem("Unexpected #%s on %d"% (command,lineno))
if (len(cur_level) == 1 and command == 'else' and
lineno > cur_level[0][2] + LINE_OBVIOUSNESS_LIMIT):
f_out.write(commented_line("#else /* %s */\n",
negate(cur_level[0][1])))
else:
f_out.write(line)
cur_level.append((command, rest, lineno))
else:
# We pop one element on the stack, and comment an endif.
assert command == 'endif'
if len(stack) == 0:
raise Problem("Unmatched #%s on %s"% (command,lineno))
if lineno <= cur_level[0][2] + LINE_OBVIOUSNESS_LIMIT:
f_out.write(line)
elif len(cur_level) == 1 or (
len(cur_level) == 2 and cur_level[1][0] == 'else'):
f_out.write(commented_line("#endif /* %s */\n",
cur_level[0][1]))
else:
f_out.write(commented_line("#endif /* %s || ... */\n",
cur_level[0][1]))
cur_level = stack.pop()
if len(stack) or cur_level != whole_file:
raise Problem("Missing #endif")
import sys,os
for fn in sys.argv[1:]:
with open(fn+"_OUT", 'w') as output_file:
translate(open(fn, 'r'), output_file)
os.rename(fn+"_OUT", fn)
|
