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
|
"""Cache lines from Python source files.
This is intended to read lines from modules imported -- hence if a filename
is not found, it will look down the module search path for a file by
that name.
"""
import functools
import sys
import os
import tokenize
__all__ = ["getline", "clearcache", "checkcache", "lazycache"]
# The cache. Maps filenames to either a thunk which will provide source code,
# or a tuple (size, mtime, lines, fullname) once loaded.
cache = {}
def clearcache():
"""Clear the cache entirely."""
cache.clear()
def getline(filename, lineno, module_globals=None):
"""Get a line for a Python source file from the cache.
Update the cache if it doesn't contain an entry for this file already."""
lines = getlines(filename, module_globals)
if 1 <= lineno <= len(lines):
return lines[lineno - 1]
return ''
def getlines(filename, module_globals=None):
"""Get the lines for a Python source file from the cache.
Update the cache if it doesn't contain an entry for this file already."""
if filename in cache:
entry = cache[filename]
if len(entry) != 1:
return cache[filename][2]
try:
return updatecache(filename, module_globals)
except MemoryError:
clearcache()
return []
def checkcache(filename=None):
"""Discard cache entries that are out of date.
(This is not checked upon each call!)"""
if filename is None:
filenames = list(cache.keys())
elif filename in cache:
filenames = [filename]
else:
return
for filename in filenames:
entry = cache[filename]
if len(entry) == 1:
# lazy cache entry, leave it lazy.
continue
size, mtime, lines, fullname = entry
if mtime is None:
continue # no-op for files loaded via a __loader__
try:
stat = os.stat(fullname)
except OSError:
del cache[filename]
continue
if size != stat.st_size or mtime != stat.st_mtime:
del cache[filename]
def updatecache(filename, module_globals=None):
"""Update a cache entry and return its list of lines.
If something's wrong, print a message, discard the cache entry,
and return an empty list."""
if filename in cache:
if len(cache[filename]) != 1:
del cache[filename]
if not filename or (filename.startswith('<') and filename.endswith('>')):
return []
fullname = filename
try:
stat = os.stat(fullname)
except OSError:
basename = filename
# Realise a lazy loader based lookup if there is one
# otherwise try to lookup right now.
if lazycache(filename, module_globals):
try:
data = cache[filename][0]()
except (ImportError, OSError):
pass
else:
if data is None:
# No luck, the PEP302 loader cannot find the source
# for this module.
return []
cache[filename] = (
len(data),
None,
[line + '\n' for line in data.splitlines()],
fullname
)
return cache[filename][2]
# Try looking through the module search path, which is only useful
# when handling a relative filename.
if os.path.isabs(filename):
return []
for dirname in sys.path:
try:
fullname = os.path.join(dirname, basename)
except (TypeError, AttributeError):
# Not sufficiently string-like to do anything useful with.
continue
try:
stat = os.stat(fullname)
break
except OSError:
pass
else:
return []
try:
with tokenize.open(fullname) as fp:
lines = fp.readlines()
except OSError:
return []
if lines and not lines[-1].endswith('\n'):
lines[-1] += '\n'
size, mtime = stat.st_size, stat.st_mtime
cache[filename] = size, mtime, lines, fullname
return lines
def lazycache(filename, module_globals):
"""Seed the cache for filename with module_globals.
The module loader will be asked for the source only when getlines is
called, not immediately.
If there is an entry in the cache already, it is not altered.
:return: True if a lazy load is registered in the cache,
otherwise False. To register such a load a module loader with a
get_source method must be found, the filename must be a cachable
filename, and the filename must not be already cached.
"""
if filename in cache:
if len(cache[filename]) == 1:
return True
else:
return False
if not filename or (filename.startswith('<') and filename.endswith('>')):
return False
# Try for a __loader__, if available
if module_globals and '__loader__' in module_globals:
name = module_globals.get('__name__')
loader = module_globals['__loader__']
get_source = getattr(loader, 'get_source', None)
if name and get_source:
get_lines = functools.partial(get_source, name)
cache[filename] = (get_lines,)
return True
return False
|
