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1 | """distutils.dep_util | |
2 | ||
3 | Utility functions for simple, timestamp-based dependency of files | |
4 | and groups of files; also, function based entirely on such | |
5 | timestamp dependency analysis.""" | |
6 | ||
7 | # This module should be kept compatible with Python 1.5.2. | |
8 | ||
9 | __revision__ = "$Id$" | |
10 | ||
11 | import os | |
12 | from distutils.errors import DistutilsFileError | |
13 | ||
14 | ||
15 | def newer (source, target): | |
16 | """Return true if 'source' exists and is more recently modified than | |
17 | 'target', or if 'source' exists and 'target' doesn't. Return false if | |
18 | both exist and 'target' is the same age or younger than 'source'. | |
19 | Raise DistutilsFileError if 'source' does not exist. | |
20 | """ | |
21 | if not os.path.exists(source): | |
22 | raise DistutilsFileError, "file '%s' does not exist" % source | |
23 | if not os.path.exists(target): | |
24 | return 1 | |
25 | ||
26 | from stat import ST_MTIME | |
27 | mtime1 = os.stat(source)[ST_MTIME] | |
28 | mtime2 = os.stat(target)[ST_MTIME] | |
29 | ||
30 | return mtime1 > mtime2 | |
31 | ||
32 | # newer () | |
33 | ||
34 | ||
35 | def newer_pairwise (sources, targets): | |
36 | """Walk two filename lists in parallel, testing if each source is newer | |
37 | than its corresponding target. Return a pair of lists (sources, | |
38 | targets) where source is newer than target, according to the semantics | |
39 | of 'newer()'. | |
40 | """ | |
41 | if len(sources) != len(targets): | |
42 | raise ValueError, "'sources' and 'targets' must be same length" | |
43 | ||
44 | # build a pair of lists (sources, targets) where source is newer | |
45 | n_sources = [] | |
46 | n_targets = [] | |
47 | for i in range(len(sources)): | |
48 | if newer(sources[i], targets[i]): | |
49 | n_sources.append(sources[i]) | |
50 | n_targets.append(targets[i]) | |
51 | ||
52 | return (n_sources, n_targets) | |
53 | ||
54 | # newer_pairwise () | |
55 | ||
56 | ||
57 | def newer_group (sources, target, missing='error'): | |
58 | """Return true if 'target' is out-of-date with respect to any file | |
59 | listed in 'sources'. In other words, if 'target' exists and is newer | |
60 | than every file in 'sources', return false; otherwise return true. | |
61 | 'missing' controls what we do when a source file is missing; the | |
62 | default ("error") is to blow up with an OSError from inside 'stat()'; | |
63 | if it is "ignore", we silently drop any missing source files; if it is | |
64 | "newer", any missing source files make us assume that 'target' is | |
65 | out-of-date (this is handy in "dry-run" mode: it'll make you pretend to | |
66 | carry out commands that wouldn't work because inputs are missing, but | |
67 | that doesn't matter because you're not actually going to run the | |
68 | commands). | |
69 | """ | |
70 | # If the target doesn't even exist, then it's definitely out-of-date. | |
71 | if not os.path.exists(target): | |
72 | return 1 | |
73 | ||
74 | # Otherwise we have to find out the hard way: if *any* source file | |
75 | # is more recent than 'target', then 'target' is out-of-date and | |
76 | # we can immediately return true. If we fall through to the end | |
77 | # of the loop, then 'target' is up-to-date and we return false. | |
78 | from stat import ST_MTIME | |
79 | target_mtime = os.stat(target)[ST_MTIME] | |
80 | for source in sources: | |
81 | if not os.path.exists(source): | |
82 | if missing == 'error': # blow up when we stat() the file | |
83 | pass | |
84 | elif missing == 'ignore': # missing source dropped from | |
85 | continue # target's dependency list | |
86 | elif missing == 'newer': # missing source means target is | |
87 | return 1 # out-of-date | |
88 | ||
89 | source_mtime = os.stat(source)[ST_MTIME] | |
90 | if source_mtime > target_mtime: | |
91 | return 1 | |
92 | else: | |
93 | return 0 | |
94 | ||
95 | # newer_group () |