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1 """distutils.dep_util |
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2 |
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3 Utility functions for simple, timestamp-based dependency of files |
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4 and groups of files; also, function based entirely on such |
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5 timestamp dependency analysis.""" |
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6 |
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7 # This module should be kept compatible with Python 2.1. |
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8 |
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9 __revision__ = "$Id: dep_util.py 37828 2004-11-10 22:23:15Z loewis $" |
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10 |
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11 import os |
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12 from distutils.errors import DistutilsFileError |
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13 |
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14 |
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15 def newer (source, target): |
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16 """Return true if 'source' exists and is more recently modified than |
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17 'target', or if 'source' exists and 'target' doesn't. Return false if |
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18 both exist and 'target' is the same age or younger than 'source'. |
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19 Raise DistutilsFileError if 'source' does not exist. |
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20 """ |
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21 if not os.path.exists(source): |
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22 raise DistutilsFileError, "file '%s' does not exist" % source |
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23 if not os.path.exists(target): |
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24 return 1 |
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25 |
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26 from stat import ST_MTIME |
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27 mtime1 = os.stat(source)[ST_MTIME] |
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28 mtime2 = os.stat(target)[ST_MTIME] |
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29 |
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30 return mtime1 > mtime2 |
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31 |
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32 # newer () |
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33 |
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34 |
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35 def newer_pairwise (sources, targets): |
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36 """Walk two filename lists in parallel, testing if each source is newer |
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37 than its corresponding target. Return a pair of lists (sources, |
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38 targets) where source is newer than target, according to the semantics |
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39 of 'newer()'. |
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40 """ |
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41 if len(sources) != len(targets): |
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42 raise ValueError, "'sources' and 'targets' must be same length" |
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43 |
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44 # build a pair of lists (sources, targets) where source is newer |
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45 n_sources = [] |
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46 n_targets = [] |
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47 for i in range(len(sources)): |
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48 if newer(sources[i], targets[i]): |
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49 n_sources.append(sources[i]) |
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50 n_targets.append(targets[i]) |
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51 |
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52 return (n_sources, n_targets) |
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53 |
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54 # newer_pairwise () |
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55 |
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56 |
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57 def newer_group (sources, target, missing='error'): |
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58 """Return true if 'target' is out-of-date with respect to any file |
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59 listed in 'sources'. In other words, if 'target' exists and is newer |
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60 than every file in 'sources', return false; otherwise return true. |
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61 'missing' controls what we do when a source file is missing; the |
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62 default ("error") is to blow up with an OSError from inside 'stat()'; |
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63 if it is "ignore", we silently drop any missing source files; if it is |
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64 "newer", any missing source files make us assume that 'target' is |
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65 out-of-date (this is handy in "dry-run" mode: it'll make you pretend to |
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66 carry out commands that wouldn't work because inputs are missing, but |
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67 that doesn't matter because you're not actually going to run the |
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68 commands). |
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69 """ |
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70 # If the target doesn't even exist, then it's definitely out-of-date. |
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71 if not os.path.exists(target): |
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72 return 1 |
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73 |
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74 # Otherwise we have to find out the hard way: if *any* source file |
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75 # is more recent than 'target', then 'target' is out-of-date and |
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76 # we can immediately return true. If we fall through to the end |
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77 # of the loop, then 'target' is up-to-date and we return false. |
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78 from stat import ST_MTIME |
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79 target_mtime = os.stat(target)[ST_MTIME] |
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80 for source in sources: |
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81 if not os.path.exists(source): |
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82 if missing == 'error': # blow up when we stat() the file |
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83 pass |
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84 elif missing == 'ignore': # missing source dropped from |
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85 continue # target's dependency list |
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86 elif missing == 'newer': # missing source means target is |
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87 return 1 # out-of-date |
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88 |
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89 source_mtime = os.stat(source)[ST_MTIME] |
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90 if source_mtime > target_mtime: |
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91 return 1 |
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92 else: |
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93 return 0 |
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94 |
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95 # newer_group () |