| 4710c53d |
1 | """distutils.dep_util\r |
| 2 | \r |
| 3 | Utility functions for simple, timestamp-based dependency of files\r |
| 4 | and groups of files; also, function based entirely on such\r |
| 5 | timestamp dependency analysis."""\r |
| 6 | \r |
| 7 | __revision__ = "$Id$"\r |
| 8 | \r |
| 9 | import os\r |
| 10 | from distutils.errors import DistutilsFileError\r |
| 11 | \r |
| 12 | def newer(source, target):\r |
| 13 | """Tells if the target is newer than the source.\r |
| 14 | \r |
| 15 | Return true if 'source' exists and is more recently modified than\r |
| 16 | 'target', or if 'source' exists and 'target' doesn't.\r |
| 17 | \r |
| 18 | Return false if both exist and 'target' is the same age or younger\r |
| 19 | than 'source'. Raise DistutilsFileError if 'source' does not exist.\r |
| 20 | \r |
| 21 | Note that this test is not very accurate: files created in the same second\r |
| 22 | will have the same "age".\r |
| 23 | """\r |
| 24 | if not os.path.exists(source):\r |
| 25 | raise DistutilsFileError("file '%s' does not exist" %\r |
| 26 | os.path.abspath(source))\r |
| 27 | if not os.path.exists(target):\r |
| 28 | return True\r |
| 29 | \r |
| 30 | return os.stat(source).st_mtime > os.stat(target).st_mtime\r |
| 31 | \r |
| 32 | def newer_pairwise(sources, targets):\r |
| 33 | """Walk two filename lists in parallel, testing if each source is newer\r |
| 34 | than its corresponding target. Return a pair of lists (sources,\r |
| 35 | targets) where source is newer than target, according to the semantics\r |
| 36 | of 'newer()'.\r |
| 37 | """\r |
| 38 | if len(sources) != len(targets):\r |
| 39 | raise ValueError, "'sources' and 'targets' must be same length"\r |
| 40 | \r |
| 41 | # build a pair of lists (sources, targets) where source is newer\r |
| 42 | n_sources = []\r |
| 43 | n_targets = []\r |
| 44 | for source, target in zip(sources, targets):\r |
| 45 | if newer(source, target):\r |
| 46 | n_sources.append(source)\r |
| 47 | n_targets.append(target)\r |
| 48 | \r |
| 49 | return n_sources, n_targets\r |
| 50 | \r |
| 51 | def newer_group(sources, target, missing='error'):\r |
| 52 | """Return true if 'target' is out-of-date with respect to any file\r |
| 53 | listed in 'sources'.\r |
| 54 | \r |
| 55 | In other words, if 'target' exists and is newer\r |
| 56 | than every file in 'sources', return false; otherwise return true.\r |
| 57 | 'missing' controls what we do when a source file is missing; the\r |
| 58 | default ("error") is to blow up with an OSError from inside 'stat()';\r |
| 59 | if it is "ignore", we silently drop any missing source files; if it is\r |
| 60 | "newer", any missing source files make us assume that 'target' is\r |
| 61 | out-of-date (this is handy in "dry-run" mode: it'll make you pretend to\r |
| 62 | carry out commands that wouldn't work because inputs are missing, but\r |
| 63 | that doesn't matter because you're not actually going to run the\r |
| 64 | commands).\r |
| 65 | """\r |
| 66 | # If the target doesn't even exist, then it's definitely out-of-date.\r |
| 67 | if not os.path.exists(target):\r |
| 68 | return True\r |
| 69 | \r |
| 70 | # Otherwise we have to find out the hard way: if *any* source file\r |
| 71 | # is more recent than 'target', then 'target' is out-of-date and\r |
| 72 | # we can immediately return true. If we fall through to the end\r |
| 73 | # of the loop, then 'target' is up-to-date and we return false.\r |
| 74 | target_mtime = os.stat(target).st_mtime\r |
| 75 | \r |
| 76 | for source in sources:\r |
| 77 | if not os.path.exists(source):\r |
| 78 | if missing == 'error': # blow up when we stat() the file\r |
| 79 | pass\r |
| 80 | elif missing == 'ignore': # missing source dropped from\r |
| 81 | continue # target's dependency list\r |
| 82 | elif missing == 'newer': # missing source means target is\r |
| 83 | return True # out-of-date\r |
| 84 | \r |
| 85 | if os.stat(source).st_mtime > target_mtime:\r |
| 86 | return True\r |
| 87 | \r |
| 88 | return False\r |
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