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50 51 # newer_pairwise () 52 53 54 def newer_group (sources, target, missing='error'): 55 """Return true if 'target' is out-of-date with respect to any file 56 listed in 'sources'.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drop any missing source files; if it is 61 "newer", any missing source files make us assume that 'target' is 62 out-of-date (this is handy in "dry-run" mode: it'll make you pretend to 63 carry out commands that wouldn't work because inputs are missing, but 64 that doesn't matter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you're not actually going to run the 65 commands). 66 """ 67 # If the target doesn't even exist, then it's definitely out-of-date. 68 if not os.path.exists(target): 69 return 1 70 71 # Otherwise we have to find out the hard way: if *any* source file 72 # is more recent than 'target', then 'target' is out-of-date and 73 # we can immediately return true.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