/django_css/versioning/hash/__init__.py

 1import cStringIO
 2from hashlib import md5, sha1
 3import os
 4
 5from django_css.conf import settings
 6from django_css.utils import concat, get_output_filename
 7from django_css.versioning.base import VersioningBase
 8
 9class HashVersioningBase(VersioningBase):
10    def __init__(self, hash_method):
11        self.hash_method = hash_method
12    
13    def needs_update(self, output_file, source_files, version):
14        output_file_name = get_output_filename(output_file, version)
15        ph = settings.COMPRESS_VERSION_PLACEHOLDER
16        of = output_file
17        try:
18            phi = of.index(ph)
19            old_version = output_file_name[phi:phi+len(ph)-len(of)]
20            return (version != old_version), version
21        except ValueError:
22            # no placeholder found, do not update, manual update if needed
23            return False, version
24            
25    def get_version(self, source_files):
26        buf = concat(source_files)
27        s = cStringIO.StringIO(buf)
28        version = self.get_hash(s)
29        s.close()
30        return version            
31            
32    def get_hash(self, f, CHUNK=2**16):
33        m = self.hash_method()
34        while 1:
35            chunk = f.read(CHUNK)
36            if not chunk:
37                break
38            m.update(chunk)
39        return m.hexdigest()
40
41class MD5Versioning(HashVersioningBase):
42    def __init__(self):
43        super(MD5Versioning, self).__init__(md5)
44
45class SHA1Versioning(HashVersioningBase):
46    def __init__(self):
47        super(SHA1Versioning, self).__init__(sha1)