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[auf_roundup.git] / build / lib / roundup / cgi / accept_language.py
1 """Parse the Accept-Language header as defined in RFC2616.
2
3 See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.4
4 for details. This module should follow the spec.
5 Author: Hernan M. Foffani (hfoffani@gmail.com)
6 Some use samples:
7
8 >>> parse("da, en-gb;q=0.8, en;q=0.7")
9 ['da', 'en_gb', 'en']
10 >>> parse("en;q=0.2, fr;q=1")
11 ['fr', 'en']
12 >>> parse("zn; q = 0.2 ,pt-br;q =1")
13 ['pt_br', 'zn']
14 >>> parse("es-AR")
15 ['es_AR']
16 >>> parse("es-es-cat")
17 ['es_es_cat']
18 >>> parse("")
19 []
20 >>> parse(None)
21 []
22 >>> parse(" ")
23 []
24 >>> parse("en,")
25 ['en']
26 """
27
28 import re
29 import heapq
30
31 # regexp for languange-range search
32 nqlre = "([A-Za-z]+[-[A-Za-z]+]*)$"
33 # regexp for languange-range search with quality value
34 qlre = "([A-Za-z]+[-[A-Za-z]+]*);q=([\d\.]+)"
35 # both
36 lre = re.compile(nqlre + "|" + qlre)
37
38 ascii = ''.join([chr(x) for x in range(256)])
39 whitespace = ' \t\n\r\v\f'
40
41 def parse(language_header):
42 """parse(string_with_accept_header_content) -> languages list"""
43
44 if language_header is None: return []
45
46 # strip whitespaces.
47 lh = language_header.translate(ascii, whitespace)
48
49 # if nothing, return
50 if lh == "": return []
51
52 # split by commas and parse the quality values.
53 pls = [lre.findall(x) for x in lh.split(',')]
54
55 # drop uncomformant
56 qls = [x[0] for x in pls if len(x) > 0]
57
58 # use a heap queue to sort by quality values.
59 # the value of each item is 1.0 complement.
60 pq = []
61 for l in qls:
62 if l[0] != '':
63 heapq.heappush(pq, (0.0, l[0]))
64 else:
65 heapq.heappush(pq, (1.0-float(l[2]), l[1]))
66
67 # get the languages ordered by quality
68 # and replace - by _
69 return [x[1].replace('-','_') for x in pq]
70
71 if __name__ == "__main__":
72 import doctest
73 doctest.testmod()
74
75 # vim: set et sts=4 sw=4 :