/usr/lib/python3/dist-packages/mimeparse.py is in python3-mimeparse 0.1.4-1build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 | """MIME-Type Parser
This module provides basic functions for handling mime-types. It can handle
matching mime-types against a list of media-ranges. See section 14.1 of the
HTTP specification [RFC 2616] for a complete explanation.
http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1
Contents:
- parse_mime_type(): Parses a mime-type into its component parts.
- parse_media_range(): Media-ranges are mime-types with wild-cards and a 'q'
quality parameter.
- quality(): Determines the quality ('q') of a mime-type when
compared against a list of media-ranges.
- quality_parsed(): Just like quality() except the second parameter must be
pre-parsed.
- best_match(): Choose the mime-type with the highest quality ('q')
from a list of candidates.
"""
from functools import reduce
__version__ = '0.1.4'
__author__ = 'Joe Gregorio'
__email__ = 'joe@bitworking.org'
__license__ = 'MIT License'
__credits__ = ''
def parse_mime_type(mime_type):
"""Parses a mime-type into its component parts.
Carves up a mime-type and returns a tuple of the (type, subtype, params)
where 'params' is a dictionary of all the parameters for the media range.
For example, the media range 'application/xhtml;q=0.5' would get parsed
into:
('application', 'xhtml', {'q', '0.5'})
"""
parts = mime_type.split(';')
params = dict([tuple([s.strip() for s in param.split('=', 1)])
for param in parts[1:]
])
full_type = parts[0].strip()
# Java URLConnection class sends an Accept header that includes a
# single '*'. Turn it into a legal wildcard.
if full_type == '*':
full_type = '*/*'
(type, subtype) = full_type.split('/')
return (type.strip(), subtype.strip(), params)
def parse_media_range(range):
"""Parse a media-range into its component parts.
Carves up a media range and returns a tuple of the (type, subtype,
params) where 'params' is a dictionary of all the parameters for the media
range. For example, the media range 'application/*;q=0.5' would get parsed
into:
('application', '*', {'q', '0.5'})
In addition this function also guarantees that there is a value for 'q'
in the params dictionary, filling it in with a proper default if
necessary.
"""
(type, subtype, params) = parse_mime_type(range)
if not 'q' in params or not params['q'] or \
not float(params['q']) or float(params['q']) > 1\
or float(params['q']) < 0:
params['q'] = '1'
return (type, subtype, params)
def fitness_and_quality_parsed(mime_type, parsed_ranges):
"""Find the best match for a mime-type amongst parsed media-ranges.
Find the best match for a given mime-type against a list of media_ranges
that have already been parsed by parse_media_range(). Returns a tuple of
the fitness value and the value of the 'q' quality parameter of the best
match, or (-1, 0) if no match was found. Just as for quality_parsed(),
'parsed_ranges' must be a list of parsed media ranges.
"""
best_fitness = -1
best_fit_q = 0
(target_type, target_subtype, target_params) =\
parse_media_range(mime_type)
for (type, subtype, params) in parsed_ranges:
type_match = (type == target_type or
type == '*' or
target_type == '*')
subtype_match = (subtype == target_subtype or
subtype == '*' or
target_subtype == '*')
if type_match and subtype_match:
param_matches = reduce(lambda x, y: x + y, [1 for (key, value) in
list(target_params.items()) if key != 'q' and
key in params and value == params[key]], 0)
fitness = (type == target_type) and 100 or 0
fitness += (subtype == target_subtype) and 10 or 0
fitness += param_matches
if fitness > best_fitness:
best_fitness = fitness
best_fit_q = params['q']
return best_fitness, float(best_fit_q)
def quality_parsed(mime_type, parsed_ranges):
"""Find the best match for a mime-type amongst parsed media-ranges.
Find the best match for a given mime-type against a list of media_ranges
that have already been parsed by parse_media_range(). Returns the 'q'
quality parameter of the best match, 0 if no match was found. This function
bahaves the same as quality() except that 'parsed_ranges' must be a list of
parsed media ranges. """
return fitness_and_quality_parsed(mime_type, parsed_ranges)[1]
def quality(mime_type, ranges):
"""Return the quality ('q') of a mime-type against a list of media-ranges.
Returns the quality 'q' of a mime-type when compared against the
media-ranges in ranges. For example:
>>> quality('text/html','text/*;q=0.3, text/html;q=0.7,
text/html;level=1, text/html;level=2;q=0.4, */*;q=0.5')
0.7
"""
parsed_ranges = [parse_media_range(r) for r in ranges.split(',')]
return quality_parsed(mime_type, parsed_ranges)
def best_match(supported, header):
"""Return mime-type with the highest quality ('q') from list of candidates.
Takes a list of supported mime-types and finds the best match for all the
media-ranges listed in header. The value of header must be a string that
conforms to the format of the HTTP Accept: header. The value of 'supported'
is a list of mime-types. The list of supported mime-types should be sorted
in order of increasing desirability, in case of a situation where there is
a tie.
>>> best_match(['application/xbel+xml', 'text/xml'],
'text/*;q=0.5,*/*; q=0.1')
'text/xml'
"""
split_header = _filter_blank(header.split(','))
parsed_header = [parse_media_range(r) for r in split_header]
weighted_matches = []
pos = 0
for mime_type in supported:
weighted_matches.append((fitness_and_quality_parsed(mime_type,
parsed_header), pos, mime_type))
pos += 1
weighted_matches.sort()
return weighted_matches[-1][0][1] and weighted_matches[-1][2] or ''
def _filter_blank(i):
for s in i:
if s.strip():
yield s
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