Add support for making an idempotent POST. This allows retrying a POST that was interrupted. It involves creating a post once only (poe) url /rest/data/<class>/@poe/<random_token>. This url acts the same as a post to /rest/data/<class>. However once the @poe url is used, it can't be used for a second POST. To make these changes: 1) Take the body of post_collection into a new post_collection_inner function. Have post_collection call post_collection_inner. 2) Add a handler for POST to rest/data/class/@poe. This will return a unique POE url. By default the url expires after 30 minutes. The POE random token is only good for a specific user and is stored in the session db. 3) Add a handler for POST to rest/data/<class>/@poe/<random token>. The random token generated in 2 is validated for proper class (if token is not generic) and proper user and must not have expired. If everything is valid, call post_collection_inner to process the input and generate the new entry. To make recognition of 2 stable (so it's not confused with rest/data/<:class_name>/<:item_id>), removed @ from Routing::url_to_regex. The current Routing.execute method stops on the first regular expression to match the URL. Since item_id doesn't accept a POST, I was getting 405 bad method sometimes. My guess is the order of the regular expressions is not stable, so sometime I would get the right regexp for /data/<class>/@poe and sometime I would get the one for /data/<class>/<item_id>. By removing the @ from the url_to_regexp, there was no way for the item_id case to match @poe. There are alternate fixes we may need to look at. If a regexp matches but the method does not, return to the regexp matching loop in execute() looking for another match. Only once every possible match has failed should the code return a 405 method failure. Another fix is to implement a more sophisticated mechanism so that @Routing.route("/data/<:class_name>/<:item_id>/<:attr_name>", 'PATCH') has different regexps for matching <:class_name> <:item_id> and <:attr_name>. Currently the regexp specified by url_to_regex is used for every component. Other fixes: Made failure to find any props in props_from_args return an empty dict rather than throwing an unhandled error. Make __init__ for SimulateFieldStorageFromJson handle an empty json doc. Useful for POSTing to rest/data/class/@poe with an empty document. Testing: added testPostPOE to test/rest_common.py that I think covers all the code that was added. Documentation: Add doc to rest.txt in the "Client API" section titled: Safely Re-sending POST". Move existing section "Adding new rest endpoints" in "Client API" to a new second level section called "Programming the REST API". Also a minor change to the simple rest client moving the header setting to continuation lines rather than showing one long line.

"""Parse the Accept-Language header as defined in RFC2616.

See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.4
for details.  This module should follow the spec.
Author: Hernan M. Foffani (hfoffani@gmail.com)
Some use samples:

>>> parse("da, en-gb;q=0.8, en;q=0.7")
['da', 'en_gb', 'en']
>>> parse("en;q=0.2, fr;q=1")
['fr', 'en']
>>> parse("zn; q = 0.2 ,pt-br;q =1")
['pt_br', 'zn']
>>> parse("es-AR")
['es_AR']
>>> parse("es-es-cat")
['es_es_cat']
>>> parse("")
[]
>>> parse(None)
[]
>>> parse("   ")
[]
>>> parse("en,")
['en']
"""

import re
import heapq

# regexp for languange-range search
nqlre = "([A-Za-z]+[-[A-Za-z]+]*)$"
# regexp for languange-range search with quality value
qlre  = "([A-Za-z]+[-[A-Za-z]+]*);q=([\d\.]+)"
# both
lre   = re.compile(nqlre + "|" + qlre)

whitespace = ' \t\n\r\v\f'
try:
    # Python 3.
    remove_ws = (str.maketrans('', '', whitespace),)
except AttributeError:
    # Python 2.
    remove_ws = (None, whitespace)

def parse(language_header):
    """parse(string_with_accept_header_content) -> languages list"""

    if language_header is None: return []

    # strip whitespaces.
    lh = language_header.translate(*remove_ws)

    # if nothing, return
    if lh == "": return []

    # split by commas and parse the quality values.
    pls = [lre.findall(x) for x in lh.split(',')]

    # drop uncomformant
    qls = [x[0] for x in pls if len(x) > 0]

    # use a heap queue to sort by quality values.
    # the value of each item is 1.0 complement.
    pq = []
    for l in qls:
        if l[0] != '':
            heapq.heappush(pq, (0.0, l[0]))
        else:
            heapq.heappush(pq, (1.0-float(l[2]), l[1]))

    # get the languages ordered by quality
    # and replace - by _
    return [x[1].replace('-','_') for x in pq]

if __name__ == "__main__":
    import doctest
    doctest.testmod()

# vim: set et sts=4 sw=4 :