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# ========================================================================
# Copyright (c) 2007, Metaweb Technologies, Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following
# disclaimer in the documentation and/or other materials provided
# with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY METAWEB TECHNOLOGIES AND CONTRIBUTORS
# ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL METAWEB
# TECHNOLOGIES OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
# ========================================================================
#
# URI Templating in Python
#
# see http://bitworking.org/projects/URI-Templates/
# and http://bitworking.org/news/URI_Templates
#
# note that this implementation may go away soon in
# favor of joe gregorio's own code:
# http://code.google.com/p/uri-templates/
#
#
# this implementation can also parse URIs, as long as the
# template is sufficiently specific. to allow this to work
# the '/' character is forbidden in keys when parsing.
# later it should be possible to loosen this restriction.
#
#
# example:
# from whatever.uritemplate import expand_uri_template
# expand_uri_template('http://{host}/{file}',
# dict(host='example.org',
# file='fred'))
#
# TODO:
# allow parsing to be aware of http://www. and trailing /
# nail down quoting issues
#
import os, sys, re
import urllib
__all__ = ['expand_uri_template', 'URITemplate']
def expand_uri_template(template, args):
"""Expand a URI template using the given args dictionary.
"""
return URITemplate(template).run(args)
def _uri_encode_var(v):
return urllib.quote(v, safe="-_.~!$&'()*+,;=:/?[]#@")
class URITemplate(object):
"""a URITemplate is a URI with simple variable substitution.
"""
VARREF = re.compile(r'\{([0-9a-zA-Z_]+)\}')
def __init__(self, s):
"""Compile a URITemplate from a string.
"""
self.template = s;
self.params = []
tsplit = self.VARREF.split(s)
rxs = ['^']
for i in range(len(tsplit)):
if i % 2:
# track the vars used
self.params.append(tsplit[i])
# vars match any string
# vars are assumed to lack '/' - this is imperfect...
rxs.append('([^/]*)')
else:
# quote special chars regexp interpretation
rxs.append(re.escape(tsplit[i]))
rxs.append('$')
self._parser = re.compile(''.join(rxs))
def __repr__(self):
return '<URITemplate %r>' % self.template
def run (self, args):
"""Expand the template using the given args.
"""
def repl(m):
key = m.group(1)
return _uri_encode_var(args.get(key, ''))
uri = self.VARREF.sub(repl,self.template)
#if self.parse(uri) is None:
# print 're-parsing generated uri failed: %r, %r' % (uri, self.template)
return uri
def parse(self, uri):
"""Try to parse a URI, extracting variable values.
"""
m = self._parser.match(uri)
if m is None:
return None
return dict(zip(self.params, m.groups()))
if __name__ == '__main__':
#
# testcases are imported from the URI::Template module on CPAN
#
import urllib2, simplejson
fp = urllib2.urlopen('http://search.cpan.org/src/BRICAS/URI-Template-0.09/t/data/spec.json')
testsuite = simplejson.loads(fp.read())
vars = dict([(k.encode('utf-8'),v) for k,v in testsuite['variables'].items()])
nsucceed = 0
nfail = 0
for test in testsuite['tests']:
ut = URITemplate(test['template'])
uri = ut.run(vars)
if uri != test['expected']:
print 'FAILED %r expected %r' % (uri, test['expected'])
print ' vars: %r' % (vars,)
nfail += 1
else:
nsucceed += 1
print 'tests: %d succeeded, %d failed' % (nsucceed, nfail)
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