128 lines
4.3 KiB
Python
128 lines
4.3 KiB
Python
# Copyright 2013 by Rackspace Hosting, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Routing utilities."""
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import re
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import six
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from falcon import HTTP_METHODS, responders
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# NOTE(kgriffs): Published method; take care to avoid breaking changes.
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def compile_uri_template(template):
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"""Compile the given URI template string into a pattern matcher.
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This function can be used to construct custom routing engines that
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iterate through a list of possible routes, attempting to match
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an incoming request against each route's compiled regular expression.
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Each field is converted to a named group, so that when a match
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is found, the fields can be easily extracted using
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:py:meth:`re.MatchObject.groupdict`.
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This function does not support the more flexible templating
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syntax used in the default router. Only simple paths with bracketed
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field expressions are recognized. For example::
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/
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/books
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/books/{isbn}
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/books/{isbn}/characters
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/books/{isbn}/characters/{name}
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Also, note that if the template contains a trailing slash character,
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it will be stripped in order to normalize the routing logic.
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Args:
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template(str): The template to compile. Note that field names are
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restricted to ASCII a-z, A-Z, and the underscore character.
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Returns:
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tuple: (template_field_names, template_regex)
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"""
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if not isinstance(template, six.string_types):
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raise TypeError('uri_template is not a string')
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if not template.startswith('/'):
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raise ValueError("uri_template must start with '/'")
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if '//' in template:
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raise ValueError("uri_template may not contain '//'")
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if template != '/' and template.endswith('/'):
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template = template[:-1]
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# template names should be able to start with A-Za-z
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# but also contain 0-9_ in the remaining portion
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expression_pattern = r'{([a-zA-Z]\w*)}'
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# Get a list of field names
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fields = set(re.findall(expression_pattern, template))
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# Convert Level 1 var patterns to equivalent named regex groups
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escaped = re.sub(r'[\.\(\)\[\]\?\*\+\^\|]', r'\\\g<0>', template)
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pattern = re.sub(expression_pattern, r'(?P<\1>[^/]+)', escaped)
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pattern = r'\A' + pattern + r'\Z'
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return fields, re.compile(pattern, re.IGNORECASE)
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def create_http_method_map(resource):
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"""Maps HTTP methods (e.g., 'GET', 'POST') to methods of a resource object.
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Args:
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resource: An object with *responder* methods, following the naming
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convention *on_\**, that correspond to each method the resource
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supports. For example, if a resource supports GET and POST, it
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should define ``on_get(self, req, resp)`` and
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``on_post(self, req, resp)``.
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Returns:
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dict: A mapping of HTTP methods to responders.
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"""
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method_map = {}
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for method in HTTP_METHODS:
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try:
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responder = getattr(resource, 'on_' + method.lower())
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except AttributeError:
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# resource does not implement this method
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pass
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else:
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# Usually expect a method, but any callable will do
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if callable(responder):
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method_map[method] = responder
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# Attach a resource for unsupported HTTP methods
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allowed_methods = sorted(list(method_map.keys()))
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if 'OPTIONS' not in method_map:
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# OPTIONS itself is intentionally excluded from the Allow header
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opt_responder = responders.create_default_options(allowed_methods)
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method_map['OPTIONS'] = opt_responder
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allowed_methods.append('OPTIONS')
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na_responder = responders.create_method_not_allowed(allowed_methods)
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for method in HTTP_METHODS:
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if method not in allowed_methods:
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method_map[method] = na_responder
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return method_map
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