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swh/core/api/negotiate.py
- This file was added.
# This code is a partial and adapted copy of | |||||
# https://github.com/nickstenning/negotiate | |||||
# and is licensed under the MIT license | |||||
vlorentz: The full license text should be included here ("The above copyright notice and this permission… | |||||
douarddaAuthorUnsubmitted Done Inline Actionsdouardda: D1019 | |||||
# | |||||
# Copyright Nick Stenning | |||||
# 2019 Software Heritage | |||||
from collections import defaultdict | |||||
from decorator import decorator | |||||
from inspect import getcallargs | |||||
class FormatterNotFound(Exception): | |||||
pass | |||||
class Formatter: | |||||
format = None | |||||
mimetypes = [] | |||||
def __init__(self, request_mimetype=None): | |||||
if request_mimetype is None or request_mimetype not in self.mimetypes: | |||||
try: | |||||
self.response_mimetype = self.mimetypes[0] | |||||
except IndexError: | |||||
raise NotImplementedError( | |||||
"%s.mimetypes should be a non-empty list" % | |||||
self.__class__.__name__) | |||||
else: | |||||
self.response_mimetype = request_mimetype | |||||
def configure(self): | |||||
pass | |||||
def render(self, obj): | |||||
raise NotImplementedError( | |||||
"render() should be implemented by Formatter subclasses") | |||||
def __call__(self, obj): | |||||
return self._make_response( | |||||
self.render(obj), content_type=self.response_mimetype) | |||||
def _make_response(self, body, content_type): | |||||
raise NotImplementedError( | |||||
"_make_response() should be implemented by " | |||||
"framework-specific subclasses of Formatter" | |||||
) | |||||
class Negotiator: | |||||
def __init__(self, func): | |||||
self.func = func | |||||
self._formatters = [] | |||||
self._formatters_by_format = defaultdict(list) | |||||
self._formatters_by_mimetype = defaultdict(list) | |||||
def __call__(self, *args, **kwargs): | |||||
result = self.func(*args, **kwargs) | |||||
format = getcallargs(self.func, *args, **kwargs).get('format') | |||||
mimetype = self.best_mimetype() | |||||
try: | |||||
formatter = self.get_formatter(format, mimetype) | |||||
except FormatterNotFound as e: | |||||
return self._abort(404, str(e)) | |||||
return formatter(result) | |||||
def register_formatter(self, formatter, *args, **kwargs): | |||||
self._formatters.append(formatter) | |||||
self._formatters_by_format[formatter.format].append( | |||||
(formatter, args, kwargs)) | |||||
for mimetype in formatter.mimetypes: | |||||
self._formatters_by_mimetype[mimetype].append( | |||||
(formatter, args, kwargs)) | |||||
def get_formatter(self, format=None, mimetype=None): | |||||
if format is None and mimetype is None: | |||||
raise TypeError( | |||||
"get_formatter expects one of the 'format' or 'mimetype' " | |||||
"kwargs to be set") | |||||
if format is not None: | |||||
try: | |||||
# the first added will be the most specific | |||||
formatter_cls, args, kwargs = ( | |||||
self._formatters_by_format[format][0]) | |||||
except IndexError: | |||||
raise FormatterNotFound( | |||||
"Formatter for format '%s' not found!" % format) | |||||
elif mimetype is not None: | |||||
try: | |||||
# the first added will be the most specific | |||||
formatter_cls, args, kwargs = ( | |||||
self._formatters_by_mimetype[mimetype][0]) | |||||
except IndexError: | |||||
raise FormatterNotFound( | |||||
"Formatter for mimetype '%s' not found!" % mimetype) | |||||
formatter = formatter_cls(request_mimetype=mimetype) | |||||
formatter.configure(*args, **kwargs) | |||||
return formatter | |||||
@property | |||||
def accept_mimetypes(self): | |||||
return [m for f in self._formatters for m in f.mimetypes] | |||||
def best_mimetype(self): | |||||
raise NotImplementedError( | |||||
"best_mimetype() should be implemented in " | |||||
"framework-specific subclasses of Negotiator" | |||||
) | |||||
def _abort(self, status_code, err=None): | |||||
raise NotImplementedError( | |||||
"_abort() should be implemented in framework-specific " | |||||
"subclasses of Negotiator" | |||||
) | |||||
def negotiate(negotiator_cls, formatter_cls, *args, **kwargs): | |||||
def _negotiate(f, *args, **kwargs): | |||||
return f.negotiator(*args, **kwargs) | |||||
def decorate(f): | |||||
if not hasattr(f, 'negotiator'): | |||||
f.negotiator = negotiator_cls(f) | |||||
f.negotiator.register_formatter(formatter_cls, *args, **kwargs) | |||||
return decorator(_negotiate, f) | |||||
return decorate |
The full license text should be included here ("The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.")
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