1 files changed, 120 insertions, 0 deletions
diff --git a/paste/config.py b/paste/config.py
new file mode 100644
index 0000000..c531579
--- /dev/null
+++ b/paste/config.py
@@ -0,0 +1,120 @@
+# (c) 2006 Ian Bicking, Philip Jenvey and contributors
+# Written for Paste (http://pythonpaste.org)
+# Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php
+"""Paste Configuration Middleware and Objects"""
+from paste.registry import RegistryManager, StackedObjectProxy
+
+__all__ = ['DispatchingConfig', 'CONFIG', 'ConfigMiddleware']
+
+class DispatchingConfig(StackedObjectProxy):
+    """
+    This is a configuration object that can be used globally,
+    imported, have references held onto.  The configuration may differ
+    by thread (or may not).
+
+    Specific configurations are registered (and deregistered) either
+    for the process or for threads.
+    """
+    # @@: What should happen when someone tries to add this
+    # configuration to itself?  Probably the conf should become
+    # resolved, and get rid of this delegation wrapper
+
+    def __init__(self, name='DispatchingConfig'):
+        super(DispatchingConfig, self).__init__(name=name)
+        self.__dict__['_process_configs'] = []
+
+    def push_thread_config(self, conf):
+        """
+        Make ``conf`` the active configuration for this thread.
+        Thread-local configuration always overrides process-wide
+        configuration.
+
+        This should be used like::
+
+            conf = make_conf()
+            dispatching_config.push_thread_config(conf)
+            try:
+                ... do stuff ...
+            finally:
+                dispatching_config.pop_thread_config(conf)
+        """
+        self._push_object(conf)
+
+    def pop_thread_config(self, conf=None):
+        """
+        Remove a thread-local configuration.  If ``conf`` is given,
+        it is checked against the popped configuration and an error
+        is emitted if they don't match.
+        """
+        self._pop_object(conf)
+
+    def push_process_config(self, conf):
+        """
+        Like push_thread_config, but applies the configuration to
+        the entire process.
+        """
+        self._process_configs.append(conf)
+
+    def pop_process_config(self, conf=None):
+        self._pop_from(self._process_configs, conf)
+
+    def _pop_from(self, lst, conf):
+        popped = lst.pop()
+        if conf is not None and popped is not conf:
+            raise AssertionError(
+                "The config popped (%s) is not the same as the config "
+                "expected (%s)"
+                % (popped, conf))
+
+    def _current_obj(self):
+        try:
+            return super(DispatchingConfig, self)._current_obj()
+        except TypeError:
+            if self._process_configs:
+                return self._process_configs[-1]
+            raise AttributeError(
+                "No configuration has been registered for this process "
+                "or thread")
+    current = current_conf = _current_obj
+
+CONFIG = DispatchingConfig()
+
+no_config = object()
+class ConfigMiddleware(RegistryManager):
+    """
+    A WSGI middleware that adds a ``paste.config`` key (by default)
+    to the request environment, as well as registering the
+    configuration temporarily (for the length of the request) with
+    ``paste.config.CONFIG`` (or any other ``DispatchingConfig``
+    object).
+    """
+
+    def __init__(self, application, config, dispatching_config=CONFIG,
+                 environ_key='paste.config'):
+        """
+        This delegates all requests to `application`, adding a *copy*
+        of the configuration `config`.
+        """
+        def register_config(environ, start_response):
+            popped_config = environ.get(environ_key, no_config)
+            current_config = environ[environ_key] = config.copy()
+            environ['paste.registry'].register(dispatching_config,
+                                               current_config)
+
+            try:
+                app_iter = application(environ, start_response)
+            finally:
+                if popped_config is no_config:
+                    environ.pop(environ_key, None)
+                else:
+                    environ[environ_key] = popped_config
+            return app_iter
+
+        super(self.__class__, self).__init__(register_config)
+
+def make_config_filter(app, global_conf, **local_conf):
+    conf = global_conf.copy()
+    conf.update(local_conf)
+    return ConfigMiddleware(app, conf)
+
+make_config_middleware = ConfigMiddleware.__doc__