Add a copy of the nginx builder module

sysadmin/nginx/config/builder/exceptions.py

@@ -0,0 +1,63 @@
+class ConfigBuilderException(BaseException):
+    """
+    Top-level exception for config builder exceptions.
+
+    :param Plugin plugin: plugin that caused the problem
+    :param NginxConfigBuilder builder: current config builder
+    :param str msg: message describing the problem
+    """
+    def __init__(self, msg, **kwargs):
+        self.plugin = kwargs.get('plugin', None)
+        self.cfg = kwargs.get('builder', None)
+        self.msg = msg
+        super(ConfigBuilderException, self).__init__(msg)
+
+    def __str__(self):
+        return '{plugin}: {msg}'.format(plugin=str(self.plugin), msg=self.msg)
+
+
+class ConfigBuilderConflictException(ConfigBuilderException):
+    """
+    Two plugins have conflicting plugins
+
+    :param Plugin loaded_plugin: plugin that's already been added to config builder
+    :param str method_name: name of the method that exists in both plugins
+    """
+    def __init__(self, **kwargs):
+        self.loaded_plugin = kwargs.get('loaded_plugin', None)
+        self.method_name = kwargs.get('method_name', None)
+        super(ConfigBuilderConflictException, self).__init__('we override __str__', **kwargs)
+
+    def __str__(self):
+        repr_string = (
+            "Method `{method_name}` from `{plugin}` conflicts with a "
+            "method of the same name loaded from `{loaded_plugin}`"
+        )
+
+        kwargs = dict(
+            plugin=str(self.plugin),
+            loaded_plugin=str(self.loaded_plugin),
+            method_name=self.method_name
+        )
+
+        return repr_string.format(**kwargs)
+
+
+class ConfigBuilderNoSuchMethodException(ConfigBuilderException, AttributeError):
+    """
+    Exception raised when a user tries to call a non-existent method
+
+    :param str attr: name of the attribute that the user attempted to call
+    """
+    def __init__(self, attr, **kwargs):
+        self.attr = attr
+        super(ConfigBuilderNoSuchMethodException, self).__init__('', **kwargs)
+
+    def __str__(self):
+        errstr = 'No plugins provide method {method}'.format(method=self.attr)
+
+        if self.builder is not None:
+            methods = '\n\t'.join(self.cfg._methods.keys)
+            errstr = errstr + '\nExported methods:{methods}\n\t'.format(methods=methods)
+
+        return errstr