filters/command context: filters get passed their portion + no self

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>

1 files changed, 73 insertions, 3 deletions

diff --git a/command_context.py b/command_context.py
index fc8c7dd..0434c1c 100644
--- a/command_context.py
+++ b/command_context.py
@@ -5,6 +5,7 @@
 """Command context, i.e., state distributed along filters chain"""
 __author__ = "Jan Pokorný <jpokorny @at@ Red Hat .dot. com>"
 
+from collections import MutableMapping
 import logging
 
 from .error import ClufterError
@@ -16,6 +17,75 @@ class CommandContextError(ClufterError):
     pass
 
 
-class CommandContext(dict):
-    """Object representing command context (WIP: use dict for now)"""
-    pass
+class CommandContextBase(MutableMapping):
+    """Object representing command context"""
+    def __init__(self, initial=None, parent=None):
+        if parent is None:
+            parent = self
+        self._parent = parent
+        try:
+            self._dict = dict(initial)
+        except TypeError:
+            self._dict = {}
+
+    def __delitem__(self, key):
+        del self._dict[key]
+
+    def __getitem__(self, key):
+        #return self._dict[key]
+        return self._dict.get(key)  # make it soft-error
+
+    def __iter__(self):
+        return iter(self._dict)
+
+    def __len__(self):
+        return len(self._dict)
+
+    def __setitem__(self, key, value):
+        self._dict[key] = CommandContextBase(initial=value, parent=self) \
+                          if isinstance(value, dict) else value
+
+    @property
+    def parent(self):
+        return self._parent
+
+
+class CommandContext(CommandContextBase):
+    def __init__(self, *args, **kwargs):
+        super(CommandContext, self).__init__(*args, **kwargs)
+        self._filters = {}
+
+    def _wrapping_nested_context(self, obj):
+        class wrapped(CommandContextBase):
+            def __getattribute__(self, name):
+                if name == 'ctxt_wrapped':
+                    return obj
+                elif name == 'ctxt_set':
+                    ret = lambda self, **kwargs: self.update(kwargs)
+                elif name.startswith('ctxt_'):
+                    # by convention, ctxt_* methods are using second
+                    # argument to pass the respective (nested) context
+                    ret = obj.__getattribute__(name)
+                    if callable(ret):
+                        ret = \
+                            lambda this, *args, **kwargs: \
+                                ret(this, this, *args, **kwargs)
+                else:
+                    ret = obj.__getattribute__(name)
+                return ret
+
+            def __setattribute__(self, name, value):
+                obj.__setattribute__(name, value)
+        return (wrapped(parent=self))
+
+    def add_filter(self, flt):
+        existing = self._filters
+        if flt.__class__.name not in existing:
+            existing[flt.__class__.name] = self._wrapping_nested_context(flt)
+
+    def add_filters(self, flts):
+        for flt in flts:
+            self.add_filter(flt)
+
+    def filter(self, which):
+        return self._filters[which]