add scope, and symbol class, obsoletes SymbolTable

1 files changed, 20 insertions, 0 deletions

diff --git a/src/front/scope.py b/src/front/scope.py
new file mode 100644
index 0000000..2cc3018
--- /dev/null
+++ b/src/front/scope.py
@@ -0,0 +1,20 @@
+class Scope(object, DictMixin):
+    def __init__(self, parent):
+        self.parent = parent
+        self.__symbols = {}
+
+    def __getitem__(self, key):
+        try:
+            return self.__symbols[key]
+        except KeyError:
+            return self.parent[key]
+
+    def __setitem__(self, key, item):
+        self.__symbols[key] = item
+
+    def keys(self):
+        keys = self.__symbols.keys()
+        for key in self.parent.keys():
+            if key not in keys:
+                keys.append(key)
+        return keys