add scope, and symbol class, obsoletes SymbolTable

3 files changed, 54 insertions, 30 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
diff --git a/src/front/symbol.py b/src/front/symbol.py
new file mode 100644
index 0000000..879403f
--- /dev/null
+++ b/src/front/symbol.py
@@ -0,0 +1,34 @@
+class SymbolClass(object):
+    def __init__(self, name):
+        self.name = name
+
+    def __str__(self):
+        return self.name
+
+    def __repr__(self):
+        return "<SymbolClass: %s>" % self
+
+SymbolClass.CONST = SymbolClass("CONST")
+SymbolClass.VAR   = SymbolClass("VAR")
+SymbolClass.FUNC  = SymbolClass("FUNC")
+
+class SymbolType(object):
+    def __init__(self, name):
+        self.name = name
+
+    def __str__(self):
+        return self.name
+
+    def __repr__(self):
+        return "<SymbolType: %s>" % self
+
+SymbolType.INT  = SymbolType("INT")
+SymbolType.BOOL = SymbolType("BOOL")
+
+class Symbol(object):
+    __slots__ = ['cls', 'type', 'value']
+
+    def __init__(self, value, type = SymbolType.INT, cls = SymbolClass.VAR):
+        self.value = value
+        self.type = type
+        self.cls = cls
diff --git a/src/front/symbols.py b/src/front/symbols.py
deleted file mode 100644
index 0f98d83..0000000
--- a/src/front/symbols.py
+++ /dev/null
@@ -1,30 +0,0 @@
-class SymbolTable:
-    def __init__(self):
-        self.symbols = {}
-        return
-
-    def put(self, token, id = None):
-        try:
-            id = int(id)
-        except TypeError:
-            try:
-                id = max(self.symbols.values()) + 1
-            except ValueError:
-                id = 0
-        except ValueError:
-            raise ValueError("only digits as id possible. '%s' is not a number" % id)
-
-        self.symbols[token] = id
-        return id
-
-    def get(self, token):
-        try:
-            return self.symbols[token]
-        except KeyError:
-            return None
-
-    def getOrPut(self, token):
-        try:
-            return self.symbols[token]
-        except KeyError:
-            return self.put(token)