Support multiple declarations in the global scope

1 files changed, 20 insertions, 1 deletions

diff --git a/Variables.py b/Variables.py
index 617113f..89c8501 100644
--- a/Variables.py
+++ b/Variables.py
@@ -84,7 +84,10 @@ class GlobalVariables(Variables):
         defined in assembly
         """
         self.defined_names = defined_names
+        # key: variable name, value: name as it appears in assembly
         self.global_vars = {}
+        # a list of variable names which are declared and defined
+        self.global_vars_defined = []
     def _uniqName(self, name):
         """Returns an unique global variable name for assembly"""
         uniq_name = name
@@ -93,6 +96,12 @@ class GlobalVariables(Variables):
             uniq_name = name + "_" + str(i)
             i += 1
         return uniq_name
+    def isDeclared(self, name):
+        """Returns True if the global variable is declared, False otherwise"""
+        return name in self.global_vars
+    def isDefined(self, name):
+        """Returns True if the global variable is defined, False otherwise"""
+        return name in self.global_vars_defined
     def getAddress(self, name):
         """Gets the address for a variable as a tuple containing a register and
         displacement
@@ -100,7 +109,7 @@ class GlobalVariables(Variables):
         To get the address of the variable, add the register value and
         displacement
         """
-        if name in self.global_vars:
+        if self.isDeclared(name):
             return ("GB", self.global_vars[name])
         raise RuntimeError("Use of undefined variable '{}'".format(name))
     def declName(self, name, size=1, is_param=False, is_static=False):
@@ -138,3 +147,13 @@ class GlobalVariables(Variables):
         else:
             # insert size items, initialized with 0
             self.defined_names[var_name] = ["0"] * size
+    def defName(self, name):
+        """Marks a variable name as defined
+
+        Variables may be declared multiple times in the globa scope, but not
+        defined multiple times
+        """
+        assert self.isDeclared(name), "Definition of undeclared '{}'".format(name)
+        if self.isDefined(name):
+            raise RuntimeError("Redefinition of '{}'".format(name))
+        self.global_vars_defined.append(name)