add "unit" top-level parsing target

parser/nodes.py

@@ -2,6 +2,8 @@
 class Node(object):
     def __init__(self, children=None):
         self.children = children
+        if self.children is None:
+            self.children = []
 
 class StatementNode(Node):
     def __init__(self, children=None):
@@ -15,3 +17,7 @@ class CExprNode(ExprNode):
     def __init__(self, cstring):
         ExprNode.__init__(self)
         self.cstring = cstring
+
+class UnitNode(Node):
+    def __init__(self, children=None):
+        Node.__init__(self, children)

parser/parserules.py

@@ -2,6 +2,22 @@
 from lexrules import tokens
 from nodes import *
 
+def p_unit(p):
+    'unit : unit_items'
+    p[0] = UnitNode([p[1]])
+
+def p_unit_items(p):
+    'unit_items : unit_item unit_items'
+    p[0] = Node([p[1]] + p[2].children)
+
+def p_unit_items_empty(p):
+    'unit_items : empty'
+    p[0] = p[1]
+
+def p_unit_item_c_stmt(p):
+    'unit_item : c_expr SEMICOLON'
+    p[0] = p[1]
+
 def p_statement(p):
     'statement : expr SEMICOLON'
     p[0] = StatementNode([p[1]])
@@ -13,3 +29,7 @@ def p_expr(p):
 def p_c_expr(p):
     'c_expr : C LPAREN STRING RPAREN'
     p[0] = CExprNode(p[3])
+
+def p_empty(p):
+    'empty :'
+    p[0] = Node()