check naming of variables

TODO

@@ -1,15 +1,17 @@
 General
+    Read from file!
     > Rho for vars & funs
     several statements
-    args really just in dictio in function body?
+    > args really just in dictio in function body?
+    parser doing proper separation?
 
 b 
     > basic (BasicValue)
     > check if int
 
 x
     > var (Variable)
-    one word, further specifications? -> check in constructor
+    > one word, further specifications? -> check in constructor
     global, local?
 
 (op1 e)

main.py

@@ -32,4 +32,6 @@
     print()
     print(parse_tree("3 / 4"))
     print()
-    print(parse_tree("let rec f = fun x y -> if y <= 1 then x else f ( x * y ) ( y - 1 ) in f 1"))
+    print(parse_tree("let rec f = fun x y -> if y <= 1 then x else f ( x * y ) ( y - 1 ) in f 1"))
+    print()
+    print(parse_tree("let y_x = 4 in test"))

tree_nodes.py

@@ -17,9 +17,27 @@ def __str__(self):
         super_str = super(BasicValue, self).__str__()
         return super_str + ": " + str(self.value)
 
+def check_var(var):
+    for char in var:
+        if ord(char) < 48 or ord(char) > 57 and ord(char) < 65 or ord(char) > 91 and ord(char) < 97 or ord(char) > 122:
+            if not char == '_':
+                raise Exception('"{}" is not a valid variable name.'.format(var))
+
+    try:
+        int(var[0])
+        raise Exception('"{}" is not a valid variable name.'.format(var))
+    except ValueError:
+        pass
+
+    if var[0] == '_' or var[-1] == '_':
+        raise Exception('"{}" is not a valid variable name.'.format(var))
+
 class Variable(Node):
 
     def __init__(self, tag, var, depth=0):
+        if(tag != "dummy"):
+            check_var(var)
+
         self.var = var
         super(Variable, self).__init__(tag, depth)