updated tree.py to handle variable nodes

queue.py

@@ -20,8 +20,8 @@ class Queue:
         # When queue is half full, compress it. This 
         # achieves an amortized complexity of O(1) while
         # not letting the list continue to grow unchecked. 
-        if self.frontIdx * 2 > len(self.items):
-            self.__compress()
+        #if self.frontIdx * 2 > len(self.items):
+        #    self.__compress()
 
         item = self.items[self.frontIdx]
         self.frontIdx += 1

tree.py

 # base tree code from http://knuth.luther.edu/~leekent/CS2Plus/chap6/chap6.html
 # changed this code to allow for variable functions, and change infix expressions to postfix
+# added variable node class to consider when both nodes have variables in them
 
 import queue
 
@@ -9,6 +10,16 @@ class TimesNode:
         self.right = right
         
     def eval(self):  
+        '''if check_if_variables(str(self.left.eval()), str(self.right.eval())) == "both_vars":
+            v1 = str(self.left.eval()).split("x")[0]
+            v2 = str(self.right.eval()).split("x")[0]
+            evalStr = v1 + "*" + v2
+            return eval(evalStr)
+        else:
+            return self.left.eval() * self.right.eval()'''
+        #if isinstance(self.left, VariableNode):
+        #    return self.left.getMultiplier() * self.left.getMultiplier()
+        #else:
         return self.left.eval() * self.right.eval()
     
     def inorder(self):
@@ -47,6 +58,17 @@ class NumNode:
     def inorder(self):
         return str(self.num)
 
+class VariableNode:
+    def __init__(self, value):
+        self.value = value
+
+    def eval(self):
+        # get value before x
+        return float(self.value.split("x")[0])
+
+    def inorder(self):
+        return str(self.eval())
+
 def check_if_variables(x, y):
     if 'x' in x and 'x' in y:
         return "both_vars"
@@ -60,7 +82,6 @@ def E(q):
         raise ValueError("Invalid Prefix Expression")
     
     token = q.dequeue()
-
     if token == "+":
         return PlusNode(E(q),E(q))
     
@@ -70,11 +91,15 @@ def E(q):
     if token == "-":
         return MinusNode(E(q), E(q))
     
-    try:
+    #try:
+    if "x" in token:
+        output = VariableNode(token)
+        # make a different class for variable node
+    else:
         output = NumNode(float(token))
-    except:
-        print("Not a valid operation, need variables of like terms")
-        output = NumNode(float(0))
+    #except:
+    #    print("Not a valid operation, need variables of like terms")
+    #    output = NumNode(float(0))
     return output
 
 OPERATORS = set(['+', '-', '*', '/', '(', ')'])
@@ -144,7 +169,8 @@ def split_equation(equation):
     return expressions
 
 def main():
-    exp = split_equation("3 * 4 - 6=0")
+    exp = split_equation("4x * 3x")
+    
     eval_tree(exp[0])
         
     

tutor.py

@@ -101,7 +101,6 @@ class IntelligentTutor(ACTR):
 	goal = Buffer()
 	user = UserState("4x+7=5x+2")
 
-
 	def init():
 		user.get_input()
 		goal.set(user.state)