From 3cab3f03e8714e4f50a92c47934daf7161688ff5 Mon Sep 17 00:00:00 2001
From: Garritt McCune <glmccune@gmail.com>
Date: Wed, 1 Jul 2020 22:15:25 -0500
Subject: [PATCH] Updated syntax tree to support variables in the espression.

---
 calc_engine.py |  2 ++
 parser.py      | 25 +++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/calc_engine.py b/calc_engine.py
index c45e121..0786225 100644
--- a/calc_engine.py
+++ b/calc_engine.py
@@ -7,6 +7,8 @@ def calculate_results(node):
 	
 	if type(node) is parser.Num:
 		return float(node.value)
+	elif type(node) is parser.Variable:
+		return node.value
 	
 	left = calculate_results(node.left)
 	right = calculate_results(node.right)
diff --git a/parser.py b/parser.py
index 080a2d3..7d09d8f 100644
--- a/parser.py
+++ b/parser.py
@@ -34,6 +34,7 @@ class Parser:
 	def __init__(self, tokens):
 		if len(tokens) == 0:
 			raise ValueError("Token list can't be empty")
+		self.variables = {}
 		self.tokens = tokens
 		self.current_token = None
 		self.advance_current_token()
@@ -51,6 +52,7 @@ class Parser:
 			return node
 		elif self.current_token.type == token.TokenType.variable:
 			node = Variable(self.current_token)
+			self.variables[self.current_token.value] = node
 			self.advance_current_token()
 			return node
 		elif self.current_token.type == token.TokenType.exp_start:
@@ -91,3 +93,26 @@ class Parser:
 		
 	def generate_ast(self):
 		return self.topLevel()
+		
+	def update_variable(self, symbol, value):
+		if symbol in self.variables:
+			self.variables[symbol].value = float(value)
+		else:
+			raise ValueError("Variable value must be a number.", value)
+			
+	def update_variables(self, variables):
+		if len(variables) == 0:
+			return
+			
+		for symbol in variables:
+			if symbol in self.variables:
+				self.variables[symbol].value = float(variables[symbol])
+			else:
+				raise ValueError("Variable value must be a number.")
+				
+	def get_variable_value_pairs(self):
+		keys = {}
+		
+		for symbol in self.variables:
+			keys[symbol] = self.variables[symbol].value
+		return keys