Refactored some code to try and make it more inline with best pratices. Renamed parser as it conflicted with a standard Python library.

ast_gen.py

@@ -0,0 +1,130 @@
+from base_unit import Token, TokenType
+from collections import deque
+
+class Op:
+	def __init__(self, left, op, right):
+		self.left = left
+		self.op = op
+		self.right = right
+		
+	def __str__(self):
+		return "%s (%s) and (%s)" %(TokenType.get_operator_verb(self.op), self.left, self.right)
+		
+class Num:
+	def __init__(self, token):
+		self.value = token.value
+		
+	def __str__(self):
+		return self.value
+		
+class Variable:
+	def __init__(self, token):
+		self.symbol = token.value
+		self.value = None
+		
+	def __str__(self):
+		if self.value == None:
+			return self.symbol
+		else:
+			return str(self.value)
+		
+class Parser:
+	def __init__(self, tokens):
+		if len(tokens) == 0:
+			raise ValueError("Token list can't be empty")
+		self.bak = deque()			
+		self.variables = {}
+		self.tokens = tokens
+		self.current_token = None
+		self.advance_current_token()
+		self.ast = self.generate_ast()
+
+		
+	def get_tokens(self):
+		new_list = []
+		
+		for t in self.bak:
+			if t.type == TokenType.variable:
+				if t.value in self.variables:
+					new_list.append(Token(self.variables[t.value], TokenType.constant))
+			else:
+				new_list.append(Token(t.value, t.type))
+		return new_list
+		
+	def advance_current_token(self):
+	
+		if len(self.tokens) > 0:
+			if self.current_token != None: self.bak.append(self.current_token)
+			self.current_token = self.tokens.popleft()
+		
+	def factor(self):
+		if self.current_token.type == TokenType.constant:
+			node = Num(self.current_token)
+			self.advance_current_token()
+			return node
+		elif self.current_token.type == 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 == TokenType.exp_start:
+			self.advance_current_token() # (
+			node = self.topLevel()
+			self.advance_current_token() # )
+			return node
+			
+	def lowLevel(self):
+		node = self.factor()
+		
+		while self.current_token.type == TokenType.power:
+			tmp = self.current_token
+			self.advance_current_token()
+			node = Op(left=node, op=tmp.type, right=self.factor())
+				
+		return node
+		
+	def midLevel(self):
+		node = self.lowLevel()
+		
+		while self.current_token.type in (TokenType.multiply, TokenType.divide):
+			tmp = self.current_token
+			self.advance_current_token()
+			node = Op(left=node, op=tmp.type, right=self.lowLevel())
+		
+		return node		
+		
+	def topLevel(self):
+		node = self.midLevel()
+		
+		while self.current_token.type in (TokenType.add, TokenType.subtract):
+			tmp = self.current_token
+			self.advance_current_token()
+			node = Op(left=node, op=tmp.type, right=self.midLevel())
+		
+		return node
+		
+	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