Cleaned up the AST code and updated the calc_engine code.
This commit is contained in:
+7
-143
@@ -1,142 +1,17 @@
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import ptoken
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import tokenizer
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import copy
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from collections import deque
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import parser
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debug = False
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def calculate_results(tokens):
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# Main entry into the calc_engine.
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# Returns the result of arthmetic as described by the token list.
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return process_tokens(tokens, True)
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def calculate_results(node):
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def process_tokens(tokens, top_level = False):
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pending_operations = []
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running_total = 0
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# Flag that inidicates a high priority set of mathmatical operations have occurred.
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# High priority (mulitplation, division, power for instance) act as a pivot on which we can
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# determine whether or not lower priority operations can safely be performed without violating
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# the order of operations.
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p_ops_ran = False
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if type(node) is parser.Num:
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return float(node.value)
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while True:
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if not tokens:
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break
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token = tokens.popleft()
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if not top_level and token.type == ptoken.TokenType.exp_end:
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if tokens:
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look_ahead = tokens[0]
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if look_ahead.type == ptoken.TokenType.power:
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tokens.popleft()
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two_ahead = tokens.popleft()
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tmp = process_tokens(convert_to_deque(pending_operations))
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if two_ahead.type == ptoken.TokenType.exp_start:
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two_ahead = ptoken.Token(process_tokens(tokens), ptoken.TokenType.constant)
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return operate(tmp, two_ahead.value, look_ahead.type)
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break
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if token.type == ptoken.TokenType.exp_start:
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tmp = process_tokens(tokens)
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pending_operations.append(ptoken.Token(tmp, ptoken.TokenType.constant))
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elif token.type == ptoken.TokenType.power:
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look_ahead = tokens.popleft()
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#if look_ahead.type == ptoken.TokenType.exp_start:
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# look_ahead = ptoken.Token(process_tokens(tokens), ptoken.TokenType.constant)
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pending_operations.append(ptoken.Token(operate(pending_operations.pop().value, look_ahead.value, token.type), ptoken.TokenType.constant))
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elif token.type == ptoken.TokenType.add or token.type == ptoken.TokenType.subtract:
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if pending_operations and p_ops_ran:
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tmp = convert_to_deque(pending_operations)
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previous_token = ptoken.Token(handle_pending(tmp), ptoken.TokenType.constant)
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pending_operations = []
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pending_operations.append(previous_token)
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pending_operations.append(token)
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p_ops_ran = False
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elif token.type == ptoken.TokenType.constant:
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pending_operations.append(token)
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p_ops_ran = False
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elif token.type == ptoken.TokenType.multiply or token.type == ptoken.TokenType.divide:
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look_behind = pending_operations.pop()
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look_ahead = tokens.popleft()
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two_ahead = tokens[0]
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if look_ahead.type == ptoken.TokenType.exp_start:
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look_ahead = ptoken.Token(process_tokens(tokens), ptoken.TokenType.constant)
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if two_ahead.type == ptoken.TokenType.power:
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tokens.popleft()
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three_ahead = tokens.popleft()
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if three_ahead.type != ptoken.TokenType.exp_start:
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look_ahead = ptoken.Token(operate(look_ahead.value, three_ahead.value, two_ahead.type), ptoken.TokenType.constant)
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else:
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tmp = process_tokens(tokens)
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look_ahead = ptoken.Token(operate(look_ahead.value, tmp, two_ahead.type), ptoken.TokenType.constant)
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running_total = operate(look_behind.value, look_ahead.value, token.type)
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pending_operations.append(ptoken.Token(running_total, ptoken.TokenType.constant))
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p_ops_ran = True
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#tokenizer.print_token_list(pending_operations)
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if pending_operations:
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if len(pending_operations) == 1:
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return float(pending_operations.pop().value)
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return handle_pending(convert_to_deque(pending_operations))
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return running_total
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#handle add/sub
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def handle_pending(tokens):
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# Effectively, this function handles adding and subtracting as all higher priority mathmatical operations
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# would have already been processed.
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# Returns the result of the addition or subtraction of the provided token list.
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running_total = 0
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previous_token = None
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if len(tokens) == 1:
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return float(tokens[0].value)
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while True:
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if not tokens:
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break
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tmp_token = tokens.popleft()
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if tmp_token.type == ptoken.TokenType.constant:
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previous_token = tmp_token
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elif tmp_token.type == ptoken.TokenType.add or tmp_token.type == ptoken.TokenType.subtract:
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look_ahead = tokens.popleft()
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running_total = operate(previous_token.value, look_ahead.value, tmp_token.type)
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previous_token = ptoken.Token(running_total, ptoken.TokenType.constant)
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return running_total
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def convert_to_deque(tokens):
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# Converts a list into a Deque collection object.
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# Returns a Deque object with the contents of the supplied list or array.
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deq = deque()
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for tk in tokens:
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deq.append(tk)
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return deq
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left = calculate_results(node.left)
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right = calculate_results(node.right)
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return operate(left, right, node.op)
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def operate(n1, n2, tokenType):
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# Utility function to handle dealing with the various mathmatical operations that the engine can process.
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@@ -161,14 +36,3 @@ def operate(n1, n2, tokenType):
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return n1 ** n2
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else:
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raise TypeError("Invalid operator value " + str(tokenType) + ".", tokenType)
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def print_t(tokens):
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# Prints to standard out a flattened representation of a Deque object.
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tmp = copy.deepcopy(tokens)
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while True:
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if not tmp:
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break
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token = tmp.popleft()
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print("%s" %(token.value), end = "")
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print()
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