102 lines
2.6 KiB
Python
102 lines
2.6 KiB
Python
import operator
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import readline
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class FifthStack:
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def __init__(self):
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self.stack = []
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self.commands = {
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'push': self.push,
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'pop': self.pop,
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'swap': self.swap,
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'dup': self.dup,
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'+': self.add,
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'-': self.sub,
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'*': self.mul,
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'/': self.div,
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}
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self.binary_ops = {
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'+': operator.add,
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'-': operator.sub,
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'*': operator.mul,
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'/': operator.floordiv,
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}
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def _require(self, number, message):
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if len(self.stack) < number:
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print(message)
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return False
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return True
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def _get_binary_op(self, command):
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return self.binary_ops.get(command)
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def _binary_op(self, operator):
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if not self._require(2, "two numbers required"):
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return
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a, b = self.stack.pop(), self.stack.pop()
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try:
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self.stack.append(operator(a, b))
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except Exception as e:
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print(f"ERROR: {e}")
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self.stack.extend([a, b])
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def push(self, value):
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try:
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self.stack.append(int(value))
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except ValueError:
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print("ERROR: integer required")
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def pop(self, _value):
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if not self.stack:
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print("ERROR: stack empty")
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return
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self.stack.pop()
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def swap(self, _value):
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if not self._require(2, 'two numbers required'):
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return
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self.stack[-1], self.stack[-2] = self.stack[-2], self.stack[-1]
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def dup(self, _value):
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if self._require(1, 'stack empty'):
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self.stack.append(self.stack[-1])
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def add(self, _value):
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self._binary_op(self._get_binary_op('+'))
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def sub(self, _value):
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self._binary_op(self._get_binary_op('-'))
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def mul(self, _value):
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self._binary_op(self._get_binary_op('*'))
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def div(self, _value):
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self._binary_op(self._get_binary_op('/'))
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def execute(self, command):
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tokens = command.lower().strip().split()
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if not tokens:
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return
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command, argument = tokens[0], tokens[1] if len(tokens) > 1 else None
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function = self.commands.get(command)
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try:
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if function: function(argument)
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else: print("ERROR: unknown command")
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except:
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print("ERROR: invalid command")
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def main():
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fifth = FifthStack()
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while True:
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print(f'stack is: {fifth.stack}')
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command = input()
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if command.lower() == 'exit':
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break
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fifth.execute(command)
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if __name__ == '__main__':
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main()
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