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model.py
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model.py
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class Model:
def __init__(self) -> None:
self.previous_value: str = ''
self.value: str = ''
self.operator: str = ''
def calculate(self, caption) -> str:
if caption == 'C':
self.previous_value = ''
self.value = ''
elif caption == '+/-':
self.value = self.value[1:] if self.value[0] == '-' else '-' + self.value
elif caption == '<':
self.value = self.value[:len(self.value)-1]
elif caption == '.':
if not caption in self.value:
self.value += caption
elif caption == '=':
self.value = str(self._evaluate())
elif isinstance(caption, int):
self.value += str(caption)
else:
if self.value:
self.operator = caption
self.previous_value = self.value
self.value = ''
return self.value
def _evaluate(self):
return eval(self.previous_value + self.operator + self.value)