30 lines
767 B
Python
30 lines
767 B
Python
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def unify(lhs, rhs):
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res = {}
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try:
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unify_res(lhs, rhs, res)
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except Exception:
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return None
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return res
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def unify_res(lhs, rhs, result):
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if lhs.name == 'VAR':
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unify_var(lhs, rhs, result)
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elif rhs.name == 'VAR':
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unify_var(rhs, lhs, result)
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else:
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left = lhs.children
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right = rhs.children
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if len(left) == len(right):
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for i in range(len(left)):
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unify_res(left[i], right[i], result)
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def unify_var(var, rhs, result):
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if rhs.name in ['VAR', 'CONST', 'FUN'] and rhs.value != var.value:
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if var.value in result.keys() \
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and not result[var.value].equals(rhs):
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raise Exception('')
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else:
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result[var.value] = rhs
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